A214395 Decimal expansion of 16/27.

5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5, 9, 2, 5

Offset: 0

Author

Charles R Greathouse IV, Aug 07 2012

Keywords

• nonn
• easy
• cons

Comments

Betz's constant (or Betz's coefficient): maximum efficiency of a turbine. The constant is unfortunately named; Lanchester discovered it before Betz, and Lanchester cites Froude (though it seems that Lanchester was the first to write it explicitly). Joukowsky (also spelled Zhukovsky) and Munk published discoveries the same year as Betz.

Examples

			0.5925925925925925925925925925925925925925925925925925925925925925925...
		

References

• Albert Betz, "Das Maximum der theoretisch möglichen Ausnutzung des Windes durch Windmotoren", Zeitschrift für das gesamte Turbinenwesen 26 (1920), pp. 307-309.
• N. E. Joukowsky (Николай Егорович Жуковский), Windmill of the NEJ type (in Russian), Transactions of the Central Institute for Aero-Hydrodynamics of Moscow (1920). Appeared in Collected Papers Vol VI, The Joukowsky Institute for AeroHydrodynamics, Moscow, Russia (1937); VI: 405-409 (in Russian).
• F. W. Lanchester, A contribution to the theory of propulsion and the screw propeller, Transactions of the Institution of Naval Architects 57 (1915), pp. 98-116. (See pp. 114-115.)

Links

• Albert Betz, The Maximum of the Theoretically Possible Exploitation of Wind by Means of a Wind Motor, Wind Engineering, Vol 37, Issue 4, 2013 (English translation).
• Max M. Munk, Wind driven propeller, NACA Technical Memorandums 201 (1920), pp. 1-12 (German original in: Zeitschrift für Flugtechnik und Motorluftschiffahrt August 15, 1920: 220-223)
• Henry Reich, Windmills Are NOT Like Dams, minutephysics video (2022).
• Index entries for linear recurrences with constant coefficients, signature (0,0,1).

Crossrefs

Cf. A021031, A021112.

Programs

Mathematica

RealDigits[16/27,10,120][[1]] (* or *) PadRight[{},120,{5,9,2}] (* Harvey P. Dale, Dec 04 2012 *)

PARI

16/27.

Formula

Equals 16 * A021031. - Felix Fröhlich, Jun 17 2017