Talk:Rolls-Royce Olympus

Description

The description of the variable area exhaust nozzle is wrong wrt the Olympus. On this engine the nozzle comprises a series of 'petals', interlinked and surrounded by a ring. The ring contacts the petals by a series of rollers running on shaped (curved) tracks such that as the ring translates forward and backward the petals are forced closer together or allowed to open out under the exhaust flow. When the engine is running 'dry' the nozzle is at its smallest area. When reheat is selected the nozzle opens to maintain the correct pressure ratios throughout the engine. The nozzle area is infinitely variable within the confines of the range of movement of the petals and is scheduled automatically dependent upon a combination of fuel and air flow as well as the pressure ratios within the engine. The 'eyelids' mentioned in the article are in fact thrust reverse 'buckets' that are extended in the exhaust stream on landing to slow the aircraft down. It should be noted tht safety systems prevent the deployment of the buckets in flight and when reheat is selected. Kitbag 23:13, 16 May 2007 (UTC)

G-AXDN, Duxford, close up of pre-production engine nozzles. The nozzle/thrust reverser design was altered for the production Concordes.

The description you mention may indeed be a bit confusing. The 'eyelids' you mention are a part of Concorde's Olympus 593 nozzles, and are used as thrust reversers on landing, however during cruise they actually form part of the engine's variable nozzle, and are only used to divert flow forwards (i.e., towards the front of the aircraft) after landing. During other flight regimes they vary the jet efflux as-per a 'normal' variable nozzle. The more complex nozzles you referred-to were used on the Concorde prototypes (see image), but the simpler 'eyelid' version mentioned above was used on production aircraft. These variable earlier types were used on the re-heated Olympus fitted to the BAC TSR-2, although IIRC, without any form of thrust reverser.

Incidently, the re-heated Olympus fitted to the TSR-2 was originally intended for the projected short-range SST that was later cancelled in favour of the long (transatlantic) range SST that became eventually Concorde. —Preceding unsigned comment added by 86.112.48.14 (talk) 20:50, 25 December 2010 (UTC)

More on the nozzle I noticed the above paragraph which prompted me to do a bit more digging. There were indeed two nozzles, the primary nozzle, which works as described by me, and a secondary nozzle which directs bypass air around the exhaust gases from the primary forming a 'sleeve' that prevents the exhaust plume flaring out with consequent loss of thrust. At this link is a far more detailed, illustrated description, which I think clears it all up. Does anybody fancy a go at creating a simple accurate paragraph on the article page? Kitbag (talk) 18:31, 7 November 2016 (UTC)

Wright J67 Cancellation

Does anyone know why Wright ended up cancelling their J67 while Bristol eventually managed to get the Olympus up to over 40,000lbf? —Preceding unsigned comment added by 213.40.254.24 (talk) 19:31, 26 November 2009 (UTC)

Answer my own question - according to Flight, Wright extensively re-designed the Olympus for 'more power' aiming at a target of 15,000lb of thrust. They got the engine up to 12,000lb and then seemed to have become discouraged, as they gave up on the 'improved' design shortly afterwards. —Preceding unsigned comment added by 86.112.78.10 (talk) 21:12, 22 February 2011 (UTC)

Do you have the issue or archive page for that? Thanks. - BilCat (talk) 21:16, 22 February 2011 (UTC)

I had it a couple of weeks ago - if you hang on I'll see if I can find it again.

