Very light combat helicopter projects?

[cluttonfred]

I am always fascinated by doing more with less rather than the other way around. As modern "smart" weapons get ever smarter, smaller and lighter (partly to cater for growing UAV/UCAV needs) it also means that very light aircraft can potentially be more useful than ever.

There have been lots of militarized and/or armed light aircraft over the years -- the MFI/Saab Supporter series and it's Pakistan-produced derivatives, for example -- but I have always wondered why there are no combat versions of very light helicopters like the Robinson R22 and Schweizer 300 series. The little French Djinn cold-jet helicopter could carry anti-tank missiles, too, IIRC.

Obviously, the payload of such helicopters is very small. But even something as small as a ruggedized, single-seat derivative of the tiny Robinson R22 could be useful in some circumstances, hugging the terrain to pop up and spray with a light machine gun and lob of salvo of RPGs, for example.

So, does anyone know of any projects for armed variants or derivatives of very light helicopters, or similar original designs? I am thinking mostly of piston-engined, 2-3 seat light helicopters or their equivalents, though anything in the same spirit would be interesting.

Cheers,

Matthew

 

[hole in the ground]

http://www.aviastar.org/helicopters_eng/mcdonnel_120.php

this helicopter has always fascinated me. Another cold cycle helicopter. Very compact design. Payload was podded and interchangeable, could carry a troop pod with 12 troops. Dont think it was tested with weapons though.

 

[cluttonfred]

I have always liked that one, too, and the cold-jet helicopter principle in general. Here's a pic of one that appears to be armed, though the Model 120 is a lot bigger than what I had in mind for this thread.

The Sud-Ouest Djinn <http://en.wikipedia.org/wiki/Sud-Ouest_Djinn> that I mentioned earlier was evaluated by the U.S. Army in the 50s and was well-liked for its simplicity (no rotor torque, no transmission, directional control by a simple rudder placed in the engine exhaust) but IIRC there was too much political opposition to buying a foreign design. Here's a pic of one with a pair of Nord SS.10 wire-guided, manually-steered anti-tank missiles mounted.

It's not to hard to imagine a modern, single-seat version with a rocket pod or a couple of fire-and-forget missiles and a machine gun or automatic grenade launcher.

 

[amsci99]

Thanks for the posts and I'm very interested to find out more about the MD Model 120,especially the technical bits. I do have some information on the Djinn's rotor assembly.

 

[LowObservable]

Model 120, Djinn? Porkers. See:

http://www.aviastar.org/helicopters_eng/hiller_yh-32a.php

 

[cluttonfred]

Now we're talking!

Still, without a windshield I'd be a bit worried about the backblast from those missiles in the photo in the link. And powered tip jets are said to be truly, painfully, horrifyingly loud. Makes it harder to sneak up on the bad guys.

More, more...! ;D

 

[Just call me Ray]

What the heck is that big old black thing in the background?

 

[flateric]

Boeing Condor HALE UAV
http://www.vectorsite.net/twuav_12.html#m4
http://www.spyflight.co.uk/boeing%20condor.htm

 

[frank]

Would the Bell Sioux Scout fit the bill?

 

[Orionblamblam]

VolJet combat chopper designs from the 70's (before the Shaw of Iran was deposed). Artwork done by Jim Bryant.

Promo videos:
http://video.google.com/videoplay?docid=2843781459285030350

http://www.youtube.com/watch?v=lDOuoG6ljZA

 

[yasotay]

The OH-6 Loach was about as close as you are going to come to the concept in the US. Challenge has been that once you start adding "stuff" to make it work (radios, IFF, armor to important areas, etc.) you start needing a bigger engine, then you need a bigger transmission then you need more gas and on and so forth. Another issue is that smaller aircraft are more vulnerable to small arms fire (less volume = higher probability of something important getting hit). Then there is the whole pilot workload thing (recall the Russians have apparently elected to go to a two seat Ka-52 vice Ka-50). Lots more accidents are possible because you don't have a second set of eyes to keep looking out while one changes radio frequencies or tinkers with some knob. With all of that it comes off not being as economical as one might think. Plus there is the maintenance requirement. May have gobs of helicopters and pilots, but you still need a number of crew chiefs to keep them working while the aviators are regaling themselves at the club. ;D

 

[cluttonfred]

Would the Bell Sioux Scout fit the bill?

