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tank support layups

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Rowland_Carson

Joined: 04 Jul 2008
Posts: 155
Location: Cheltenham, England

Posted: Fri Feb 20, 2009 4:34 pm Post subject: tank support layups

Done it again - come up against a query on a Friday after the factory 

tech help has gone off for the weekend!



I'm trying to set up the tank for the T-shaped support layups.



(1) the tunnel in the tank and the one in the cockpit module baggage 

area differ in level by about 30mm; the manual shows them 

more-or-less level with a layup sailing across. Also, the profiles of 

the tunnel are quite different on the tank and CM which makes the 

step bigger in places. I've put in the recommended 20mm spacer 

between the headrest area and the tank, and the bottom of the tank is 

almost flush with the bottom of the cockpit module, so things are 

correctly aligned there. Have I positioned something wrong, or is it 

OK to have a 30mm joggle in the layup?



(2) how have people done the parts of the number 2 & number 3 layups 

that go between the tank and the CM? Seems they would need to be put 

in position with the tank slightly displaced from its correct 

position to allow room to work, but shifting the tank around doesn't 

seem a good idea if the number 1 layup at the front of the tank is 

already done.



Any ideas?



regards



Rowland

-- 

| Rowland Carson  LAA #16532    http://home.clara.net/rowil/aviation/

| 1190 hours building Europa #435 G-ROWI  e-mail <rowil(at)clara.net>

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craigb(at)onthenet.com.au
Guest

Posted: Fri Feb 20, 2009 5:17 pm Post subject: tank support layups

Yes mine was the same in the tunnel area, some areas being about 30mm out. I

just blended it out

as best as possible. I put a small amount of flox in these areas to help

with the radius. As for the T layups

I just spread the gap slightly by reducing the packing under one end of the

CM to allow access into the area

for the layup, then replaced the packing to close the gap again. hope this

is some help



craig



--

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Rowland_Carson

Joined: 04 Jul 2008
Posts: 155
Location: Cheltenham, England

Posted: Sat Feb 21, 2009 6:48 am Post subject: tank support layups

At 2009-02-21 08:59 +0000 Robert C Harrison wrote:



 	  Quote: 	
		  I recall that the tank needs to be as high as possible ( when

viewed with the assembly in the "flying mode") This is to ensure that

the wing spars do not conflict with the ledge of tank which runs across

the width of the a/c.


	


Bob - thanks for that reminder. I think I can check it without 

actually going to the bother of re-rigging the wings to the cockpit 

module



 	  Quote: 	
		  I don't understand your statement " flush with the bottom of the cockpit

module"?  Do you mean "bottom" to mean the area which sits on the floor

of the fuselage


	


Yes, I meant the part that will at the bottom when everything is right way up.



 	  Quote: 	
		  the radius of

the tank bottom does NOT sit on the fuselage it sits on more lay ups

between it and the fuselage bottom


	


I don't see any references in the manual to any layups under the tank 

(when it is right-way-up) apart from the t-section ones I've 

mentioned. The drawing in the manual shows the bottom of the tank 

fairly much in line with the bottom of the baggage bay and seat parts 

of the cockpit module.



regards



Rowland

-- 

| Rowland Carson  LAA #16532    http://home.clara.net/rowil/aviation/

| 1190 hours building Europa #435 G-ROWI  e-mail <rowil(at)clara.net>

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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gregoryf.flyboy(at)comcas
Guest

Posted: Mon Feb 23, 2009 10:50 pm Post subject: tank support layups

Hi Rowland,



I would suggest (if you haven't already) making sure to soak the tank with

fuel for awhile, before fitting and glassing it, since it will expand

slightly. Otherwise, the tank would swell and create pressure points, and

small clearances might change. I should have the fluorinated tank (circa

Nov, 2001), but how can one know 100%? I believe the fluorinated tank will

swell slightly, anyway. After having the tank swell with fuel for a few

months (while doing other things, I don't think it needs to be that long),

it was apparent that the large flat, unsupported, rear faces of the tank

wanted to bulge outward, due to the weight of the fuel. Thus, once

installed, the tank will probably have a tendancy to want to push forward in

the module, but hopefully the spacers will tame it, and keep it at bay. Just

before installing the tank, I had to heat the rear tank faces and clamp them

down with a sheet of plywood and 2x4's on both sides, to get it to want to

revert back to its proper form, and allow proper tank placement in the

module, for glassing. 



Upon draining the fuel, I had the tank glassed in within a day or two, to

stay ahead of the shrinkage curve.



The two most important alignment points (top and bottom, not side to side)

were the clearance of the wing spars at the top of the tank, and the fuel

outlets touching up against the pitch tube at the bottom of the tank.



I simply got the shelf of the tank to go as high as it would go in the

module (or as low as it would go, if the module is upside down), and then

tipped the tank to clear the tank outlets touching on the pitch tube, and

allow a little extra for the rubber hose. It seemed to work well. My tank

sits slightly tipped.



Once the fuel remnants dried out of the walls, the tank outlets (with the

rubber and clamps installed) were rubbing up against the pitch tube, just

slightly, especially when cold.  I am confident that the addition of fuel

will regain the proper clearance. There is at least 3-4mm (guessing) of dead

air space between the very bottom brackets and the tank (not the saddle

plies, but next to the fuselage bottom, where the brackets hold the tank up

off the floor of the fuselage), due to tank shrinkage. That should

approximate the extra clearance regained between the tank outlets and the

pitch tube, when the fuel is put back in the tank. In the meantime, I placed

a tie wrap on the rubber and clamp, so that the pitch tube would wear on it,

instead of the rubber/clamp (it was mostly centered on the metal clamp).



