----- Original Message -----
From: Wayne G. O'Shea
To: rebel-builders@dcsol.com
Sent: Friday, February 23, 2007 2:11 AM
Subject: Re: [rebel-builders] Rebel - HEEEEeeeeeeeeeeeeeeelp ! (Airspeed Indicator) & now Tailwheel !
Rick..tailwheel should be 45 to 50 psi. I run mine 45 without issues.
----- Original Message -----
From: "Rick Harper" <rjwh@optusnet.com.au>
To: <rebel-builders@dcsol.com>
Sent: Thursday, February 22, 2007 3:23 AM
Subject: [rebel-builders] Rebel - HEEEEeeeeeeeeeeeeeeelp ! (Airspeed
Indicator) & now Tailwheel !
G'day Ken & Everyone !
Well - I took the plug out of the "low point drain" for the static line
(inside the cabin) , and went and flew LOTS today ... and ...
IT WORKED !!!
The ASI now reads within 1 knot at ALL speeds
(Bob was right too - when you open the cabin air inlet vents - the cabin
pressure goes UP & the airspeed readout drops ... but only by a half to 1
Knot - I can live with that !
At 4000' she stalls at 36 - 37 knots indicated (with 2 stages of flaperon
deployed) - but I suspect it would be more like 33 ish knots when you are
down on the deck in thicker air ...
The low speed controllability is GREAT ... but the ridiculous angle of
attack means that you can't see ahead ! - (almost defeats the purpose of
doing the whole cuffs & VG's thing :o(
I now find I land tailwheel first ALL THE TIME ...
Which means that as soon as the rear wheel touches - it pivots on it &
hammers the mains on - so much for the "slow & gentle touchdown" :o(
I now think this is a better setup for a tricycle U/C configuration !
But, there is lots more testing to come as yet - so we'll see ..
On a different note :
I am getting TERRIBLE tailwheel shimmy when landing on tar / concrete ...
Yes - I have the pivot bolt vertical ... (actually a tad forward at the
bottom - which everyone says is even better)
Yes - I have different strength springs on each side - from the rudder to
the wheel
AND - I have a 3 leaf, 2" wide STEEL spring assembly !
The only thing I can think of now is tyre pressure ... and maybe some sort
of friction system ....
WHAT tyre pressure do you guys all run in your taiwheels ???
(I was told today that Citabrias & Decathlons run 55 to 60 PSI ?!?!?!? ...
I have been running ours at 25 PSI !)
PS: I have a 10" dia SCOTT tailwheel - (off an Agtruck)
Other than that - ALL is going well
( Though I'd r....e....a....l....l....y..... like to get my hands on a
suitable WARNKE or PRINCE wooden "variable pitch propeller" ! ...
anyone got one they don't want ?!? - to suit 100 knots & a 180 ish HP
engine )
Biggus
541R ... FLYING !
----- Original Message -----
From: Ken
To: rebel-builders@dcsol.com
Sent: Thursday, February 22, 2007 3:39 AM
Subject: Re: [rebel-builders] Rebel - HEEEEeeeeeeeeeeeeeeelp ! (Airspeed
Indicator)
Hi Rick
FWIW I put the cuffs on before my first flight and changed my pitot to a
cessna probe with a small 1/8" orifice but it is 5" under the wing just
inboard and just barely ahead of the strut connection similar to what
Bob mentions. I haven't walked into it yet and it works fine at all
speeds. In theory the airflow is always parallel to the wing bottom in
that location. I also use cabin static but guess I need to find an
"exterior" source to get the static system signed off for transponder
legality.
Bob
You figure the cuffs cause you to cruise more nose down???
Hmmm - I thought the opposite and rationalized that the drooped
leading edge effectively reduced the wing's incidence.
Granted it does add more camber (makes for a more curved wing) but I
didn't think that mattered much at cruise speed...
Ken
still asking questions and learning :)
Bob Patterson wrote:
Hi Rick !
Congrats on getting flying again !! Great, isn't it ?!!!
Welcome to the Rebel ! The ASI problem you have is
NORMAL !!!! Almost ALL Rebel ASI's tend to read low on the high
end, and high on the low end ..... most likely because of the
huge range of angles achievable.
One solution is to go to a much larger diameter pitot tube -
say 3/8" +. This gives a wider area for pressure, and a better
chance of closer readings. Best location is about 3-6" below
the wing, about 1/3 of the way back - plain tube mounted on the
inboard side of the strut, fastened to the wing by thin, wrap-around
straps worked for me on 2 Rebels.... Most just use cabin air
for static - it's VERY difficult to find a good position for source.
You could play around with the angle of mounting the
pitot tube - likely it's different now than original. The cuffs
will likely allow cruise at a more nose-down attitude - but
unfortunately, also allow a ridiculously high attitude for
landing ! Test aircraft have the end of the tube mounted
on a pivotting shuttle-cock, so it's always aligned to the
airflow !
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