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Author Topic: Rolls Royce Viper/ Bristol Siddeley Orpheus  (Read 25801 times)

Offline kaiserbill

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Rolls Royce Viper/ Bristol Siddeley Orpheus
« on: January 21, 2012, 05:33:31 am »
What was the most powerful version of the Viper to see service? Was it the Viper Mk 680-43 rated at 4400 lbs (19,57kN) as used in the MB-339?
 
Yugoslavia and Roumania also developed the SOKO/IAR Orao featuring 2 afterburning Viper Mk 633-47, featuring 4000lbs ( 17,79kN) dry thrust, and 5000lbs ( 22,24kN) in afterburning.
 
Was there any move to have an increased dry thrust Viper at any stage? I seem to recall Bill Gunston mentioning a Viper with increased thrust. Did Rolls Royce test any more powerful versions?
 
Were Yugoslavia and Roumania intending to develope the engines in the Orao any further?
 
What was the comparison like between the Viper and the Bristol Siddeley Orpheus? The Orpheus was the later engine to run by about 6 years, had more thrust (the Orpeus 803 had 5000lbs thrust).
It had fewer turbine and compressor stages, thus was simpler.
 Was there a reason the Viper was in production for a much longer time? What were the specifications for the Viper 680 vs the Orpheus 803?
 
 
 

Offline JFC Fuller

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #1 on: January 21, 2012, 05:47:15 am »
This might help:


http://www.secretprojects.co.uk/forum/index.php/topic,769.msg98808.html#msg98808


BS seems to have poured intellectual resources into engines of limited return, BS.53/100 and later supersonic Olympus derivatives (which were almost killed before birth in the 50s) to the detriment of more commercially viable engines such as the BS.75, BS.123 and later Viper variants- but then MoS was paying for VSTOL.


See also: [size=78%]http://www.secretprojects.co.uk/forum/index.php?topic=11633.0[/size]

Offline kaiserbill

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #2 on: January 21, 2012, 04:28:45 pm »
Thanks Sealord. I'll have a read through that now.

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #3 on: January 23, 2012, 09:46:30 am »
The Viper and Orpheus originated in different 'stables' and at different times... the Viper aerodynamics came from the Adder which was a turbojet based on the Mamba, so was an engine of 1940's origin. Orpheus was not started until the early 50's and was designed at a higher thrust point which makes it a little larger than the Viper. Viper was a lightweight engine that evolved into primarily a business jet and military trainer engine with other spin off applications. The Viper 600 series engines were a Bristol Siddeley development so incorporated the thinking of Bristol's designers.
The cutaways at the same scale show how the ASV. 3 of 1,640 lbt evolved into the 600 series of 4,000lbt with perhaps an inch extra on diameter. The ASV.3 had 7 st compressor ann combustion chamber and single stage turbine and weighed 375 lb; beefed up for conventional (non target drone) applications the ASV.5 weight went up by 90lb for same thrust.
The 600 series is really a new engine (see cutaways) and is 4,000lbt  for a weight of 784 lb in the civil version; 8-stage compressor and 2 stage turbine and a much shorter combustion chamber are features of the redesign.
The Viper ASV.10 is a typical uprated first generation long-life engine.

"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline kaiserbill

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #4 on: January 25, 2012, 03:23:19 am »
Thanks Tartle, very interesting.

