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Sikorsky S-38 / C-6 / RS-4


The S-38 was a nine-seat commercial amphibian powered by two 313kW Pratt & Whitney Wasp radial engines. A sesquiplane wing arrangement was employed and the tail unit was carried on two outriggers running aft from the main wing and braced to the heel of the hull by two struts. It was a successful design and many were built for airline use (including Pan American Airways, entering service in October 1938), private use and for the US Navy/USAAC. The type also set several world records for speed and altitude with specific loads. Over 100 were built from 1928 on



By 1929 the company, having become a division of United Aircraft Corporation, occupied a large modern plant at Bridgeport, Connecticut, and was producing S-38 twin-engined amphibians. A ten-place prototype was built, NC5933, and eleven S-38A were built; NC8000, NC8005, NC8019 to NC8022, and NC8043 to NC8044, with ATC60.
Sikorsky S-38-A NC5933
One special luxury model was built as a personal transport for John H Whitney; NC8005.
The S-38-AH of 1928 (ATC 2-36) was powered by 525hp P&W Hornet A.
A single 12-place S-38A was procured by the USAAC in 1929 for evaluation as XC-6 29-406, also as Wright Field s/n XP-588. Eventually the aircraft, which had a length of 41'0", was used as a VIP aircraft.
Sikorsky C-6
The XC-6 was followed by 10 C-6A production aircraft (30-397 – 30-406), used mainly for transport duties and target towing.
Sikorsky C-6A 30-400
Two S-38A were impressed from Pan American (37854 and 37855) as RS-4.
Two went to the USN as XPS-2.
First flying on 13 March 1928, the 2-10 place S-38-B (ATC 126, 2-74) was priced from $50,000+. Seventy-sic were built; NC1V to NC3V, NC5V, NC7V, NC11V, NC15V, NC18V to NC21V, NC23V, NC25V, NC40V, NC73K to NC75K, NC113M, NC141M to NC146M, NC158H to NC160H, NC196H to NC199H, NC300N to NC304N, NC306N to NC309N, NC943M to NC946M, NC9105 to NC9107, NC9137 to NC9140, NC9143 to NC9144, NC9151, NC9753, NC9775 to NC9776, of which NC9140 was another -38-B Special with two 450hp P&W Wasp C under (2-74), but crashed before its delivery to Colombia.
Sikorsky S-38-B NC9138
1929 S-38-B Special NC9143 and NC9144 (ATC 2-68, 2-69) were S-38-A approved for eleven-place with 450hp P&W Wasp C engines and four-place with Wasp SC, NC9137.
Two S-38-B, NC25V and NC40V (DoC records show as NC16V c/n 314-20 and NC17V c/n 414-8), were converted to S-38-BH in 1929 with ATC2-190 (superseded by ATC356). They sold for $53,000.
The 1932 S-38-BL NC24V c/n 414-15 was a modified S-38-B.
Sikorsky S-38-BL NC24V


The 1932 S-38-BS NC29V c/n 414-20 (ATC2-434) was a seven-place with two 450hp Wasp SC engines. It was built for a 1933 African wildlife survey, flown by pilot Osa and photographer Martin Johnson, with a "Zebra" paint job.
Sikorsky S-38-BS NC29V
The 1933 S-38-BT NC22V c/n 414-23 (ATC 2-446) was an 8-10 place with two 525hp P&W supercharged Wasp T engines.
Selling for around $50,000, ten 1929 S-38-C (ATC 158) were built; NC4V, NC6V, NC10V, NC26V, NC28V, NC111M and NC112M, NC160H, NC199H, and NC305N. By now, 111 S-38 had been built.
Sikorsky S-38-C NC10V
Two S-39-B (NC809W and NC1933/NC14326) were refitted with 400hp P&W Wasp S1 engines in 1931 as S-39-C in 1931. They received ATC 2-391 and 2-436,
The 1932 S-39-CS Special (ATC 2-436) was a four-place with 375hp P&W Wasp S2 engines. The one built, NC52V c/n 914, was for Osa and Martin Johnson.


S-38-A, -B, -C (ATC 60)
Engines: 2 x Pratt & Whitney Wasp, 313kW / 400hp
Wingspan upper: 21.8 m / 72 ft 6 in
Wingspan lower: 11.0 m / 36 ft 1 in
Length: 12.3 m / 40 ft 4 in
Height: 4.4 m / 14 ft 5 in
Wing area: 66.9 sq.m / 720.10 sq ft
Max take-off weight: 4753 kg / 10479 lb
Empty weight: 2970 kg / 6548 lb
Max. speed: 200 km/h / 124 mph
Cruise speed: 175 km/h / 109 mph
Stall: 57 mph
Ceiling: 5480 m / 18000 ft
ROC: 1000 fpm
Range w/max.fuel: 965 km / 600 miles
Crew: 2
Passengers: 10
Engines: 2 x 525hp P&W Hornet A.
Engines: 2 x P&W Wasp, 410hp
Wingspan: 71'8"
Length: 40'5"
Useful load: 3930 lb
Max speed: 125 mph
Cruise: 110 mph
Stall: 55 mph
Range: 750 mph
Ceiling: 18,000'
Seats: 2-10
S-38-B Special
Engines: 2 x P&W Wasp C, 450hp or Wasp SC
Seats: 11 or 4
Engines: 2 x P&W Hornet B, 575hp
Useful load: 3580 lb
Max speed: 143 mph
Cruise: 120 mph
Stall: 55 mph
Range: 600 mi
Seats: 10
Engines: 2 x P&W Wasp SC, 450hp
Seats: 7
Engines: 2 x P&W supercharged Wasp T, 525hp
Seats: 8-10
Engines: 2 x P&W Wasp, 420hp
Wingspan: (upper) 71'8"
Wingspan: (lower) 36'0"
Length: 40'3"
Useful load: 3630 lb
Max speed: 125 mph
Cruise: 110 mph
Stall: 55 mph
Range: 600 mi
Ceiling: 18,200'
Seats: 8-12
S-39-B convert. S-39-C
Engines: 2 x 400hp P&W Wasp S1
C-6 / C-6A
Engines: 2 x P&W R-1340-7
Wingspan: 71'6"
Length: 40'3"
Max speed: 112 mph
Seats: 12


Sikorsky S-38




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