Rather than worrying about settings for the AI, you might consider imposing limits on yourself that force you to play in ways that are different from your normal style.

Pick a victory style ahead of time, and only go for that one.

If you normally get a religion, don't allow yourself to do so.

Limit the number of cities you are allowed to have at one time, or never allow yourself to declare war on an AI.

Not only will things like this make the game more difficult, but they often get you to explore parts of the game that you don't generally pay attention to, which can be fun and interesting.

You could play multiplayer, since the AIs will never be as good as a skilled human.

You could modify the AI personalities to make them more effective (give them more focus on science) and you could just play 2v1 against AI opponents.

You could also choose intentionally weak civs for a map, like playing Polynesia on a landlocked map.

AI difficulty settings don't really help much.

The AI is actually quite stupid, and the higher settings simply add more cheats to it, which usually only results in adding frustration, rather than challenge.

However, if you're not against using mods, try the Smart AI mod.

It's mostly just a bunch of tweaks, but it helps a bit.

You can get the mod through the Steam Workshop here: http://steamcommunity.com/sharedfiles/filedetails/?id=233424615

There are a few ways..

I'll go through a few: 1)

Play versus Human players

For large strategy games like this, AI will always be flawed.

Nothing is more challenging than playing against actual human players that can adapt to your strategies.

Play with friends, or try joining/creating a lobby..

usually there are at least a few games going on.

2) Don't use tricks If you want to win via science, culture, or diplomacy..

it's almost a guaranteed victory if you make everyone happy (so they don't go to war with you).

If you don't use tricks to make them happy (ex: giving 1 gold per turn to each civ), they'll be more interested in going to war with you.

Stop using these cheap tricks!

3) Try conquest Conquest is harder than other strategies, especially if you start off conquering early in the game.

4) Don't play maps with a lot of water

The AI is especially retarded when it comes to the sea...

they never buy a fleet (except for maybe Elizabeth), and their tactics

when attacking through sea is so easy to overcome... play large land maps against the AI.

5) Limit yourself

I don't like using this option because it means you're purposely doing something you wouldn't normally do... but try playing a game by limiting yourself in some way..

examples: Play the game with only one city. Play the game without diplomacy (don't even accept embassies).

Play the game with all AI players on teams.

Use bad civs.

etc...

There's a lot of self-imposed requirements you can follow: Kill your warrior upon start - not fun with raging barbarians Build every wonder

Pick some fights at inappropriate times (e.g. right when you start on the Pyramids)

Downside of this is that it's deteriorating your perfect, big game strategy, but it is fun regardless!

I think the best challenge is to play against actual humans.

It would be best to play multiplayer with steam friends though.

Just going to the multiplayer lobby and joining a game might make it too difficult to actually start a game, much less get a game going past 100 turns.

Multiplayer could then all play on deity level with raging barbarians, low resources and no start bias.

This is also another reason why you should play with steam friends you know, since random players might leave if the game is too tough.

Question: So I’ve been trying to create a truly difficult game of Civilization. I want to test my skills. So, obviously first thing to do is put the AI on Deity, and I've ticked the box for Rampaging Barbarians.  What other settings can I play about with to make the game more difficult?

How can I make Civilization V more difficult?

The AIs will never be good as a skilled human. The best challenge is to play against actual humans.

Mods can help making the game harder, but most players prefer to compete against humans.

People recommending playing against real humans.


As said in the Feed The Beast wiki, you can take the creosote oil out with a bucket.

Here's the quote: Placing a Bucket in the Coke Oven's inventory (on the right) will fill the Bucket with Creosote Oil.

Wooden Waterproof Pipes can also be used to take Creosote Oil into Tanks.

The Coke Oven will not function if the inventory of the Coke Oven is full with Creosote Oil.

Each time a coal is burned to produce a Coal Coke, 500 mB (half a bucket) of Creosete Oil will be produced.

If you absolutly want to use a pipe to get it out, you need to use Buildcraft pipes, otherwise it wont work.

Here is a video tutorial explaining how you can do it.

Things to check: Were the fluiducts set to extract?

Were they powered by redstone?

were they set so that redstone enabled them, or were they set

so the redstone disabled them?

Just now discovered a way to do this without any extra mods, like BuildCraft: Place a pump adjancent to the place you want the oven to be; do not place the oven itself yet.

It won't require power, so don't bother with connectors.

Use the Engineer's Hammer once on the pump on the side where the oven will be.

It will turn blue - it's the input side now.

Use the hammer again on any other side, twice.

It will first turn blue, then orange - it's the output side now.

You may now place fluid pipes here and stretch them to whenever you want - tanks work perfectly for that purpose.

Build the actual oven and activate with the hammer, as described on it's page in the manual.

Supply the pump with a redstone signal - placing a lever on it and toggling it on will suffice.

Done!

The creosote oil is now going to whenever you want it to.

Placing the pump first was necessary because later the oven would obstruct its clickable side.

Hope that helped. :)

I have pumped creosote oil from the left and right sides in several packs.

I've used Fluiducts, Buildcraft waterproof wooden pipes and EnderIO Fluid Conduits.

Never had any problems.

The problems come when the tech you are using isn't configured right.

In your case your Fluiducts would need to be set to extract.

Basically hit the bigger part attached to the side of the Coke Oven with a wrench or crescent hammer until you see an arrow head facing away from the oven.

This is explicit extract mode.

Then you either need to install a Pneumatic Servo and configure it to ignore redstone, or you need to place lever below/above the arrow on the pipe and turn the lever on.

A redstone torch would do the same thing.

On the advanced coke oven, the liquid pull point is the hole at the bottom of the large plate.

A servo and some fluiducts will draw the creosote out.

Question: My Coke Oven has about 30k's worth of Creosote Oil, which I want to store in a tank, but I cannot get it out. I've tried putting Fluiducts all around it and it doesn't come out at all. Is there something special I need to do to get the oil out?

How do you pump Creosote Oil out of a Coke Oven

Take the creosote oil out with a bucket.

In order to pump creosote oil out of a coke oven, without investing too much time, mods usage is required.

While a user is implying that Mods can help too.


If you signed into Google+ before wiping your base, you can log into Google+ to recover your base.

(iOS users can also use GameCenter for this)

Beyond that, you'll have to contact SuperCell.

They've got a FAQ page for this :

You can submit a help request by sending a message from the game on your device.

To send an in-game message, tap the in-game settings icon, select "Help and Feedback", and then tap "Report an Issue".

That will assure we have all the necessary data to make the recovering process as quick as possible.

For this, you'll need to know the exact name, clan, level, and town hall level of both bases (the one you wiped and the current, mostly empty one).

If you are moving from iOS to Android, there are instructions in the Device Linking Guide provided by SuperCell: VERY IMPORTANT NOTE :

Play through the tutorial on the new device and use link BEFORE reaching Town Hall level 4 and before making in app purchases.

If you need further assistance or experience any issues with linking your devices, please contact player support via the in-app reporting feature in the in-game settings menu!

You'll find it under the Help & Settings option.

In order to transfer your village between and iOS and Android device, it needs to be connected to Game Center/Google+.

You can verify the Game Center connection on iOS by logging into Game Center and opening the game from the Game Center's 'Games' tab.

For Android, open Clash of Clans and connect your village to Google+ in the in-game settings by clicking the Google+ sign in button.

Everything verified?

To move your village between your devices follow these steps: Open Clash of Clans on both your Android and iOS devices (source device and target device).

Open the in-game settings window on both devices.

Press

the 'Link a device' button.

Select OLD DEVICE on the device you would like to move your village FROM Select NEW DEVICE on the device you would like to move your village TO Select which type of device you want to link your village TO.

If you are linking your village from an iOS to an iOS device, use the Game Center User Guide .

If you are linking your village from one Android device to another Android Device, try out Google Play Guide located here: Google+ User Guide .

STOP!!!!

Before you proceed, please make sure you have played through the tutorial and not made a purchase before TH4.

Read the VERY IMPORTANT NOTE located above.

Use the device code provided on your OLD DEVICE and enter it on your NEW DEVICE.

You have a 5 minute window of time before your code is invalid!the other, your village will be on both devices.

After you have successfully copied the village transfer code from one device to the other, your village will be on both devices.

If you connected your Google Account before playing, you can just simply connect it again and it should automatically continue where you left of.

If you didn't connect your account beforehand, enjoy playing from the start!

If you know the name of the old village, you can recover your village that way.

Taken from an article on cocland.com and one on Clash of Clans Wikia : In Clash of Clans, go to Settings -> Help & Support.

Tap on the send icon to the right.

Give as much detail as possible as you can about your old village.

At the very least, you'll need the name of your old village and new village as well as the name of your clan.

If you can, provide additional details.

Some additional details that will help: the level of the two villages the level of the town halls when you started playing the old village when you last logged into the old village a screenshot of the old village If the CoC support staff is able to find your village, they'll send you a code to help you recover it.

The Wikia aticle recommends that you do not surpass Town Hall level 4 in the new village as it may make recovery more difficult.

If you were playing on an android device

and you linked your account to Google+, you can simply log back in on the same account and recover your village instantly.

Note: This assumes you are using some form of emulation service for Android (BlueStacks)

This game does not support backed up saves games using Google Play Games.

Therefore, your Google Play account does not have a backup as a result of logging into your Google Account.

There is no manual way to save your progress over, unless you use it on Android or iOS, in which your Google or iTunes account has saved the progress for you

Only they (developers) can affect the changes.

If you give them your details and your issue, the should be able to transfer the items over (if it is in their Terms & Service etc.)

Right now, their forums is down, so you would need to contact them directly for help.

EMAILS:

clashofclans.feedback@supercell.com hayday.feedback@supercell.com boombeach.feedback@supercell.com WEBSITES: Support Page Website Forums (OFFLINE ATM)

I'm sorry, as we are not Supercell, we most likely cannot help you with this.

The next thing you should do is contact Supercell directly.

This article on their support page might be a good starting point.

