Alternate UTTAS designs from Bell, Sikorsky and Boeing

uk 75

uk 75

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Apart from the winning Sikorsky and the runner-up Boeing design in the 70s for the US UTTAS requirement which produced the in-service Blackhawk, I gather Bell and other US firms came up with designs. I am sorry if this info is in one of the existing threads..
The Boeing design was really nice and looks like an early drawing of the Westland WG34 (precursor to the Merlin).

UK 75
 
I figure whatever Bell's big variant of the Huey is would have been their entry. And technically, Blackhawk is the S-67/AH-3. The UH-60 is Black Hawk.
 
At least at an early stage, Sikorsky entered the race with another UTTAS concept,
with an co-axial rigid rotor (think, I've posted this picture before, but couldn't find it now ..)
(from Aviation Week January 1968)
 

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Bells - UTTAS design
 

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I remember talking to one of the (now retired) Sikorsky designers at a Symposium almost ten years ago. They had been very excited at the possibilities of the ABC (counter-rotating) rotor system in the 60s, 70s and 80s with what it might bring to helicopters. They had some technical issues, that I do not recall, and they felt a lot of resistance to the unfamiliar design/concept by their customer. What I remember most of our discussion was his frustration at the US Army's technical conservatism.

I think Bell lost out early because they stuck with the teetering hinge rotor system; betting that the Army would stay with 'tried and true' systems. I cannot say for certain but I think you would find that it was right after their early lose in the UTTAS competition that Bell began work on a different four bladed rotor system. One that would eventually be put on the 412. (note: Jazz posted the picture as I was writing this. I note that it shows what appears to be an in-plane four bladed rotor system. I thought originally Bell had gone with the two bladed system, but then recalled I was thinking of the YAH-63.)

Ultimately I must say I am satisfied with the results of the competition as I spent the better part of my career flying around in the UTTAS winner. It seems to have held up rather well to the requirements it was developed for.
 
From what I've heard, Bell stayed with the two-bladed teetering rotor system for so long because someone fairly high up owned th e patent on the system. When this party retired, they could move forward with new concepts in rotor design.
 
elmayerle said:
From what I've heard, Bell stayed with the two-bladed teetering rotor system for so long because someone fairly high up owned th e patent on the system. When this party retired, they could move forward with new concepts in rotor design.
Click to expand...

Hmm...funny that's exactly the same situation we had with Sukhoi C-37 Berkut and comrade Simonov...
 
elmayerle said:
From what I've heard, Bell stayed with the two-bladed teetering rotor system for so long because someone fairly high up owned th e patent on the system. When this party retired, they could move forward with new concepts in rotor design.
Click to expand...


That is not surprising, now that you mention it. Larry Bell, made his company on the teetering hinge rotor system. Keeping in mind how the OH-58A became the Army's scout helicopter, reliance on patronage seems to have been very real for them.
 
I like it! It makes me wish they had gone with that instead of the YUH-61.

"Science vs. Norse Mythology" is pretty cool, too.
 
Pictures of the Bell 240 proposal are extremely hard to find. Here is a two-page period advertisement currently for sale on eBay. I have restored the picture (small size, unfortunately) for presentation here.
 

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Stargazer2006 said:
Pictures of the Bell 240 proposal are extremely hard to find.
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Maybe this will help. This is the Bell factory proposal model for the Bell 240. It came with both main rotors (2-blade and 4-blade). Unfortunately, the tail rotor and its "football" gear box fairing are missing and have not (yet) been replaced. The main landing gear can sit down to a low position for loading convenience.

I believe this is the same model used in all Bell photography, such as in replies 4 and 11 in this thread.
 

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The auction ended with zero bid?!? At only $175 for such an interesting piece? Strange enough.
 
Differences between the Sikorsky YUH-60 and Sikorsky UH-60A.

Source:
http://www.sikorskyarchives.com/S-70%20%28YUH-60A%20UTTAS%29.PHP
 

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Artist's impression of Sikorsky Advancing Blade Concept (ABC) UTTAS concept.

