Question: In Star Trek Beyond, they fix up the old Federation ship, USS Franklin. It wasn't made to fly in atmosphere, so in order to take off they need to propel it off a cliff and reach terminal velocity before the impulse engines can fire. (From what I can recall from a single viewing - if any of those assumptions are wrong please correct.) 

What I don't understand is *how* does terminal velocity allow impulse engines to just "start working"?

Answer: 
The quote from the film is 

> 
> **Kirk:** *Scotty, can you get this thing started?*
> 
> 
> **Scott:** *Started yes, Sir. Flying, that's a different thing. These old vessels, they were built in space. They were never supposed to
>  take off from atmosphere.*
> 
> 
> 

then

> 
> **Chekov:** *We have to achieve terminal velocity **in order for the stabilizers to provide lift.***
> 
> 
> 

Quite why this is the case isn't explained other than it being [treknobabble](https://memory-alpha.fandom.com/wiki/Technobabble) to explain why they need to push the ship off of the cliff.

---

Stabilizers are, at least in the Abramsverse, an integral part of starship atmospheric flight

> 
> “Mr. Sulu,” Spock exclaimed, “divert all remaining power to stabilizers!”
>  “Doing what I can, sir,” the helmsman replied as he desperately fought to comply. “Doing what I can.”  
> 
>  Spock tried his best to see that the Enterprise’s vanishing energy resources were parceled out meticulously among the ship’s most critical active systems. While life support drew the most attention, he and Sulu attempted to steady the starship’s wildly skewing and rapidly failing artificial gravity. If he couldn’t stabilize it any better, there was a good chance a large percentage of the ship’s crew would never be able to make it to their assigned evacuation stations. Yet if he shunted power from life support to the precessers, there was a chance atmospheric pressure would fall too low and kill everyone on board.
> 
> 
> [Star Trek Into Darkness - Official Novelisation](http://kn)
> 
> 
>
They specifically get the inspiration from the idea of the jumpstart. Then they basically "push started" the starship. So I'm assuming the older starships have a manual transmission, and they popped the clutch after getting up to speed. On a car, the wheels transmit the motion to the engine and engaging the engine suddenly can get the engine running without a battery. So, I guess there's something that rotates or moves on the basis of the air (or solar wind?) traveling on the outside of the hull, and engaging the engines suddenly allowed them to start without the power cells working.

But honestly, this part of the movie bothers me more than anything else they've done. It just makes no sense at all!