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #5 on: January 29, 2012, 03:02:28 pm »
Kaiserbill... useful to get feedback...
I've now found time to scan in some more of my Viper 'stuff'. The attached pics show the evolution of the Viper 11 into the 600. Inspection of the drawings should reveal how the technology deployed was updated over the years.
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #6 on: January 30, 2012, 02:35:14 am »
The first Viper to run, was a Viper 2, in April 1951, design having commenced in 1948. It was for the Jindivik target drone which was intended to have a 15 min sortie at 40,000ft. It  passed a special 10 hr type test later in the year at a rating of 1640 lbt. A modified Viper 3 managed to pass a 150 hr type test in June 1953. As a result the Ministry ordered the Viper 5 for the Jet Provost... the same aerodynamics but strengthened components and a new fuel system, oil system that was self-contained and a remote drive for accessories.
The Orpheus design did not commence until the end of 1953 and came out of a Saturn engine project, 1950-52, intended to be a lightweight engine for the Folland Gnat. In the event the ministry did not support the Saturn and anyway resources were being sucked into the Proteus development programme which was not going smoothly. The Folland lightweight fighter therefore became the Midge and flew with a Viper 5 engine; it went supersonic in November 1954. The Viper programme now concentrated on improving life and performance. Raising the rpm meant increased mass flow and hence thrust. Also component development allowed higher t.e.t. so pushing thrust up. Tweaking the compressor blades allowed better chics (characteristics) and so performance improved again. These modifications in aggregate produced the Viper 8 which had a thrust of 1750lb; type tested in Aug, 1958. By 1962 450 Viper 8 engines accumulated 110,000 hrs running and service lives on critical sub-assemblies were very respectable.. 2,000 hrs on combustion chambers, for instance. Increasing the tet over this period resulted in the Viper 9 variant with a thrust of 1900 lb. More performance could only be achieved on the existing engine by reducing service life so thoughts turned to a redesign.
The Viper 10 was run, with much improved aerodynamics and improved construction. This engine delivered 2,000 lbt in Dec, 1956. An uprated version the Viper 11 delivered 2,500 lbt.
As a private venture Bristol looked at future civil/military applications and decided there was a market for a an engine of 3,000 lbt with scope to be grown for future aircraft versions. This led to the development of the Viper 20 (mil) /520 (civil), which had a transonic zero stage on compressor, raising mass flow by 20% and also increasing pressure ratio. The tet was reduced by 30 deg to 1070 deg K.  to enable growth potential and greater civil service life. (In material terms a change in metal temperature on the turbine blades of 10 degC approx will halve or double creep life).
The Viper 600 was the ultimate development of this very successful engine. The Italian MB 339 had the ultimate version .. the Viper 680 that had a thrust of 4,300 lb.
... so on to the Orpheus........ which finally ended up as part of the Pegasus!
« Last Edit: January 30, 2012, 12:48:24 pm by tartle »
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline kaiserbill

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #7 on: February 01, 2012, 08:57:35 am »
That is fantastic feedback indeed, Tartle.
 
Very much appreciated.  The Orpheus powered the Gnat/Ajeet, Fuji trainer and the Fiat G91. Not a bad total I suppose, but not nearly the production run enjoyed by the Viper.
« Last Edit: February 01, 2012, 09:06:09 am by kaiserbill »

