Bell Model 204 / XH-40 / UH-1 Iroquois competitors, projects and modifications

In 1955, the US Army issued a requirement for the development of a next generation gas turbine-powered medivac helicopter
The winner of this competition would be awarded to Bell with their Model 204, then designated as the XH-40, and later again in 1962 it was changed to UH-1 Iroquois.

I have read somewhere that over 20 companies responded to the US Army’s Request for Proposal.

What were the other designs that were submitted to this competition that would lead to over 16,000 being produced in various variants?
The companies, photos, drawings, artist impressions and specifications would make for a great forum!

Regards
Pioneer

On april 1969 a Bell UH-1 research compound helicopter established an unofficial world speed record for a rotary wing aircraft in level flight when it flew at 316 mph, accoding to a Textron Bell release. The high performance helicopter was performed under a contract with the U.S. Army Aviation Materiel Laboratories. Tests were being made to investigate rotor characteristics during operation at high advance ratios (0,716), high blade Mach numbers and aircraft maneuvers. The modified YH-40, the fourth aircraft of the UH-1 series, built in 1956, has a Lycoming T53-L-13 as its primary engine and two Pratt and Whitney JT12-A3 engines with 3300 pounds of static thrust each, on its wingtips. The aircraft features and integrated control system which allows conversion from conventional helicopter controls to airplane type controls as air speed increases above cca 150 knots.

Naval News june/69

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A jet powered Huey?!? ...to set world speed record?!?!?

Now I cleared what impressed me so much. Jet engines are at the end of the pylons (maybe photoshoped, or to consider that era - retouched??) Original Bell model 553 had them directly on the fuselage.

I just took a look at vertiflite article that I have from Jemiba and found this four bladed version of model 553. So it is confirmed now.

There is a major confusion here over the designator.
It should read "Bell 533" and NOT "553" as some of these posts state.

Hi All -

A search here and there has yielded me nothing on the identity of this Huey - Baugher's site shows it to be a UH-1C-BF if I have the serial presentation correct. I have little in the way of books on helicopters - guess I need to start filling that gap in my library. Anyone know what's up with this interesting looking Huey?

Thanks to my friend Mike Burke for loaning me this to scan and share.

Thanks! Mark

Mark, that's the Bell 533 High Performance Helicopter (HPH), a modified YH-40-BF fitted with J69s. The photo was taken after the flight trials when its weird, narrow-chord wings were removed.

Thanks - from another friend, the specific info is Bell Model 533 YH-40 56-6723

Never would have guessed a 1956 fiscal year - learn something new every day...

Enjoy the Day! Mark

Mark,

there is an entry about Model 533 at Putnam's Bell Aircraft pg 140. Send me a PM if you need a scan

regards,

Antonio

Here is a series of pics of the Model 533 helicopter.
As for the YH-40 designation, it refered to the six pre-production aircraft of the Iroquois ("Huey") series, later redesignated as YHU-1B (and then YUH-1B). The Model 533 was indeed one of these aircraft but the YH-40 designation does not refer specifically to the jet modification.
On a side note, there were three XH-40 (XHU-1) prototypes before the "Y" batch.

Thanks for the additional photos - interesting to sse the wing and to see a 4 blade rotor too.

Enjoy the Day! Mark

I've got two additional pictures taken later with a different jet installment, as follows. Strangely enough, one of these carries the mention "Model 553", which I think is a typo for "533", as there probably was only one single research program.

*sigh* back when the Army was not afraid to experiment, for experiments sake. One of these is on display at Ft. Eustis, Virginia. It is across the street from the Aviation Applied Technology Directorate.

You bet! Also of interest is the number of rotor blades according to the picture. Sometimes it's 2, sometimes 3, sometimes 4. Also the wings appear on some pics, not others. Obviously the Model 533 was extensively tested in all manners of configurations.

From Aviation Week May, 1969:

Have you got a pic showing the 3 blade rotor?

Stargazer2006 said:

You bet! Also of interest is the number of rotor blades according to the picture. Sometimes it's 2, sometimes 3, sometimes 4. Also the wings appear on some pics, not others. Obviously the Model 533 was extensively tested in all manners of configurations.

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Oops, from the angle of the very first picture, I figured this was a three-blade configuration, but on closer look, this must be the result of a wide-angle lens, because obviously there are only two blades visible. So maybe there NEVER was a three-blade version after all.

Stargazer2006 said:

I've got two additional pictures taken later with a different jet installment, as follows. Strangely enough, one of these carries the mention "Model 553", which I think is a typo for "533", as there probably was only one single research program.

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I checked the article once again - you are right, there is written Model 533, my typo.

