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Alternative fuel tank mounting?

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asarangan(at)gmail.com
Guest

Posted: Thu Dec 05, 2013 10:02 pm Post subject: Alternative fuel tank mounting?

I am hoping someone can comment on an alternative tank mounting

strategy. A picture of what I am thinking is attached.



To avoid any potential stresses developing due to tank expansion, I am

thinking of horizontally bracing  the fuel tank against the baggage

bay wall using two fiberglass straps all the way around the tank - one

strap below the tank ledge and the other just above the outlet bosses.

These straps are for simply maintaining the fore/aft and lateral

position of the tank. Vertically, the tank will simply sit on the

fuselage floor. The tank bottom is nearly flush with the baggage bay

floor, so it should sit nice and even on the fuselage. With this

setup, I have satisfactory clearance between the spars, pitch tube and

the tank outlets. I plan to add a thin neoprene pad around the tank

bottom to make sure there are no hard points of contact between the

tank and the fuselage. The neoprene is oil resistant, non-absorbent

and has fire resistance.



Since this is such an irreversible step, I want to make sure I am

thinking this through correctly. Probably the larger questions are,

will the fuselage floor be able to take the entire tank load? Is there

any issue with letting the top portion of the tank (the ledge)

floating with no vertical support?

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Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Thu Dec 05, 2013 10:27 pm Post subject: Alternative fuel tank mounting?

On Dec 5, 2013, at 10:01 PM, Andrew Sarangan wrote:

 	  Quote: 	
		  I am thinking of horizontally bracing  the fuel tank against the baggage

bay wall using two fiberglass straps all the way around the tank - one

strap below the tank ledge and the other just above the outlet bosses. 	




Andrew...a question:

Are you planning to bond these fiberglass straps to the fuel tank as they encircle the tank?   If so, do you have any concerns about stress concentrations building up in the tank adjacent to the straps?

Fred



 [quote][b]

asarangan(at)gmail.com
Guest

Posted: Thu Dec 05, 2013 10:37 pm Post subject: Alternative fuel tank mounting?

No, the straps will not be bonded to the tank, just to the baggage bay

wall.  The side of the strap facing the tank will have a neoprene pad,

so there will be some 'give' to accommodate small expansions.

On Fri, Dec 6, 2013 at 1:26 AM, Fred Klein <fklein(at)orcasonline.com> wrote:

 	  Quote: 	
		  

 On Dec 5, 2013, at 10:01 PM, Andrew Sarangan wrote:



 I am thinking of horizontally bracing  the fuel tank against the baggage

 bay wall using two fiberglass straps all the way around the tank - one

 strap below the tank ledge and the other just above the outlet bosses.

 Andrew...a question:



 Are you planning to bond these fiberglass straps to the fuel tank as they

 encircle the tank?   If so, do you have any concerns about stress

 concentrations building up in the tank adjacent to the straps?



 Fred

kheindl(at)msn.com
Guest

Posted: Thu Dec 05, 2013 10:43 pm Post subject: Alternative fuel tank mounting?

Hi Andrew,



I think you are going out on a limb with this idea. A full tank is a very heavy load and the fuselage floor is not designed to take this, or the designers would have placed it on the floor.

The load should be taken up entirely by the cockpit module.

Karl





 	  Quote: 	
		   From: asarangan(at)gmail.com

 Date: Fri, 6 Dec 2013 01:01:29 -0500

 Subject: Alternative fuel tank mounting?

 To: europa-list(at)matronics.com

 

 I am hoping someone can comment on an alternative tank mounting

 strategy. A picture of what I am thinking is attached.

 

 To avoid any potential stresses developing due to tank expansion, I am

 thinking of horizontally bracing  the fuel tank against the baggage

 bay wall using two fiberglass straps all the way around the tank - one

 strap below the tank ledge and the other just above the outlet bosses.

 These straps are for simply maintaining the fore/aft and lateral

 position of the tank. Vertically, the tank will simply sit on the

 fuselage floor. The tank bottom is nearly flush with the baggage bay

 floor, so it should sit nice and even on the fuselage. With this

 setup, I have satisfactory clearance between the spars, pitch tube and

 the tank outlets. I plan to add a thin neoprene pad around the tank

 bottom to make sure there are no hard points of contact between the

 tank and the fuselage. The neoprene is oil resistant, non-absorbent

 and has fire resistance.

