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ALtimeter adjustment
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kerrjohna(at)comcast.net
Guest

Posted: Mon Aug 21, 2006 8:55 am Post subject: ALtimeter adjustment

Some of you may remember a thread a couple of months ago regarding a mystery marker(bug) that moved around the circumference of a old altimeter.  While at OSH I asked one of the intrument dealers there about it.  Apparently, it is a pressure altitude indicator used on (much) higher performance aircraft.

  

 [quote]-------------- Original message -------------- 

From: Marco Menezes <msm_9949(at)yahoo.com> 

 Thanks for asking that Gary. I have the same issue with my altimeter. Seems like I'm adjusting it constantly to the GPS. It's so far out of whack that barometric pressure reading has vanished form Kollsman window. I tried removing the little screw next to the Kollsman adjustment knob (figuring it was a calibration screw) and spent the next hour putting the little parts back in that came shooting out.

  

 By the way. I've also experience pilot side tank emptying faster. I have noticed that fuel cap on that side vents better than the other one. Don't know if that's the cause or a tendency to fly left wing high. I'm going to swap caps and see if it makes a diff. 



Algate <algate(at)attglobal.net> wrote:

 [quote]    v\:*  {behavior:url(#default#VML);}  o\:* {behavior:url(#default#VML);}  w\:* {behavior:url(#default#VML);}  .shape {behavior:url(#default#VML);}   <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />   st1\:*{behavior:url(#default#ieooui) }           Thanks Don and Shane,

  

 I think that you are both probably right and I am probably chasing red herrings. As I am new to this plane I am probably just being over critical. I knew my last Kitfox inside out and trusted it implicitly – I guess I am just going to have to build up the same confidence level with this one.

  

 Another question – I found an adjustment for my VSI but not for the altimeter – is there a user friendly way to adjust these or is it an instrument technician job. My altimeter reads almost 600ft out !

  

  

 Regards

  

 Gary Algate

  

    

 From: <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Shane Sather

Sent: Monday, August 21, 2006 9:51 AM

To: kitfox-list(at)matronics.com

Subject: Re: RE: Kitfox-Fuel Flow



  

  Gary I notice the same difference on my Light 2 also but not to the same extent. The pilot side always goes lower first. This has been noted by many others too and I don't recall that there was any real solution for this



   



  Shane. 



 [quote]  ---

smokey_bear_40220(at)yaho
Guest

Posted: Mon Aug 21, 2006 10:23 am Post subject: ALtimeter adjustment

Yes, mystery solved,



Kurt S.



Do not archive



--- kerrjohna(at)comcast.net wrote:



 	  Quote: 	
		   Some of you may remember a thread a couple of months

 ago regarding a mystery marker(bug) that moved

 around the circumference of a old altimeter.  While

 at OSH I asked one of the intrument dealers there

 about it.  Apparently, it is a pressure altitude

 indicator used on (much) higher performance

 aircraft.


	


__________________________________________________

smokey_bear_40220(at)yaho
Guest

Posted: Mon Aug 21, 2006 10:56 am Post subject: ALtimeter adjustment

Yes, don´t remove the altimeter screw.  I did that

too.  Just loosen. It takes a bit of jiggling to

disengage the gears and the same to get them

reengaged.  I believe you set the altitude first, then

pull the knob to reset the window only, then push

while wiggling to reengage the gears and then tighten

the screw.



Kurt S.



__________________________________________________

mike
Guest

Posted: Mon Aug 21, 2006 11:03 am Post subject: Re: ALtimeter adjustment

I would never adjust my vertical to the GPS, why it's not all that accurate.  I can fly around the larger airports and fall within 100ft., but if I leave the area and fly lets say outside 25 miles from the airport, the veritical is 300ft off.  Another concern is where you are pulling the static port, under the dash and the altimiter is off about 100, outside the plane is generally most accurate.  I've played between inside and outside and both vertical and airspeed is affected a bunch.

msm_9949(at)yahoo.com
Guest

Posted: Mon Aug 21, 2006 11:39 am Post subject: ALtimeter adjustment

Static port is on left fuse toward the tail. All other static instruments work fine. I'm pretty sure altimeter just needs a little calibration.

