A secret aviation invention from World War I

In my work as a patent specialist I was often asked about secret inventions for military use. Today I researched the history of a British secret invention which is rather sad, as the inventor died tragically.

Like many other countries the UK Patent Office either suppress or delay the publication of militarily sensitive patents. One that was delayed was GB1915/17082, which was for a method of training pilots so that bombs were dropped accurately. The basic idea was that it was a mirror which was placed by an operator in the middle of an airfield, and could be used to check if the pilot had "dropped" an imaginary bomb on the right spot (that is, where the operator was). Ruled lines were used to monitor the accuracy in this first, 9 page version, Optical apparatus for use in connection with aircraft. It was filed on 4 December 1915 but was not published until 5 July 1923, having been, as the printed patent states, "withheld from publication under Section 30 of Patents and Designs Acts, 1907 and 1919". Here is the main drawing.

The applicant is given as Thomas Archibald Batchelor, Flight Lieutenant R.N.A.S., Admiralty. The only reason I found it was that I knew the patent number. That was mentioned in files at the UK National Archives (TNA) released in the 1980s. The Espacenet database only indexes the patent by the publication number and the words in the patent summary -- which does include his name (as Batchelor, T.A.) If this is typical of secret patents then the way I found it may be helpful to others.

The TNA catalogue lists numerous files in class T173, the papers of the Royal Commission on Awards to Inventors, which cover 1919 to 1937. It was to determine compensation for patented and unpatented inventions used in World War I. Many of the folders are for the correspondence of a single request for compensation by the inventor or his/ her representatives. The advanced format of the Discovery online catalogue can be used by specifying T173 in the "Search within" area while specifying a name or a topic in the first boxes. That would find folder or "piece" T173/108, described as

Claimant(s): Batchelor, Mrs. U. Nature of Invention: Bomb-dropping mirror

I also found that there was a second folder for Mrs Batchelor, T173/554, for a bomb sight, by looking for her name.

I spent ten minutes studying these folders, but they needed hours. Usually there is little or no information other than the patent for an old invention, yet here there were many pages. I only had a quick look, from which Una turned out to be her name, and her deceased husband was called Major Batchelor. Her address was given -- 30 Hampstead Road, Preston Park, Sussex. Basically the folders consisted of an exchange of letters, with some memos, between the widow and the authorities, in which she asked for compensation for his invention.

They replied that he had been employed to do research work and had been paid an extra £500 anyway, for the 273 mirrors made for the British forces, but she wanted compensation for the 41 made in the USA for the US forces. £1000 was her price. It was mentioned that Batchelor had been a paymaster in the Royal Navy who had trained to be a pilot. He had crashed and died in a Handley-Page aircraft.

I had assumed that he died in the war, but an item dated May 1 1919 on the Flightglobal archive revealed that he died, as a Major in the RAF, and who had received a DFC, on April 22 at the age of 32 in a flying accident at Andover aerodrome. Not only did he die in an accident, the war had been over for several months. A brave bombing raid by Batchelor is described in an August 1918 issue of the same magazine.

The papers refer to an improved version of the invention that did not require the ruled lines, but this is not the same as his patent that was applied for on 13 April 1917 and was accepted for publication in 1921 as Range-finding apparatus for use upon aircraft. There was a co-applicant, Lieut.-Commander Harry Egerton Wimperis, of the Royal Navy Volunteer Reserve. Here is the main drawing.

Wimperis had 20 patents, mostly on aviation. He is described in the first patent as an engineer, in 1909. He turns up a lot in the Batchelor folders, including the transcript of his making statements in some sort of courtroom on behalf of the widow, where he is called Major Wimperis. He was in some difficulties as he admitted that he was also supposed to be involved in helping decide if inventors should be paid compensation. Hence there was a conflict of interest.

There are also papers from the American side, including an impressively set out letter, with a huge blue seal on it, signed by no less than Billy Mitchell, the distinguished pilot and general.

The verdict ? The official side claimed it was not new, referring to the earlier work in GB1915/9354 and in US1121309, and talked of offering her £50. It does not seem that Batchelor's widow received even that.

This is merely one of many stories hidden away in the archives.