wrote:

On Sat, 27 Aug 2005 21:02:11 GMT, Gord Beaman
wrote:

Max Richter wrote:

Hallo,

i am wondering why American aircraftradialengines have no aerodynamical
spinners.Airplanes with inlineengines like P51;P40;P38 and so on have
aerodynamical optimized spinners.
And German radialengines had spinners like the FW190.Zero´s and other
Japanese aircraft had them.
What is the reason why the wellbuild American aircraft had just a little
hup on their propellers.
Thank You and greetings
Max

I think that the reason is that because of the comparatively
large frontal area of most radial engines that a spinner is sort
of superfluous...IOW. the airstream is backed up well in front of
the prop hub therefore it 'makes it's own cone' in front of the
prop hub therefore a spinner on the prop hub would serve little
or no useful purpose...besides, you don't want the air to be
scooted outside the cylinders so what purpose could a spinner
provide? I'm open to other opinions...what say?...


(The small hub is necessary to contain the prop pitch change
mechanisms BTW...)

And on second thought the Beechcraft C-45 (Expeditor) does have
small spinners on their props...FWIW

They were probably not worth much. The Bugsmasher (a/k/a the
Smugbasher, a/k/a the SNB, a/k/a the C-45) was not exactly a high
speed aircraft. Some civilian versions of the Beech 18 were rather
quick (for their time) but still were 150-170 kt. aircraft (at the
outside).

The cost to fashion an aerodynamic "spinner" probably was not worth
the increase in performance.


But wouldn't it be self defeating to do that?...if you made them
large enough to give you much of an increase in speed then
wouldn't they deprive the cylinders of enough cooling
airflow?...seems to me that they could have gained aerodynamic
efficiency by placing the prop further forward and then narrowing
the frontal air intake with cowlings. I suspect that they need
all the cooling that they now have (IOW, they're designed that
way)

The S2, with which I am very familiar, had just plain, old hubs. :-)

Bill Kambic

So did the Argus with which I'm very familiar too...

--

-Gord.
(use gordon in email)