From vertiflite, Summer 2006, and, yes, there was a 3-bladed rotor :

"August 7, 1961. Funded under;i U.S. Army 'I'ransportation Research Command (TRECOM) contract
for a high-performance research helicopter, Bell modified a YH-40 helicopter with UH-1B dynamic
components. The company designation was Model 533. The primary objective of the project was to
evaluate various rotor systems and methods of drag reduction. Initial modifications included the
addition of fiberglass honeycomb aerodynamic fairings on the rear fuselage, streamlined fairings for the
landing skids, a cambered vertical fin on the tailboom to unload the tail rotor, and an in-flight tiltable
rotor mast protruding from a large, neatly-faired structure above the cabin. Shortly after the aircraft
achieved its first flight on August 10, 1962 with the standard UH-1B 44 ft two-bladed rotor, another
rotor systerm was tested on the Model 533: a gimbal-mounted 42 ft diameter, three-bladed rotor,
which could be m mounted to the mast either rigidly or through a gimbal. The control system was
modified to accommodate the tilting pylon systemand to be adaptable to both the 2-bladed and
3-bladed rotor system. True level flight airspeeds of 150 knots (173 mph) were achieved with the
standard 2-bladed rotor. Having established the basic benefits of drag reduction, the U.S. Army funded
a second phase with the main purpose of investigating the effects of auxiliary thrust. Bell used two
920 lb thrust Continental J69-T-9 turbojet engines in pods attached closely to each side of the
fuselage for this purpose. The 2-bladed rotor was chosen for this program and the standard UH-1B
blades were replaced with an experimental set. A pair of sweptback wings spanning 26.8 ft was fitted
to the lower fuselage. These wings had groundadjustable sweep and could be tilted in flight. The tilt
mechanism was later coupled to the collective control to avoid excessive wing lift and attendant rotor
rpm control problems during autorotation. After exploratory testing in pure helicopter configuration, the
wings were removed and the turbojet engines were fitted. Flight tests in this configuration began on
21 October 1963. An additional elevator was soon installed on the vertical fin, opposite the tail rotor,
since the standard elevators were now located in an area of turbulent airflow from the jet engines. The
full-up configuration, with wing and auxiliary jets installed was first flown on 2 Marcn 1964. A level flight
true airspeed of 214 mph was achieved using maximum auxiliary thrust. Contracted testing was
cornpleted in April of 1964. Immediately following the contracted tests, the 2-bladed rotor was fitted
with special tapered tip blades under a Bell Helicopter independent research program. A level flight true
airspeed of 222 mph was attained using maximum auxiliary thrust.
To provide even more thrust, the J69 turbojets were removed and the Model 533 was refitted with
more powerful 1,700 lb static thrust J69-T-29 turbojet engines, the same as those used in the Ryan
BQM-34A Firebee target drone. The significantly increased thrust allowed the aircraft to reach higher
speeds, becoming the first rotorcraft in history to exceed a speed of 200 kt (230 mph), reaching 236
mph on October 15, 1964. Six months later, it became the first ta reach 250 mph in level flight on April
6, 1965. Along with the higher speeds, test pilots demonstrated impressive maneuverability with the
Model 533, routinely performing 26 turns at 60 degrees of bank. Early in 1968, ihe U.S. Army awarded
Bell a follow-on contract with the aim to expand the envelope even further and replace the J69
turbojets with much more powerful 3,300 1b thrust Pratt R Whitney JT12A-3 turbojets. The wings that
had previously been fitted were removed and replaced by a new unswept pair upon which the new
engines were wingtip-mounted. Additionally, the shape of the main rotor fairing was altered. The
longitudinal rontrol system was totally changed, allowing a changeover from standard helicopter cyclic
controls to pure fixed wing elevator type controls. On 15 April 1969, the 533 attained the incredible
speed of 316 mph (274.6 knots) in this configuration. The final test phase of the program involved
replacing the two-bladed main rotor with a four-bladed flex-beam rotor system. At the completion of
testing, the Model 533 was permanently retired, having collected an enormous amount of data for
possible use in future compound helicopter projects. Today, the sole example of the Model 533 is
displayed outside the main building of the U.S. Army's Aviation Applied Technology Directorate (AATD)
at Ft Eustis, Virginia. "

This is truly excellent. But then again, Vertiflite is one heck of a publication!
Thank you so much Jemiba.
Now I have one quarm: why put the Model 533 in a thread about the Model 204 COMPETITORS when it is clearly a DERIVATIVE of the Iroquois?

You're of course right, but it's just a case of drifting OT, I think ... :
And just to come back to the original theme, here's the Hiller Ten99, which
in fact was a contender to the UH-1.

(from AviationWeek 1963-18-25)

Now THAT was one ugly bird! I had almost forgotten about that flying lunchbox!!!

