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 do though like the idea of the variable pitch quadcopter, only of there was a flight controller that could go with it, but could be in the market within a few years perhaps.
Everything I've learned and experienced indicates that multi-blade props are significantly less efficient than conventional two-bladed ones. And the bigger the better. The reason they're used on airplanes is for ground and or fuselage clearance. Three, four and five-bladed props look cute on scale airplanes, but that is all. As an aside, most of the 2-bladed props we all use are designed to provide thrust for airplanes, not rotary-wing craft. There is a whole lot of work to do in this regard.
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.
@Stefan
It's a combination of both right? My understanding was if you start dropping at 1000' you won't have enough time to build up your rotor speed from the air flow alone no?
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