 

 Since this is such an irreversible step, I want to make sure I am

 thinking this through correctly. Probably the larger questions are,

 will the fuselage floor be able to take the entire tank load? Is there

 any issue with letting the top portion of the tank (the ledge)

 floating with no vertical support?


	




 		 	   		  

  [quote][b]

Fred Klein

Joined: 26 Mar 2012
Posts: 503

Posted: Thu Dec 05, 2013 11:02 pm Post subject: Alternative fuel tank mounting?

On Dec 5, 2013, at 10:36 PM, Andrew Sarangan wrote:

 	  Quote: 	
		  No, the straps will not be bonded to the tank, just to the baggage bay

wall.  The side of the strap facing the tank will have a neoprene pad,

so there will be some 'give' to accommodate small expansions.

	




Andrew...if I had it to do over again, I would attempt to ensure that the underside (including the "ledge") is fully supported yet free to expand and contract...I would install all the tapes to the CM which are called for, but I would provide a cushioned bond-break between the tape and the tank. In my attached build-photo, the FG tape was regrettably bonded to the tank.

Fred



 [quote][b]

hagargs(at)earthlink.net
Guest

Posted: Fri Dec 06, 2013 4:50 am Post subject: Alternative fuel tank mounting?

Andrew;

If I were to do it over again I would form several brackets or pockets of formed fiberglass to hold the tank in place but not be bonded to the tank.  Look at the corners of the tank by the tunnel.  Brackets formed there would be very stiff because of the 90 degree angle. Forming a contour along the module at the radiused edge of the tank would give lateral support. I also thought that bonding some aluminum angle to the module where the top of the tank's ledge would rest on would be good to inhibit forward and back rocking movements. That foam as a compliant surface is right on the mark where anything touches the tank. All edges of any brackets should be radiused away from the tank so that the edge is pointed away from the tank,



Steve Hagar

A143  Mesa AZ



--

asarangan(at)gmail.com
Guest

Posted: Fri Dec 06, 2013 12:06 pm Post subject: Alternative fuel tank mounting?

Karl



Thank you for the comment. This was my concern too. However, after

staring at the canoe floor, I am not so sure if there is really any

difference.  Even with the standard installation, the majority of the

load is borne by on the baggage bay wall, which is eventually bonded

to the fuselage floor anyway. The floor where the baggage bay bonds

and the floor directly beneath the tank are on the same piece of

reinforced foam. So in terms of load, I can't see any difference

whether the tank is directly sitting on the canoe floor or if it is

supported by the baggage bay which is subsequently supported by the

canoe floor.



Also, I am also having a hard time understanding why the top ledge of

the tank requires a separate support. My measurement says there is

only about 2 gallons of fuel here, so 12 lbs is hardly worth bonding

with 6 plies of glass for its entire length.



If anyone has any insights into this, I'd love to hear.



Thank you!



On Fri, Dec 6, 2013 at 1:42 AM, Karl Heindl <kheindl(at)msn.com> wrote:

 	  Quote: 	
		   Hi Andrew,



 I think you are going out on a limb with this idea. A full tank is a very

 heavy load and the fuselage floor is not designed to take this, or the

 designers would have placed it on the floor.

 The load should be taken up entirely by the cockpit module.



 Karl



> From: asarangan(at)gmail.com

> Date: Fri, 6 Dec 2013 01:01:29 -0500

> Subject: Alternative fuel tank mounting?

> To: europa-list(at)matronics.com



>

> I am hoping someone can comment on an alternative tank mounting

> strategy. A picture of what I am thinking is attached.

>

> To avoid any potential stresses developing due to tank expansion, I am



> thinking of horizontally bracing the fuel tank against the baggage

> bay wall using two fiberglass straps all the way around the tank - one

> strap below the tank ledge and the other just above the outlet bosses.

> These straps are for simply maintaining the fore/aft and lateral

> position of the tank. Vertically, the tank will simply sit on the

> fuselage floor. The tank bottom is nearly flush with the baggage bay

> floor, so it should sit nice and even on the fuselage. With this

> setup, I have satisfactory clearance between the spars, pitch tube and

> the tank outlets. I plan to add a thin neoprene pad around the tank

> bottom to make sure there are no hard points of contact between the

> tank and the fuselage. The neoprene is oil resistant, non-absorbent

> and has fire resistance.