Found it - after much buggering-around with Google it was in the article linked on the 'External links' section; [1] —Preceding unsigned comment added by 86.112.78.10 (talk) 21:38, 22 February 2011 (UTC)

According to Flight, Curtiss Wright also intended to market a version of the civilianised Olympus Mk 555 (a derviative of the Olympus 6/Olympus 200) known as the TJ-38 Zephyr. http://www.flightglobal.com/pdfarchive/view/1958/1958-1-%20-%200334.html. To answer the original question, the Olympus evolved through many stages and the later engines had little in common with earlier ones. Bristol's own development of the original Olympus ended with the 104 of 13500 lb thrust - more in line with CW's achievements. CW's problems were largely corporate I understand. XJ784 (talk) 11:11, 25 July 2011 (UTC)

CW also intended to produce a turboprop version of the Olympus as the Wright T47.[2] - BTW, US tests of the initial UK-supplied Olympus were carried out slung under a B-29.[3] — Preceding unsigned comment added by 80.4.57.101 (talk) 22:47, 22 January 2012 (UTC)

Yes according to Stanley Hooker in 'Not much of an engineer'(Airlife books) he had discussions with Roy Hurley from Curtiss-Wright who wanted to build the Olympus but there was internal resistance as Chief engineer at C-W Bill Lundqvist 'was convinced that turbo-compound engines would go on for ever'.Completeaerogeek (talk) 06:22, 10 April 2016 (UTC)

Specifications section

The specs section does not mention the Mk of engine, and the max thrust does not line up with any of the models in the upper section. Can anyone clean this up? Maury Markowitz (talk) 18:23, 6 July 2011 (UTC)

Following the link, the specs section is for the 593, so it's on the wrong page. Does anyone have specs for the 1xx series and 2xx series? Maury Markowitz (talk) 18:32, 6 July 2011 (UTC)

There are some specs scattered around in the Flight article I linked to in the reply above: [4] but you'll probably have to read the whole article to find them - BTW, there are also some specs in a table on the second page with the cutaway drawing [5]. — Preceding unsigned comment added by 86.112.68.219 (talk) 20:16, 21 July 2011 (UTC)

This spec certainly refers to the 593B. The Vulcan engines 100 thru 301 all had cannular combustors though the 'specification' describes an annular combustion chamber. Fwiw, the 100 had a thrust of 10000 lb, the 101 11000 lb, the 102 12000 lb, the 104 13500 lb, the 200 16000 lb, the 201/202 17000 lb and the 301 20000 lb. Details from RR Heritage publication 'Olympus, the First 40 Years' which is good provenance. I'll upgrade this section shortly. XJ784 (talk) 10:16, 25 July 2011 (UTC)

Just a FYI, the Olympus R28 Mk.360 was being worked on when the TSR.2 was cancelled. It was the intended engine for production aircraft, the Mk 320 being intended only for initial test flights. IIRC the R28 Mk.360 was running on the testbed at this time and was rated at 42,733 lbf wet.

The Mk 320 was never intended for other than the (politically) urgent initial flights of the TSR.2, as it suffered from belling frequency problems, i.e, resonance of the spool shafts at certain engine speeds which could lead to catastrophic failure of the engine.

The Olympus R28 Mk.360 definitely did exist and it was the intended engine for production TSR.2s.

BTW, there's a 1959 Flight advertisement for a 24,000lb re-heated Mk 201 Olympus here: [6] — Preceding unsigned comment added by 80.4.57.101 (talk) 20:40, 9 December 2011 (UTC)

I have no idea if the Mk 360 existed or not. Baxter's Olympus, the First 40 Years is perhaps the only dedicated book on the subject but makes no mention of such a development, either in the narrative or in the Olympus Family Tree.

The designation Olympus R28 Mk.360 seems non-standard. A Bristol development designation would have been BOl.28R (Bristol Olympus 28 Reheat). Similarly, Mk.360 sounds more like a flight test engine. Production engines would be Mk.361, 362 etc.

The ultimate military designations given by Baxter, all developments of the BOl.21 Mk.301, are (1) BOl.23 (Vulcan Phase 6), (2) Mk.701 (RB-57F) and (3) the BOl.22R Mk.320/321 (TSR-2, Mk.321 being the initial service designation) via the BOl.21R aka BOl.22DR (development reheat).

