Granville Bradshaw replies to his critics
[Mr. Bradshaw is, we understand, engaged in designing a rotary-type i.c. engine which he naturally hopes will be a Wankel-beater.—Ed.]
The numerous critics of my A.B.C. engines are wrong because they refer to production engines none of which I had any hand in. In my 50 years of design creation I have never emoloyed more than half a dozen skilled mechanics working in a small experimental factory. I have always had a mania for trying to achieve some type of engine that is better than existing types and I believe that I have achieved a fair measure of success.
My first aeroplane engine was a four-cylinder vertical water-cooled with steel cylinders and copper water jackets, for a group in Bournemouth with a very small workshop in Redbridge a few miles from Southampton. That was in 1910 and I suggested the name " The All-British (Engine) Co." because prizes were being offered for " All-British " planes. This resulted in the name A.B.C. That engine took the British Duration Record, and with it The Michelin Cup from Cody (the holder) by remaining in the air for 8 hr. 43 min.
Needing publicity in 1910 we decided to go to Brooklands and when I spotted an old Minerva van chassis with chain drive on the scrap heap I decided to put our aeroplane engine on a roller track at the back with a pusher prop., and a spring balance to measure. the thrust, and drive it to Brooklands by road. I called it the " Wind Wagon " and am wondering if it is still in existence ?
We started early one morning and it was great fun—though a few milkman's horses stood on their hind legs, to the annoyance of their drivers. "Get-a-way" and acceleration were astonishing and when we got to Brooklands to prove the engine by lengthy runs round the track a Weybridge propeller-maker asked to be allowed to test his propellers on it—which, of course, suited our purpose. He "had a go" at the Test Hill and went over the top with ease. He sent for the official time-keeper and broke the Test Hill record at his first attempt—but it was not allowed because we were told that wheel-adhesion played an important part in a car's ability as it involved suspension problems.
We then asked Farnborough if we could try our engine in one of their 'planes but they refused (in writing) on the grounds that " The War Department informs us that there is no military value in the aeroplane." We had taken the only brick-built factory on Brooklands and purchased a few machine tools but we were virtually out of business except for assistance to the many owners of racing cars and motorcycles, who were always wanting pistons eased or cams altered—and I was always keen to help them get records. S. L. Bailey with his Douglas wanted more power, so I designed and made him two new cylinders machined from a steel bar and with overhead valves. He obtained his records iImmediately. And, with little hope for any aeroplane engine business, I designed a flat-twin A.B.C. motorcycle engine.
I quote from the motor Press at the time: " How many people realise that a 350-c.c. A.B.C. with steel cylinders did 72.6 miles per hour over the flying kilometre in 1912—a record, And, later, " A 500-c.c. A.B.C. was the first machine to put the flying kilo. over the 80 mark." Later still, " A 400-c.c. A.B.C. took the much-coveted hour record in the 500-c.c. class on more than one occasion."
These were all " one-off '' engines, built at a cost that must have been infinitesimal compared with present-day motorcycle racing engines. And in those days there were many more firms in the motorcycle racing game than there are today.
I claim to have built the first satisfactory static radial aeroplane engine, which made all others obsolete until the jets arrived and some critics, by searching through back periodicals, mentioned many that few ever saw or heard of. They were certainly not a success because they all overheated and rotating cylinders could be built in larger sizes owing to the increased cooling effect. I successfully overcame the cooling problem by employing extremely thin fins machined on steel cylinders and by heavily copper-coating them, not by copper plating but by de-position to a considerable thickness. Wind tunnel tests that I carried out at 100 m.p.h showed that the temperature at the back was only 2¼ times that at the front whereas without the copper of high heat conductivity the temperature at the rear of the cylinder was some six times greater—causing cylinder distortion and overheating. It was upon this basis that I ventured upon a static radial with cylinders as large as the " Dragonfly."
I was called to London by Lord Weir (who had seen my smaller " Wasp ") and asked to put in hand immediately (with super A1 priority) the largest engine I could design on the same lines and my first " Dragonfly " was built by my six mechanics and was on the test-bed in exactly one month. We had a calibrated prop. from Farnborough and before a crowd of " brass hats " and officials, with myself at the controls, it was started up. It ran perfectly from the start and after ten minutes (never able to resist the desire to know the worst) I had it on full throttle and turning the calibrated prop. at 365 b.h.p. The Americans were there and took drawings away with them. I was also ordered to send complete sets of drawings to 180 firms in this country as Lord Weir said he was immediately going into production.
But the Technicians from The Ministry stepped in, saying that the design must be thoroughly examined by their Technical Experts. I never saw them, or the engine, or the drawings again but I learned later that they had increased the weight by about 70 lb., had reduced the b.h.p. to about 320, and wasted six months in doing this and we all know that the modified engines gave troubles of many kinds.
My own engine had done 72 hours on the test-bed, had beaten The British Height Record and The British Speed Record (details of which were withheld for security reasons) and had made rings round the latest 240-b.h.p. German 'plane that had landed in our territory. I claimed an award and got £43,000 but my small company had financed the building of three " Wasps " and two " Dragonfly " engines as well as sending drawings all over the World.
However, the war was over, giving me further scope for more advanced design work. The A.B.C. car project was bought up by an outside group and I left them to it, after I had built the first three model's. I always left production to Production engineers, as their problems did not interest me.
I designed the A.B.C. motorcycle and the first model was built and on the road in 11 days. It took an enormous number of orders at the Olympia Show and the designs and rights were sold to a woodworking aeroplane factory unskilled in this class of work and they went into big production without any preliminary road tests. How could they hope to make a success of a type so revolutionary?
The German B.M.W. firm came to our A.B.C. works and acquired rights and at their request I increased the engine size to 500 c.c. How heartily I was cursed when it came over, and was the first machine of foreign manufacture to win our T.T. race.
Then I was asked to design the P. & M. Panther 500-c.c. motorcycle engine. Here I decided to go one better and to totally enclose the overhead-valve mechanism. This enclosure is now standard practice throughout the World. They were a sound and experienced firm and I am pleased to see in the last Show Report by one of the motorcycle papers on the model at the Show " This machine beyond any shadow of doubt has the longest production history in the motorcycle industry."
Following the A.B.C. motorcycle I was asked by a friend (who had formed a new company) to design him something simple in the lightweight and cheaper type of Motorcycle. I designed and built him the first motor-scooter in the world (the A.B.C. Skootamota)-and told him that I felt that in the future there would be a growing market for improved designs on these lines. I was not far out, I think.
Next I designed the Belsize Bradshaw and, immediately the first one was built and the engine started, I was told to keep strictly to their trial course so that when things fell off I could be towed back. But, to my mechanic's astonishment, I told him to show me the London Road (it was a cold night and an open chassis) but I went right through and did 1,000 miles without trouble of any kind. Then I took it back and handed it over.
I was then asked to design an engine for Dormans of Stafford and, still out for something better than anything else, I designed them a 2-litre engine (four cylinder) with twin-overhead camshafts (the first in this country, if not in the World). The cams directly attacked small piston's sliding above the valve stems, and this was shown at Olympia. It was copied the following year by two other firms (one of which came and apologised to me for wholesale copying), but it was eventually dropped until the problem of driving the o.h.v. mechanism was satisfactorily solved.
My A.B.C. motorcycle engine was fitted to an English Electric small 'plane and won the low consumption record of 85 m.p.g. and my " Scorpion " engine (a modified A.B.C. car engine) which was used in the first (or second) De Havilland 'plane in the contest, has just been replaced so that both of these have gone to the museums or early aircraft types.