Stargazer2006 said:

Now I have one quarm: why put the Model 533 in a thread about the Model 204 COMPETITORS when it is clearly a DERIVATIVE of the Iroquois?

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Because we want to have the UH-1 stuff in one place and in the same time we don't want the topic title one paragraph long! I modified it, so I hope that now will everybody be satisfied.

Jemiba said:

You're of course right, but it's just a case of drifting OT, I think ... :
And just to come back to the original theme, here's the Hiller Ten99, which
in fact was a contender to the UH-1.

(from AviationWeek 1963-18-25)

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My god
I had worked out of UH-1H Iroquois for a few years before they were replaced by more powerful and capable Blackhawks!
There is no way in hell you would get me repelling out of this thing - let alone under fire!!
Sh*t even if it was a Dust OFF - let me die were I was hit please

Regards
Pioneer

Jemiba said:

And just to come back to the original theme, here's the Hiller Ten99, which
in fact was a contender to the UH-1.

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According to Helis.com, Hiller's entry in the Iroquois competition was NOT the Ten99 (which was developed to a USMC specification, anyway) but rather an improved version of Doman's LZ-5-2 (YH-31), of which Hiller had acquired the rights in September 1953. It is said to have been tested by the US Army but lost against the Bell 204, which became the HU-1/XH-40/UH-1 Iroquois.

However, I find it strange that the type was evaluated against the Bell 204 without any photograph of it around... I also never read any other source supporting the theory that the LZ-5 once became a Hiller design. According to another source, "in order to speed up output for this outlet, Doman decided in 1953 to grant Hiller a licence to manufacture the mechanical components of the military version, while Doman himself continues independently to produce the LZ-5 commercial version" (P.Lambermont "Helicopters and Autogyros of the World", 1958). This is quite a different version already!

Besides, here's what the YH-31 looked like, and quite honestly I can't see how even a stretched version of this could have been considered as a contender for the "Huey"...



Anyway, the LZ-5 continued its career in Italy, being produced as the D-10A by Aeronáutica Sicula SpA in Sicily, and then in Puerto Rico as the Caribe Doman D-10B! (photos below)

Stargazer2006 said:

Oops, from the angle of the very first picture, I figured this was a three-blade configuration, but on closer look, this must be the result of a wide-angle lens, because obviously there are only two blades visible. So maybe there NEVER was a three-blade version after all.

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From everything I know and have heard, Bell stayed with a two-balded rotor until such time as the cheif engineer with the patent on it retired; then they started working on four-bladed rotors and such. From what I've heard, the YAH-63 would've stood a much better chance in the compeitition if had used a four-bladed rotor (something about the large blades of the two-bladed rotor coming very close to striking the canopy).

There was an online ref to the Kaman K-600 Husky being a competitor to the XH-40. Can anyone confirm or deny that?

[BTW Jens, the Ten99 was an LOH competitor]

A slight bit OT, but I've always wondered if the Bell 214(?), that big ol' stretched out Huey relative was considered for the proposal that gave us the Black Hawk. If it wasn't, why not, if it doesn't drag this well OT.

elmayerle said:

From everything I know and have heard, Bell stayed with a two-bladed rotor until such time as the chief engineer with the patent on it retired; then they started working on four-bladed rotors and such. From what I've heard, the YAH-63 would've stood a much better chance in the competition if had used a four-bladed rotor (something about the large blades of the two-bladed rotor coming very close to striking the canopy).

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I knew the man and I can assure you that his patent royalties had no influence on the decision, which was certainly not his alone. (in any event, he was certainly smart enough to know that any royalties on a losing design would be zero.) It is true that they stuck with what they knew best for perhaps too long but they did research on multi-bladed rotors long before he retired. In fact, Bell proposed a four-bladed alternative in their UTTAS proposal, which preceded the AAH competition. Bell senior management, engineering, and marketing were well aware of the two-bladed rotor image problem in the Army and spent a great deal of time evaluating two-bladed versus four-bladed configurations and debating which to propose. Bell picked the two-bladed rotor for the AAH in part because of the vulnerability requirement to absorb a 23 mm round: the wider blade allowed for redundant spars. Since hover/low-speed nap-of-the-earth flight was a high proportion of the mission, the known cruise performance shortfall was considered acceptable. It also simplified preparation for C-130 transportability, since blades did not have to be folded.

The Bell team also decided to put the gunner in the rear seat of the AAH-63 because of the nap-of-the-earth requirement. It turned out that the Army preferred the gunner to be in front as it had been in the Cobra and was in the AAH-64.

All of the AAH and UTTAS contenders had trouble with the low rotor location imposed by the air transportability requirement. The Hughes AAH was the one with the canopy clearance problem and had to raise their mast like all the others. The Bell problem was actually a rotor/tail rotor drive shaft clearance in down slope landings.