That's a little bigger and heavier than I had in mind.

Actually, I spoke too soon. The Bell Model 207 Sioux Scout, a tandem-cockpit version of the ubiquitous Bell Model 47/OH-13, is exactly what I had in mind. Bell intended it as a proof-of-concept for the idea behind the Huey Cobra, but a modern version would be perfect. Updated materials and components should be able to shave some weight off the airframe. That and making it a single seater ought to allow for 100 lb of armor and maybe 250 lb of weapons--not much, but enough for, say, a single machine gun and a pair of Hellfires OR seven 70mm rockets. Since several manufacturersa re working on 70mm-compatible guided weapons, that's seven little laser-guided weapons and an MG to keep the bad guys' heads down.

 

[cluttonfred]

The OH-6 Loach was about as close as you are going to come to the concept in the US. Challenge has been that once you start adding "stuff" to make it work (radios, IFF, armor to important areas, etc.) you start needing a bigger engine, then you need a bigger transmission then you need more gas and on and so forth. Another issue is that smaller aircraft are more vulnerable to small arms fire (less volume = higher probability of something important getting hit). Then there is the whole pilot workload thing (recall the Russians have apparently elected to go to a two seat Ka-52 vice Ka-50). Lots more accidents are possible because you don't have a second set of eyes to keep looking out while one changes radio frequencies or tinkers with some knob. With all of that it comes off not being as economical as one might think. Plus there is the maintenance requirement. May have gobs of helicopters and pilots, but you still need a number of crew chiefs to keep them working while the aviators are regaling themselves at the club. ;D

I agree with you up to a point. If you try to cram big-aircraft systems into a small airframe, the you will absolutely have the weight creep up and the performance go down as you describle. If you ask a solo pilot to do the work of a pilot and gunner, then you are asking for trouble. And yes, the maintenance requirement is always there. But the fixed-wing world has seen several examples of returns to simplicity -- usually driven by just one dedicated designer's convictions. Ed Heinemann's Douglas A-4 Skyhawk and Teddy Petter's Folland Gnat are the two that come to mind. Modern glass cockpits and things like voice-controlled systems can help a pilot process the needed information safely if, and it's a very inportant "if," things are kept simple.

I do not agree on the "less volume = higher probability of something important getting hit" argument. That might be true in terms of critical systems hit vs. number of hits, but it leaves out the fact that most of the rounds that hit the big airframe miss the small airframe altogether. If the volumes of the critical areas are the same (pilots don't get any smaller) or less (engines, etc. do get proportionally smaller) then the smaller airframe is less vulnerable per shot fired.

The incentives for aircraft builders to make aircraft bigger (like cars, the profit margin often goes up with size and complexity) and the vaguaries of government procurement and legislative committees making it easier to fund one humongous program than several smaller programs. We end up with a limited number of very capable aircraft, but sometimes it would be nice for the troops in the field to have an imperfect solution right now vs. a perfect solution when the assets are available.

I dare say that something like a Robinson R44 four-seat piston-engine helicopter could be a great asset to troops in the field. It could even ride in an armored container on a truck and be deployed with the troops. Strip it down to a "dune buggy" simple single-seater and you might have 600 lbs available. Use 150 lbs for armor and add a light machine gun and you can still put a .50 cal machine gun pod OR two Hellfires OR seven 70mm rockets on EACH of two hard points. That's not bad, and it's way better than a sharp stick, as the saying goes.

 

[cluttonfred]

Thanks very much for the info on the VOLJET helicopter and the great video. I want one! (You may want to delete the second video as it is included in the first one.)

Does anyone know of any technical papers or other sources which might quantify the pros and cons of pressure jet helicopters vs. more conventional ones? I did a couple of searches on the NASA Technical Report Server but no luck.

