Sikorsky S-52

Infobox Aircraft
name= S-52


caption= Sikorsky S-52
type= Helicopter
manufacturer= Sikorsky Aircraft
designer=
first flight= 12 February 1947
introduced= April 1951
retired=
status=
primary user= United States Navy
more users= United States Army United States Marine Corps United States Coast Guard
produced=
number built= 93 (including four Army trials aircraft) [Polmar, Norman, and Kennedy, Floyd D., Jr. "Military Helicopters of the World" (Annapolis, MD: Naval Institute Press, 1981), p.288.]
unit cost=
developed from =
variants with their own articles = Sikorsky S-59

The Sikorsky HO5S-1 (company model S-52) was a utility helicopter developed by Sikorsky Aircraft in 1950, used by the U.S. Navy, Marines, and Coast Guard (as the HO5S-1G). [Donald, David, ed. "Encyclopedia of World Aircraft", (Etobicoke, Ontario: Prospero Books, 1997), p. 840, "Sikorsky S-52".]

Design and development

The prototype S-52, first flown in 1947, was a two-seater and used a 178 hp (133 kW) Franklin air-cooled flat-6 piston engine (like that used in the Tucker Torpedo). [Donald, p. 840, "Sikorsky S-52".]

It was modified as the S-52-2, a four-seat helicopter using a 245hp (183 kW) Franklin O-425-1 air-cooled flat-6. It had a semi-monocoque fuselage of pod-and-boom arrangement with large bubble-like front greenhouse, [Polmar and Kennedy, p.288.] three-blade rotor, and quadricycle fixed landing gear. The production S-52-3 (HO5S-1) incorporated a downward sloping (anhedral) v-tail stabilizer. [FAA type certificate] It also had sliding doors on the forward front and left rear sides, and a vertically split front bubble, allowing the left half to swing open in a clamshell fashion. The engine was placed at the aft end of the cabin and was canted forward 30 degrees to couple with the clutch and transmission. [flight manual at page 5] The pilot in command occupied the right front seat.

The first American helicopter to have all-metal rotor blades, [Polmar and Kennedy, p.288; Donald, p.840, "Sikorsky S-52".] the prototype [Donald, p.840, "Sikorsky S-52".] set several speed and height records in 1948, including 129.6 mph (204.2 km/h) on a 3 km (2 mi) course, 122.75 mph (197.54 km/h) on a 1 km (1100 yd) circuit, and absolute height 21,220 ft (6468 m). [Polmar and Kennedy, p.288.] It was capable of hover out of ground effect at 5,900 ft (1,798 m) or 9,200 ft (2,804 m) in ground effect. [Polmar and Kennedy, p.288.] The S-52 is widely believed to be the first helicopter to be looped, as flown by Harold E. Thompson in 1949.

The S-52 also served as the basis of the turbine-powered S-59, which as the XH-39 competed for and lost the contract that produced the Bell UH-1 Iroquois. This aircraft differed in having a four-bladed rotor (against the S-52's three) [Polmar and Kennedy, p.288.] and retractable tricycle gear. [Polmar and Kennedy, p.288.]

Operational history

The Navy operated the aircraft as a utility type, and it was used by the Marines for observation and scouting in Korea, [Polmar and Kennedy, p.289 caption.] where the HO3S proved more popular. Four S-52s were evaluated by the United States Army for utility use, as the H-18, but not purchased in quantity. Harding 1990, p.228.]

Many of the former military HO5S-1 units were demilitarized, rebuilt, and licensed as civil aircraft by Orlando Helicopters, who acquired the parts inventory from Sikorsky. A successor operation, Vertical Aviation Technologies based at the Orlando-Sanford airport in Florida, now offers a kit-built "Hummingbird" helicopter based upon the Sikorsky design, using many Sikorsky components such as the rotor head, blades, and transmissions, with some changes to the doors, nose, tail, and trim system, and the substitution of a more modern Lycoming engine. [ [http://www.vertical-aviation.com/ Vertical Aviation Technologies, Inc ] ]

Operators

;USA
* United States Army
* United States Coast Guard
* United States Marine Corps
* United States Navy

pecifications

aerospecs
ref=
met or eng?= eng

crew=2
capacity=2 troops
length m=11.95
length ft=39
length in=2½
span m=
span ft=
span in=
swept m=
swept ft=
swept in=
rot number=1
rot dia m=10
rot dia ft=33
rot dia in=
dia m=
dia ft=
dia in=
width m=
width ft=
width in=
height m=2.99 m
height ft=9
height in=9½
wing area sqm=
wing area sqft=
swept area sqm=
swept area sqft=
rot area sqm=
rot area sqft=
volume m3=
volume ft3=
aspect ratio=
empty weight kg=749
empty weight lb=1650
gross weight kg=1226
gross weight lb=2700
lift kg=
lift lb=

eng1 number=1
eng1 type=Franklin 6V6-245-B16F (Military O-425-1) air-cooled flat-6 piston engine
eng1 kw=186
eng1 hp=245
eng1 kn=
eng1 lbf=
eng1 kn-ab=
eng1 lbf-ab=
eng2 number=
eng2 type=
eng2 kw=
eng2 hp=
eng2 kn=
eng2 lbf=
eng2 kn-ab=
eng2 lbf-ab=

max speed kmh=176
max speed mph=110
max speed mach=
cruise speed kmh=154
cruise speed mph=96
range km=668
range miles=415
endurance h=
endurance min=
ceiling m=4,724
ceiling ft=15,500
glide ratio=
climb rate ms=6.6
climb rate ftmin=1,300
sink rate ms=
sink rate ftmin=

armament1=
armament2=
armament3=
armament4=
armament5=
armament6=

ee also

aircontent
related=
* Sikorsky S-59

similar aircraft=

lists=
* List of military aircraft of the United States
* List of helicopters
* List of civil aircraft

References

Notes

ources

* FAA Type Data Certificate, Helicopter Specification No. 1H2, rev. 3, July 7, 1961
* GAA Rotorcraft Flight Manual for Model S-52-3 Helicopter, Publication No. SA4045-10 Register 2, Sikorsky Aircraft Division of United Aircraft, 1952.
* Donald, David, ed. "Encyclopedia of World Aircraft", p.840, "Sikorsky S-52". Etobicoke, Ontario: Prospero Books, 1997. ISBN 1-85605-375-X.
* Harding, Stephen. "U.S. Army Aircraft Since 1947". Shrewsbury, England: Airlife, 1990. ISBN 1-85310-102-8.
* Polmar, Norman, and Kennedy, Floyd D., Jr. "Military Helicopters of the World". Annapolis, MD: Naval Institute Press, 1981. ISBN 0-870321-383-0.

External links

* [http://www.globalsecurity.org/military/systems/aircraft/h-18.htm Global Security.org H-18 page]
* [http://avia.russian.ee/helicopters_eng/sik_s-52-1.php Sikorsky S-52-1]
* [http://avia.russian.ee/helicopters_eng/sik_s-52.php Sikorsky S-52-2/HO5S/H-18]