Rolls-Royce Griffon and Eagle engines

Was there ever any use for the 2-stroke Crecy envisaged?

The original RAF requirement for the Wyvern was as a piston engined strike aircraft (similar spec to Bristol Brigand) to be powered by the Eagle.
The navy wanted turboprop, but even that was after in changed its mind about the initial Eagle powered Wyvern TF.1 – hence really dragged out development.

It is worth remembering, that the increase in the Merlin’s power, was almost exclusively due to a better understanding in supercharger technology, (that and the introduction of 100 octane, and then 150 octane fuel); by the time that the Eagle was under development, blower design was pretty much at its zenith (had to use that word, as the letter “z” has all but seized up), consequently, the jump in horsepower, seen early on in the war, could not have occurred.

I believe that Hives (at RollsRoyce), was at a loss (initially) to understand Stanley Hookers enthusiasm for the Whittle engine, Hooker showed him the figures for the Whittle engine, (at that time giving 1000 lb of thrust); ” that doesn’t sound much” said Hives, Hooker then went on to say, that assuming 70% propellor efficiency, this was roughly equal to a Spitfires Merlin, at full throttle, Hives imediately summoned his secretary, and told her his proposed visit to Lutterworth, August 1940.

The only stated application I have is the Wyvern. I think that the Eagle was an engine very much out of tune with the times. It seemed destined for failure.
Too big, too heavy, too complicated and too expensive.

The Eagle was fitted to the Westland Wyvern.

Yes, but only as a test powerplant until turboprops came along. What did the designers at Rolls-Royce plan to fit the Eagle into?

Also, although Robert Hilton correctly states a power output of the Griffon as 2500 hp, this was only correct for certain given marks. Some 60 series engines were quoted as having an output of 2350 hp, while the 58 had a maximum of 2490 hp.

I only quoted the highest rating for the Griffon, like the Merlin it had a fair number of power ratings. I’m also quite wary of stated ratings as they are often influenced by all manner of factors such as altitude and octane rating etc. They were meant to be general, not gospel.

Oh, I wasn’t aware of that. I guess you’re right, though what it would have been capable of if fully developed is still a matter of speculation and would the fully developed Sabre still have outdone it?

I think it might have been interesting to see what the Eagle could have produced if fully developed. The chances are that it would have broken the 4000hp barrier if the way the Merlin and Griffon were developed is any guide. The Merlin starteed out sub 1000hp and ended up at the bottom end of the Griffon power scale. The Griffon started at 1700+ and went up to nearly 2500. On that basis I would certainly expect to see 4000+ from a fully developed Eagle.

The Sabre was at 4000+hp in experimental form at the same time , so the Eagle should have produced a lot more for the extra 10 ltrs

Comparing like for like, H24 layout twin cranks, the Eagle v Sabre the Eagle is heavy 3900 v 2300 lb , same power 3500 hp but Sabre 36 ltrs (same as Griffon) v Eagle 46ltrs. So why didn’t they use the sabre in the Wyvern ?

I would have said that the Eagle engine was that much heavier because it had almost double of everything that the Griffon had. 3,900 Ib was its dry weight.
I’m guessing that had the Eagle been adopted and developed that it probably would have achieved for more power in later versions, look at how much the Griffon power increased over its production run, starting at 1,730hp to at least 2,455hp on the Shackleton Mk.3

Be very careful when quoting Wikipedia, it can be unreliable. For instance your quote above is from Wiki which also states the Shack Griffon 57s were of 1,960hp, they were actually almost 500hp more powerful at 2,450hp – even on the earlier marks.

I think it might have been interesting to see what the Eagle could have produced if fully developed. The chances are that it would have broken the 4000hp barrier if the way the Merlin and Griffon were developed is any guide. The Merlin starteed out sub 1000hp and ended up at the bottom end of the Griffon power scale. The Griffon started at 1700+ and went up to nearly 2500. On that basis I would certainly expect to see 4000+ from a fully developed Eagle.

Thanks everyone, loads of info!

It’s interesting to note that while engine power went up and up throughout the course of the war the power:weight ratio didn’t really increase all that much. Is that right? At least until the Crecy was built … does anyone have more details than Wikipedia on the Crecy engine? I know they had a prototype built and running but it didn’t seem to produce as much power as you would expect from a 2-stroke.

The other thing I was wondering is since the Eagle was so enourmous and heavy, what was it supposed to fit into? Were they planning on shoehorning it into a Spitfire/Spiteful for example? Or was it intended only for new aircraft, e.g.

