Editing Contra-rotating propellers (section)

{{Short description|Two-propeller design for improving low-airspeed maneuverability}}
{{distinguish|counter-rotating propellers}}
{{About||contra-rotating marine propellers, helicopter rotors and turbine fan blades|Contra-rotating}}
[[File:Contra-rotating propellers.gif|thumb|Contra-rotating propellers]]
[[File:25 P 51XR Mustang N6WJ Precious Metal Reno Air Race 2014 photo Don Ramey Logan.jpg|thumb|300px|Contra-rotating propellers on the [[Rolls-Royce Griffon]]-powered P-51XR Mustang ''[[Precious Metal (aircraft)|Precious Metal]]'' at the 2014 [[Reno Air Races]]]]

Aircraft equipped with '''contra-rotating propellers''' ('''CRP''')<ref>{{cite journal|author1=Sasaki, N. |author2=Murakami, M. |author3=Nozawa, K. |author4=Soejima, S. |author5=Shiraki, A. |author6=Aono, T. |author7=Fujimoto, T. |author8=Funeno, I. |author9=Ishii, N. |author10=Onogi, H. |year=1998|title=Design system for optimum contra-rotating propellers|journal=Journal of Marine Science and Technology|volume=3|issue=1|pages=3–21|doi=10.1007/bf01239802|bibcode=1998JMST....3....3S |s2cid=110551942 }}</ref> '''coaxial contra-rotating propellers''', or '''high-speed propellers''', apply the maximum power of usually a single engine piston powered or [[turboprop]] engine to drive a pair of [[coaxial]] [[Propeller (aircraft)|propellers]] in [[contra-rotation]]. Two propellers are arranged one behind the other, and power is transferred from the engine via a [[Epicyclic gearing|planetary gear]] or [[Gear#Spur|spur gear]] [[Transmission (mechanics)|transmission]]. Although contra-rotating propellers are also known as ''[[counter-rotating propeller]]s'',<ref>{{cite magazine |magazine=Flight |issn=0015-3710 |author=J. M. R. |title=Enterprise in airscrews: First details of a mighty new de Havilland airscrew and the story of 21 years of achievement |url=https://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200248.html |date=March 2, 1956 |volume=69 |number=2458 |pages=237–248}}</ref><ref>{{cite conference |title=Technology and benefits of aircraft counter rotation propellers |given1=W. C. |surname1=Strack |given2=G. |surname2=Knip |given3=A. L. |surname3=Weisbrich |given4=J. |surname4=Godston |given5=E. |surname5=Bradley |conference=Aerospace Congress and Exposition |date=October 25–28, 1982 |location=Anaheim, California, USA |publisher=[[NASA]] |url=https://archive.org/details/NASA_NTRS_Archive_19830002859/page/n0}} [https://ntrs.nasa.gov/search.jsp?R=19830002859 alternate url]</ref> the term is much more widely used when referring to airscrews on separate non-coaxial shafts turning in opposite directions.