As we know with the Vulcan, engine development was always ongoing. However, evidence of this in the case of TSR-2 should have citations and in a brief search I can find nothing as yet to support this. XJ784 (talk) 15:23, 10 December 2011 (UTC)

Further to this, the following can be found in the National Archive/Coventry Archive PA176/5/11/19:

Olympus 320 Final Development Position PA1716/5/11/19 15 June 1965

1 item

Contents:

Report on the final development state of the Olympus 320 engine at cancellation of the project.

It would be interesting to retrieve the report which might resolve the matter. There are numerous references in the file to all marks of Olympus but nothing about a 360, R28, 28R etc. XJ784 (talk) 14:56, 13 December 2011 (UTC)

Thanks for the reply. Unfortunately I cannot remember where I read of the R28 Mk.360 but I remember originally adding it to the page before the page was expanded and I'm pretty careful with those sort of details. It may have been taken from TSR-2-related files at TNA (formerly KEW PRO) that were declassified only in the past few years or so. Files relating to TSR-2 were due to be declassified back in the 1990s but were found to be contaminated by asbestos, so these files had to await de-contamination, and the files weren't copied and eventually released until a couple of years ago. I'm pretty certain I got the details on this engine from there but like I said, can't be sure. I only added them to the page so that someone more interested might be able to use the designation and ratings for research elsewhere. If I come across the information I'll get back to you but I think I may no longer have it. — Preceding unsigned comment added by 80.4.57.101 (talk) 18:43, 22 December 2011 (UTC)

... "Olympus ... with development potential to 40,000 lb plus" - from here [7] — Preceding unsigned comment added by 80.7.147.13 (talk) 15:46, 26 May 2013 (UTC)

Page updated

I've updated most of the page using Alan Baxter's book as the major reference. May be a tadge wordy. Comments, amendments etc most welcome. XJ784 (talk) 15:26, 4 August 2011 (UTC)

Other Proposed Aircraft Applications

I've read somewhere that the Olympus was proposed for the SAAB 37 Viggen. Might be worth mentioning. 83.248.178.222 (talk) 04:37, 8 August 2011 (UTC)

The not-always accurate WP gives an association with the Saab 36 which seems sensible. If the text on the Viggen is accurate, then a turbofan was always the proposed powerplant XJ784 (talk) 08:49, 8 August 2011 (UTC)

OK, that makes sense. But I'm still sure that I've read somewhere that the Olympus engine was proposed for the SAAB 37 Viggen. After using Google I found this article in Protec: Historien om Viggen. (Protec is a magazine from FMV and a reliable source.) The text reads "Flygplanet var då delvis förändrat gentemot de ursprungliga planerna. Bland annat hade man bytt ut den tilltänkta Olympusmotorn mot en utvecklad version av den civila JT8-D-motorn från amerikanska Pratt & Whitney." which roughly translates 'The airplane was partly redesigned and the Olympus was replaced by the JT8-D from Pratt & Whitney.'. 83.248.178.222 (talk) 04:15, 9 August 2011 (UTC)

Good spot! Will add to list. XJ784 (talk) 09:14, 9 August 2011 (UTC)

Original engine choice for the Viggen was the RB177 but this engine was cancelled. A scaled-down version was later built as the Spey. — Preceding unsigned comment added by 80.7.147.13 (talk) 14:03, 1 January 2013 (UTC)

Applications

Olympus are also used by many powerstations to quickly produce a lot of power in times of high demand or during a power cut — Preceding unsigned comment added by Fdsdh1 (talk • contribs) 15:30, 7 July 2012 (UTC)

Yes, that is mentioned at Rolls-Royce Olympus#Industrial Power Generation. Thanks Nimbus (Cumulus nimbus floats by) 19:16, 7 July 2012 (UTC)

"The Olympus was the world's first dual-spool axial turbojet"