Thanks for clearing that up…..I’ve obviously got a bit muddled there. It still wasn’t MOD procurement’s finest hour though! 😀

I love the Shackleton…..I’m just glad the RAF never had to go to war in them.

Bit of a myth re the AN/APS-20 radar, it wasn’t the same scanners passed down the line, and the FAA Avengers didn’t have it anyway (mixed up with ASV-13 on Avengers AS perhaps?).
Although the -20Fs fitted to FAA Gannet AEW.3s were litrally removed and fitted complete with the same radomes to the RAF Shackleton AEW.2s, they are not exactly the same model fitted to earlier FAA Skyraider AEW.1s.

The Griffon remained in British front line service for something like 50 years, finally being withdrawn with the Shackleton AEW II in 1991. Is this a record?

Almost certainly a record, sadly not due to the undoubted excellence of the Griffon but rather to the unmitigated disaster that is MOD procurement! I think the radar carried by the Shakleton AEW also deserves a mention; wasn’t it fitted second-hand out of an ex-FAA Avenger and also about 50 years old?

Doug97,

Wik is correct in the given displacement of the Rolls Royce Griffon engine as 2239 Cubic Inches Displacement (CID), which converts to 36.7 litres.

The weight you quote, however, is actually quite variable. For instance, the single-stage, two speed 57, 57A and 58 will weigh considerably less than the two-stage, two-speed, intercooled 60 series. (sorry, exact figures not to hand here in my office, so everything here is from an ageing memory)

Also, although Robert Hilton correctly states a power output of the Griffon as 2500 hp, this was only correct for certain given marks. Some 60 series engines were quoted as having an output of 2350 hp, while the 58 had a maximum of 2490 hp.

The devil being in the detail, the 2350 hp output of the 60 series was at full throttle height with full-speed supercharger (also known as high gear) at high altitude in, for example, Mk XIV Spitfires, while the 2490 hp 58 was at full throttle height in high gear with supplemented water-methanol injection.

Full throttle height in high gear with water meth for the 58 was…..only 3000 ft, the 58 being designed as an ‘LF’ or, low altitude engine. The 60 series were ‘HF’ or high altitude engines.

History Lesson

The Griffon was the last in a long, illustrious line of great Rolls-Royce engines sharing the same displacement that started with the Buzzard (2239 CID), and included the ‘R’ (2239 CID) as installed in the Supermarine S6B. The Griffon was designed before the PV12 (later to become the Merlin – the first engine that almost broke Rolls-Royce) and ran before the Merlin. However, in the mid ’30’s, demand for a 1000 hp engine exceeded demand for another 2000 hp engine (Rolls-Royce were heavy into the Vulture – the second engine that almost broke Rolls-Royce), and the Griffon was set aside for a while. Jeffrey Quill’s blowing the doors off the captured FW 190 while flying the Mk XII Spitfire in front of various officials changed that rather quickly. (This episode also injected new life into the Spitfire, which said officials had considered past its prime.)

The Griffon remained in British front line service for something like 50 years, finally being withdrawn with the Shackleton AEW II in 1991. Is this a record? It is still serving with Her Majesty’s Royal Air Force 75 years after its initial design, modified to RG30SM-S configuration in the Spitfire Mk XIX’s of the BBMF. Is this a record?

The third engine that finally did break Rolls-Royce, albeit in 1971, was the RB211, an engine widely regarded as one of the finest aeroengines ever produced, and so successful that it is still going strong as the Trent series. A few years ago, one RB211 engine had remained on-wing for over seven years and 30,000 hours. This may be a record that will prove hard to beat.

camlobe

I would have said that the Eagle engine was that much heavier because it had almost double of everything that the Griffon had. 3,900 Ib was its dry weight.
I’m guessing that had the Eagle been adopted and developed that it probably would have achieved for more power in later versions, look at how much the Griffon power increased over its production run, starting at 1,730hp to at least 2,455hp on the Shackleton Mk.3

Be very careful when quoting Wikipedia, it can be unreliable. For instance your quote above is from Wiki which also states the Shack Griffon 57s were of 1,960hp, they were actually almost 500hp more powerful at 2,450hp – even on the earlier marks.

The Eagle had two crankshafts also – which aren´t the lightest things in the world.

It may also depend on whether it was a `bare` engine,or whether it was `equipped`,ie ready to install as a unit,including mounting,,.

The Griffon was 36 litre and the Eagle was 46. The Eagle was also a 24 cylinder engine as opposed to 12 for the Griffon. It also produced some 3,500 hp compared to 2,500 hp for the Griffon.
The Eagle was fitted to the Westland Wyvern.