Source:
http://www.sikorskyarchives.com/S-69%20%28XH-59A%29.php
 

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I've always liked the compactness appearance of the Sikorsky Advancing Blade Concept (ABC) UTTAS concept! Although I'm not sure how the stacked main rotor system would have went in the air-portability requirement! But then again Sikorsky would not have designed such a helicopter without this requirement being adhered too!
Would I be correct in assuming (as with the Kamov Ka-25 & Ka-27 series) that minus its long tail boom and tail rotor system it could be somewhat of a safer design (less likelihood of tail boom and rotor strikes in both peace and combat????


Thanks for sharing!!

Regards
Pioneer
 
YUH-60 was originally designed with a very short main rotor mast. The short rotor mast helped when stuffing it into a C-5A for over seas deployments. After they encountered problems with "shaving" the transmission fairing, they installed a taller rotor mast.
 
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An interesting note that all the early Sikorsky designs of ABC had the rotor/transmission over the cabin. All of the recent aircraft have the dynamics behind the cabin.
 
Stumbled across this document today, "The Decision to Develop the UTTAS":

http://www.dtic.mil/get-tr-doc/pdf?AD=AD0765438

This was new to me:
Vought Helicopters was formed to be the sole licensee in the
United States for L'Industrie Aero Nautique et Spatiale Francaise.

Their UTTAS candidate, the SA 330, had been jointly developed by the
French and British.

Vought would manufacture the SA 330 in Dallas, should it prove to be
one of the two airframe finalists.
Click to expand...

US Army Pumas... I can dream :)

Digging into DTIC a bit more with those search terms reveals that Vought were very interested in the Fenestron and its possible application to the Puma:

The objective was to design and evaluate a ducted fan-in-fin system for a helicopter in the 14,000- to 15,000-lb gross weight and 150-kt to 160-kt speed class. ... From the knowledge gained, a ducted fan-in-fin antitorque device was designed for the utility transport helicopter in the specified weight and speed class of the SA 330.
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http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0747806

I wonder what was the relationship of that design and the Fenestron for the SA330Z?

In 1973 Aérospatiale bought-out Vought Helicopters and they became solely a distributor within the USA. It became Aérospatiale Helicopter Corporation and then many years later became American Eurocopter; so "Vought" finally won a US Army contract with the UH-72!
 
Fantastic find, Kiltonge! Thanks a lot for this.

I knew that Vought had a connection with Aerospatiale but wasn't aware either of the prospect of a UTTAS Puma (which would have been even more interesting with a Fenestron!!)
 
hesham said:
Nice find Kiltonge.
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I second this!

I find it interesting how air-transportable Aerospatiale and Vought could have modified the Puma design to be!
After all its over-all height would have made it a somewhat difficult helicopter to carry. I've seen a picture of an RAF Puma being loaded/unloaded from a Short Belfast, which appears to have substantially striped-down (minus rotor and transmission, if my memory serves me right!) to fit within its fuselage. I don't even think the Puma had a folding / storable main rotor did it?

Regards
Pioneer
 
On the French machines at least, it can.
 

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dan_inbox said:
On the French machines at least, it can.
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Yeah thanks dan_inbox.
I completely overlooked the Naval ship-compatible variant of the Puma. Although I think this derivative came long after the UTTAS competition.
Although saying this, your photo specifically emphasises the hight of the Puma I'm explicitly concerned about!

Regards
Pioneer
 
Pioneer said:
I find it interesting how air-transportable Aerospatiale and Vought could have modified the Puma design to be!
Click to expand...

You're spot on :)

Aerospatiale claims that Puma meets all the requirements of the US Uttas military helicopter specification
except the height limitation for air transportability without dismantling.
Click to expand...

https://www.flightglobal.com/FlightPDFArchive/1973/1973%20-%202845.PDF

Of course the solution to that was exacly what Sikorsky eventually did, discard the height requirement in order to eliminate the vibration and blade-strike problems. They won despite no longer fitting in a C-130 and Boeing, desperately trying to find a solution whilst adhering to the requirements, lost.


Another strange UTTAS twist I've just discovered is that Lycoming took their losing engine candidate, the T405 or PLT27, and modified it to become the AGT-1500 which went on to power nearly 10,000 M1 tanks.

Total production of the GE T700 is currently around 16,000 whereas the AGT-1500 had reached 13,000 units back in 1996!
 
