Chicken and Egg, fighter airframes and engines.

[fliger747]

Were fighters developed to fit existing or developing engines or were engines developed to fit an airframe?

 

[tyrodtom]

I think it was usually aircraft designers fitting their creations to existing engines, or to engines in development.
Of course there's probably exceptions.

Most engines seem to take longer to develop than aircraft.

 

[Shortround6]

Were fighters developed to fit existing or developing engines or were engines developed to fit an airframe?

Usually the former.

Certain engines were developed to fit an idea or theory (P & W R-1535 radial was developed pretty much to suit the US navy demand for small diameter in order to improve forward view for example but it was used in a variety of Navy aircraft. Only a few Army experiments and only few (one?) commercial aircraft.

The RR Griffon was 'modified' to fit the Spitfire but that was much more arranging "accessories" like magnetos (a necessity) and starters, generator, pumps etc than altering the basic engine blocks/crankcase or configuration (no trying to make a 90 degree V angle for instance)

Like Tryodtom says, it took longer to develop engines than aircraft, one source says the Wright R-2600 was the fastest development of a US engine at 2 1/4 years for the early A version.

See http://www.enginehistory.org/References/WWIIEngProduction.pdf

page 14.

 

[wuzak]

Not many engines were used exclusively for fighters, and it hadn't been the intention for a few that were.

 

[GrauGeist]

A great many German designs languished for lack of the intended engine, too.
Some examples would be the He280 and Me262. The latter was supposed to be fitted with the lighter BMW 003 but in the end, only the He162 was operational with the 003.

 

[Deleted member 68059]

P47 is a good example of an engine "system" (which is to say engine and turbcharger) which were obviously designed in tandem for eachother. But this isnt really
the "engine" as such.

Five years was needed for a clean-sheet to production time for a completely new engine, by which time any airframe would be basically obsolete. These are
extreme examples, the Volksjaeger airframe went from concept to flight ready in about 9months, and the P51 in (aledgedly) 102 days... although its probable
that at least some preparatory work had been put in before as that was the date the contract was "signed", so I`d bet you could probably add a bit.

In reality due to the large disparity between airframe design timelines and the readiness of the engine (usually the aircraft designer had to design
around a "new" engine probably in very early prototype stages such that his plane might still be effective when it was ready in the future)
the engine choice sometimes changes, maybe several times. Often this engine turned out subsequently to not work properly when the
airframe was eventually ready....

Good examples of that being the Me109 and Hawker Typhoon. The Typhoon (actually started as the Tornado) was supposed to have the Vulture engine, then
the Sabre, but also the Centaurus was mooted for it too. All this mish-mash ended up as the Typhoon and Tempest. Sydney Camm certainly had
only a rough idea of which engine was going to be used, wasnt really his fault. I think the 109 went from Kestrel, to Jumo210, to DB601 to DB605
and even BMW801 (Me109X).

Later in the war FW put in loads of effort to explore various options for the 190D, and Jumo213 and DB603 were fully mocked up.

I`d say chaos was the usual order of the day regarding engine choice. The exceptions were very lucky airframe designers !

 

[Shortround6]

To further show the difference between engine development and Airframe, work on the R-2800 "started" in late 1936-early 1937 (one source says March) but Design work had been done on a 2600 cu in engine that got shelved when P & W found out about the Wright R-2600. Orders for forgings for the prototype R-2800 were placed March 21st 1937. Estimated power was 1650HP at 2500rpm. It took 3 years to get the production engine (1850hp A series engine) in March of 1940.

Snowygrouch is correct on the 109 but the 109 wasn't designed to use the Kestrel. The Kestrel was a hasty improvisation due to the lack of flight worthy Jumo 210s. Work on the Jumo 210 had started in 1931 with first engine run in 1932 but in the spring of 1935 the 109 (and other companies airframes) was ready to fly but the Jumo 210 wasn't.

I believe the Curtiss Hawk 75/81/87 may hold the record for most engines/power plants used in a single basic (but modified ) airframe. Curtiss trying two (?) of their own experimental 14 cylinder engines before giving up and using the Cyclone 9 in the prototype. Army went with the P & W R-1830 in the production P-36s, then we get into the Allisons (turbo in the P-37) and Merlin and???

