Question for those who understand helicopter aerodynamics...
I am somewhat savvy on helicopter dynamics, having been flying the R/C versions since 1982, but there is one thing I haven't been able to figure out...
Quite a few full-scale helos, including but not limited to the UH-60 Blackhawk, have tilted tail rotors. Why? What is the reasoning behind this "feature"?
____________________________ Bill R. North Alabama
_____________________________ I just can't quit grinnin' from all of this winnin'!
November 11, 2019, 05:29 PM
benny6
...This message has been edited. Last edited by: benny6,
tailrotor authority determines hovering performance at altitude.
November 11, 2019, 10:44 PM
bushpilot
I have mostly owned/flown Bell aircraft and Sikorsky S-76 and Aerospatiel SA-15. Can't really answer your question directly but it may be the lift mentioned above.
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But to answer, the moment (tilting force and yaw in a forward pitch and lateral roll) induced by the main rotor torque, is offset with angled tail rotor. It is sort of like trimming a fixed wing aircraft. (Or as some recip aircraft had offset in the engine mounting to help counteract the torque and asymmetrical thrust.)
"the meaning of life, is to give life meaning" ✡ Ani Yehudi אני יהודי Le'olam lo shuv לעולם לא שוב!
November 12, 2019, 01:05 AM
V-Tail
quote:
Originally posted by sigmonkey:
some recip aircraft had offset in the engine mounting to help counteract the torque and asymmetrical thrust.
Yup. The V-Tail's engine centerline is not parallel to the airplane's longitudinal axis, for the reasons that you cite. It is offset so that the thrust provides a slight yaw to starboard, to counter the port yaw produced by P-factor and torque.
הרחפת שלי מלאה בצלופחים
November 12, 2019, 05:35 AM
HayesGreener
I know nothing of helicopter dynamics. Flew all over Southeast Asia in the things and see them flying every day from the Navy training base nearby, but the more I look at them, the more mystified I am. I am convinced there is an element of black magic involved.
Yeah, yeah.... I know. Helicopters do not fly; they beat the air into submission!
quote:
Originally posted by sigmonkey: -fixedwingaircraftmaintenancemonkey
But to answer, the moment (tilting force and yaw in a forward pitch and lateral roll) induced by the main rotor torque, is offset with angled tail rotor. It is sort of like trimming a fixed wing aircraft. (Or as some recip aircraft had offset in the engine mounting to help counteract the torque and asymmetrical thrust.)
Thanks... that makes sense!
____________________________ Bill R. North Alabama
_____________________________ I just can't quit grinnin' from all of this winnin'!
