Why didn't Sikorsky try a CH-37 with turbines?

[Luther Sebastian]

Why didn't it occur to the engineers to put turbines in place of the radials and get some serious heavy lifting going? It was only went out of service in the late sixties and turbines were commonplace by then.

[Redland]

Westland Westminster was based on the CH-37, it had turbines.

[Fareastdriver]

The CH37 was in production before the GE T58 was running. By the sixties heavier helicopters than the S61 like the CH53 were in the pipeline.
Should they have developed a turbine version the engines would have been closed up to the fuselage so it would have been much like any other but with out-of-date control systems.

[HeliTester]

According to Sikorsky Archives, the CH-37 was designed in response to a US Navy specification. The proposed helicopter was offered with both reciprocating and turbine engines. Apparently it was the US Navy that chose to go with reciprocating engines.

www.sikorskyarchives.com/S+56%20HR2S-1H-37.php (http://www.sikorskyarchives.com/S+56%20HR2S-1H-37.php)

[Ian Corrigible]

Sikorsky S-60 (http://www.sikorskyarchives.com/S-60%20Crane%20Helicopter.php)

http://www.sikorskyarchives.com/images/images%20S-60/S60-1_edited-s_edited-2.jpg

...Which then led to the S-64 (http://www.sikorskyarchives.com/S-64_Product_History%20modX.php).

I/C

[heli1]

Biggest mistake Westland made was to abandon the Westminter in favour of the Belvedere.Westminster was well ahead of the S-64 and could surely have found a good market for heavy lift.
Where are the two prototypes now? Buried under a concrete slab in Charlton Mackrell I believe!

[NickLappos]

Sikorsky did n H-60 with turbines, it was called the H-54 Tarhe, or the S-64 Skycrane. The S-60 was an experimental demonstrator that "sold" the Skycrane to the US Army!
It was Igor's dream, and it worked well. Also, the same rotor technology was used on the CH-53A.
The S-60 was the technology leader for the entire generation of large Sikorsky helos in the 60's and 70's.

[JohnDixson]

Just some guesswork, as I never listened to a conversation of this particular matter:

At that time, there was a close relationship between Westland and SA, dating back to S-51 model days. In this instance, with SA sending S-56 drivetrain parts to be installed in the Minster, the actions by SA to get P&W to put a free turbine on the J-60, such that it flew in 1962 on the S-64, was probably known at Westland. That 4050 SHP engine presaged pretty decent performance, and the S-60, as Nick noted, had already done successful marketing trips to the US Army, so another guess is that Westland saw the one big market for the Minster going to a higher power/performance machine. Ironically, Igor's dream* for a dedicated heavy lift design, sans cabin, has not progressed beyond the initial efforts.

* I have a book by an original SA Sr Marketing guy " Skip " Eveleth : " A Documentary of Igor I. Sikorsky " and it is a series of recorded interview sessions between two old friends. That record makes clear that when Nick used the term, " Igor's Dream ", it was no exaggeration.

[Fareastdriver]

There was a joint US Army and UK Army exercise on Salisbury Plain in the mid sixties. I was there with my trusty Whirlwind Mk10 and the US Army were there with Hueys and CH37s.

We all went for a ride in each other aircraft and whilst I was poling this Mojave around it started to rain, quite heavily. Looking around I noticed the crewman with a big squeegee pushing rainwater down a hole in the middle of the floor. At ceiling level there was a continuous spray coming off the drive shafts going into the gearbox.

The front reminded me of a Bristol Frightener and it was just a draughty.

[JohnDixson]

Fareast, it must have been a design requirement for a time ( just kidding ), because the S-67 and UH-60 ( early on ) exhibited the same troubles. Gets embarrassing when you go down to visit Ft Campbell to make a UH-60 movie with D/158, flying with one of the guys from my Vietnam unit ( 119th ) and its a very rainy day, but the powers that be said the movie might be better for that. Right: you know I looked behind me and it was raining darn near as hard inside as outside. 76 and 92 were far better that way.

[Arnie Madsen]

Connecticut Air & Space is restoring a junkyard S-60

https://www.facebook.com/SikorskyS60?fref=photo

[heli1]

Not just any old S-60 but THE S-60 ,which I recall seeing stored at the New England Air Museum many moons ago. At around that time Peter Wright donated an H-37 to The Helicopter Museum in the UKfrom the junkyard collection he had in Tucson.Sadly the museum couldn't raise the funds to ship it to the UK so like almost all the rest it was eventually scrapped.Shame.

[riff_raff]

Actually, for the CH-37 requirements the R-2800-50 was probably not a bad choice. It produced 1900bhp for a 2300lb dry weight, and only required a 14:1 ratio main rotor gearbox. While the XT-38 of similar output weighed just over 700lb, it also would have required additional gear reduction stages that would likely increase engine weight by 25-30%.

The R-2800 at that time was well developed, very reliable, readily available, low cost (compared to a turboshaft like the T-38), and the USN/USMC were familiar with the engine design.

The R-2800-50's BSFC was well under .50 lb/hp-hr, or about 25% lower than a similar turboshaft of that time. The R-2800 engine/drivetrain would be a bit heavier and bulkier, but the T-38 engine/drivetrain would be less efficient and require a larger fuel load for a given mission.

[Luther Sebastian]

Thanks for all the replies (so far!). It never occurred to me that the main reason for having the engines on outriggers was because they were large radials. I was naively expecting the turbines to go in the same place, but you can have a lot of the same dynamic parts and still end up looking a lot different.

Mind you, what else (with a rotor) could you drive a jeep out the front of?