Sideways engine?

[george kennie]

Just a little additional input here. This off-set to the left thing
doesn't seem to me to be as pronounced as many seem to be implying. My
Hyde type mount is 1/2"off center on the firewall, but the buggar is
almost  an inch thick and the engine doesn't sit up against the puck to
allow line clearance, so at that distance from the firewall the
off-center distance is less than 3/8" which puts almost 2&3/4" of the
shaft to the right of center. Now I grant you that the segment to the
left of center is heavier, but by how much? The whole shaft weighs 5.6
ounces.If we say that 3/4 of the weight is to the left of center, then
there is 4.2 ounces left of center and 1.4 oz. to the right of
center.Don't forget that this monster has a spinner and a prop bolted to
it's long end and they total somewhere in the neighborhood of 7 ounces.
Let' see now 7 plus 1.4 equals 8.4 ounces right of center and 4.2 ounces
left of center.Hmmm,....Oh yeah, lets not forget that there's a header
contributing to the picture also. Its hanging off  the left side of  the
aircraft and it weighs 1.2 ounces, so now we have 5.4 on the left and
8.4 on the right, so we've narrowed it down to only a 3 ounce
differential.Now I really don't know if it affects our execution of
snaps or tight high-G corners, but I think that the  aircraft  is still
in a state of dynamic imbalance. I think that I can come awfully close
by statically balancing, but is it perfect? I don't think it's even
close.And I also think that if you could fly an aircraft that was in
perfect dynamic balance, you would really be able to tell the difference
and it wouldn't take someone with the ability of a Troy to be
overwhelmed with awe.
I remember when setting up my first Heli that the instructions
emphasized balancing the blades, and they didn't want you to just hook
up the blades to the blade holders and the shaft and balance the whole
thing as a unit, but the individual blades were to be balanced against
each other to be absolutely certain that the balance point was at
exactly the same distance out on each blade. Otherwise the dynamics
would be off, even though the head, as a unit, was in balance.
Just a little more grist for the mill.
Georgie

Bob Pastorello wrote:

> Nat, I'd tend to agree - the moment arm of the mass offset is so
> minimally-different from a conventional inverted motor.  Actually,
> some mass moment would actually move CLOSER to longitudinal centerline
> with a side-mounted motor, thus reducing the dynamic imbalance.  As
> someone else pointed out, we statically-balance with a mass offset
> left of center.    How little difference could there actually be?
> Maybe tenths of an ounce in moment?
> Bob Pastorello, Oklahoma
> NSRCA 199, AMA 46373
> rcaerobob at cox.net
> www.rcaerobats.net
>
>      ----- Original Message -----
>      From: Nat Penton
>      To: discussion at nsrca.org
>      Sent: Wednesday, January 14, 2004 9:02 PM
>      Subject: Re: Sideways engine?
>       If lateral balance is attained with assymetric weight
>      distribution then the plane would be dynamically unbalanced,
>      that is there would be assymetric forces during accelerated
>      roll . I suppose this might be noticeable with significant
>      assymetric weight distribution, but probably not with what
>      we are talking about. Mike Nauman where are you ?
>
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