DmitriKozlowsky Posted November 10, 2021 Posted November 10, 2021 How does UH-1H slip indicator knows relative wind? Where is the weather vane or anemometer? In Gazelle there is a high tech , but 99.99% reliable instrument. A peice of string. Jet age technology stolen from F-14A development. In KA-50 there is a mechanical weather vane on nose pitot. A triumph of Russian space age engineering. On AH-64, AH-1W/Z there is anemometer. I see no such devices on top pitot tube on our UH-1H. Yet the turn and slip indicator is working great.
razo+r Posted November 10, 2021 Posted November 10, 2021 (edited) It doesnt show relative wind, it shows if you are coordinated or not, slipping or skidding. https://en.m.wikipedia.org/wiki/Turn_and_slip_indicator Edited November 10, 2021 by razo+r
admiki Posted November 10, 2021 Posted November 10, 2021 Slip indicator is powered by gravity. If you are flying straight and level and in trim, gravity pulls straight down. So ball goes to the bottom of that curved tube. If you are flying straight and level but out of trim, that means you must be banked towards direction of travel. Now gravity pulls to the side and ball follows. That's simplistic explanation. More detailed explanation will involve force vectors. When turning, in coordinated turn you have lift vectors going up and to the side of bank and weight going down (gravity) and out of the turn (inertia). Resultant forces are lined straight up and down through helicopter vertical axis, and "new" gravity is pulling straight down for you inside helicopter. Hence, the ball stays in centerm regardless of bank.
DmitriKozlowsky Posted November 10, 2021 Author Posted November 10, 2021 That means I am hosed, and have been, and not known it all these years having this module. I thought that when landing or in stable hover, when the needle is straight up, that means the nose is pointed into wind. I never made use of popped smoke or wind socks. I used chimney smoke , when visible, as guide as wind direction.
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