Engine technology free-for-all

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
wuzak
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Re: Engine technology free-for-all

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J.A.W. wrote:I'd reckon.. W..
.. that USAAF V-1710 turbo installations were run by Allison - in a factory test cell - well prior to flight..

& Bell did one such V-1710 turbo scheme (for P-39, but subsequently aborted) long before U.S. entry into WW2..
I don't think so.

J.A.W.
J.A.W.
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Re: Engine technology free-for-all

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Wuzak, are you seriously suggesting that the USAAF would allow its service prototypes into the air..
..sans initial ( & thorough) ground-based engine systems testing?

I doubt that Allison would find handing over their mills to be supercharged - as seen fit by an airframe maker,
- prior to determination of the functional parameters as shown on empirical test.. ..as at all - acceptable..

They would not even allow N.A.A. to - incorporate needful changes - to their mills for the P/F-82..

& The Bell XP-39 prototype flew with a turbo, in `39.. ..if that is what you meant..
"I believe in the Workers Revolution & I believe in the Final Solution,
I believe in the Shape of Things to Come, & I believe I'm not the only one..."
: Pete Shelley (Buzzcocks).

wuzak
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Re: Engine technology free-for-all

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No, I meant that the Allison wasn't tested as a system with the turbo - certainly not before the XP-37, YP-37, XP-38 and XP-39 flew.

Allison supplied V-1710s with exhaust flanges - even ejector exhausts were down to the airframe manufacturer.

No doubt that the engines were ground tested in the airframe, but that was the airframe manufacturer again.

J.A.W.
J.A.W.
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Re: Engine technology free-for-all

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Do you have any evidence to back that - seemingly bold - assertion W?

It is frankly implausible that the engine/turbo system, functional characteristics-wise..
.. hadn't been test evaluated..
..in Allison/GE lab tests.. & long before installation in an actual airframe..
"I believe in the Workers Revolution & I believe in the Final Solution,
I believe in the Shape of Things to Come, & I believe I'm not the only one..."
: Pete Shelley (Buzzcocks).

wuzak
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Re: Engine technology free-for-all

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Vees for Victory. but I can't find the reference just at the moment.

The GE turbo was designed so that the engine would "think" that it was at sea level. That is, the pressure at the carb inlet and the exhaust port was the same as if the engine was at sea level.

wuzak
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Re: Engine technology free-for-all

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Found it:
In hindsight this [turbo problems in the YP-37) points out a major problem with aicraft manufacturing and design concepts as overseen by the Air Coprps Material Division at the time. There was little, if any, of what today would be called "systems integration" being done. Engines, turbosuperchargers, propellers, aircraft accessories, armament and communications equipment were "GFE", that is, Government Furnished Eqipment. The aircraft designers had to briong it all together, but no one was responsible to see that the systems and equipment, along with their controls, operated harmoniously. Fo example, the Allison V-171-C was specified and designed to work with a turbosupercharger, but no Allison engine had ever been run connected to a turbo before those installed on the Curtiss XP-37 and Bell XFM-1 airframes. Furthermore, it was not clear who between Allison, General Electric, Curtiss and Wright Field [Air Corps Materiel Division] had the responsibility to integrate these systems into a cohesive and effective package.
You can also see it in the designs.

The turbo installations for the X/YFM-1, X/YP-37, XP-38 and XP-39 were all different. The X/YFM-1 had the turbo on one side of the nacelle, the X/YP-37 and the XP-39 had the turbo beneath the engine, but with different exhaust manifold layouts and the XP-38 had the turbo on top of its booms, more remote from the engine.

J.A.W.
J.A.W.
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Re: Engine technology free-for-all

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Wow!
If that author has his facts straight - it strains the bounds of credibility..
Thanks for providing that W..
I understand the concept of sea-level atmosphere density boost compensation, however that relates
mainly to the compressor, & for the exhaust turbine gas capture/ducting/venting/regulation/backpressure/overspeed issues to be so apparently blithely cobbled up, its no wonder they had problems, & esp' for tightly packaged fighters.
"I believe in the Workers Revolution & I believe in the Final Solution,
I believe in the Shape of Things to Come, & I believe I'm not the only one..."
: Pete Shelley (Buzzcocks).

wuzak
wuzak
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Joined: Tue Aug 30, 2011 2:26 am

Re: Engine technology free-for-all

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J.A.W. wrote:Wow!
If that author has his facts straight - it strains the bounds of credibility..
Thanks for providing that W..
I understand the concept of sea-level atmosphere density boost compensation, however that relates
mainly to the compressor, & for the exhaust turbine gas capture/ducting/venting/regulation/backpressure/overspeed issues to be so apparently blithely cobbled up, its no wonder they had problems, & esp' for tightly packaged fighters.

