Bristol Siddeley Turbofans

Bristol Siddeleys efforts at Turbofans have long fascinated me, the company clearly made remarkable progress in its development of the V/STOL pegasus series and the BS.100,but what did with that technology has always puzzled me. So, with some scanning through the flight global I have assembled the following.

From the BE.53 (later the Pegasus) the developed the BE.58 which was essentially a straight-through BE.53, this was then shrunk down to create the BS.75 that ultimately made it to the hardware stage and would have been a logical orpheus replacement.


At the other end of the spectrum Bristol Siddeley undertook a series of studies that led the BS.123 proposal for a turbofan with thrust in the 30-40,000 lb range. Essentially this study was for an engine that would mate the front end of the BS.100 with hot end of the Olympus. The BS.123 was cooperatively studied with SNECMA, at least for a period.


BS.123 data from Aviation Week 1965:

[30-40,000lbs]*...thrust and have a bypass ratio of 3 to 1 and a pressure ratio of 25 to 1. The BS.123 intake diameter is 62 in. and over-all length is 124 in. The two-stage low pressure fan leads into a bypass duct and a 14-stage high pressure compressor.

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*JFC Fuller guess based on other sources.

Remember that BS were teamed with PW on the JT9D and witrh SN on the M56 before GE.

Bristol was perceived in MoS to have done a better job with Olympus 100/200/Vulcan than had ASM with Sapphire/Victor 1 or RR with any-Avon. Conway, pedigree back to Halford's 1946 Napier E.131, was selected 1951/52 for Valiant B.2 and V.1000, cancelled through no RR blemish, then part-Launch Aid Treasury-funded 1956 into 707-420 opportunistically to defuse xenophobic objections to buying Boeing. RR then displaced Olympus 200 from Victor B.2 by offering a fixed price Certification/Production package. With that underway they pitched RB.141/142 Medway far and wide, winning 727 in 1959.

Baseline in EE and other GOR.339 (TSR.2) tenders, Medway was displaced by MoS, 1959, in the selected platform. Many retain a fond notion of clout enjoyed by RR (think of the RR/Hives photo in MoS DGEng, Bulman's, office): not so: unclout. No underlying financial resilience compared with Bristol and (ASM) HS Group. MoS' logic in shotgun-uniting them as BSEL was leg-up to match the general business mass of United Technologies (PW), GM (Allison), GE.

So: TSR.2/B.Ol.22R; Concorde B.Ol. 593 followed as a "variant" of a well-funded type, and influenced by, ah, history of discord, RR:SNECMA (not sure why: Avon did not lose to ATAR in Mirage IIIOz till after 593 won Concorde). Patchway became BSEL-lead R&D site; BS.100 followed logically from BS.53; RR was washed up. US MWDP 75%-funded BS.53, passed data to PW...that contact led to BSEL discussion on work-share for the big fan that lost to GE on C-5, but was selected as JT9D by loser Boeing for (to be) 747. Free of any risk or taxpayers' money, BSEL was right up there with RR's command of Big, funded by us from 1963 as RB.178/207. Quite evidently, as 1965 opened, BSEL was ontrack to takeover such windfall bits of RR as might appeal, and was already joint on some of RR's FRG V/STOL schemes.

Bereft of expectation after 6/4/65, 50% equity/practical control of BSEL on 7/10/66 was happily unloaded to Spey-flush RR by Bristol Aeroplane (HS Group dumped their 50%, 1/68). RR instantly jilted PW; SNECMA had been on that team: they found GE and have thrived on CF6/CFM56. RR defined Patchway as Military Centre of Excellence: all Big Bristols drooped.

all Big Bristols drooped

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Only if they are incorrectly supported!

Seriously though, Andrew Dow's Pegasus book has lots about all this:

http://www.amazon.co.uk/Pegasus-Development-Operational-Vertical-Take-off/dp/184884042X

Ken,

Whilst the selection of the Conway for the V.1000 is common knowledge this is the first I have heard of it being proposed for the Valiant B.2, I know that it was suggested for some of the later and more fanciful designs but my impression was that the B.2 was always intended for the improved Avons that it actually flew with? What is your source for Conway being chosen for Valiant B.2?

Buttler/Bombers,P.42: 17 B.2 ordered 10/51.."a later (LR) version would have...Conway". All were converted 9/52 to Avon/B.1s.

