I am wondering if one has a Europa with a tendency to drop a wing, if it
could not be severely helped by simply adding a bit of NASA Lead Edge
droop???
Reading on the books written by Don Dykens, he calls it another name, but
essential states that on the Europa super efficient wing he incorporated
the perfect amount of NASA lead edge droop to give good slow speed
performance with minimal top speed drag.
To digress a bit, on my 4 foot span model, that I normal fly between 19
and 46 oz AUW, since there were many nay Sayers that AUW should be kept
below half of my 46 oz, I figured I should find out just how heavy could
go before something happened.
Kept adding weight till I was at 72 oz and it flew pretty good, just fast.
This was bungi launched so flight times were limited. So we built a real
sample with 16 cells and 3/4 of a HP. Absolute stink fast, pure vertical,
but landings were a bear, even though it had 3 degrees of washout, the
thing was so heavy, when you got slow and tried lifting a wing, the
aileron would stall the wing, upside down into the ground right now!
Not taking no for an answer I began to investigate NASA Lead edge droop.
this is a flying wing so anything you do on the trail edge also effects
pitch. I began adding some NASA Lead edge droop as Don depicts that some
older English airplanes used to do, just whittle some wood, get it stuck
and go fly and try!
It worked where the plane turned from a 1 out of 3 landings guaranteed
crash, to a pussy cat. Top speed suffered a little. The plane WAGMAX was a
great success, that is until the spar system failed. Instead of a rebuild,
we created WAGMAX 2. What do you do to a beast like this? Made a plenty
beefy spar, got a thinner wing, less wing area and increased weight to 80
oz AUW!
The difference is we installed in flight articulatable NASA Lead Edge
droop. Take off with 20 degrees, when going fast go to zero, and get this,
we made it so when going super fast, could go to negative droop! Ends up
that the negative droop seems to negate the 3 degrees washout and boy does
it go fast, just do not stall it as spin would occur in an instant and be
absolute unrecoverable.
Ends up I got an E-Mail from the guy who was on the team at NASA
investigating NASA Lead edge droop, and he was absolute encouraged at
where we had taken that technology, to use it on a flying wing for drag,
and anti spin. He said that they ran out of money and only investigated a
small amount of potential usefulness.
Boy am I long winded.
Anyway the point is I think a Europa with bad stall habits could very well
be enhanced without too much performance loss. For one thing the stall
speed would not be increased. I don't think it would be very dangerous to
test a little at a time, just may be that it may eat a little too much
into performance.
I would rather have an airplane that was 5 knots slower in cruise but had
fair benign stalls at a slow speed, rather than have a plane that cruised
5 knots faster, had a 5 knot faster than slow speed stall, and was not
benign.
Anyone have ability to run this idea past Don Dykins, Ivan Shaw or??
Ron Parigoris
My partner Wayne modeled a XS Monowheel for X-Plane. Could fool with that
to get idea how it would effect stall??
BTW in X-Plane you can turn on force lines and see the dynamics happening.
You can not believe at just how much down force begins to occur on the
wing outboard of the flaps if you fly much past max. flap speed. Foolish
me, I always thought going too fast with flaps down may tear off flaps.
Looking at dynamics that occur, twisting of the wing and failing it quick
come to mind.
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