Hughes VHLH very-heavy-lift helicopter

hesham

hesham

ACCESS: USAP
Senior Member
Joined
26 May 2006
Messages
33,480
Reaction score
13,529
Hi,

in the late of 70s,Hughes developed the VHLH very-heavy-lift helicopter,
This helicopter, having a gross weight of about 270,0001b powered by four low-bypass-
ratio Pratt & Whitney F-100 or G.E. F-101 engines, was designed to carry the 60-ton
XM-1 Main Battle tank for a distance of 100 nautical miles in a ship-to-shore assault mission.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008694_1993008694.pdf
 

Attachments

  • Hughes.JPG
    Hughes.JPG
    36.9 KB · Views: 1,254
Please see the source;

I modified many my last topics and I put the source of the last projects in
those topics;

Piasecki PA-1
Boeing Vertol BV.166
Bolkow Bo-X
Tishchenko VTOL aircraft
Hiller Type-1108
Hughes VHLH

And again it is;
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008694_1993008694.pdf
 
hesham, thanks
 
Specific report on the Hughes VHLH including operational deployment.

Preliminary Design of a Tip-Jet-Driven Heavy Lift Helicopter Incorporating Circulation Control
This report describes a preliminary design study for a Very Heavy Lift Helicopter (VHLH) that is powered by jets at the blade tips and is controlled by circulation control applied to the main rotor blades. The main thrust of the program was to integrate a tip-jet-powered helicopter design computer program developed by Hughes Helicopters, Inc. (HHI) with circulation control data generated by the David Taylor Naval Ship Research and Development Center (DTNSRDC). This work combined the computer program integration work with an air vehicle preliminary design study to size the helicopter and describe its features. The result of this study is the sizing of a four-engined helicopter with a 185-foot-diameter, two-bladed main rotor that is designed to carry the XM-1 Main Battle Tank 100 nautical miles in a ship-to-shore Marine Corps assault mission.
Click to expand...

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA099192&Location=U2&doc=GetTRDoc.pdf
 

Attachments

  • hughes_vhlh.JPG
    hughes_vhlh.JPG
    49.4 KB · Views: 1,065
Does anyone know why hot-gas cycle propulsion is popular for heavy-lift helicopters? is it because gearbox weight grows disproportionately with power rating?
 
AeroFranz said:
Does anyone know why hot-gas cycle propulsion is popular for heavy-lift helicopters? is it because gearbox weight grows disproportionately with power rating?
Click to expand...
I suspect the manufacturing requirements and costs grow equally large at the higher power ratings.
 
AeroFranz said:
Does anyone know why hot-gas cycle propulsion is popular for heavy-lift helicopters? is it because gearbox weight grows disproportionately with power rating?
Click to expand...

I don't know about hot-gas cycle being so popular but certainly tip jet rotors (of which hot-gas is just one and probably the worst solution) have a range of significant advantages over convetnional torque rotors. No need for weighty and expensive gear boxes, no need for diverting power to counter torque and increased moment of inertia in the rotor are some of the advantages.

Because of the significant improvements in small turbojets and turbofans since the early 1960s (thanks to the missile industry) there is plenty of potential for tip jet rotors with tip mounted engines to be revisited.
 
AeroFranz said:
Does anyone know why hot-gas cycle propulsion is popular for heavy-lift helicopters? is it because gearbox weight grows disproportionately with power rating?
Click to expand...

Yes. I have a report (somewhere) that talks about that. I'll see if I can track it down tomorrow.
 
Abraham Gubler said:
AeroFranz said:
Does anyone know why hot-gas cycle propulsion is popular for heavy-lift helicopters? is it because gearbox weight grows disproportionately with power rating?
Click to expand...

I don't know about hot-gas cycle being so popular but certainly tip jet rotors (of which hot-gas is just one and probably the worst solution) have a range of significant advantages over convetnional torque rotors. No need for weighty and expensive gear boxes, no need for diverting power to counter torque and increased moment of inertia in the rotor are some of the advantages.

Because of the significant improvements in small turbojets and turbofans since the early 1960s (thanks to the missile industry) there is plenty of potential for tip jet rotors with tip mounted engines to be revisited.
Click to expand...

