Are HYBRID helis the future of rotorcraft?

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autoreply

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The problem with helicopters is they are mission oriented. They are pickup trucks or work vehicles of the sky. Helicopters are the blue collar of aviation. You will not have a useable aircraft, if you can't hover on demand. You tend to break a bunch of rules with helicopters as hover over the top of trees or mountain ledges or over lakes; high hovers for news crews. Some hover a tank of fuel at a time. We have a helicopter that was the in car camera signal relay for NASCAR in the 80s. It hovered over the tracks until it needed fuel. Our use is observation platform, on a two hour flight we can stop and hover 50 plus times to get pictures. Sometimes only a couple of times. For the most part cruise is secondary importance. EMS want speed and oil platforms want distance. Tilt rotor is really a small market, they are not good helicopters and they are not good airplanes. They do work when you need to go far for a hover, but they have quirks that don't make them better than regular helicopters.
Scale favors small tiltrotors (low disk loading).

Admittedly, tiltrotors will never be very efficient for missions that require hovering for a large portion of the mission; however, a tiltrotor can be an enabler for mission with little hover (go from A to B).

Electric motors have such an extreme power density (5-10 kW/kg) that even turboprops are left in the dust; once you figure in the weight of the gearbox and all systems, you have at best half the power for a given engine weight.


Helicopters are far from my area of expertise - or even competence - but I have to mention that the market overall agrees with Don. Compound helicopters (lift rotor + forward-propulsion prop(s)) have been areas of active experimentation since the 1950's. Even ones that converted to a gyrocopter after takeoff and put all the engine power through the forward propulsion propeller(s); the Fairey Rotodyne comes to mind immediately.

Yet none of these have broken into commercial success, very likely for the simple reason Don's putting forward: Once you have VTOL capability, payload weight is far more important to the operator than cruise speed. Where compound helicopters have seen serious consideration was for various very specific niche missions, but that doesn't apply to a general-purpose rotorcraft.

A tilt-rotor is probably the best of all possible worlds, but is hugely complex even when compared to a compound helicopter, and suffers a lot of compromise in VTOL payload capability - much of the "potential" payload is sucked up by having to lift the wing and tails. The V-22 Osprey has a very specific and extreme mission-set to justify its existence, which just isn't there in the homebuilt world.

Making it an ICE-electric hybrid doesn't change any of this.

I'm sure it can be done, but it's genuinely a case of why would you do it?
A major part of the trouble of the Osprey was in it's initial design. To fit within existing dimensions, both the wing and disk loading are very high and consequently payload and range is pretty depressing. The Dream machine gives a good account of what that resulted in.

The V280 Valor and the small AW609 will hopefully prove to be much less of a constrained design.
 

dino

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Actually in cruise a mix of about 15% power to rotor and 85% to prop is more efficient. This type of aircraft is called a gyrodyne.
 

Himat

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I'm sure the workers would appreciate speed over everything else, no doubt. However, the company, who is paying the bill to get them out there, likely wants every possible pound out there at the lowest possible cost. In aircraft design, that generally means slower than the highest speed possible. The trade between fuel economy and payload is likely a little different than it is with airplanes, but I would strongly guess that it still favors a conventional rotorcraft, without the added complexity and reduced payload of a compound type.
I do remember that the capabilities of the Augusta Westland A309 as an oil rig crew change vehicle was questioned almost from the start. The nine passenger capacity considered to be to small. When I was travelling offshore, the Sikorsky S-76 and Eurocopter AS365 were of the “small” helicopters used. I think they usually did have ten or twelve seats.

Long distances were almost always with some of the larger 18 seat helicopters. And those long flights was not that common as not that many oil fields is that far offshore. Could be that this market is to small altogether to specialise in.
 