It does say to contact them in-game (via settings > help), but I cannot find any option to contact Supercell.

It may only be available to newly started games, so make sure you check your device.

Good luck getting your village back!

Question: I unintentionally and stupidly wiped my Clash of Clans game data. I went to Application Manager on my Android and clicked 'Clear data'. (I used this for fixes before and it never started a new game.)   Now, my level 60 or so base has been wiped as if was to start a new game. Have I doomed myself to starting again or is there a way in which I can retrieve my old game save? Maybe by contacting Supercell? I have a snapshot of my base.

How do I recover my old Clash of Clans (COC) game save & base?

The only way to recover progress is if you did bind a google account.

The community explains how to recover progress.


You can use command blocks.

Place a redstone torch under the block you want to break and a command block above.

Then, the command is: /setblock ~

~-1 ~ minecraft:air 0 destroy Other than that, there is no vanilla way.

(this is also not very vanilla)

To pick it up by a hopper place the torch on a wall under it and place the hopper at least 2 blocks under the cobble to make sure that you don't power the hopper

Not possible in vanilla.

For automatization you should use some mods, they are just for this.

If you want really a lot of cobblestone vanilla way, just make yourself Effi 5 diamond pickaxe and place beacon with Haste 2 , then you can break mountains in seconds :) If you do skyblock, automatic grinding of stone is maybe useful, but can be considered as "cheating" :)

Here is a proof-of-concept video, illustrating a system using TNT .

The cobble is generated and blown up by TNT; and then transported by water to (presumably) a hopper.

There are other ways to achieve the desired effect -such as using creepers/withers/etc (through a monster spawner or darkened room) - which could be done, for example, by using creepers and ocelots with directing corridors, to get the creeper to where you wanted him to go .

If you're looking for an easy way, just get a whole bunch of gunpowder and make loads of TNT.

Otherwise, I'd suggest trying the "creeper and ocelot" method.

One way to do this wold be to have an observer block facing down at the cobblestone which triggers a piston to push the cobblestone when it appears, you have pistons further down that push these lines of cobblestone into a big stockpile, there you can mine it or blow it up.

The "legit" vanilla way is using TNT.

Normally, with a single TNT breaking about 15-20 blocks and costing 4 sand and 5 gunpowder that's not a very viable approach, but there is a way to improve that by a lot: blast chambers.

Blocks while moved by pistons have blast resistance of 0, technically a bug but in practice this issue was addressed by Mojang in snapshots of 1.14, tweaked some, reverted, tweaked in a different way, then left in current state, pending a "proper fix" in indeterminate, distant future.

Yes, it can be removed, but it's unlikely to happen anytime soon, and meanwhile blast chambers work just fine.

The technical community is in an 'arms race' to produce a blast chamber that breaks most blocks per one TNT explosion.

Here's a popular design by Ilmango that breaks 240 blocks per one TNT.

There exist ones

that double or triple that, already.

And if you don't mind exploiting the TNT duplication glitch (most technical players don't), you can get by with a much simpler designs that don't time the motion with the blast perfectly, just happily drop as much TNT as you need, or still utilize the perfect timing and achieve insane drop rates - for example this cobble generator produces 120,000 blocks per hour (over a chest per minute):

It is impossible to break blocks like cobblestone using only redstone or pistons.

However, there are several mobs such as the Wither, Ghast, and the Creeper that can break blocks.

My suggestion for making a block breaking system would be to use these creatures of mass destruction.

Tnt is a good way of breaking blocks, since they explode.

Beware that they can also destroy the blocks too, so it isn't a good way of collecting either.

Question: Is there a way to break blocks with a redstone/piston system and then pick them up with a hopper in vanilla Minecraft. I want to make an automatic cobblestone breaker.  I know that I can break sand, I want to know how to break stone.

How can I make an automatic cobblestone breaker?

You can use command blacks or an observer block. This is not possible in vanilla.

There are plenty ways to destroy automatically cobblestone, such as using tnt.

The community is listing few ways to break cobblestone, automatically.

While few others suggest that it is impossible, by normal means..


Mods are not needed to do this.

You can get all these potions and more with commands.

For a swiftness potion: /give <player> minecraft:potion 1 0

{Potion:"minecraft:swiftness"} For a hunger potion: /give

<player>

minecraft:

potion 1 0

{Potion:"minecraft:hunger"} For a nausea potion: /give <player> minecraft:potion 1 0

{Potion:"minecraft:nausea"}

If you want the effect to be amplified (e.g. Strength 4 or Speed 18 etc),you could use this: /give @p potion 1 0 {CustomPotionEffects:[{Id:(id of the potion),Duration:(number of ticks it should last),Amplifier:(amplifier value)}]}

If you want more than one effect, this also works: /give @p potion 1 0 {CustomPotionEffects:[{Id:#,Duration:#of ticks,Amplifier:#},{Id:#,Duration:#of ticks,Amplifier:#},{Id:#,Duration:#of ticks,Amplifier:#},{...}]}

If the amplifier is negative, it will do the opposite effect.

For example, an amplifier value of -2 on a health potion will reduce your maximum health.

On a Strength potion, it will reduce the amount of damage you deal.

You can just do this command to get nausea potion, and just do the same for hunger but change the 9 to 15. /give

@a potion 1 8256 {CustomPotionEffects:[{Id:9,Amplifier:10,Duration:600}]}

If you want to get a nausea potion, use this command: /give {Player} minecraft:potion 1 0 {CustomPotionEffects:[{Id:9,Duration:100}]}

As you can see my Duration is set to 100 is because by default, it will not last long, so just change the Duration into a higher number to make it last longer.

In 1.13/1.14, it is the following: /give

@p

minecraft:

potion{CustomPotionEffects:[{Id:9b,Amplifier:1b,Duration:1200}]} 1

You can do the command /effect {player} nausea {number of ticks} for hunger (or other potion effect) change the "nausea" part to the effect you desire.

Hunger: "/give

@p

minecraft:potion 1 0

{CustomPotionEffects:[{Id:17,Duration:1000}]}

Nausea: "/give

@p

minecraft:potion 1 0 {CustomPotionEffects:[{Id:9,Duration:1000}]}" Change the "Duration" to make it last longer or shorter.

Question: How do I get the hunger and nausea potions that are unavailable in the creative mode inventory?  I've seen Youtubers doing it but I cannot get them with commands that I have tried.   Is a mod needed to get them? If not how can I get them?

How do I get nausea and hunger potions?

You can get all these potions and more with commands. One example is  /give {Player} minecraft:potion 1 0 {CustomPotionEffects:[{Id:9,Duration:100}]}  for the nausea potion.

In order to get nausea and hunger potions, except crafting, the user will have to use commands.

The community suggests commands to get nausea and hunger potions.


I have found another method, which is a compilation of all the methods I've seen so far.

My goal is never use units to look for other opponents.

I don't use sandbagging anymore.

Battles 1 to 9 -

It should be easy.

Battles 10 to 12 -

I don't use sandbagging.

I just play the lowest 3* teams.

Battles 13 to 19

- I use 3 4* 3/30 From battle 20 and on

I just keep my team total PI over 4200 (with no synergies or boosts).

This is not the fastest method because if you don't have enough teams of 4*s you'll have to wait for their cooldown.

Well, I guess I'll just post what I found on Reddit :

Battles 1 through 8 or 9, easy. 9 through 15, sandbag.

Play 2 champs around the same, and 1 really weak one.

If you get a match up too difficult, pay the credits for a new matchup.

I prefer to use champs that are around 1200 PI each.

16, 17 and 18

, Keep your team PI above 5500.

Typically you need to use 4*s that are 3/30.

If your PI is not above 5500, you will get the monster 14,000 PI teams.

From 19 on, you can drop down, but keep your PI above 4000.

All these numbers are without any buffs active.

If you turn on any buffs, the PI requirements go up.

This should work for the current version 5.0.

It is the best technique I found so far.

this might help as well 1 to 9 you can use your 3stars not ranked up or level up 9 to 12 - use 2 (3star champions that maxed out and must be above 1500pi) and another 3 star champ that is level 1 13-14 use three 4 star champs that should be 3/30 (on this level you will encounter KANGS TEAM or THANOS TEAM) 15-22 use three 4 star champs 3/30 (on this level you will encounter another players still controlled by AI

so be carefull with selecting your champs

make sure they dont trigger will power) 22 to infinity use a team of 4star champs that is 3/30 or maxed out 3starteam should be more than 4500 PI ( by the way on streak 20 to infinity you will encounter enemies that labeled easy but dodges, parry and block like a beast)

Here is the method I use.

fights 1-8 weakest characters or highest 4 stars 9-12 lowest or maxed 3 stars 13-18 4 stars at 3/30 or better 19-infinity 2 4stars + 1 maxed 3 star or 3 3 stars maxed or 2 maxed 3 stars and a 2/20 3star this has gotten me to 100 wins.

I figured it out!

I have successfully done this repeatedly and failed when deviating.

Note that number of battle below is 1 less than win count on screen.

3v3 1-3 stars: 1-8

whatever 9... 3 star max or 3.5k total PI 3v3 3-4 stars: 1-13 whatever.

sand bag if you must (10-12).

14-15 4 star rank 3 or higher.

16... 3 stars max or higher no less than 5k total PI 3v3 1-5 stars: 1-15 whatever.

sand bag if you must (10-16).

16-18 4 stars rank 4 or higher 18... 4 stars rank 3 or higher (mix 2x4 stars rank 1x2) 3v3 4-5 stars:

Sorry I only have 4 star rank 4 and lower.

The requirements are too high for me.

(observation)

It seems to me, when the easiest option is double your total PI is when the infinite starts, but it wont kick in unless you have high enough PI.

Question: I really like Marvel Contest of the Champions, but all the information about this game is on forums. I find that the developers from  Kabam  want to keep some information a secret. And the information on  GameFAQs  is almost always outdated.  So, how do I keep a streak on 3v3 arenas?   Edit Question refers to 4* arenas.

