BRS and descent rate

"Paul Tomblin" wrote in message
...
In a previous article, "Roger Long"
om said:
"JJS" jschneider@REMOVE SOCKSpldi.net wrote in message
...
I had a flying buddy do something similar last fall in a Velocity.
Sort of a falling leaf maneuver that he inadvertently entered and
A Velocity is a Canard, isn't it? They have some weird issues with
mushing. Leaving my plane trimmed for the bottom of the green arc, I was

Yeah, they get into something called "deep stall". I don't know the
aerodynamics exactly - something about the wing and the canard being
stalled at the same time or something, but I do remember a test pilot (and
Shuttle astronaut) getting killed testing this phenomena on a canard.

Actually, the Velocity will not get into a "deep stall." There was one
example that did do this a few years ago -- twice! Both times the plane
landed in water and was salvaged. The pilot was unhurt both times. The
second time was deliberate. The test pilot even tried to climb out onto the
nose to break the stall. Although he was wearing a parachute, he elected to
ride the airplane down as it was descending more slowly than a parachute
would. A Velocity rep told me that this plane had been modified from the
original design. Mounting the airplane on a flatbed truck with a hydraulic
lift to raise the nose identified a problem with the trailing edge of the
wing. There was a lot of discussion about it in Velocity groups, but the
"deep stall" problem was peculiar to just this one airplane.

Canard aircraft are designed to have the canard stall before the main wing,
forcing the nose to drop and break the stall. Consequently you can never
achieve maximum lift from the main wing because the canard will always stall
before the wing can reach its maximum angle of attack. Canard aircraft
therefore need longer runways and often need more runway to land than they
need to take off. Soft field capability is also limited by the canard
design. OTOH canard aircraft have less drag in level flight since both the
canard and the wing generate upward lift. They tend to be much more fuel
efficient than their tail-feathered counterparts.

There are a few canard aircraft that do have a problem with deep stalls.
IIRC the Dragonfly is one. And of course the original Wright Flyer was not
only a canard design, but also was a pusher type with counter-rotating props
and a variable geometry wing -- just like the "advanced" designs that NASA
is looking at today.