fin tab servos?

Now all is needed is a simple solid state guidance system.

I’ve got one, at least an anti-roll system that I’ve been working on for quite some time. I’ve still ground testing but it looks very robust and reliable. I plan on doing some test flight this spring and summer.

Doug

Sparkfun has a 9DOF board – 3axis accelerometer, 3 axis rate gyros and 3 axis Magnetic (compass). That plus an Arduino or other small micro-controller and servo-controlled fin tabs might make a dandy little project. The only weakness is the accelerometer Z axis is only 6 G’s or so. Survivability is in the 10,000G+ range though so you could fly it even if you didn’t get full accel data. The also have a nice selection of other sensors so adding baro and an high-G Z axis accelerometer might be a nice addition. It would be interesting to see what kind of data stream you could get from the rate gyros and magnetic sensor in terms of roll and absolute roll position.

The interesting part of this to me is that you’ll have to characterize the sensor data (regardless of what type of sensors you use) with multiple flights just logging data to figure out how to interpret the data well before attempting a control algorithm. An interesting project – there is some open source UAV code out there that might be adaptable to this, at least for a deeper understanding of the issues. If someone buys the sensor, I have several Arduino boards and would love to look at at least doing a datalogger.

I have been working with this little beastie with the intention of hooking it to generic data logger, which will make it into a rocket eventually. http://www.sparkfun.com/products/9156

Sadly it has not gotten much attention, got in over my head with clockwork over the winter. I’ll dig out the code, and if I manage to get it into shareable shape, I’ll post for anybody interested. Its straight C with some libs… avr-gcc toolchain. Might have been faster to prototype with Arduino toolchain, i just cant stand that silly editor thingy and haven’t been bothered to pull the guts out so that it will build properly from regular makefile or Ant or something.

+/-16Gs on the sensor is a little scant, but I am not a particular fan rockets which perform instant translation from pad to apogee, so I think it will be ok. IIRC, I picked that sensor after looking at the boost G graph in Adrian’s article on Violent Agreement, max 25G in a minimum diameter 38mm. Though in retrospect, its a very heavy 38mm being a three stager, so I might have choosen poorly. (http://www.rocketryplanet.com/content/view/3087/38/)

I have an Arduino coded to use a 6 DOF breakout and two small HiTec servos for pitch and yaw. Larry Haynes and I are working on a prototype gimbaling system that will utilize either a long-burn Aerotech E6 or G12 R/C motor. Should be ready for testing in a few weeks.

An all-mechanical solution would be cool in a retro way.

My own project that may come up to the front burner sometime this season is a GPS-based, self-returning rocket. I have a cheap RC paraglider canopy on order that should be good for a mid-powered rocket. I would set up the rocket so that it gets deployed out a side hatch and hang horizontally from the chute. A microcontroller would control steering servos based on GPS location to return the rocket to the pad on the way down, or at least as close as the wind will allow.