"john smith" wrote in message
...
d&tm wrote:

in my PPL training it was drummed in to me the importance of always doing
the w & b calcs with the fuel you were taking and also the zero fuel case.
I posted sometime ago that with the Warriors I flew it was impossible to
go
outside the w & b envelope by burning fuel. I have just finished my
transition to the C172 and have extensively investigated different
loading
scenarios and found exactly the same thing, at least with this N model I
am
flying.
Are there any single engine airplanes out there that really can go outside
the envelope by burning fuel? ( I am only interested in the normal
ategory - not utility). Perhaps the training is just to prepare you for
heavy aircraft?
Terry


Bonanza's come immediately to mind.
I do not know if the current models are built this way, the older models
had the fuel stored in the front of the wing, ahead of the main spar. Any
weight in the aircraft behind the front seats is behind the fuel weight.
As fuel is burned, the weight ahead of the spars decreases while the
weight behind the spar remains the same, hence the cg moves aft. At some
point, the cg moves out of the envelope (the ability of the horizontal
stabilizer to provide sufficient lift).
Piper PA32's will can also develope this situation.
Cessna's seem to have a broader range.
You have to look at each aircrafts envelope.

Van's tandem seat RV-4's had a bad string of fatal accidents until the
word got out and builders became more aware of the potential danger.

It is true that the CG moves aft with fuel burn on all of the 2 place Van's
designs. It is also true that depending on the individual aircraft and the
loading that you could run the CG beyond the aft limit. You certainly can
in my RV-6. That said, please do some fact checking before you conjure up a
"bad string of fatal accidents" for RV-4's due to CG issues. Didn't happen.
There was one accident in the NTSB database between 1980 and today where CG
was listed as a factor...

Not jumping your kimchee or anything, but facts are facts, and making 'em up
(or remembering 'em incorrectly) isn't a good idea when safety is at issue.

KB