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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Confidential letter from Vauxhall Motors discussing test results and failures of various Aspin project engines.

Identifier  ExFiles\Box 134\1\  scan0197
Date  14th February 1944
  
Vauxhall Motors Ltd
LUTON BEDS.

TELEGRAMS
CARVAUX, TELEX, LUTON

TELEPHONE
NUMBER 2600 LUTON
EXTENSION NO. 91

Handwritten Note: Rm{William Robotham - Chief Engineer}/h ASPIN FILE!!

WHEN REPLYING PLEASE QUOTE
-> OUR REF. 289/MP/CS
YOUR REF.

14th February, 1944

W.A. Robotham, Esq.
Messrs. Rolls Royce, Ltd.,
DERBY

CONFIDENTIAL

Dear Mr. Robotham,

Further to my letter of 1st February, I have now read our 1939 - 40 reports and have discussed the tests in question with members of the experimental staff who worked on the Aspin project at that time.

By and large, the general impression is one of considerable mechanical trouble and a total failure to substantiate the claim that this type of engine is more or less detonation-proof. It is difficult to understand why Aspin should have been so sanguine of using compression ratios of around 12 to 1 on 69 Octane petrol because there is really nothing in the design to suggest that this is likely to be successful.

The engines that we actually ran on the test bed here were as follows:-

(1) A two-cylinder air-cooled engine of modest size (probably about 750 c.c.) on which only one short run was made. This unit was designed and built entirely by Aspin.

(2) A Vauxhall Ten engine converted by Aspin who designed and made a special head with rotors and bevel drives. The water circulation system was also modified. A number of test-bed runs was made.

(3) A 4 1/8" x 6" single-cylinder National Gas Engine converted by Aspin to a rotary-head job, and lent to Vauxhall for a short time. This was run on producer gas, petrol and benzole for limited periods.

Now as regards our experience with these engines, the first was run on 69 Octane petrol at the inventor's suggestion despite the compression ratio in the neighbourhood of 13 to 1. Extreme detonation and roughness were encountered and within about half an hour we cracked a cylinder head. The test was then abandoned.

P.T.O.
  
  


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