Fairey aero engines - any good info?

A specification for the Fairey P.24 "prince" engine gave power as:
For 87 octane fuel ("power curve 1393"):
1,500hp @ 12,000ft and 2,600rpm (normal)
1,600hp @ 15,000ft and 3,000rpm (maximum)

For 87/100 octane fuel ("power curve 2604"):
1,760hp @ 12,000ft and 2,600rpm (normal)
1,900hp @ 15,000ft and 3,000rpm (maximum)

Also, the intake arrangements were as discussed above - the supercharger discharges into a pipe which has 4 outlets that feed into galleries cast into the crankcase, then from there through galleries cast in the side of the engine blocks and into the head.

A memo, dated 11 February 1942, by the Airscrew Panel of the Aerodynamics Sub-Committee says that the P.24 was able to produce the following during testing in the 24' wind tunnel:
1,570hp @ 2,400rpm
1,618hp @ 2,600rpm
1,652hp @ 2,800rpm
1,680hp @ 3,000rpm

This is at the rated altitude of 10,000ft.

It was suggested that 1,800hp may be obtained at 3,000rpm if the supercharger drive ratio was lowered.

The airscrews (Fairey design and manufacture) and engine were cleared for 3,200rpm in a dive.

Here's an image of the Prince-powered Fairey Battle.

James W. said:

Fairey was not on the 'approved' MAP/Air Min list of engine makers.
& frankly, with those outputs from 51litres, the P.24 was never likely to get a production contract.

The Sabre-powered Battle test machine was a much livelier bird..

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I think that a Merlin 60-series Battle would probably be livelier too.

And we're going off thread again

Airframe makers were a lot more interested in power to weight and power to external volume/shape than they were in power to displacement ratios.
In fact power per cubic inch or per liter might not even show up on list of attributes an airframe maker might have when looking for engines for a new project.

Fairey had no engine production facilities. Or perhaps no more than an an experimental workshop. The 50 Fairey Felix engines that Fairey had sold to the RAF had been imported from the US. This may have some bearing on the air ministry's view of the newer Fairey engines. Fairey needing to create a production facility from scratch or licence production to another company. Either path might involve delays/problems the Air ministry might not want to get into.

Shortround6 said:

Airframe makers were a lot more interested in power to weight and power to external volume/shape than they were in power to displacement ratios.
In fact power per cubic inch or per liter might not even show up on list of attributes an airframe maker might have when looking for engines for a new project.

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In those metrics the P.24 doesn't look too brilliant. Quite large in frontal area, quite heavy for the power.

The RAE's interest seems to be centred largely around the contra-rotating props.

As you noted, Fairey didn't have their own production facilities, which would make getting the engine into production unlikely.

Also, earlier in the thread there was discussion about three engines - the Prince V12, the Prince H16 and the Monarch H24. The documents I have refer to the P.24 as the Prince.

Personally, I don't think the H-16 was never built and may never have even existed as a design. Fairey built the normally aspirated "Prince" and the supercharged "Super Prince" (or Prince II). The P.24 is often mistaken for a H-16 because there are only 16 exhaust stacks (each of the two middle stacks on each bank are shared by two cylinders). Also, the P.24 was originally called the Prince (hence the "P" in "P.24") because none of the other "Princes" went into production.

fubar57 said:

View attachment 348144

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Yes, nuuumannn posted that information on page 1 of this thread.

Yep!

Some more info on the Fairey P.24:

April 1941 the Ministry for Aircraft Production send a message to the British Air Commission in Washington DC that the Fairey P.24 engine will not be considered for production in the UK, stating that:
"We have had reluctantly to abandon further development and production planning for need to concentrate on other types already more established and with greater facilities, e.g., Rolls-Royce, Sabre and Bristol. Substantial further development remains to be done to achieve type test rating at power to compete with Vulture and Sabre".

Ironic, since the Vulture was canned by then, or was soon to be.

It further goes on to suggest that the design and concept may be attractive to American firms and that Forsyth and some staff should proceed to the US.


In December of that year the decision is reaffirmed:
"Dear Henry [Self of British Air Commission in the US],
You may wish to know that V.C.A.S. [Vice-Chief of the Air Staff, Sir Wilfred Freeman] in a letter which I have just received informs me that the Air Staff are definitely not interested in the P.24 engine."

In June 1941 the BAC sends a letter to the MAP regarding the P.24 and interest in the US.

It states that General Arnold and General Brett are said to have been interested in the P.24 project after seeing a demonstration. But "in discussion Fairey pointed out that considerable amount of development would be necessary before engine would be ready for production".

General Brett stated that he intended to discuss the possible development of the P.24 with the USAAC Materiel Division and requested to following information:

• General statement of technical particulars
• General arrangement of engine and propellers
• Particulars of bench and flight tests
• Pilots' reports, particularly in reference to vibration and effect on control, manoeuvrability
• Installation drawings
• Photographs

In July 1941 the MAP informs the BAC that Forsyth is scheduled to travel to the US with the plans of the Fairy P.24 engine in mid July. He is to travel on a (presumably RAF) Liberator.


In November if 1941, via the British Air Commission, Richard Fairey writes to MAP about the progress of the engine in the US.

He states that "negotiations in connection with the P.24 engine and propellers are proceeding satisfactorily", that "production features of the engine have been met with approval" and that "the Ford Company had shown considerable interest, and have indicated their willingness to produce the engine if the U.S. Air Corps agree".

He goes on to say that the USAAC wanted to begin flight trials with the engine, that Forsyth will assist with installation drawings and that Wright Field had already produced 3-view drawings of the installation in the P-47 and the A-25 (SB2C Helldiver). A flight engine is requested to be sent to the US.

January 1943, Fairey (via the BAC) requests Fairey (via the MAP) to produce a new set of propellers for the P.24 installed in a P-47.