The problem with sticking turbine engines out at the tips is the weight out at the blade tip (causing the blade to have to be strong), drag, and trying to operate those turbines in a high G field. Not impossible but certainly down the list of possiblities a ways.
 
The ill-fated efforts with DARPA's heliplane (http://www.darpa.mil/TTO/Programs/h...insurmountable now as they were back then. ]
 
sferrin said:
The problem with sticking turbine engines out at the tips is the weight out at the blade tip (causing the blade to have to be strong), drag, and trying to operate those turbines in a high G field. Not impossible but certainly down the list of possiblities a ways.
Click to expand...

Yet these issues pale into insignificance compared to the complexity of building high powered gear boxes and ducting for hot gas to a rotor tip. Turbine operation in high G has been demonstrated and rigid rotors are not so bad. The worse thing is high drag for autorotation. Though this just creates a different – not worse – flight profile. The drag could be countered by some kind of streamlined nose closing over the inlet when autorotating.
 
The problem with sticking turbine engines out at the tips is the weight out at the blade tip (causing the blade to have to be strong), drag, and trying to operate those turbines in a high G field. Not impossible but certainly down the list of possiblities a ways.
Click to expand...

'Bear of very little brain moment tm' Do the engines_have_ to be tip mounted? How about moving them in to say, blade mid-span?
Sure, there'd be efficiency losses, but wouldn't these be offset be easing of the structural/drag issues?


cheers,
Robin.
 
I would imagine that there would be some structural issues there. You would have to run the blade structure around the engine, I dont think blades would take kindly to having their loading structure interupted. Maintenance wise, people who operate helicopters tend to be able to do engine maintenance themselves but as soon as it comes to blade stuff they ship out to experts/manufacturers (think balancing etc.). Putting a turbine at a mid point (or even end point for that matter) of the blade opens a whole can of maintenance issue worms (IMO).
 
AeroFranz said:
The ill-fated efforts with DARPA's heliplane (http://www.darpa.mil/TTO/Programs/h...tipjets on the DARPA Heliplane was the noise.
Click to expand...
 
From the text of the cited document: "In a pneumatically driven helicopter, power is transmitted as heated, compressed gas through lightweight ducting. In a shaft-drive helicopter, a transmission gearbox converts the engine power that is input at high rpm/low torque and delivers it to the main rotor at low rpm/high torque. As the helicopter gets bigger the size, weight, and cost of the transmission increase at a much higher rate than the helicopter size, and soon become limiting factors."

The largest useful rotorcraft gearbox to date (to my knowledge) belongs to the Mi-26. It can pick up 20 ton payloads, in appropriate atmospheric conditions, and move it short distances while significantly reducing the TBO on the main gear box. I think that the infrastructure needed to maintain a conventional helicopter able to lift sixty tons would have been, and like still would, cause leaders to think hard about the cost/benefit analysis.

On the VHLH, I suspect that the higher weights would have made the rotor blade retention mechanics a bit more challenging, given the moment of the external load is so close to the axis of rotation. The weight of the aircraft would have grown I think pretty substantially had they actually started the program. That said it would still have weighted less than a conventional rotorcraft attempt I think.
 
At first sight this implies that a multi-rotor multi-gearbox skycrane would be lighter than a single-rotor one.
On one hand you have slightly increased weights because you are duplicating all of the rotor systems, which albeit smaller, are still going to weigh more than a single larger one as a sum. On the other hand smaller gearboxes handling the same total horsepower are likely to weigh less (?).
The example of the Mi-26 tells us that the breakeven point is somewhere above that helicopter's lift capacity.
 
Here's the paper I was thinking of.
 

Attachments

  • AIAA - 1992 - 4279 - Reaction Drive Rotors - Lessons Learned.pdf
    860.6 KB · Views: 96
Very good overview of the problem - although the author might be (understandably) a little bit biased and downplays the technical hurdles.
Thanks for sharing!
It is my understanding that the Heliplane had to resort to tip burning because the two FJ44 could not provide enough bleed mass flow to generate the required torque for hover. Silencing is going to be a tough nut to crack as noise varies with the 5th power of exhaust velocity (!)
 
hesham said:
Hi,

in the late of 70s,Hughes developed the VHLH very-heavy-lift helicopter,
This helicopter, having a gross weight of about 270,0001b powered by four low-bypass-
ratio Pratt & Whitney F-100 or G.E. F-101 engines, was designed to carry the 60-ton
XM-1 Main Battle tank for a distance of 100 nautical miles in a ship-to-shore assault mission.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008694_1993008694.pdf
Click to expand...

