Hmmmmm.....
Since ATSM is "Acute Traumatic Stress Management," perhaps that is
off topic.

The better known "American Society for Testing and Materials (ASTM)"
is the more relevant and less dyslexic group that is developing
SLSA standards,right?



In article 41bb4fbc$1@darkstar, Mark James Boyd wrote:
I was thinking about the ATSM and JAR-22 for Special Light Sport
Aircraft.

Since SLSA are really between Standard and Experimental certificates,
applying JAR-22 in its entirety seems overregulating.

I noticed FAA US AC 21.17-2A invokes the JAR-22 standard for
gliders as 3.0kg/meter squared. This means a 1320lb standard
glider would need a 14.2 meter wingspan.

Although this does give "good" glide performance, the intent
of the Light Sport Aircraft standards are NOT good performance.
The intent is "light" and "sport."

I suggest the ATSM standard for Special Light Sport Aircraft be
less restrictive. I suggest 6.0kg/meter squared is a better figure.

This allows what is still a reasonable glide (15:1 or so), and
gives a clear distinction between airplanes and gliders.

The Diamond Katana DA-C1, which is right at the cusp between
glider and airplane, has a 7.0 kg/meter squared ratio. Yet its
glide ratio is between 12 and 14.

There are a bunch of benefits to this relaxed requirement.
One is that the resulting aircraft could have a span as little
as 11 meters. This means it can go into what have become
"airplane sized" hangars. A 14 meter wingspan just doesn't
fit in a T-hangar.

Clever designers could also make 2 meter tip extensions to be added
at the pilot discretion, to make it a 15 meter glider.
Maybe a clever way to store the extensions inside the aircraft
in a "hat rack" setup so one could motor to Minden, then
fly in wave at a wicked snot fast speed. Then land, put the
extensions on, fill up to ballast
at 1320lbs, and go thermal.

All this without having to get an airplane license. And then
fly home and put it in the hangar.

The 3.0kg/meter sq restriction is certainly a good cutoff for
high performance gliders, but for LSA, 6.0kg/meter sq results in
only a 29% reduction in span, which is critical to meet the
realities of standard hangars, but still clearly is an
industry consensus standard for a difference between gliders
and airplanes.

Otherwise JAR-22 seems pretty good as one of the
acceptable standards for LSA.

Anybody on the NTSM standards committee interested?


--

------------+
Mark J. Boyd


--

------------+
Mark J. Boyd