Sikorsky S-57
| Sikorsky S-57 | |
|---|---|
| Type: | Convertible plane |
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Project |
The Sikorsky S-57 (military designation XV-2 ) was a project by the American manufacturer Sikorsky Aircraft to build an experimental convertible aircraft in the 1950s . However, no prototype was built. The S-57 used the rarely used stop-rotor concept to change from helicopter flight to fixed wing mode.
history
In a competition jointly organized by the US Air Force and the US Army at the beginning of 1950, different constructive designs of convertible aircraft were examined in concept studies. This also included wind tunnel tests and the construction of airworthy specimens. The subsequent testing should show the possible uses for observation and reconnaissance missions as well as the suitability of the various concepts for larger aircraft. The three constructions selected were the Sikorsky S-57, the McDonnell XV-1 (a combination aircraft with a blade tip drive) and the Bell XV-3 (a tilting rotor convertible aircraft ). Sikorsky had proposed the use of a stop rotor, which should be housed in the fuselage with dynamic lift during horizontal flight .
Sikorsky investigated numerous drive configurations for the S-57, with the still low power of the shaft drives in the early 1950s limiting the design options in helicopter construction. This also meant that only a relatively low rotor surface loading of around 0.2 kN / m² was possible. This would have resulted in such a large circular area for the rotor that it could no longer be stowed in the fuselage. The solution was to use a single-blade rotor , which should be equipped with a cold blade tip drive.
The transition phase from hovering to level flight was of particular technical importance, whereby the single-blade rotor had to be brought to a standstill and "tipped" into the fuselage by means of the rotor mast that could be swiveled forward. However, wind tunnel tests with a scaled-down rotor did not produce satisfactory results, so that afterwards a conventional two-blade rotor was used again in the planning.
The work continued until 1958 without the technical implementation problems being completely resolved.
See also
Web links
- History of the S-57 on sikorskyarchives.com (accessed May 2, 2019)