I have seen this video already a while ago but now, Infinity Hobby has it in their product news. Apparently, some company is making propeller hubs to use heli blades with multirotors.
That allows using of ridiculously big propellers, leading to very efficient setups. Additionally, heli blades are dirt cheap, compared to multirotor blades and with the adjustable pitch (!), there's even no searching for pusher-props any more.
Can't wait until this is actually available!
Comments
It seems that those prop holders allow adjustment of pitch when setting up the vehicle, but once it is flying the pitch remains the same (heli blades have no inherent "pitch" per. se., so it would be a necessity to be able to adjust that one way or another). In concept that is pretty cool, as you could very quickly "change blades" for rpm vs. thrust, while having the benefits of slower spinning motors (less noise), etc.
i did not know there is 5 blade props..anyone have some experience with?maybe this one can excange 2 blade15x5
http://www.hobby-lobby.com/scale_5_blade_11_x_10_variable_pitch_pro...
Nice Norman...did u find any other sizes?
I prefer these propellers with variable step.
I think they are best
http://www.hobby-lobby.com/scale_3_blade_11_x_10_variable_pitch_pro...
with motor like that i would just use this 4 blades
http://www.zingerpropeller.com/4_bladed_propeller.htm
and choose every possible pitch combination you want,replace blades are cheap
http://www.zingerpropeller.com/Xblades.htm
I agree. Blade inertia is a player when transitioning to forward/downward flight right after loss of engine power and then again when transitioning to a hover and setdown. The airflow just builds and maintains the blade inertia until you need to use it for landing.
These small blades don't look like they are spinning very fast and will lose the little inertia they have very fast. Without variable pitch, the blades will continue to try to lift after engine failure and give up all their inertia quickly...
Unless you can manage to flip it over on the way down, then flip it back again for landing. I'd pay to see that.
Josh:
That depends on the helo, I guess. But generally, it is a combination. If you transition to autorot in normal forward flight, the rotor is already spinning and of course it doesn't stop dead if the engine stops. But the airflow takes over pretty much immediately. If your engine dies while hovering or in slow forward flight, the inertia will have to carry the rotation a bit longer, so you can build up enough forward speed.
My point was, that many people think that inertia is the ONLY reason for the rotor to spin while autorotating and that is definitely not the case.
I can see the use of Multi 4 or more vari pitch hubs being coupled to a central Petrol /Gasser motor drive system ..then we could fly for hours on missions !! I guess I had better modify a bunch 600 heli rear rotor hubs and stick them onto something using either belt drive or shaft drive units..and use servos to drive the pitch from the APM
Is it B? :-)
For instance, most helos have a freewheeling unit which decouples the engine automatically when it fails.
Then there is a common misconception that only the inertia keeps the rotor spinning. That is not the case! The airflow on an forward descent also makes the rotor spin. The faster the forward speed, the higher the lift (up to a maximum after which the lift goes down again), so if you have enough air under your skids, you can glide quite a bit.
That is, by the way, how an autogyro flies. It's rotor is not powered (not counting any prerotation mechanisms). The rotor is just turned by the airflow and as such generates lift.
See also http://en.wikipedia.org/wiki/Autorotation_%28helicopter%29
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