Today's Message Index:
----------------------
1. 09:06 AM - Re: Can we borrow your tank? (William Daniell)
2. 10:13 AM - Re: venting cooling system 912S (graeme bird)
3. 11:33 PM - Re: Can we borrow your tank? (Steven Pitt)
Message 1
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| Subject: | Can we borrow your tank? |
Bud
Can you give an overview of the tank replacement surgery.
My tank has been sitting around empty during my (glacial-paced) build and
has been glassed in per the manual since 2008 and not per your post.
I am wondering whether it would be wise to bite the bullet and change the
tank before putting the top on.
What do you suggest?
Yours
Will
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Bud Yerly
Sent: 25 September, 2011 10:45
Subject: Re: Europa-List: Can we borrow your tank?
To all fuel tank concerns
Europa has 25 tanks on order, however, the mold was damaged / discarded by
the manufacturer. The new tank, made by Roger and John that I have from
2009, holds a bit more fuel (I have 20 gallons useable in my trigear filled
to the brim) and has reinforcements in addition to the normal support tabs.
I am not privy to the new tank manufacturers mold to see that it is exactly
the same. Karen expects delivery in a couple weeks, but it will have to
undergo QC first. I am watching and waiting for a tank also for a new
customer.
For those attempting to build a fiberglass composite tank using the old tank
as a mold, I believe the molding in place to be more time consuming than
just pulling the old tank and replacing it with the new tank and properly
supporting it.
Fiberglass tanks, as pointed out by Graham, have problems with auto fuel.
No fiberglass tank (epoxy, vinylester, or polyester) holds up with Auto Fuel
with Ethanol. The marine industry coats the inside of fiberglass tanks with
specialized coatings to protect the fiberglass from auto fuel additives and
ethanol. It appears AV Gas is safe with all fiberglass tanks. However, the
AV Gas formula is under review by the FAA for changes, so no guarantees.
Repairs to the current tank is difficult. Epoxy and glass stick very well
to the PTFE tank material. Jeff Roberts has successfully repaired his tank,
but it depends where your crack is. I have repaired the top of the tank
with glass and pro seal. Note, that proseal softens with time when exposed
to ethanol, but has not failed so far. The problem with glass repairs to
the tank, in my opinion, is that the bond has less peel strength than ideal
and under flexing and pressure will eventually fail.
I believe, and have put my money where my mouth is, that the solution to the
tank cracking is the support structure used for the tank.
For those of you who haven't seen my previous posts, I have attached one of
my drawings to show what I mean. The front of the tank is totally
unsupported from the area above the spars (the ledge) to the bottom rear of
the tank. Tank flexing of the older and thinner tank will force the tank to
eventually crack at the areas that are glassed hard and not allowed to move.
Whether the tank gets brittle with age, from the fiberglass interface, gets
brittle with being left empty during long repairs, or what, I really don't
care, as all poly tanks will flex, and going from empty to full will cause a
flex of a tank and eventually, if forced back and forth, will fail.
Metal cracks also unless properly supported, has condensation problems , and
it is expensive for odd shaped tanks to build, fiberglass has its fuel
compatibility problems, molding issues, etc., and PTFE or poly tanks have
their long term problems unless properly supported.
What has my company done?
Defined how to support the tank. We do not glass the tank directly to the
cockpit module structure per the instruction manual. We put release plastic
between the required build manual supports and tank to prevent the required
supports from sticking permanently and creating a stress riser. We use
glass tabs to secure it at the top, for fore/aft and side to side movement.
Polyurethane foam is used to secure the tank from shifting, and we carefully
build lower tank supports. (On a new build it means fitting the module a
couple more times to fit an expand cell pad laid along the bottom of the
tank perimeter covered with 2 mil plastic to define where the tank sits and
requires support. The expand cell is then sanded to final shape and glassed
over making a very good support.) The tank also sits on a cork support for
padding (kind of overkill) to prevent wear, but plastic works OK also. This
means the tank is supported vertically and horizontally by the saddle, the
bottom, the front ledge, and foam wedged with urethane foam to prevent
movement fore, aft , up , or down. All weight is carried by a combination
of the floor and the bulkheads.
Existing tanks have added non expanding polyurethane foam sprayed under the
tank to support the bottom, but this is not ideal as I prefer a longeron and
ribs be glassed to the floor for the tunnel area and across the front of the
tank for vertical support. This adds support for the tank bottom, back and
sides as opposed to the previous supports which hung the tank solely off the
bulkheads...
Other bandaids:
We have a plastic welder and have tried it recently on PTFE tanks used in
commercial lawn equipment (which are poorly supported fuel tanks and prone
to cracking with age) and have had success so far. Not an exact science but
we have also done an auto radiator, and a auto overflow coolant tank to see
what the long term effects are. We are concerned that the heat stress near
the weld may be brittle and fail, so time will tell. Pulling the tank and
welding is not cost effective as one may as well drop in another tank.
In the mean time, I am waiting for a new tank to drop in as that is the
easiest of all solutions, as the tank supports can be put in quite easily
through the hole in the top of the module. This I believe will solve the
problems of stress risers and tank failures. Anyone can replace a tank in
less than a week.
Regards,
Bud
Message 2
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| Subject: | Re: venting cooling system 912S |
Graham, I have XS FWFD, and the rad is under the engine, and filler pot on top,
so presumably I dont need to worry?
