The Murphy Builders Site

Does anyone know the distance between the root rib and the fuselage? I'm
trying to figure out whether to use an angled bulkhead fitting for my pitot
tube installation, or to just use a straight one. I think straight would be
better to prevent a sharp turn inside the fuselage to wing fairing, assuming
I can come straight across from the wing to the fuselage with my nylon
tubing, then into the cabin. Is it OK to use 90 degree nylon fittings here
and there for the pitot tube?

Mike Kimball




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In a message dated 3/4/01 12:48:58 PM Central Standard Time,
agt@mosquitonet.com writes:

Does anyone know the distance between the root rib and the fuselage?

MIKE
It's aprox. 2 3/4" but you only have about 2" to get you're hand in there
because of the lip on the wing made to mount the root fairing.
Phil&Lisa Smith #460 N414D

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Since most of the email traffic on the list is for Rebels, I'm guessing that these distances are for a Rebel. May be a bit farther for a Super Rebel, which I am building, but either way I think it would be better for me to use a 90 degree angle fitting. It will be easier to get at it from below that way too. Since air doesn't actually move continuously in the pitot tube, I'm guessing that the tube will be relatively uniformly pressurized all the way to the airspeed indicator, with some drop in pressure over distance, through the turns and twists, and through the filter, but not enough to make much difference. If I am concerned about a knot or two of inaccuracy, I suppose I could get out my old Aerodynamics for Naval Aviators book and try to compute a calibrated airspeed compensation for system installation errors. Right after I compute the propagation of load distribution from the wing root to the tip, and the calibration of the quartz fizzlenorker tube. In other words, I think I worry too much.

Mike

-----Original Message-----
From: murphy-rebel@dcsol.com [mailto:murphy-rebel@dcsol.com]On Behalf Of LisaFly99@aol.com
Sent: Sunday, March 04, 2001 10:17 AM
To: murphy-rebel@dcsol.com
Subject: Re: Wing to Fuse Distance


In a message dated 3/4/01 12:48:58 PM Central Standard Time,
agt@mosquitonet.com writes:

Does anyone know the distance between the root rib and the fuselage?

MIKE
It's aprox. 2 3/4" but you only have about 2" to get you're hand in there
because of the lip on the wing made to mount the root fairing.
Phil&Lisa Smith #460 N414D

Mike, I've got a great spread sheet that will
calculate the eddie current variances for
fizzlenorker tube calibartion.

Let me know if you want a copy.

Mike D

Right after I compute the propagation of load

distribution from the

wing root to the tip, and the calibration of

the quartz fizzlenorker tube.

In other words, I think I worry too much.

Mike

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On 5 Mar 2001, at 10:06, AGT wrote:

would be better for me to use a 90 degree angle fitting. It will be
easier to get at it from below that way too. Since air doesn't

airspeed indicator, with some drop in pressure over distance, through
the turns and twists, and through the filter, but not enough to make
much difference. If I am concerned about a knot or two of inaccuracy,

Pressure loss is a friction effect, so it depends on flow volume per
area. You'll get a slowdown of response with greater restriction, but
once you're at some constant airspeed or altitude, there's no flow
and therefore no pressure drop. Pitot and static source placement
are the real source of instrument errors.

---
David Parrish




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In a message dated 3/6/01 1:31:24 AM Central Standard Time,
agt@mosquitonet.com writes:

but either way I think it would be better for me to use a 90 degree angle
fitting. It will be easier to get at it from below that way too.

MIKE
I used nylon tubing for my pitot static lines. Ran them straight no 90deg.
There was plenty of room for them to make a bend without stress or kinking.
On the out side of the fuselage I put a splice type compression fitting to be
able to undo the line for wing removal. This was on a Rebel and I have just
enough room. On an SR I'm sure there's more room. I'll try to send a couple
of pictures to show the inside with the nylon tubing.
Phil&Lisa Smith #469 N414D

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Calibartion must be a variation of the calibration I used. Probably that
new math their teaching nowadays.

Mike Kimball

-----Original Message-----
From: murphy-rebel@dcsol.com [mailto:murphy-rebel@dcsol.com]On Behalf Of
mike.davis@dcsol.com
Sent: Monday, March 05, 2001 10:37 PM
To: murphy-rebel@dcsol.com
Subject: RE: Wing to Fuse Distance


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Mike, I've got a great spread sheet that will
calculate the eddie current variances for
fizzlenorker tube calibartion.

Let me know if you want a copy.

Mike D

Right after I compute the propagation of load

distribution from the

wing root to the tip, and the calibration of

the quartz fizzlenorker tube.

In other words, I think I worry too much.

Mike

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Nope, just fingers going faster than the brain!

----- Original Message -----
From: "AGT" <agt@mosquitonet.com>
To: <murphy-rebel@dcsol.com>
Sent: Tuesday, March 06, 2001 9:59 AM
Subject: RE: Wing to Fuse Distance

Calibartion must be a variation of the calibration I used. Probably that
new math their teaching nowadays.

Mike Kimball
----------------------------
Mike, I've got a great spread sheet that will
calculate the eddie current variances for
fizzlenorker tube calibartion.

Let me know if you want a copy.

Mike D
-----------------------------

Right after I compute the propagation of load

distribution from the

wing root to the tip, and the calibration of

the quartz fizzlenorker tube.

In other words, I think I worry too much.

Mike

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