Are HYBRID helis the future of rotorcraft?

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Doggzilla

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Recently we had a discussion about electric and hybrid fixed wing aircraft, and it recently occurred to me that the hybrid tech which is only marginally useful in fixed wings would be exceptionally useful for rotor craft.

The newest generation of rotorcraft have drive props or jets attached to them, and it increases performance a significant margin. Hybrid motors can do the same for a fraction of the weight and complexity.

For instance, it allows a single motor to be used as a power source, and allows the full power to be diverted between the rotor or thrust motors.

The weight of the electric motors is exceptionally light, often less than the transmissions they would replace. And thats not counting the weight savings from removing a second powerplant.

It also allows the helicopter to be designed with far more performance and safety in mind, as the generator can be installed behind the crew compartment instead of over it. This would significantly improve balance and aerodynamics.

Hybrids might not be a big improvement for fixed wing, but they would be an absolutely huge improvement for rotorcraft.
 

Mad MAC

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There might be a use as a new form of tip jet i.e. electric driven ducted fan or prop at the rotor tip.

I am not sure that electric power transmission is yet lighter than mechanical power transmission well for most rotorcraft configurations.
 

TFF

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Helicopters consume a lot of power. Unless you are flying a turbine on the empty side of gross, you are using lots. A hover takes at least 80% of all power. Maybe 90%. An airplane can fly around on 10% power; maybe not fast, but can fly. A helicopter is using 50% or it goes down. Military or high end helicopters have excess, but a L1 LongRanger and down are underpowered requiring finesse to fly. In a helicopter if you demand 100%, you better have it. You cant stay in the air if the batteries are on the down side and all you have is the engine left on a hybrid. Not unless you can have 100% of needed power out of either sources. A hybrid would be great if you could have 100% from the regular engine and then 25% from an electric on demand. You can never have too much power in a helicopter. The one reason a turbine works so good is it will make more than a piston at half the weight. On most helicopters like a JetRanger, that is a free passenger over a piston.
 

autoreply

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Helicopters consume a lot of power. Unless you are flying a turbine on the empty side of gross, you are using lots. A hover takes at least 80% of all power. Maybe 90%. An airplane can fly around on 10% power; maybe not fast, but can fly. A helicopter is using 50% or it goes down. Military or high end helicopters have excess, but a L1 LongRanger and down are underpowered requiring finesse to fly. In a helicopter if you demand 100%, you better have it. You cant stay in the air if the batteries are on the down side and all you have is the engine left on a hybrid. Not unless you can have 100% of needed power out of either sources. A hybrid would be great if you could have 100% from the regular engine and then 25% from an electric on demand. You can never have too much power in a helicopter. The one reason a turbine works so good is it will make more than a piston at half the weight. On most helicopters like a JetRanger, that is a free passenger over a piston.
Tiltrotor?

A 2-seat light aircraft can cruise at decent speeds at what, 35 SHP?
Such an airframe needs at least 3-5 times that for same hover+ a bit of climb.

100 hp per proprotor, enough batteries for 5 minutes of hover and a 50 hp generator on board and you have an application that's pretty close to ideal for a hybrid ;)
 

TFF

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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.
 

D Hillberg

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=little kWh batteries for VTOL,petrol +small electric energy via big altenator fo cruise...
Why carry stuff that takes away useful load? The operator or customer will NOT pay for items that take away from the useful load...the Load pays the bills. and you have the power to flight profile backwards. cruise takes 60 to 70% power where a takeoff at high DA or vertical reference takes 100% power.
 

henryk

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"cruise takes 60 to 70% power where a takeoff at high DA or vertical reference takes 100% power. "

= helicopter,YES!

-but in auer case cruise fly is in "autogyro" regime,with permanent mechanical rotor prerotation...much moore energy effective...
 

Doggzilla

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Tiltrotor?

A 2-seat light aircraft can cruise at decent speeds at what, 35 SHP?
Such an airframe needs at least 3-5 times that for same hover+ a bit of climb.

100 hp per proprotor, enough batteries for 5 minutes of hover and a 50 hp generator on board and you have an application that's pretty close to ideal for a hybrid ;)
Wonder what it would take to add a pair of hybrid tilt rotors to the wings of a sailplane. Mount them on the underside and have a hinge at the leading edge so the whole assembly rotates around the leading edge.

A blown wing would give a sailplane fairly extreme STOL even if it wasnt a true VTOL.
 

Doggzilla

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"cruise takes 60 to 70% power where a takeoff at high DA or vertical reference takes 100% power. "

= helicopter,YES!

-but in auer case cruise fly is in "autogyro" regime,with permanent mechanical rotor prerotation...much moore energy effective...
Yes, everyone is forgetting that rotorcraft can operate as gyros as well.
 

Topaz

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Why carry stuff that takes away useful load? The operator or customer will NOT pay for items that take away from the useful load...the Load pays the bills. and you have the power to flight profile backwards. cruise takes 60 to 70% power where a takeoff at high DA or vertical reference takes 100% power.
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?
 

Topaz

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Bell likes Tiitrotor. Sikorsky is betting on compound after the record breaking X2. http://raider.sikorsky.com/raider_technology_demonstrator.asp
Both for niche missions - oil-platform staffing/executive transport, and military, where cruise speed is considered more important to productivity than payload weight. IMHO, Don is still right, even in light of these attempts, neither of which have actually been tested in the market yet either.
 

henryk

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Dick McGraw built a Homebuilt compound helicopter (jump type autogyro called gyrhrino). Two props with shaft drive. Video https://m.youtube.com/watch?v=t6xjCUVuUzg
-it is very clever construction,but moore complicated in comparation to "clean" autogyro...

=jump regime is hasardous,dynamic motion...

-we preffer counterrotating scheme,with electric RPM full controll...
 

Himat

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Both for niche missions - oil-platform staffing/executive transport, and military, where cruise speed is considered more important to productivity than payload weight. IMHO, Don is still right, even in light of these attempts, neither of which have actually been tested in the market yet either.
If you have ever tried a two and a half hour flight in a cramped helicopter wearing an immersion suit you’ll really appreciate speed. Flying these offshore oil platform crew change missions, cruise speed and fuel economy quickly translates into payload too. Less fuel spent in cruise mode translate to more load
 

Topaz

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If you have ever tried a two and a half hour flight in a cramped helicopter wearing an immersion suit you’ll really appreciate speed. ...
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.

Given how much development work has been expended on compounds since the 1950's, if the economics were otherwise we'd almost certainly be seeing compounds in widespread use for this mission. My understanding is that the Bell-Agusta (now just Agusta) 309 tiltrotor was being pitched for oil-platform missions, but didn't get any takers, now being marketed exclusively for the executive/VIP transport mission, and to the military. Whether that's accurate or not I don't know, but that's the word I've heard. Kind of clearly points to the fact that the additional speed the 309 could give is offset by worse economics, compared to a conventional helicopter. For the oil-platform resupply mission, at least.
 
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