   

  do not archive



kitfoxmike <kitfoxmike(at)yahoo.com> wrote:

  [quote]--> Kitfox-List message posted by: "kitfoxmike" 



I would never adjust my vertical to the GPS, why it's not all that accurate. I can fly around the larger airports and fall within 100ft., but if I leave the area and fly lets say outside 25 miles from the airport, the veritical is 300ft off. Another concern is where you are pulling the static port, under the dash and the altimiter is off about 100, outside the plane is generally most accurate. I've played between inside and outside and both vertical and airspeed is affected a bunch.



--------

kitfoxmike

kitfox4 1200 		[url=http://us.rd.yahoo.com/evt=43256/*http://advision.webevents.yahoo.com/mailbeta] All-new Yahoo! Mail [/url]- Fire up a more powerful email and get things done faster. [quote][b]

kerrjohna(at)comcast.net
Guest

Posted: Mon Aug 21, 2006 11:52 am Post subject: ALtimeter adjustment

has anyone had a problem with the recommended location of the static port on a Classic IV?  On take off, altitude drops +/- 100 feet as I get near rotation speed.

  

 John Kerr

  

 [quote]-------------- Original message -------------- 

From: "kitfoxmike" <kitfoxmike(at)yahoo.com> 



[quote] --> Kitfox-List message posted by: "kitfoxmike" 

 

 I would never adjust my vertical to the GPS, why it's not all that accurate. I 

 can fly around the larger airports and fall within 100ft., but if I leave the 

 area and fly lets say outside 25 miles from the airport, the veritical is 300ft 

 off. Another concern is where you are pulling the static port, under the dash 

 and the altimiter is off about 100, outside the plane is generally most 

 accurate. I've played between inside and outside and both vertical and airspeed 

 is affected a bunch. 

 

 -------- 

 kitfoxmike 

 kitfox4 1200 912ul speedster 

 http://www.frappr.com/kitfoxmike 

 rv7 wingkit 

   reserv   WIKI    [quote][b]

AMuller589(at)AOL.COM
Guest

Posted: Mon Aug 21, 2006 12:05 pm Post subject: ALtimeter adjustment

If your altitude changes from runway altitude during acceleration for  takeoff and rotation your static port is in a bad location. Ours is a dual port  system flushmounted on the fuselage just under each door just below where a  pilots hand would be if the arm was hung out the doors. The GPS altitude is not  accurate enough for legal altimeter settings and if you monitor it in a  stationary position you will notice it varies quite a bit. Here in Houston at 23  ft msl it has varied a hundred feet or so If your altimeter is in error by plus  or minus 75 feet it should not be used.

  [quote][b]

msm_9949(at)yahoo.com
Guest

Posted: Mon Aug 21, 2006 12:38 pm Post subject: ALtimeter adjustment

Actually, mine was a bit more complicated. Instrument had to come out of the airplane. The screw on face of instrument had to come out completely and the pin it screwed into, disengaged from the knob post before the knob would pull out. Pulling knob out while turning it moves the Kollsman window altimeter reading, so set your known elevation first, then pull out knob and set altimeter. 

   

  Now, does anyone know how to calibrate an rpm gauge? I have an ACS cheapo that reads 500 with the engine shut down.



kurt schrader <smokey_bear_40220(at)yahoo.com> wrote:

  [quote]--> Kitfox-List message posted by: kurt schrader 



Yes, don´t remove the altimeter screw. I did that

too. Just loosen. It takes a bit of jiggling to

disengage the gears and the same to get [quote][b]

mike
Guest

Posted: Mon Aug 21, 2006 1:28 pm Post subject: Re: ALtimeter adjustment

The only way I would mess with an my vertical is to set altimeter and then adjust to known altitude on the ground.  If there are any other problems, send the unit in for repairs or replace.  My static is where skystar put it in the plans.  I also have a transponder and my altitude is what shows on the radar.  Well, within 100ft. anyway.  I don't care if it's that percise.  But the main thing is it doesn't vary while I'm flying.  But the Gps does.  Like I said earlier, the Gps will loose out the farther I get away from the big airport.  I think either my Gps needs to be hooked to an external entenna, or the accuracy is dropped  as you get away from the big airports.  You know, classC and classB airports.

