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Static port trouble

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Giovanni Day

Joined: 05 Jul 2007
Posts: 43

Posted: Sun Jul 08, 2007 7:37 pm Post subject: Static port trouble

I put my static port in the back just in front of the tail on the pilot side. My vertical speed reads that I am descending all the time and the airspeed reads low. I remove the static and they get better but the vertical speed is dampened for some reason. The air speed is not far off with the cockpit pressure. Where are most of you getting your static air?

_________________
_______________________________________
Giovanni Day
Model 4 speedster 912

lcfitt(at)sbcglobal.net
Guest

Posted: Sun Jul 08, 2007 9:01 pm Post subject: Static port trouble

Giovani,



My static port is essentially where yours is - per the Skystar bulletin at 

the time.  My airspeed is pretty accurate, but runs lower than friends I fly 

with.  I don't find it a problem as all the speeds I use - approach, stall, 

etc are relative to what the ASI reads error and all.  There is a small 

screw on the face of the VSI that I can set to zero when straight and level. 

I adjusted it a time or two by necessity.



Lowell Fitt

Cameron Park, CA

Model IV-1200 R-912 UL Warp

1998 870 hrs.

---

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Sun Jul 08, 2007 11:08 pm Post subject: Static port trouble

 	  Quote: 	
		   From: Giovanni Day [thedays(at)mchsi.com]

 What where are most of you getting your static air?


	


Hello Giovanni,

As Lowell says, your static port position is what Skystar (and Denney, before) recommended. I have mine at the same place although I read an average of 5 MPH higher speed. My VVI is just fine and I have a problem to understand how yours is showing all the time a descent. If I am not mistaking, the VVI is a "bleeding" instrument, i.e. it shows a change in pressure that resets with time when the pressure become constant. If you show a constant descent, it means that it is constantly changing pressure ... which is impossible. So I don't think your static port is the cause of your "constant descent" but maybe your instrument needs calibrating.



Cheers,

Michel Verheughe

Norway

Kitfox 3 - Jabiru 2200

<pre><b><font size  color="#000000" face="courier new,courier">

_________________
Kitfox 3 - Jabiru 2200

l.morris(at)tx.rr.com
Guest

Posted: Mon Jul 09, 2007 5:52 am Post subject: Static port trouble

I installed a pitot/static tube (Aircrraft Spruce $15) with is suppose to do away with those problems.---Leon Morris/Classic 4/50%/Flower Mound,TX         Giovanni Day <thedays(at)mchsi.com> wrote: 

 	  Quote: 	
		   

 

 I put my static port in the back just in front of the tail on the pilot side. My vertical speed reads that I am descending all the time and the airspeed reads low. I remove the static and they get better but the vertical speed is dampened for some reason. The air speed is not far off with the cockpit pressure. What where are most of you getting your static air?

 

 --------

 _______________________________________

 Giovanni Day

 Model 4 speedster 912

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=122801#122801

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Mon Jul 09, 2007 6:16 am Post subject: Static port trouble

At 08:37 PM 7/8/2007, you wrote:

 	  Quote: 	
		  What where are most of you getting your static air?


	


Mine is in your location and my airspeed reads about 10% low. My 

altimeter and encoder has been checked by the avionics shop and found 

to be satisfactorily accurate so my airspeed error is in the pitot 

side. (My pitot is left wing, near the strut outboard fitting, about 

6" below and 10" behind the leading edge. It's been checked for leaks 

so the problem is position error.)



The "damping" you see in the cockpit mode is likely a fairly well 

sealed cockpit slowly bleeding air in and out. (Hard to imagine in a 

IV!) Michel and Lowell have already mentioned that the VSI just needs 

adjustment. I'm assuming, of course, that the VSI reads low on the 

ground, as well.

Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Jul 09, 2007 6:41 am Post subject: Static port trouble

I have a single port at what is almost the widest  part of the plane (just in front of the door)  I have considered putting a  second port opposite the existing one to balance the static port in a  slip.



