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Travel Air Mystery Ship c/n #1, R614K

The day after the 1928 National Air Races, which were dominated by military fighters, Walter Beech visited Travel Air's engineering department. He was frustrated by the fact that civilian pilots were being beaten by the military and that Travel Air did not any competitive aircraft to change this situation.

Herbert Rawdon was convinced that a new racer must be developed for the upcoming 1929 racing season. Travel Air did not have the money to devote to a single purpose racing machine, so design work would have to be done in his spare time, at home. Furthermore, the effort must be conducted in secrecy, such that even Walter Beech would not be aware of it, until the appropriate time.

Rawdon enlisted the help of fellow Travel Air engineer Walter Burnham. Together they designed the Travel Air “Type R”, in honor of Rawdon's last name. Stress analysis was conducted using the latest Department of Commerce (predecessor to the FAA) airworthiness regulations. Rawdon decided to use this method so that an Approved Type Certificate could be applied for by Travel Air, in the event they decided to market the racer.

Maximum gross weight was calculated as 1,750 lbs. The airframe structure was designed for an ultimate load factor of 12.0, equal to the military requirements of the day. The airframe structure was made from welded 4130 steel tubing. Fuselage longerons were 7/8” dia. x .035” thick. Forward fuselage tubing was 1” dia. x .049” thick. From the cockpit aft, the structure was covered by 1/16” plywood, with fabric tape covering the seams. Sheet metal covered the area between the cockpit and the firewall.

The airfoil used on the wing was RAF 34, a British airfoil featured in NACA report 286. It was selected over the M-6, which was developed by NACA and used on the 1927 Travel Air 5000 cabin monoplane. The airfoil was a constant thickness from the inboard rib to the attach points for the flying and landing wires. From this point, the wing featured a taper to the elliptical shaped wingtip.

The wing spars were constructed from two, box-type spruce beams, which were glued together. The ribs were also from spruce, built up from 5/16” square strips, with 1/16” mahogany gussets. To provide torsional stiffness, the entire wing was covered with 1/16” 3-ply Haskelite mahogany plywood. The weight of both wings, including ailerons was estimated to be 255 pounds. Wingspan was 29' 2”, angle of incidence was 1.75 degrees, and diahedral was 4 degrees.

The engine selected was a high compression version of the Wright R-975 Whirlwind radial. Walter Beech wanted at least 400 hp, for the racer. Guy Vaughan, vice president of Wright, delivered an engine with 425 hp. This was accomplished by modifying the supercharger ratio to 10.15:1, and the compression to 6.5:1.

The propeller was a Hamilton Standard with ground adjustable pitch. Maximum diameter was 8' 6” to allow for ground clearance, with maximum efficiency at 200 mph.

In 1928, NACA developed a pressure cowling at Langley's Propeller Research Tunnel. Coincidentally, their experiments were based on the Whirlwind radial. This pressure cowl was used on the Type R.

Travel Air planned to enter the Wright powered Type R, an identical racer powered by an inline Chevolair engine, and a B11D Travel Air biplane with speed wings and the NACA cowl. In mid July, with the design completed, and materials and component parts ordered, only 10 weeks remained before the National Air Races. A group of 25 skilled men were assembled to complete the efforts.

Construction was completed under high security in the Travel Air factory's experimental shop. According to records kept by factory manager William Snook, the constructor numbers assigned were as follows: c/n 2001 for the Wright powered Type R (registered R614K), c/n 2002 for the Chevolair powered Type R (R613K), and c/n 1267 for the B11D biplane (R612K).

Travel Air Type R c/n 2001, R614K, made its first flight on August 29, 1929. The first flight was uneventful, with a maximum indicated airspeed of 185 mph. This flight was made without the pressure cowl installed. Later flights with the cowl produced indicated airspeed of 225 mph. In tests flown over a measured two mile course the average of two runs (one downwind, one upwind) was 227.5 mph.

The 1929 National Air Races were a huge success for Travel Air. Both Travel Air Type Rs flew to Cleveland, and were kept out of sight until the races had begun. Doug Davis flew R614K for once for an exhibition, prior to its entry in race No. 26, the free-for-all event on September 2 nd .

Six other aircraft were entered in race No. 26. The Army's Curtiss XP-3A Hawk biplane was powered by a Pratt and Whitney R-1340, producing 450 hp. The Hawk weighed 1,955 lbs. The Navy's Curtiss F6C-6 Hawk was powered by a Curtiss Conqueror D-12, producing 435 hp. The racers were all equally matched with 420-450 h.p. engines. However, R614K weighed only 1,950 lbs, and was specifically designed for racing, making it the favorite.

Indeed, Doug Davis captured the 1929 Thompson Trophy, awarded for event No. 26. He beat the Army and Navy entries, even after circling one pylon TWICE. Doug thought he had flown inside the pylon the first time, and he pulled so many Gs that he blacked out during the first circle. He wasn't sure he had completed the circle, so he circled it again.
 



 
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