Sikorsky S-69

Sikorsky S-69
XH-59A
Type:	Experimental helicopter, technology carrier
Design country:	United States
Manufacturer:	Sikorsky Aircraft Corporation
First flight:	July 26, 1973
Number of pieces:	2

The Sikorsky S-69 (military designation XH-59 ) is an experimental helicopter made by the US manufacturer Sikorsky Aircraft with two coaxial rotors and two jet engines.

history

In late 1971, the Army Air Mobility Research and Development Laboratory, which later became part of the Army Research Laboratory , commissioned Sikorsky to develop the first prototype. The S-69 was a demonstrator for the Advancing Blade Concept (ABC) and was funded by the US Army , the US Navy and NASA . The first S-69 (73-21941) built flew for the first time on July 26, 1973. However, in a low-speed crash on August 24, 1973, it was severely damaged due to unexpected rotor forces and the faulty control system. The cell was then rebuilt for testing in the NASA Ames Research Center's 40 × 80 foot wind tunnel in 1979 and tested there. The second completed airframe (73-21942) flew for the first time on July 21, 1975. The test flights without turbo jets were carried out until March 9, 1977. After the two turbojets were installed, testing began on April 6, 1978, and lasted until 31 May 1980. All tests were on the testing grounds of the Applied Technology Laboratory in Stratford (Connecticut) , West Palm Beach ( Florida ) and Rentschler Field East Hartford, Connecticut. As a helicopter, the XH-59A reached a top speed of 156 kts (289 km / h), with the auxiliary turbojets 238 kts (441 km / h). The flight range has been expanded to a maximum speed of 263 kts (487 km / h; 303 mph) and a maximum altitude of 25,000 ft (7,600 m). The tests confirm the ABC concept with minor restrictions. The XH-59A, however, showed strong vibrations and had a high fuel consumption. The 106-hour test program (66 hours in helicopter configuration) for the XH-59A ended in 1981. In 1982, it was proposed that the XH-59A be fitted with advanced rotors, new engines (two GE T700s ) and a shrouded pusher propeller on the stern instead of the engines on top Change XH-59B configuration. This proposal was not implemented because Sikorsky refused to pay part of the cost. As of 2007, Sikorsky and its partners financed the development of the next helicopters using the Advancing Blade concept, the Sikorsky X2 and S-97 Raider .

construction

The Advancing Blade Concept of the XH-59A consists of two rigid counter-rotating rotors that are 30 inches apart. The counter-rotating rotors have the effect that the retreating blade stall , the stall of the retreating rotor blade, is compensated for with the leading blade of the second rotor. The very stiff rotors also prevent the rotor blades from fluttering when the rotor blade breaks backwards. With this system, there was no need to incorporate a wing for high speeds and to improve maneuverability. In addition, no rotor is required at the rear for torque compensation. The forward thrust is provided by two turbo jets attached to the side of the aircraft fuselage so that the main rotors are only required for lift. This means that the rotor speed can be reduced, which works well against the stall and flutter . A good stability against cross wind and tail wind was found. However, the installed jets lacked the power to hover outside of the ground effect . Short take-offs and landings were therefore also carried out for safety reasons .

Whereabouts of the aircraft

Airframe 73-21941 is in storage at NASA Ames Research Center and 73-21942 is in Army Aviation Museum in Fort Rucker , Alabama .