Float Flyr

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

Posted: Tue Aug 22, 2006 4:51 am Post subject: ALtimeter adjustment

Thanks for the reminder.  I had been planning on resetting my Altimeter for

a long time now and never seemed to get around to it.  While I was at it I

did the VSI the next step is a compass swing... Not too easy on floats.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

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

Posted: Tue Aug 22, 2006 5:08 am Post subject: ALtimeter adjustment

If the tach is mechanical  then it's done by internally adjusting the tension on screws.  Some have  spring tension adjusters some have to replace the springs.  these units are  lovely to look at but are quite heavy as are the drive cables etc.  when  new they are known to be quite accurate.

  

 If it's early electrical  it may have a variable resistor that can be adjusted.  On these meter  type tachs you may also have to set the "0" mark on the face of the meter.   Before fooling with any internal settings I would check on the zero set (it's a  little screw at the base of the meter hand) first.  disturbing any of the  internal resistors will affect the linearity of the instrument.  Ever  calibrate a tach???? Me neither.

 If the tach hand swings through  an arc of more than 90deg. there may also be a gear network associated with the  pointer.  This is a place where friction can occur making the tach a bit  sluggish.  Lubricating those gears and pivots is not  recommended.

  

 If the tach is digital it's  probably right on but you may have to filter noise off the tach line.  Some  times ignition noise on the tach input line can be read as extra pulses by the  tach making it read high.  Check the archives  for fixes.  some have added resistors to the input line to filter  out noise.

  

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

dave(at)cfisher.com
Guest

Posted: Tue Aug 22, 2006 5:23 am Post subject: ALtimeter adjustment

Hi ,

  

 On tachs-  get a tiny tach.  They have  proven most accuarte as they measure off the spark plug wire. 

 ACS tachs  - I do not know but I do know that  Rotax tachs can read erractic as hell. 

  

  

 Dave 

 47 years old

 582  IV

 [quote]   ---

Float Flyr

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

Posted: Tue Aug 22, 2006 5:28 am Post subject: ALtimeter adjustment

Be careful with the transponder altitude encoder.  



The encoder is always set at 29.92 for IFR readings.  That way all aircraft

encoders will read the same altitude in a given location.  Well that's the

idea any way.  When you get an altitude report form FSS they are reading

back to you the info your encoder has sent them mode "C".  



At VFR altitudes deviations from 29.92"hg. Will give discrepancies in your

encoder info.  A problem with this info is all it requires is for a partial

blockage of a static port to occur and the info reported to you by FSS will

be wrong.



If you subscribe to the GPS nav systems that airports are installing. Then

your altitude should be corrected for several miles around that airport.

Other than that I wouldn't trust it at all.  GPS is a great system except it

is military controlled and we get dependant on it.  For short distances I

love to fly VFR I have even navigated to an extent by the sun and got close

enough to see my destination.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

mike
Guest

Posted: Tue Aug 22, 2006 6:08 am Post subject: Re: ALtimeter adjustment

What's the big deal on altitude any way, I fly out the window, and if your going into an off field (remote landing) landing you have no idea what the altitude is, and that GPS should not be trusted for this, for reasons I mentioned earlier.  You need to know your altitude by looking out the window.  The other day I flew into such an air stip that my wife was sitting in the right seat holding on and just figiting the whole way down.  I cleared all trees by about 20ft. but she couldn't take the closeness or the look of what I was doing.  That's where doing short landings at your airport comes in handy.  You can judge your height and if needed glance down at the altitude for reference to make yourself better at it.  As far as the encoder, I use that as a reference to prove that the altitude indicator does not change, but the Gps will vary for reference, if that makes sense.  I never rely on the encoder for accuracy, just to show that the altitude indicator isn't loosing accuracy through the flight.  THat's why you always give your altitude when getting clearance with atc, so that things can be zero'd so to speak with the controller.

Float Flyr

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

Posted: Tue Aug 22, 2006 8:01 am Post subject: ALtimeter adjustment

Good Idea...I did that last  year!  works great for me.

