Just guessing, but I'd bet that the FAA got its numbers from the
manufacturer. When I was looking for moment arms for my ASW-19, the
best source turned out to be the TCDS and not the flight manual. An
email to Schleicher confirmed that the FAA numbers were correct for
the 19.

Is there any chance that your Operating Limitations letter was
"adopted" from a ketter fir an earlier model of the LS1? Would the max
gross and the Vne you quoted be correct for the first version?

-John

rlovinggood wrote:
My glider has an old Experimental Operating Limitations letter from
the FAA, dated 16 APR 1980. Among other things, it states:

"No person may exceed the designer's or builder's recommended limits
as follows: Maximum gross weight 1,100 lbs..."

Eleven Hundred Pounds? Where did that come from??? My aircraft
manual states the maximum weight of 752 lbs for my LS1-d. NOT ELEVEN
HUNDRED POUNDS!

The Operating Limitations continue,
"...And maximum airspeed in smooth air 121 knots..."

Back to the aircraft manual, the limit is 130 knots.

Why would the FAA, back in 1980, have different limits than the
manufacturer? How could they come up with a weight that is almost 1.5
times greater than what LS said? At 752 lbs, my wing loading (using
9.75 sq meters = 104.95 sq. ft) is 7.2 lbs/sq.ft. and at 1,100 lbs,
the loading is 10.5 lbs/sq. ft.

Don't worry, I don't fly with water and I'm not going over 752 lbs.
Just wondering if anyone might know where the FAA found their numbers.

Thanks,
Ray Lovinggood
Carrboro, North Carolina, USA