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Sikorsky S-72 (X-Wing)

United States (1976)
Picture of Sikorsky S-72 (X-Wing) Experimental Compound Helicopter Prototype
Picture of Sikorsky S-72 (X-Wing) Experimental Compound Helicopter Prototype Picture of Sikorsky S-72 (X-Wing) Experimental Compound Helicopter Prototype
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The Sikorsky S-72 experimental helicopter of the late-Cold War period was used to test a compound helicopter design - two flyable prototypes were completed before the end.


Detailing the development and operational history of the Sikorsky S-72 (X-Wing) Experimental Compound Helicopter Prototype.  Entry last updated on 11/18/2017. Authored by Staff Writer. Content ©www.MilitaryFactory.com

First flown on October 12th, 1976 the "S-72" was an experimental, high-speed compound helicopter design by Sikorsky Aircraft. The design, born through the Rotor Systems Research Aircraft (RSRA) project, stemmed from a U.S. Army / NASA venture (with work handled by Sikorsky) seeking to collect high-speed data on helicopter rotor characteristics by way of a combination powerplant arrangement. The end-product involved the Sikorsky S-67 helicopter framework coupled with the Sikorsky S-61 main rotor. Beyond the turboshaft engines used to drive the rotor assemblies, additional power was to be had from a pair of General Electric TF34 turbofans situated along the fuselage sides. A low-set, straight monoplane was fitted under the aircraft while the tail rotor (facing portside) was retained. Just two of the aircraft were completed for testing.

The S-72 carried a crew of two or three and had a length of 70.6 feet with a wingspan of 62 feet and a height of 14.5 feet. Empty weight was 21,700lb and the Maximum Take-Off Weight (MTOW) reached 26,050lb. The rotors were powered by a pair of General Electric T58-GE-5 turboshaft engines of 1,400 horsepower each and the turbofan installations were 2 x General Electric TF34-GE-400A engines of 9,400lb thrust. Performance specs included a maximum speed of 230 miles per hour with a cruise speed of 160 miles per hour.


Picture of the Sikorsky S-72 (X-Wing) Experimental Compound Helicopter Prototype
Picture of the Sikorsky S-72 (X-Wing) Experimental Compound Helicopter Prototype


The original S-72 form could be flown with or without the main rotor unit and, due to the uniqueness of the S-72's design, an equally-unique crew ejection system was developed for the compound helicopter to increase survivability of the test pilots. The process involved complete jettison of the main rotor blades via controlled explosives and rockets ejected the crew positions out and away from the fuselage. After a first-flight in 1976 and testing thereafter, NASA received one of the aircraft in February of 1979. Beyond data collection, this model did not progress beyond its experimental design.

An offshoot of the S-72 became the so-called "X-Wing" aircraft which used a rigid main rotor unit (shaped as an "X" over the fuselage) which could be paused by the operator during flight. The aircraft could therefore take-off vertically like a traditional helicopter and then engage forward, high-speed travel with the available turbofan engines, combining the best elements of both aircraft types. Lockheed handled the concept work under DARPA and attention then turned to Sikorsky to modify one of the existing RSRA prototypes for the tests. This product appeared in completed form during 1986 but was not flown for the program was given up for good in 1988.






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Relative Maximum Speed Rating
Hi: 300mph
Lo: 150mph
    This entry's maximum listed speed (230mph).

    Graph average of 225 miles-per-hour.
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Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units
2
2


  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.


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National Flag Graphic
Origin: United States
Year: 1976
Type: Experimental Compound Helicopter Prototype
Manufacturer(s): Sikorsky Aircraft / Lockheed / NASA - USA
Production: 2
Status: Cancelled
Global Operators:
United States (cancelled)
Historical Commitments / Honors:

Military lapel ribbon for Operation Allied Force
Military lapel ribbon for the Arab-Israeli War
Military lapel ribbon for the Battle of Britain
Military lapel ribbon for the Battle of Midway
Military lapel ribbon for the Berlin Airlift
Military lapel ribbon for the Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
Military lapel ribbon for the Falklands War
Military lapel ribbon for the French-Indochina War
Military lapel ribbon for the Golden Age of Flight
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Indo-Pak Wars
Military lapel ribbon for the Iran-Iraq War
Military lapel ribbon for the Korean War
Military lapel ribbon for the 1982 Lebanon War
Military lapel ribbon for the Malayan Emergency
Military lapel ribbon for the attack on Pearl Harbor
Military lapel ribbon for the Six Day War
Military lapel ribbon for the Soviet-Afghan War
Military lapel ribbon for the Spanish Civil War
Military lapel ribbon for the Suez Crisis
Military lapel ribbon for the Vietnam War
Military lapel ribbon for Warsaw Pact of the Cold War-era
Military lapel ribbon for the WASP (WW2)
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2
Military lapel ribbon for the Yom Kippur
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.
Measurements and Weights icon
Structural - Crew, Dimensions, and Weights:
Unless otherwise noted the presented statistics below pertain to the Sikorsky S-72 model. Common measurements, and their respective conversions, are shown when possible.

Operational
CREW


Personnel
2


Dimension
LENGTH


Feet
70.54 ft


Meters
21.5 m


Dimension
WIDTH


Feet
62.01 ft


Meters
18.9 m


Dimension
HEIGHT


Feet
14.50 ft


Meters
4.42 m


Weight
EMPTY


Pounds
20,944 lb


Kilograms
9,500 kg


Weight
LOADED


Pounds
26,048 lb


Kilograms
11,815 kg

Engine icon
Installed Power - Standard Day Performance:
2 x General Electric T58-GE-5 turboshaft engines driving a four-bladed main rotor with four-bladed tail rotor; 2 x General Electric TF34-GE-404A turbofan engines.

Performance
SPEED


Miles-per-Hour
230 mph


Kilometers-per-Hour
370 kph


Knots
200 kts

Armament - Hardpoints (0):

None.
Variants: Series Model Variants
• S-72 - Base Series Designation; two examples completed.
• S-72 "X-Wing" - Revised S-72 prototype with rigid main rotor which could be paused in flight after achieving vertical take-off; turbofan engines then handled forward thrust.