Hives had recruited Dr.AA Griffiths from RAE, 6/39 ("almost a Delphic Oracle" Bulman,RRHT,P.308) and made him Chief Scientist (in Britain's eponym down-to-earth rude mechanical). He was kept off AJ.65 and given lightweight schemes (to be expendable Soar) and, after its transfer from Napier, the augmented flow (by-pass) notion derived from W2/700, and MoS-funded 1950 as RB.80.

AJ Pierre (an American), Nuclear Politics,OUP,1972, has Attlee as ever-hoping that UK research would master the atomic Art, but that US Aid would provide the Article: P.153: "until the Korean War (and resultant cascades of $, Attlee) hesitated to commit (to) the nuclear bomber force...willingness to leave strategic bombing to US". P.154: "the decision to give priority to the creation of the V-bomber force...co-incided with (Churchill's) adoption of the nuclear deterrent strategy in 1952". (So, I deduce Nov.,1950 Spec B.104D/Valiant B.2 was to be Pathfinder...for SAC, and to be fitted asap with the only powerplant that could offer range with a hefty low level sector. B.2 was confined, Sept,1952, to one in build Avon-prototype, to concentrate on delivering part-US MSP-funded B.1s. Some B.(P.R.)1s would suffice to show the way.

I have the first Valiants (25) being ordered in April 1951, with Vulcans and Victors following. A lack of commitment prior to 52 would fit with the internal debate that was ongoing about the utility or otherwise of the force.

In 1955 (From Richard Moore 'The Royal Navy and Nuclear Weapons' pg.105), the Deputy Chief of the Air Staff 'outlined a wish for 250 Red Beards for RAF use, to supplement 400 one-megaton weapons in a counterforce offensive against the Soviet bomber force'. With just 144 skybolts ordered it seems impossible to justify a force of more than 72 from the mid 60s onwards (The various V-cruisers proposed, with as many as 6 skybolts, look like expensive vulnerable baskets with many eggs).

Initial V-Bomber numbers were 250, though I dont know when the switch to 240 occurred yet. In August 1957 the 184 number was scaled down to 144 (with 104 Mk2s). That became the baseline number for the Skybolt order which further scaled the planned fleet to 72 Vulcan B.2s with Blue Steel Victors providing an interim capability prior to completion of the Skybolt procurement and Vulcan modification*

Interesting fact directly related to the actual topic of this thread; at the meeting that decided to proceed with the B.2 Victor and Vulcan it was also decided to remove the Olympus from the military programme and focus on the Conway, Olympus was only restored after Bristol Siddeley offered to absorb a considerable amount of the cost.

One is left wondering how far a Vulcan Phase 3 with Conway's would have flown....

The removal of the Olympus from the military programme in 1956 would have also kept it out of the TSR-2 making either the Medway or the Conway (Turbofan either way) the only realistic choice.

*Interestingly the planning figure for Blue Streak deployment seems to have been 100, meaning that total nuclear force planning was still for roughly 240 warheads through to at least 1959, it should be noted that the Deputy Chief of the Air Staff was scheming 140+ as of 1958. The scaling down to 60 Blue Streaks apparently coming later.
Richard Moore 'The Royal Navy and Nuclear Weapons' pg.105

sealordlawrence said:

Intriguing, I am seperated from my copy of Jet Bombers for the next 2.5 weeks or so, thus I will have to wait to re-read that section.

As for V-Bomber commitment, I have a litany of internal debates in the war office and elsewhere about actually how useful the V-Force would be both as an actual nuclear delivery system and whether it served any political purpose, and I assume that these were contributed to by the relatively poor performance of Avro and Handley Page in terms of product delivery. I have the first Valiants (25) being ordered in April 1951, with Vulcans and Victors following. A lack of commitment prior to 52 would fit with the internal debate that was ongoing about the utility or otherwise of the force.

Force planning, as I understand it, was 240 until late 1955, then 200 until August 1956, then 184. I dont know how long that one lasted though the force peaked at 159 in 1964 just as it was discovered that Valiants had an unfortunate tendency to fall apart. I am not aware of a larger number than 240 but equally I have no notes on this topic until about 1954 so it is plausible that earlier numbers were larger. I have a recollection of the RAF wanting 300 strategic warheads though I can not remember the source and I would not vouch for it without seeing it again. With just 144 skybolts ordered it seems impossible to justify a force of more than 72 from the mid 60s onwards (The various V-cruisers proposed, with as many as 6 skybolts, look like expensive vulnerable baskets with many eggs).