I think this statement could be misleading since the P&W JT3-8 and J57 were the first to run (June 1949 and Jan 1950, Olympus May 1950) and the J57 the first to enter service (June 1955 B-52B). It seems to refer to paper studies done at Bristol when, in November 1946, two axial compressors were acknowledged as the right way to go for long range jet aircraft, Baxter p.16 or Flight 9 Dec 1955 p. 871. This engine configuration was not pursued at P&W until Sept 1948 when a new proposal for a B-52 engine was required. This helped clarify my understanding of the statement in Flight 9 April 1954 " Olympus ..first two-spool.. in world antedating...J57 by some two years" ie the source for the original statement.Pieter1963 (talk) 19:59, 22 March 2015 (UTC)

What is the reference for the J-57 running earlier than the Olympus? The JT series of P&W engines were based on the J-57 which appears to have first run in 1952 and entered production in 1953. P&W makes no claim to being first in their official history. Please cite your reference for this.Completeaerogeek (talk) 06:23, 10 April 2016 (UTC) "

From P&W own website timeline: "1950 - Barred from developing jet engines during the war years due to the high demand for piston engines, Pratt & Whitney opens the Andrew Wilgoos Gas Turbine Laboratory for jet engine testing—the most advanced facility of its kind." - See more at: http://www.pw.utc.com/Where_Weve_Been#sthash.8Q8Xl9yT.dpuf Completeaerogeek (talk) 07:29, 10 April 2016 (UTC)

Further to this from 'Not much of an Engineer by Sir Stanley Hooker -Airlife publishing 1984/2010 p 140 In the chapters on the Olympus: "It was the first real two spool engine in the world" "...and there for all to see was 10,000lb thrust." Hooker p 142. This was early in its test program (mid 1950) with Roy Hurley from Curtiss-Wright in attendance ( Hooker p 142)

The Olympus clearly appears to be the first dual spool engine and the first to run to 10,000lb. P&W makes no claim to either of these in its official statements which would be extremely unlikely if it were true.

I have emailed Pratt & Whitney media relations for a J-57 timeline but every reference I have says the J-57 ran in 1952.

On this basis the claims for the J-57 seem impossible particularly as P&W only opened then engine design and test facility in 1950.Completeaerogeek (talk) 08:18, 10 April 2016 (UTC)

Actually, the twin-spool JT3-8, an early development of the J57, first ran in 1949, though it was not very good, and was a long way from the final J57 (JT3A) design which ran in January 1950. P&W was already producing jet engines before 1950, notably the J42 and J48 under license from RR. It had also begun development of several of its own gas turbine designs in 1944. For a good source on Pratt & Whitney gas turbine engines, see The Engines of Pratt & Whitney: A Technical History (2010) by Jack Connors. - BilCat (talk) 15:51, 12 April 2016 (UTC)

Hello Completeaerogeek "It was the first real two spool engine in the world" seems at odds with the actual run dates. But that's only if we choose to interpret it that way. It doesn't say "first" with regard to anything specific. Olympus by Alan Baxter (RR Heritage Trust Series) is more helpful I think. The Hooker statement was written referring to the state of things in 1949 ie 2 pages before his account of the first run. The Baxter book tells us that at that time the Olympus existed as a paper design configuration which dated back to 1946 with calculations indicating the superiority of the twin axial arrangement. So the paper engine is my interpretation of his 'first'.Pieter1963 (talk) 14:40, 2 May 2016 (UTC)

The original P&W J57's, the X-176 (JT3-8), and X-184 (JT3-10) performed very poorly and so they were re-designed into effectively a new engine, which became the JT-3A, this first running on 21st January 1950.

The first two spool engine was not a turbojet, but instead was a turboprop, the Rolls-Royce Clyde.

BTW, the initial published thrust figure of the Olympus corresponded to the height in feet of Mount Olympus in pound's of thrust, although Hooker stated the engine gave more than 10,000 lb thrust on its first run.

backwards?

