Graviman,
My only disagreement is whether the 24CV quoted is actually 24HP.
cheval-vapeur (550 ft.lb/s)[GB] 745,6999 watt (W)
cheval-vapeur (métrique) 735,499 watt (W)
The above came from a friend in France, who coincidently co-wrote a small book on helicopters for children. This book was commissioned by Eurocopter for the celebration of 100 years of the helicopter.
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You spoke of scaling therefore the following may be of interest.
Additional Information on the Ability of the Cornu Helicopter to Hover in Ground Effect:- The Cornu Model: Leishman, in his latest article, has stated that "a model weighing up to 18 kg (40 lb) lifted by a 2 hp engine driving two contra-rotating rotors - was to make several sustained flights, in both hover and forward flight, and with many witnesses to the event." This is 20 lb/hp.
- The Flettner 282 Intermeshing: "It was capable of lifting 16 lbs. per horsepower - a figure not attained to this day by any of the modern helicopters." ["this date" - unknown]
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- The 282 had a GW of 2202 lbs and a 160 hp engine.
- The 282 had an Intermeshing configuration and this configuration has a Thrust/Power efficiency that is meaningfully below the Side-by-side configuration.
- The twin Rotor Factor for my SynchroLites and UniCopters in the Access database is 1.39 +/-. To hover out of ground effect.
- 16 lbs per hp * 1.39 = 22.24 lbs per hp. To hover out of ground effect.
- The Cornu Full-size: 573.3 lb / 24 hp = 23.89 lb/hp. Was this the GW weigh of his 13 November 1907 attempt when the craft was carrying a 121 lb sandbag?
I have answered your questions. Would you please answer mine on a previous posting.
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slowrotor,
Cornu was probably operating at a much lower tip speed.
This is very true. Leishman used the Momentum Theory, which does not consider RRPM, plus other relevant criteria.
IMHO, Leishman, appears to be very knowledgeable when it comes to conventional rotor and blade aerodynamics. However his knowledge of configurations, other than the single rotor (and tilt-rotor) appears to be minimal, at best.
Stepniewski was probably the most knowledgeable person on the pros and cons of the various rotorcraft configurations.
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The latest issue of Vertiflite, Winter 2007, has another article by Leishman entitled 'Paul Cornu and His 1907 Helicopter: A Postscript'.
Dave