Gary Leinberger,
Sorry that I have overlooked your questions amongst the great number of
comments following my message to the list.
My tank was delivered in 2000 and there has been fuel in it since August
2005.
Then some comments to your eventual aluminium tank.
I have maid some design calculations for a new TIG welded tank made of
aluminium which is 70 mm higher than the original. With a stiffener
spacing of 135 mm and 250 mm, the minimum thickness required for an
internal pressure of 3.5 psi (FAR 23) using a 5052 quality came out at
1.74 mm. So I will use 2 mm. At the present stage the horizontal
stiffeners on the forward and aft walls are corrugations and the
vertical stiffeners are 3 longitudinal bulkheads. The weight is
calculated to 11.3 kilogram. I learned last night that Graham had used
magnesium in his tank weighing 7.8 kilogram. I think the density of
magnesium is around 1.7 compared to 2.7 for aluminium. I have some
experience applying aluminium in high speed crafts, but no experience
with magnesium. So I think I will pay the weight penalty and stick to
aluminium. The volume with a simplified geometry in the lower part is 83
litres. As soon as I obtain more information about the space available
in that area, I intend to increase the volume somewhat.
Regards
Arnold
-----Opprinnelig melding-----
Fra: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] P=E5 vegne av Gary
Leinberger
Sendt: 29. april 2008 22:58
Til: europa-list@matronics.com
Emne: RE: Europa-List: Fuel tank - bulges and leakage.
How old is your tank and how long have you had fuel in it? I had to
replace mine - it was my fault in the sense that I pressure tested it
with too much air pressure and ended up with stress cracks on the outer
edges where the wing comes in - but the real problem seems to be it is
not a very flexible material and over time I am afraid I will need to
replace it again - if I do I guess I will get an aluminium tank welded
up - pictures of land Rovers running over the tank may not be the best
approach to judging the long term ability of the tank to accept stress -
Gary Leinberger
A237
_____
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Arnold Kr.
Hansen
Sent: Tuesday, April 29, 2008 1:52 PM
Subject: Europa-List: Fuel tank - bulges and leakage.
Hi,
Shortlybefore start of taxiing, it was discovered that fuel was coming
out of the fuselage on my Europa XS trigear (LN-ABM), through the access
holes below the tank. Draining of the tank was started and the leakage
stopped when 20 - 25 litres were remaining in the tank.
Two daysbefore I had drained the tank completely since the aircraft had
been stationary (in a heated hangar) since 1. july 2006 with app. 35
litres of mogas in the tank. The day of start up I filled 18 litres and
checked all hose connections. Started the engine and runned it for 5
minutes to check hose connections to the recently installed oil
thermostat. Then filled another 36 litres of mogas and started the
engine for the local flight.
Removing the wings, it was revealed that the tank front facing the wing
spars, had great bulges, bulges inwards and outwards, and the centre one
touching the aileron cross tube, see attached picture. I have not yet
localized the crack, but I suspect the saddle section just ahead of the
fibreglass bracket. To me the in and out shape of the bulges indicate
compression stresses due to material expansion (caused by the fuel
applied, 95 octane mogas?). And I think the crack is caused by shear
stresses just forward of the bracket mentioned.
I will appreciate comments and advice. At present I do not trust the
material, polyethylene, used in the tank. Has anybody applied metal
tanks?
Regards
Arnold Kr. Hansen
Europa XS trigear, Kit No.381
|