Stall Speed Response

[Gary Gustafson]

I will reply to the following helpful emails with 3 answers

1. Walt - That is a very good reduction in stall speed which leads me to two
other questions.

First what is your indicated stall speed with VG's now at 18 degree
flaps. Second, How

did the VG's affect your top speed? I am sure others would like to know
these figures.

2. Drew - Yes I calibrated against a GPS and the static ports (have two -
one on each side)

is on the tail cone 1/3 of the way back from the cabin. I believe that
should be okay. My

pitot hangs down 6 inches just outside of the strut which also should be
okay. However,

I did talk to GRT (the manufacturer of my EFIS) and find that I may have
calibrated the

airspeed table wrong. I recorded stalls and airspeeds while in the air
and then entered the

data into a table in the GRT EFIS. It turns out that I should have had
the GPS in the GRT

EFIS average in the wind and with the wind speeds and have it populate
the table while

flying so that it can adjust for pressure altitude. Also the stall
points should be calibrated

from the corrected airspeed data already contained in the unit. GRT
tells me that I could

have compounded errors by not doing the calibrations in the air. So I
thank you for

questioning my airspeed and causing me to reread the instructions more
carefully.

3. Hank - I have been impressed with what I have read about LRI's and am
tempted to get

one. However, my GRT EFIS also has an AOA indicator that is supposed to
not be

affected by weight and weight distribution. I was getting disappointed
in the new feature

added as id did not seem to work right (which I now think is my error -
one of many). So

I will hold off until I recalibrate my GRT EFIS and see how it works (It
is supposed to be

within 1 degree if calibrated right). However, I would like to see your
pictures of your

installed LRI if it is not too much trouble. Send to email off-line.
Thanks



I also appreciate all responses to my questions as it is a learning
experience for me and I

hope others.



Gary Gustafson



----------------------------------------------

1. From Walter Klatt
My VG's lowered the stall by about 8 or 9 mph, according to my ASI, not

verified by GPS.



-----------------------------------------------

2. From Drew Dalgleish
Seems high Gary. Have you checked your airspeed against a GPS? Is it

possible that your static port is in a low pressure area? My airspeed

indicator always reads higher than my GPS unless I have a screaming

tailwind. I'm using the MAM pitot/static tube and it doesn't leak.



----------------------------------------------------------

3. From Hank Balch
I have a LRI on my Rebel and love it. On takeoff I watch the LRI and when

the needle moves into the yellow I know I have the speed for takeoff and

rotate. I also use it on landing. This is a real valuable instrument and I

rely on it more than my airspeed indicator during critical phases of

flight. I can send you some pictures of my installation if you are

interested.







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