Is this based on the XH-28?
 
AeroFranz said:
Very good overview of the problem - although the author might be (understandably) a little bit biased and downplays the technical hurdles.
Thanks for sharing!
It is my understanding that the Heliplane had to resort to tip burning because the two FJ44 could not provide enough bleed mass flow to generate the required torque for hover. Silencing is going to be a tough nut to crack as noise varies with the 5th power of exhaust velocity (!)
Click to expand...

Tip jet burning was planned from the get go as it used "cold" bypass air rather than "hot" exhaust air. And according to released info noise was indeed the killer. Now if they didn't need to hover they could have gone without the tipjets and used bypass air to spin up the rotor for a very short rolling takeoff.
 
If they are only spinning it up for takeoff surely it could be done with a clutch system a la most gyrocopters? Would that not be even simpler?
 
I think that the mission was going to be deep CSAR, where the greater speed and range of the autogiro would have helped. Unfortunately hover is pretty much required in that kind of mission :(
 
Abraham Gubler said:
sferrin said:
The problem with sticking turbine engines out at the tips is the weight out at the blade tip (causing the blade to have to be strong), drag, and trying to operate those turbines in a high G field. Not impossible but certainly down the list of possiblities a ways.
Click to expand...

Yet these issues pale into insignificance compared to the complexity of building high powered gear boxes and ducting for hot gas to a rotor tip.
Click to expand...

Not so sure about that. On the Heliplane they didn't even want to deal with electric or hydraulic motors for flap actuation out there let alone something as complex as a turbine engine. Any such engine would likely have to be specifically designed for the application from the get go.
 
At the risk of dismay...

Uh, unless you have superb 'active noise cancellation', hot or cold tip-jets are going to smear across audio spectrum.
http://en.wikipedia.org/wiki/Leslie_speaker
IIRC, the prototype UK Rotodyne also struggled with resonance in the hollow rotors...

And you really, really don't want to hang much on the end of those monster rotors, unless you want to add auxiliary landing gear, too...

Okay, IIRC, recent amateur work on valveless pulse-jets has developed '= =' 'thrust augmentors' that both increase efficiency and suppress noise. But, their duct is again too big, too heavy to hang out at the end of that enormous rotor...

whimsy:
Uh, what if you split the difference ?
Low-powered, light, almost 'auxiliary' tip-jets on two long rotor blades. Powerful jets on two short rotor blades. Passive fat hub...

Two turnin', two burnin' ??
/whimsy

Yeah, right, not nearly crazy enough...
;D
 
Hi,

I think this helicopter was called Hughes Model-1000,that is because
it was appeared in 1980,and also the Model-2000 appeared in early
1980s.
 

Attachments

  • VHLHconcepts.JPG
    VHLHconcepts.JPG
    57.4 KB · Views: 855
  • VHLHTable.JPG
    VHLHTable.JPG
    64.1 KB · Views: 775
Triton said:
sferrin said:
Those top two look familiar. ;)
Click to expand...

Really? I haven't seen a shaft drive single rotor concept from Sikorsky or Lockheed with a 60 ton payload.
Click to expand...

Top one is on here somewhere (saw it just a few weeks ago - Hughes). The middle one is a big Sikorsky beast. I'll scrounge them up later in the week if someone hasn't beat me to it by then.
 
And the design of the third one definitely has "Boeing Vertol" written all over it, don't you think?!
 
sferrin said:
The problem with sticking turbine engines out at the tips is the weight out at the blade tip (causing the blade to have to be strong), drag, and trying to operate those turbines in a high G field. Not impossible but certainly down the list of possiblities a ways.
Click to expand...

