Ed wrote:
>Just a little addendum...the prop pitches also came out of just about
>every engine that GE or Pratt & Whitney ever built, not just from the
>WW2 era. All the DC series up to the DC7, the Old Constallations, just
>about any military recip built up until right now, and of course, the
>civilian versions of any multi-engine aircraft. US FARs require that
>a "means be available to rotate the propeller to a 90 degree position
>in the event that engine fails." Don't take that as an exact quote..
>
I'd heard that modern prop pitch actuators are mostly hydraulic, so the
supply of electric motors may be limited.
Little cousin from the WW2 era was the cowl gill motor, which is a
similar cylindrical epicyclic unit, but much smaller, originally
intended for opening and closing the cooling slats on aero engines.
It's too small for HF beams, unless you use it to drive through a car
starter reduction gear. If the diameter and weight are not a problem
(eg if you rotate the whole tower from ground level) starter gears and
flywheels are a nice cheap way to generate a lot of torque and braking
power.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
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