At sea level the turbo's wastegate is almost entirely open. Just enough flow to the turbine to keep it spinning, I guess.

The early turbos were also different to the ones that were used throughout the war. The Form 8 and Form 10 turbos that were used in the XFM-1, YFM-1 and XP-37 had the compressor drawing the intake air over the centre bearing in an attempt to provide cooling to the bearing. This didn't work, and the turbo frequently failed. This was fixed by turning the compressor around and having it cantilevered off the shaft, and adding an oil cooler to the circuit.

Packagaing of the turbo and associated systems in the X/YP-37 was poor and made the aircraft impractical for actual use. The intercooler and engine radiators were mounted in the fuselage behind the engine. The cockpit was moved back to the rear, so that his view ahead wasn't at all great. Plus he was rather hot, unless he was stationed in Alaska - which, for a time, some of the YP-37s were.

The installation in the XP-39 was just plain messy. It was very draggy and caused the plane to be way off its guaranteed performance.

Also, as Whitney states in Vees for Victory, only 100 turbos had been made since the Army started playing with them in 1917. They were quite rare, and the ones to suit the V-1710 even rarer, being a new design specifiacally for the job.

J.A.W.
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Re: Engine technology free-for-all

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A curious situation..
NACA did not approve, & I guess that's why they got a stronger mandate for technical over-sight..

In Blighty, it seemed the opposite applied, engine makers had a fleet of airframes on hand for test purposes,
inc' some purpose built types & could even get their hands on foreign machines from the RAF to try ( viz: Merlin P-51)..

European engine & airframe manufacturers..
.. also independently developed alternative engine mounting/cowling/exhaust/cooling arrangements..
..although the best outcomes seemed to come from cooperative efforts.. .. as per DH Hornet/R-R..

RAE Napier Lion turbo set-ups dated from the early `20s too..

& I've seen the Hawker drawings of the proposed ( but never made metal) Typhoon turbo..
.. featuring a GE turbo set flat - in the thick wing profile near root..
.. Bell was mooted to produce it , was to have been fitted with a Chrysler built Sabre..

A classic what-if?
"I believe in the Workers Revolution & I believe in the Final Solution,
I believe in the Shape of Things to Come, & I believe I'm not the only one..."
: Pete Shelley (Buzzcocks).

wuzak
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Re: Engine technology free-for-all

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Rolls-Royce built a turbo Condor in the 1920s. They came to the conclusion that it wasn't worth the extra weight and complexity - at least for a single engine fighter.

A Typhoon turbo would have been interesting, but ultimately just as limited as the regular Typhoon - because of compressibility.

A turbo Tempest, on the other hand....

J.A.W.
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Actually W, Typhoon service Vne at ~525mph IAS - was not matched by the Spitfire - until the 20 Series years later..

Tempest 'laminar flow' wing would not accommodate the turbo where - the Typhoon would.

The US turbo-boosted fighters, even when pumping up to 70" Hg MAP - were slower however..
..at practical combat heights, & certainly up to the optimum FS ratio altitudes - of mech' boosted rivals, too.

Again the USAAF was the only service to invest so heavily in turbos, & in fighters, their best was still the Merlin P-51..
The USN was also satisfied, even with their - more extensive - use of the P&W R-2800 - that turbo-boosted
fighter aircraft were a needless step.. & R-R never had reason to alter their view either..

Early -`20s- turbo-engines were,( per the 1,000hp Napier Cub) fundamentally limited by airframe/role choice..
"I believe in the Workers Revolution & I believe in the Final Solution,
I believe in the Shape of Things to Come, & I believe I'm not the only one..."
: Pete Shelley (Buzzcocks).

wuzak
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Joined: Tue Aug 30, 2011 2:26 am

Re: Engine technology free-for-all

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J.A.W. wrote:Actually W, Typhoon service Vne at ~525mph IAS - was not matched by the Spitfire - until the 20 Series years later..

Tempest 'laminar flow' wing would not accommodate the turbo where - the Typhoon would.

The US turbo-boosted fighters, even when pumping up to 70" Hg MAP - were slower however..
..at practical combat heights, & certainly up to the optimum FS ratio altitudes - of mech' boosted rivals, too.

Again the USAAF was the only service to invest so heavily in turbos, & in fighters, their best was still the Merlin P-51..
The USN was also satisfied, even with their - more extensive - use of the P&W R-2800 - that turbo-boosted
fighter aircraft were a needless step.. & R-R never had reason to alter their view either..