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #8 on: February 02, 2012, 06:39:49 am »
Onto the Orpheus.. I am writing about a 1909 engine so I will do this with a tbc note on it if I break off!
The Orpheus originated from project work in Bristol's design office on the Saturn. Saturn started off as an idea for a lightweight expendable engine for a stand-off bomb or guided missile. The thinking at that time was that a subsonic speed coupled with very high altitude and reasonable range would 'do the job'. Scheming on the first configurations, known as the B.E.17, started in 1950 and was supported by a Ministry contract. The project was led by Frank Owner in design and Fred Whitehead in production. They led the team to investigate ways of creating a very light low life engine (Rolls-Royce were doing similar with the RB 82) . It was essential that manufacturing were involved from the start as lightweight engines are designed to benefit from non-conventional approaches to the fabrication of the necessary structures. The project ended with the creation of a brochure that detailed the engine layout and manufacturing methods to be used to help achieve light structures and details of the factory necessary to produce them economically. At this point the project ceased and the B.E.17 - a 3,000lbt, 500 lb weight and 500 cost (if produced in batches of thousands!) was never produced as hardware.
Meanwhile Folland had started a design investigation, under the leadership of William Petter, their new boss (he had moved from English Electric after acting as chief designer for the Canberra and P.1) into a lightweight fighter... he talked with Bristol who suggested a more robust version of the B. E. 17 would philosophically be a match for his Gnat ambitions. January 1952 saw Bristol start the design of the B.E.22 for the Gnat. Both firms starting their projects as private ventures. The lighter than conventional engine design was named Saturn and was designed to deliver 3,750 lbt for a weight with accessories of 730 lb. The single shaft engine cofiguration was:
8-stage axial compressor, cannular combustion chamber, 2-stage turbine.
At the end of 1952, the Ministry of Supply said it could not support either project and with Bristol's full committment to the challenges of the Proteus meant Saturn was shelved.
As we saw previously, the Gnat became a Midge and the Viper took Saturn's place.
As yet I have not found a scheme or other drawing of Saturn.
« Last Edit: February 02, 2012, 04:17:41 pm by tartle »
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #9 on: February 02, 2012, 04:39:31 pm »
But all was not lost....
The end of 1953 saw a NATO Ground Support competition NMBR-1 begin; Saturn was revived to serve as a powerplant in the British entrants to the competition. This is a list of entrants:

France  Breguet     Br.1001 Taon
France  Dassault   Etandard XXVI
Italy       FIAT           G.91
France   SIPA           S.800
UK         Avro            727
UK         Folland       F.O.41 Gnat