It may have been economics too. The cost to develop and series produce an engine that is to be used in only one airframe may have been too great. The goal of any engine builder was to sell as many engines as possible for the least amount of R&D costs. They could spend a lot on R&D but then they wanted a large market share (if not dominate the market) so any design would not be tailored too closely to a particular airframe.

 

[fliger747]

Certainly the F4U was developed to use the new R2800, as was the late war F8F. However with the R2800 it is rather amazing to see the developed variations of this engine and it's evolution to power improved models of various aircraft. The F6F was designed for the R2600, but ended up using a R2800! As someone pointed out, such installations such as with the P-47 should rather be termed "power plant" rather than more simply the "engine".

Certainly in the tailoring of power plants to a specific aircraft and mission envelope was essential for optimal performance. Blower ratios, turbocharging, propeller selection and whatnot.

 

[wuzak]

Good examples of that being the Me109 and Hawker Typhoon. The Typhoon (actually started as the Tornado) was supposed to have the Vulture engine, then
the Sabre, but also the Centaurus was mooted for it too. All this mish-mash ended up as the Typhoon and Tempest. Sydney Camm certainly had
only a rough idea of which engine was going to be used, wasnt really his fault. I think the 109 went from Kestrel, to Jumo210, to DB601 to DB605
and even BMW801 (Me109X).

The Typhoon and Tornado were designed to use the Sabre and Vulture, respectively.

The Centaurus was adapted for the Tornado, not the Typhoon, later, after the troubles with the Vulture and it's cancellation.

There was no confusion for Camm - he knew what engine would be in the Tornado and Typhoon.

I believe both received production contracts.

 

[nuuumannn]

Although not about fighters, a good example of how engine development affects aircraft design is the German pre-war 'Bomber B' specification. The designs put forward were to have been powered by the Jumo 222 and DB 604. Of the aircraft that were actually built, the Ar 340 twin boom design never saw the light of day, the eventual 'winner', the Ju 288 V1 had BMW 801s instead of the company's own Ju 222, and the Fw 191, it was decided by the manufacturer would also have the BMW 801 owing to delays with the Jumo 222, although mock-up Jumos were fitted for inspection. The belated and unsuccessful Do 317 V1 was powered by two DB 603s. The entire saga is an example of wasted accumulated effort because of the failure of engines to perform as they were expected.

 

[swampyankee]

Engine development and airframe development were and, outside the military, are largely but not entirely independent. As an example, the R-2800's design started before that of any of the aircraft that would use it but it was incorporated into those designs before it was ready for service -- if you design an aircraft around engines that are already in service when the design is started, you'll end up with an aircraft no better than that of the competition. Usually, this worked. There have been a few engines that failed after aircraft were designed for them entered service(this was a common problem in US aircraft in the 1950s, e.g., everything that used the Westinghouse J-40). Other examples may include the British Manchester and the German He.177.

 

[nuuumannn]

Other examples may include the British Manchester and the German He.177.

The Manchester is always a difficult one to categorise, because yes, its powerplant was troublesome, but RR had largely eliminated its issues before the engine was canned. The Vulture was eventually cancelled as the Air Ministry wanted RR to (rightly) focus production on the Merlin. Handley Page avoided the issue entirely by designing the Vulture out of the HP.56 and responsoring it as the HP.57 Halifax with four Merlins, the first incarnations of which, the Merlin engined variety, being proof that even a good engine won't make a sow's purse out of a pig's ear.

 

[GrauGeist]

Another good example of the symbiotic relationship between aircraft design and engines, is the B-29.
While the airframe itself had several issues during development, it was the R-3350 that cause major delays and performance issues and there was no alternative at the time.
The in a twist of irony, the B-32 was designed as a "fall-back" for the B-29 in the event that it wasn't successful, but it relied on the very same R-3350 engines, which delayed it's entry into service even more than that of the B-29.

 

[Deleted member 68059]

The Typhoon and Tornado were designed to use the Sabre and Vulture, respectively.

The Centaurus was adapted for the Tornado, not the Typhoon, later, after the troubles with the Vulture and it's cancellation.

There was no confusion for Camm - he knew what engine would be in the Tornado and Typhoon.

I believe both received production contracts.

I`m afraid thats a bit of a simplistic way of describing the situation.

