Page Content (OCR)
work, which included the evaluation of new materials for use at high altitudes. These would find their way into several prototypes under development by Vought for the US Navy. Although security at Vought’s plant was extremely tight and R&D was highly compart- mentalised, Smith was eventually shown the latest partly-completed secret jet fighter (thought to have been the XF7U-1 Cutlass) and a totally unacknowledged VTOL version of the Skimmer. According to Smith, this air- craft was flown from a prone position. It used a gas turbine engine to drive the propellers and was supported on very long forward undercarriage legs. ‘Did the aircraft fly?’ said Smith, pre-empting an obvious question. ‘You bet’, he continued. ‘I saw it take-off, hover and land. It was only tested at night. They'd get it off the ground and it would disappear into the darkness.’ Apparently, there were soon plenty of local stories in circulation about unidentified objects seen in the night sky around the company’s airfield. ‘Those of us that worked on the project’, said Smith, ‘got a chuckle about these reports, since we knew what they had seen’. Smith went on to explain that he left Vought in 1947 when the company moved to Texas and he believes the prototype was taken there. Unfortunately, there are no documents avail- able to support Smith’s account and this intriguing story remains uncorroborated at the present time. Nevertheless, there were at least two alternative layouts for the proposed third- generation military turboprop Skimmer, and the first was very similar to Smith’s description. This design featured a centrally-positioned axial-flow gas turbine that was shaft-coupled to each propeller. Exhaust gases were vented through a port in the tail and this led to the use _—_ Above left: Postwar design by Zimmerman for an of two tailwheels rather than one. articulated tail to facilitate easier VTOL operation. The second design appears to have hie involved a straightforward gas turbine substi- Apove right: Design study by John Sullivan in 1954 tution for both of the air-cooled radial engines, _ to produce a more advanced VTOL version of the which were shaft-coupled to each propeller. Skimmer using a complex landing gear system, This option was briefly discussed in a US Navy a rotaung cockpit and additional jet power. aviation document from October 1946, which suggested a VTOL capability and better level- flight performance than the XF5U-1. The first illustrations of VTOL Turbo-Skim- _ to build a civilian version of the VTOL Turbo mer designs show a complicated undercar- Skimmer, which was capable of carrying a riage system, with two fully retractable _ pilot and two or three passengers in a swivel- forward struts that provided a maximum ele- ling cockpit. Perhaps the Skimmer could vation of around 35°. These double-action have been developed into a useful utility air- stilted legs would provide VTOL in the fully craft if adequate funding had been made raised position, or a rolling take-off when the __ available for further R&D, but reliability of the legs were partly retracted and the aircraftwas power transmission system left much to be lowered. Zimmerman produced a number of _ desired and the behaviour of the articulated increasingly complex designs for the Skim- _ propellers was poorly understood. mer’s undercarriage, with the most compli- On 9th July 1947, an unidentified heel- cated arrangement allowing the aircraft to sit shaped aircraft with the same distinctive in an almost upright position. This was made _ sound as an Allison-engined P-80 Shooting possible by re-designing the rear of the air- Star passed over Phoenix, Arizona and wide- craft to act as a flap that would swing forward _ spread sightings were reported in the Arizona when on the ground. Perhaps it would have — Republic newspaper. Witnesses said that the worked, but adding this much extra com- aircraft flew in from the west and later plexity to an already troubled design would _ returned in the same direction, towards Cali- not have been popular with most engineers. fornia. There have been persistent rumours Some documents indicate that Vought pro- _ that at least one experimental jet-powered posed an advanced turboprop Skimmer with _ disc-shaped aircraft was built for the US Navy a VTOL capability for a joint US Navy-USAAF during this period, but no documentation can design study called Project Hummingbird, _ be found to validate the suggestion. It is con- which began in April 1947. This may have _ ceivable that a black-domain jet-powered air- been the case, but the only designs to reach craft along the lines of a fourth generation development were tail-sitters produced by Skimmer was completed as a one-off STOL Ryan, Lockheed and Convair. prototype and perhaps the details will even- After the War, Zimmerman revived and _ tually surface, along with those of Smith’s updated his Aeromobile concept and hoped _ secret nocturnal prototype. Above left: Postwar design by Zimmerman for an articulated tail to facilitate easier VTOL operation. US Patent Office Above right: Design study by John Sullivan in 1954 to produce a more advanced VTOL version of the Skimmer using a complex landing gear system, a rotating cockpit and additional jet power. via Bill Rose 34 OO Secret Projects: Flying Saucer Aircraft