Step 13: Liftoff!

Picture of Liftoff!
Enjoy your command of the skies! Here's another video:

And another one, where it's slightly less than neutrally buoyant:


My motors and servo twitch and move erratically.
You have timing issues between the transmitter and receiver -- one of them takes slightly longer than the other to pulse / measure pulses. Try adjusting the initial delay -- the first thing that happens within the interrupt. You can also try adjusting the time (500 us) that the receiver waits between checking the data line, but I've had little success with that. If you're more competent at writing code than I am -- and you are -- try eliminating overhead from all the clumsy functions I use.

One of the motors won't move.
Check to find a wire loose. Also make sure your H-Bridges are solid. Fair warning -- the motors are great, but the wires they come with are really flimsy. The wire on one of mine snapped off, and I had to pop off the plastic cap and put in my own brushes.

My Arduino isn't blinking -- I don't think it's picking up radio signals.
Find an oscilloscope and make sure your transmitter is pulsing correctly. Jiggle your antenna. Check for bad solder joints on the receiver. Make sure you didn't add a function in the interrupt that clogs it up -- functions don't do well in interrupts. Pray to Philip The God Of Radios Working Properly. Sacrifice your firstborn son.

I sacrificed my firstborn son and now he's dead and my radio still doesn't work. Help?
I had the same problem-- your receiver probably isn't getting power. Check the wiring.

I'm having trouble keeping the reaction cool.
Try a couple rags soaked in ice water -- wrap them around the top half of the the vessel, where it gets the hottest. Make sure you've got in a basin of ice water.

How should I shed weight?
Avoid thick wires at all costs, make them as short as possible. Don't worry too much about the balsa.

My hands feel like they're burning.
You got lye on them, wear gloves.

How should I store my envelope when it's not in use?
If it's just for a day or two, I just leave it attached to the frame and some extra weights so it doesn't go anywhere. For long term storage, I separate the envelope from the frame and just leave it lying up against my ceiling.

What should I do with my salty aluminium oxide water?
I pour it on weeds. It's not hazardous.

I left my reaction unattended because I'm an idiot and now there's explosive steam billowing everywhere and I can't breathe and my envelope exploded and my table is melting and my house is burning down because I'm an idiot.
You're an idiot.