Very interesting points you make Kiltonge!

Regards
Pioneer
 
From Sikorsky Archive,

the early conceptS which led to UTTAS.
 

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Please help,

I can't understand this,was it alternative fuselage configurations to UH-60 or what ?.

https://apps.dtic.mil/dtic/tr/fulltext/u2/a058906.pdf
 

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hesham said:
Please help,

I can't understand this,was it alternative fuselage configurations to UH-60 or what ?.
Click to expand...
https://www.secretprojects.co.uk/forum/index.php/topic,12597.msg161428.html#msg161428
http://up-ship.com/blog/?p=9714
 
riggerrob said:
YUH-60 was originally designed with a very short main rotor mast. The short rotor mast helped when surfing into a C-5A for over seas deployments. After they encountered problems with "shaving" the transmission fairing, they installed a taller rotor mast.
Click to expand...
I'm under the impression that RfP was for the UTTAS was for the design to fit into both the Lockheed C-130 and C-141, as opposed to the later and larger C-5.

Regards
Pioneer
 

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Pioneer said:
riggerrob said:
YUH-60 was originally designed with a very short main rotor mast. The short rotor mast helped when surfing into a C-5A for over seas deployments. After they encountered problems with "shaving" the transmission fairing, they installed a taller rotor mast.
Click to expand...
I'm under the impression that RfP was for the UTTAS was for the design to fit into both the Lockheed C-130 and C-141, as opposed to the later and larger C-5.

Regards
Pioneer
Click to expand...
Just found this under UTTAS RfP

"Air transportability within a C-130 airframe
(it being the smallest airlifter in the
USAF trinity of C-5, C-141 and C-130 at the
time). Stringent limits were also placed on
teardown times, loading times and rebuild
times. The single biggest factor was the
reduced height of the C130 cabin, around
9ft, and the relatively short length between
the cockpit bulkhead and the ramp hinge –
which necessitated the tail to be foldable"

Regards
Pioneer
 
Pioneer said:
riggerrob said:
YUH-60 was originally designed with a very short main rotor mast. The short rotor mast helped when surfing into a C-5A for over seas deployments. After they encountered problems with "shaving" the transmission fairing, they installed a taller rotor mast.
Click to expand...
I'm under the impression that RfP was for the UTTAS was for the design to fit into both the Lockheed C-130 and C-141, as opposed to the later and larger C-5.

Regards
Pioneer
Click to expand...

Some where out there, there must be a similar picture of the Boeing Vertol YUH-61A in a similar folded configuration for air transport

Regards
Pioneer
 
Pioneer said:
riggerrob said:
YUH-60 was originally designed with a very short main rotor mast. The short rotor mast helped when surfing into a C-5A for over seas deployments. After they encountered problems with "shaving" the transmission fairing, they installed a taller rotor mast.
Click to expand...
I'm under the impression that RfP was for the UTTAS was for the design to fit into both the Lockheed C-130 and C-141, as opposed to the later and larger C-5.

Regards
Pioneer
Click to expand...
Pioneer said:
riggerrob said:
YUH-60 was originally designed with a very short main rotor mast. The short rotor mast helped when surfing into a C-5A for over seas deployments. After they encountered problems with "shaving" the transmission fairing, they installed a taller rotor mast.
Click to expand...
I'm under the impression that RfP was for the UTTAS was for the design to fit into both the Lockheed C-130 and C-141, as opposed to the later and larger C-5.

Regards
Pioneer
Click to expand...
Ok, as a follow on to the above, this video indicates that 1 x UTTAS was expected to fit within a Lockheed C-130, 2 x UTTAS in a Lockheed C-141 and 6 x UTTAS in a Lockheed C-5.
I'd be interested know when the specification for the UTTAS to be carried by both C-130 and C-141 was dropped as a requirement.

View: https://youtu.be/FdlweZ-3b9M


Regards
Pioneer
 
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Total speculation on my part. C-130 requirement may have been dismissed after the rotor system had to be heightened due to blade flapping on both (?) competing helicopters. With the increase in height of the rotor head, it may have not been feasible any more for them to be put into the C-130. The C-141 requirement may have gone away due to weight restrictions on the C-141 later in life and their impending retirement.
 

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