RE: Accelerometers
Oh, it is very possible to send the telemetry to the ground, the Eagle tree system does that. But, that system is expensive, and while it is cool, I am only really interested in smaller amounts of data. The eagle tree system is very very complicated. I am mainly looking to come up with somethign that I can put together in my free time and assemble with the tools I have available. If I need to I will have pcb's made, but only if I can make them cost effective (ie, less then $10/unit) otherwise it won't be possible for me to do this.
I am not looking to turn this into a business, just something to fiddle with in my spare time and if it works, pass a few on to friends/club members to see if they enjoy having the extra data.
These parts I am looking at are very very low power, on the order of micro amps. They even have power saving modes. This is what really got me thinking about this because if implemented correctly, you won't have to worry about extra weight or power draw. I am shooting for under an oz all up weight, and I think it is very possible when these IC weight as little as a gram. The heaviest part I might have to deal with is the addition of a pcb if needed. If i don't need a pcb, then the other weight factor would be a small watch battery to power it. I have thought about putting a regulator on it and powering it off of the receiver. Hell, it would weight less then a servo and pull less power. I think most guys could deal with that little bit in most airplanes, even in 1/2a planes.
The biggest issue I think I will have to deal with is data storage. I am looking at my chip options to try and find something that can give me 2-5 samples/second and still allow me to store 10min. or so worth of data. If I can only get 5 min., it won't be that bad, but I really don't want to have to add in external storage if I don't have to because that requires me to have more data lines to work with, more code to implement, and overall a more complicated system.
I need to look more into the SD interface accessories (SPI interface I think technically), but there might be other options that I can add for people who might be interested in them.