REFLECTOR:Stall Characteristics

Wed, 12 Nov 2003 10:08:07 -0700

Scott,

I did not realize you were a CFI and also was unaware of how many hours in 
a Velocity you have. I am revising "my opinion" of "your opinion"! :-)

This conversation has gotten away from us.

It started with a statement that you could deep stall the airplane if you 
flew it outside of "Normal Flight".  The problem being how to define normal 
flight.

Are rolls normal?  If not the statement is false, I'm no aerobatic expert, 
far from it, I get airsick, however I've done quite a few rolls in canard 
airplanes.  I've flown very steep turns which I believe in excess of 60 
degrees is considered aerobatic.  I've been upside down, I've been throne 
around pretty good in turbulence, had some moments with clear air mountain 
wave/roll cloud type turbulence that put the airplane in attitudes I had 
never experienced before.  Is that all normal flight?

I never felt anything remotely like a deep stall though I've seen my 
airspeed down as low as 45 knots, in flight, well lets say I was airborne, 
certainly not flying in the normal manner...

I have no intention of deliberately performing a hammerhead stall. But 
similar wind can be induced in turbulence.

Saying all that, I think you are wrong in proposing that if you did manage 
to stall both wings through a maneuver like a hammerhead or some very rough 
turbulence that the nose would not drop out below the main wing.

Scott

At 06:12 PM 11/11/2003, you wrote:
>Scott,
>All I'm saying is that:
>1) The aircraft is not designed to perform aerobatic flight and especially
>slow speed aerobatic flight such as hammerhead stalls
>2) I wasn't born yesterday, and while I don't at all pretend to be an expert
>at aerodynamics - as a CFI with close to 1,000 hours of flight experience in
>Velocity aircraft - I am would be quite worried about inviting a deep stall.
>Opinions do matter.  What makes you take one CFI's opinion as gospel and
>discount another's as garbage?
>3) The purpose of my message was to get people thinking about the
>consequences of a deep stall and to act responsibly.  I really don't know
>how the aircraft will behave following a hammerhead type maneuver.  If
>someone has been there - done that, I would love to hear about their
>experiences.  I don't think that anyone has - I know the current flight crew
>at Velocity have not - and so the subject is open to speculation.
>4) Unless you have personal experience - or know of someone who has personal
>experience who can testify as to the aircraft's behavior following a deep
>stall - I think it is dangerous to offer an opinion that the aircraft is
>(deep) stall proof.  I think the aircraft can be deep stalled - I think the
>aircraft can recover from a deep stall - but I think it will take several
>thousand feet of altitude and an engine/propeller combination that offers
>thrust to help the aircraft out of the stall.
>5) If we were to judge which opinion should prevail - caution vs.. "go
>ahead, nothing bad can happen" ... guess which opinion I'm going to listen
>to.
>I don't understand why you are so defensive regarding an issue that if you
>were wrong, could cost someone serious injury or death.
>SB
>
>----- Original Message -----
>From: "Scott" <scott@tnstaafl.net>
>To: <reflector@tvbf.org>
>Sent: Tuesday, November 11, 2003 6:58 PM
>Subject: Re: REFLECTOR:Stall Characteristics
>
>
> > At 11:19 AM 11/11/2003, you wrote:
> > >I think that those who are debating the stall characteristics of the
> > >Velocity are making associations to the aircraft's behavior when it is
>put
> > >into a normal "pitch-buck" kind of stall.  Yes, the front wing looses
>lift.
> > >Yes, the nose drops when the canard stalls - but does the nose fall
> > >(primarily) because of the CG of the aircraft - or is the nose drop
>"helped"
> > >by the fact that the main wings are continuing to develop lift?
> >
> > Scott,
> >
> > It would be prudent to get ahold of somebody who knows the aerodynamics of
> > a canard to speak about this matter.  You have or had 3 CFI's that work
>and
> > fly these things every day.   I have talked to two of your paid  A&P/CFI
> > types and they told me in no uncertain terms you cannot deep stall the
> > Velocity if it is within gross weight and CG.  Now maybe they were
> > referring to everyday kind of flying, I don't think so.  I was pretty
>clear
> > about my question.
> >
> > >What do you suppose might happen if a Velocity were lifted by a balloon
>and
> > >then released?  With no airflow over any of the control surfaces the
>pilot
> > >can "pump" the controls like mad ...and even with the propeller running,
> > >nothing would happen until sufficient air flow is traveling over the
>control
> > >surfaces.
> >
> > PURELY HYPOTHETICAL , that's what that is.   Scott you are associating the
> > aft cg deep stall flying characteristics and making the leap that that
> > scenario apply's to a properly weighted aircraft.  With no basis in
> > engineering analysis or practical experience.
> >
> > >We all know how light the nose weight is in our aircraft.
> >
> > Oh yeah, have somebody sit in the front seat and try to lift the
> > thing!  Ever done that?  Its plenty heavy.
> >
> > >   If the
> > >aircraft were dropped in a level attitude, would the gravitational weight
>of
> > >the nose overcome the upward force of the air on the canard - in other
> > >words, without forward motion over the elevators, and without the main
>wings
> > >lifting the rear end of the aircraft, is the nose going to drop ... or
>will
> > >the forces of the air under the canard keep the nose from dropping while
>the
> > >aircraft is falling?
> >
> > You don't know do you?
> >
> > >I've never tried to initiate a deep stall (I don't think I'll ever have
>the
> > >tempted)!  Recovery (in my opinion) is linked to forward air speed.
> >
> > Ah, we finally get to the meat of your argument,  this is "your
> > opinion"....  Well we all got those....
> >
> > Scott
> >
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