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Author Topic: 'Increasing the Charge' - how piston engine technology provided the power to fly  (Read 68857 times)

Offline J.A.W.

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This 'Aeroplane' article featuring the R-R Griffon shows useful schematics of supercharger drives,
& an output figure comparison with the R-R Eagle V12 of WW1 - as a means of showing piston engine power progress.

http://www.spitfireperformance.com/RR-Griffon.pdf
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Offline J.A.W.

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Work/research still continues on the venerable piston engine..
This paper considers tribological effects on piston to cylinder liner surface patterning.

http://www.federalmogul.com/en-US/Media/Documents/HighqualitySAEpaper200909PFL1163manuscript2.pdf
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Offline Kevin Renner

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Here, a compact currently commercially available piston engine - that offers upwards of 200hp from 95lbs, un-boosted..

http://www.aaenperformance.com/V4_racing_engine.asp

Less than 5 miles from the house actually

Offline J.A.W.

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Hey, K.R., that's great, can you get down there with an HD Video camera..
& put us up some high-production value 'footage' of the machine on dyno test?

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Offline J.A.W.

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USAAF statistical chart showing WW2 piston engine overhaul hours by type..

http://www.usaaf.net/digest/t115.htm
« Last Edit: June 28, 2014, 08:15:07 pm by J.A.W. »
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Offline tartle

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JAW,
A useful find!
Must do some bmep calculationss to see what accounts for differences... configuration, performance per unit of ? or mechanical design...tbc.
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline J.A.W.

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Yes it is a bit interesting T, but whether the time difference spent on fettling the two V12s was due to the..
..typically Brit nuts 'n' bolts construction architecture of the Merlin, & unfamiliarity with such - or due to being run harder..
..may also be a point of inquiry.. ..certainly the number of parts listed per the Merlin is rather larger than the Allison..
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Offline alertken

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1820 consistently lower than 1830 - the competing engines for C-47, yet post-War civil preference was for Pratt.

Good luck in analysis, but operational, rather than design technical issues may be significant: e.g: this is CONUS Depots: battle damage/ misuse may have been handled more in Theate Depots

Offline JFC Fuller

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Tartle,

This may interest you. I found yesterday a mid-1944 reference to a "three stage" Merlin to possibly be available in 1946 in relation to the Spiteful. I have nothing more than that I am afraid, no type numbers, only this one reference. Perhaps you are aware of some work undertaken in this direction?

Offline tartle

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Fascinating,
It is possible a designer schemed out such a concept but I haven't so far found any evidence.
Is there a possibility that this is similar to a reference I found to a 3-stage supercharger for the Griffon that on chasing it through the paper trail turned out to be a 3-speed supercharger? Not knowing the provenance of what you found I can only speculate...
what are your thoughts?
"... prototypes are a way of letting you think out loud. You want the right people to think aloud with you. - Paul MacCready, aeronautical engineer.

Offline JFC Fuller

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I actually mused exactly the same thing, that perhaps it was a confused reference to a Merlin with the sort of two-stage/three-speed supercharger used on the 100 series Griffon. The original Merlin engine schemed for the Merlin Spiteful variant was the RM.16SM (as used in the Spitfire PR.Mk.X). Of equal interest, to me at least, was an assertion that a Spiteful with the Merlin would have approximately 8-9% more range than the Griffon powered version.

On a lighter note I found myself having considerable sympathy for the people at RR and Supermarine in particular. After all the work undertaken on developing the Spiteful and the high-altitude Griffon to power it the Air Staff decided in mid-late 1945 that their only interest in the type was as a low altitude attack aircraft, so the whole programme was held up as Supermarine worked to install the ability to carry a 1,000lb bomb under each wing. 
« Last Edit: June 29, 2014, 05:37:33 am by JFC Fuller »

Offline JFC Fuller

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I didn't think this picture would work, but it does just about, its from the spiteful files I was looking at, Griffon 65, versus Merlin 66 versus RM.16SM:
« Last Edit: June 30, 2014, 01:21:15 pm by JFC Fuller »