Taxi Testing (was Aeromomentum engines)

[racaldwell]

Yes, I agree with minimum ground engine running and I see no benefit from high speed taxi tests.

But just last month, my first taxi test showed me that the differential brake pedals I bought from a group sale here on Sonexbuilders.net was a potential disaster. I am so glad I found out how weak they were and bent & cracked right on the taxiway in front of my hangar. After reinforcing with chromomoly channel, they are now functional. I tried to give a heads up on those brake pedals but nobody said they had the same experience. Guess they have not taxi tested yet. If they go straight to first flight, then the first landing with braking could very well end badly.

Rick Caldwell
Xenos 0057 N137RC

[Scott Todd]

Thank you Rick :) Its important that readers understand he MODIFIED the original airplane design by adding differential brakes. There is nothing wrong with that but now he has become a Test Engineer and more Test Pilot skills are required. Certainly low speed taxi testing was warranted. I did mention you could taxi to the fuel pump didn't I ;)

Lets say Rick didn't realize the brakes were defective and taxied to the runway with minimal braking, performed his run-up, and successfully performed his first flight. On rollout, he tried his brakes and they failed. Hmmm...Well he was testing on a long runway, was prepared for such an incident (he is a Test Pilot after all) and simply rolled to a stop. Maybe his idle was too high and he decided he needed to kill the engine to stop. Well his safety crew was right there to help him push it off the runway. They can go enjoy their celebratory cold drink, or warm if its winter, and talk about that exciting flight.

It says its an EXPERIMENT in big letters in plain view. You are the original Manufacturer and are now a Test Pilot. You can certainly do what you want but aren't you glad you did all that preparation and got that extra training for the occasion? :)

[Sonerai13]

One of the things that gets pilots in trouble when doing "high speed" taxi testing is that they don't realize how little power it takes to keep an airplane moving once you get it moving. Many taxi accidents are caused by airplanes becoming airborne when the pilot is not ready. The usual reaction is the force the airplane back on the ground, which leads almost always leads to a bent airplane if not worse.

Once you get the airplane moving at a speed that most would consider "high speed taxi", you can (need to) pull the power back nearly to idle to keep the plane from accelerating to liftoff speed. Failure to do so invites disaster. For this reason, I almost always discourage high speed taxi testing unless the test pilot is very experienced in flight test operations. You don't learn enough from high-speed taxi testing to take the risk.