How do I keep a streak on 3v3 arenas on Marvel Contest of the Champions?

1-8 weakest characters or highest 4 stars, 1 to 9 you can use your 3stars not ranked up or level up  9 to 12, 13-14 use three 4 star champs that should be 3/30.

To achieve a streak on 3v3 arenas, in Marvel Contest of the Champions, the player has to figgure out a tactic.

Users explain their tactics to achieve a streak.


Yes, you can.

It is very rare, but Dragonite does spawn in the wild.

I caught one outside my house in the middle of the night, which was pure luck.

Others

I know have had success at local hot spots when there's been a lot of other people around

(there's a widely held belief - perhaps with proof, I'm not 100% sure),

that rarer Pokemon spawn when there's a lot of players in one area.

So, if you'd like a slightly higher chance of finding a Dragonite in the wild, see if you can find a local park where a lot of players hang out.

There may even be a Facebook group of players in your city that you can connect into.

Finally, I don't believe there are any Dratini nests anymore, but Dratinis do often spawn near water, so it might be worth seeing if you can build up to a Dragonite too - especially considering if you find one in the wild, you'd probably want the candy to power it up.

You can catch a wild Dragonite!

I haven't yet, but I've seen a wild Dragonite on my Nearby radar while on the bus.

So you can catch it, but it's very rare to find one, and you'll need luck on your side.

Yes, Dragonites are able to be found and captured in the wild.

As for their rarity... if you go to pokesnipers.com, you will see a real-time list of rare pokemon worldwide and their locations as they are discovered.

Someone recently mentioned how Dragonites used to show up on the list fairly regularly, yet now you can watch the list for a long time and not see even one.

I have yet to see one on the list

and I've been checking for a few days.

Not very frequently, mind you, but a month or two ago I would see one every time I looked at the list.

So, it seems that wild Dragonites may have become rarer... or one just hasn't popped up yet, who knows?

My advice on finding a wild Dragonite is to go somewhere

that is fairly popular with a number of pokestops

Put a lure or two on some pokestops, use an incense and walk around for a bit in the vicinity.

Dratini are found by (large?) bodies of water and dragonites are supposed to have a slim chance of appearing where a dratini has been seen/found.

Dragonites are supposed to have been most commonly reported as appearing near or in parks.

Hope this helps.

Yes you definitely can.

According to rankedboost you can find them in golf courses or near landmarks!

Yes, I caught one at my neighbors house 250 cp.

The IV's were great

so I kept powering it up with dratini, now it's at 2400 cp.

Yes my daughter caught one today at legoland when she caught a snorelax it was in the queue for legends of gaming

so both times lots of people in the same area playing!

She made me screenshot the journal to prove she caught it!

Check Rarity Chart.

I second his statement that pokemon have their respective spawnpoints AS WELL as that each step of the evolutionary line can spawn.

Question: I was just wondering if you could catch a wild Dragonite, because I see them in gyms and it is hard to evolve up to him.

Can you catch a wild Dragonite?

Dragonite does spawn in the wild. They can be found and captured in the wild.

Yes you can for sure, it spawns in the wild.


It's impossible to give a correct AND simple explanation I think.

I would explain it like this if I was asked: The downwash from the wings and the downward component of the wingtip vortices create a higher than normal pressure area below the wings because the air hits the ground and can't "escape", increasing lift.

Induced drag is reduced because wingtip vortices (causing drag) can't fully develop close to the ground.

For a simple and correct answer you need first to understand induced drag.

Please read this answer if you feel unsure.

Short version: The wing creates lift by deflecting air downwards.

Induced drag is the consequence of this deflecting, because the resulting force of this deflection process is tilted backwards by half the deflection angle.

Due to the backward tilt, the force has a horizontal component, pointing backwards.

This is induced drag.

The ground effect will prevent this flow field from developing fully, because air cannot flow into the ground.

Consequently, the deflection angle is lower, and also its horizontal component, i.e. drag.

The same happens ahead of the wing, where the upward motion of air ahead of the stagnation point is also restricted.

Another consequence of this is a reduced lift curve slope in ground effect.

Lift is higher relative to induced drag compared to the free-flow case because the wing somewhat blocks the outflow of air at the trailing edge, and this results in a higher pressure on the bottom of the wing compared to the free-flow case.

This "cushion-effect" explanation is actually quite correct.

The pressure which lifts the airplane is not only created by accelerating air downwards, but also by ram pressure.

This effect disappears once the wing is far enough from the ground.

The ground acts as an aerodynamic mirror.

When the wing approaches the surface it is as if an inverted wing comes from below.

Their high pressure areas amplify each other, increasing the efficiency and thereby reducing the drag.

Here's my simplification, it's not the full story, but it covers the essentials.

Lift:When you are in free space, the high pressure below your wing dissipates into the surrounding air.

When you're in ground effect, the high pressure below the wing encounters an incompressible solid, and therefore cannot dissipate as quick, causing higher pressure below the wing, and therefore more lift.

Drag:When you're in free space, the wake (turbulent, low pressure) behind your aircraft dissipates unimpeded until it becomes uniform with the surrounding atmosphere.

When you're in ground effect, the air near the ground absorbs this dissipation quicker because it has to shear against the ground (more friction that air in free space).

Additionally, wing-tip vortices encounter the ground and dissipate much quicker than in free space.

I suspect the reason GE is tied to wing length is because the longer your wing is, the stronger your wing tip vortices, and the further air has to travel laterally to exit the high pressure zone under the wing.

Simple explanation:

When out of ground effect, air on the bottom of the wing has plenty of room to move around.

When in ground effect, the air on the bottom of the wing can't move around nearly as well and therefore pushes the plane upward to try and make more room.

in normal flight high above the ground, wings create lift by deflecting an air stream downwards.

This is not possible close to the ground: air does not travel through the ground surface.

Picture

the downward air stream being bounced back and increasing pressure underneath the wing.

This happens partially at the wing, not only behind it, because at sub-sonic speeds the air is being split in front of the wing.

So in ground effect, lift is created by pushing air downwards and by increased static pressure underneath the wing, like a hovercraft.

And the increased pressure does not come with an induced drag penalty.

And that is the main difference: total drag is lower in ground effect than in normal flight.

The wing pushes air down.

In flight, that air pushes on other air that moves.

In ground effect, that air pushes on the ground that doesnt move.

Pushing things that move is more difficult than pushing things that dont move.

Like walking on sand vs walking on pavement.

What happens behind the trailing edge is surely irrelevant.

The wing has an angle of incidence to the ground so there is a wedge effect under it, presumably increasing pressure under the forward part of the chord and less so under the after part due to venturi effects.

Looks like a cushion effect to me and the airflow over the wing is deflected, and pressure reduced, as it would be at altitude.

Question: We've all heard the "acts like a cushion of air" explanation tossed casually around by CFIs.  There's also plenty of books and reference materials that give a detailed, accurate, and complete explanation of ground effect, and which are incomprehensible to most student pilots.  What's the simplest way to accurately explain ground effect?

What is ground effect?

The downwash from the wings and the downward component of the wingtip vortices create a higher than normal pressure area below the wings because the air hits the ground and can't "escape", increasing lift. Induced drag is reduced because wingtip vortices (causing drag) can't fully develop close to the ground.

It is a complicated topic, however here is a simple answer, when close to the ground the air below the plane has little space to move, pushing the plane upwards.


This is actually a really hard question to answer, as there are a ton of factors.

I'll try to cover a few.

Visibility is probably the reason you most hear when it comes to GA pilots.

High-wing aircraft offer better visibility below the aircraft, especially for passengers in 4-seat or larger aircraft, as the wing doesn't block it.

Low-wing aircraft can offer better visibility above the aircraft, as the wing remains mostly out of the field of view.

Note that a lot of midair collisions involve mixed types; low-wing aircraft descend into high-wing, or high-wing aircraft climb into low-wing.

Landing characteristics are different, as low-wing aircraft can incur more ground effect than high-wing.

Aerodynamic stability of the two designs differs a bit; the center of lift can be higher in a high-wing design, often offset with dihedral in low-wing aircraft.

Ground clearance (and debris protection), specifically in multi-engine aircraft, is going to be greater when engines are mounted on a high wing rather than a low wing.

This is true of both propeller and jet engines, although propellers tend to have a larger radius for a given aircraft size.

There are a bunch more, but that ought to get the argument discussion going.

@Egid, your already gave really good and correct answer dealing with the most important benefits and downsides, or simple the most significant differences.

I like to follow your invitation and add the differences I thought of and you have not already mentioned:

The additional ground clearance also benefits the maximum crosswind some high-wing aircraft can cope with, what in my eyes is also an important point.

Also high wing aircraft - talking about light sports - benefit the design of the fuel system as it allows consumption from both tanks simultaneously without installation of additional fuel pumps

- this is not only a benefit for lazy pilots but has probably already prevented some accidents.

Now somebody needs to tell me why I'm flying low-wing ;)

Low wing aircraft also benefit that in a crash, much of the crash energy can go into the wings instead of into the fuselage.

Low wing aircraft have the advantage in a water landing because the wings can keep much of the fuselage above water, as well as provide a temporary staging area for deplaning passengers.

In a high aircraft, you would be lucky to get out before drowning.

Likewise, on land, low wing aircraft are easier to control in a wheels up landing.

Low wing aircraft can be designed with a more widely spaced and shorter main gear, which is more stable.

Most high wing aircraft use fuselage sponsons (MU2, ATR-42/72, Do228/328, BAe-146/Avro RJ, C-130) to house the main gear, providing a relatively narrow, and therefore, less stable track.

For those high wing designs that house the main gear in wing-mounted engine nacelles or in the wings themselves (Twin Commander, F-27/227, Dash 7/8, B-24/32), the gear must be made much longer, and therefore, much heavier.

A long main gear design is also more prone to structural failure in a hard or poorly executed crosswind landing.

Low wing aircraft are easier to refuel, and if equipped with wing-mounted engines, those would be easier to service.

