Static "port"

[mulwyk]

There's been some criticism of the static-in-wing method. That's exactly what I found in my project plane. The static line was just laying in the bottom of the left wing next to the second rib.

What sort of static hook up do others have? Why not simply leave the static open behind the instrument panel?

[Hank Jarrett]

Re: Static "port"

Mine simply didn't have a line from the back of the instrument for static. Of course opening or closing the window could show some SPECTACULAR performance!

The problem is you need to actually make some tests to find a place on the plane where static is really "STATIC". Lots of planes actually have two or more ports tied together to balance out attitude effects.

The second problem is once you find the perfect place to take static, the Feds may want to "approve" it.

Funny how they can stop you from doing something that causes NO HARM and provides a nice improvement because it doesn't fit with their rules.

All that said, I would like to hear where others have their static port.
Hank

And how it works out!

[cvavon]

Re: Static "port"

The static side of instruments on 26658 is a short rubber hose with what looks like a small paper filter in the end of the hose seems to work fine all instruments are very accurate Chuck

[Pearson]

Re: Static "port"

Mine has about a foot of vacuum line that ends behind the instrument panel.

[flyguy]

Re: Static "port"

The one in the wing on my 12D is accurate for the airspeed at very low speeds near stall where it is dead on.

As the airspeed goes up the error does also. Indicated is about 8 MPH high at flat out. Checks out the same with 3 different ASI's including the new one installed now, so I am pretty sure the problem is the change in pressure in the wing with changes in airspeed.

Kinda makes sense as the biggest hole in the wing is on the trailing edge at the aileron control exit.

Conversly the ROC indicator is open to the cabin and will fluctuate if I change the window opening.

Had I my choice, and the wing open for access, I would be tempted to install the dual tube pitot sensor with the pinhole static port on the second tube.

The one on a friends Aeronca K has a tiny disk slid over the static tube in front of the pin hole that I suspect is to produce turbulent/dead pressure area at the pinhole.

Looks like a good setup to me.

DC

[cvavon]

Re: Static "port"

I have a static port i bought at spruce is Cessna type P/N 0-00250 it is for wood, metal, fabric drill 19/64" hole use 1/4" ID tubing/hose push it on all the way and hose will hold the port on side of air plane Chuck

[barnstmr]

Re: Static "port"

What we are talking about is "calibrated" airspeed. Error due to static port placement should be corrected out if you want to be able to determine calibrated airspeed. It is difficult to develop a correction card to address that error without flight testing and comparing your gauge to a known "standard" accurate gauge. In the flight test world this is done using a special boom (you've probably seen them) that places the pitot and static ports out in un-disturbed air. The variations seen on old airplanes due to static probe placement is generally accepted.

One poor-mans way to get a good idea of your gauge accuracy is to use a GPS and fly reciprocal headings (90 degrees to prevailing wind) for a period of time at a specified indicated airspeed, then average the two GPS numbers and use this as your known "standard". Repeat this for various airspeeds and log all of your data. Now you can plot a curve on a graph with indicated airspeed vs. GPS airspeed. Now you can connect all the dots and use it to correct for error at any airspeed between the dots. There have been some good articles written in sport aviation and other places about this. Give it a try.

If nothing else... this would be a fun way to bore holes in the sky and have more fun in your Tcraft.

[mikeg]

Re: Static "port"

The static plumbing in my '41 DeLuxe runs up the left front door post and terminates above the headliner. A '45 I did had the static run up the left front door post and out into the left wing to the second compression tube out and was then taped to it. I have reason to believe that both were original. Forrest my have some input.
Mikeg
NC29804
NC27451

[flyguy]

Re: Static "port"

I am pretty sure all 3 of my 12D's have the static port in what I think of as the stock location in the left wing.

The GPS method mentioned above is exactly how I know that my stall speed indication is dead on and the top speed is high. I didn't specify that because I have talked about it here before, and I have come to think that, with the GPS so common nowadays, everyone would have figured it out long ago.

It would be nice if mine would go as fast as it indicates, Chuckle.

Darryl

[NY86]

Re: Static "port"

fly reciprocal headings (90 degrees to prevailing wind) for a period of time at a specified indicated airspeed, then average the two GPS numbers.

Not sure, but I don't think this will work. Your head/tailwind components will cancel out but your drift will be the same direction both ways. I think it will work if you fly one leg into and one away from the prevailing wind (no drift). Also, there is a calculator on the web that takes 3 legs at 90 degrees to each other and computes TAS from that, here.

[VictorBravo]

Re: Static "port"

I did some tests on a Taylorcraft using a glider pitot-static probe. This is a coaxial pitot and static sensing device. They are very finely calibrated.

You can get them at Wings and Wheels in upstate New York, I think it's wingsandwheels.com. The proprietor it Tim Mara, a good guy. They stock all sorts of them. If you are willing to make a slight modification to your airplane, you can install one of these gizmos and have a guaranteed good pitot and static source. This should go without saying, but please mount it well outside of the prop arc Sticking out forward of the wingtip would be the best place on the T-craft.

If you're interested, call the guy and tell him you need a two-function pitot-static tube for a powerplane, NOT a "total energy" or TE glider probe.

Here is the page: http://www.wingsandwheels.com/page19.htm

and scroll down to the bottom of the page. Remember, a powered airplane does not need the TE (total energy) function, we just need a good pitot and static probe like the Prandtl tube at the bottom of the page.

[TimHicks]

Re: Static "port"

I'm kind of embarassed to admit it, but when I bought my airplane 17 years ago, I saw the static line in the wing and figured something was wrong. So I made the static port shown and temporarily zip-tied it to the Jury strut to test it out. 17 years later, it's still zip-tied to the jury strut (even after the jury strut was repainted during the main strut replacement a year or so ago).

I also attached my entry to the calendar photos. My family and coworkers can't understand what I like about the prop hub picture, so I wanted to bounce it off of y'all to see if I get any appreciation.

[Howard Wilson]

Re: Static "port"

Beauty is it's own excuse for being. R.W. Emerson

[Pearson]

Re: Static "port"

Tim,

Have you checked your speeds to see how close they are with your static port setup?

[Larry Lyons]

Re: Static "port"

I'm kind of embarassed to admit it, but when I bought my airplane 17 years ago, I saw the static line in the wing and figured something was wrong. So I made the static port shown and temporarily zip-tied it to the Jury strut to test it out. 17 years later, it's still zip-tied to the jury strut (even after the jury strut was repainted during the main strut replacement a year or so ago).

I also attached my entry to the calendar photos. My family and coworkers can't understand what I like about the prop hub picture, so I wanted to bounce it off of y'all to see if I get any appreciation.

Too bad you had to use scruffy old nuts on the prop!
Larry