Initially because the Air Ministry didnt know what it wanted and nobody knew which engine would turn out to even work properly, Camm had to submit protoype proposals for both at once, the Air Ministry commissioned both to prototype stage, these were initially supposed to be on a completely COMMON airframe, however as time went on (still well before 1939) Camm found that the adaptation was so difficult that he ended up having to make each airframe so different that it actually ceased to be a common part at all, and his project ACTUALLY became two unique planes at that point where the fuselages ended up NOT being common anymore (which was not his original plan at all !)

The huge delay in delivery of the Typhoon was in large part due to the fact that Camms designers were still working on the Tornado in parallel to the Typhoon because nobody knew which engine would turn out to be any good, 500 of each were ordered, for what was now two totally different aircraft (again, Camm had intended originally to be a common fuselage !)

The Tornado wasnt cancelled until October 1941, and only then after the Vulture engine proved dissapointing.

You are quite wrong about the Centaurus timeline, (if I have understood your statement correctly?) which was first instructed to be investigated on 31st August 1938, nearly THREE years before the Vulture version (Tornado) was finally cancelled, the Centaurus version first ran in a plane in October 1941, i.e. it was already done when the Vulture version was cancelled. In other words the existence of the Centaurus version was basically independant of what was happening with the Vulture, Sir Henry Tizard championed the Centaurus version on 1st Jan 42, as he thought the Centaurus would be more useful in Camms fighter than in the two-engined Warwick, and there was a projected surplus of Centaurus engines, so the
original Ministry of Aircraft Production file says.

Of course Camm "knew" which engine was going into each version of his fighter, but the total chaos of nobody even knowing which of the three engines to choose actually by itself CREATED the three aircraft. Without that chaos there would never have even been a Tornado AND a Typhoon AND a Tempest (which was only supposed to be a slight upgrade of the Typhoon and ended up with two versions on its own as well!).

Utter chaos, it is misrepresentation of the history to make out the Camm sat down and decided to design all these planes - these choices were driven by a total lack of clarity of which engine to use for the "Camm fighter", as it was called in the early days.

Although the first version is always called the "Tornado", F18/37 wasnt actually named that until August 1939, the design work on the "Camm" fighter having started on 5th April 1937, i.e. nobody even knew was it was for the first two years...the naming of the other version as "Typhoon" happened in Dec 1939.

The level of confusion was so extreme, that the Air Ministry itself wrote to Camm asking him questions about the development milestones as they were trying to write a proper timeline!

 

[Ole Bill]

P47 is a good example of an engine "system" (which is to say engine and turbcharger) which were obviously designed in tandem for eachother. But this isnt really
the "engine" as such.

Five years was needed for a clean-sheet to production time for a completely new engine, by which time any airframe would be basically obsolete. These are
extreme examples, the Volksjaeger airframe went from concept to flight ready in about 9months, and the P51 in (aledgedly) 102 days... although its probable
that at least some preparatory work had been put in before as that was the date the contract was "signed", so I`d bet you could probably add a bit.

In reality due to the large disparity between airframe design timelines and the readiness of the engine (usually the aircraft designer had to design
around a "new" engine probably in very early prototype stages such that his plane might still be effective when it was ready in the future)
the engine choice sometimes changes, maybe several times. Often this engine turned out subsequently to not work properly when the
airframe was eventually ready....

Good examples of that being the Me109 and Hawker Typhoon. The Typhoon (actually started as the Tornado) was supposed to have the Vulture engine, then
the Sabre, but also the Centaurus was mooted for it too. All this mish-mash ended up as the Typhoon and Tempest. Sydney Camm certainly had
only a rough idea of which engine was going to be used, wasnt really his fault. I think the 109 went from Kestrel, to Jumo210, to DB601 to DB605
and even BMW801 (Me109X).

Later in the war FW put in loads of effort to explore various options for the 190D, and Jumo213 and DB603 were fully mocked up.

I`d say chaos was the usual order of the day regarding engine choice. The exceptions were very lucky airframe designers !

My (deceased) X-father-in-law was crew chief on P-47s. He said the 'plumbing' was a nightmare to work on, referring to the engine "system." And this was an aircraft used extensively for low level strafing! I wish now I'd spent more time getting more details from him, other than all the HORSE MEAT they ate in England (off base).