Getting 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.
Hi Simon,
First off, a caveat - I'm only providing Setright's text - like you, I find the 5500hp pretty hard to believe.
But I thought I would add what I could from L.J.K. Setright himself, regarding the Sabre. He published a slightly earlier book "The Power To Fly" in 1971, and I quote the following:
[Discussing a Sabre-engined racer project in 1941, a monoplane built by Fairey he states - the Heston racer, page 134]
"The colossal size of the propeller that was specially built for the Heston racer was due simply to the incredible power that it had to absorb, for the Sabre had been brought to such a state that it could deliver a reliable 5500 h.p. at 4200 rev./min., running at about 45 lb/in2 boost and a b.m.e.p. of 467 lb/in2.
By any standards these figures strain the bounds of credibility. In those days the Rolls-Royce R was still considered quite exceptionally highly tuned, in giving 76 b.h.p. per litre at a little less than 300 lb/in2 b.m.e.p., by all those who were not aware of the output of the Daimler-Benz 601 Rekordmotor which mustered 82 b.h.p. per litre at a about 350 lb/in2. Yet here was the Sabre bettering 150 b.h.p. per litre at a b.m.e.p. more than 15 per cent higher than was to be achieved for a matter of minutes only in the Rolls-Royce Merlin some years later, and doing it with complete reliability. In fact this was not the end of the matter, for the Napier engine was run frequently up to 500 lb/in2 and only began to show signs of strain when taken up to 4500 rev/min."
Elsewhere in the same book (page 129) he quotes the Sabre as 3750 h.p @ 4200rpm and 318 lb/in2 b.m.e.p. (in what appears as a more standard rating, comparing it to RR, DB603 etc. He talks of this rating able to be "sustained" on page 136).
Straight talks about a 16' four-bladed airscrew for the Heston racer. While I haven't checked the engine sums, and don't claim the HP figures are accurate one way or the other, this is at least one source of the information you have. In Setright's later book "Some Unusual Engines" (1975), he doesn't repeat the claim in as much detail. He discusses the Sabre, and Napier, in some detail in the earlier book
Would love to know what others can add to confirm or deny plausibility (i.e.: does the quoted bmep match the power/rpm?), or what survives at Napier/RR regarding any of the reported development.
Anyway, my (and Setright's) two cents worth for the day
..... should make for some amusing armchair reading in the responses, if nothing else.....
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