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Hi Folks,
Did Bristol hold back on turbofans because of the Orion turbo-prop,
it had twice the output of the Tyne and would have pulled the wings of the Britannia.
With the thin wing might have been useful, Just a thought the Orion would have been ideal for the Rotodyne.
The V1000 wing wes evolved from the Valiant B2 wing and have heard that it was super critical in all but name so that with a Big pair of Bristols at 40,000lb each would have been a World Beater.


Merry Xmas

Bristol BE.58 Mock-up and data from the 1959 Farnborough Air show:

Source: http://www.flightglobal.com/pdfarchive/view/1959/1959%20-%202233.html

You will find plenty about the Orion over in this thread.
Bristol, in the fifties, had a large amount of NATO and other military project work plus a hard time with the Britannia
Bristol started looking at the turbofan and civil market with a scheme taking the BE.53 and de-trousering it to turn it into a straight turbofan. It was a project only and would have been in the Medway area at a static thrust 14,500 lb. of but started the dialogue with the aircraft designers. It soon emerged that a smaller engine was called for and as B and AS technology came together it designed a new hp spool and in 1962 this first ran as the core of the BS.75- the first new BS engine, delivering 7,750 static thrust for a weight of 1,610 lbs. Using the aerodynamics of the Olympus 301 and Pegasus LP compressors the BS.75 has a 3 stage fan with a 1.85 PR. The entirely new 10-stage hp compressor has the igv and first stage vane variable feeding into an annular combustion chamber containing 16 hockey stick vapourisers. Each compressor is driven by a two stage turbine that draws on the Proteus designs. First run of the new engine was Feb 6th 1962. There were other versions planned such as the BS94 lift engine with four swivel nozzles that eventually informed the VAK191 programme and was melded into the RB193 engine project.
The BS75 was initially specified for early schemes of the Fokker Fellowship but as the project grew it was equipped with 2 RB 183 Spey Juniors, lightweighted and simplified Speys. Initially each delivered 8,740 lb static thrust for a weight of 2,025lb.. the Spey Junior was uprated and eventually redesigned using RB211 technology and became the Tay.
A video of BS.75 on testbed is here; and a FlightGlobal cutaway is below:

As BS were making little progress in the civil marketplace with the BS75 they looked around for other ways of opening it up.... Meanwhile SNECMA were happily using their government's money in 'doing cooperation' ...they did two forays in the sixties which were just that.... forays.
In '64 they announced the M45 Mars engine as the basis for a family of smallish engines. Also Germany were looking at the VFW614. BS joined in January '65 to do the HP spool and combustion chamber. Thus the project became the first engine to be designed in two
The German government were building an aero technology base and so looked on the VFW project as a technical learning and manufacturing capability building programme; they put 50% of M45H funding into the Bristol Engines Division transferring 50m DM to BED's account in the early part of 1968.
BED had based the hp spool on the earlier scheme BS116 which was an excercise to produce a small engine with an aerodynamically scaled Olympus 320 hp system. As we found out on may a collaborative venture with the French... there was a long time element to be factored in plus the German aviation industry's optimistic forecasts.. so though the datasheet below gives target dates based on the actual first run.. the targets slipped badly so first flight was in July 1971 Type Test certificate for both aircraft and engine was not till 1974. SNECMA lost interest and so manufacture and development of engine switched to RR Ansty, where the Dowty variable pitch fan was tested. This was the M45SD-02 or RB410 engine.
The Germans eventually abandoned the VFW614 and so Ansty just supported those engines out in the field.

I've had the privilege of hearing and seeing the last VFW-614 (DLR's ATTAS test bed) doing flybys on a daily basis in 2006 - can't say there was anything particularly spectacular about it, but I did appreciate the rarity of it!
What's the deal with the annular splitter in the bypass duct on the RB410?

It is a big fan engine like the RB211, CF6, JT9D and so the bottom 10% of fan blade 'supercharges the flow into the IP/HP compressor... the S duct between is to get the hub/tip ratio right at entry to the faster moving spool.
This article in Flight 19 April 1973 is a good one as it explains the rationale behind the v-p fan.
The RB.410 finally ran in 1975 as part of a demonstrator programme for noise reduction.It delivered a thrust of 10,072 lb at a BPR of 8.73:1

Whilst all this was going on RR Bristol was thinking about a Viper replacement and the RB401-06 technology demonstrator was started and first ran in Dec 1975. The results from the two demonstrators built and tested were fed into the RB401-07 prototype engine design started in March 1976 and two engines were built and tested ... The -07 is slightly larger than the -06 which was 5,100-5,500 lbt range.... delivering 6,100 lbt.
The -06 also was used as a technology demonstrator for the RB 432 engine which was a Spey replacement design.
A really well illustrated article was published in the Sept 8th 1979 Flight; shortly after the engine was put on the 'back burner.'