Here are a couple of ground comfort related differences.

When it's hot, and you're waiting in line for fuel, or if your plane isn't hangared, you can stand in the shade under a high wing.

If you want to walk from fore of the wing to aft of the wing, to get the oil rag you forgot, with a high wing, you duck a bit and walk straight, with a low wing, you walk all the way around the wing.

Twice.

Another factor is fuel flow (at least in small GA planes).

Lets compare a Cessna 172 to a Piper Cherokee.

The Piper is low wing and requires a fuel pump (engine driven with an electric backup) to flow the gas from the wing tanks up to the engine.

This add not only adds another part that can fail but the possibility that you can vapor lock the system if you run it dry.

In a the Cessna (high wing) the fuel is pulled by gravity, out of the wing tanks, and into the engine much like an old car (1930's era).

This eliminates the fuel pump and the vapor lock issue which some people find quite nice.

At this point I am well into the habit of switching tanks every 30 minutes.

A note should be made that some Cessnas (from what I have read) do have fuel pumps now

but I don't fly them

so I don't know a lot about the newer model specifics.

High wing airplanes also prove to be advantageous if you are flying a lot of back country stuff.

The added clearance can help you land in bushy areas or other less hospitable places where a low wing plane might strike something.

The best answer to this question can usually be found at your local airfield.

Ask a guy that owns a Piper (just not a Cub), then ask a guy that owns a Cessna (just not the 400), and decide for your self based on their answers.

Another factor with low-wings is that on take off and landing, the low wing will block airflow over the empennage, reducing rudder and elevator effectiveness.

That's why so many low-wings have T-tails, to keep the tail in the flow of air during landing and takeoff.

A quick addition to the previous answers:

Larger commercial aircraft also capitalize on the low-wing's benefits from a maintenance perspective.

Let me add one more advantage/disadvantage pair.

High-wing aircraft (at least for small GA aircraft) may be easier to preflight as wing fuel drains are more accessible and it is easier to examine the underside of the wing (flap linkages, aileron hinges, skin, possible fuel leakages).

Personally, I'm tall enough to be able to see the top of the wing without a ladder, but I'll admit that this advantage shrinks for shorter pilots.

The downside is ease of refueling (and sticking the fuel tanks).

A Cherokee (low-wing) doesn't require a ladder to refuel whereas we carry a stepladder in our club Cessnas.

Question: What are the advantages and disadvantages of a high-wing vs. low-wing aircraft design? When might one prefer one to the other?  Is the answer the same for large and small aircraft?

What are the pros and cons of high-wing compared to low-wing design?

There are a lot of different factors. Visibility  is probably the reason you most hear when it comes to GA pilots. High-wing aircraft offer better visibility below the aircraft, while low wing aircraft have the advantage in a water landing because the wings can keep much of the fuselage above water.

While this is a hard question to answer due to the factors involved, it is generally agreed that high wing aircraft enjoy a little more visibility towards the ground, a little more ground clearance, less ground effect, less cross wind and offer a place to take shelter from sun in hot climates. On the other hand, low wing aircraft have an advantage in crash landings as much of the force goes into the wings instead of the fuselage, and have better visibility above.

Disclaimer
High wing aircraft characteristics
Low wing aircraft characteristics


Not a real example, but this comes from the FAA , including some nice drawings around page 13-20: The emergency extension system lowers the landing gear if the mainpower system fails.

There are numerous ways in which this is donedepending on the size and complexity of the aircraft.

Some aircrafthave an emergency release handle in the flight deck that is connectedthrough a mechanical linkage to the gear uplocks.

When the handle isoperated, it releases the uplocks and allows the gear to free-fall tothe extended position under the force created by gravity acting uponthe gear.

Other aircraft use a non-mechanical back-up, such aspneumatic power, to unlatch the gear.

The popular small aircraft retraction system ..... uses a free-fall valve for emergency gear extension.

Activated from the flight deck,when the free-fall valve is opened, hydraulic fluid is allowed toflow from the gear-up side of the actuators to the gear-down side ofthe actuators, independent of the power pack.

Pressure holding thegear up is relieved, and the gear extends due to its weight.

Airmoving past the gear aids in the extension and helps push the gearinto the down-and-locked position.

Large and high performance aircraftare equipped with redundant hydraulic systems.

This makes emergencyextension less common since a different source of hydraulic power canbe selected if the gear does not function normally.

In some small aircraft, the design configuration makes emergencyextension of the gear by gravity and air loads alone impossible orimpractical.

Force of some kind must therefore be applied.

Manualextension systems, wherein the pilot mechanically cranks the gearinto position, are common.

Consult the aircraft maintenance manualfor all emergency landing gear extension system descriptions ofoperation, performance standards, and emergency extension tests asrequired.

The rulebook for transport category aircraft says 14 CFR 25.729 c)

Emergency operation.

There must be an emergency means for extending the landing gear in the event of— (1) Any reasonably probable failure in the normal retraction system; or (2)

The failure of any single source of hydraulic, electric, or equivalent energy supply.

The F-16 has an "emergency blow-down" reservoir containing approximately 3,000 psi gaseous nitrogen.

Hitting a switch will release this pressurized nitrogen into the hydraulic system dealing with the landing gear.

Ergo, hitting that switch will extend the gear, even with the engine off.

So

yeah, the landing gear will still work in the event of a complete power failure.

It has backup systems.

In the older A-4 Skyhawk, the landing gear retracted up and forward.

So, in the event of a hydraulic failure, if you could get the gear doors open, the airflow past the aircraft in flight would "drag" the gear down and aft and lock it into position.

I think that's a pretty slick design.

Almost all aircraft have some sort of backup system for getting the gear down.

On the planes I have owned they were: Manual hydraulic pumps to pressurize the system with a car jack type handle.

You sort of pumped the gear down.

Obviously does not work too well if the problem with gear system is a no fluid (blown line or seal).

Mechanical crank (21 turns to get down, 2 more to lock) that drove the gears if the electric motor died.

Good workout.

The Twin Comanche I used for my AMEL rating had an interesting mechanism.

First you had to disconnect the electric motor, then you stuck this handle into a hole and crank it as far as you can.

Then you shift it to a second hole (that becomes usable after the first one is used) and crank on it again until it stops.

Not something you get to try until you need it though.

Once you pull the disconnect it requires an A&P to restore the system to normal operation.

All aircraft have some kind of backup system.

As mentioned before-

Skyhawks Landing gear gets sucked down.most of the other planes-

just fall down thanks to gravity.

A lot of the airplanes (including military and some civilian)- have a handle to open the bays mechanically (like in the 737) and the gear falls down and locks automatically with a mechanism that is independent of all hydraulic or electricity.

As for the big jets- they have an amazing amount of backups.

And still- if in a 787 all your computers catch fire for some reason-

probably you wouldn't be able to extend your gear.

But then- even flying the plane would be a challenge, as the aircraft needs voltage for everything.

In this case, there is another backup for flying the plane using a special connection of direct wires from the stick to the flight control surfaces, powered by backup generators.

It all depends on the airplane in question.

Typically for small GA airplanes using an electro-hydraulic power pack for actuating the gear

, they’re held retracted by hydraulic pressure.

If the system fails, the pressure goes to zero and the gear just drops down due to gravity.

I have time in the DA-42 and DA-62 twins and those airplanes

use an alternate gear extension handle - basically an emergency valve which releases hydraulic pressure and allows the gear to drop down on their own.

Electrically powered landing gear can be typically lowered by means of a hand crank in the cockpit.

This is prominent on Mooneys and light Cessna twins.

Larger airplanes and jets may make use of emergency reservoirs of compressed nitrogen called blowdown bottles to provide emergency hydraulic pressure and extend the gear.

Typically the landing gear retraction jacks can be isolated from the main hydraulic system via a cockpit switch to prevent total loss of hydraulic fluid in the event of a leak.

It also removes the additional workload from emergency systems eg APU, RAT, etc. for more critical flight control functions.

Transport category airplanes often have multiple layers of redundancy ie multiple hydraulic systems and power sources to get the plane down safe.

Question: In case of a total power failure in all the aircraft systems like engine failure and APU failure, would it be possible to use mechanical means (manually) to open the landing gear bay door and deploy the landing gear through mechanical means?  I know it’s possible to glide the flight if the engines failed. But, wondering how they land.

Will the landing gear work mechanically in case of total power loss?

Almost all aircraft have some sort of backup system for getting the gear down.  Typically for small GA airplanes using an electro-hydraulic power pack for actuating the gear. Electrically powered landing gear can be typically lowered by means of a hand crank in the cockpit.

There is usually a system that lowers the landing gear in an emergency. There can be an electrohydraulic pack, or a hand crank in the cockpit. Some bigger plans also have an emergency reservoir of compressed nitrogen for that job too.

Users suggest different ways with which the gear can be lowered in an emergency


After doing a little more research I found the answer.

The zig-zag on the leading edge is a type of leading edge extension called a dogtooth extension .

Quote from wikipedia:

A dogtooth is a small, sharp zig-zag break in the leading edge of a wing.

It is usually used on a swept wing, but also on straight wings ("Drooped Leading Edge" arrangement), to generate a vortex flow field to prevent separated flow from progressing outboard at high angle of attack.

The effect is the same as a wing fence.

Where the dogtooth is added as an afterthought, as for example with the Hawker Hunter and some variants of the Quest Kodiak, the dogtooth is created by adding an extension to the outer section only of the leading edge.

As already answered, the zigzag is a dogtooth extension or leading-edge extension on the outboard portion of the wing.

It forces the airflow over the wing into a vortex, preventing spanwise flow outward along the wing at high angles of attack.

A lot of modern designs incorporate them, including the horizontal tail of the F-15 Eagle, because they often have a side benefit of increasing airflow over the ailerons and increasing control.

To answer the second part of your question ( why do only some Hawker Hunters have this feature? ):

the dogtooth extension wasn't incorporated into the design until the F.6 variant.

