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Posted for Sky2high@aol.com:
Maybe this can help Lancairians understand some high insurance premiums. I
noticed a Kitplane's article "The Safe Homebuilt", available on their
website. You may find that it makes interesting reading.
http://www.kitplanes.com/magazine/pdfs/1004-3335.pdf
I have extracted the following text from the article:
……….
As the vice president in charge of homebuilt insurance at Avemco, Jim
Lauerman cites two primary gauges for homebuilt safety. The first is wing
loading. Wing loading is calculated by taking the maximum gross weight of the
airplane and dividing that number by the number of square feet of wing area.
For
homebuilt airplanes, wing loadings can vary from 10 pounds per square foot
for a
Kitfox, to 15 pounds per square foot for an RV-7, to 33 pounds per square
foot for a Lancair IV-P. Wing loading is often used in preliminary design
calculations to predict landing speeds. In Lauerman’s experience, wing
loading is
directly proportional to severity of loss.
The second criterion Lauerman uses is how well tested a design is. For
example, the Van’s Aircraft RV-6 is a well known and well tested design. If
a new
design comes from a manufacturer with a good track record, such as Van’s new
RV-10, that manufacturer’s track record counts, too.
Beyond those two primary criteria, there are issues of low-speed handling
qualities and longitudinal stability. It also helps if the plane was
designed
by real engineers. Lauerman says that you can look at the distance from the
c.g. to the tail and the size of the tail, and just from that you’ll be able
to
tell something about the aircraft’s handling. Also important as a predictor
of safety is how well the plane conforms to the manufacturer’s original
design, especially for critical items like the fuel system.
Drifting more into insurability than safety, Lauerman considers a three
legged stool of aircraft, pilot and operating environment, which includes
runway
length and the availability of crosswind runways. If one is marginal, the
other two had better be solid. Avemco provides discounts to customers who
have
taken the King Schools video on risk management, but Lauerman observes that
external pressures are seldom a factor in homebuilt accidents. Of more
significance is whether, when selecting the aircraft, the pilot understands
what
they have gotten themselves into.
……..
Added Notes:
(1) Lancair 320/360 at 1800 pounds is about 26 lbs per sq ft (70 sq ft wing
area). The Quad City's Challenger II that I built was 5.4#/sq-ft. The
Skymaster that I once owned was 22#/sq-ft.
(2) Underlining was added for emphasis.
Scott Krueger AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)
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