Promising high-speed helicopter (PSV)

Hole wrote:High-speed projects from Kamow:

The Ka-90 is a cool science-fiction concept but I think the lower pic of the transport helicopter has a rear propeller and a rigid rotor doesn't it? That would be pretty much that... For Kamov it should be easier than anyone to modify the coaxial rotor for a fast helicopter concept since they have decades experience operating them. The Ka-52's fuselage would be reusable to a high extent

Hole wrote:There is a military version of the PSV called PSSTDV = future high-speed medium transport and assault helicopter. Like a Mi-24/-35 on steroids.

Do you casually have links???

LMFS wrote:Do you casually have links???

It is mentioned in this PDF i found after a quick search.

https://vtol.org/files/dmfile/RussiaChinaOmelchenko1.pdf

Meantime, it was clarified at MAKS that the Ministry of Defence is backing the research of the military high-speed rotorcraft. The Commander-in-Chief of the Russian Aerospace Forces, Colonel General Viktor Bondarev, stated that the program is proceeding “full speed ahead.” Two high-speed programs are being funded: the UVK attack helicopter (Udarny Vertolyotny Kompleks – Strike Helicopter System) and medium-sized PSSTDV transport (Perspektivny Sredny Skorostnoy Transportno-Desantny Vertolyot – Advanced High-Speed Medium Utility Helicopter), the latter reportedly based on the PSKV civil design.

Cheetah wrote:

LMFS wrote:Do you casually have links???

It is mentioned in this PDF i found after a quick search.

https://vtol.org/files/dmfile/RussiaChinaOmelchenko1.pdf

Meantime, it was clarified at MAKS that the Ministry of Defence is backing the research of the military high-speed rotorcraft. The Commander-in-Chief of the Russian Aerospace Forces, Colonel General Viktor Bondarev, stated that the program is proceeding “full speed ahead.” Two high-speed programs are being funded: the UVK attack helicopter (Udarny Vertolyotny Kompleks – Strike Helicopter System) and medium-sized PSSTDV transport (Perspektivny Sredny Skorostnoy Transportno-Desantny Vertolyot – Advanced High-Speed Medium Utility Helicopter), the latter reportedly based on the PSKV civil design.

Very interesting Cheetah, many thanks

Is it only me or the Alligator has prime conditions to be turned into a high speed helicopter with relative ease? Compare the render below with Sikorky's twin rotor + propeller proposals:

I think you're right yes.

I'd not thought of directly reworking Ka-52 airframe like that but those renders show its a pretty viable concept
It's the sort of thing I'd have expected to have seen rather than that barely reworked Mi-24 demonstrator though.

Would need a bit more effort than just sticking props on the back though: you need engines & drive shaft to power the prop/s also and harder from my understanding you need to have more rigid hub & rotors for the higher speeds (presumably the key work thats been done with the Mi-24 demonstrator)

So, researching a bit...

It seems Kamov and Mil are competing for the attack (UVK) and transport (PSSTDV) versions of the high speed military helicopter, so in essence quite similar to US efforts. Apparently prototypes were expected to fly this year but the lack of new would indicate the project is progressing slower as planed.

Below models of the Ka-92 and Mi-X1.



The advanced blade developed with TsAGI apparently can be retrofitted in existing helicopters and provide a 10% increase in speed.

Due to matters like retreating blade and main rotor torque, I think the Kamov approach is more promising. The following would make sense to me, at least technically:

> Advanced blades in the existing Mil models as short term improvement
> Rigid rotor + propeller technology for Kamov as mid and long term solution, with speeds above 500 km/h and big ranges (>1400 km expected for the Ka-92)

hoom wrote:I think you're right yes.

I'd not thought of directly reworking Ka-52 airframe like that but those renders show its a pretty viable concept
It's the sort of thing I'd have expected to have seen rather than that barely reworked Mi-24 demonstrator though.

