Your article is loads better than the current one on prop effective pitch.
Vance

I just read that Effective Pitch article in EAA Sport Av and it is not
all that bad of an idea. Course it is a bit redundant with just specifying
the top speed achieved with a given prop.

It would be better if the prop building guys used a cord pitch instead
of the bottom of the blade. Also a speed specification for optimum twist.

If that seems impractical then specify the angle of the blade every
0.1 blade radii. Too many props out there with the wrong twist, improperly
twisted or no twist at all.

Perhaps the EAA could apply some pressure for standardization.

Why don't you write an article on props Vance? Send it to me first and
I will critique it :-)

Paul Lamar

I have written several propeller articles for Contact Magazine, but maybe
another one
is timely. Many of the uncertified prop builders seem to treat ptch like the
classic
" the man wants a green suit - turn on the green light" The deviation from true
helical pitch in many cases has to be measured to be believed. Sensenich has
released a lot of test data on a relatively new metal prop for 180 hp RV 6,
and it verifies what I have often stated. That is, that for a given weight,
in level flight, engine rpm is directly "keyed" to TRUE airspeed. Almost as if
it was acting as an "airscrew" as our british friends name it. This is also
true
over a wide range of altitudes both true and density. This strengthens his
concept of effective pitch, but I did not detect that level of understandig in
his article. - This is only true in those regions where induced drag is a minor
part of the total drag, which is above max climb speed - ie where most people
fly most of the time - Vance

 
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