I had always thought you were supposed to high speed taxi test. Never thought it was an option. And we can guess forever if it is smart or not.
Personally, I am a fan. A friend bought a Pulsar. Got it all back together eventually and asked me to accompany him to the airport to check her out. We got there and he did multiple taxi tests. I thought they were too low speed. The tail only got off the ground once or twice. So I thought he was just checking engine temps etc. Then after about 20 minutes, he just takes off. Not a hop but a takeoff. Enters the pattern and the whole time I am yelling at the air, "Why are you so damn low"? Turns out the engine crapped out and he tried to get back to the airport. Kind of made it. Crashed right beside the runway. Would have made it but he hit the fence first. I was running down the runway to him. Airport manager saw me running by and he had the sense to grab a fire extinguisher before driving out to the crash. I got there, pulled Jerry from beside the plane about 20 feet.. he had actually managed to crawl out. Plane was on fire and despite the extinguisher it burned completely up. Jerry had a broken hip and some gashes but is still alive today Still in hip rehab. My feeling is that he could have done some runway "hops" to get a feel for it. But not take off. Maybe the engine would have died during a hop. Maybe not, but it's best to have the you know what hit the fan while you are reasonably safe if you can. For me, I am getting closer, but we do have a professional at our airport and he will do the first flight. If anything goes wrong he has a better shot of handling it than I would. I will do taxi testing and maybe some hops, but not a flight off the airport. Not the first one. As Larry always say, your mileage may differ. Ray_pilot New Orleans On Mon, Jul 29, 2024 at 6:01 PM victor taylor via KRnet < krnet@list.krnet.org> wrote: > I test fly experimental aircraft professionally. There are arguments both > ways on whether or not to do high speed taxi test. > I had an incident about two months ago where the client said the airplane > was ready to go. It looked ready but my policy is that I don’t test fly > without high speed taxi test. Everything went well until I pulled the > engines back from a full power run down the runway and both engines quit > simultaneously. I was told that I probably pulled them back too fast. So on > the next pass down the runway an engineer was sitting in the right seat and > we lifted off and I eased the power back very slowly only to find that both > engines shut down again. Obviously this was a problem that I was glad had > happened while over the runway rather than away from the airport. > Turns out it was a manual to electronic handoff of the throttles and when > power was reduced while at speed the props would windmill causing the > electronics to sense a problem and thus shut both engines down. > The engineers looked at it then redesigned the electronics which solved > the problem. > Bobby Ibrahim was a close friend of mine that died a year ago on a test > flight. Had he done a high speed taxi first he would have found the > airplane to be unsafe to fly and would not have gotten killed. > > Pilots do things differently but for me I’m sticking with what has kept me > safe for all these years. I won’t fly a new plane until I’ve done runway > hops. > > Victor Taylor > > On Jul 29, 2024, at 17:52, Samuel Ajayi via KRnet <krnet@list.krnet.org> > wrote: > > > I disagree with this notion. There is nothing wrong with "high speed taxi > test". There is no certified production aircraft that has not gotten > through that testing phase. High speed taxi will accomplish several items > that must be determined as part of the certification process. For example, > how maneuverable is the aircraft on landing or takeoff roll and what is the > braking distance from the time you identify an emergency and apply brakes > to the time the aircraft come to a stop. Will the temperatures exceed > sub-component rating? Based on your weight and speed, you may not be able > to stop the aircraft in sufficient time and may have to commit to take off. > These are just a few things you need to understand/consider on a one-off > type design. > > What is critical to understand is brake temperature and what cool down > period should be observed between each attempt. If component manufacturer > does not provide such information, then is it left to the aircraft > manufacturer/builder to determine what those should be. There are many > things to determine at the onset to figure out which component drives your > temperature consideration. > > Unfortunately, light GA airplanes don't typically have a probe at the > wheel to give instantaneous temperature reading. A small infrared > temperature from Amazon should do the trick. Stop and get out of the > aircraft or have someone point it at the inboard portion of the wheel or > caliper. Because most builders don't install wheel pants until much later, > this issue may not manifest if at all. > > Just a thought. > > ------------------------------ > *From:* KRnet <krnet-boun...@list.krnet.org> on behalf of MS < > propbala...@att.net> > *Sent:* Monday, July 29, 2024 1:38 PM > *To:* Larry Flesner via KRnet <krnet@list.krnet.org> > *Subject:* Re: KRnet> KR Wheel Fire Write Up > > The story provides a great illustration of the good sense of not doing > "high speed taxi texts" and the using of brakes for anything except holding > and the occasional short runway. > > Mike Stirewalt > KSEE > > -- > KRnet mailing list > KRnet@list.krnet.org > https://list.krnet.org/mailman/listinfo/krnet > > -- > KRnet mailing list > KRnet@list.krnet.org > https://list.krnet.org/mailman/listinfo/krnet >
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