The Ka-50 (V-80) was designed as a high speed helicopter originally, therefore the fuselage is very aerodynamic already:



They were already on those early days thinking about 500-600 km/h and very advanced concepts to improve its agility:

https://www.aex.ru/docs/1/2014/9/16/2118/

Like said above there is one improvement related to the rotor blades that allows a marginally faster conventional helicopter. This would make sense to improve exiting fleet or models in production (like you refer for the Mi-24) but it clearly falls short of getting all the benefits of a more advanced concept, especially in Russia this is relevant due to the geography. And with US making progress in this area they cannot allow themselves to fall far behind either.

hoom wrote:Would need a bit more effort than just sticking props on the back though: you need engines & drive shaft to power the prop/s also and harder from my understanding you need to have more rigid rotor hub & rotors for the higher speeds (presumably the key work thats been done with the Mi-24 demonstrator)

Agree, a very deep rework would be necessary for the horizontal propulsion and rotor. But this could be used to modernize the Ka-52, which is a rather old concept after all while many other areas of the aircraft could be kept.

The advanced rotor developed in the Mi-24 based demonstrator is IMHO not critical for the solution with propellers, since a fast speed of the main blades is not needed to generate horizontal thrust: in a counter-rotating configuration the fact that the retreating blade does not generate lift at all is not a problem since it is compensated with the additional rotor. In fact the rotation speed of the rotor diminishes in the Sikorsky X-2 with the increasing air speed. So no design for transonic blade tip is necessary. It would be also interesting to see the aerodynamic advantages derived from improved AoA of the fuselage, as the main rotor has no role generating horizontal thrust.

I had thought a counter-rotating propeller would allow to control the torque in the longitudinal axis, partially compensating the substitution of the original rotor with a rigid one, but thought it was mechanically complex. Interestingly the Ka-92, contrary to US prototypes, incorporates this solution.

If they see viability in modifying the Ka-52 with these technologies they could get a system in a relative short period of time and little money, with great advantages. Imagine for instance the capacity increase of a naval version with so much more speed and range. That would be a breakthrough indeed

Wow  
Reminds me of the NOTAR LHX concept I always really liked

Below models of the Ka-92 and Mi-X1.

First time I've seen that Mi-X1, hmm.

I really hope that they're not really expecting Ka-90 to work, like I previously posted US has tried that concept repeatedly & not even got close to a transition, not impossible that the Russian engineers are better & successful but its unlikely.

Mi-X1 is basically same concept as X-49 which while it seems to work, its always diverting most of the tail thrust sideways, looks hacky  & awkward (to be fair it is just a hacky SH-60 conversion but I don't see how a dedicated build wouldn't still have the same issue, the basic physics of a single rotor dictate you need a big anti-torque effort, Euro X3 concept has similar issue)

Ka-92 looks great but also seems to be really large: 30 passengers is Chinook class, doesn't seem like a suitable base for new attack chopper or naval chopper that I'd have expected to be part of the program.
US S-97 looks really on the money (it is small but the concept for the bigger version also looks very good)

Which design?
The most recent folding blade type concept was a recent carbon composite UAV X-50A.


X-49 & S-97 are part of the current program for new gen US choppers.

The LHX concept is really really old & long since abandoned, pulled out of/excluded from (Army said 'conventional only') the competition for what became the cancelled Comanche. I just think thats a hell of a cool concept.

hoom wrote:Wow  
Reminds me of the NOTAR LHX concept I always really liked

Yeah that was also a favourite of mine... looks like a "supersonic" helicopter . With high speed requirements the new designs will look IMO closer to that.

First time I've seen that Mi-X1, hmm.

I really hope that they're not really expecting Ka-90 to work, like I previously posted US has tried that concept repeatedly & not even got close to a transition, not impossible that the Russian engineers are better & successful but its unlikely.

