Static Port Location

Legeorgen · Post by **Legeorgen** » Fri Feb 17, 2012 10:28 pm

Hi Terry,

I have the same pitot/static tube from MAM. Mine has four holes drilled and 90 degree around the outer tube. I never did blow through it as Bob mentioned. I'll try that next time I'm out at the plane. You might try and blow through yours and see if it's clear. Let me know if it doesn't blow.

Bruce 367R

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Walter Klatt · Post by **Walter Klatt** » Fri Feb 17, 2012 10:28 pm

It seems there have been a lot of variations with MAM's
pitot tube. Mine came with a hole drilled in the side
for a static port, and is pretty accurate. I mounted it
on the left wing, with the static hole on the inside
pointing toward the fuselage.

However, another Rebel here locally, with the same
pitot tube has the problem with inaccurate readings. In
his case, though, the static port is on the bottom of
the tube. He tried putting the static port on the side
of the forward fuselage as suggested, but it was still
a problem there, too.

For some reason, mine seems to be OK, but have heard of
more installations that don't work than do. So, go
figure...

Walter

-----Original Message-----
From: murphy-rebel@dcsol.com
[mailto:murphy-rebel@dcsol.com]On Behalf Of
Bob Patterson
Sent: Wednesday, October 09, 2002 7:30 AM
To: murphy-rebel@dcsol.com
Subject: Re: Static Port Location

Hi Bruce !

This is a change, then. All of the tubes I've
seen here
didn't have ANY holes in the outer (static) tube -
that's why
they didn't work !!

Can you blow air freely through the static
line, out those
holes ??

In any case, that tube fastens to the leading
edge of the
wing - everything I've read says the best place for a
pitot is
about 4" below the wing, about 1/3 of the way back the
chord.

This makes the top stru fairing a pretty good
place to mount
a bracket to hold a 5/16" I.D. tube about 6" or 8"
long. The plastic
tube off the back can run under the fairing and down
the strut,
so it's easy to run up to the indicator. The large
diameter pitot tube
helps to compensate for the large range of angles that
the Rebel
flies at.

....bobp

Sorry to hear about SkyStar - they were a pretty
decent outfit.
Perhaps yet another "white knight" will appear to save
them !

-----------------------------------orig.---------------
------------
At 08:32 PM 10/8/02 EDT, you wrote:

Bob,

What do you mean "drill a hole in the side/bottonm of

the tube"? The tube

already has four static holes drilled in it. The

installation instructions

and MAM never mentioned drilling a new hole.

Bruce 357R
<HTML><FONT SIZE=2

FAMILY="SANSSERIF"
FACE="Arial" LANG="0">Bob,

What do you mean "drill a hole in the side/bottonm of

the tube"? The tube
already has four static holes drilled in it. The
installation instructions
and MAM never mentioned drilling a new hole.

Bruce 357R </HTML>

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Drew Dalgleish · Post by **Drew Dalgleish** » Fri Feb 17, 2012 10:28 pm

In any case, that tube fastens to the leading edge of the
wing - everything I've read says the best place for a pitot is
about 4" below the wing, about 1/3 of the way back the chord.

Hey Bob
You should see the test pitot tube on the new Found at Parry Sound. It's
about 2" in diameter and sticks out about 4' in front of the leading edge
of the wing. It's painted like a barbers pole :)
Drew
-----------------------------------------------------

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steenson · Post by **steenson** » Fri Feb 17, 2012 10:28 pm

Dear Bob,

Can't argue with you on these points. You make Canada sound like a
libertarian's paradise!

By the way, I'd certainly appreciate any further updates on your Nov. Rebel
builders' meeting, including speaker.

Best wishes,

Jeffrey

On 10/9/02 8:23 PM, BOB.PATTERSON@CANREM.COM wrote to MURPHY-REBEL:

->
-> Hi Jeffrey !
->
-> Not a problem for <me> !!! ;-) ;-^) :-)
->
-> I don't fly IFR, and I've always said that " a transponder
-> will be the LAST thing I ever buy !!! I refuse to spend my money
-> so THEY can tell where I am - and fine me if I screw up !!!! "
->
-> I'd MUCH rather spend my money on a good GPS, so 
-> can tell where I am !! ;-)
->
-> I've flown over quite a bit of North America, and it
-> <IS> still possible to go from coast to coast WITHOUT a transponder ....
-> or even a radio, although that's a bit more difficult now ! :-)
->
-> In fact, we're planning to do just that next summer, on
-> Rebel Ramble '03 - dip a toe in both oceans ! Everyone's invited
-> to fly along - we're going West in early July, for Arlington, then
-> East in late August, for Stanley, NS.
->
-> ....bobp
->
->
-> Sorry - just couldn't resist ! I know you folks who need
-> transponders have a real problem with static location - hope there
-> will be someone here who can help.
->

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Don Cormack · Post by **Don Cormack** » Fri Feb 17, 2012 10:28 pm

Don't blow through the pitot tube once it has been installed, you'll damage
your air speed meter!

