REFLECTOR: MODIFICATIONS

Dave Black dvblack at comcast.net
Sun Jan 2 14:18:30 CST 2005


> Tom,


> I am suspecting my safe
> envelope would be similar to other Elite RGs ... but the extra
> weight in the back would no doubt have an effect.

Your safe CG range should be IDENTICAL to all other LongWing Elites. Your
engine will not change that. The addition of your heavier engine farther aft
simply means your particular plane will be more tail heavy. 

On my shortwing RG (not yet flying) the CG will be at aft limits with a single
pilot, and at forward limits with two up front. That's just how big the CG box
is. The rear seat has nearly no effect on CG. With your additional aft weight
and CG, you will need to load equipment or ballast forward in order to keep
the CG safe while flying alone. You might want to move the battery farther
forward. 

As far as finding out for certain what your specific CG and weight range is,
that should be done during flight testing. Load the plane toward different
corners of the CG box and see how it performs at various speeds and
configurations. Gradually expand the range in all directions. Have a way of
changing CG during flight in the event you reach an uncontrollable
configuration. 

As I understand it, of the two CG limits the aft limit is the more dangerous.
While forward CG will reduce elevator authority, exceeding aft CG makes a deep
stall possible. Just a gut feeling: Your plane is unlikely to exceed forward
CG in any normal loading situation. But you need to be very careful with your
aft CG. If CG is out of the aft limits the plane will fly beautifully right up
until it goes into a deep stall.



We once owned a Cardinal RG. Before purchase I noticed at least half of these
had nose gear damage history. Turns out it was not a defect in the nose gear,
but in the CG. The plane is right at forward CG with a single pilot, and can
exceed forward CG with two up front. After doing some W&B calculations, I
found that a single 100 pound pilot flying with 20 gallons of fuel could load
the entire remaining legal weight flush against the aft cargo bulkhead and
still be within aft CG limits. There was simply NO way to load this plane out
of aft CG without also loading it beyond weight limits. 

When we bought our V35-B Bonanza, I found the exact opposite. In that plane
you could load virtually the entire useful load under the pilot's feet and
never exceed forward CG. Aft CG was very easy to exceed, however -- especially
with that huge cargo area. 


Dave Black
Shortwing RG


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