Only problem with my location is I have to disconnect it every time  I want to remove the lower main cowl.  ( model III-A)



 

[img]cid:297034014(at)09072007-12AA[/img]  

 Noel Loveys, RPP, AME intern

 Campbellton, Newfoundland, 

 Canada

 Kitfox Mod III-A, 582, B box, Ivo IFA

 Aerocet 1100s

 noelloveys(at)yahoo.ca (noelloveys(at)yahoo.ca)

 

 

 Do not archive

 

 

 

[quote] --

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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Giovanni Day

Joined: 05 Jul 2007
Posts: 43

Posted: Mon Jul 09, 2007 7:15 am Post subject: Re: Static port trouble

Thanks for the replies.

I believe my problem is that the static port is under a constant pressure. For some reason it is catching air like a pitot tube. I have checked to make sure the pitot and static are not reversed. 



I will zero the VSI in level flight and see what it does then. As suggested I will try and  not concern myself with the airspeed error as it is a constant error so all my V speeds will be based on indicated not actual. Heck I have a Garmin 296 and it gives a good VSI and ground speed indication but I just wanted to have the VSI close. 



My Static port is very thick like an Oreo cookie and I am now concerned this is the problem. I will take a photo and post it this evening for everyones opinion.



Thanks again.

_________________
_______________________________________
Giovanni Day
Model 4 speedster 912

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Jul 09, 2007 11:46 am Post subject: Static port trouble

If your static and pitot were reversed the ASI  would try to read negative...  VSI would also try to reverse.  I  did see one plumbed this way and mentioned it to the guy who couldn't believe he  made so simple a mistake.... Luckily he didn't try to fly like  that.



Calibrate the VSI on the ground.  The best place to know the  plane is neither going up or down.  Also easier to do than fly the plane  and fiddle with a screwdriver at the same time. 



 

[img]cid:848473919(at)09072007-12B1[/img]  

 Noel Loveys, RPP, AME intern

 Campbellton, Newfoundland, 

 Canada

 Kitfox Mod III-A, 582, B box, Ivo IFA

 Aerocet 1100s

 noelloveys(at)yahoo.ca (noelloveys(at)yahoo.ca)

 

 

 Do not archive

 

 

 

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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

kirkhull(at)kc.rr.com
Guest

Posted: Mon Jul 09, 2007 2:30 pm Post subject: Static port trouble

If it is reading a constant decent you might have a leak in the case.  Disconnect the static line so the inst is just open to the cabin and go flying.  If it still shows a constant decent it is a bad unit  

   

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Noel Loveys

 Sent: Monday, July 09, 2007 2:42 PM

 To: kitfox-list(at)matronics.com

 Subject: RE: Re: Static port trouble  

  

   

If your static and pitot were reversed the ASI would try to read negative...  VSI would also try to reverse.  I did see one plumbed this way and mentioned it to the guy who couldn't believe he made so simple a mistake.... Luckily he didn't try to fly like that.

 

 Calibrate the VSI on the ground.  The best place to know the plane is neither going up or down.  Also easier to do than fly the plane and fiddle with a screwdriver at the same time.   

[img]cid:image001.jpg(at)01C7C24E.AC7847F0[/img]   

Noel Loveys, RPP, AME intern  

Campbellton, Newfoundland,   

Canada  

Kitfox Mod III-A, 582, B box, Ivo IFA  

Aerocet 1100s  

noelloveys(at)yahoo.ca (noelloveys(at)yahoo.ca)  

Do not archive  



 

 > -----Original Message-----

 > From: owner-kitfox-list-server(at)matronics.com

 > [mailto:owner-kitfox-list-server(at)matronics.com (owner-kitfox-list-server(at)matronics.com)] On Behalf Of

 > Giovanni Day

 > Sent: Monday, July 09, 2007 12:46 PM

 > To: kitfox-list(at)matronics.com

 > Subject: Re: Static port trouble

 >

 >

 > --> Kitfox-List message posted by: "Giovanni Day" <thedays(at)mchsi.com>

 >

 > Thanks for the replies.