Nowhere, did I allow the plies to stick to the tank (using benefits of

others experiences). This was done by placing plastic or plastic tape

wherever the plies contacted the tank. 

This should cure the dreaded tank crack in the saddle area, that others have

experienced, especially when draining the tank for extended periods.

It will also allow for easy tank replacement later. There are measurements

in my journal as to where to cut the top of the module, to allow clearance

to pull the old tank straight up and out.



Also, on the tough, first bracket for the shelf of the tank (top side), I

make an aluminum spring to hold it to the module. It is simply a piece of

aluminum about 1 inch wide (which I covered in saran wrap) that is curved

into an arc. A hole was placed on either side of the spring, and the arc

part faced the ply, and the sides of the spring were pressed down to the

module, where the small screws held the spring in place. This held the ply

flat against the module, across its entire length, and made that part of the

job real easy. For grins and assurance to keep the ply from moving, I also

peeled back the ply (which still had its plastic backing to keep the glass

from bending out of shape), right before putting on the spring, and dabbed

small amounts of 4-minute epoxy on the module side of the bracket. That

toughest-to-do ply was the straightest and neatest one of all the plies on

the gas tank. Too bad it is the one that is the least visible  .



Regards,

Greg Fuchs, A050

Tigard, OR



P.S. I am sorry about your loss, recently. 






At 2009-02-21 08:59 +0000 Robert C Harrison wrote:



 	  Quote: 	
		  I recall that the tank needs to be as high as possible ( when

viewed with the assembly in the "flying mode") This is to ensure that

the wing spars do not conflict with the ledge of tank which runs across

the width of the a/c.


	


Bob - thanks for that reminder. I think I can check it without 

actually going to the bother of re-rigging the wings to the cockpit 

module



 	  Quote: 	
		  I don't understand your statement " flush with the bottom of the cockpit

module"?  Do you mean "bottom" to mean the area which sits on the floor

of the fuselage


	


Yes, I meant the part that will at the bottom when everything is right way

up.



 	  Quote: 	
		  the radius of

the tank bottom does NOT sit on the fuselage it sits on more lay ups

between it and the fuselage bottom


	


I don't see any references in the manual to any layups under the tank 

(when it is right-way-up) apart from the t-section ones I've 

mentioned. The drawing in the manual shows the bottom of the tank 

fairly much in line with the bottom of the baggage bay and seat parts 

of the cockpit module.



regards



Rowland

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Rowland_Carson

Joined: 04 Jul 2008
Posts: 155
Location: Cheltenham, England

Posted: Tue Feb 24, 2009 9:52 am Post subject: tank support layups

At 2009-02-23 22:46 -0800 Greg Fuchs  wrote:



 	  Quote: 	
		  I would suggest (if you haven't already) making sure to soak the tank with

fuel for awhile, before fitting and glassing it, since it will expand

slightly


	


Greg - I thought the gassing process was supposed to prevent this. 

Certainly the new tank I have has been subject to that process.



In my conversation with Roger at the factory yesterday about several 

aspects of tank mounting he was careful to mention that one 

side-effect of the treatment is to make the epoxy more likely to 

stick to the tank. He recommended a layer of polyethylene or similar 

film between tank and layup to allow relative movement. However, he 

didn't suggest soaking the tank with fuel beforehand.



Looks like another call to check could be worthwhile.



Thanks for all your tips about where interference between tank and 

other structures might arise.



 	  Quote: 	
		  I am sorry about your loss


	


Thanks for your kind words. It's a big change being without someone 

who's shared your life for 40 years, and even worse (for the 

survivor) when it comes rather suddenly. The period of adjustment 

appears open-ended at present. As well as getting back to aeroplane 

work, I am thinking about how Wilma's paintings might be published, 

as inspiration to others who might be on the same spiritual journey.



regards



Rowland

-- 

| Rowland Carson  LAA #16532    http://home.clara.net/rowil/aviation/

| 1190 hours building Europa #435 G-ROWI  e-mail <rowil(at)clara.net>

- The Matronics Europa-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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gregoryf.flyboy(at)comcas
Guest

Posted: Tue Feb 24, 2009 4:18 pm Post subject: tank support layups

Rowland,



 	  Quote: 	
		  Greg - I thought the gassing process was supposed to prevent this. 

Certainly the new tank I have has been subject to that process.


	


My tank only swelled a few millimeters (on the back face of the tank).

If the swelling is constant over the entire surface of the tank, then the

long straight faces would give the worst-case example of tank expansion.

Hence the back face of the tank is the extreme example. I wish I knew how

much the old tanks expanded, then it would be easier to know for sure.

(If anyone has measured their tank expansion who had the old tank, feel free

to contribute).



I can only assume that I have the new tank, since a few millimeters is not

much. Some might consider it negligible. Still (if I DO in fact have the new

tank) a few extra millimeters of clearance to the controls will be

necessary, if you don't soak the tank, initially. Actually (based on my

experience), if allowances are given, and the tank is not bonded directly,

you would probably be fine without pre-soaking the tank. I will try to

measure it today, to see if I can get a better idea on the amount of

shrinkage.



 	  Quote: 	
		  Thanks for your kind words. It's a big change being without someone 

who's shared your life for 40 years, and even worse (for the 

survivor) when it comes rather suddenly. The period of adjustment 

appears open-ended at present.


	


My thoughts are with you. I don't have much experience in this area. My

'separation' experience has to do with that ugly divorce word, and that was

very tough on me too, but no passing away was involved.

The memories stay, and the acute emotional pain does diminish, and the

sunlight shining through the clouds can be seen again, eventually.



Greg

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