  

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Tue Aug 22, 2006 12:38 pm Post subject: ALtimeter adjustment

Noel-

I was advised to fly the plane, and align it with hedge rows....N-S and 

E-W.  I tried this last night, but some of the rows curved, so I'm not 

sure how accurate this advice is. I first tried to set the compass 

using the GPS, but was tracking wrong for this to work. If you set it 

on the ground, how do you make sure the plane is exactly aligned with 

the compass rose? And in your case, floats, ??????



Lynn



On Tuesday, August 22, 2006, at 08:51  AM, Noel Loveys wrote:



[quote] 



 Thanks for the reminder.  I had been planning on resetting my 

 Altimeter for

 a long time now and never seemed to get around to it.  While I was at 

 it I

 did the VSI the next step is a compass swing... Not too easy on floats.



 Noel



> --

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Float Flyr

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

Posted: Tue Aug 22, 2006 4:34 pm Post subject: ALtimeter adjustment

I forgot to mention alignment on wheels without a compass rose.  Well you

are supposed to use a calibrated reference compass to set out a compass rose

before you start or use a reverse heading sighting compass to set the

heading of the plane.  Head the plane North Mag, Zero the compass until the

card points North (zero deviation).  Then turn the plane to the East and set

the compass E-W to read 90 degrees.  Now turn the plane south and remove

ONLY HALF of the correction to make the compass read South. You guessed it

turn to the west and remove  ONLY HALF the E-W correction that would make

the compass read West.  Now turn the plane to the North again and read the

compass that reading is what is supposed to be on the compass correction

card. Keep turning the plane in 45 deg increments recording the compass

readings at each point. Prepare the compass correction card.



Points to remember.... 



 If you use the special sighting compass (Also calibrated) that reads in

reverse be sure to "shoot" the plane's direction from more than 30' in front

of the plane.  



The compass should be level while making the corrections and the readings.

You can either jack up the tail or just swivel the compass to do this.  An

in dash installed compass will require you to raise the tail at each

direction.



Use a non ferrous screw driver to make the adjustments. (Thought I'd miss

that one didn't you.)



There is one sure way to tell that a compass swing has been done with the

sole use of a BIC pen.  The for 0 deg, head 0deg is a real give away. (If

you are going to cook the books at least do it right.)



Engine should be running (over 1000rpm.) and normal in flight electrical

equipment should be turned on.



Nothing too difficult until you have to do it on floats.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

AMuller589(at)aol.com
Guest

Posted: Tue Aug 22, 2006 4:46 pm Post subject: ALtimeter adjustment

compass swings: after the major headings are logged use the D.G. inflight  to calibrate the individual 10 deg if desired.

  [quote][b]

Float Flyr

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

Posted: Tue Aug 22, 2006 5:04 pm Post subject: ALtimeter adjustment

To swing a compass properly on floats requires that you know the area you

are setting up in very well and that you have almost glassy water

conditions.  You have to pick your headings and then while under way make

the compass adjustments.  I suppose it could be done with an anchor attached

to the tail of the plane then use the rudder to set up directions.  The

problem is you are supposed to line the aircraft up accurately and you are

supposed to operate the engine and in flight electrical equipment.  The only

way I can see it being done is to have two persons doing the swing, one to

handle the plane and one to make the adjustments to the compass.



Now for the truth....



The decision on what is straight is subjective. Very few planes are

completely symmetrical.  What the pilot perceives  as straight is also

subjective and of course there is the whole question of parallax

correction.....    The ability to hold a heading within a couple of degrees

on a magnetic compass in a noisy and some what busy or bumpy cockpit is

difficult.  For most people if the compass points "more or less" north it's

ok.  I know of pilots who have never even looked at their compass cards even

though there has to be a recent compass card on board here in Canada and a

compass swing is part of an annual inspection.  I doubt they ever use their

compasses.  Now with the advent of GPS....



The obvious short cut is to do the swing while the plane is on the trailer

of course you will have to accept some error.  Unless you know of some one

who has a composite trailer.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

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

Posted: Tue Aug 22, 2006 6:23 pm Post subject: ALtimeter adjustment

The work is in adjusting the four primary  cardinal points

  

 All you need is a DG and something to  reference it to.  Neat idea.

  

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

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