I'm looking forward to calm summer days 'buzzing' the neighbors dog, dropping markers on targets, and imagining what it would be like to fly a real plane. This year though... I've decided to experiment with telemetry.
The Mini Swift from Hobby King. is an incredible deal. It comes with a 'crash kit' which includes enough extra bits to make a complete second plane. Trouble is... there isn't a lot of room inside. So... if you want to add telemetry in one of these small planes, you're going to have to be creative.
I've come up with a telemetry module that you can squeeze into the canopy. A rubber band around it should keep things together during rough landings.
I've tried this once before and a pad antenna is just too much... the added weight and rigid cable make it feel like I'm flying with a ham sandwich stuffed into the body of the plane. So... I'm going to try a tiny antenna by Sarantel instead ( hasn't come yet ). The one I have in there right now is helping me figure out where the CG is.
The brains behind the beauty... is the Venus GPS from SparkFun. The stock module comes configured at 9600 kbps. In order to get it talking with the easyRadio... you'll need to get the configuration utility and bump it up to 19200.
How smooth is your loop-the-loop you say? With your telemetry data in-hand, you can plot your flight patterns and see. Remember the movie Cool Hand Luke? Yeah. Just like that.
To assemble the carrier for your telemetry module, you'll need:
- soldering iron
- a section of female headers
- a battery connector
- kynar wire ( or thin wire for the 'circuit' )
- liquid tape ( to make sure nothing grounds out )
- a little bit of electrical tape
- small section of double sided tape
- a GPS that has a serial out - smaller is better
- two easyRadio modules - 433 or 900 mhz model will do nicely
- a length of 24 gauge copper wire ( antenna for the radio )
...and here's the muscle: easyRadio. Capturing a stream of GPS data during flight has never been so easy! You can get the data stream on your laptop via an FT232RL from SparkFun or similar ( more detail on that coming soon ).
I typically get about 30 minutes out of the little 110 mAh 3.7v lipo. I've tried the 80 mAh as well... which lasts for about 20 minutes. I'll follow-up this post with an instructable on how to assemble the carrier.
The hardest part... will be waiting for a day to fly - summer can't come soon enough!