For more fun with little cold jet helicopters, here's a nice video clip of the tiny Dornier Do.32, which was also developed into the Do.34 unmanned, tethered aerial observation platform.

http://www.dailymotion.com/video/x7z3f8_flying-half-pint-helicopter_tech

 

[LowObservable]

<I'd be a bit worried about the backblast from those missiles>

I'd be more worried about the 85 mm backblast from whatever I'd just missed.

 

[Jemiba]

Mention of the Do 12 brought memories back to my mind, that I've
seen pictures of another cold tipjet type and it's possible armed
derivatives, the VFW H3 Sprinter.
It's a pity, that all versions were just shown in top views in FlugRevue 5/1969 : :-\

 

[Matej]

This can also fit to the topic:

http://www.secretprojects.co.uk/forum/index.php/topic,421.0/highlight,czech+helicopters.html

 

[Wembley]

There was a two-man micro-VTOL craft caled Phalanx Dragon in the 80's that never got off the ground, IIRC - very futuristic, anyone got any pics?

 

[Matej]

Forum search engine is your friend

http://www.secretprojects.co.uk/forum/index.php/topic,234.0/highlight,phalanx.html

But its not a helicopter.

 

[Wembley]

...thanks - just found it myself. Not a helicopter, but very much in the spirit of the thread I hope (even if the idea was crazy).

 

[Michel Van]

The Little Nellie autogyro with its creator and pilot, Ken Wallis.

sorry for putting a 007 Movie prop here, but they build it and it flown
in Movie armed with mashinegun, rocketlauncher, Flametrower and minibombs
See it as Protoype of a interesting concept that really works it had been used !

http://www.youtube.com/watch?v=IOSiDF612Wk
The Little Nellie glory

smaller and we are in UCA Bussines of Model helicopter

wat was alrady used by japanes Yakuza in 1970's
were someone used a Model helicopter with expolsive, to blow up a Competitors
source: a TV doku about Yakuza i saw year ago.

 

[Rickshaw]

VolJet combat chopper designs from the 70's (before the Shaw of Iran was deposed).

I think you mean the Shah of Iran. Unless there was someone called "Shaw" who lived in Iran? :

 

[Rickshaw]

Mention of the Do 12 brought memories back to my mind, that I've
seen pictures of another cold tipjet type and it's possible armed
derivatives, the VFW H3 Sprinter.
It's a pity, that all versions were just shown in top views in FlugRevue 5/1969 : :-\

See: http://www.aviastar.org/helicopters_eng/vfw_h-3.php for development history of the VFW H3.

 

[Jemiba]

Another helicopter, that would probably fits to the heading of this thread,
is the argentine CH-14, see http://www.rotaryforum.com/forum/showthread.php?t=14959.

(photo from Aviation News February 2008)

 

[Matej]

I am curious if the faceted fuselage has some real purpose or is it just for a "cool looking" vehicle? I think that from the manufacturing point of view, there is not any real difference compared to curves.

 

[amsci99]

Now this is a strange one called the Intora Firebird, I first read about it in the 90s in Air International magazine and wondered how much range would a hydrogen peroxide powered rotorcraft offer, not discounting the cost and hazards associated with that compound.The official website has been down for sometime.

http://www.youtube.com/watch?v=O9S_Qmn-CEM

http://www.flightglobal.com/articles/1998/09/08/41959/unorthodox-fuel-puts-firebird-in-class-of-its-own.html

 

[cluttonfred]

Oh dear, hydrogen peroxide.... The video's background music hides the evidence, but I bet that the Firebird was earsplittingly noisy like most hot jet rotor designs. That and the prospects of what happens if a stray bullet punctures those fuel tanks on either side of the pilot. No, thank you.

On a different note, the talk of cold jet helicopters earlier in this thread has me dreaming of a cold jet ultralight helicopter. Does anyone know of a cold jet helicopter, real or a paper design, that powered the compressor with a piston engine? I would think that a two-stroke would have the power-to-weight ratio to make it work.

