B307

DESIGN: UniCopter ~ Fuselage - Tail

Outside Helicopters

Hughes H500

The Hughes H500 helicopter have a 'T' tail; (high horizontal stabilizer outside of the main rotor's down wash.)

Mini 500:

The Mini 500 has a 'T' tail. "Minis .... often showed a strong negative pitching action on the power cut ...... especially ... at successively higher speeds."

UniCopter

Miscellaneous:

Removable tail, for transportation ~or~ better yet just lower the tail and raise the nose when in the trailer.

The T-tail is considered structurally inefficient because of the higher overall weight of the vertical fin required to carry the stabilizer loads and also be cause of the various low frequency structural vibration modes that can be excited by the main rotors. The forgoing is somewhat reduced since there is no tail rotor.

Consider the idea of having a single boom at the rotational axis of the propeller. The propeller could be mounted to the fuselage and driven by a planetary arraignment where the sun gear is quite large and the planetary gears are quite small. The planet gear holder would be stationary and the engine would drive the sun gear via a flexible coupling.

Possibly Relevant Outside Web Pages:

Langley Tech Report:

S. A. Gorton, J. F. Meyers and J. D. Berry, Velocity Measurements Near the Empennage of a Small-Scale Helicopter Model , American Helicopter Society Forum 52, Washington, DC, June 4-6, 1996, pp. 15, (2MB). Format(s): Postscript, or PDF

The following one appears to be the same.

Susan Althoff Gorton, John D. Berry, W. Todd Hodges and Deane G. Reis, Flow Environment Study Near the Empennage of a 15-Percent Scale Helicopter Model , NASA/TP-2000-210085; AFDD/TR-00-A-004, March 2000, pp. 30, (2MB). http://techreports.larc.nasa.gov/ltrs/dublincore/2000/tp/NASA-2000-tp210085.html Have hard copy. Is based on the Comanche, which has a 'T' tail where the HS is at the same elevation as the main rotor.

57. Exploratory Investigation of Aerodynamic Characteristics of Helicopter Tail Boom Cross-Section Models With Passive Venting
Daniel W. Banks; Henry L. Kelley
NASA Langley Research Center
NASA/TP-2000-210083, AMCOM-AFDD/TR-00-A-007 , June 2000; 20000620
Two large-scale, two-dimensional helicopter tail boom models were used to determine the effects of passive venting on boom down loads and side forces in hovering crosswind conditions. The models were oval shaped and trapezoidal shaped. Completely porous and solid configurations, partial venting in various symmetric and asymmetric configurations, and strakes were tested. Calculations were made to evaluate the trends of venting and strakes on power required when applied to a UH-60 class helicopter. Compared with the UH-60 baseline, passive venting reduced side force but increased down load at flow conditions representing right sideward flight. Selective asymmetric venting resulted in side force benefits close to the fully porous case. Calculated trends on the effects of venting on power required indicated that the high asymmetric oval configuration was the most effective venting configuration for side force reduction, and the high asymmetric with a single strake was the most effective for overall power reduction. Also, curves of side force versus flow angle were noticeable smoother for the vented configurations compared with the solid baseline configuration; this indicated a potential for smoother flight in low-speed crosswind conditions. /
ftp://techreports.larc.nasa.gov/pub/techreports/larc/2000/tp/NASA-2000-tp210083.ps.Z
http://techreports.larc.nasa.gov/ltrs/PDF/2000/tp/NASA-2000-tp210083.pdf
Updated/Added to NTRS: 2004-12-08

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Last Revised: February 14, 2005