Fuel tank foam

Is there anyone out there using fuel tanks filled with open cell foam? I've
heard that explosions are tamed as well as fuel slosh. I've also heard that
the foam must be replaced periodically. How often is the replacement
necessary? I'm using 100LL Av gas.

--
Stuart & Kathryn Fields, Publishers
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell
(760) 608-1299 technical cell
www.experimentalhelo.com
www.vkss.com

In article ,
"Stuart & Kathryn Fields" wrote:

Is there anyone out there using fuel tanks filled with open cell foam? I've
heard that explosions are tamed as well as fuel slosh. I've also heard that
the foam must be replaced periodically. How often is the replacement
necessary? I'm using 100LL Av gas.

Most of the foam is polyurethane foam, which decomposes after exposure
to water vapor. It is not an instantaneous process, occurring over
several years, but the decomposition product is a black powder, which
can clog fuel filters, injectors, etc.

It is good for race cars, which have a limited useful life, but may
impose problems in aircraft, which operate for years.

Stuart & Kathryn Fields wrote:
Is there anyone out there using fuel tanks filled with open cell foam? I've
heard that explosions are tamed as well as fuel slosh. I've also heard that
the foam must be replaced periodically. How often is the replacement
necessary? I'm using 100LL Av gas.

Fuel cells (bladders with foam) are pretty common in the auto racing
industry. They real purpose of it is to avoid the fuel from spraying
out if the tank is ruptured. Other than that I'm not sure what
"explosion" resistance you're going to get. I suppose it might
mitigate some sloshing. I'd make sure that I was getting the
max flow rate for takeoff if I were to use one in an aircraft.

The big drawback is that they drastically decrease the fuel
carried per unit volume.

"Ron Natalie" wrote

I'd make sure that I was getting the
max flow rate for takeoff if I were to use one in an aircraft.

That should not be a problem, considering the run NASCAR engines with it,
putting out 750+ HP, at constant wide open throttle, for lap after lap, at
some tracks. Our biggest engines putting out around 300 HP would not drawn
nearly as much.

It seems to me that if you were willing to overlook the weight, the extra
volume to carry the same amount of fuel, and the extra $$$, the fact that
they can wear out and plug up your fuel system is a show stopper.
--
Jim in NC

Morgans wrote:
"Ron Natalie" wrote

I'd make sure that I was getting the
max flow rate for takeoff if I were to use one in an aircraft.

That should not be a problem, considering the run NASCAR engines with it,
putting out 750+ HP, at constant wide open throttle, for lap after lap, at
some tracks. Our biggest engines putting out around 300 HP would not drawn
nearly as much.

It IS a problem. It's a problem for NASCAR, they just engineer around
it. As I said, make sure you are designing your fuel cell for the
max flow rate (typically takeoff) and not for the cruise power
settings.

"Ron Natalie" wrote

It IS a problem. It's a problem for NASCAR, they just engineer around it.
As I said, make sure you are designing your fuel cell for the
max flow rate (typically takeoff) and not for the cruise power
settings.

What do you mean by they "engineer around it?"

The fuel cell, in the end, needs to supply the required fuel flow to make
the HP, right?

I am interested in what you have heard. I never heard about fuel cell flow
being a problem.
--
Jim in NC

Morgans wrote:
"Ron Natalie" wrote


It IS a problem. It's a problem for NASCAR, they just engineer around it.
As I said, make sure you are designing your fuel cell for the
max flow rate (typically takeoff) and not for the cruise power
settings.


What do you mean by they "engineer around it?"

The fuel cell, in the end, needs to supply the required fuel flow to make
the HP, right?

I am interested in what you have heard. I never heard about fuel cell flow
being a problem.

For those not familiar with fuel tank foam and the typical racing
application. I have run a number of SCCA race cars over the years from
Formula Fords to Trans Am, and they all must have a Fuel Cell that is an
~0.06" thick Aluminum Box to protect the Bladder and filled with foam.

