Sikorsky S-75

Infobox Aircraft
name= S-75 ACAP


caption= Sikorsky S-75 ACAP all-composite test aircraft
type= Experimental helicopter
manufacturer=Sikorsky Aircraft
designer=
first flight= July 1984
introduced=
retired=
status=
primary user= United States Army
more users=
produced=
number built= 2
unit cost=
developed from = Sikorsky S-76
variants with their own articles =

The Sikorsky S-75 was a proof of concept all-composite helicopter. Composite materials were used to replace metal to provide greater strength, lighter weight, lower manufacturing costs, and reduce maintenance costs.

Design and development

The Sikorsky S-75 was developed under the US Army's Advanced Composite Airframe Program (ACAP), the goal of which was the development of an all-composite helicopter fuselage considerably lighter and less costly to build than predominantly metal airframes in support of the LHX program.cite book |last= Harding|first= Stephen|authorlink= |coauthors= |title= U.S. Army Aircraft Since 1947|year= 1997|publisher= Schiffer Publishing Ltd.|location= Atglen, PA, USA|isbn= 96-69996| pages = 251] [http://tri.army.mil/LC/CS/csa/aahist3.htm#LHX Historic US Army Helicopters] ] In February 1981, contracts were awarded to Sikorsky and Bell Helicopters, with Bell submitting its Model D292. The S-75 flew for the first time in July 1984.

The S-75 mated an entirely new composite airframe with the twin turboshaft engines, transmission, and main and tail rotors of Sikorsky's S-76A civil transport helicopter. The S-75's floors, roof and most exterior surfaces were of more ballistically-resistant Kevlar, while most of the aircraft's basic load-bearing structure was built of graphite or a graphite/epoxy blend. The machine was equipped with specially designed impact-resistant crew and passenger seats and high-strength pneumatic shock absorbers on its non-retracting tricycle landing gear, in keeping with the Army's requirement that the ACAP aircraft meet or exceed all existing military crashworthiness standards. The aircraft was flown by two pilots, and could carry up to six passengers in the 100-cubic-foot rear cabin.

Operational history

The S-75 underwent a 50-hour evaluation by the Army, and was found to have exceeded the weight- and cost-saving criteria set in the original ACAP specification. Sikorsky gained a wealth of data on the fabrication and use of composite airframes through building the S-75, and Sikorsky's later designs incorporated many of its features. Testing of the machine continued through April 1985, after which it was withdrawn from service and placed in long-term storage.

Operators

;USA
*United States Army

pecifications (Sikorsky S-75)

aircraft specifications

plane or copter?=copter
jet or prop?=prop

ref=U.S. Army Aircraft Since 1947, Avia.Russian.ee Websitecite web|url=http://avia.russian.ee/helicopters_eng/sik_s-69-r.html|accessdate=2007-06-21|title=Sikorsky S-69 / XH-59]

crew= 2
capacity= up to 6 passengers
length main= 43 ft 8 in
length alt= 13.31 m
span main= 44 ft 0 in
span alt= 13.41 m
height main= 13 ft 2 in
height alt= 4.01 m
area main=
area alt=
airfoil=
empty weight main= 6,421 lb
empty weight alt= 2,895 kg
loaded weight main= lb
loaded weight alt= kg
useful load main= lb
useful load alt= kg
max takeoff weight main= 8,470 lb
max takeoff weight alt= 3,820 kg
more general=

engine (prop)=Allison 250-C30S
type of prop=turboshafts
number of props=2
power main= 650 hp
power alt= 485 kW
power original=

propeller or rotor?=rotor
propellers=1
number of propellers per engine=
propeller diameter main=
propeller diameter alt=

max speed main= knots
max speed alt= 184 mph, 296 km/h
cruise speed main= knots
cruise speed alt= 159 mph, 256 km/h
never exceed speed main= knots
never exceed speed alt= mph, km/h
stall speed main= knots
stall speed alt= mph, km/h
range main= nm
range alt= 398 mi, 640 km
ceiling main= 13,500 ft
ceiling alt= 6090 m
climb rate main=
climb rate alt=
loading main=
loading alt=
thrust/weight=
power/mass main=
power/mass alt=
more performance=

armament=

avionics=

References

External links

* [http://avia.russian.ee/helicopters_eng/sik_acap.php Sikorsky S-75 on Avia.Russian.ee]

ee also

aircontent
related=
* Sikorsky S-76
* RAH-66 Comanche

similar aircraft=
* Bell D292

sequence=
* S-70 - S-72 - S-74 - S-75 - S-76 - S-80 - S-92

lists=
* List of helicopters

see also=