Re: Control electronics
I've no experience of the accuracy of the accelerometers built into smartphones so I'll take your word for it. I bet that the varios for RC gliders are rather expensive.
It's correct that you can't measure absolute airspeed directly, which is why the instruments include the 'indicated' proviso. The problem with using IAS though, in the context of autopilots/FCS, is that for a constant airspeed (speed through the surrounding air) the IAS will drop quite dramatically as altitude increases and at the very high altitude that LOHAN is expected to reach the IAS will be lucky to hit double digits even whilst under power; I'm pretty certain that once it's gliding its IAS at high altitude will be in single digits, which is not good news for the autopilot/FCS (it could well have to cope with an IAS range that is in the region of, or even exceeds 1:100).
I'm not sure that a barometer will give a more accurate altitude indication than GPS because you can't be sure that, when you calibrate the barometer at ground level on the day of the flight, which will be for the local weather system, those low level weather system conditions will apply at the much higher altitudes that LOHAN will reach; doing so is fine for light aircraft/GA but that's because they don't go very high and stay in the same weather system. One the other hand, whilst a GPS will only be accurate to two or three hundred metres at high altitude I think this could be better than what you'd get from a barometer calibrated on the ground in a relatively low altitude weather system. However, a barometer will be great for air density, which will be useful to the autopilot/FCS.
Biting the hand that feeds IT
