[AirMcNair]

I went and asked one of the Tec guys a question on a system to save our airplanes and people. This was his responce.....

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My question
So I was talking to a buddy last night and thought there must be some way to keep these airplanes from going crazy and flying into a group of people. With a lot of us having 3000.00$ plus giant scale airplans. What if we had some type of system that is GPS guided. Somthing that the servos have to connect to after comming from the RX. This system could have a 5 Axis lazer system just like those Auto Pilot boxes, Connect to a GPS system and gyro with a wire comming from the RX so in the case of PCM Lockout or FM signal loss the System could take over and do what ever is programed. I know it would not be cheep but does anybody think its possible????
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First off, consider that if your protection system goes crazy, that could lead to a crash in and of itself, so you have to be really careful with this stuff. The more complicated you make your onboard systems, the more points of failure you have, and you can't always make every system onboard triple redundant and you can't always eliminate every single point of failure. Also, you can't necessarily control things like engine failure, bird strikes, mid-airs, an any number of other unforseen circumstances. Even with all our care and technology, full scale aircraft still unfortunately go down once in a while.

I can imagine that a simple AP that activates when signal is lost, might be good enough for many situations, but what fun is an off the shelf solution. :-)

I've been playing around with ideas in the back of my head for ways to take a programmable autopilot system (like the crossbow unav) and use it to build a safety/protection system.

For instance, you could layout 3 zones in your R/C airspace, green, yellow, and red.

The innermost zone is green and is where you would go crazy and do anything. That would be bordered (encased) by a yellow zone where you are starting to get into dangerous territory ... maybe too high, a bit too low, too close to the trees, too close to spectators, etc. Finally you would have a red zone everywhere else. This would be the do-not-fly zone, over spectators, near or below ground, etc.

You could setup a system that passed control inputs through to the servos directly when you are in the green zone so you have full, normal, manual control over everything, just like flying any standard R/C airplane.

When you go into a yellow buffer zone, the onboard system would start to kick in and limit what you can do. Perhaps it would limit your roll angle to +/- 45 degrees, and limit your pitch angle to +/- 20 degres and possibly right you if you are inverted or some other wierd attitude. You would still have some control, but it would be "cooked." Perhaps if you are in a yellow zone and heading towards the red zone, the system would kick in and force a turn or a climb or a dive until you are pointed back away from the red zone, then return semi-manual control until you guide your airplane back into the green zone.

Then in the red zone, the autopilot would take over completely and expedite your return back into green.

If you detect loss of signal from the transmitter the onboard system would immediately take over, stabalize the aircraft and return it to home and perhaps enter a holding pattern until transmitter signal is recovered.

There are issues though ... if your buffer zones are too small and you hit them at 120mph, you might be able to blow through them before the system and the aircraft can adequately respond and recover. If you buffer zones are too big, then your flying is greatly restricted.

The crossbow unav isn't cheap and it has some of it's own single points of failure, so great care would be needed in selling this as a safety system.

But I think their are a lot of possible directions you could take this. You could put a system like this on a trainer and have an aircraft that a student literally could not crash no matter how hard they try.

You could put a system on a higher end plane as a backup/safety/sanity check.

Another variant would be to program a "fly-by-wire" system similar to an airbus where your stick inputs are commanding a roll rate or a pitch rate, but when you center the sticks, the autopilot holds your current pitch or roll angle. You still have "full manual control" but the results are "cooked" and your sticks are no longer directly connected to the control surfaces. I wonder if a scale or jet pilot might find something like this useful. With on board stability built in, you could make an airplane fly much more stable and "scale like." One of the things I dislike about R/C models is how they waggle around so much because the pilot doesn't feel the onboard forces as they give their control inputs. A smart system onboard flight control system could yield a much more stable, "scale flying" aircraft.

Another thing you could roll in with all of this is that the onboard system knows your stick inputs, knows your aircraft location, attitude, speed, and you could possibly integrate a few other sensors for rpm, engine temp, battery voltages, etc. The onboard system could self monitor the aircraft and cross check different variables to make sure they are in allowable range. The system could flag potential problems before you could detect them from the ground ... dimininshing battery performance, out of range engine temps or rpms for your throttle setting, maybe even be able to detect that you are way out of whack in some control surface input for your current speed and direction (control surface or balance problem?) and then the system could take some action to notify you that there is a problem.

But realistically you are probably looking at somewhere in the neighborhood of $3000 to not take a loss on building something like this so your market wouldn't be too big. But there are people that invest this much or more in their equipment and perhaps a few of them would be willing to invest a bit more for a better or safer flying aircraft?

I've got some xbow unav hardware sitting on my desk, I'm just lacking time to fiddle with it much right now. (Dang day job) :-) The xbow hardware would be capable of achieving all or most or maybe even more than this, it's just a matter of finding the time to develop the code to do it. Se habla dinero. :-)
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