Static Port

How would it work to make the static port a half dollar size round 3/32 or 1/8 inch
aluminum disk riveted to left side of boot cowl? If I remember correctly Cessna uses
a static port similar to this. Where is the standard supercub static port located and what
drill size is the orfice?

Thanks
Jim Miller

This is going to place it right behind the engine cowl that is bowed out and make for for turbulent air. A static source need to be on a smooth surface with and uninterrupted airflow.

Each model of plane has it's differences which effect static port locations and sometimes take a lot of experimentation to find the best location. As to your question of the boot cowl like on a Cessna, my first response would be, that will not be good on a Cub. The Cessna cowl blends into the boot area with no cooling air openings. The Cub cowl is open with airflow inconsistencies. A static port in this area would be sensing engine cooling air and would likely vary a lot with different speeds and attitudes. For example when my 185 was painted the half dollars were painted over with some paint in the hole. It cruised 20 knots faster on the way home. The paint had to be completely removed from the half dollars before the speed went back to normal. The Cessna has one on each side of the boot which are connected inside to balance the pressure from both sides of the fuselage. When mounted anywhere on a fuselage generally two are required to stabilize the pressure signal. Some Cubs are just vented under the panel and some have the static port collocated with the pitot tube under the wing. I am using a surplus Kollsman pitot/static head mounted under the wing outboard of the jury struts on my Backcountry Cub. It is not finished so I can't give you a pirep.

I thought Supercub.org was the "Static Source"?????:roll::lol:

Sorry, couldn't resist....

MTV

I tore down a Tripacer years ago and found a static port attached to one of the bottom belly stringers. I think it was aft the baggage.

Thanks for the replies. My Colt is like Planenut stated, two static ports tee"d together on bottom rear fuselage.
I think I will go with putting it on the wing near the pitot.

This:
http://www.aircraftspruce.com/catalog/inpages/pitot15144.php
is a sample of an under the wing pitot/static tube assembly which I have seen under Cub wings. It should be easy to make out of a couple pieces of tubing. I have also seen others which provide more vertical separation between the two tubes than that which is shown.

This is my solution; static line vented to cabin air. In about the center of the image you can see an airline filter. It has a male pipe thread on it and is screwed into the fitting on the static line. The filter is an industrial airline filter that cost just $5 or so. The red capped fitting right below it will be the static source for the transponder's altitude encoder.

Spinner2 wrote:

"The filter is an industrial airline filter that cost just $5 or so. The red capped fitting right below it will be the static source for the transponder's altitude encoder."

Sir, would you please provide the source and part number of the filtershown in the picture above?

Many thanks,

Andy Mutzig

Jim Miller said:

Thanks for the replies. My Colt is like Planenut stated, two static ports tee"d together on bottom rear fuselage.
I think I will go with putting it on the wing near the pitot.

Click to expand...

I'm not so sure thet you have a choice in the matter. Your static system as installed is what the factory approved. To do something different may require FAA involvement - even if it a VFR only type airplane.

Why do you want to change the original design in the first place?

John Scott

Why do you want to change the original design in the first place?

My take on Super Cub instruments is that they are probably secondary sources of information to start with. The first Cubs had static sources at the back of each pressure instrument, and opening a door or window would have a slight effect.

But there are lots of folks who want to modify perfectly good aircraft to fit their vision of what a good Cub ought to be. Cub Crafters does it all the time. I am personally not in favor of converting J-3s to PA-18 wannabees, but it is the owner's choice, and folks do it all the time. See the thread on trim systems.

I would guess that whatever you do to a Super Cub static system will not change the basic airplane one whit. Have at it.

bob turner said:

and opening a door or window would have a slight effect.

Click to expand...

'Zactly. I (honestly) wonder what's the diff, if your altimeter is off a bit. There MUST BE something more important to fret about.
Maybe someone should invent a downwind turn indicator.

Like Mike, here I was thinking we were getting into another discussion about downwind turns in a Husky...

Looks like I need to go work on another sno-go... have to out before Logan's is done.

I still like the front jury strut for aspd and pitot. When you take the gas tank cover off you can run the tube all the way with no splices and can work on it easy. Mine is out past the lift struts attach but the next time im going for the strut setup. David Jaranson sent me a picture of how he had his on the front jury strut, i liked it. Wished i would have saved the picture. Had the tubing come right down through the wing at the jury strut a few inches before sliding over the pitot tube. Airspeed the same way.