Water Rocket - Electronic Systems Design
Introduction: Water Rocket - Electronic Systems Design
In this instructable, we are gonna build a Water Rocket with an automatic parachute ejection mechanism, and a data transmission system so we can monitor the rocket's orientation (estimated from accelerometer and gyroscope data) while it's on the air.
A water rocket is a model rocket that uses water and compressed air inside a pressure chamber (usually a PET bottle) as a thrust motor. The operation of the rocket can be explained by <PERSON>'s third law, where the water in the compression chamber is thrown out by the compressed air as it tries to release its pressure releasing the accumulated potential energy, causing a force to be generated in the opposite direction that propels the rocket.
Supplies
Rocket airframe
* 3x PET Bottles 3L size (*It’s important that at least one of the bottles was used to store soda because it has to be able to withstand high pressures)
* 4x Balsa wooden boards 200*25mm
* 8x Screw
* 1x Spray paint
* 1x Rubber band
* 1x Parachute (We used an old umbrella, attaching rope to each tip of the cloth)
* 1x Corrugated plastic board 250*250mm (Also known as Correx or Corriflute)
Electronics
* 4x Zip Ties
* Cardboard
* 1x Perfboard (Also known as solder-able breadboard)
* 1x Accelerometer (We used an MPU6050, it has an accelerometer and gyroscope)
* 2x Arduino board (We used an Arduino nano and an Arduino mega)
* 1x 3.3 V Voltage regulator (We used the LM317 adjustable voltage regulator)
+ For the Voltage regulator circuit using an LM317
o 1x Resistor (390 Ohm)
o 1x Resistor (240 Ohm)
* 1x Servomotor (We used a generic SG90)
* 2x NRF24L01+ module
* 1x Battery to supply power to the electronics board (We used a Power Bank)
* To connect the Power Bank to the electronics board.
+ 1x USB male type A connector
* Female & Male headers
* Tape
* Double-sided tape
* Cables & Wires
* Hot glue
Tools
* Hot glue gun
* Cutter
* Scissors
* Marker
* Soldering iron
* Tweezers
* Measuring tape
* Stapler
* Water Rocket Launcher (We don't explain in this instructable how to make the rocket launcher, but you can check out this amazing article by air command water rockets to build one yourself)
Step 1: Parachute
Measure the radius of the bottle
For this measure the circumference as seen in (1), then apply the equation r = c / (2*pi) (where c is the circumference) to find the radius, in our case the radius was 60 mm
With this information mark 2 circles with the radius of the bottle minus 1 mm (in or case that was 59 mm) on a cardboard and cut them, as shown in (2) and (3).
For each circle, make the lines as shown in (4)
For this, we first make a line that goes through the center of the circle, this line will be called line 1
Measure 40 mm on one end of line 1 and draw a perpendicular line that touches the borders of the circle, this line will be called line 2
Measure 20 mm on the other end of line 1 and draw a point
Now draw a line between the point and each end of line 2
Measure one of the recently drawn lines, this value will be called L
Step 2:
Taking the above measurement (L), draw on the cardboard a rectangle 110 mm high, and (L) x 4 mm wide, mark a vertical line every (L) mm (5)
Cut the large rectangle and cut the line at the middle resulting in 2 rectangles of equal size as shown in (6)
For each of the rectangles, cut the top layer of the cardboard through the marked line so we can fold them
Put hot glue on the lines marked on one of the circles and glue one of the folded rectangles, then glue the other rectangle behind the previous one to reinforce it.
We need holes for the zip tipes, so mark a line approximately 15 mm from each end of the rectangle, and draw 4 rectangles attached to that line approximately 3 mm high by 5 mm wide that are approximately equal distances apart as shown in (9)
Glue the other circle on top
Cut the small rectangles and verify that the zip ties fit through the recently made holes. 120