Weight and Balance

[george@t...]

Ok,

I finally did the Weight and Balance that I should have done last
October...Hey I knew that it would fly...It did... :-)

My empty weight is 400lb and the cg is at 22% of chord with me in the plane
24% if I take a 150lb passenger. I'm 5'8" and 235lb. I don't have any
paperwork to tell me what the flight envelope is for this wing.

Does anyone know what the forward most and aftmost cg limits are for the 24
foot Gull J2 wing?

George

[Jim C]

George,

I show the CG should be between 72"-78", however, if I were you I
would call Mark Beierle to be sure.

Jim C

[george@t...]

Thanks Jim,

But I'm looking for the cg envelope in percentage of chord length. You say
72 - 78 inches, but I don't know what your datum point is.

72 - 78 inches from what? It's the percentage of wing that matters. That
way, it doesn't matter what fueselage or other stuff you have on the
aircraft.

George

[Jim C]

I looked all through the manual and could find no reference to this
at all.

I use the nose of the aircraft as my datum (FYI).

> 72 - 78 inches from what? It's the percentage of wing that matters.

I'm not that famaliar with the % of wing method. I can give you the
datum off the leading edge of the wing though - It is 15-21" for
allowable flight range. Now how that equates to percentge is beyond
me and more engineerish than my small brain allows for. I checked
with some others around here about this since I am kind of stupid in
this methodology and unfortunately all I got back was blank stares,
so it looks like I am not totally alone here. Sorry I was not able to
help out here.

> That way, it doesn't matter what fueselage or other stuff you have
> on the aircraft.

Really - this doesn't seem right to me. Where can I find info on
this? It sounds interesting.

Jim C

[george@t...]

Jim,

A wing is designed to fly with it's center of gravity within some range of
the percentage of chord length. If I assume that your wing is the same as
mine, then the chord length is 55.75 inches.

So if you are saying that the acceptable range is 15 - 21 inches then that
equates to 27% - 37.6% of chord length.

As far as the other stuff goes. The length of the fuselage, tail, mains,
battery, BRS... any of that only matters from a gross weight standpoint. The
key for a flying wing is where it's cg is while flying relative to the
design of the wing and the acceptable envelope for the wing.

And you are saying that that envelope for the 24 ft wing is 15 - 21 inches
or 27% - 37.6% of chord. Thanks for the info.

George