View source for User:BilCat/Advancing Blade Concept

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[[File:XH-59 U.S. Army demonstrator.jpg|thumb|[[Sikorsky S-69]] (XH-59)]]
[[File:Sikorsky X2 World Record Speed Demonstrator RSideFront MacDill AirFest 5Oct2011 (14513000689).jpg|thumb|[[Sikorsky X2]]]]
[[File:Sikorsky–Boeing SB-1 Defiant (cropped).jpg|thumb|[[Sikorsky–Boeing SB-1 Defiant]] ]]

The '''Advancing Blade Concept''' system consisted of two rigid, contra-rotating rotors (30 inches apart)<ref>Kocivar, Ben. "[https://books.google.dk/books?id=FzCnbu4xM0YC&printsec=frontcover&source=gbs_ge_summary_r&redir_esc=y#v=onepage&q=abc&f=false Turbofan-powered flying carpet]" page 68, ''[[Popular Science]]'', September 1982. Accessed: September 2014.</ref> which made use of the aerodynamic lift of the advancing blades. At high speeds, the retreating blades were offloaded, as most of the load was supported by the advancing blades of both rotors and the penalty due to [[Retreating blade stall|stall of the retreating blade]] was thus eliminated.<ref name=ppm2012>Chandler, Jay. "[http://www.propilotmag.com/archives/2012/September%2012/A3_Rotor_p1.html Advanced rotor designs break conventional helicopter speed restrictions (page 1)] {{webarchive |url=https://web.archive.org/web/20130718171642/http://www.propilotmag.com/archives/2012/September%2012/A3_Rotor_p1.html |date=July 18, 2013 }} " [http://www.propilotmag.com/archives/2012/September%2012/A3_Rotor_p2.html Page 2] {{webarchive |url=https://web.archive.org/web/20130718141528/http://www.propilotmag.com/archives/2012/September%2012/A3_Rotor_p2.html |date=July 18, 2013 }}  [http://www.propilotmag.com/archives/2012/September%2012/A3_Rotor_p3.html Page 3] {{webarchive |url=https://web.archive.org/web/20130718141548/http://www.propilotmag.com/archives/2012/September%2012/A3_Rotor_p3.html |date=July 18, 2013 }}. ''ProPilotMag'', September 2012. Accessed: 10 May 2014. [https://web.archive.org/web/20130718171642/http://www.propilotmag.com/archives/2012/September%2012/A3_Rotor_p1.html Archive 1] [https://web.archive.org/web/20130718141528/http://www.propilotmag.com/archives/2012/September%2012/A3_Rotor_p2.html Archive 2]</ref><ref name=uniS69>Jackson, Dave. "[http://www.unicopter.com/0891.html Coaxial - Sikorsky ~ S-69 (XH-59) ABC] {{webarchive |url=https://web.archive.org/web/20141106044105/http://www.unicopter.com/0891.html |date=November 6, 2014 }}" ''Unicopter'', 9 March 2012. Retrieved: 22 May 2015. [https://web.archive.org/web/20141106044105/http://www.unicopter.com/0891.html Archived] on 6 November 2014.</ref> This system did not require a wing to be fitted for high speeds and to improve maneuverability,<ref name=radcom>J. Rudell et al. [http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA100181 Advancing Blade Concept (ABC) Technology Demonstrator report: USAAVRADCOM-tr-81-D-5], ''[[United States Army Research Laboratory]]''<!--not sure-->, April 1981. Size: 11 MB. Accessed: 10 March 2012.</ref> and also eliminated the need for an anti-torque rotor at the tail.<ref name=Apostolo>Apostolo, G. "Sikorsky S-69". ''The Illustrated Encyclopedia of Helicopters''. Bonanza Books, 1984. {{ISBN|0-517-43935-2}}.</ref> Forward thrust was provided by two turbojets, which allowed the main rotor to only be required to provide lift. It was found to have good hover stability against crosswind and tailwind. With jets installed, it lacked power to hover out of ground effect and used [[STOL|short take-off and landing]] for safety reasons.<ref name=radcom/><!--p215-->

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==References==
===Notes===
{{reflist}}

===Bibliography===

==External links==
* [https://www.sikorskyarchives.com "The High Speed Helicopter" article on the Sikorsky Archives]

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