"Terence Wilson" wrote in message
...
In the course of trying to understand how a constant speed prop works
I came across the following passage in one of the Jeppesen books:

"If the throttle is advanced without decreasing the pitch of the prop
blades to increase ___ rpm, the manifold pressure increases as the
prop mechanism attempts to keep ___ rpm constant by increasing the
blade angle. The combination of high manifold pressure and low ___ rpm
can cause damage due to high internal manifold pressures."

I found this paragraph to be confusing because it makes several
references to rpm but doesn't clarify whether it is engine or prop
rpm. The blanks were inserted by me. Can someone help me out?

Thanks in advance.

As others have said, unless you have a gearbox (not many planes do), they
are one and the same.

You may also want to ditch your Jepp book as the "theory" they are
describing really doesn't apply to most small piston aircraft. The old
"don't run oversquare" mentality which has been taught for years originated
out of military teachings that applied to very different pilots doing very
different things while flying very different aircraft. I run oversquare as
much as possible simply because it's more efficient. Many turbo engined
pilots routinely run 12" oversquare with no ill effects.

Here's an excellent group of articles that explains the principles involved
in easy to understand language:

http://www.advancedpilot.com/downloads/prep.pdf