It says: "The design was progressively modified and the centrifugal HP compressor was replaced by an axial HP compressor. This reduced the diameter of the new engine to the design specification of 40 in (100 cm)" Ive never heard of an engine that used an axial LP compressor and a centrifugal HP compressor. Usually it's the other way around. Why would you start with a narrow, multi-stage axial compressor capable of high pressure ratios, and then send the product into a wider, bulkier, single-stage centrifugal compressor capable of only moderate compression ratios? Usually you start with the moderate single-stage centrifugal compressor to give an initial compression to the intake charge and then put it through the multi-stage, high-ratio axial compressor to prepare it for the combustion chamber.

64.222.204.75 (talk) 20:34, 31 May 2020 (UTC)

It is correct. The original idea was based on the company's previous experience with compressors, ie the Bristol Theseus engine.

I have never heard of.... Axial LP and cf HP is today, and always has been, common for smaller engines, eg for helicopters and business jets.

...then send the product into a wider, bulkier... It's not really that bad because the cf flow passages can be to be relatively small because the specific volume of the air has been reduced by the axial compressor. This is not intuitively obvious so the best visual appreciation can be had by comparing like with like, ie an LP cf followed by an HP cf. See the relative impeller sizes in Fig.6. If you look at Fig.7 you will see axial plus cf. Note that it's not the diameter of the cf impeller that is significant, as far as diameter goes. It's the stationary second part of the cf stage which adds to the diameter. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.600.8607&rep=rep1&type=pdf

capable of only moderate compression ratios cf compressors are renowned for high pressure ratio per stage.Pieter1963 (talk) 17:55, 3 June 2020 (UTC)

Variants section - split to separate article

As the header, the variants section has recently expanded and is squeezed into an odd three column format. I propose to create a new variants article unless there are objections. Nimbus (Cumulus nimbus floats by) 19:09, 15 November 2020 (UTC)

The variants article has been created, text was copied without editing so that attribution can be seen in both this and the new article. Nimbus (Cumulus nimbus floats by) 17:38, 18 November 2020 (UTC)

The name...

"BOl.1 (Bristol Olympus 1)..." - is that Oh-ell for Olympus? The font makes it not entirely obvious. Maury Markowitz (talk) 19:41, 26 August 2021 (UTC)

See WP:EXPABBR: "do not emphasize the letters that make up an an acronym, initialism, or syllabic abbreviation", and also MOS:NOBOLD. BilCat (talk) 21:28, 31 August 2021 (UTC)

@BilCat: That doesn't answer my question nor address the problem. Maury Markowitz (talk) 13:06, 1 September 2021 (UTC)

Probably an ell, the Orion turboprop was BOn.1, the Orpheus BOr.1 GraemeLeggett (talk) 13:17, 1 September 2021 (UTC)

Standard UK Ministry of Supply designation indexed in most Jane's directories. Capital letters for the manufacturer followed by the first two letters of the engine name with the first letter capitalised, followed by the name. Bristol Siddeley Stentor, BSSt.Stentor, Bristol Orpheus, BOr.Orpheus, Rolls-Royce Conway, RCo.Conway. Nimbus (Cumulus nimbus floats by) 14:23, 1 September 2021 (UTC)

Then this needs to be mentioned. Again, at least on my display, the lower-case L appears to be an I. Maury Markowitz (talk)

The first line of the 'Initial development' section starts with The first engine, its development designation being BOl.1 (Bristol Olympus 1).... Nimbus (Cumulus nimbus floats by) 14:46, 2 September 2021 (UTC)

And the first line of the article states "originally the Bristol B.E.10 Olympus", which makes it rather unclear indeed. I'm still utterly failing to see why we are not allowed to explain the name, the only argument is from a MOS entry that states we should give the reader the benefit if the doubt, but if I find it unclear then I suspect the same is true of others. Maury Markowitz (talk) 16:17, 2 September 2021 (UTC)

Is this cannular?

"The combustion system was novel" - was it? I seem to recall lots of engines of this era using cannular systems, isn't that what is being described here? Maury Markowitz (talk) 19:38, 31 August 2021 (UTC)