The rocket car was build from three RTF model rockets, a cardboard roll, 3 mm stainless steel wire, four 56 mm dia. TAMIYA racing wheels, plastic tubes, a lot of epoxy, aluminum foil and Epoxy Resin Putty.
The rocket car weights around 400 g and will be propelled by two C6 blackpowder model rocket engines. I plan to measure the burnout velocity. The wheel encoder (from an damaged printer) is mounted on one of the front wheels and contains two Hall sensors. The wheel encoder has a resolution of 30°.
The ignition of the rocket motors is remote controlled. After the burnout time is reached, a Picaxe 08M counts the wheel encoder impulses in a defined time intervall and display the value via two CMOS 4026 on a 2-digit-7 segment display. It is then easy to calculate the burnout velocity. I will compare the measured burnout velocity with the calculated burnout velocity by the rocket car equation I have derived.
2010.6.16: New video is up! Have fun and more soon!
https://www.youtube.com/watch?v=fmhvzMhj-Kk
another interesting robot
another interesting robot from you, what speeds are you expecting?
Here’s one i made a while ago:
http://www.youtube.com/watch?v=4nG_i-G2BPw
Unfortunately the chassis melted after the barrel roll 
Rocket was KNO3 + sugar, 60/40.
how do you measure distance
how do you measure distance with precision? :-? at this speed sometimes the wheel shouldn’t touch the ground and even spin faster or lower so the wheel encoder isn’t the best idea
I have derived the rocket
I have derived the rocket car equation (without air drag) a while ago, see here. Air drag neglected and an assumed rolling resistance coefficient of 0.72 I am expecting a burn-out velocity of around 54 m/s (≈194 km/h) if the rocket car is propelled by three C6 motors.
I don’t care about one meter
I don’t care about one meter more or less. The short time the wheel maybe not touch the ground, is negligible as it still spin at this short time nearly with the same resolutions. The wheel encoder has a resolution of 12 30° btw.
yeah…listen to the engines
yeah…listen to the engines moaning…here I am, on the road again…but you just want to explode…
As I shoot this video, I had this song from Metallica in my head…
Guys in this whole site i
Guys in this whole site i feel like i am in the emission Prototype This and this rocket ROCKS!
RE
Nice job on the rocket car.
I built one of these like 20 years ago. I still have it here somewhere. I got mine to reliably launch straight by doing 2 things different than yours:
1. use puffy rear wheels to better absorb ground deviations
2. lower the front via small wheel(s), so during launch it raises to level itself off (does a wheelie!!!) and only the rear wheels touch the ground.
After setting mine up this way it would go 600ft straight every time, and it was much faster while doing so.
Once I find mine I’ll post a picture of it.
Thanks. Would be cool if you
Thanks. Would be cool if you could find your rocket car and post a picture here.
RE: Pictures
Wow that was some digging, but I found my old rocket car.
Here’s some pictures:
~ Yeah that is a Teenage Mutant Ninja Turtle sticker on the rocket car :-)
cost
hoew much wiil this robocar cost
Around $30 as I have
Around $30 as I have mentioned above.
another interesting robot