The foam is a very open structure where each interconnected "bubble" is
approximately 0.10" in diameter and thus is mostly air. Another poster
mentioned 3% which sounds about right for the density. It is not so
closed as to restrict the flow of fuel in the tank but in case of a
breach in the bladder it will reduce the spray.

In order to get the necessary fuel flow it is only necessary to get the
correct pick up and size of fuel line, really no different than a
"normal" aircraft. Back in the day, circa 1987, the 700+ Hp Trans Am
cars got 4 miles to the gallon on Dash 6 Aeroquip line so unless you
have an extremely high strung motor to feed the fuel cell should be able
to handle the flow.


Mike Butler
Crew Chief
Team Traditional Slate Racing
#10 Formula Atlantic

and student pilot...

Richard: I agree the deterioration of the foam is a show stopper for me.
thanks

--
Stuart & Kathryn Fields, Publishers
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell
(760) 608-1299 technical cell
www.experimentalhelo.com
www.vkss.com


"Richard Riley" wrote in message
...
On Mon, 25 Jun 2007 07:35:36 -0400, Ron Natalie
wrote:

Stuart & Kathryn Fields wrote:
Is there anyone out there using fuel tanks filled with open cell foam?
I've
heard that explosions are tamed as well as fuel slosh. I've also heard
that
the foam must be replaced periodically. How often is the replacement
necessary? I'm using 100LL Av gas.

Fuel cells (bladders with foam) are pretty common in the auto racing
industry. They real purpose of it is to avoid the fuel from spraying
out if the tank is ruptured. Other than that I'm not sure what
"explosion" resistance you're going to get. I suppose it might
mitigate some sloshing. I'd make sure that I was getting the
max flow rate for takeoff if I were to use one in an aircraft.

The big drawback is that they drastically decrease the fuel
carried per unit volume.

I looked at the foam a few years ago. Google Reticulated Polyurethane
Foam Fuel Explosion and you'll find a few technical papers.

You take about a 3% hit on fuel volume, and you increase empty weight
by about the same. It does break down over time - the racing bladders
are only rated for 5 years. The breakdown occurs MUCH more rapidly in
the presence of an oxygenating fuel like ethanol.

I decided against it, I can't open up my tanks every few years to
replace it.

"Stuart & Kathryn Fields" wrote in
...
Is there anyone out there using fuel tanks filled with open cell foam?
I've heard that explosions are tamed as well as fuel slosh. I've also
heard that the foam must be replaced periodically. How often is the
replacement necessary? I'm using 100LL Av gas.

--
Stuart & Kathryn Fields, Publishers
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell
(760) 608-1299 technical cell
www.experimentalhelo.com
www.vkss.com




Aero Tec Laboratories Inc
http://www.atlinc.com/US/racing.html

http://www.atlinc.com/US/catalogs.html
Some ATL Fuel Cells catalogs.

http://www.atlinc.com/US/faqs_racing.html
Here's some answers concerning the foam replacement etc.

JP

JP: Thanks for the links. I've learned enough to avoid fuel tank foams.
When the engine suddenly gets quiet in my helicopter, my suds level gets
pretty high.
Thanks again.

--
Stuart & Kathryn Fields, Publishers
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell
(760) 608-1299 technical cell
www.experimentalhelo.com
www.vkss.com


"JP" wrote in message
...

"Stuart & Kathryn Fields" wrote in
...
Is there anyone out there using fuel tanks filled with open cell foam?
I've heard that explosions are tamed as well as fuel slosh. I've also
heard that the foam must be replaced periodically. How often is the
replacement necessary? I'm using 100LL Av gas.

--
Stuart & Kathryn Fields, Publishers
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell
(760) 608-1299 technical cell
www.experimentalhelo.com
www.vkss.com




Aero Tec Laboratories Inc
http://www.atlinc.com/US/racing.html

http://www.atlinc.com/US/catalogs.html
Some ATL Fuel Cells catalogs.

http://www.atlinc.com/US/faqs_racing.html
Here's some answers concerning the foam replacement etc.

JP