Actually, Derek, Matt told me that he did have a prop strike that broke that prop, but didn't realize it until he flew the next flight. The cracked prop blade apparently bent back dramatically, but did not come off!
I will not use these props, although I flew Matt's plane after the Nays with one of them (With Matt's admonishment to not do a long takeoff roll...) and found it yielded tremendous line tension; more than I felt necessary. I would support some kind of fact finding on these props as to the safe use in our event. Banning them outright at this point would be a bit rash I think.
Based on the few I have seen, they are pretty light and didn't look like they would spear anyone more than a few feet away. If that turns out to be true, then there's no reason to ban them. If it just destroys the airplane, then it's up to the pilot to determine risk/reward, I figure. Kenny may just had the misfortune to find out why they call it the "bleeding edge".
I have seen a bunch of APC electric prop strikes and no completely separations, so that seems OK to first approximation.
I don't know how you determine which are "quadcopter props" and which are "safe". Where do you draw the line on how tough the hubs are, and how would you test it? If someone starts making custom electric props, how you know which ones are OK and which ones are not, without extensive testing? If someone is making them in their garage, are they all the same, or does it depend on how hit it is the day he made it?
I deal with failure analysis on a regular basis, in aerospace. Usually, having exceptionally tight process controls and very careful tracking, you can trace failures to specific issues. That's why you end up with $900 toilet seats. But you still have random failures that you never really explain. None of that exists in this case, who knows what happens in the factory, and who knows what happens in someone's basement? Maybe the line voltage was 122 volts instead of 115 volts that day, and it made the "incandescent light bulb autoclave" 15 degrees hotter than normal? Stuff like that happens all the time, even in professional aerospace shops.
Howard is probably right, just plain maneuvering doesn't seem sufficient. Hitting it on the ground, or running it through the grass a few times, is clearly another story.
Brett
Topic: Team USA and the World Champs (Read 54575 times)