Mi-X1 is basically same concept as X-49 which while it seems to work, its always diverting most of the tail thrust sideways, looks hacky  & awkward (to be fair it is just a hacky SH-60 conversion but I don't see how a dedicated build wouldn't still have the same issue, the basic physics of a single rotor dictate you need a big anti-torque effort, Euro X3 concept has similar issue)

Ka-92 looks great but also seems to be really large: 30 passengers is Chinook class, doesn't seem like a suitable base for new attack chopper or naval chopper that I'd have expected to be part of the program.
US S-97 looks really on the money (it is small but the concept for the bigger version also looks very good)

Ka-90 and all those high-risk projects... I am not holding my breath for them. Development goes step by step, not four steps at a time. First, decouple lift from horizontal thrust. Then, see how far you can go. Maybe rotor blades grow so big and so slow that you can handle them like wings or can put a radar antenna inside and rotate them relatively slow for an AWACS helicopter... who knows??

Mi-X1... agree, I don't see the advantage apart from more conventional design and lower profile of the main rotor. As you say it looses propulsion power and is cumbersome due to anti-torque function of the tail. And besides the retreating blade issue is not solved in such design so not cleat to me it can be as fast as the Kamov's design.

The Ka-92 has roughly the size of the EH-101 so big but within the range of a medium-sized transport helicopter... the  project was apparently destined to civil market to link remote areas, oil platforms for instance, and was moved to the defence ministry afterwards due to funding. Due to the range, it makes sense to make the helicopter big. I expect an attack helicopter to be clearly smaller of course...

For the Mi-X1 it is relevant to consider the SLES system, I was not aware of this though it is an old issue:

The Mi-X1 is being developed for a cruise speed of 257kt and maximum speed of 280kt using an innovative main rotor design with computer control. Mil is working on a system to suppress local stalls on the retreating blade. Such high speed would be achieved by applying a technology called the Stall Local Elimination System (SLES) in the main rotor. SLES delays the stall on the retreating blade through the control of its orientation angle. According to Mil calculations, the SLES should work well at speeds of up to 400 km/h. To delay the blade stall at higher speeds, Mil suggests a combination of the SLES technology with an arrow-type shape to the blade tip. Contributing to the helicopter's speed is the potential use of a tail-mounted propeller with thrust vector control via surfaces installed in slipstream.

https://www.globalsecurity.org/military/world/russia/mi-x1.htm

Possibly the Kamov concept? http://charly015.blogspot.com/2018/10/es-esta-la-propuesta-de-kamov-de.html



Pretty radical, I like it!

A very unconventional powerplant config.
Rather than a prop for propulsion its using jet exhaust, more than just a normal chopper turbine.
Seems to have a high-bypass turbofan type setup & a drive-shaft for the rotors off the front.

Problem with that setup is you'll always be dealing with a lot of forward thrust, maybe the fans are de-couplable or its got thrust reversers?
S-97 has a fairly conventional variable pitch prop so can easily set it neutral/reverse which may make it more practical.

Edit: more from Balancer


Yep turbofans with a drive-shaft off the front for rotors

hoom wrote:
Problem with that setup is you'll always be dealing with a lot of forward thrust, maybe the fans are de-couplable or its got thrust reversers?
S-97 has a fairly conventional variable pitch prop so can easily set it neutral/reverse which may make it more practical.

The solution may not be as complex and daunting as you make it out to be. In my honest opinion the solution is for a certain speed (650 km/h or greater) the helicopter blades slow down to a stop, angle backwards and lock in place and act like wings that provide lift allowing the aircraft to fly like a normal jet-aircraft, and unlock and restart like normal when the vehicle slows speed below 300 km/h.



Also this is where very few places that VSTOL design experience can improve the aircraft. Perhaps Yakovlev design bureau can contribute to the design, say perhaps add a small internal jet engine located at the bottom of the aircraft, that thrust vectors downward to provide upward thrust when the aircraft transitions from working rotors to static rotors, or vice versa. I wonder if 3D-TVC could be added to the main jet engines?