Technical specifications

Parameter	Data
crew	2
length	12.42 m (40 ft 9 in)
Rotor diameter	10.97 m (36 ft 0 in)
height	4.01 m (13 ft 2 in)
Empty mass	(9,000 lb) (11,100 lb) with turbo jets
Total mass	(11,500 lb) with low fuel and turbojets off 5,700 kg (12,500 lb) with fuel and turbojets
Max. Takeoff mass	5,000 kg (11,000 lb) with turbojets, 4,100 kg (9,000 lb) without turbojets
rotor	2 three-blade coaxial spaced 30 inches apart
Rotor speed	345 / min
Engines	2 × Pratt & Whitney J60-P-3A turbojet, 13.35 kN (3,000 lbf) each 1 × Pratt & Whitney Canada PT6T-3 Turbo Twin Pac turboshaft, 1,825 PS (1,360 kW) (or 1,500 PS)
Top speed	322 mph, 518 km / h or 263 kts (303 mph; 487 km / h) with jets [5] (184 mph, 296 km / h or 156 kts (180 mph; 289 km / h) without jets)
Cruising speed	109 kts (125 mph, 185 km / h)
Service ceiling	15,000 ft, 4,570 m (25,000 ft (7,600 m) with jets)
Rate of climb	1200 ft / min at 140 kn (6 m / s at 259 km / h)

See also

• Sikorsky X2
• Sikorsky S-97 Raider
• Sikorsky / Boeing SB-1 Defiant
• Sikorsky Raider X

Web links

Commons : Sikorsky S-69  - collection of pictures, videos and audio files

• Global Security.org Sikorsky XH-59 page
• Sikorsky X2
• "X2 marks the spot for radical rotor designs" FlightGlobal
• Leoni, Ray. The High Speed ​​Helicopter - A New Beginning (Sikorsky)

Individual evidence

1. ↑ ^{a b c d e f g h i j k l} Rudell, J. et al .: Advancing Blade Concept (ABC) Technology Demonstrator report: USAAVRADCOM-tr-81-D-5 . United States Army Research Laboratory . April 1981. Retrieved March 10, 2012. Size: 11MB.
2. ↑ ^{a b} The Fastest Helicopter on Earth . IEEE Spectrum . August 31, 2010. Archived from the original on January 30, 2017. Retrieved on August 1, 2017.
3. ↑ Felker, Fort III. NASA NASA-TM-81329, USAAVRADCOM-TR-81-A-27 Performance and loads data from a wind tunnel test of a full-scale, coaxial, hingeless rotor helicopter. http://hdl.handle.net/2060/19820004167
4. ↑ ^{a b} Robb, Raymond L. Hybrid Helicopters: Compounding the Quest for Speed  ( page no longer available ) p. 48, Vertiflite , Summer 2006.
5. ^ Rob Goodier: Inside Sikorsky's Speed-Record-Breaking Helicopter Technology . September 20, 2010. Retrieved September 22, 2010.
6. ↑ Croft, John. Hyper Helos: Prototypes coming off the drawing board and into the race , Flightglobal.com 3 July 2008. Accessed: 9 March 2012.
7. ↑ Kocivar, Ben. " Turbofan-powered flying carpet " page 68, Popular Science , September 1982. Accessed: September 2014.
8. ↑ helicopter # flight performance
9. ↑ Chandler, Jay: Advanced rotor designs break conventional helicopter speed restrictions (page 1) . ProPilotMag . September 2012. Archived from the original on July 18, 2013., Page 2 . Archived from the original on July 18, 2013., Page 3 . Archived from the original on July 18, 2013.
10. ↑ Jackson, Dave: Coaxial - Sikorsky ~ S-69 (XH-59) ABC . March 9, 2012. Archived from the original on November 6, 2014.
11. ^ ^{A b} Apostolo, G. "Sikorsky S-69". The Illustrated Encyclopedia of Helicopters . Bonanza Books, 1984. ISBN 0-517-43935-2 .
12. ↑ Bagai, Ashish. "Sikorsky XH-59A ABC (S-69)." Airliners.net, March 29, 2011. Retrieved: June 8, 2011.
13. ↑ Baugher, Joe. "1972 USAF Serial Numbers." Retrieved: June 8, 2011.
14. ↑ Stephen Harding: US Army Aircraft Since 1947 . Schiffer Publishing Ltd., Atglen, PA, USA 1997, p. 251.

• John WR Taylor (Ed.): Jane's All the World's Aircraft 1976-77 . Jane's Yearbooks, London 1976, ISBN 0-354-00538-3 .