 >

 >

 > I believe my problem is that the static port is under a

 > constant pressure. For some reason it is catching air like a

 > pitot tube. I have checked to make sure the pitot and static

 > are not reversed.

 >

 > I will zero the VSI in level flight and see what it does

 > then. As suggested I will try and  not concern myself with

 > the airspeed error as it is a constant error so all my V

 > speeds will be based on indicated not actual. Heck I have a

 > Garmin 296 and it gives a good VSI and ground speed

 > indication but I just wanted to have the VSI close.

 >

 > My Static port is very thick like an Oreo cookie and I am now

 > concerned this is the problem. I will take a photo and post

 > it this evening for everyones opinion.

 >

 > Thanks again.

 >

 > --------

 > _______________________________________

 > Giovanni Day

 > Model 4 speedster 912

 >

 >

 >

 >

 > Read this topic online here:

 >

 > http://forums.matronics.com/viewtopic.php?p=122858#122858

 >

 >

 >

 >

 >

 >

 >

 > ===========

 > Kitfox-List http://www.matronics.com/Navigator?Kitfox-List

 > ===========

 > bsp;  available href="http://forums.matronics.com">http://forums.matronics.com

 > ===========

 >

 >

 >

 >

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Giovanni Day

Joined: 05 Jul 2007
Posts: 43

Posted: Mon Jul 09, 2007 2:35 pm Post subject: Re: Static port trouble

Let me clarify. It reads constant but variable decent when in flight. Not much variation though. If I disconnect the static in flight it reads 0 and only varies about 100 fpm.

_________________
_______________________________________
Giovanni Day
Model 4 speedster 912

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Mon Jul 09, 2007 2:49 pm Post subject: Re: Static port trouble

 	  Quote: 	
		  Let me clarify. It reads constant but variable decent when in flight. 	


 Am I the only one that found that line funny? Did you mean to say that it constantly reads a descent but the rate varies? I don't mean to be cheeky but I have some interest in this thread as I too am trying trying to sort out some vacuum system quirks.

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

Giovanni Day

Joined: 05 Jul 2007
Posts: 43

Posted: Mon Jul 09, 2007 2:54 pm Post subject: Re: Static port trouble

You got it. When in flight it consistently give an 600-800 fpm decent.   LOL However when the airplane is at rest it reads zero.

_________________
_______________________________________
Giovanni Day
Model 4 speedster 912

smokey_bear_40220(at)yaho
Guest

Posted: Mon Jul 09, 2007 3:25 pm Post subject: Static port trouble

--- Giovanni Day <thedays(at)mchsi.com> wrote:



 	  Quote: 	
		   You got it. When in flight it consistently give an

 600-800 fpm decent.  [Embarassed] LOL However when

 the airplane is at rest it reads zero.


	


 	  Quote: 	
		   Giovanni Day

 Model 4 speedster 912


	


My VSI also reads a descent in flight.  It is adjusted

at the upper limit to get zero on the ground, but

reads 150 ft/min descent when level in flight.  Pretty

close compared to yours, but not perfect either.



In your case, I think it may be static problems if

your ASI is off too.  It would also read a wrong

altitude, depending on speed, but that is harder to

confirm.  If only the VSI is off, it is probably the

gauge.  A static fault anywhere in the system should

throw off all gauges that use it.



The static checks performed by inspectors on your

gauges do not account for position error, only gauge

and line quality.  Only blowing air over the port will

check for position error.



You might try tapping a small air damn just in front

of your static port.  Something 1/4 inch high and an

inch across about 1/2 inch in front of your port. 

This will create a boundry layer over the port and

might make a difference.  If it does, you can try

different sizes of little damn until you get one just

big enough to give you accuracy over your speed range.

 Then perminately install it.



Smallest change you can make, if it is positon error. 