Wikipedia's list of Hawker Hunter variants mentions it in a couple of entries.

Basically, the earlier models didn't have it; at some point the designers and aerodynamicists working on the Hunter tested it out.

Once they figured out that it was an improvement, they would have made the necessary changes to the production line to make it standard on all late-model aircraft built.

Cirrus incorporates this design into their wings as well.

Quoting from their site : The outboard section of the Cirrus wing flies with a lower angle of attack than the inboard section.

When the inboard section, which produces much of the lift, stalls the outboard section, where the ailerons are, is still flying.

The result is that a stalled Cirrus airplane can be controlled intuitively using aileron.

Update : The hawker hurricanes wings are better describes as dogtooth extension as flyingfisch points out.

These features are known as a Leading edge cuff and aims to reduce spin tendencies by delaying the onset of stall.

As an added piece of information, this feature may have something to do with the fact that the Hawker Hunter, for many years, was the only swept wing fighter that could be reliably recovered from an inverted spin.

For this reason the Empire Test Pilot School at Boscombe Down used one for advanced training purposes (and may still do so).

Question: On some  Hawker Hunters , there is a zig-zag on the leading edge of the wing, as shown below.   Why do only some Hawker Hunters have this feature, and what is it for?

What does the zig-zag pattern on Hawker Hunter's leading edge represent?

A dogtooth is a small, sharp zig-zag break in the leading edge of a  wing. It is usually used on a swept wing, but also on straight wings

The zig-zag is called a dogtooth extension or break in the leading edge of the wing.


Technically yes.

But I am unaware of any attempt to do this with airliners.

But there were several designs in the past which used a big airplane or a Zeppelin as a mother ship, which took fighters with it for air defense.

The B-36 was involved in several such designs.

In all cases the docking was made from below, because this gave the fighter pilot the best field of view and reduced the risk of a tail strike.

While the fighter in the picture above is a Republic F-84, McDonnell even designed one specifically for the purpose of being carried around by a bomber, the XF-85 Goblin .

It used a rather complicated trapeze for docking and was then pulled up into the fuselage, as the picture with a B-29 below shows.

Your design proposal with the simple platform on top of the fuselage would carry a high risk of a tail strike if anything goes wrong, so it is unlikely that this will ever be tried for real.

But when you change the airliner to a AN-225, the idea looks not totally impossible.

The Russians tried to dock a fighter with a mothership as early as the 1930s.

The picture below shows a TB-3 docking with a I-Z fighter, the first pair of aircraft in history to dock in flight.

The main reason for docking was the much smaller range of fighters.

Today, air refuelling takes care of this deficit, so it is unlikely that anyone will see a benefit strong enough to justify the expense of modifying two aircraft and the risk incurred in the docking process.

Parasite jet aircraft have been experimented with, the only purpose built one I know of is the XF-85 Goblin , there was also a modified F-84 Thunderjet which was used as well.

These experiments were abandoned because the process of launching and recovery was too hazardous, and air to air refueling made much more sense to extend the range of fighters.

It is possible to join 2 aircraft in the manner you describe, however it's extremely dangerous due to the aerodynamic forces involved, and there are no benefits which would make the risks worthwhile.

It is not possible to replicate this process safely.

The pilot in the smaller aircraft can not see its gear and would have no idea where to "land".

And perhaps even more importantly, there's no out if the fighter has an emergency.

If the fighter loses control just above the carrier then its likely that both aircrews will die.

As has been pointed out in other posts, aircraft have been recovered underneath carrier airplanes in the past, and while dangerous, this leaves an obvious escape route in the event of an emergency.

DARPA just happens to be asking for proposals on how to accomplish this very task: DARPA invites input on how to enable existing large aircraft to carry, launch and recover multiple unmanned air systems for a variety of missions

As an addition to the projects described by Peter Kämpf, there was the Tip Tow project during the fifties where two fighters were attached to the wingtips of a B-29.

The idea was that the additional wingspan would increase the range of the bomber, while at the same time enable it to carry its own fighter escort which could attach and detach in the air as required.

While attached the fighters could switch off their engines, thus saving fuel for later.

While attached, the B-29 would control the flight surfaces of the attached F-84 (more specifically EF-84D) so that the pilot wouldn't have to do this manually, but during the first flight with this system enabled one of the fighters rolled on top of the B-29s wing, and the two aircraft crashed with no survivors.

The second F-84 survived as it was disconnected from the B-29.

Question: Imagine this scenario:  A modified military 747 is flying at a constant speed and altitude. On the top of the fuselage there is a device like a helipad but with three holes to accommodate the fighter jet landing gear, when pressure is applied the holes close, locking the landing gear in the holes. The fighter is flying at the same speed and slightly above. With proper training, is it possible for the pilot to land on the plane and then shut off the engines?

Can a fighter jet land on a modified airliner?

It is possible for a jet fighter to land on an airliner but it is extremely dangerous. DARPA, however, is looking for proposals to perform exactly this task.

There are examples of this being attempted in the past. In the 1930s, the Russians attempted to dock a fighter with a mothership. Experiments have also been conducted with parasite jet aircraft. However, although this process is technically possible, it would not be safe and the risks far outweigh the benefits. Interestingly, DARPA is currently requesting proposals for ways in which this action could be achieved.

Although this process is technically possible, it would not be safe and the risks far outweigh the benefits.

There are examples where this has been attempted. In the 1930s, the Russians attempted to dock a fighter with a mothership. Experiments have also been conducted with parasite jet aircraft.


Why do airliners have them?

Because passengers like them.

When you're sitting in the penalty box waiting for a departure slot and the air conditioning system is barely running the extra cool air you can get from those vents may be the only thing keeping passengers from strangling the screaming child kicking the seat.

Also a common "cure" for airsickness is fresh air -- blowing cool air over someone's face will often help with symptoms of motion sickness, and may prevent a nauseous passenger from actually vomiting.

Opening these overhead "gasper vents" and directing them at the passenger's face provides a quick way of doing this.

The airjet openings are connected to a long duct running along the ceiling.

Since the air volume inside the cabin is restricted, fresh air must be pumped into it constantly.

It is bleed air from the compressor section of the engine, which is first cooled and then enters the cabin via those ducts which feed all the little vents or airjets, as you call them.

Passengers can open or close them individually and direct the flow for best comfort.

The general idea is that some vents will be closed, but enough are open during every flight so the needed recirculation of air can happen.

If more are closed, the pressure in the duct will be higher, so the flow through the remaining vents will increase.

The total weight of all the cabin ducting is a minor consideration, it's only a few dozen gram per passenger.

The primary reason is that not everyone likes the same temperatures.

I happen to be cold-natured and like to be warm.

Other people are hot-natured and like to use copious amounts of air conditioning.

These allow all of us to stay relatively comfortable in the same cabin.

Also, when you're sitting on the ramp in the summer, it's more than 100 degrees Farenheit outside, and the boarding door is still open, you'll learn to appreciate these things quickly, especially if you've been standing in the jetway a while before taking your seat.

Personally, I usually turn mine off during flight, but I do tend to use them on the ramp and sometimes during taxi in the summer and/or unusually hot climates.

Lowest cost is king if you can get away with it.

Personal air vents provide more flexibility than if they were absent and the overall cost is lower.

If personal airjets are available then the jet temperature and maximum available flow can be set to suit people with preferences on the cold side of normal, while the mean temperature can be hotter than would suit a significant proportion of people.

If, instead, the cabin needed to be maintained at a temperature that most people would consider acceptable then, in the absence of personal vents, the whole cabin would need to be cooled to that temperature.

Some people would then feel too cold, which can be dealt with by clothing or blankets, and most people would be comfortable.

In the first case you have lower than otherwise energy use with "outliers" being addressed with airjets.

In the second case you have higher than otherwise energy use with outliers being addressed with blankets.

The energy cost of the blankets is zero but overall it still costs more this way.

FWIW

I'm an air-jet loving traveller and greatly dislike aircraft without them.

Although probably not the primary reason airlines have them in the first place, there is another great reason to use them.

Having fresh "outside" air blow in front of you displaces the viruses/bacteria/etc.

from sick passenger's coughs and sneezes away from entering your nose and mouth.

Make the passenger feel

he's in control of something.

The practical use is to fight rising temperatures and odors, but i also quite like the oxygen.

Question: I never turn them on, but I do turn them off if I notice them. Is this a relic from the age when people lit up next to you and you wanted to blow away the smoke? The system must weigh almost a ton on a large aircraft and seems pretty unpopular and hard to maintain.

Why do passenger aircraft have the little airjets over each seat?

The primary reason seats have airjets on planes is that not everyone likes the same temperatures. Personal air vents provide more flexibility than if they were absent and the overall cost is lower. If personal airjets are available then the jet temperature and maximum available flow can be set to suit people with preferences on the cold side of normal, while the mean temperature can be hotter than would suit a significant proportion of people. Also a common "cure" for airsickness is fresh air -- blowing cool air over someone's face will often help with symptoms of motion sickness, and may prevent a nauseous passenger from actually vomiting.

The vents are there for the comfort of the passengers. People like different temperatures and the vents accommodate people who like cooler temperatures as well as those who like warmer temperatures. Fresh air can also help with air sickness and may stop a nauseous passenger from vomiting. Another reason is that the vents help to recirculate the air during a flight. In terms of weight, the cabin ducting only amounts to a few dozen grams per passenger so this is not a significant consideration. Individual air vents also provide greater flexibility and are cheaper.

They help to recirculate the air during a flight.

The cabin ducting only amounts to a few dozen grams of weight per passenger so this is not a significant consideration.

Individual air vents provide greater flexibility and are cheaper.


I understand where you are at with this, I'm going to start off with a bit of math to show how it's not workable.

Commercial airliners move quickly, even in a controlled glide one is going close to 3 miles (4-5 km) per minute.

To give people on the ground enough useful warning to perhaps find some sort of cover you would need to give at least 20 seconds.

This siren would have to be able to penetrate the walls of buildings and houses and cut through the background noise of a built up area at least a mile ahead.

