11/6 GPS navigation probably worked!!

I\'m psyched!

I\'ve been analyzing the logged data from my last flight on 11/6, and it looks like the GPS-steered parachute navigation toward the pad was probably REAL (not an accident, as I\'d feared).

Details are here: nerdfever.com/wp-content/uploads/2010/01/Flight-Test-Notes3.pdf

I\'m not 100% sure, but it looks good.

I\'ve vastly shortened the parachute lines and have a new packing method which I hope will prevent the lines from tangling. I\'m going to try to improve the steering algorithm (to cope with lots of unexpected noise in the GPS fixes) and try again on Saturday (winds permitting).

--Dave

Very cool.

It sure looked like it was heading back towards the pad.

Great news!
I\'ve followed this project for? I guess a couple of years now.

Nice to see good results from something so complex.

.

You launch your rocket with the wind blowing from west to east. The rocket goes straight up but on the way down it gets carried to the east by the wind. How do you get back to the pad?

The parachute, just like a glider, has some forward airspeed. (About 12 MPH the way it\'s setup now.)

As long as the wind speed is less than that, the rocket can make progress even upwind. It knows how to compensate steering for the wind (in theory, anyway).

Suppose the wind is 8 MPH, and the pad is straight upwind from the rocket. The rocket faces into the wind and flies at 12 MPH airspeed, so it makes 12-8 = 4 MPH toward the pad.

If the wind is faster than the airspeed, then it doesn\'t work (and as a matter of fact, the software will get confused and won\'t even figure out how to steer upwind - but I have ideas on how to fix that...)