>

> Since this is such an irreversible step, I want to make sure I am

> thinking this through correctly. Probably the larger questions are,

> will the fuselage floor be able to take the entire tank load? Is there

> any issue with letting the top portion of the tank (the ledge)

> floating with no vertical support?

kheindl(at)msn.com
Guest

Posted: Fri Dec 06, 2013 2:45 pm Post subject: Alternative fuel tank mounting?

You are right, but with the cockpit module and baggage bay assembly the load is spread out over a much greater area. If the tank sits on the floor the actual contact area is probably quite small. Just think of the weight, and if you make a hard landing,the weight is double. Maybe there is a way to re-enforce the floor, but I would find a qualified engineer to do some calculations, preferably someone from Europa/Swift.

karl





 	  Quote: 	
		   From: asarangan(at)gmail.com

 Date: Fri, 6 Dec 2013 15:05:23 -0500

 Subject: Re: Alternative fuel tank mounting?

 To: europa-list(at)matronics.com

 

 --> Europa-List message posted by: Andrew Sarangan <asarangan(at)gmail.com>

 

 Karl

 

 Thank you for the comment. This was my concern too. However, after

 staring at the canoe floor, I am not so sure if there is really any

 difference.  Even with the standard installation, the majority of the

 load is borne by on the baggage bay wall, which is eventually bonded

 to the fuselage floor anyway. The floor where the baggage bay bonds

 and the floor directly beneath the tank are on the same piece of

 reinforced foam. So in terms of load, I can't see any difference

 whether the tank is directly sitting on the canoe floor or if it is

 supported by the baggage bay which is subsequently supported by the

 canoe floor.

 

 Also, I am also having a hard time understanding why the top ledge of

 the tank requires a separate support. My measurement says there is

 only about 2 gallons of fuel here, so 12 lbs is hardly worth bonding

 with 6 plies of glass for its entire length.

 

 If anyone has any insights into this, I'd love to hear.

 

 Thank you!

 

 

 

 

 

 On Fri, Dec 6, 2013 at 1:42 AM, Karl Heindl <kheindl(at)msn.com> wrote:

 > Hi Andrew,

 >

 > I think you are going out on a limb with this idea. A full tank is a very

 > heavy load and the fuselage floor is not designed to take this, or the

 > designers would have placed it on the floor.

 > The load should be taken up entirely by the cockpit module.

 >

 > Karl

 >

 >

 >

 >> From: asarangan(at)gmail.com

 >> Date: Fri, 6 Dec 2013 01:01:29 -0500

 >> Subject: Alternative fuel tank mounting?

 >> To: europa-list(at)matronics.com

 >

 >>

 >> I am hoping someone can comment on an alternative tank mounting

 >> strategy. A picture of what I am thinking is attached.

 >>

 >> To avoid any potential stresses developing due to tank expansion, I am

 >

 >> thinking of horizontally bracing the fuel tank against the baggage

 >> bay wall using two fiberglass straps all the way around the tank - one

 >> strap below the tank ledge and the other just above the outlet bosses.

 >> These straps are for simply maintaining the fore/aft and lateral

 >> position of the tank. Vertically, the tank will simply sit on the

 >> fuselage floor. The tank bottom is nearly flush with the baggage bay

 >> floor, so it should sit nice and even on the fuselage. With this

 >> setup, I have satisfactory clearance between the spars, pitch tube and

 >> the tank outlets. I plan to add a thin neoprene pad around the tank

 >> bottom to make sure there are no hard points of contact between the

 >> tank and the fuselage. The neoprene is oil resistant, non-absorbent

 >> and has fire resistance.

 >>

 >> Since this is such an irreversible step, I want to make sure I am

 >> thinking this through correctly. Probably the larger questions are,

 >> will the fuselage floor be able to take the entire tank load? Is there

 >> any issue with letting the top portion of the tank (the ledge)

 >> floating with no vertical ======================

&gt========
	


 	  Quote: 	
		   

 

 


	




 		 	   		  

  [quote][b]

spcialeffects

Joined: 29 Aug 2012
Posts: 306
Location: Kent

Posted: Fri Dec 06, 2013 2:58 pm Post subject: Re: Alternative fuel tank mounting?