This is a very powerful siren and you'll have the following challenges:

At close range you would deafen anyone nearby, injuring the people you are trying to warn

The mechanism to generate this siren would likely be large, heavy, and challenging to design into an aircraft frame

You would need a great deal of mechanical or electrical power to generate that amount of noise.

If you have no engine power you won't be able to sound the siren, and if your engines are working you won't need to as the engines make very good sirens

already There are very, very few cases where a siren such as this would save very few lives compared to justify the costs.

No they don't.

If you think about it, it is very rare for an aircraft to crash into a built-up area.

People on the ground would have very little time to hear a siren from an aircraft approaching at a hundred miles per hour or more.

Anyone hearing it might be as likely to run into the path of the aircraft rather than run away from it.

No they don't, crashes over land where the plane was stable enough to provide enough warning to the people on the ground are very rare.

The only incident that would have benefited from it which comes to mind is the gimli glider .

No, and even if they did you would probably not hear it.

Engine noise should be enough to alert someone who is paying attention, but the truth is that the average pedestrian has no cognizance of unusual noises.

Also, the odds of hitting a pedestrian are extremely remote.

Most people move around in cars.

Unless you are landing on a park or a beach there will generally be noone around.

I did hear of one case a couple of years ago where a guy ran out of fuel and landed on a beach and killed a jogger.

The jogger didn't hear him because he was wearing headphones.

When you come down it all happens really fast.

A pedestrian, even with a lot of warning would have to be paying attention, be alert and react right away.

Most people are absorbed in what they are doing and a siren going off 1000 feet away and 300 feet up is not going to be on their radar.

They did design one plane with a siren to warn people on the ground.

The aircraft was called the "Stuka"The pilot would diligently turn on the warning siren right before he nosed down and dove at 300 miles per hour to accurately release his bombs onto the people he was warning.

The warning siren terrorized the general public, so they stopped using it out of consideration for the bomber pilots, who didn't like getting shot down by the military employed to protect the public.

Question: The recent crash of a Taiwan aircraft, got me thinking, do aircraft have built in siren, which can warn people on the ground of a possible crash to give them some headway.  If that is not practicable or feasible, then what solutions are feasible, or one should abandon the idea altogether and think of making planes safer in the first place?

Do aircraft have siren to warn public in case of a crash over land?

Planes do not have sirens to warn people on the ground when they are going to crash, however, the engine noise should alert them. Even if they did have sirens, people probably would not hear them and, if they did hear them, the plane would be coming down so fast, they would have little time to escape. Fortunately, planes do not often crash over built-up areas.

No, aircraft do not have sirens. Aircraft crashes in built-up areas are very rare and when they do occur, it is very rare that the plane would be able to provide enough warning to anyone nearby. When an aircraft is going to crash, it is moving very fast and there would not be enough time for the people on the ground to hear a siren and take action. Moreover, if the engines are not working, they make a lot of noise and this should be sufficient to alert anyone listening, although the average pedestrian would not be listening out for unusual noises.

If the engines are not working, they make a lot of noise and this should be sufficient to alert anyone listening, although the average pedestrian would not be listening out for unusual noises.


Generally yes, but not always.

If you include the APU as an engine, the answer would need to be different, but I understand your question concerns just the engines used for propulsion.

For jets, the direction of rotation doesn't make much of a difference, so the same engines can be used on all stations.

However, with propellers the swirl does influence flying characteristics, especially at low speed, so special left- and right turning versions of turboprop and piston engines are available.

Maintenance and logistics become much simpler if only one type of engine is used.

In the past, not so much emphasis was placed on this, so some airplanes used different types of engines.

Examples were: Convair B-36B , which combined piston and jet engines in the same airframe Junkers G-38 , which used a Junkers L88 inboard and a Junkers L8 outboard.

Later, the outboard engines were also changed to the L88.

This can be seen from the number of propeller blades: If the outer engines drive a two-bladed propeller, it is the earlier version with the L8.

Hawker-Siddeley Trident 3 , which was almost a four-engined jet, because it had a small, tail-mounted RB-162 engine in addition to the three tail-mounted RB-163 Spey to provide thrust on takeoff.

Rutan Voyager , which used a bigger front and a smaller rear engine.

The place to find the true answer is in the Type Certificate Data Sheet.

This document will tell you exactly what engines can be installed on an aircraft.

For example on the DC-10-10: 3 General Electric CF6-6D, CF6-6D1, CF6-6D1A, CF6-6K or CF6-6K 2 Turbofan Engines.

(CF6-6D and CF6-6K engines may be intermixed in accordance with Appendix XXII of the applicable FAA Approved Airplane Flight Manual.

CF6-6D1 and CF6-6D1A engines may be intermixed in accordance with page 2.1 of Section IVB of applicable FAA Approved Airplane Flight Manual.)

As this image shows the Navy flew a plane with two propeller engines and two jet engines.

Read more about it here.

From wikipedia:

Beginning with the P2V-5F model, the Neptune became one of the first aircraft in operational service to be fitted with both piston and jet engines.

The Convair B-36, several Boeing C-97 Stratofreighter, Fairchild C-123 Provider, and Avro Shackleton aircraft were also so equipped.

To save the weight and complexity of two separate fuel systems, the jet engines on the P2Vs did not burn jet fuel-

they burned the same fuel as the piston engines: 115–145 Avgas.

The jet pods were fitted with intake doors that were kept closed when the J-34s were not running to prevent them from windmilling, allowing for economical piston-engine-only long-endurance search and patrol operations.

In normal U.S. Navy operations, the jet engines were run at full power (97%) to expedite and assure all takeoffs, then shut down when the aircraft reached a safe altitude.

Also, the jets were started and kept running at flight idle during low-altitude (500 feet during the day and 1,000 feet at night) anti-submarine and/or anti-shipping operations at sea as a safety measure in case one of the radials developed problems.

Usually the Engines on the same plane are of the same model (or type).

As mentioned in an answer earlier the rotation direction of jet turbines doesn't affect handling, however, the engines installed on either sides must have same thrust as to make the handling easier.

One example for differing engines however is A380, where the inboard engines are equipped with thrust reverser and outboard engines don't have them.

There are several reasons for doing this, not having thrust reverser makes engine comparatively simpler to build and maintain.

The "Super 27" replaced the outer engines of the Boeing 727.

The problem with re-engining a trijet is the necessity of re-engineering the center engine's casing and intake, wspecially if an S-duct is involved.

That is so complicated that re-engine plans typically left that engine alone .

So it was with the Super 27 with a swap to the more powerful JT8D-217.

I have jeard of schemes to put even more modern engines on the outer pylons, but cannot find the link.

aviation.stackexchange.com/users/22864/Harper - Reinstate Monica

Question: In general, are there any differences between the engines on a multi-engine aircraft? Are engines designed to be specifically for the left or right wing, or inboard or outboard for a 4-engine aircraft?  What about the tail engine on a tri-jet like the DC-10? Is it the same as the two wing-mounted engines?

Are all the engines on a multi-engine plane the same?

Most jets have the same engines on all stations as the rotation does not make any difference. However, the A380 has inboard engines equipped with thrust revereser and the outboard engines are not. The place to find such info is Type Certificate Data Sheet.

The engines on a multi-engine plane are usually the same. As the direction of rotation doesn't tend to make a difference on jet turbines, the same engines can be used. However, the engines are not always the same. The A380 is one example of a plane with different engines.

The engines on a multi-engine plane are usually the same, but not always.

The Type Certificate Data Sheet is the best place to look for an answer.


If you are talking about externally carrying/deploying other aircraft, this has already been done with the B-52 (albeit for testing purposes) carrying the X-15 .

I'm not too sure about having an aircraft drop out of a cargo bay such as the C-130.

On a side note military gliders were used extensively during WW2 and some were capable of carrying light tanks.

The gliders were usually towed behind larger bombers to give them the required altitude and speed.

They were used because of their wooden construction allowing a stealthy approach due to the reduced radar signature.

Parasite aircraft is a concept that has been considered.

During the era of the zeppelins several countries experimented with launching fighter aircraft from airships, mainly as a way to get the fighter crafts to a relevant altitude while conserving fuel.

However none of these projects where realized before the end of WWI.

During WWII soviet used Tupolev TB-3's to carry I-16 dive bombers, a culmination of experiments started during the 1930's.

Some of Japan's kamikaze crafts where also launched as parasite aircraft.

In an escort role Germany experimented with parasite craft solutions as a way to bypass the very short operational range of rocket powered fighters, but these experiments where ultimately judged unsuitable.

The extreme range of US strategic bombers in late WWII and early cold war lead US to consider parasite fighters as an escort solution.

However these attempts where eventually scrapped in favour of aerial refueling, as this was considered a safer option.

Source: https://en.wikipedia.org/wiki/Parasite_aircraft

small fighter jets with limited range could be dropped off by large airplanes with very long range That sounds like a one-way mission.

Some Zeppelins and some US Navy airships did carry small aircraft that could be both launched and, importantly from the pilot's perspective, recovered in mid-air.

However in the modern world, the approach you describe is not used.

If fighters are needed beyond normal operational range of their bases, air forces will either use in-flight refuelling or create a forward operating base nearer the mission target.

Aircraft carriers are a popular solution to this requirement, if adequate time is available.

Since your question is about the tech, it very much does exist in a few forms at least for aircraft of varying size.

The Bell X-1 (the plane that broke the sound barrier) was a mid flight deploy from a B-29.

This was a result of its low fuel load

it could not really get its self off the ground and then have enough fuel to break the sound barrier.

This became common for a lot of the high speed test crafts developed over the years.

Up through the X-15 (the fastest thing out there)

The first space shuttle tests were done by flying the shuttle to altitude on a modified 747 and deploying it for an unpowered decent so the tech is there even for large craft.

The more modern Space Ship One also uses this configuration to get it to altitude easier.

The tech is there and has been used over the years.

