REFLECTOR: 65VT/ angle-of-attack system

Brian Michalk michalk at awpi.com
Wed Oct 6 19:46:39 CDT 2004


Today was "Wednesday Airplane Guy Lunch Day."

We were talking about AOA and the canard.  In your message,
http://www.tvbf.org/mailman/private/reflector/2004-October/007031.html
you talked about AOA, and there's something I wanted to get clear.

>From my understanding an airfoil will stall at a specific angle of attack.
Is this true?

If yes, then it would seem to follow that the canard/elevator combination
will also stall at a specific AOA depending on the amount of elevator
deflection (chord).
For instance, elevator deflected 10 degrees, stall AOA is X1.  Elevator
deflected 20 degrees, stall AOA is X2, and so forth for any deflection angle
you will have a specific Xn.

Next question; this was an argument we had.  I felt that stall AOA is
independent of air density.  Is this correct?  Will an airfoil in water
exhibit the same stall AOA as an airfoil in air?

One last question.  Not all of our canards are the same.  The ones built by
Alan shaw apparently have more camber.  Are we using a standard NACA
airfoil?  Which one?  Is there any data available?  I know you probably
don't have this information.  Maybe Scott Baker would know?

Also, assuming one wanted to do some testing on a full sized airfoil, but
one that is shorter than the standard canard, how long should it be?  I was
thinking a two foot section of canard would be plenty if pressure sensors
were fixed in the middle of the airfoil.  The test would determine the
pressure distribution at different angles and different elevator
deflections.

 Brian Michalk  <http://www.michalk.com>
Life is what you make of it ... never wish you had done something.
Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
musician, home-brewer, entrepreneur and barely single


> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Jim Sower
> Sent: Tuesday, October 05, 2004 11:07 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: 65VT/ angle-of-attack system
>
>
> <... Are you saying you normally land at 70? How much weight is in the
> front seats? What wing/airframe configuration? ...>
> Standard 173 converted to gull wing doors from top loader.  280 - 460#
> in front seat (depending if wife is along).  70 kts if the air is
> smooth.  75 if it's choppy and still 80 if it's really rough or >10 kts
> x-wind.  Actually, on choppy days, if things smooth out and I'm
> comfortable crossing the fence, I cut early so as to do most of my
> "floating" in the overrun.  I HATE to land long.  I virtually never
> touch down as far down the runway as the "IFR stripes".  Nearly always
> within 5-10 yds of the numbers, VERY rarely short of the numbers.
>
> Probably a good practice; probably a bad habit .... Jim S.
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