One of our club members claims he "read" where a model aircraft flew by a commercial airliner at 12,000 feet. Without carb heat and adjustable mixture could a model aircraft operate at this altitude?
Thanks in advance
Don

I seriously doubt it. I think a gas or glow model even if it kept running as it gained altitude would be so down on power that it would either not be able to climb to that altitude or would have such a shallow climb that it would run out of fuel before reaching that height. Electrics for the most part don't have the duraration to get up there either. Granted this is based on hobby type setups. IMO most of these " close calls " are bogus. An airliner flying at 300 mph passing by a near stationary object the size of an average model airplane or quadcopter the object will be in veiw but just a couple milliseconds. The current rage is to blame the drones for everything so that's what happens.

I posed the same questions to him as well. But Like my Father once told, me believe half of what you see and none of what you hear.
I think it isn't possible.

Impossible? No.

Improbable? Yes.

Rafael

Well a while back some one flew a standard Super Tigre 60 to 27,000 feet breaking Maynard Hills long time record. Maynard used a standard Fox 59.

Read more here http://www.fai.org/download/RECS/2430-3.pdf

As normally equipped for RC use, not possible at all. You'd be blubbering rich way before getting that high. But in an experimental plane purpose built to fly that that altitude, it's plausible. Of course, someone with that kind of expertise wouldn't be so stupid as to fly near the path of an airliner. The story is bunk.

I have my private pilots licence. I found it hard to find and see a full scale aircraft when looking for traffic in the landing pattern. To see a "drone" IMO would be near impossible unless it were DIRECTLY in your flight path at YOUR altitude so it appeared stationary in the wind screen JUST before it entered the cockpit through said windscreen.

Ken

To go back to the OP's original question, I don't see why you couldn't fly a glo, or gas powered model airplane @ 12,000 feet IF and that's IF it were launched (normal take off) from an 11,000 foot up mountain runway. If correctly needled before take off the mixture change at another 1,000 feet up would be no different than wherever altitude you fly from and then going up another 1,000 feet. Yes, the engine output would be less than at a lower altitude but if the model were well powered why not? The guys from Colorado should have a little first hand knowledge on what the limits would be. As we all know the thinner air would reduce the wing's lift and the engine power but heck a lot of the Rocky Mountains are taller than 12,000 feet and people fly RC out there!

Yes, they do fly out there, but they are only flying a maximum of 400 feet above the point that they adjusted the fuel mixture. I KNOW it's 400 feet or less because it's against FAA regulations to fly higher than 400 above ground level and I am confident nobody would want to bend FAA regs.

If high nitro as set really rich yes. Alcohol and nitro will not cool the air as much as gas so carb heat would not be needed. Also the fuel has a wide latitude for mixture especially with high nitro percentages.

That said I doubt anybody with enough knowledge to operate a glow engine would be stupid enough to do this. Most of these people are using electric motors, no knowledge needed.

Carb heat wouldn't be an issue if there is no mositure. Back in the day with a Pratt R 2800 we didn't fly around with carb heat on. Temp isn't an issue if you fly in the summer. Avg temp change of 3.5 deg per 1000 ft. 100 deg day at 12000 it's still 58 deg.
yes it's possible

I may be incorrect but as of today the 400 foot "rule" is only within 5 miles of an airport. I do not believe there is a "law" against over 400 feet only a recommendation.

Ken

If one felt the need to adhere to a 400' maximum altitude rule and wanted to fly @12,000', I guess he would just take off from a runway located @ 11,600'. See how easy that was?

I believe it says you'll fly below 400 ft.....this I will do takeoff, approach, landings. It never says I won't fly above 400 ft.