Metrallaroja
Airman
- 97
- Nov 21, 2020
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As I said:Please, mate, need little bit more explanation
On these two graphs I only see:
- zero RAM: two runs (different engines), with 70 and 70.5 inch (high gear: 2300 HP at critical altitude 6000 ft)
- so-called "420 mph" RAM runs: with 70.1 and 70.3 inch (high gear: 2350 HP at - thanks to RAM - critical altitude approx. 11000 ft)
Where's something written about the figure 59.5 or 60 inch?
Are the low gear full throttle runs (2350 HP without, and 2800 HP with RAM) not also at approx. 70 inch - if not, why so?
Ram effect increases MAP above the zero ram critical alt.
In this case, the R-2800-34 low gear has the zero ram critical alt for 70'' 2800HP below SL, so it needs ram to get to 70''.
At zero ram it only gets to 59.5'' that is why it produces 2350HP with zero ram.
Ram increases the MAP to 70'' and so the engine power increases to about 2800hp.
The images I already sent.Hmm, what did you mix?
Zero ram power:
View attachment 675649
Zero ram MAP:
View attachment 724318
420mph ram power:
View attachment 675650
420mph ram MAP:
View attachment 724319
Great!They are the same runs, look at ''plate numbers'' and the description below
You can find the plate numbers on the bottom right corner:
View attachment 724456
2 is the 420mph MAP already posted View attachment 724319Great!
Is it possible to show "plate 2, 3 and 6" as .jpeg or .png files? (better for me)
"Absolute Supercharger Rim Pressure"I think CAT is carb air temperature and CAP is carb air pressure, but ASRP has me stumped. Must be some form of manifold pressure. Can anyone decipher it?
I`ve read a very large portion of the Napier company archive papers, and I`ve never seen a Sabre test curve above 3050 hp (NS.96 SM 3850rpm, takeoff powerGetting back to the Napier Sabre producing 5000 hp.
In the Aeronautical Journal volume 79, Issue 777, September 1975 there is a review of the book "Some Unusual Engines" by Setright. The reviewer is Air Commodore F.R. Banks, and he states this about the Sabre:
"Further, the Sabre never achieved 5500 bhp. The maximum (quoted by the reviewer [Banks] in his James Clayton lecture of 1951) was 3000 bhp on 100/130 grade fuel plus water/methanol injection."
Ricardo in "The High-Speed Combustion Engine" Fourth Edition states:
"It gave a take-off and combat power of no less than 3050 B.H.P. when running at 3850 r.p.m. and had shown itself capable of a sustained output of 3600 H.P."
I suggest that:
- 5000/5500 hp is a myth dispelled by a very well respected figure in Aircraft engines
- 3600 hp could be squeezed out in the Napier test bay during a long term test but with plenty of cooling water. I would consider Ricardo a dependable source.
- 3050 hp with ADI is the real maximum figure. I expect there is a type test somewhere to verify this, although I have never seen it.
I have attached Banks James Clayton lecture. It doesn't say much that we don't know.
By 1941 the series II, with its maximum output of 2090 B.H.P., had overcome most of the teething troubles and this engine was chosen to power the Hawker Typhoon, then Britain's leading fighter aircraft.
Interesting. "... in 1945 the series VA ... gave a maximum output of 2,600 B.H.P." Anyone have anything more on 2,600 bhp with the Sabre II? Given that the Sabre II gave ~2,420 b.h.p. at 3,850 r.p.m. and 11 lb, what boost would give 2,600 B.H.P.? +13 maybe?
It was poorly made until outside help from IIRC Bristol was brought it. Though it's noteworthy that none fly today when hundreds of Merlins fly on.Sabre was a terrible engine, the RAF was very glad to be rid of the relentlessly troublesome creature
That may due to the numbers involved and size/complexity of the engine.Though it's noteworthy that none fly today when hundreds of Merlins fly on.
The Standard Data Pages for Reciprocating Engines for the Napier Sabre has the VA has 2,300hp @ 3,850rpm, +12psi for take-off, 2,600hp @ 2,500ft, 3,800rpm, +15psi boost in low gear, and 2,300hp @ 12,750ft, 3850rpm, +15psi boost in high gear.
This is from http://www.wwiiaircraftperformance.org/Aircraft_Engines_of_the_World_Napier_Sabre.pdf