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    5th gen Combat Helicopter for RuAF

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    OminousSpudd
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    Re: 5th gen Combat Helicopter for RuAF

    Post  OminousSpudd on Tue May 24, 2016 7:05 am

    Werewolf wrote:
    Could someone explain what is meant by this? I have never heard of the concept before.
    The concept is a rotor system with folding blades while flying. The concept is to fly like a normal helicopter and as soon as it reachs its flight speed of transition the rotor blades become small wings and are extented from the body and keep folding further back in tailboom position, the higher the speed. The concept more or less for high speed like on Su-24 like jets with wings that are extented in slow speeds to produce lift but with higher speeds lift is enough but the friction of the extented wings are getting a hinderance so they swing them back to reduce friction and increase with it potential for speed. A concept that in theory sound great but is coupled with enormous problems of a developing a rotor head that can produce lift and then transform to wings without affecting the flight itself to the negative, let alone actually produce enough lift in its folded design.
    Ahh, sounds interesting thank you Werewolf. I'd assume that given the amount of engineering the V-22 Osprey had simply to get that VTOL/STOL capability on turboprops, and even then with the final product being abysmal at best, that the concept you described is indeed a nightmare. Mind, that was a US defense project, not exactly known for reliability or cost effectiveness.

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    Re: 5th gen Combat Helicopter for RuAF

    Post  PapaDragon on Tue May 24, 2016 8:44 am

    OminousSpudd wrote:.................
    Ahh, sounds interesting thank you Werewolf. I'd assume that given the amount of engineering the V-22 Osprey had simply to get that VTOL/STOL capability on turboprops, and even then with the final product being abysmal at best, that the concept you described is indeed a nightmare. Mind, that was a US defense project, not exactly known for reliability or cost effectiveness.

    If they can figure out some simple and rugged system to handle the folding part it could be done but holy hell it will be tall order.

    hoom
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    Re: 5th gen Combat Helicopter for RuAF

    Post  hoom on Thu May 26, 2016 5:12 am

    In-flight transition to folded rotors seems incredibly unlikely.
    US has been experimenting with that kind of thing for ages, neither Sikorsky S-72 nor the more recent Boeing X-50 got close to transitioning from rotor to fixed let alone folding in-flight.

    With US/EU both apparently heading toward contra-rotors + pusher & Russia already having lots of operational experience with contra-rotors, I'd be hoping that they are heading along that fairly conservative line instead.

    GarryB
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    Re: 5th gen Combat Helicopter for RuAF

    Post  GarryB on Thu May 26, 2016 1:12 pm

    Inflight folding rotors is a stupid idea... when the rotors start to fold they will stop generating lift and the aircraft will drop like a stone.

    If you mean automatically folding rotors where you land and then press a button and the rotors fold up automatically then the Ka-25 and Helix series has been doing that with coaxial rotors for half a century...



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    Re: 5th gen Combat Helicopter for RuAF

    Post  x_54_u43 on Thu May 26, 2016 3:11 pm

    GarryB wrote:Inflight folding rotors is a stupid idea... when the rotors start to fold they will stop generating lift and the aircraft will drop like a stone.

    If you mean automatically folding rotors where you land and then press a button and the rotors fold up automatically then the Ka-25 and Helix series has been doing that with coaxial rotors for half a century...


    Seriously? The concept of in flight folding rotors is to allow for a speed increase, the lift generation would have been provided by other fixed wings or by a lifting body at sufficient speeds.

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    Re: 5th gen Combat Helicopter for RuAF

    Post  Werewolf on Thu May 26, 2016 7:23 pm

    hoom wrote:In-flight transition to folded rotors seems incredibly unlikely.
    US has been experimenting with that kind of thing for ages, neither Sikorsky S-72 nor the more recent Boeing X-50 got close to transitioning from rotor to fixed let alone folding in-flight.

    With US/EU both apparently heading toward contra-rotors + pusher & Russia already having lots of operational experience with contra-rotors, I'd be hoping that they are heading along that fairly conservative line instead.

    Yes, the problems with such a design would be several times fold. The intertial momentum from blades turning have to be compensated immidiatley to fold them up to provide fixed-wing like lift within a very small time or they will take forever to compensate and transform from rotating to fixed wings forever and will drop like stone. The solutions to both are no solutions at all.  Either fatal result with death of machine and occupants from slow transformation from rotating to fixed wings or immense logistical, economical and matter integrity point of view.

    I can not imagine to have such system work whatsoever, not without fixed wings installed on it like on UH-60 schnellsky prototype or Mi-24 generating lift, stubbed wings with extented and more dedicated purpose to do so, but that would bring the entire KA-90 scheme to a dead end. So why propose such a scheme in first place?

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    Re: 5th gen Combat Helicopter for RuAF

    Post  Zivo on Fri May 27, 2016 1:03 am

    Werewolf wrote:

    Yes, the problems with such a design would be several times fold. The intertial momentum from blades turning have to be compensated immidiatley to fold them up to provide fixed-wing like lift within a very small time or they will take forever to compensate and transform from rotating to fixed wings forever and will drop like stone. The solutions to both are no solutions at all.  Either fatal result with death of machine and occupants from slow transformation from rotating to fixed wings or immense logistical, economical and matter integrity point of view.

    I can not imagine to have such system work whatsoever, not without fixed wings installed on it like on UH-60 schnellsky prototype or Mi-24 generating lift, stubbed wings with extented and more dedicated purpose to do so, but that would bring the entire KA-90 scheme to a dead end. So why propose such a scheme in first place?

    Autorotation during the transitional phase may be adequate enough to maintain lift even while the drive is disconnected, allowing for a much larger transitional window.