Neither the Bell nor the Hughes AAH were ready for prime time due to limited time provided for development and the competitive fly off. My understanding is that the Army technical community thought that there was a better chance that Hughes would fix their problems. For sure the AAH-63 was heavier and slower.

frank said:

A slight bit OT, but I've always wondered if the Bell 214(?), that big ol' stretched out Huey relative was considered for the proposal that gave us the Black Hawk. If it wasn't, why not, if it doesn't drag this well OT.

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Bell proposed two similar new designs for UTTAS, one four-bladed and the other two-bladed. The original 214 was a single-engine helicopter and thus didn't meet the requirement.

elmayerle said:

From everything I know and have heard, Bell stayed with a two-balded rotor until such time as the cheif engineer with the patent on it retired; then they started working on four-bladed rotors and such. From what I've heard, the YAH-63 would've stood a much better chance in the compeitition if had used a four-bladed rotor (something about the large blades of the two-bladed rotor coming very close to striking the canopy).

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A co-worker and former helicopter pilot who's got time in Cobras told me that the 2-bladed teetering rotor does not like being unloaded (maybe that's what leads to tail-strikes). This posed limitations on diving attacks.

AeroFranz said:

A co-worker and former helicopter pilot who's got time in Cobras told me that the 2-bladed teetering rotor does not like being unloaded (maybe that's what leads to tail-strikes). This posed limitations on diving attacks.

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A certain Fort Worth Star Telegram reporter made a big name for himself and got to Washington by hammering away on "teeter rotor, deadly blades" week after week. What happens when you unload the typical gimbaled two-bladed rotor toward 0 G, it starts to flap excessively and worse case, "bumps" the rotor mast. That's a highly stressed part and might fail at that point or soon after. Basically, when it hurts if you do that, don't do that. I've been past 90 degrees of bank many times and nearly inverted a few. The trick is to keep positive G on with neutral or back stick; never, ever push over hard enough to get light in the seat. The incidence of mast failure from mast bumping in the commercial world is pretty close to zero; it became rare in the military after a few fatal accidents and a education program. According to one of the Bell test pilots involved, the AAH-63 met the O G pushover requirement (with an elastic flapping hinge restraint) before the flyoff, and he doesn't think that the AAH-64 did, among other demonstrations.

Does anybody have any information about the project from Dornier that took place during the 80s? It is related to the installation of the 110 mm LLAR rocket launcher to the UH-1D.

Tailspin Turtle said:

A certain Fort Worth Star Telegram reporter made a big name for himself and got to Washington by hammering away on "teeter rotor, deadly blades" week after week. What happens when you unload the typical gimbaled two-bladed rotor toward 0 G, it starts to flap excessively and worse case, "bumps" the rotor mast. That's a highly stressed part and might fail at that point or soon after. Basically, when it hurts if you do that, don't do that. I've been past 90 degrees of bank many times and nearly inverted a few. The trick is to keep positive G on with neutral or back stick; never, ever push over hard enough to get light in the seat. The incidence of mast failure from mast bumping in the commercial world is pretty close to zero; it became rare in the military after a few fatal accidents and a education program. According to one of the Bell test pilots involved, the AAH-63 met the O G pushover requirement (with an elastic flapping hinge restraint) before the flyoff, and he doesn't think that the AAH-64 did, among other demonstrations.

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Tommy, thank you for the exhaustive explanation

I'm faced with a problem which I believe can only be solved on this forum, if it can be solved at all.
I have tried in vain to find a picture of the Bell Model 208 "Twin Delta" demonstrator, which served as a prototype for the famous Bell 212 Twin Huey series. Now there doesn't seem to be any picture available of that rare bird, but maybe someone around here knows where to look? Thanks very much in advance for any help you can provide!

Coming to think of it, my quest for pictures of the Model 211 "Huey Tug" has been equally unsuccessful... Probably related to the fact that these were company demonstrators, not DoD programs...

Bell 208? Not to worry, go to http://www.arcforums.com/forums/air/index.php?showtopic=200876&st=131. Actually, the whole thread is full of weird and wonderful US Army helicopter stuff. Enjoy!

Apparently the earliest concept and first look at the lightweight Bell XH-40, the prototype aircraft which led to the popular UH-1 series. From a page in an unidentified magazine, found on eBay. Sorry, I don't have the link at the moment.
Thanks, Hesham, for encouraging me to post it here. ;D

Here is a series of pics of the Model 533 helicopter.

aim9xray said:

Bell 208? Not to worry, go to http://www.arcforums.com/forums/air/index.php?showtopic=200876&st=131. Actually, the whole thread is full of weird and wonderful US Army helicopter stuff. Enjoy!

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Did I ever thank you for this link? I think I didn't! So a belated thanks to you now!!