T. E. Lawrence to George Brough

Clouds Hill,
Moreton,
Dorset

5.IV.35

Dear G.B.,

Your two letters were sent on from Bridlington (I left the R.A.F. a month ago) and waited here for me, while I have been dodging about to avoid my enemies, the Press. This will now be my only and permanent address, I hope.

About your fan. Our propeller experiments were all marine, and they showed how little was known yet, even in that much exercised branch. Air propellers (of the suction type) have been, I am sure, very little studied. Large diameter of course means noise, as do broad tips. Four blades are quieter than three and as efficient. You can push an air-prop pitch up to great steepness, so long as the revs are not extravagant. But frankly I cannot help you. Our props had so different an intention. The water is so solid an element. Have you considered Ethylene glycol for cooling? Or is the engine getting too hot for its oil? In the desert I ran a tiny condenser for our old Fords, and so boiled all day without using a pint of water, and with great thermal advantage. Later they doubled the Leader-tank, increased the pump output, and carried on without boiling. Petrol consumption then increased.

I have wondered of late how the new engine was shaping. You were going to make a new angle of inlet for the mixture. Now you are working on the timing gears! Please tell Mr J.A.P. for me that if I had his sized firm and couldn't get an aircooled twin right in 18 months, I'd eat my test-bench and wash it down with my flow meter!

Meanwhile I've only ridden the ancient-of-days twice this year. It goes like a shell, and seems as good as new. The pushbike is a reality, though. I came down here from Yorkshire on it and have toured much of the S. of England on it in the last three weeks. It is dull hard work when the wind is against: but in lanes, and sheltered places and in calms or before winds, wholly delightful. So quiet: one hears all the country noises. Cheap - very! not tiring, up to 60 or 70 miles a day, which is all that I achieve, with sightseeing: and very clean on a wet road.

The loss of my R.A.F. job halves my income, so that my motor cycling would have been much reduced for the future, even without this 30 m.p.h. limit idea. I had half-thoughts of a touring sidecar, for long jaunts, with the push-bike for leisured local trips, but we shall see. The old bike goes so well that I do not greatly long for its successor. If only I had not given up my stainless tank and panier bags and seen that rolling stand! But for those gadgets my old 'un would still be the best bike in the S. of England. Good luck with your fan!

Yours

T E Shaw