They gave the following information to enable Fairey to design the propellers:

• Gear Ratio: 0.543
• Diameter: 11'-6", maximum 12'-6"
• Estimated Speed: 335mph @ 9,500ft, engine rpm 3,000.
• Power Output: initial tests to be done with 8:1 supercharger gear ratios at the given rating, later tests to be done at 1,800hp @ 3,000rpm @ 10,000ft.

Plus they suggest that the maximum pitch settings for the prop should be 2° beyond the pitch required for 335mph.

The list of items requested are:

• Six propeller blades complete with sockets
• Front Gearbox
• Rear Gearbox
• Six cross shafts, complete with ball races and gears [for superchargers? It isn't clear]
• Set of hub bearings
• Spare oil seals for hubs and blade roots
• Spare motor
• Spare solenoid switch

Interesting to me that the estimated speed for the P-47 would be approximately 335mph at 9,500ft, when the XP-47B had tested faster than that nearly a year before (344mph @ 5,425ft and 382mph @ 15,600ft) and teh production P-47s were better still.

Also of interest is that the initial tests would be at the engine's (then) current rating and later to be at the higher power of 1,800hp. It doesn't say directly, but I suspect the high speed estimate was for the latter power rating.

Already in May 1941 the British Air Commission is expressing doubts as to the possibility of the US undertaking production of the P.24, stating the following reasons:

• As per the Ministry for Aircraft Production, the US had expressed a similar desire to concentrate on established types, where "productive capacity is in existence or being located".
• Many new engine types were under development in the US and introduction of another new type would effect the development of those engines
• With the state of development of the P.24 it was not expected that the engine would reach production to be useful for the war effort. Fairey concurs with this.

The possibility of interest by the US administration or private concerns would be investigated to see if "any are sufficiently promising to justify Forsyth's presence here".

A couple of letters/memos regarding the P.24.

Fairey P./24 Engine: Development Prospects.

D.E.P.2.

1. I was talking to Maurice Wright of Fairey's on 14.12.40. and he asked me what the prospects were for this engine. His contention was that either we should go ahead and find a niche for it, or else put it into cold storage. The question then would arise , what should Forsyth do? It would be no good his staying on if the main reason for his employment disappeared.

2. Wright also suggested the possibility of getting the Americans interested in the manufacture of this engine, in which case Forsyth might usefully go to U.S. I should like to put the question of the future of this engine to Sir Henry Tizard. Have you any recent appreciation of the position and its possibilities? If not, could you have a short note prepared to put to Sir Henry Tizard into the picture, sor that he can review the matter.

Roderic Hill
D.G.R.D.
17.12.40


The reply:

D.G.R.D.

This matter has already been put to Sir Henry Tizard as in my Minute, copy Enclosure 2A. 2B, copy of minute to P.S. to Minister also refers, relative to a letter addressed personally to the Minister by the Chief Draughtsman of the Fairey Engine Section.

Our agreement with Maurice Wright was that the engine should be put in cold storage for the reasons that
(a) very considerable additional development for which the firm have no facilities will be needed to bring the engine up to an output appropriate to any of our requirements,
(b) there are no production facilities available for it.

I have given much thought to the possible employment of Captain Forsyth with respect, for example, to the production supervision of engine power eggs. His temperament, however, is difficult, and the engine firms would certainly not respond happily to an association with him, involving his full admission to their own engine and power egg developments [OUCH!].

In his natural enthusiasm for his own engine he has been led, unfortunately, to overstate his claims for the present state of its development, claiming powers which have been only obtained by snap readings and associated with a variety of failures.

D.E.P.&D
22.12.40

P.S. To Minister [of Aircraft Production?] from G.P.Bulman, dated 19.12.1940 states:

"The decision [not to proceed with the P.24] was based on the fact that while the engine, in form, has many attractive features, much development would be needed to bring it up in output which would render it suitable for the R.A.F. purposes. even then no place for its production is available.

"Since the engine completed the 50 hours type test [British military ratings used a 114h type test IIRC] at a rating of 1275 b.h.p. with a maximum power of 1490, a number of short individual tests have been made, up to powers of 1750 b.h.p., but there have been no consistently long periods of running at the higher output owing to the series of troubles with the superchargers and main bearings, confirming our view that considerable development would be required to clear the higher power, the firm having inadequate facilities for such development.

"The running at 2,200 h.p. mentioned in the letter was confined to four readings of 2 mins. duration each at 1,100 h.p. output on half the engine only (the engine is in effect two separate motors in one carcass)."

The rated power of 1,275hp is approximately half way between the Merlin III at +9psi boost (1,250hp) and +12psi boost (1,300hp) at maximum power and rpm.

http://www.spitfireperformance.com/merlin3curve.jpg

The rated power of the P.24 was only 100-150hp more than the rated power of the Merlin XX, which was entering production and maximum power (per type test) was only 30hp more than the Merlin XX in FS gear with +14psi boost. in an engine that weighed 800-900lb more and had a considerably larger frontal area.

By the time it went into production it may well have had a maximum rating of ~1,800hp, but by that stage the Merlin 60-series was around and making the same numbers for at least a 500-600lb weight saving (the P.24 would, not doubt, have increased in weight in order to survive the type tests at the higher powers).

As for flash readings of 2,200hp, the Merlin II Special had already demonstrated the capability of the Merlin to survive at such power for short periods, recording 2,160hp at +27psi boost at sea level.

I have some other documents, one in which the benefits of the P.24 for the FAA are explained and a comparison between the P.24, the Sabre and the Merlin in terms of power output and power to weight, both with and without contra-props. I will try to post the claims tomorrow.

Thank you very much for the time and effort in making these posts, a simple click on buttons on the lower right doesn't seem to be enough.