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

Exactly; thank you.  Sorry I wasn't more clear.  With the CG of the engine
package further forward (closer to the firewall in the Velocity) the CG of
the airplane remains in about the same place, even though the engine package
is a bit heavier.

And the additional 60-70 hp over the IO 360 should increase speed by about
10%, or about 18 kts for the standard RG.

Al Gietzen

 
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