Trident,
The annular splitter if I understand you correctly, is an annular gap uncovered when the fan is in reverse thrust mode....to enable the hp compressor to receive a supply of air to keep it running... amazing what consequences come from a variable pitch design.

As an aside I have written a thought piece on the origins of bypass here. It is interesting to see one of the earliest design had a gearbox like the RB410!

The M45 was an interesting parallel to the GE1 common-core approach, with civil high-bypass, military (M45G for AFVG), and turboshaft (Westland tilt-rotors). The result being one application, on the horrible VFW 614... I remember being on a demo flight over Colmar, in a window seat next to the engine, with the VFW-Fokker hoaxman next to me screaming in my ear "THE PRODUCTION VERSION WILL BE QUIETER!"

Speaking of Fokker, they kept hoping through the 1970s that RR would do the 432 or something similar, but by the time the Tay came along the Dutch disease was setting in and it was pretty much all over for the little Fokkers.

Meanwhile RR and UKG spent money on the RB.203 Trent, the RB.401 and the variable-pitch fan (which was supposed to power the new generation of QSTOLs), none of which went anywhere at all.

I thought, that through a very long and torturous process the the RB.401 was sidelined for the 432 (which used the same tech) which slowly morphed into, via Japanese Aero-Engines for a period in the 80s, the IAE V2500?

You are right ... the RB401 did get 'reprioritised' as a technology demonstrator for the RB432 which as you say went East then retuened as a pan European project. During my 15 years at Derby I was involved in some of the earlier attempts at collaborative ventures both cross-channel and cross-pond.. it was national politics that killed them rather than technology... also RR and Bristol and the other bits were trying hard to form a clear strategy which then got undermined by a change of government or congressional protectiveness... an interesting time!!

tartle said:

It is a big fan engine like the RB211, CF6, JT9D and so the bottom 10% of fan blade 'supercharges the flow into the IP/HP compressor... the S duct between is to get the hub/tip ratio right at entry to the faster moving spool.
This article in Flight 19 April 1973 is a good one as it explains the rationale behind the v-p fan.
The RB.410 finally ran in 1975 as part of a demonstrator programme for noise reduction.It delivered a thrust of 10,072 lb at a BPR of 8.73:1

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tartle said:

Trident,
The annular splitter if I understand you correctly, is an annular gap uncovered when the fan is in reverse thrust mode....to enable the hp compressor to receive a supply of air to keep it running... amazing what consequences come from a variable pitch design.

As an aside I have written a thought piece on the origins of bypass here. It is interesting to see one of the earliest design had a gearbox like the RB410!

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Not quite, although the auxilliary intake for the HP compressor is interesting - thanks for pointing it out, I missed that! I've outlined the various features discussed using different colours in the attached image, what I was wondering about is the red thing which seems to split the bypass duct into inner and outer parts!

Aha!.....acoustic lining! I am not sure that this was fitted in actual acoustic performance testing... still checking.

Why VFW-614; why M.45H?

US had funded a phoenix FRG Aero industry from 1956, to spread the burden of defending N.Europe. By 1961 licences had restored production capability, but R&D had not matched that. FRG Govt. looked for niches not dominated by their licencees, and came up with V/STOL (which also offered military logic - vulnerability of runways close to Red mass). RR was funded - in part by FRG - to pursue Griffth's (deadweight) liftjets; BSEL was funded to work with its (Noratlas)Hercules licencee (M.A.N, soon MTU) on Pegasus for Do.31. Until Healey chopped well, early-1965, BSEL was the heftier UK aero-engineer, working (66.6%) with SNECMA on B.Ol.593. On 17/5/65 UK Minister of Defence Healey chose Jaguar+AFVG; MoA technical staff, on the back of an envelope, carved up workshare, as RR lead Turbomeca on Jaguar engine, so SNECMA lead BSEL on AFVG; airframes, recip: BAC junior on Jag, senior on AFVG. No techno-logic pretended or attempted, else HSAL, not BAC would have been given the swinger (AWA and Folland had long toyed with pivots; BAC, nay, even the Main Board of Vickers, had seen no future in Wallis' notions). So, that put HSAL in pole for a Euro civil wide-body, soon funded into Feasilibility Study. HSAL teamed with Breguet; BAC, naturally, with SST partner Sud. FRG Govt. wanted a slice of this.