 

[robunos]

...the Intora Firebird...

looks a lot like the Hiller/Saro XROE-1 rotorcycle...

cheers,
Robin.

 

[Apophenia]

The Argentinian CH-14 made me think of Cardoen's proposed single-seat Jet Ranger derivative.

 

[fightingirish]

The Argentinian CH-14 made me think of Cardoen's proposed single-seat Jet Ranger derivative.

That picture larger.
More info about the Cardoen at Aviastar.
Link: http://www.aviastar.org/helicopters_eng/cardoen.php

Picture source: http://sobchak.wordpress.com/2008/08/

If this picture has been posted be before or violates copyright and forum rules , please let me know via PM and I will delete this post.

 

[ouroboros]

The VolJet prototype is very interesting. I assume the fundamental problem of all cold jet rotor systems is the fuel efficiency/weight of the compressor? As a slightly left field option, the guys at RamGen designed a supersonic compressor/engine that may have desirable characteristics for this application.

I suppose also that the option of going cold in the rotor and using a tip jet combustor is not being reconsidered for some reason? I understand the Rotodyne was loud but that good progress was being made on noise reduction though. Considering modern design capabilities, I would have figured there might have been some resurgence in interest.

As far as pressure systems are concerned, is the primary advantage of tip jet systems the larger rotor, compared to a rim driven ducted rotor?

Were there any systems that bled some air from the rotor blade interior out the trailing edge, conceptually similar to blown flaps or distributed propulsion/lift systems?

 

[Mark Nankivil]

Greetings All -

I recently found in our museum archives a flight manual and maintenance handbook/parts listing for the Hiller HOE-1/YH-32. Here's some of the drawings from the manual & handbook. Can't say I remember seeing other ramjet tipped rotorcraft also having a tail rotor. I know none of McDonnell's rotorcraft had a tail rotor but can see where Hiller's inclusion of a tail rotor would improve manueverability.

Enjoy the Day! Mark

 

[CostasTT]

The Argentinian CH-14 made me think of Cardoen's proposed single-seat Jet Ranger derivative.

That picture larger.
More info about the Cardoen at Aviastar.
Link: http://www.aviastar.org/helicopters_eng/cardoen.php

Picture source: http://sobchak.wordpress.com/2008/08/

If this picture has been posted be before or violates copyright and forum rules , please let me know via PM and I will delete this post.

This appears to be the Cardoen Bo 105 derivative, which was built at least as a mock-up.
Pictures and info on both it and the Long Ranger derivative: http://chileanhelicopter.blogspot.com

 

[Apophenia]

This appears to be the Cardoen Bo 105 derivative, which was built at least as a mock-up.
Pictures and info on both it and the Long Ranger derivative: http://chileanhelicopter.blogspot.com

Quite right. Thanks for the correction Costas!

 

[Madurai]

Would the mid-Eighties IAR Airfox be small enough to qualify?

 

[CostasTT]

This appears to be the Cardoen Bo 105 derivative, which was built at least as a mock-up.
Pictures and info on both it and the Long Ranger derivative: http://chileanhelicopter.blogspot.com

Quite right. Thanks for the correction Costas!

You're welcome.

 

[Boxman]

Silent footage from the San Diego Air & Space Museum (SDASM) posted today (23-September-2014) on YouTube of the Dornier 32 apparently on a promotional trip to Washington, D.C. Apparently Ryan was Dornier's partner in promoting the aircraft here in the United States. Aside from flight footage, there is also some interesting footage beginning at approximately the 10 min 15 sec mark of the aircraft being disassembled and stowed back into its trailer.
http://www.youtube.com/watch?v=RWNBp-8mIRY

 

[hesham]

Hi,


a clear view to Cadroen helicopter full size mock-up.

 

[Motocar]

Intora Firebird Helicopter...!

 

[Pirate Pete]

Seeing the picture of 'Little Nellie' reminded me that I had this buried in my 'archive'
(From an old edition, 1967 I think, of the Observers book of Aircraft, sadly no longer in my possession).