Now to the more realistic question "would you do it" most likely

no.

As you mentioned there is a case for small limited range planes being deployed at distance but the simpler solution to that is a mid-air refuel .

This accomplishes the range extension and allows the plane to get back home.

The other option is a drop tank which also extends the range of a plane.

Note:

Another kinda of cool solution to the problem was to weld 2 planes into one like the North American F-82 Twin Mustang .

This would be very good from defense point of view, where small fighter jets with limited range could be dropped off by large airplanes with very long range.

Parasite aircraft as a way of increasing the range of fighters has been tried repeatedly, with everything from airships to heavy bombers as the mothership.

It turns out to be much harder than it sounds, and has generally been abandoned in favor of dedicated tankers and mid-air refueling.

Germany had some (very) limited success in WWII with the Mistel concept, which is basically the opposite of what you mentioned: The smaller of two craft was the piloted one, the bigger craft being an explosive-carrying drone -- like a really big glide bomb.

The most common combination was a Fw-190 figher/bomber carrying a Ju-88 drone.

where a large plane can carry a small plane (or multiple small planes) and drop it midair where the small plane deploys itself In addition to those concepts, let us not forget the Goodyear Inflatoplane , which was designed specifically to be dropped from aircraft, inflated, and flown away.

Designed for pilot rescue, the idea of dropping an aircraft in and flying it out was revealed to be ultimately impossible when one considers pilots in a Vietnam jungle.

Question: Is there any present technology where a large plane can carry a small plane (or multiple small planes) and drop it midair where the small plane deploys itself? This would be very good from defense point of view, where small fighter jets with limited range could be dropped off by large airplanes with very long range.

Can small airplanes be towed (or carried) as cargo to be dropped at some other location by air?

The technology exists for large planes to carry small ones. It has been used in the past by Germany, Japan, Soviet Union and the first space shuttle tests. During the Zeppelin era, several countries experiemented with launching fighters from airships.

In terms of technology, the concept is feasible and there have been experiments with parasite aircraft in the past. However, the easier alternative for aircraft with limited range is to refuel mid-air.

There have been experiments in the past with parasite aircraft.

In terms of technology, the concept is feasible.

For aircraft with limited range, the easier alternative is to refuel mid-air.


Acrobatic is being incorrectly used, although it is slightly more complicated than that.

"Aerobatic" refers specifically to flight, and "acrobatic" refers specifically to feats of the human body, so referring to an aircraft as performing acrobatics is wrong.

That said, the word "aerobatic" is derived from "aero-acrobatics" and sounds nearly identical, so it's an understandable and relatively common error.

The Oxford English Dictionary's etymology for "aerobatics" is "After acrobatics " and defines it as: Feats of expert aviation, performed esp.

for display.

Hence aeroˈbatic a .; ˈaerobat , one who performs aerobatics;

hence as v. intr .

, to perform aerobatics; also trans .

So it's a new word pertaining to aviation based on one for (also Oxford English Dictionary): A rope-dancer; a performer of daring gymnastic feats and evolutions; a tumbler. lit .

and fig .

Edit: Notice the fig. at the end of the definition (which is an abbreviation for figuratively ).

So "acrobatic" can correctly be used to describe a person, cat, airplane , etc ... performing "acrobatics".

Some of the other answers seem to claim that acrobatics would be incorrect when used to describe aerobatics, however when you look up various definitions you will find out that acrobatics : difficult and dangerous acts done by an acrobat; also : difficult or dangerous acts, movements, etc., done by another kind of performer Source: http://www.merriam-webster.com/dictionary/acrobatics

So, acrobatics is just the generic word, whilst aerobatics is the more specific word describing a very specific form of acrobatics: acrobatics in the air flowing from the following etymology: aer-

+ acrobatics =

aerobatics Source: http://www.merriam-webster.com/dictionary/aerobatics

So in conclusion it's fine to use either term, especially when it's already clear that the context is about aviation.

In an undefined context it might however be useful to have two words, for example I went to an aerobatics display and

I went to an acrobatics display of course hold two very different meanings.

Point is just: If you can pick, pick aerobatics, but don't go correcting people who aren't saying anything wrong.

In my opinion, acrobatic is more related to a person, "One who is skilled in feats of balance and agility in gymnastics".

However, aerobatic relates to maneuvers on the air.

“Aerobatics” is only a portmanteau of “Aeronatical Acrobatics” either is fine and anyone who corrects you is a word snob.

Question: I hear and read both the terms "aerobatic" and "acrobatic" used to describe the more extreme maneuvers such as spins, rolls, loops and more. My questions is about the terms themselves. It seems that they are interchangeable, but is one actually more correct to use than the other? Why do we have these two very similar words in the aviation vernacular that seem to mean the same thing?

Is there a difference between "aerobatic" and "acrobatic" flight?

Acrobatics refers to feats of the human bosy. Aerobatics refers specifically to flight, it is the shortened version of Aeronautical Acrobatics.

There is disagreement as to whether both terms are correct. Some maintain that "aerobatic" is correct, while "acrobatic" is incorrect. Others maintain that both terms are correct.

"Aerobatic" refers to flight while "acrobatic" refers to the human body so "acrobatic" is incorrect.

"Aerobatics" comes from "Aeronautical acrobatics" so it is correct.


They're called SPAAG's -- Self Propelled Anti-Aircraft Guns.

Older systems tended to fire 23 mm shells.

Newer systems tend to fire 30 mm shells augmented by short range missiles.

They are equipped with radars and high-speed elevation and traverse motors for the turreted guns, so they can react quickly to fast a/c flying low ahead.

They're also useful against attack helicopters, which also hug the ground (see below).

These are short range weapon systems, typically only effective under 10,000 ft, the guns at much less than that.

They're still useful even today.

Medium and long-range SAM's have forced a/c to fly low, below their search and fire control radars, but within range of the guns.

This was standard NATO doctrine during the late Cold War--- low level penetration ---and

gave rise to the F-111 (for example), which was designed to fly fast and low, hugging the bumpy terrain of Central Europe.

This would have worked very well had the Soviets not fielded SPAAG's (basically modern AAA) and developed their own MANPADS (shoulder-fired SAM's).

Soviet AWACS and look-down shoot-down radar also contributed to the decline of this tactic.

These systems denied the use of low-level airspace so effectively that during Desert Storm, the Coalition air forces basically gave up low-level operations within the first week and switched to bombing from medium altitude exclusively (above the reach of AAA and MANPADS).

Not even the A-10 with its titanium armor could long survive in that environment.

Afterward, they did occasionally venture below 10,000 ft, but typically with special permission and enthusiastic support.

Even after the first week, when Iraqi air defenses were ineffective, few a/c still flew below 10,000 ft because the AAA and MANPADS were too numerous to be eliminated entirely.

NATO air forces are getting around this problem by buying stealth fighters, namely the F-35A, which can hide from SAM radars, allowing it to fly at medium/high altitudes, far above MANPADS and AAA.

But that's for another question/answer.

Here's an older Shilka (Vitaly V. Kuzmin -

http://vitalykuzmin.net/?q=node/306 ):

A later Tunguska (Leonid Dzhepko / Л.П. Джепко): And a modern Pantsir (Vitaly V. Kuzmin - vitalykuzmin.net): (All images taken from their respective wikipedia pages.)

Can a fighter jet traveling at fast speed be brought down by a weapon like an M134 Minigun? or any machine gun?

There are machines guns designed to bring down cruise missiles and jet fighters

but they look like this:

see:

The Phalanx CIWS close-in weapon system for defense against anti-ship missiles.

Phil Handley shot down a MIG19 while his F4 was going supersonic (around Mach 1.2), after both the AIM7 Sparrow and AIM4 Falcon missiles had failed to launch correctly.

Admittedly, this was a one time event, hasn't been repeated since then, but not only can a fast moving aircraft be brought down with a gun, it can be brought down by a gun fired from another fast moving aircraft.

During the Falklands War the British naval ships came under close attack by Argentine Mirage III jets.

The ships' crews would fire any weapons they could into the air to create a curtain of fire that the attacking jets had to fly through.

The attackers typically flew lower than fifty feet to avoid radar, so they were definitely in range.

In fact, they were so low on the flight across the South Atlantic that their visibility was hampered by spray flying up off the waves.

Reputedly, at least one aircraft was brought down this way, but I haven't yet found confirmation.

Nevertheless, it's perfectly possible that with enough lead or a lucky shot one could hit some vital component (like the pilot) and garner a kill.

Records suggest that jet fighters are not brought down by hand-aimed bullet-firing weapons.

7.62 mm machine guns are not usually considered adequate for air defence, but are used when nothing better is available.

During the Korean war (1950-53)

the .50/12.7

mm projectiles fired from the M3 machine guns of the F86 Sabre proved less effective against the MiG 15 than was desirable, frequently deflecting off without causing damage at shallow impact angles.

Question: Can a fighter jet travelling at fast speed be brought down by a weapon like an M134 Minigun or any machine gun?

Can a fighter jet be hit by guns?

Phil Handley  shot down a MIG19 while his F4 was going supersonic (around Mach 1.2), after both the AIM7 Sparrow and AIM4 Falcon missiles had failed to launch correctly.

There is a known instance of a fighter jet being shot down by another aircraft.


I'm going to interpret safely as meaning successfully.

Ejections mean safety has gone out the window - literally.

There was a case in the Vietnam War where a pilot continued to fly his heavily damaged F-4 after his RIO (back seat radar operator) ejected.

He managed to keep it together long enough to get back over friendly territory before ejecting himself.

Note, this was an interview I saw some years ago, I haven't been able to find a link to post.

In this case the airplane had been hit badly enough that landing was not going to happen, however if the RIO had ejected accidentally or the airplane less damaged then a safe landing would have been possible.

So yes, flying has been done and landing is entirely possible after someone has ejected.

The first test with ejection seats were performed in 1942 in Sweden with a Saab 17 and in Germany in 1941 with a Junkers 87 and in 1943 with a Heinkel 219 and Heinkel's pneumatic seat.

