Al Gietzen wrote:

This [403 lbs.] is not much heavier than an IO360 installation, and
I estimate the CG a couple of inches further forward than the Lyc,
resulting in a moment for the engine package that is very close to
being the same.  Definitely lighter than [an] IO 540.

Russell Kent responded:

Further forward than the IO-360 installation?  Don't you mean
further rearward? Or did you mean further forward than the heavier
IO-540 installation?

Paul Lamar responded:

It's a pusher Russell. That is the problem when people don't respond
by putting their messages at the end of the old message. From just
the Subject heading you would no necessarily know that.

No, I knew Al was referring to the pusher Velocity aircraft.  What I
don't get (and perhaps I don't understand C of G), is that making the
tail heavier (20B vs IO-360) moves the center of mass towards the tail
(i.e. "rearwards"). Center of mass and center of gravity are
essentially the same here, correct?

Russell Kent

CG of the engine or CG of the airplane? If the CG of the engine (which
is  what I think Al was referring too) moves forward so too does the CG
of the aircraft. What Al was saying (I think) is the CG of the heavier
rotary engine moves forward reducing the moment about the reference
line (usually the the nose of the aircraft) and giving the same CG
location to the aircraft.

Paul Lamar

Actually, the aircraft we were talking about is the Velocity XL-RG with the
planned installation of a Lyc IO-540K.  So the comparison was the NA 20B vs
the IO-540, not 360.

Dale

In that case I think the installed 20B will be lighter than the IO-540K.
I know my Continental O-470 is about 500 pounds.

Paul Lamar
 
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