I have seen this on several production planes to

correct their system.



Kurt Schrader

S-5/NSI turbo

Florida and Panama

       

Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out.

http://answers.yahoo.com/dir/?link=list&sid=396545469

lcfitt(at)sbcglobal.net
Guest

Posted: Mon Jul 09, 2007 4:13 pm Post subject: Static port trouble

List



I replied to Noel off list regarding my reason for adjusting the centering 

screw in flight but recent posts suggest a list wide response is 

appropriate. I just checked my VSI and it shows a 50 ft per minute descent 

sitting in the hanger - thank goodness for concrete floors.



Since I rarely sit in the airplane on the ground looking at needles - engine 

instruments excepted, I have found it more useful to have the VSI more 

accurate while flying so adjusting it to zero in that invironment works best 

for me. It's not really easy to do, but after a tweak or two it satisfies. 

I do carry one of the small jewelers screwdrivers in one of the pencil clips 

of  my kneeboard.



Lowell Fitt

Cameron Park, CA

Model IV-1200 R-912 UL Warp

1998 870 hrs.

I had to adjust mine in flight---

Giovanni Day

Joined: 05 Jul 2007
Posts: 43

Posted: Mon Jul 09, 2007 6:13 pm Post subject: Re: Static port trouble

I did a little flying this afternoon. Flew with static to ASI only and it was within 3-5 mph of the gps. I have a EIS with alt. an vsi. I rigged a connection of its electronic sensor to the static and it worked properly. I then connected the mechanical vsi (MVSI)and the EIS. The EIS seemed correct when compared to the GPS but the MVSI was way off as usual. I tried adjusting the MVSI and it seemed to improve. When I pulled the power to land after adjusting it, it went crazy. I think I will locate a known good MVSI and see what it reads.

_________________
_______________________________________
Giovanni Day
Model 4 speedster 912

smokey_bear_40220(at)yaho
Guest

Posted: Mon Jul 09, 2007 7:32 pm Post subject: Static port trouble

--- Giovanni Day <thedays(at)mchsi.com> wrote:



 	  Quote: 	
		   I did a little flying this afternoon. .... I think I

will locate a known good MVSI and see what it says.
	




 	  Quote: 	
		   Giovanni Day

 Model 4 speedster 912

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


I think you got it narrowed down pretty well.



Kurt S.

do not archive

       

Got a little couch potato? 

Check out fun summer activities for kids.

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Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Mon Jul 09, 2007 8:52 pm Post subject: Static port trouble

At 03:54 PM 7/9/2007, you wrote:

 	  Quote: 	
		  You got it. When in flight it consistently give an 600-800 fpm 

decent.  [Embarassed] LOL However when the airplane is at rest it reads zero.


	


I had to go back to my books to confirm how a VSI works, but if I'm 

not mistaken you could get this error if you had a leak in the case. 

This would allow the low pressure cockpit air to lower the case 

pressure constantly, relative to the static port, causing the 

appearance of a descent. It's not entirely unlikely; I had a leak in 

my altimeter case that took me days to find. I finally found it by 

applying a very slight vacuum using a small hand vacuum source, (used 

to bleed brakes.) The vacuum would decay over time, indicating a 

leak. I then applied the vacuum and ran a bead of thin cyanoacrylate, 

(super glue,) where the bezel met the glass. The cyanoacrylate was 

ingested into the leak and sealed it.

Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

jeburke94je(at)hughes.net
Guest

Posted: Tue Jul 10, 2007 4:56 am Post subject: Static port trouble

congrats!!!!!

---

kirkhull(at)kc.rr.com
Guest

Posted: Tue Jul 10, 2007 4:59 am Post subject: Static port trouble

That is correct.  A leak in the case will cause it to read a constant

decent.  to check this unhook the static line and go flying.  If it still

has the same problem then it is not the static port but is most likely a

leak in the case.  If I remember correctly the Kitfox will not read

correctly with out a static system hooked up but it should be close.

--

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