REFLECTOR:Static Port adjustment

[Scott]

Been trying to get this static port problem nailed down.

The symptom being I indicate 400 ft higher than I really am at cruise 
speeds, my airspeed also indicates higher than it really is at cruise. The 
problem is barley noticeable but is there at low speeds.

I have been using Scott Swings method to test it as he wrote about in the 
last VV.  You set your altimeter to the field elevation prior to take off, 
then do a low pass, I try for 40 ft,  down the runway at max cruise.  See 
what your altimeter indicates and it will let you know your static port is 
adjusted correctly for cruise.   Mine indicating 400 ft high when I started 
this investigation.

First I had to determine if my static system was tight.  I had done this 
over a year ago when I had the static system certified but I'd worked on 
various parts of the back panel and could have jostled something loose.  My 
initial check showed a huge leak.   I then preceded to hook up each 
instrument in line from the static port out, verifying the connections and 
the instrument.  I found a hose that had a rough surface inside the tube 
end and replaced it. That made it a tad better.  Finally got to the last 
instrument in the line, the VSI and it had a small internal leak.

The VSI was only 6 years old when the panel was built by the 
electronics  shop at the factory, but it is one of those cheap ass Chinese 
instruments which  is a crime to sell to anybody in my opinion.  My 
airspeed indicator of same vintage and sold and installed by the same 
shop(at the Velocity Factory) had to be replaced last year because of 
internal leakage.  If your contemplating hiring this guy  to do your panel 
make it clear you don't want trash installed in your panel.

I ordered a United Instruments VSI and waited to see what a non-leaking 
static system would do.

After installing the new  VSI I tried it out and my altimeter was now 300 
ft off instead of 400.  Better but certainly not according to Hoyle.

I decided to grind the aluminum trip strip in front of my  3 vertically 
aligned static ports down as that is what I read was the cure for, too low 
of air pressure at the port.  There is a very long and detailed discussion 
on this topic on one of the canard email lists.

I got about halfway  done and it fell off, I had ground through the rivet 
heads and it wasn't glued on.  I replaced it with one about 1/3 as thick, 
new thickness was 032 aluminum.    Tried that out and I was now 200 feet high.

Hmm..  I pulled it off and tried no trip strip at all.   Now 100 ft 
high!  Better and better.  And doing a lot of flying which is making my 
engine last longer , right!

So I now put a double layer of duct tape behind the static port holes, this 
was mentioned as a possible place I would need to put the strip in the 
discussion I had read.

Tried it and I was now 40 ft low.   Feeling good..   Closing in on an 
accurate altimeter and airspeed indicator at cruise.

I then cleaned up the area where the old trip strip was mounted, there was 
paint edges and a depression in the glass where it was mounted so I micro'd 
that to make it al smooth.

Once that drys I'll try a piece of  aluminum tape behind the static 
port,  I don't need much so I think a thin metal tape that will last should 
do the trick.

Scott