Hi Bill
If you are serious about constructing your own alloy tank, here are some
of the issues that I considered carefully before embarking on what
turned out to be a lengthy project.
Capacity
If you want to maximise capacity, the tank shape will be complex to take
advantage of the available space. I went "full span" and put seamless
tubes through to accommodate pitch control and rudder cables. Since you
have sawed off the top of your cockpit module, there is now room to
extend the tank vertically up by about 100 mm (to the door sill), this
should give you an extra 18 litres. Restore the strength of the CM joint
using standard "good composite practice".
This should not compromise the seating or baggage-bay access.
Mounting
The tank cannot sit on the bottom of the fuselage but should be clear.
Incorporate supporting brackets to spread the (considerable) load to the
front and rear of the cockpit module (seat back). Design in some method
of allowing the tank to expand and contract - sitting it on a rubber or
cork mat for instance.
Breathing
Use considerably larger breathers than were originally fitted - to
prevent pressure build-up and blow-back while filling. If possible use
two, one on each side of the tank. I routed mine up and then down,
venting under the fuselage, to prevent siphoning or fuel dumping in the
event that the aircraft ever flipped over.
Fuel Return
I pondered the ideal configuration for the fuel return line (discussed
ad-nauseum since!) and opted to return it to the top of the tank. A
vertical cross-drilled pipe inside the tank allows the fuel to dribble
down without vapourising or having to contend with the back-pressure of
a full tank.
Fuel Level Monitoring.
There are now far more options available to accurately monitor the fuel
contents. Capacitance level sensors work well but are sensitive to fuel
type, if you only ever use one type of fuel, this won't be an issue.
They can be used with a "lookup table" to linearize the readout giving
an accurate indication of fuel contents. Float switch stacks are the
next option, (as supplied by Europa) they are reliable and not fuel
sensitive but give a non-linear indication. I opted for the former but
included four optical sensors to give an independent indication of fuel
contents at "Full", 2/3 1/3 and "Reserve" and chose to delete the
standard "stand pipe", which, without any method of isolating, I
considered a safety risk.
Maintenance
Now is a good time to include an inspection hatch. Machine a large
diameter "weld-in" ring with matching cover, tapped for at least six
bolts. Include a groove to accept a Viton "O" ring to seal the joint.
This cover also makes an ideal mount for the fuel level sender.
Good luck and keep us informed of progress.
Nigel
On 11/11/2013 22:43, bill wrote:
> Thank you Nigel,
>
> Having got the top off now I can see that the leak is at the shelf on
> the front of the tank where it sits on the mount. It appears that the
> fibreglass had bonded to the tank and with movement caused a fracture
> due to the stress. Having looked at the tank now which is very
> deformed and reducing capacity, I am sure a "metal" one will be much
> superior. Fortunately there are some very good craftsman around here
> so fabrication will not be a problem. Not sure we will get to the same
> volume as you have but will certainly look for more than I have now.
> Will send some pic,s when all done.
>
> Regards
>
> Sue and Bill Sisley
> On 12/11/2013 8:55 a.m., nigel_graham@m-tecque.co.uk wrote:
>> Hello Bill,
>>
>> I'm a bit late getting back on this one but as others have said, I
>> built a tank out of 5251 quarter-hard magnesium alloy.
>> It weighs 7850 grams and has a capacity of 110 litres.
>> I incorporated internal baffles, and breathers with proper AN
>> fittings to accommodate alloy pipework. It is also fitted with a full
>> length capacitive probe and four solid-state optical fuel level sensors.
>> http://www.europaowners.org/main.php?g2_itemId=28719
>>
>> The only advice I would offer is: allow yourself a long time to make and
>> perfect
your cardboard templates - the fuselage is partly conical in section so the
development will be an interesting shape. Choose a welder based on his ability
to weld alloy and don't fall into the trap I did of restricting yourself to
a CAA approved welder whose self-belief exceeded his ability!
>>
>> Nigel
>>
>>
>> On 08/11/2013 21:37, bill wrote:
>>>
>>> After 1100hrs I have suffered a failed fuel tank on my XS Mono. Not
>>> sure exactly where the fault is other than it is high up on the
>>> tank. Will know more when I get it out.
>>>
>>> My question to the forum is, has anyone tried fabricating a metal
>>> (aluminium) tank rather than using the Polyethylene plastic one as
>>> supplied with the kit. If so, were you able to obtain the same
>>> volume and any other advice you may be able to offer.
>>>
>>> Many thanks
>>> XS Mono
>>> Kit 456
>>> 914 and Airmaster
>>> 1100hrs
>>>
>>>
>>> Sue and Bill Sisley
>>>
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>>
>> *
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>> *
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> *
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