Talk:Cierva W.11 Air Horse

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Length, width and rotor diameter? Picture measured and calculations done[edit]

https://en.wikipedia.org/wiki/Cierva_W.11 says length = 88 ft 7 in (27.00 m) ... seems to be from a German source rotor diam. = 95 ft 0 in (28.96 m) ... rather English source nominated source: Donald, David (editor) (1997). The Encyclopedia of World Aircraft. Leicester, UK: Blitz Editions. ISBN 1-85605-375-X. p262 Q1: Length means length of fuselage alone?

but: https://de.wikipedia.org/wiki/Cierva_W.11 tells Länge (über die Rotorspitzen) = Lenght over tips of rotor blades = 27,00 m (88 ft 7 in) Spannweite (über die Rotorspitzen) = Width over tips of rotor blades = 29,00 m (95 ft) Q2:

Interpreting the only picture https://commons.wikimedia.org/wiki/File:Cierva_W.11.jpg I make out an entrance door git by the shadow of a blade of the front rotor. Lets say its 1,50 m high, than I estimate the fuselage to be 10 times as long, which is 15 m. Accordingly the rotor diameter could be as well about 15 m. So de.WP width (over tips) = 29 m makes sense. And the rotor diam. in en.WP must be wrong.

I will correct. -- I do expect that all rotors have the same diameter. In the picture luckily 2 blades - one of the front and one of the right rear rotor - nearly point to each other as you can see on the nearly equal (projected) length of the relative two other blades. And we see that situation pretty perpendicular, because from the sight line of the third rotor axis. The blades tips distance is measured about 5 % the distance of the two rotor axes.

Assuming the same narrow distance between the two back rotor circles, and accepting the data for width as 29.00 m = 205 % rotor diameters

then rotor diam. = 29 m / 2.05 = 14.15 m

and rotor circle distance = 29 - 14.15*2 = 0.70 m

rotor axes distance = 14.15 + 0.70 = 14.85 m

3 axes in a (horizontally) equilateral triangle assumed:

distance of front rotor axis to the line connecting the two back rotor axes = 14.85 m * sqrt (3) / 2 = 12.86 m

https://de.wikipedia.org/wiki/Wurzel_3

Length over blade tips of the the 3 rotor circles is then:

Length over tips = 12.86 + 2/2*rotor diam. = 12.86 + 14.15 = 27.01 m

makes sense and correlates with the data in de.WP plausibel with the picture, that the fuselage is not protuding the back rotor tips in length.

RESULTS: A. the verified data are:

width over blade tips = 29.00 (or 28.94) m

length over blade tips = 27.01 (or 28.95) m

B. from measuring the blade tips distance in the picture calculated date are:

rotor diameter = 14.15 (14.12) m

rotor circle distance = 0.70 (0.70) m

rotor axes distance = 14.85 (14.82) m

C. error estimation :

rotor circle distance (assumed as high as) +/- 40%

rotor diameter (derived from fixed width) +/- 1% ... only, fine! --Helium4 (talk) 15:27, 9 February 2014 (UTC)[reply]

the above calculations turn out out to be a quite good verification of the rotor diameter, already written in the English article: 14.33 m which is 1.01% more than I calculated (14.15 m +/- 1%) ... very nice : )

That lets the rotor circle distance be only 0.30(5) m (= 56% less than 0.70 m)

I did not read the last line in the English table earlier.

the misunderstanding arose from an not fully flexible table format:

|span main= 95 ft 0 in ^[1]

|propeller or rotor?=rotor

gives the wrong print-out "Rotor diameter 95 ft" which is only true if there are NOT 2 transversal rotors - indeed a very special, pretty seldom case ...

is it possible to override the printout "Rotor diameter 95 ft" by "Width, rotors turning 95 ft" ?

I did not read the footnote, although it even pops up per mouse-over, as I concentrated to the first discrepancy between the English and the German article. I should have better supplied me with a better overlook ... that is my part ... --Helium4 (talk) 16:23, 9 February 2014 (UTC)[reply]

95 ft is overall width, with rotor diameter of 47 ft. The Air Horse with its unique layout seem specifically designed to confuse templates. I've switched the specification templates to make it more obvious.Nigel Ish (talk) 16:31, 9 February 2014 (UTC)[reply]

References

^ Width rotors turning.

[1] Width rotors turning.

[1]