The solution may not be as complex and daunting as you make it out to be

Thrust reversers or de-coupling fans is a vastly more simple & practical solution than stopping/starting rotors in flight (& finding a workable airfoil section for the rotors).

As I mentioned further up the thread the US has thrown loads of money at the idea across multiple decades with 0 success, its not impossible that Russian engineers would be more successful but surely extremely unlikely.
IMO spending any of the limited available money/effort on it is surely wasted when it could be spent on a solution thats actually likely to work.

Cockpit section looks similar to that of the Ka-52. Maybe they are already cutting a prototype of the Ka-52 into pieces in the prototype shop at Kamov.

I was thinking that too.

A downside of those huge wings is it blocks a lot of the downwash from the rotors -> will impact the hover/lift ability.

Great info hoom, thanks for the additional pictures of this solution

Well, this is as close as a helicopter can get to a plane I guess. Even the propulsion solution is essentially like the one on F-35B  

Regarding what you say about the forward thrust issue, I guess the amount of forward moment transferred to the plane depends on the moment of the gases being expelled. If the engine is designed so that the turbine manages to extract almost all kinetic energy from the gas going though it then the forward thrust would be minimal, maybe somebody with actual knowledge on jet engines can comment on that. In any case the solution is amazing, way more advanced than the propeller solution and apparently capable of incredible speeds. A helo going 700 km/h is not what is understood as a helo any more, especially if it is equipped with such wings, most probably it will be capable of manoeuvring quite harder than a conventional design and carry more load further. Maybe the issue you mention with the wing area and its interference on vertical take off is real and the aircraft uses the forward thrust to take-off while in forward motion?

Massive advance for so many applications, cannot see the moment we know more a bout this new idea

What do you mean with decoupling fans to avoid forward thrust?

BTW, Kamov has been literally working on a high speed helo for decades, see below from the Hokum development:

see below from the Hokum development:

Yes I think this is a descendant of that.

If the engine is designed so that the turbine manages to extract almost all kinetic energy from the gas going though it then the forward thrust would be minimal

Yes, its my understanding most turboprops/chopper engines leave little energy to provide thrust, many still use that little extra.

But this concept has large diameter high-bypass engines intended to provide thrust for the high speeds & that then needs to be controlled somehow at lower speed because you need to keep the engines at high power to provide the rotor lift.
S-97 concept with a variable pitch prop has good & direct control without needing any exotic engineering.
The Hokum concept would have similar direct control either by feathering or de-coupling the fan in the tail.


There is also the possibility this is a promo/disinfo leak & actual effort is going elsewhere.

@hoom:

Ok I see what you mean. Maybe the bypass channel can be closed when hovering is needed.

I like the concept, seems simple while the stated speed is so much above other high-speed designs that it may open the possibility of taking the roles of fixed wing aircraft like Su-25

This thing could replace su-25 and ka-52. Mi-28 would be kept as traditionnal helicopter. New su-25 no needed anymore so they buy more fighter/bombers for real bombing missions like mig-35.


In reality they will keep buying ka-52 and mi-28 and this new kamov will be too much. Like t-14 with t-90/80/72 upgrades being good enough. Or su-57 with flankers.

Someone at Balancer posted this patent which seems to be describing same concept https://patents.google.com/patent/RU168554U1/ru

Apparently there has been a flight demonstrator Ka-35D which used a separate drive engine & unpowered the rotors at high speed, switching to auto-rotation -> autogyro flight.
Seems to have failed because auto-rotation gets really draggy at high speed.

They don't like S-97 concept because it requires rigid rotor, still has limitations from advancing blade tip speed.

This new concept uses the wings to almost completely de-load the rotor, the drive to rotors is decreased but not completely eliminated, rotor speed reduced to minimal required to keep the rotor stable -> no advancing blade issues & doesn't need to switch to a rigid rotor.
Says the jet/nozzle is configurable to provide minimal thrust for hover, high thrust for high speed.