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Colyn,
I installed my sensing
switch (per Jim Frantz) so it activates the “Flaps” annunciation,
and goes to the “flaps down” AOA configuration as soon as the flaps
start moving from the full up position.
These functions are both controlled by the flap sensing switch and can’t
be triggered independently as far as I know.
I believe that at a given
weight and airspeed, the wing generates more lift but the same angle of attack
indication on the AOA (pressure differential between upper and lower wing sensing
ports) with the flaps down. If you calibrate the AOA system to “flaps
down” stall speed, it will be at a lower indicated airspeed than when the
flaps are up.
This means that when the
AOA system goes into “flaps down” indicating mode, it will be
showing “on speed” and “stall” at a lower indicated airspeed
than that at which the airplane will actually stall with partial flaps. It
would indicate the correct stall AOA only at the position it was calibrated
(flaps full down).
I therefore think the most
conservative installation would be to switch the system to “flaps down
mode” when the flaps are fully down. As a practical matter, if I were doing
mine again, I’d set the switch to change when the flaps go past 20
degrees…or more specifically, when they change from moving aft to rotating
down.
There is another way to
do this. You can calibrate the AOA at any airspeed (within reason) and
configuration (flaps up, flaps partial, or flaps down) you chose. The machine
simply displays AOA measurements that you’ve previously told it were
stall AOA’s in various configurations, so you can make it repeat these
back to you at the speed/configuration you chose. I am not advocating creative
installation/calibration here, just understanding what you are actually
calibrating this very good system to show…
My two cents…
Bob
Posted
for Colyn Case <colyncase@earthlink.net>:
while we're on this, I'm interested where others, especially IVP owners,
put
their flap switch for the AOA, and what the AOA really does with that
information. Roughly speaking, it's going to store separate
pressure curves
for flaps on and flaps off. but which would be most conservative:
a) put the switch so that it detects ANY flaps
b) 10 degrees
c) 20 degrees
d) full
My thought was to put it at 12 degrees or so.
Colyn
[Having worked many airshows with Jim Frantz, the developer of the AOA Pro, the
standard answer to your question was to install the flap switch so it actuates
with any flap actuation. It simplifies the installation and is the most
conservative setting. FWIW.... <Marv> ]
On Oct 3, 2010, at 7:46 PM, Bill Bradburry wrote:
> John,
> There is a microswitch on the flap torque shaft that tells the AOA Pro
that
> you have lowered flaps. It dutifully tells you that it knows
that by
> announcing "Flaps!". It that is happening over and
over, you have a loose
> connection or short or bad switch.
>
> It is located somewhere under the seats.
>
> Let us know what you find.
>
> Bill B
>
> -----Original Message-----
> From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
John
> Hafen
> Sent: Saturday, October 02, 2010 1:05 PM
> To: lml@lancaironline.net
> Subject: [LML] "FLAPS" Warning Voice
>
> Gents,
>
> I have a IVP with duel Cheltons and an AOA Pro. Taxiing out,
after lowering
> my flaps to 10 degrees for takeoff, I get a random "FLAPS" voice
warning in
> the headset.
>
> After takeoff and raising the flaps, the voice mercifully goes away.
>
> Back in the pattern, with the flaps down, the voice warning starts up
again.
> It squawks if I have one, two, or three notches of flaps down.
>
> On roll-out, after the flaps are retracted, the warnings cease.
>
> Question for the group: How do I make the voice warning go
away?
>
> My AOA is calibrated, and I've been all through the Chelton setup screens
to
> no avail.
>
> Please let me know what I'm missing.
>
> Thanks in advance.
>
> John Hafen
> IVP 413AJ
> 275 hours
>
>
>
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