I searched here and goggled it. Why aren't there any mechanical pitch controls for airplane propellers but there are on helicopter rotors?
Thanks, I see there are and were mechanical systems out there, that's good. Unfortunately I'm using either direct drive or an in line psru so I can't use the inside-the-shaft actuation. Electric sounds good, I guess if it locked in place during an electrical system failure, would be safe.
I like the idea of using a lever or a hand crank though, and it will need to use a slip ring actuator, a push-pull slip ring should be easy to make. Is there anything like that out there without the inside actuator? now or has been? there must be.
I agree, a sealed bearing unit is the way to go.Some used a fork-and-slip ring affair similar to the shifters in a manual transmission. Best would be a sealed ball bearing device similar to what's used as a swash plate on helicopters.
There was a guy a few years ago that was converting turbine APUs to homebuilt engines, complete with geared PSRU and mechanically-controlled propeller. Can't remember the name of his outfit. Something here, though:Can you think of any names to suggest that I can look into, or are they all home made?
larger diameter favors climb speed, and I favor that to; besides I intend to eventually jack it up to over 500 hp, way over, so a big prop will be fine.8 to 10 feet is pretty big. I bet it will be efficient at just one speed and inefficient at other speeds even if you adjust the pitch.
We already have tip speed issues with direct-drive and PSRU's propellers. With a two-speed setup you will run into it even more. Jim Bede tried a transmission in the first BD-5 but it was worth less than the trouble it raised. You need a low-pitch propeller for low forward speed, so your propeller will have to have a low pitch. If it turns slowly it will need to be large to get the necessary thrust for takeoff. Then as you shift it, its tip speed gets so high that it loses too much HP to drag (and noise) and you don't gain anything.There doesn't seem to be much out there. I've been thinking that since I'm going to be using a psru that it might just be better to make it a two speed unit rather than having a controllable pitch prop. I'm going to check the difference in costs, I think a two speed psru just might favor simplicity ... but heavier? Could be close on weight.
You would require 1.4 or so. That's about the same as the Nemesis NXT or the Lancair 360. Seems indeed hard to achieve for a 500HP airframe...180mph on 63hp while toting around the weight a 500hp engine is a little hard to believe. What kind of wing area and equivalent flat plate area are you using to come up with this?
I guess that 63 was thrust horsepower rather than crankshaft horsepower (big green grin smiley face goes here) little details like that can make a difference sometimes (ROFL smiley face goes here)180mph on 63hp while toting around the weight a 500hp engine is a little hard to believe. What kind of wing area and equivalent flat plate area are you using to come up with this?