Since the Saturn had not progressed beyond the initial design phase Bristol's design team, under Stanley Hooker's leadership, decided to speed the process up, and keep costs lower, by redesigning the engine to use the existing low pressure compressor system of the Orion turboprop. and the engine was renamed Orpheus. The Orpheus 1 made it to the test beds and first ran on 17th Dec 1954, at a thrust of 3,000 lb and completed its 150 hr type test in May 1955 at 3,285 lbt.
« Last Edit: February 03, 2012, 04:51:27 am by tartle »
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #10 on: February 03, 2012, 02:32:02 am »
The Orpheus became a recipient of funding under the Mutual Weapons Development Programme agreement that involved the Gnat (1st flew 18th July 1955), Etandard VI (1st flew March 1957), Fiat G91 (1st flew Aug 1956) and the Taon (1st flew July 1957). The Orpheus powered all these aircraft. The Gnat was modified to accommodate the larger diameter tailpipe, dictated by the switch from Saturn.
The Taon turned out to be a fast aircraft; powered by an Orpheus 3, it twice set up a 1,000km closed circuit record... the second occasion, July 23rd 1958, was at an average of 608 mph at 20,000 ft.
The development of the Orpheus financed by the Americans as the only suitable engine available for the Programme proceeded apace; The BOr1 was type tested in Jan 1956 at 4050 lbt. Development of the Orpheus soon resulted in the BOr2 type tested at 4250 lbt in Nov 1956. Fitted with a larger accessory wheelcase it went into production as the BOr3 or Mk801 after passing a type test at 4850lbt in May 1957, primarily for the G91, which won the NATO competition. For trainer use the engine was derated by reducing tet and rpm to yield the 4230 lbt BOr4.
The 801 was uprated to 5,000 lbt and as the 803 passed type test in February 1959. The Mk 803 was made at Bristol and also by Fiat and KHD.
Talks with the Indians had resulted in the selection of the Gnat for the IAF, to be manufactured in India at a new factory in Bangalore. So Hindustan Aircraft Limited came into being, where the Orpheus was produced and overhauled under licence, signed 15th Sept 1956. The first engine came off the production line in Nov 1960, the first Indian Gnats were powered by Bristol-built engines which entered service in Jan 1958.  Later the engine also powered the HAL HF 24 Marut fighter.
Originally the Marut was to have an afterburning version of the Orpheus 12. This engine was a major uprated version with an extra transonic zero-stage to increase mass flow. The turbine became a 2-stage design. The design rating was 6810 lbt and this was achieved in a simulated type test in March 1959. A year later the official tt was achieved. With full reheat the engine achieved 8650 lbt and a simplified reheat gave 8170 lbt.
The Marut did not proceed with this aprated engine and Nato uprated aircraft also did not proceed with th Orpheus 12 engine.
« Last Edit: February 03, 2012, 04:52:41 am by tartle »
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #11 on: February 03, 2012, 04:50:03 am »
The Orpheus engine was selected to power the prototype Lockheed Jetstar as suitable American engines were not available. The picture shows the first prototype fitted with two 4,850 lb (2,200 KG) s.t Bristol Orpheus 1/5 turbojets. It first flew September 4, 1957. The production aircraft were fitted with four 3,000 lb (1,361 kg) s.t Pratt & Whitney JT12A-6 turbojets. This was because of engine out performance requirements.
Other highlights of the Orpheus development programme are shown on a graph published in Flight 13 Feb 1959.
« Last Edit: February 03, 2012, 04:57:51 am by tartle »
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #12 on: February 03, 2012, 10:35:45 am »
 In 1956, a French aircraft designer named Michel Wibault, well-known for his pre-WW II designs, proposed a VTOL aircraft named the "Gyroptere".  He was interested in building a combat aircraft that would be able to operate independently of airfields, which were clearly vulnerable to immediate destruction by Soviet nuclear strikes on the event of a general European war.
 The Gyroptere was to be fitted with a British Bristol "BE.25 Orion" turboshaft engine, with 8,000 horsepower, fitted the rear fuselage to drive four blower units, two on each side of the aircraft and arranged around the center of gravity.  Each blower would be in a moveable snail-shaped casing that could be rotated to provide vertical or horizontal thrust.
 Wibault tried to promote the Gyroptere with both the French and American air forces and got nowhere.  Finally, he approached the Paris-based "Mutual Weapons Development Program (MWDP)", an American-funded NATO office that promoted technologies useful for European defense.  The MWDP's chief, US Air Force Colonel John Driscoll, found the concept interesting, and passed it back to the NATO "Advisory Group For Aeronautical Research & Development (AGARD)" for comment.
 AGARD's chairman was Theodore von Karman of the California Institute of Technology, and one of the most prestigious figures in aerospace.  Von Karman was very intrigued by the idea.  Encouraged, Colonel Driscoll then passed the concept on to Bristol Aero Engines back in the UK.
 Bristol's technical director, Sir Stanley Hooker, found Wibault's lash-up clumsy and inefficient, but he liked the basic idea of using a single engine for both vertical lift and forward flight.  Other VTOL experiments at the time had separate sets of engines for the two purposes.  Hooker assigned a small research team consisting of Gordon Lewis, Pierre Young, and Neville Quinn to investigate the idea.
 The research team quickly concluded that Wibault's idea could be greatly improved by using the using the airflow of the engine itself, directed through swivelling exhausts, instead of a set of external blowers.  They then gradually refined the idea
Their first design concept, designated the "BE.48", was described to Hooker in a memo dated 2 August 1956.  The BE.48 simply extended the Orion's shaft forward to drive a large compressor turbine at the front of the engine, something like that of a modern high-bypass turbofan engine, to drive airflow through a pair of elbow-joint swivelling exhausts immediately behind that.
The memo suggested that the first two compressor stages of the Olympus BO1.21 could be used for the forward fan.  The turboshaft's rear exhaust remained unchanged, with the airflow straight out the back.

This concept was quickly changed to the "BE.52", in which the Orion was replaced by a modified version of the smaller and simpler "Orpheus" engine, and the large compressor fan was more tightly integrated with the rest of the engine.  The scheme provided just as much thrust, maybe even a little more, than the Orion-based concept.  Versions with straight or swiveling exhausts fitted to the rear of the engine were considered.

