The Udet U 3 was a small, low-power sport aircraft developed in Germany in the early 1920s as an improved version of the Udet U 1.Taylor 1993, p.873The Illustrated Encyclopedia of Aircraft 1984, p.3035Bichel 2013, p.39
Some confusion exists today around the Udet U 3 and U 4 designations.Bichel 2013, p.39 In an article written in 1925, Udet Flugzeugbau chief designer Hans Henry Herrmann attaches the U 3 designation to the Udet aircraft that competed in air races in Argentina in 1923.Herrmann 1925, p.208 Photographs of this aircraft show it to be a single-seater,Bichel 2013, p.39–41 although a contemporary account of the aircraft describes it as a two-seater,, cited in Bichel 2013, p.39 At least two later reference works apply the U 4 designation to the aircraft that raced in Argentina., cited in Bichel 2013, p.39, cited in Bichel 2013, p.39 while a contemporary photo of an aircraft entered on the German registry as a U 4 (D-203, registered to Bäumer Aero in Hamburg) shows a radial-powered two-seater with a forward fuselage contoured very differently from the aircraft that raced in Argentina.Bichel 2013, p.43
Attempting to reconcile the various discrepancies, aviation historian Olaf Bichel speculates that the U 3 and U 4 might have been very closely related designs, and even possibly that they were convertible between single-seat and two-seat configurations via a removable fairing over the forward cockpit. When Bichel wrote his monograph on the various Udet-produced aircraft, no separate specifications were available for the U 4.
Design The U 3 was a low-wing cantilever monoplane of conventional design.Bichel 2013, p.42 It was powered by a single, piston engine mounted in the nose, driving a two-blade tractor propeller. It had a conventional tail and conventional, tailskid undercarriage. The pilot sat in an open cockpit.
The fuselage was of all-wood construction. The wings were wooden as well, covered in fabric. The tail unit was built from steel tube, and also fabric-covered.
The U 1 and U 2 had been powered by two-cylinder engines of , which had proved insufficient. Instead, the U 3 was fitted with a five-cylinder radial engine with nearly 60% more power.
Operational history By 1923, it was apparent that the founding aim of the Udet Flugzeugbau company, selling low-price aircraft to the United States, was unrealistic.Bichel 2013, p.31 Therefore, an invitation for company founder Ernst Udet to compete in the ("Wilbur Wright Cup") in Argentina was timely because it provided an opportunity to promote the company's products in a new market.
One U 2 and a U 3 were shipped to South America, arriving on 28 May 1923. They were transported to the at El Palomar for assembly. On 10 June, Udet demonstrated both aircraft at San Isidro in their first display flights. Five days later, he and friend Max Holtzem flew the two aircraft to Rosario as another demonstration. Udet himself returned to Germany before the was contested.
On 5 August 1923, in the first round of the competition, the U 3, flown by Eduardo Olivero covered the course in 1 hour, 6 minutes, and 15 seconds, finishing in 9th place.Bichel 2013, p.41 In the next round, on 19 August, Olivero flew the U 3 to an altitude of , but was unsuccessful in this round. It did, however, win first place in a handicap race out of a field of 22 competitors, including against a Fokker C.V with an engine eight times more powerful.
On 19 November, Olivera flew the U 3 in a different competition in Argentina, the "19 November Prize". The course was five laps of a route between Buenos Aires and La Plata, roughly away. Olivero and the U 3 finished in 4th place, with an average speed of .
Olivero won first place with the U 3 in its class in the Rosario–Buenos Aires air race on 9 December, flying the circuit in 1 hour, 9 minutes, and 31 seconds., cited in Bichel 2013, p.42 On 24 May the following year, Luis Luro (brother of celebrated race-car driver Jorge Luro piloted the U 3 in the ("Governor Cantilo Cup", named for José Luis Cantilo, then Governor of Buenos Aires Province). Luro won the prize, with a time of 1 hour, 22 minutes, 39 seconds.
Specifications
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