Early -`20s- turbo-engines were,( per the 1,000hp Napier Cub) fundamentally limited by airframe/role choice..
I would think the turbo for either would have to be placed in the fuselage between the wings.

The landing gear, specifically the wheels, would be in the area where the tubo could most likely fit.

Image

The turbo would need to be the same as the P-47's.

wuzak
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Re: Engine technology free-for-all

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J.A.W. wrote:Actually W, Typhoon service Vne at ~525mph IAS - was not matched by the Spitfire - until the 20 Series years later..
That's because it was built like a brick shithouse - not because of a great aerodynamic advantage.

In level flight it was restricted in speed despite the amount of power the engine could give. Because of the wing and compressibility.

Now tell me, what was the mach limit for the Typhoon? Doubtful that it was anywhere near that of the Spitfire's at ~0.85M - I expect it would be about the same as the P-38's, around 0.65M.

J.A.W.
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Typhoon was still faster & more heavily armed than contemporary Spitfires.. ..for years..
..until the Tempest took over..
..both in dive & on the level..
P-38 Mach limit 0.65 = Vne of 420-440 mph IAS..

Tactical trials vs the Spit V showed the Typhoon to have a level speed..

"40mph faster at all levels above 14,000ft, & even faster below that height" ( via Chris Thomas)

Mach meters were not routinely fitted to fighters then, but "Limitations" in 'Pilots Notes'
show the Vne, & certainly the Typhoon could out-dive the wee Spit in tactical trials..

.."High frequency vibration & general commotion" - were the compressibility issues..
(according to test pilot Beamont.. ..but he never had his tail fall off & not for want of trying)..
..& which were ameliorated somewhat by use of the thinner Tempest tailplane used in late production Typhoons..
.. but they were cleared for ordnance dropping dives at speeds above the Spit Vne 'Limitations'..


The Hawker design office drawings for P.1010 ( available at the UK National Archives Kew)..
..clearly show the turbo schemed to lie (almost) flat - in the port wing root area, in from & behind the main wheel-well..
& thus with fairly short ducting..
Wing was modified at the leading edge & incorporated the radiators & other air intakes..

A scheme also considered for the Hawker high-speed bomber, if the Brits had ever got the Sabre's production
sorted in a timely manner..

Another such scheme listed was P.1041 'Mosquito replacement'..
"I believe in the Workers Revolution & I believe in the Final Solution,
I believe in the Shape of Things to Come, & I believe I'm not the only one..."
: Pete Shelley (Buzzcocks).

wuzak
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Re: Engine technology free-for-all

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J.A.W. wrote:Tactical trials vs the Spit V showed the Typhoon to have a level speed..

"40mph faster at all levels above 14,000ft, & even faster below that height" ( via Chris Thomas)
Wel, that is blatantly wrong, since the Spitfire V's ceiling was several thousand feet higher, so at some point the Typhoon clearly could not go faster than the Spitfire V.

The speed difference at 26,000ft was ~22mph. As they went higher, the speed difference would be reduced.

Also, having an extra 1000hp helped - especially at low altitudes where the Typhoon had MS gear and the Spitfire V did not.

Also, we spoke in PMs aboutthe Spitfire XII - which was a match for speed with the Typhoon when it first emerged, but receiving little or no development of its airframe or engine.

J.A.W. wrote:.."High frequency vibration & general commotion" - were the compressibility issues..
..according to test pilot Beamont.. ..but he never had his tail fall off & not for want of trying..
..which were ameliorated somewhat by use of the thinner Tempest tailplane used in late production Typhoons..
.. but they were cleared for ordnance dropping dives at speeds above the Spit Vne 'limitations'..
Of course Beamont never experienced the tail coming off - Hawkers re-engineered the rear fuselage after it happened.

J.A.W. wrote:Typhoon was still faster & more heavily armed than contemporary Spitfires.. ..for years..
..until the Tempest took over..
..both in dive & on the level..
P-38 Mach limit 0.65 = Vne of 420-440 mph IAS..
a) The Spitfires had the option of up-gunning to 4 x 20mm - but that was rarely used. There were some Vc's fitted with 4 x 20mm.
b) The Tempest site has the citical mach limit of 0.83 http://www.hawkertempest.se/index.php/c ... 10-stories. This is the point at which the power requirements to increase speed become far higher. They say it was simlar to the Typhoons - which I find barely believable.
c) Gravity can assist an aircraft to exceed its critical mach limit - as shown by the story of the dive test at the end of teh page.