The next concept, the "BE.53", was similar, but the large compressor fan was changed so that it rotated in the opposite direction from the main compressor spool, eliminating gyroscopic effects that could be a nuisance in a VTOL aircraft.  The BE.53 was described in the initial patent for the new type of engine, dated 12 January 1957.  The GB patent 881663 was applied for by Michel Wibault and Gordon Lewis on January 29th 1957,. It was published on 8th Nov 1961....tbc
« Last Edit: February 04, 2012, 02:57:08 am by tartle »
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline tartle

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #13 on: February 04, 2012, 03:07:21 am »
At this stage Bristol had an engine but no aircraft to put it in! Stanley Hooker went to  Paris to show the BE.53 concept to Driscoll and von Karman, who were both enthusiastic.  Driscoll left the MWDP soon after Hooker's visit, but his successor, USAF Colonel Willis "Bill" Chapman, was just as enthusiastic.... but still no application was apparent.
In early 1957, Hawker Aircraft's chief designer, Sir Sydney Camm was attending the Paris Air Show.  There, he chatted with the Hawker representative in France, Gerry Morel,Camm mentioned that he was unimpressed with most of the "lift-engine" VTOL schemes being put forward at the time, and Morel told him about Hooker and Bristol's schemes. As Camm was concerned about Hawker's future, Camm reasoned, a VTOL combat aircraft might stimulate their interest.
 A few days later, Bristol's Hooker got a letter from Camm that read:
   Dear Hooker: What are you doing about vertical take-off engines? Yours, Sydney 
-- and a few days later Camm got back an envelope containing the BE.53 technical brochure.  He passed it on to his engineering staff, and in due time got back a preliminary sketch of a VTOL aircraft.  Some time later, in early March 1957, Camm then gave Hooker a call who reported that the conversation went:  "When the devil are you coming to see me?" Camm said.
 "As soon as you like of course. But what is the subject?" Hooker replied.
 "It's vertical take off!  I've got an aircraft for your BE.53!"

Hooker and members of his team turned up in Kingston the next day, where Camm showed them the first drawings of the P.1127.
So 1958 saw the start of the detail design of the BE.53 and P.1127 supported by a 75% funding agreement with MWDP. The respective boards of Bristol and Hawker Sideley agreed, in the absence of Ministry interest, to fund the other 25%.
Hooker has described how they basically took an Orpheus and put a shaft through the engine to link the two stage lp compressor with the two-stage lp turbine.
Camm remeberd the Sea Hawk bifurcated exhaust and realised if the engine had this instead of nozzles at the end of the jetpipe then all thrust would be as close to the aircraft's CoG as practicable and so the configuration was born that we recognise today.
The engine was sized to give around 11,000lbt and it was thought a commercial version with conventional exhausts would be interesting... thus the BE.58 was born... it turned out to sit just where RR P&W etc had engines already under development so there were no potential customers for it and it died.
As more power was required for the P.1127 as it was detail designed and weight estimates crept up., Hooker went for a zero-stage on the lp compressor... to make it easier to fit he designed it as an overhanging transonic fan with no inlet guide vanes, which eliminated the need for anti-icing of the vanes, so increasing air through the engine with consequent thrust and/or tet benefits. Also the rotation of lp compressor was reversed to reduce gyroscopic effects on the aircraft. The overhanging fan is common on all fan engines today.
The MWDP liked what they saw and so the Pegasus powered Kestrel was borne. [I have attached  a low-res scan of my cutaway as it shows the overhung fan more clearly than Flightglobal's cutaway -also attached]
« Last Edit: February 04, 2012, 08:11:40 am by tartle »
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline kaiserbill

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Re: Rolls Royce Viper/ Bristol Siddeley Orpheus
« Reply #14 on: February 04, 2012, 03:21:14 am »
Excellent Tartle!
 
That Orpheus 12 sounds interesting.