Talk:CC Gear synchronization

The story
This arose through a curious set of circumstances, the first of which was a chance meeting in Whitehall between Major Colley and Admiral Lord Fisher. Fisher was looking for a soldier with gunnery experience to join the new Invention Board, to liaise with the Navy and keep an eye on inventions that might be suitable. Major Colley was just the man he wanted, and he had him appointed as Chief Experimental Officer and Artillery Adviser of the War Office Munitions Invention Department.

Soon after this appointment Major Colley attended a committee meeting of the Invention Board where a suggestion to heat trenches by means of Wave Transmission" was dismissed because the inventor, a mad  Romanian'', had stated that water was compressible. The Wave Transmission file,  placed on top of the high pile of dossiers overbalanced and slipped on to the pad in front of Major Colley. Being disinterested with the rest of the proceedings he opened the file and began to read the theory of Wave  Transmission submitted by George Constantinesco. He was so interested in the  inventor's claims that he took charge of the dossier and on the following day  visited George at his laboratory at Alperton. He was so impressed with what he saw that at the next committee meeting he urged that the case for Wave Transmission should be reconsidered. The result was still negative and he was informed that he was not to encourage the inventor and that no  funds could be made available for further investigation or research in  connection with the invention.

Major Colley was so incensed at the attitude of his department that this was the cause, eventually, of his leaving, and having asked for a written order to the effect that he was to have nothing to do with the invention, one was supplied. Subsequently he received orders from the War Office to join a battery.

In the meantime Major Colley had many interviews with George Constantinesco in an endeavour to see in what manner his invention could be put to  practical use in war. George suggested many, one of which was the silent and flashless guns for firing projectiles, but which had already been turned down  because their operation relied on the compressibility of liquids.

It was during one of these many interviews that Major Colley suggested that George attempt to so synchronize the firing of a machine gun so  that the bullets would not strike the propeller. He did not know what gave him this "brain wave'' because he had nothing to do with aircraft at the  time, but as soon as he was assured by George that he could construct such a device, he called (unofficially, since he was ordered to have nothing to do with Mr Constantinesco) on the Flying Corps and ascertained that such a device would be invaluable. That department was in a state of  transition as the Royal Air Force was on the point of formation, and had no funds available for research and no spare equipment. He decided, therefore, to go to the Arsenal and see his old friends where he managed on his own  responsibility to obtain the loan of a Vickers machine gun and 1,000 rounds of  ammunition. He took these to the Flying Corps and placed them in touch with George Constantinesco.

The officers that Major Colley placed in touch with George Constantinesco included Colonel Blacker, lieutenant Colonel Caddell and Major  Hopkinson, all from the Department of Military Aeronautics. The Vickers machine gun and 1,000 rounds of ammunition were duly delivered to George at his laboratory at Alperton. He immediately started work on developing a gear to operate the gun trigger synchronized to the speed of the engine using his wave transmission system, which he had already applied to his rock drill. Within 10 days, in May 1916, he had prepared the first drawing and an experimental model of what became known as the Constantinesco Fire Control Gear or  the "C.C. Gear''. George submitted his first provisional patent application for the Gear on 14th July 1916 (No. 512). The Patent for the complete  specification was granted on 17th July 1919.

In the first test of the model an electric motor drove a disc, at 1,500 revolutions per minute, with the position of the propeller blades marked in chalk. When the gun was activated with a lever 120 rounds of ammunition were fired, most of which passed through the same hole about midway  between the chalk blades. Occasionally a round would go slightly astray by up to an inch, which did not satisfy George. He found this was due to defective rounds. The model was then used to test the quality of ammunition. With good quality rounds, all the bullets passed through the same hole in the disc at all engine speeds.

The next problem was how to complete development of the "C.C. Gear'' to the point where it could be used in fighter aircraft, because George did not have the funds to do so and officially he was not to be  encouraged. After witnessing the trials Major Hopkinson was so impressed that he  defied his superiors and gave George an order, on his own responsibility, for 12 sets of the gear at £50 each. With this assistance from Major Hopkinson George was able to perfect his device, but not without further delays and frustrations in obtaining materials from official sources. In this respect Colonel Blacker did much to ensure that he obtained the  materials he needed.

The first aircraft to be fitted with a fully developed C.C. Gear was a B.E.2c, in August 1916. After successful trials, officialdom was fully convinced of the perfect reliability and superiority of the gear over all the existing mechanical systems in use and its adaptability to any type of engine and airframe. It was clear that all mechanical systems had become obsolete and orders were given to manufacture the C.C. Gear in quantity. Over 6,000 gears were fitted to machines of the Royal Flying Corps and the Royal Naval Air Service (later amalgamated into the Royal Air Force) between March and December 1917 and 20,000 more were fitted between January and October 1918. A total of 50,000 gears were manufactured eventually, having become standard equipment for both the British and American Air Forces.

No. 55 squadron of DH4s, the first aircraft to go into active service fitted with the C.C. Gear, arrived in France on 6th March 1917. Two days later No. 48 squadron of Bristol Fighters and No. 56 squadron of S.E.5s arrived so equipped. From then on a whole range of aircraft were fitted up with the C.C. Gear and arrived in France at regular intervals. The C.C. Gear was designed at first to operate only one Vickers machine gun, but later George produced a modified version which could fire simultaneously two Vickers guns mounted in parallel. The first aircraft to be fitted with the twin gun system was the Sopwith Camel, fig. 7. Figure 8 shows  the trigger motors in a typical twin gun installation.

The C.C. Gear was capable of firing at a rate only limited by the maximum speed of the engine and the maximum firing speed of the Vickers gun. A modification of the Vickers gun by Lt. Comdr. George Hazelton of the Royal Navy boosted the gun output up to 1,000 rounds per minute but the  maximum rate of fire was officially set at 850 rounds per minute to ensure  reliability and safety [8]. With two guns in parallel, the C.C. Gear could produce a safe and reliable fire power of up to 2,400 rounds per minute through the arc of one propeller without hitting the blades2.

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