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<< Lancair Builders' Mail List >>
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>We put the LNC2 through its paces and came up with a dirty configuration
circle to land stabalized approach descending at 500fpm at 70KTIS. It
stalls at 63KTIS<
I realize that the above was information for dire emergencies
however, we should make it clear that this is NOT an adequate
margin above stall in a Lancair during approach under any
circumstance and especially in the mountains.
The stalling speed of an aircraft varies depending
upon gross weight, bank angle, and CG
and other factors. The IAS meter has errors that are
worse the slower you go and you can stall an aircraft
at any IAS up to its maneuvering speed.
Let's assume the IAS was right on and the approach was
shot and maintained at 70 knots and the stalling speed for
that approach was infact 63knots as indicated above.
A minor 1.25 "G" bump from a thermal or ridge lift during
approach WOULD HAVE STALLED this aircraft without
enough altitude to recover.
I'm especially concerned that the above approach
was a circling approach. A typical 20 degree bank
would have reduced the stalling margin to only a few knots.
In addition, this aircraft was operating well on the back
side of the speed stability curve without enough
energy to stop the descent which is especially
dangerous if the engine quit or if this emergency
approach was shot with a failed engine.
I give forums on AOA flying at Sun'n Fun and Oshkosh
every year. Because I'm an old mountain instructor and bush
pilot, we discuss some of the above issues. I invite you
to attend. Last year the Oshkosh forum counted towards
the instructor's refresher.
Tip ----- Always contact the ground at shallow
angles.
Jim Frantz
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Please send your photos and drawings to marvkaye@olsusa.com.
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