--------
Graeme Bird
G-UMPY
Mono Classic/XS FWFD 912ULS/Warp drive FP
Build nearing completion
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=353250#353250
Message 3
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| Subject: | Re: Can we borrow your tank? |
Will,
Bud's article will be in this months Europa Flyer due to be posted this
week.
Steve Pitt
----- Original Message -----
From: William Daniell
To: europa-list@matronics.com
Sent: Monday, September 26, 2011 5:02 PM
Subject: RE: Europa-List: Can we borrow your tank?
Bud
Can you give an overview of the tank replacement surgery.
My tank has been sitting around empty during my (glacial-paced) build
and has been glassed in per the manual since 2008 and not per your post.
I am wondering whether it would be wise to bite the bullet and change
the tank before putting the top on.
What do you suggest?
Yours
Will
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Bud Yerly
Sent: 25 September, 2011 10:45
To: europa-list@matronics.com
Subject: Re: Europa-List: Can we borrow your tank?
To all fuel tank concerns
Europa has 25 tanks on order, however, the mold was damaged /
discarded by the manufacturer. The new tank, made by Roger and John
that I have from 2009, holds a bit more fuel (I have 20 gallons useable
in my trigear filled to the brim) and has reinforcements in addition to
the normal support tabs. I am not privy to the new tank manufacturers
mold to see that it is exactly the same. Karen expects delivery in a
couple weeks, but it will have to undergo QC first. I am watching and
waiting for a tank also for a new customer.
For those attempting to build a fiberglass composite tank using the
old tank as a mold, I believe the molding in place to be more time
consuming than just pulling the old tank and replacing it with the new
tank and properly supporting it.
Fiberglass tanks, as pointed out by Graham, have problems with auto
fuel.
No fiberglass tank (epoxy, vinylester, or polyester) holds up with
Auto Fuel with Ethanol. The marine industry coats the inside of
fiberglass tanks with specialized coatings to protect the fiberglass
from auto fuel additives and ethanol. It appears AV Gas is safe with
all fiberglass tanks. However, the AV Gas formula is under review by
the FAA for changes, so no guarantees.
Repairs to the current tank is difficult. Epoxy and glass stick very
well to the PTFE tank material. Jeff Roberts has successfully repaired
his tank, but it depends where your crack is. I have repaired the top
of the tank with glass and pro seal. Note, that proseal softens with
time when exposed to ethanol, but has not failed so far. The problem
with glass repairs to the tank, in my opinion, is that the bond has less
peel strength than ideal and under flexing and pressure will eventually
fail.
I believe, and have put my money where my mouth is, that the solution
to the tank cracking is the support structure used for the tank.
For those of you who haven't seen my previous posts, I have attached
one of my drawings to show what I mean. The front of the tank is
totally unsupported from the area above the spars (the ledge) to the
bottom rear of the tank. Tank flexing of the older and thinner tank
will force the tank to eventually crack at the areas that are glassed
hard and not allowed to move. Whether the tank gets brittle with age,
from the fiberglass interface, gets brittle with being left empty during
long repairs, or what, I really don't care, as all poly tanks will flex,
and going from empty to full will cause a flex of a tank and eventually,
if forced back and forth, will fail.
Metal cracks also unless properly supported, has condensation problems
, and it is expensive for odd shaped tanks to build, fiberglass has its
fuel compatibility problems, molding issues, etc., and PTFE or poly
tanks have their long term problems unless properly supported.
What has my company done?
Defined how to support the tank. We do not glass the tank directly to
the cockpit module structure per the instruction manual. We put release
plastic between the required build manual supports and tank to prevent
the required supports from sticking permanently and creating a stress
riser. We use glass tabs to secure it at the top, for fore/aft and side
to side movement. Polyurethane foam is used to secure the tank from
shifting, and we carefully build lower tank supports. (On a new build
it means fitting the module a couple more times to fit an expand cell
pad laid along the bottom of the tank perimeter covered with 2 mil
plastic to define where the tank sits and requires support. The expand
cell is then sanded to final shape and glassed over making a very good
support.) The tank also sits on a cork support for padding (kind of
overkill) to prevent wear, but plastic works OK also. This means the
tank is supported vertically and horizontally by the saddle, the bottom,
the front ledge, and foam wedged with urethane foam to prevent movement
fore, aft , up , or down. All weight is carried by a combination of the
floor and the bulkheads.
Existing tanks have added non expanding polyurethane foam sprayed
under the tank to support the bottom, but this is not ideal as I prefer
a longeron and ribs be glassed to the floor for the tunnel area and
across the front of the tank for vertical support. This adds support
for the tank bottom, back and sides as opposed to the previous supports
which hung the tank solely off the bulkheads...
Other bandaids:
We have a plastic welder and have tried it recently on PTFE tanks used
in commercial lawn equipment (which are poorly supported fuel tanks and
prone to cracking with age) and have had success so far. Not an exact
science but we have also done an auto radiator, and a auto overflow
coolant tank to see what the long term effects are. We are concerned
that the heat stress near the weld may be brittle and fail, so time will
tell. Pulling the tank and welding is not cost effective as one may as
well drop in another tank.
In the mean time, I am waiting for a new tank to drop in as that is
the easiest of all solutions, as the tank supports can be put in quite
easily through the hole in the top of the module. This I believe will
solve the problems of stress risers and tank failures. Anyone can
replace a tank in less than a week.
Regards,
Bud
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