EzyBuildWing

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Watch the fantastic "electric-start" at the begining of this "Hungarocopter" vid:
https://www.youtube.com/watch?v=X8tUT74YgWo
Powerful electric motor pre-spins the rotor up to rated-speed at zero-pitch, then petrol-engine starts up and takes over 100%.
Electric motor then charges the battery.
If petrol-engine quits, then electric motor immediately kicks in for a few minutes thus enabling a (semi)power-on decent, and a smooth flared landing.
Google "Hungarocopter" for pics of the electric motor-generator. It's very elegant.
It would be nice to see such a heli powered with a lightweight Aluminium "peripeheral-ported" 13B Mazda Wankel.
That these engines are tough, is an understatement!
Check this for time-to-climb record: 10,000 ft in 100 seconds!
https://www.youtube.com/watch?v=k_gedJrWbT4
 

EzyBuildWing

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Sydney NSW Australia
Hybrid Heli? ...well almost! new Hungaro Heli has "electric rescue-system" .... if main-engine quits, stand-by electric motor kicks-in and enables a couple of minutes of controlled powered-decent.

https://www.youtube.com/watch?v=X8tUT74YgWo This AWESOME sounding vid shows the electric-motor pre-spinning the lift-system, prior to main-engine start-up. This sounds better than a JetRanger!

https://www.youtube.com/watch?v=hnsYuEfX5Jg "Electric rescue-system" practical demo from the cockpit....works brilliantly!
 

EzyBuildWing

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re: Hungaro Copter:

Maybe ditch that heavy old Subaru petrol-motor, and install a larger 130hp Electric motor plus more batteries and a simple "AixroWankelGenerator"(as a 7000rpm super-smooth range-extender).

Google e-Genius for details of this motor-generator arrangement or click this Link: http://sustainableskies.org/e-genius-extends-range/

"We will design a custom engine and generator specified specifically for the P2. Power out in the prop is 100kW (approx. 130HP) and the generator will produce 57-60kW of power charging the batteries. The combustion engine will be a Wankel engine that runs on bio-diesel fuels and jet-fuel. The fuel tank can hold 100l and this should give you a flying time of 5-6 hrs. max.”
 

EzyBuildWing

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henryk

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krakow,poland
Conter Rotating propellers ?
IMG_20171218_160454751.jpg


-gearless ,reactionless circa 50 kW electric drive motor + Conter Rotating rotors

+ICE engine drived electric generator +thrust propellers=VTOL hybrid device ,
moore economical in comparation with classic autogyro !
 

D Hillberg

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very low low low earth orbit
-moore simple?(for my understanding...)

PS=1.3 m heli rotors get us up to 15 kG/kW ! (specific thrust)
1.3 m rotors = no autorotation disk loading too high
fixed pitch = no auto rotation

you're a bowling ball enjoying the effects of gravity if you encounter any failure mode requiring autorotation...and there a lot of failures needing pitch control
 

henryk

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krakow,poland
1.3 m rotors = no autorotation disk loading too high
fixed pitch = no auto rotation

you're a bowling ball enjoying the effects of gravity if you encounter any failure mode requiring autorotation...and there a lot of failures needing pitch control
1.3 m rotors=from heli modell, for cocept examination...

real device=7 m gyro rotor(permanently in autorotation),constant AoA...50 kW electric power for take off and hovering,
circa 5 kW electric + 30 kW ICE in cruise regime.

http://www.reaa.ru/yabbfiles/Attachments/PICT4970.JPG
 
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henryk

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krakow,poland
Scaling up often yields poor results. You'll need lower disk loading or more electric motor....


(use less steel and plastic - use more aluminum
-we was preliminary tested 7m gyro rotor gearless drived by 20 kW electric motor
(154-120)...its a pity, at 10 kW (100 V, 100 A) some coils was burned !

now we have double 40 kW motors (202-120) +two 500 A controllers, ready for testing.

^FC2CFDD1E824F8FB4A52F1E4506FB2110AEAFE42B9D9BE9FC1^pimgpsh_fullsize_distr.jpg IMG_20171219_124709075.jpg
 
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