Re: REFLECTOR: Engine weights

[Peter Beaty <PETER.J.BEATY@usa.dupont.com>]

At 05:24 PM 10/13/98 -0400, Carl Hoffman wrote:

>Peter,
>Didn't you mean some like:
>
>IO-360    320.4 lbs    24.2 inches from firewall.
>I0-540    396.4 lbs    28.2 inches from firewall.
>FRANKLIN  318.4 lbs    24.4 inches from firewall.
>MAZDA     430.2 lbs    19.4 inches from firewall.
>CHEV V6 Alum block
>etc, etc
>
>In other words the weight of the engine and the c.g. of the engine from
>the firewall. The empty weight of the plane depends on a lot more things
>than the weight of the engine. I think your interested on knowing the
>effect of hanging different engines on the same plane.
>
>Carl Hoffman
>


Yep, this is what I meant.  Simon is correct in stating that weights & c.g.
vary from builder to builder, and that Velocity's way of measuring c.g. is
from the nose.  However, it would be useful to know the effect of hanging
different engines on the same airplane; the point of attachment is the aft
face of the firewall.  

What I should have asked for is weight and moment arm from the firewall,
where the moment arm is measured from the firewall to the c.g. of the
engine.  Carl lists some interesting numbers, which I take to be bare
engine weights & moment arms.  It would be useful to have similar info for
the complete engine package (with all accessories) and moment arm [yes, I
know lightweight starters; one vs two mags; etc., all make a difference!].

Using Carl's info for the bare engines,  and using the IO-360 as base case,
the differences in weight and moment arm are:

         MOMENT ARM      DIFFERENCE      DIFFERENCE IN
           lb-in         IN WT, lbs      MOMENT ARM, lb-in

IO-360      7754            0
IO-540     11178          +76             + 3425
Franklin    7769          - 2             +   15      
Mazda       8346         +110             +  592

There is little difference between the Franklin and the IO-360, but a big
difference going to the IO-540.
I "assume" Mazda means the 3-rotor (20B?) engine??

Any othere input?

Pete Beaty.