Today's Message Index:
----------------------
1. 09:40 AM - Re: Checking tanks (Leland)
2. 09:47 AM - Cowl fitting (Leland)
3. 01:47 PM - Re: Bare Aluminum Cleaner (Jen Coull)
4. 07:13 PM - Gear leg pictures (Andy Karmy)
5. 08:40 PM - pneumatic squeezer tips? (Paul Eastham)
Message 1
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| Subject: | Re: Checking tanks |
--> RV9-List message posted by: Leland <Federigo@pacbell.net>
I used a water manometer in testing for fuel tank leaks. (A water
manometer is just a water-filled loop having one end connected to the
fuel outlet and the other end open to the air.) Since the temperature in
my garage varies a lot, it was useful to know how much the pressure
changes in a fuel tank as the temperature varies. At sea level and a
temperature of 68 degrees Fahrenheit, the change in pressure as measured
with a water manometer is very nearly 3/4 of an inch of water for each
Fahrenheit degree of change.
For other conditions, the perfect gas equation can be used. Using the
perfect gas equation shows that the change in pressure per change in
temperature is approximately equal to starting pressure divided by the
starting temperature, P/T, where the pressure P is conveniently measured
in inches of water column and the temperature T is measured in degrees
Kelvin. Kelvin temperature is equal to the temperature in Celsius (often
called Centigrade) degrees plus the number 273. An atmospheric pressure
of 14.7 psi is equal to 407 inches of water (and it is also equal to
29.92 inches of Mercury).
I tried well over a dozen times to seal my gas tank caps. I finally
found that tightening the caps and wrapping them in a sheet of plastic
wrap sealed them well enough for a few days of pressure testing. I
turned my air compressor down to a trickle and used it to pressure the
tank and then capped off the vent outlet. It was useful to have the to
surface of the tank horizontal so that soapy water could stand in the
cap and show bubbles if it leaked. The caps are tightened by loosening
the nut on the bottom and then clockwise rotating the top and bottom cap
portions. I also put Vaseline on the O-rings.
Leland
Awaiting an O320 from Van's
Message 2
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--> RV9-List message posted by: Leland <Federigo@pacbell.net>
Both Steve Sampson and I find that our top and bottom cowls do not fit
well in the front. Here is a link from an RV7 builder that shows the
same problem.
http://our-rv7a.com/finishing_kit/finishing_kit101603.htm
I had to sand my cowl down with 80 grit paper until there were holes in
the fiberglass. This got the mismatch down to 1/16". Now I will
reinforce the backside of the cowling with more glass.
Leland
Message 3
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| Subject: | Re: Bare Aluminum Cleaner |
--> RV9-List message posted by: "Jen Coull" <cfiijen@hotmail.com>
Maybe I should clarify some things....
I was recommending the best way to clean off the aluminum, not prep for
painting.
I prime with alodine and scuff the surface thoroughly with a red scotch
brite pad.
After that, it is cleaned well with dawn dish soap and water. Next I use the
alcohol to clean
off any last bit of fingerprints. Before alodine, the surface must be acid
etched and then
thoroughly rinsed. After this it is dunked in an alodine tank, then rinsed
and air dryed.
Since I live in Florida (salty air), several tech advisors have also suggest
an epoxy primer
on top of that. So I am using Sherwin Williams Mil-Spec Aerospace Primer.
I am applying this with an HVLP sprayer and getting great results. Lots of
work? Oh yeah.
Jen
#90349
Never get a busy signal because you are always connected with high-speed
Internet access. Click here to comparison-shop providers.
https://broadband.msn.com
Message 4
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"RV-9A @ Yahoo" <RV-9A@yahoogroups.com>
| Subject: | Gear leg pictures |
--> RV9-List message posted by: "Andy Karmy" <andy@karmy.com>
There was a query for gear leg fairing pictures...
Well here you go.
http://www.karmy.com/rv9a/pictures/fuselage/Fairings
- Andy
Message 5
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| Subject: | pneumatic squeezer tips? |
--> RV9-List message posted by: Paul Eastham <abstraction@yahoo.com>
Hi all,
I had quite an awful time with my newly-acquired (but rather old and rickety)
cp-214 pneumatic squeezer the other day. The worst of it was that I squeezed a
ring in one of my attach angles when trying to adjust the set after changing
yokes, but that was my fault and my first scream-out-loud RV error. Oh well,
I'm now a member of the build-it-again club...
But the problem I'm looking for help with is that the squeezer often "kicks" in
one direction or the other as it finishes squeezing the (AD4) rivet, leaving me
with a slightly sloped shop head. In all cases they are within the mil-spec
(i.e. .05 to .07 head thickness for an AD4) but they don't look very neat, and
when they're all suboptimal like this I start to worry.
Is this at all a problem?
Any tips to keep things straight?
I've tried eyeballing it as much as possible, making sure the shop-head-side
hits dead center on the die (which is hard), and holding the manufactured-side
of the yoke down as much as possible. These help a little but the results are
not as good as I would like.
Thanks for any advice!
Paul
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