There is no
such thing as stallproof. An updraft can stall a wing. There are some very
successful designs that have reduced the probability of the inattentive
driver getting into one. The cunards and aerocoupe are two examples. The
short cord thick section airfoil no the front of the cunard is supposed to
stall before the big wing in the back. A builder of a 4 place cunard in
Florida was flying in circles above his home trying to get his wifes
attention. He was inattentive, and in a tight steep turn, he stalled the big
wing in the back. The plane rolled to wings level with the nose high and
started down in a slow flat spin. The elderly driver was wishing that his
wife would not come out of the house and see him crash his new plane in front
of her. No control input had any effect. Changing the power had no effect. He
shut off the engine. The plane fell into the canal behind his house. He
climbed out and walked into the house.
He called the kit manufacturer (also in Florida) and told his story.
The designer went out the
next day in the prototype with full insturmentation and a chase plane, and
attempted to reproduce the accident. At altitude above the atlantic he tried
everyting he could to get the thing to stall. While bobing the nose up and
down in a tight turn and dragging first one rudder then the other, all of a
sudden.......the nose stayed up, the wings rolled level and down she went in
a slow flat spin. He tried everything and then some. He decided to get out,
and shut down the engine and opened the door. He looked at the VSI...He
looked at the altimeter. He called the chase plane. How fast am I
falling?...The VSI is hardly moving. Same here says the chase plane. So he
closes the door and belts up. The aircraft hits the Atlantic a few hundred
feet from shore with no injuries. A gang of kids help drag it up on the
beach. Today that kit has leading edge cuffs in front of the ailerons, and it
is moore stall RESISTANT. Lynn E. Hanover
Stick force per G is the usual term. Stick angle per degree of pitch
does not mean much because there is little choice in the angle of
the elevator to the angle of the stick for manual controls because people's
arms are only so long. It has to do with the technical definition of
"work" (force times a distance) but that is a whole other book.
As I recall some guy spun in inverted from relatively high altitude, in a canard,
after being up set by wake turbulence. He was talking to the controller on the
way down while moving around the cockpit trying to change the CG.
He was not so lucky.
Paul Lamar
Charlie and Tupper England wrote:
Isn't it important to note that in both the Velocity cases (Lynn's
examples) the planes were being flown with the cg aft of recommended
limits? The first was by 'accident' & the second on purpose during testing.
Also, every 'deep stall' in EZ's I've read about was attributed to
either cg aft of limits or unauthorized changes to the winglets. A
Cherokee or Cessna can do the same thing with cg aft of limits; you just
won't get the advantage of a 100 fpm sink rate like the Velocity.
The Velocity incidents point to why I'm always glad to see efforts being
made either 'outside the box' or to reshape 'the box.'
Consider this: if the Velocity incidents can happen twice (actually it's
happened more times, I think), we could learn through some time & effort
how to control this behavior. Consider the safety value of a plane that
is its own ballistic recovery chute, in the event of power loss with no
safe landing zone.
Just because a BWB hasn't worked in the past doesn't mean that it won't
work in the future. The fuel injection on my old '72 Alpha Romeo rarely
worked, but I won't leave home without fuel injection on my current
cars. And, I'm happy to have the computer controlling it.
As long as I don't have to pay for the product before it's available,
I'm happy to see anyone take a stab at any new idea or variation on an
old one.
Charlie
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