So this is the stage that im at in my build and have been putting off bonding in the tank as so many have been reported to have split recently. Bud yearly has produced a solution fix using 1/8'' cork but the three main things i have put to the top of my list to stop my tank from having problems later on are.. firstly before bonding in the tank fill with fuel and leave in for as long as possible so that the tank expands and trust me mine grew on the back wall were the fuel comes in from the cobra by about 1/2''. Secondly bond the tank into the module when it is in this expanded state but dont bond the glass to the tank. Put some sort of release agent on the tank so that when the tank shrinks back to its original size the glass would have already set at the tanks maximum size and this then leaves the "room" for the expansion and contraction of the tank later on, and finally once the plane is up and flying dont leave the tank dry keep it at least half full. When i bond in my tank which im hoping to do next week i also want to make a cradle of it to sit in like another builder has done on the europa owners site. his photo is attached. Just my two pence worth but may be some use. Regards Frank

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budyerly(at)msn.com
Guest

Posted: Fri Dec 06, 2013 4:03 pm Post subject: Alternative fuel tank mounting?

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Fred,

 We all learned the hard way that the tank really bonds well to the  glass.  Your advise is sound.

  

 The point that the floor is not strong enough to hold the whole  tank is important!

 The method I use has a shelf that glasses the tank aft support to the floor  and the back wall.

 I do not glass the saddle but only up the sides a bit to assist in side to  side motion.

  

 The front of the tank must be supported also, but not solely by a wedge of  foam or filler, it must be a glass beam.

 Typically the tank will set 1/2 to 3/4 inch off the floor.  That area  is filled in most cases with expand cell, smoothed and then glassed over to  provide a beam support.

 Of course the forward ledge is a good support for the top of the tank as  is.

 As you all know I use a thin cork or similar (one of my clients used felt)  to allow the tank to move as it expands and contracts with fuel to try to  prevent stress risers.

 Also it is imperative that the tank be wedged in with the forward tank  supports, as well as foam on the sides, front and top to keep it  firmly in place. 

  

 Should one have followed the assembly manual (as one would think we should)  and the tank sag becomes apparent, I have filled the area between the tank and  the floor with foam to spread the load out a bit.  It is only a band-aide  and not a cure.  Someone asked if the forward wedge could be glassed to the  tank, and I don't believe that is sound as it would become another stress riser  now on the forward side.

  

 Bottom line, Do not just let the tank rest on the floor.

  

 Andrew, 

 The wrap around the tank only holds it from fore and aft movement as you  said but foam will do that also.  Something has to hold that 120 lbs of  fuel and tank at 6+ gs.  The glass aft bulkhead and T in the front will do  it, but not without a sag on that front edge.  I thought about a floor pan  under the tank and a uni strap diagonally from the top rear bulkhead to the  pan to hold the front of the tank early on, but a simple glassed beam on the  floor is all that should be necessary.  Make your forward T on the bench  and let it cure (make a mold) then Redux to the front.  On the aft  saddle and bulkhead, put a layer of thin release plastic on the tank ( I put  cork on the tank also) and make your bracket tapes per the book.  Put  the cockpit module in (I have the advantage of a ceiling hoist so it is easy for  me to say) and check the position and mark the tank outline.  Remove the  tank and make a aft bulkhead to belly support as well as a line under the front  of the tank about 2 inches wide of expand cell or similar and cover with release  plastic.  (You noticed the flexibility of the module, so a strap of glass  to hold the bulkheads vertical is fairly smart.)  Set the module in place  and allow the expand cell to cure.  Pull the module again  (repetitive isn't it) and check, fill voids and smooth in preparation for 2  layers of glass over the expand cell or filler.  Set the module in again  and once assured it is all comfy, you are ready for bonding.  In the 5  years 12AY has had its tank, it has been left full of fuel, empty, and every  sort of load between and the support I have has left the tank still looking like  new, no sags in the floor or belly and has served me well.  My tank is the  new style tank which is a bit thicker, reinforced and holds just a bit more fuel  somehow.  The top is nice and flat for a change.  Older tanks are  thinner and do bulge as many have commented on.

  

 Just my two cents.

  

 Regards,

 Bud Yerly

 [quote]   ---

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