The Lympne Light Aircraft Trials were held to encourage the development of practical light aircraft for private ownership, with a strong but not exclusive emphasis on fuel economy. They were held in 1923, 1924 and 1926. Each year saw different restrictions on engine size, framed initially in terms of capacity and then weight. The Daily Mail newspaper provided cash prizes throughout though the initiating donation came from the Duke of Sutherland. The Air Ministry were prize givers in the 1924 event. The trials were held at Lympne in Kent, England.

The Lympne events had their origin in the post-World War I state of aviation in Britain and in Germany. Military aircraft production stopped immediately after the war ended. In Britain there were large stocks of surplus aircraft available at low prices, making it hard for manufacturers to develop new models. Airlines were only slowly emerging, largely using converted military aeroplanes and having not found a certain economic model. The old fighters, though effective for barnstorming were not economical or practical enough for the private owner.

In Germany the manufacture of powered aircraft was forbidden under the terms of the Treaty of Versailles, but glider development was allowed. In 1921 a glider competition was held in the Rhön mountains, and in mid-August 1922 another was held at the Wasserkuppe. The 1922 prize of 100,000 marks was won by a flight of 66 minutes, demonstrating the possibilities of engineless flight. In response, the Daily Mail offered a prize of £1,000 to the pilot making the longest flight in England. The Royal Aero Club chose Itford Hill on the South Downs just east of Brighton as a venue and the event was arranged for 16–21 October 1922. This gave contestants just six weeks to design and build their gliders, or to bring them from Europe. Thirteen gliders competed with each other and the autumn weather. The best flight by an Englishman was that made by Fred Raynham in a Handasyde aircraft, lasting 113 minutes, but the Frenchman Alexis Maneyrol did better in his Peyret tandem monoplane, staying up for a world record 201 minutes to win the prize. Given this demonstration of long duration unpowered flight it is not surprising that people began to consider the possibilities of glider-like aircraft, fitted with small engines, as sports aircraft for the private flyer. The first Lympne meeting the following year and its slightly earlier counterpart in Vauville near Cherbourg, France, were the result both of these ideas and a desire to build an aircraft which would satisfy the needs of private fliers and foster private aviation. Unfortunately, in the opinion of many, both at the time and later, the restrictions imposed resulted in aircraft that had too-small engines, wheels that were too thin and of small diameter and engines which, though under powered, were too heavy relative to the often fragile, light-weight frames in which they were housed. C. G. Grey, editor of 'The Aeroplane' at the time devoted two issues to "a four-page long diatribe" to the failures of the 1924 event and the author of 'The Lympne Trials' speaks of "a clear failure to understand what a private pilot or a flying club might need as a training aeroplane". Nevertheless, the trials did serve to stimulate public and industry interest in private aviation after the first world war and certainly exercised the ingenuity of designers to the maximum in complying with the restrictions placed upon them.

Lympne Aerodrome is just west of the village of Lympne, on top of old sea cliffs near the coast and about 3 miles (5 km) WNW of the Kent port of Hythe. The events were organised and administrated by the Royal Aero Club.

The first trial was held 8–13 October 1923. The official proper name was the motor-glider competition. The Duke of Sutherland, at that time Under-Secretary of State for Air got the competition moving, offering a prize of £500 for the most economical British aircraft. The Daily Mail offered a similar economy prize of £1000 for a flight of more than 50 miles over a 12.5-mile triangular course, powered by an engine of less than 750 cc capacity but for an aircraft from any nation. As a result, the competition began to be referred to as the Daily Mail Motor Glider Competition. Rules were few, but the newspaper's inclusion of a capacity limit with its generous prize was adopted by all entrants. Since a single-seat aircraft was bound to be lighter and more economical than a two-seater, all entrants were single-seaters.

The original intention was to fill the aircraft with one gallon of fuel and see how far they got. Seeing that this would lead to aircraft retrieval problems, the organisers decided that all flights must begin and end at Lypmne. Instead, each was fuelled over a gallon by a standard amount, landing when they judged they had insufficient fuel for another 12.5 miles. If they had used more than one gallon, the calculated consumption was pro rata; if they had used less than one gallon the consumption was nevertheless based on one gallon used.

Before an aircraft could enter the fuel economy test it was required to pass a demonstration of portability, called the transport test. Each aircraft had to prove it was capable of going through a standard field gate and then be wheeled along a country road for a mile using not more than two men. Because this limited the width of the aircraft to 7 ft 6in then the designs all featured either detachable or folding wings.

Also competed for were the £500 Abdulla Prize, donated by the Abdulla Tobacco Co. for the greatest speed over two laps of the same circuit and £150 each from the Society of Motor Manufacturers and Traders and the British Cycle and Motor Cycle Manufacturers and Trade Unions for the greatest number of completed circuits during the whole competition. Sir Charles Wakefield of Wakefield Oil (Castrol) offered £100 for the machine that attained the greatest altitude. These were large sums of money at a time when £80 would buy a sailplane in Germany. The object of the competition was to produce a motor glider that cost no more than £100.