FRG had entered civil aero on niche No.1, bizjet. Can do better, they said, than Sabreliner and Jetstar. So HFB tried, chose the USP of forward sweep...and later found why others had not done that. Then on niche No.2, jet Friendship: why leave that to little Fokker, they said, and chose the USP of over-wing engines...and later &tc. But that work-in-progress gave HFB+VFW a (slim) pedigree, to join HBN-100 (N= FRG Nord Gruppe, HFB+VFW {as well as France's Nord Avn.}). FRG laboured at that time under a commitment to offset DM:£ pain incurred by UK Forces defending W.Germany (and UK). There was a limit to how many Skeeters, Sycamores, Gannets and other turkeys she could impose on her fighting men. A cash contribution to UK R&D met the political need and secured techno-transfer if UK had anything to transfer. Such as on hot turbines. An engine was needed for VFW-614. RR was brewing one for Fokker (to be RB183/F-100), so: Q: what's our old mate BSEL got? Well, nothing...but BSEL's mate SNECMA invented a civil derivative of its front end of M.45G. Overnight. Making all FRG's political mates happy.

9/10/66 RR bought BSEL; 29/6/67 Dassault caused demise of AFVG/M.45G. M.45H was orphaned...but FRG chose to persevere with it and VFW-614 as its pedigree in worksharing negotiations on the Big Twin. (and FRG retained a full share of A300B and all later family models...even though most work went to not-VFW).

alertkin,
That seems to ring true! The path of development of engines at Derby seems much more logical than that followed at Bristol. Even the Derby technology that went into VTOL was used in civil projects as well as military; these days with a shortage of technical skills in UK the transfer and buildup of knowledge in Germany is useful in today's RR projects; makes you wonder if the disruption at Bristol caused by Fedden's departure echoed through the years.

AK - What my boss Mike Ramsden used to call the "Buggins' turn next" theory of program allocation. Accordingly, too, HSA got the trainer.

Of course, one reason for the overwing engines on the 614 was to put the floor of the swing-nose freighter version at truck-bed height :-[ . Hope that it works out better for the HondaJet.

Thought this might be of interest: It is a business led look at RR and RB 211.

Thank you for link (which traces "ownership", "role of professional engineers" and "success", largely defined as share price; the paper explores whether "managers" or "shareholders" have greater influence on "success").

Quite correctly the paper addresses senior staff, the movers and shakers. Lombard, Hooker are noted (just as in previous decades, Hives was). It then goes into the structures by which acquisitions and R&D projects were funded, to discuss whether "engineers" or financial engineers (Sir John Rose) have more impact on business fortunes.

The A of course is that it all depends. Financial wizards need a sellable product invented by engineer wizards (3 shafts is here seen as key to RB211/Trent's distinction in, at market, matching CF6 and defeating JT9D). Neither "succeeds" isolated from the other.

The colossal Maguffin* here is that I don't think anyone realized before the launch of the 777 (at least not at decision-making levels) how the three-shaft engine could provide better growth potential than a two-shaft design, without going to a new centerline - due to less torque on the LP shaft because it only carried the fan load, the IP section running faster/more efficiently than a compressor-turbine set constrained by fan rpm, and the HP spool being limited mostly by temperatures and just taking on more and more as materials improved.

Nor did anyone see the aerodynamic goodness of the Hyfil fan being replicated in SPF/DB titanium, which was the other part of the RR secret sauce. Fascinating story overall...


*Defined as the seemingly accidental thing that drives the plot, like the British police in Day of the Jackal who break the case by hunting the wrong man.

The amazing thing is that I was involved in the early thinking on an all-metal no clapper fan blade... not my ideas but I spent many weeks at my drawing board looking at how to do a solid leading edge honeycombed blade that would overcome the shaving brush characteristic (after bird strike) of the Hyfil material. This was in 1968! The thinking continued and eventually diffusion bonding of titanium came on our radar ... and the rest is history. BBC4 did a programme on how today's blading is made.
In 1974 we had enough operating data on all 3 engines to know the 3-shaft system was a winner. The overall stiffness meant that turbine tip clearances did not increase much over time ... if I remember correctly you would only have to turn the wick up a couple of degrees C to restore take off thrust after a year's operations. ... CF6 was 10 degrees (whippy shafts).. why does this matter... it affects the metal temp of turbine blades... and the creep life is halved or doubled with a 9 deg change in average blade cross-sectional temperature!
This is one description of the challenges of making them!
By the time the 777 came along the technical guys had risen high enough to affect strategy!

