Royce Supercharger Design used in Early Jets

[teeteringhead]

As the subject came up in thread drift in last month's thread on WW2 Luftwaffe capability to get within a few miles of the US eastern seaboard, I thought it best to start a new thread rather that tacking onto that after so long ... so here goes ...

From my posts #28 & 30 on the earlier thread:

...... and following the thread drift on aircraft engine lineage, is it true that RR scaled up Merlin/Gryphon superchargers to make the centrifugal compressor stages of their early jet engines?

...... All I need to do now is find a reference for the compressor design story .....

... which I can now do.

Even earlier than the Merlin or Griffon, the compressor design goes back to the RR Kestrel and R engines of Schneider Trophy fame. I quote from The Power to Fly, by LJK Setright (Allen & Unwin 1971 - ISBN 0 04 338041 7), pp101-2. I quote at some length for the whole context and the joy of Leonard Setright's prose.

....but in 1931,when metallurgy and lubrication, fuel chemistry and supercharging occupied realms of black art rather than of pure science, the R set exceptional standards. It did more, for it set the pattern for future aero-engine development. There no longer remained any doubt that for a compact high-speed aircraft the liquid-cooled engine with in-line cylinders, minimal frontal area and low weight would, when combined with gear-driven supercharging and run at high rates of rotation, provide better results than any alternative power unit It provided dramatic proof of the value of forward-facing ram-air intakes; it provided a basis of knowledge of supercharging that persisted for so long that Rolls Royce's early and successful gas turbine aero engines (the Welland, Derwent and Nene) each used compressors of the same basic design scaled up to deliver a greater volume of air ....

[Herod]

I think you can add the Dart to that list. I always found it a good question for the young lads over a post-flight pint. First time I've actually seen a reference though. Thanks.

[Brian Abraham]

is it true that RR scaled up Merlin/Gryphon superchargers to make the centrifugal compressor stages of their early jet engines

The short answer is no. Also, tis Griffon rather than Gryphon.

Whittle’s original patent (16 March 1930) shows a compressor of 2 axial stages followed by a centrifugal stage but he subsequently only used a double-sided centrifugal compressor because of its greater simplicity (as had von Ohain) and because British companies had more knowledge and experience with this type, from their use in piston engine superchargers. With so much else that was new, risks had to be reduced where possible. In practice, early German axial engines suffered more than centrifugals from poor acceleration, vibration, compressor surge and blade stall problems, although ultimately axial compressors would prove the way to greater power and efficiency.

Contemporary superchargers were capable of 2.5:1 compression ratios at 65% efficiency. Whittle required 4:1 ratio at 80%, which required 3,000 horsepower from the turbine, and at 16,000 RPM. By contrast the Merlin two stage supercharger consumed only 400 horsepower.

The Welland was actually designed by Frank Whittles team at Power Jets, and meant to be put into production by Rover as the W.2B/23. Rover were having trouble producing parts and RR were called in to supply the required items. Rover continued to have troubles and production was taken over by RR. RR incorporated the best features of Whittles W2/500 and the Rover B.26 into a new design, called the B.27 or Derwent. Stanley Hooker of RR was their supercharger expert and there is no doubt that his expertise was brought to bear once RR took over, but RR can not lay claim for the centrifugal compressor in the early jets. The Nene (the Tay was an afterburning version - not to be confused with the 1987 Tay) was a development of the Welland and Derwent and the last of RR's centrifugal jets, the Avon being the next which was axial.

[VnV2178B]

In one of his comments on early jets Hooker said that he tried to better the Whittle Power Jets compressor but couldn't, however he made many that were worse.

VnV

[timmeraw]

What is this..... RR Merlin Supercharger??

Hello,

I picked this, what I assumed was an electric compressor, at a sale along with a bunch of other stuff. When I posted on the local Craigslist asking if anyone knew what it was and how to functionally hook it up, I had this interesting reply from someone:

"Darn near jumped out of my skin when I saw your pic!
Haven't seen one of those since the 1950's.
It was in the South Pacific, probalby at Rabaul.
Those were what the mechanics used to turn over the engines of our P-51 Mustangs. That has got to be extremely rare, and valuable.
Exotic warplane owners would no doubt give thousand$ for that RR Merlin compressor. "

Can anyone here verify if this indeed might be one of these compressors?
Click on this link for my question and some pictures.

What Is This???

I would be glad to send more/larger pictures if it would help.
Thanks,
Tim [email protected]