On Tue, 14 Sep 2010 21:28:39 -0500, Comrade technomaNge
wrote:

On 09/14/2010 05:37 AM, J. D. Slocomb wrote:

As a general statement two speed superchargers were designed to give
max rated boost in low speed for takeoff, i.e. ~ sea level, while the
high speed was used at altitude. At least that is how the radial
engines were designed. After the advent of turbos, I don't believe
that two speed superchargers were used to any extent. At least the
C-97, which as far as I know, was the last strategic reciprocating
engine airplane used by the A.F. had a single speed supercharger and
turbos.

The procedure for shifting to high blower, by the way, involved
throttling back a bit, to prevent over boosting, shift to high speed,
and then reset throttles for desired manifold pressure.

Cheers,

John D. Slocomb
(jdslocombatgmail)



John, did you fly on C-97s? I worked on a fleet
of Biscuit Bombers when I was stationed in Guam.


technomaNge

Nope, engine mech. C-97's at Bangor, Maine, B-50's and B-29's before
that. When the C-97's finally phased out I changed career fields. I
liked working on airplanes o.k., just not the 24 hours a day that SAC
demanded.
Cheers,

John D. Slocomb
(jdslocombatgmail)