Accurate altitude measurements?

[jpanhalt]

@dknguyen
If those advantages exist, why is there not a single autopilot or flight instrument (except the pilot) for full-size aircraft that utilized horizon sensing?

I disagree about the "absolute" attitude reference. That is certainly not the case above, but near clouds, nor when there is lots of haze. It is also not the case at altitudes where ground irregularities (e.g., hills and mountains) interfere. In other words, it may apply at relatively high altitudes --altitudes at which models are not supposed to fly. And, it is useful for some aspects of model autopilots. I disagree simply that it is better than or even equivalent to a gyro.

John

 

[dknguyen]

@dknguyen
If those advantages exist, why is there not a single autopilot or flight instrument (except the pilot) for full-size aircraft that utilized horizon sensing?

I disagree about the "absolute" attitude reference. That is certainly not the case above, but near clouds, nor when there is lots of haze. It is also not the case at altitudes where ground irregularities (e.g., hills and mountains) interfere. In other words, it may apply at relatively high altitudes --altitudes at which models are not supposed to fly. And, it is useful for some aspects of model autopilots. I disagree simply that it is better than or even equivalent to a gyro.

John

Full size aircraft don't use them because, like you said, they can fly above clouds and may have the need to fly in non-mild conditions like storms. But we're not talking about full-size aircraft. We're talking about UAVs that tend to fly in mild weather at low altitudes.

I didn't say they were "simply better" and but they certainly are more feasible. Most, if not all inertial systems cost more than any aircraft available to a regular consumer. And for most RC work around uneven terrain, I would think that something that believes the ground is a little more sloped than it really is it a lot better than something that would eventually think right-side up is upside down. Sure there are ways to compensate for that, but it all costs extra, and a cheap uncalibrated gyro system already costs much more than the thermopiles to begin with. Thermopiles simply have less risk and cost than a gyro system. Yes there are limitations but feasability is often more important and something that is feasible for Boeing might not be feasible for us. The cost factor also helps since UAVs are often expendable...unlike a passenger jet, I would hope.