Don

On Wed, 9 Oct 2002 20:16:03 EDT Legeorgen@aol.com wrote:

Hi Terry,

I have the same pitot/static tube from MAM. Mine has four holes drilled and
90 degree around the outer tube. I never did blow through it as Bob
mentioned. I'll try that next time I'm out at the plane. You might try and
blow through yours and see if it's clear. Let me know if it doesn't blow.

Bruce 367R

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

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Legeorgen · Post by **Legeorgen** » Fri Feb 17, 2012 10:28 pm

Hi Don,

I believe what Bob meant was to blow through the aluminum pitot tube itself, just to verify that it had been drilled out at the factory. You're correct though, if you blow through the tube while it's attached to your speed meter you will damage it.

Bruce 357R

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Terry Dazey · Post by **Terry Dazey** » Fri Feb 17, 2012 10:28 pm

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
Bruce:
No problem blowing through both the static hole and the pressure ports on mine (NO instruments were hooked up to it!). I guess that final install and flight will show if it works or not. I might hook a temporary optional static port up, so if the MAM's static port doesnt work correctly and I get irrenous readings, I can switch. First filght is not a good time to have bogus readings.
I have heard of one of MAM's pitot/static probes (airspeed indicator feedback) is off by quite a bit on a flying Rebel.
My ex-hangarmate Ron Wanttaja and writer extrodinaire (a book called "Kitplane Construction" and many articles over the years in KitPlane magaazine), had the same problem on his Fly Baby. He solved the innaccurate airspeed readings by affixing a washer over his 1/4 inch tube just in front of the static hole. Problem solved.
Have fun. Be safe.
Terry Dazey
Rebel 662

Hi Terry,
I'll try that next time I'm out at the plane. You might try and blow through yours and see if it's clear. Let me know if it doesn't blow.

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Legeorgen · Post by **Legeorgen** » Fri Feb 17, 2012 10:28 pm

Hi Terry,

Yea, I played around with the washer thing too but never got it to read right. An alternate source for static is a good idea, even if it's just being able reach under the dash and disconnect it and go with the "cabin" static air. Flying an unfamiliar plane, for the first time, without an accurate or even working speed indicator is not fun!

I will check my port tomorrow and see if it's open as well, but I'm guessing it is and just is not doing its job. Right now, with cabin static air, my indicated speed is 6-8 MPH high according to my GPS. I'll keep you informed.

Bruce 357R

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Mike's Email · Post by **Mike's Email** » Fri Feb 17, 2012 10:29 pm

An airplane in flight generally results in a slightly higher pressure inside the cabin than the ambient pressure outside. This will result in a slightly lower airspeed indication when using cabin air for the static source versus using the true ambient pressure of the air you are flying through. So your 6-8 mph high reading may actually be a bit lower than it would be if you were ideally using the ambient pressure. You may have another problem not related to your static source.

Mike Kimball
SR#044

----------
From: Legeorgen@aol.com
Reply To: murphy-rebel@dcsol.com
Sent: Friday, October 11, 2002 5:39 PM
To: murphy-rebel@dcsol.com
Subject: Re: Static Port Location

<<File: ATT00000.htm>>
Hi Terry,

Yea, I played around with the washer thing too but never got it to read
right. An alternate source for static is a good idea, even if it's just being
able reach under the dash and disconnect it and go with the "cabin" static
air. Flying an unfamiliar plane, for the first time, without an accurate or
even working speed indicator is not fun!

I will check my port tomorrow and see if it's open as well, but I'm guessing
it is and just is not doing its job. Right now, with cabin static air, my
indicated speed is 6-8 MPH high according to my GPS. I'll keep you informed.

Bruce 357R

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Legeorgen · Post by **Legeorgen** » Fri Feb 17, 2012 10:29 pm

Mike,

I thought that too but didn't have enough confidence to be sure that I wasn't thinking in reverse. That would mean my ASI is even more in error. Could a new air speed indicator be that far off? Say 10 MPH. How much difference would cabin/ambient air make all else equal?

Bruce 357R

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