In the early-1970s sales battles: on DC-10 v.L.1011: only Northwest and JAL took DC-10/40/Pratt for commonality with 747; DC-10/10/CF6 competed v.L.1011-1/100/RB211-22B, where long term performance retention could not yet be claimed as an RR + because it had not yet emerged. Instead the engine kept falling off the wing. Cathay thrice deferred their first 1,000 hr. party. What could be measured was weight: RB211 was heavier. Not good on short/medium haul.

On DC-10/30/CF-6-50 v. L.1011-200/500/RB211-524B4 efficiency over longer cruise put RR ahead: it was airframe price/delivery that caused MacDoug to take more orders than Lockheed.

On 747-200B, then -400 the performance retention issue won sales, despite Pratt/GE earlier certfication on type. There was a window, sort of 1984-87, when only RB211-524D4 could offer ultra-long haul, giving Cathay/Qantas/BA a couple of seasons non-stop LHR-SIN/HKG, upsetting Singapore Airlines something rotten. Then CF-6/80 caught up. It was thereabouts that Pratt slipped. GE won at least one Pacific order (ANA, on 747-400 jilting their TriStar partner) by spreading alarm and despondency over RR's business survival during that 1980s' period when nobody sold anything to anybody (Cathay's order of 1 747 on, ah, favourable terms, brought a year's total {was it 1984-ish?} to 6 deliveries, Boeing's minimum to sustain the line). If you had sectors of 16hr+, buy Rolls; if you interspersed long with medium haul, lighter GE made sense on fuel. On maintenance/ reliability each of the three was better this year, worse next, all in rotation.

Interesting stuff! [not sure what it has to do with BS turbofans.maybe we should move last couple or three posts to 'The Big Fan Club' or something?] Anyway you awaken memories of the work we did in 1976/77? on first the RB211-535 for the 757; to be followed immediately by the work on -524 for long range 747, I think. These were a step change in time to test for Rolls and knocked a year off the time to market! and involved long hours in the office!

At one point (around 1976) Macs did try quite seriously to sell DC-10-50 with -524s to BA, but BA stuck with TriStar 500 - shorter and fewer seats and rather quickly replaced and pensioned off to the RAF.

At that time, RR certainly seemed to be a Johnny-come-lately to the 747 market (well, which of us was thinking that they'd still be building them in 2012?) and a lot of customers seemed to be buying on performance as much as SFC or retention. The JT9D-7Q was dominant in the late 1970s for this reason.

http://www.flightglobal.com/pdfarchive/view/1979/1979%20-%200168.html

Yes... it was getting lead engine status on the 757 that began to change the flow ( of orders). As a young engineer it was certainly my understanding that we had to break into the markets 'owned' by P&W and GE, or become a smaller national military engine supplier; we also knew by then that the configuration of the 3-shaft engine made that more likely as we had a configuration that gave us scope for 'playing' with engine sizes and that its robustness was the key to reliability; the modular concept also made maintainability the key to keeping the airliners in the air and allowed us to think about selling operating hours per dollar. The flow of life data coming back was analysed by statistical techniques and we could pick out the effect of modifications very early on and would know whether we had a great fix or merely a good one which enables development effort to be focussed on the 'big' issues.... but it is a long game.... as someone just said on Radio 4's 'start the week' it is more 'Mo' than 'Bolt'. But it paid off... so I have always been pleased by the outcome not surprised though. The rise in fuel costs makes a difference too!
Strategy plus Engineering!

Trident said:

I've had the privilege of hearing and seeing the last VFW-614 (DLR's ATTAS test bed) doing flybys on a daily basis in 2006 - can't say there was anything particularly spectacular about it, but I did appreciate the rarity of it!

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A picture of the ATTAS test bed... to better appreciate how spectacular a sight it must be!

Here are details on the BS143 2 shaft Pegasus-based engine configuration for Tornado.

http://jim-quinn8.blogspot.ca/2012_03_01_archive.html

CharleyBarley... excellent link. The enabling power of computers writ large! Just shows how the rise of the computer from Lyon's coffee house to the ubiquity of Costa can change what we can achieve.. what Michael Schrage calls 'iterative capital' -the number of times we can cycle through a 'protyping' phase in a given time period opens up options for us to debate how to use.