Fixed & Rotary Wing Comparison by Louis Breguet

kolibri282

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In the paper below Lois Breguet, world famous French air- and rotorcraft designer, presents a comparison between a fixed wing and a rotary wing aircraft and concludes that the fixed wing will have a much lower payload and shorter range. This is quite a surprise to say the least:
https://gallica.bnf.fr/ark:/12148/bpt6k9795806s/f77.item.r=autogire

Some of the advantages for the rotorcraft seem to come from the fact that for the fixed wing no flaps or other high lift devices are considered. Nevertheless I am really looking forward to the comments by the experts.
 
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Tyger

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I see that was published in 1935. He claims he did research on rotary wings in 1905-1906, but then apparently lost interest until Cierva's machine appeared. :sneaky:
He makes an interesting comment about the word hélicoptère vs gyroplane (made before what we call helicopters existed), as distinct from Cierva's "autogyre", with its unpowered rotor.
 
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Doug Riley

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Breguet built a helo in the 20's, IIR. No helicopter of that era was successful, although some flew in ground effect.

It took awhile, and the arrival in the field of people with serious mathematical chops (such as Cierva) to get a handle on what makes a rotorcraft tick.

The inescapable efficiency limitations of rotary wings were clear by the time the successful ones flew in the late 30's. For some missions, these shortcomings are worth tolerating. For other missions, they're not.
 

Jean Claude

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Thanks for sharing, Juergen.
I do not see the date of this communication
In this paper, Louis BREGUET compares an FW aircraft to an RW aircraft, probably before the tests of his Helicopter BREGUET-DORANT:
Sans titre.png
With which
  • 14 December 1935: Closed-circuit flight with 500 m diameters
  • 26 September 1936: Height of 158 m
  • 24 November 1936: Flight duration of 1:02:50 hours over a 44 km closed circuit at 44.7 km/h
  • Maximum speed 120 km/h
His comparison assumes a forward speed of 100 m/s (224 mph) for which he writes that the advancing blade tip would be 1.91 times higher, i.e. without still concern for compressibility (last page)
But he had failed to consider the stall of the retreating blade, when this Mu factor is 1.1
The airfoil attacks the air from the trailing edge !
 
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