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    Re: 5th gen Combat Helicopter for RuAF

    Post  Werewolf on Fri May 27, 2016 1:10 am

    Zivo wrote:
    Werewolf wrote:

    Yes, the problems with such a design would be several times fold. The intertial momentum from blades turning have to be compensated immidiatley to fold them up to provide fixed-wing like lift within a very small time or they will take forever to compensate and transform from rotating to fixed wings forever and will drop like stone. The solutions to both are no solutions at all.  Either fatal result with death of machine and occupants from slow transformation from rotating to fixed wings or immense logistical, economical and matter integrity point of view.

    I can not imagine to have such system work whatsoever, not without fixed wings installed on it like on UH-60 schnellsky prototype or Mi-24 generating lift, stubbed wings with extented and more dedicated purpose to do so, but that would bring the entire KA-90 scheme to a dead end. So why propose such a scheme in first place?

    Autorotation during the transitional phase may be adequate enough to maintain lift even while the drive is disconnected, allowing for a much larger transitional window.

    That would require a high altitude transition, since you would still lose altitude during autorotation and then you would still have a time window where the folding mechanism has to adjust itself from rotating to fixed wing, if that happens with instant movement it has to compensate the momentum which is a big concern aswell if it takes to much time then it will either tilt or lose to quick altitude. Either way, not an easy concept not even in theory.

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    Re: 5th gen Combat Helicopter for RuAF

    Post  Zivo on Fri May 27, 2016 2:54 am

    Werewolf wrote:
    Zivo wrote:
    Werewolf wrote:

    Yes, the problems with such a design would be several times fold. The intertial momentum from blades turning have to be compensated immidiatley to fold them up to provide fixed-wing like lift within a very small time or they will take forever to compensate and transform from rotating to fixed wings forever and will drop like stone. The solutions to both are no solutions at all.  Either fatal result with death of machine and occupants from slow transformation from rotating to fixed wings or immense logistical, economical and matter integrity point of view.

    I can not imagine to have such system work whatsoever, not without fixed wings installed on it like on UH-60 schnellsky prototype or Mi-24 generating lift, stubbed wings with extented and more dedicated purpose to do so, but that would bring the entire KA-90 scheme to a dead end. So why propose such a scheme in first place?

    Autorotation during the transitional phase may be adequate enough to maintain lift even while the drive is disconnected, allowing for a much larger transitional window.

    That would require a high altitude transition, since you would still lose altitude during autorotation and then you would still have a time window where the folding mechanism has to adjust itself from rotating to fixed wing, if that happens with instant movement it has to compensate the momentum which is a big concern aswell if it takes to much time then it will either tilt or lose to quick altitude. Either way, not an easy concept not even in theory.

    With a pusher engine, you shouldn't lose altitude like a normal helicopter. When the power is cut to the main rotor, the Ka-90 would essentially operate as a gyrocopter. The rotors could be slowed through braking to form a horizontal wing, but there's no way to say whether or not a transition done this way is viable, until it's actually tested.

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    Re: 5th gen Combat Helicopter for RuAF

    Post  Werewolf on Fri May 27, 2016 11:00 am

    Yes, i aggree. I just have problems with that concept of Ka-90 without having details nor the parts we talked about to accomplish such technology. Let's see what they come up with or if they drop this concept all together.

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    Re: 5th gen Combat Helicopter for RuAF

    Post  GarryB on Sat May 28, 2016 10:29 am

    Seriously? The concept of in flight folding rotors is to allow for a speed increase, the lift generation would have been provided by other fixed wings or by a lifting body at sufficient speeds.

    Ahh, you are talking about a Ka-90 type that has rotor blades that can be used as swept wings at high speed... has that ever actually been done?

    Thing is that the main problem there is that an aircraft wing is wide to be effective as a fixed surface... and a helicopter blade is narrow and there are lots of them... most Kamovs have two sets of three blades so a total of 6 blades... you not only have to stop them in flight but also get them to all generate lift at the same time as they fold together... sounds incredibly complex and ultimately fruitless.

    Leave helos and helos and use fixed wing aircraft.


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    George1
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    Re: 5th gen Combat Helicopter for RuAF

    Post  George1 on Sat May 28, 2016 12:08 pm

    Ka-90 i think its a civilian project


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    Re: 5th gen Combat Helicopter for RuAF

    Post  Zivo on Sat May 28, 2016 5:38 pm

    GarryB wrote:
    Seriously? The concept of in flight folding rotors is to allow for a speed increase, the lift generation would have been provided by other fixed wings or by a lifting body at sufficient speeds.

    Ahh, you are talking about a Ka-90 type that has rotor blades that can be used as swept wings at high speed... has that ever actually been done?

    Thing is that the main problem there is that an aircraft wing is wide to be effective as a fixed surface... and a helicopter blade is narrow and there are lots of them... most Kamovs have two sets of three blades so a total of 6 blades... you not only have to stop them in flight but also get them to all generate lift at the same time as they fold together... sounds incredibly complex and ultimately fruitless.

    Leave helos and helos and use fixed wing aircraft.

    I believe the Ka-90 has just two wider-than-normal blades.

    When an airfoil is being designed, it has to be able to generate enough lift at low speed to get the aircraft off the ground during takeoff. But at higher velocity, less surface area is needed to generate the same amount of lift. Since the Ka-90 takes off like a helicopter, it doesn't have the same low velocity lift requirements, so the blades wont need much surface area. Cruise missiles only need stub wings for the same reasons.

    Ka-90 i think its a civilian project

    I think it's a demonstrator, proof of concept.

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