Surely the opposite is true; distributing the weight to both ends of the blade lessens the load in the same way as distributing engines and fuel across a conventional wing does (the blade doesn't hang of the chopper - the chopper hangs off the blade).

And applying the torque at the furthest point from the pivot eliminates leverage and further reduces the blade strength required.

As far as G-forces are concerned, this may have some effect on the turbine's bearings but at least the fuel supply would be centrifugally boosted as long as you could get it up through the hub. :)

Cheers, Woody
 
Woody said:
sferrin said:
The problem with sticking turbine engines out at the tips is the weight out at the blade tip (causing the blade to have to be strong), drag, and trying to operate those turbines in a high G field. Not impossible but certainly down the list of possiblities a ways.
Click to expand...

Surely the opposite is true; distributing the weight to both ends of the blade lessens the load in the same way as distributing engines and fuel across a conventional wing does (the blade doesn't hang of the chopper - the chopper hangs off the blade).
Click to expand...

Centrifugal force.

Woody said:
As far as G-forces are concerned, this may have some effect on the turbine's bearings but at least the fuel supply would be centrifugally boosted as long as you could get it up through the hub. :)

Cheers, Woody
Click to expand...

In a situation like that even the AIR in the rotor blade gets thrown outboard making it a pump. As for turbines, at least on the DARPA Heliplane, nobody wanted anything to do with them out at the tips. Nobody even wanted to mount actuators of any kind out there. Too much weight and too many problems operating in a high G field.
 
There is no information in the report to suggest that the shaft drive single rotor or shaft drive tandem rotor design concepts are from any other manufacturer than Hughes Helicopters, Inc. I haven't seen any design concepts from Sikorsky, Lockheed, or Boeing-Vertol capable of lifting 60-ton payloads.
 
SaturnCanuck said:
sferrin said:
Centrifugal force.
Click to expand...

Sorry, no such thing.

Its inertia.
Click to expand...

Call it what you want. ::) You'll want to go straighten these guys out too:

http://www.dynamicflight.com/aerodynamics/centrifugal_force/
 
Triton said:
There is no information in the report to suggest that the shaft drive single rotor or shaft drive tandem rotor design concepts are from any other manufacturer than Hughes Helicopters, Inc. I haven't seen any design concepts from Sikorsky, Lockheed, or Boeing-Vertol capable of lifting 60-ton payloads.
Click to expand...

Well it seems fate is conspiring against me. After seeing the thing dozens of times looking for other things I can't find the godd--n thing. I swear I got it off of Scott's blog but a search there gets me squat. It's the Sikorsky HLH and there's a color picture of it carrying something like a Minuteman or Titan (yes Titan) missile or some such. 160'+ rotor diameter. I'll check at work tomorrow. As for other companies designs there are some right on this site if you look. (scrounged from another thread)
 

Attachments

  • Sikorsky HLH.jpg
    Sikorsky HLH.jpg
    244.7 KB · Views: 1,079
sferrrin, you might be thinking of the Sikorsky DS-103 discussed in this topic:

http://www.secretprojects.co.uk/forum/index.php/topic,1051.msg8380.html#msg8380

index.php


The shaft drive single rotor VHLH helicopter concept is larger than the Sikorsky DS-103. Rotor diameter of the VHLH is 246 ft compared to the 160 ft rotor diameter of the DS-103. The VHLH has a payload of 60 tons compared to the 40 ton payload of the Sikorsky DS-103.
 
Yeah that was the one I was thinking of. Big as it is it's still got quite a ways to go to match the one in that paper I guess. :-\
 
Re: Lockheed HLH heavy-lift helicopter project......

Triton said:
sferrin said:
Those top two look familiar. ;)
Click to expand...

Really? I haven't seen a shaft drive single rotor concept from Sikorsky or Lockheed with a 60 ton payload.
Click to expand...

Dear Triton here is a picture with a caption in French that I've found of a Lockheed HLH "project" using (I think) Lockheed's rigid-rotor. I couldn't find a topic on Lockheed HLH "projects" elsewhere, so I've put it here......

The picture comes from the 15th December 1966 issue of Aviation Magazine International......

Terry (Caravellarella)
 

Similar threads

Please donate to support the forum.

Back
Top Bottom