Of course, then it was not the pilot who ejected but his back seater, but the aircraft did not need much modification for the tests.

In each case, the pilot performed an uneventful landing after the test flight.

Saab 17 (above, source ) and Heinkel 219 (below, source ) during ejection seat trials.

To enable someone to fly the aircraft home after an ejection requires two conditions: The second seat must be equipped with flight controls

The ejection sequencing is switched off, so the seats can be activated independently.

Normally, triggering the sequence from either seat will eject all occupants.

It is exceedingly rare that both conditions are true in a modern combat aircraft.

There have been a few cases where a crew member flew an aircraft to a successful landing after the pilot bailed out, but I know only a single case where the bail-out was done by ejection seat.

It was a Boeing B-47 , and the YouTube link is to a re-enactment of this B-47 flight in which one observer, who was also a trained pilot, took over after the crew had bailed out due to a fire in the electrical installation.

Read the last of the stories from this page for one accident in which everyone but the pilot ejected from an S-3 with a stuck nose wheel, and the pilot later performed a safe landing.

I guess you are concerned about the damage done by an ejection.

The firing of the rockets happens in the rear part of the now very well ventilated cockpit and is a very brief event, so the flight controls and instrumentation should be in working order after an ejection.

However, after the event nobody will be there to take over, and there is no way another crew member will be able to take over unless he/

she has his/her own set of controls.

There have been cases of inadvertent ejection seat activations by mechanics on the ground.

When this happens, a new ejection seat is needed, the shear pins and in most cases the canopy need replacement.

After that, the cockpit area needs to be checked and cleared.

But the airplane will return to service.

Fun fact:

The XB-70 had ejection capsules to make ejection at supersonic speed possible and to protect the pilots in case of pressure loss.

Life support systems and a minimum set of flight controls were duplicated inside the capsule, and the pilot could continue to fly the aircraft down to a safer altitude after initiating the encapsulation sequence.

Only then he would trigger the ejection.

The fighter can remain airworthy (in the technical sense not in the regulatory sense) after ejecting.

For example the cornfield bomber made a belly landing onto a field after the pilot ejected.

Martin Baker uses (or used, it may have been retired)

a modified Gloster Meteor to test ejection seats.

The aircraft is piloted, with the seat being in a separate area behind the cockpit.

This aircraft is definitely reusable, it's been used to test ejection systems many times.

So yes, it is possible to design an aircraft in such a way that it can be flown after an ejection of (one of) its ejection seat.

Of course in case of operational ejections these are usually done after the aircraft has sustained enough damage that it can't be flown anyway, so having it flyable after ejection isn't a high priority.

And without the crew on board it becomes even less of a priority, as the crew are the ones flying it in the first place.

There was a case when Soviet MiG-23 was flying for more than 500 miles after ejection of pilot.

Question: What kind of damage does the ejection process do to the inside of a cockpit or to the aircraft in general?   If ejection were accidentally triggered on the ground (i.e. the ejection wouldn't be followed by a hull damaging/destroying crash), would the damage be minimal enough that it could be flown again by simply installing a new seat and canopy, or would it have to go through a major inspection to ensure no additional damage was done to instruments, wiring, etc?

Can an aircraft be controlled after an ejection?

The fighter can remain airworthy (in the technical sense not in the regulatory sense) after ejecting. The flight controls and instrumentation should be working after an ejection and there have been recorded incidents of planes continuing to fly after an ejection, notably in the Vietnam War and a Soviet MiG-23.

The aircraft should still be operational after an ejection, and there are known examples of planes continuing to fly after an ejection.

There are known examples of planes continuing to fly after an ejection.

The aircraft should still be operational after an ejection.


A big part of the difference in range between small and large aircraft is simply mathematical.

When you make a 3D object larger, area increases with the square of length while volume increases with the cube.

The A320 has a wingspan of 35.8m, carries 150 (2-class), and carries 24,210L of fuel (standard).

The A380 has a wingspan of 79.75m, about twice the dimensions of the A320.

However, the passenger capacity increases by a factor of 4 to 644 (2-class), and the fuel capacity increases by over a factor of 10 to 320,000L. There is simply more room for fuel in a larger aircraft.

Smaller aircraft may have options to carry additional fuel talks to increase range.

Note that this trend also applies to business jets despite their market having less of a correlation between range and passenger demand.

In addition to the geometrical constraints, airlines have other reasons for not operating large planes on short routes , or vice versa, more often.

Using small planes allows for more frequent service and more flexibility even if there is enough demand to use a smaller number of larger aircraft.

There are five points that need to be addressed on the graph of range vs capacity, not just two.

Short and thin.

These routes are flown by small aircraft such as puddlejumpers and regional jets as well as smaller mainline aircraft, and represent the spokes in the classical hub-and-spoke model (Savannah-Atlanta or Bordeaux-Paris for instance).

Service frequencies are low to modest, and competition is generally fairly limited, with one or a few carriers on the route.

Short and fat.

These routes mainly exist in areas where there are large cities close together, but land/sea connectivity has a tough time competing due to geographical or political issues.

Examples of this include Tokyo-Osaka and Taiwan-Hong Kong.

Oftentimes, service frequencies are high, competition is fierce, and both narrowbody and densely configured widebody (2-class seating at best)

aircraft can be found.

Long and fat.

These are your classical, long-haul hub-to-hub routes such as London-New York or Los Angeles-Sydney.

Most of these flights are on traditional 3-class or 4-class configured widebody aircraft, and see relatively infrequent service compared to shorter routes.

Long and thin.

These routes are introduced to relieve congestion from major hubs, usually in international markets.

An example would be Newark-Glasgow, bypassing the otherwise-obligatory plane change at Heathrow or Amsterdam.

Other examples of this pattern include US domestic long-hauls.

In the middle.

Most short-to-intermediate haul mainline flying is this way -- these may be busy hub-to-spoke connections, or inter-hub flights that aren't fat enough or long enough to sustain the use of larger aircraft.

LCC networks (Southwest, JetBlue, Ryanair, Easyjet) center around these types of routes because they work well for a homogenous fleet (vs. hub and spoke networks, which require smaller planes for the spokes and bigger planes for hub-to-hub).

Basically the airlines need keep their planes always flying, parking them idle on the airport just costs money.

Parking a big plane and waiting a complete day until it gets full with passengers is expensive, flying a small plane a long time while passengers already waiting for the next flight is lost money.

In the past big planes were build for short and medium-routes, like the B747-100SR/300-SR or the A300 (first time

two aisles one

a twin-engine?).

The 747-SR was used a lot inside Japan , while the A300 founds it first customers inside USA.

But the airlines don't buy them anymore.

Consider that on short routes you are often connecting smaller airports with fewer passengers per trip, therefore a smaller plane is more efficient.

On the other side, most jet-engines become more efficient when they are bigger, furthermore long boarding times are not a problem on long distance flights.

Also, one, two or three flights during a day on long routes are okay for passengers on long routes (selecting a round about departure/arrival), while on short routes you may need a flight every hour (selecting exact departure/arrival).

Notable exceptions are current B737-700ER and A319LR, both can fly around 10.000 km.

I don't know the sales figures, but I think only customers with special needs buy them.

There are two design reasons for this: Airline routes In the hub-and-spoke system most large airlines use, larger volumes of passengers are concentrated into a few airport hubs then moved greater distances between hubs.

In that system, there is little need for long distance/small passenger aircraft.

Fuel Capacity

A larger plane can carry more fuel and thus go farther.

Yes, you can get a 737 configured for business that can go as far as an early 747 but, when loaded like that, it cannot carry very many people.

A BBJ 737 with full fuel can only carry about 2500 lbs—about 15 passengers with no bags, no food, no nothing.

In general as an aircraft gets bigger, with more passengers, the bigger the wing has to be to carry all of that extra load.

As the wing gets longer, the root has to increase in thickness quite a bit due to the increased bending moment (also due to the increased load going into the wing).

As the wingspan gets longer, the wing chord usually increases at the root as well (on commercial aircraft).

Finally, since the wing root has has gotten thicker and longer, the center wing under the fuselage has also gotten taller and longer.

Considering the vast majority of fuel is stored in the wings and center wing on commercial aircraft (on many that is the only location of storage), and nearly all of the wing between the spars is dedicated to fuel storage, a higher capacity aircraft just has far more fuel storage volume available.

Of course you could put a huge wing on a small aircraft to give it a lot of range, but I think the other answers have done a good job of explaining why that isn't done.

Question: Why we rarely see an A320 (or equivalent aircraft) on a long route with all premium business seats or an A380 (or equivalent aircraft) with high density seating and on a short route?  On top of that, it is a much easier task to design a long range light aircraft and a short range heavy/high capacity aircraft, so why have no airliners (as far as I know) ever been designed with these characteristics in mind?

Why there is such a strong correlation between the range of an airliner and its passenger capacity?

Using small planes allows for more frequent service and more flexibility even if there is enough demand to use a smaller number of larger aircraft. In other words, 2 or 3 flights a day on longhaul routes is OK but shorter routes need more frequent flight. Moreover, long boarding times are not an issue for long distance flights but would be on short flights. Planes make money in the air not on the ground so keeping a big plane on the ground until it is full is losing money. Finally, large planes can carry more fuel and thus go further.

The main reason this happens is for efficiency and flexibility. It helps to use small planes to have shorter boarding times and more frequent flights for short trips that usually have less passengers, while for longer flights it helps to concentrate passengers in a bigger plane, since longer boarding times and less frequent flights are to be expected in these types of trips. What is more, the airlines do not profit from keeping their planes idle so they schedule their flights accordingly. Another factor is that the bigger a jet-engine is, the more efficient it is and bigger planes have more fuel capacity, thus they can cover longer distances.

The airlines do not profit from keeping their planes idle so they schedule their flights accordingly.

The bigger a jet-engine is, the more efficient it is. Also, bigger planes have more fuel capacity, thus they can cover longer distances.