FWF-Insulation glue !

[rzbill]

Originally Posted by DanH

Tonny,

Bill,
<<This decision was made after seeing the results of an RV-4 in-flight fuel fire. No injuries but the aluminum skin under the rudder pedals was GONE. >>

By chance did you get any pictures? Second or third time I've heard about melting a belly skin just aft of the cowl exit. I installed a stainless exhaust ramp on my -8.

Hi Dan,
Sorry for the late reply. I lost touch with this thread until it popped back up recenty. I did not get pictures of the RV-4, however the damage was exactly how it would be expected. The root cause was a fuel leak at the fuel pressure sensor tap into the mechanical fuel pump. I was told by a common aquaintance that the pilot delayed turning off fuel, so the fire burned longer than it had to. My understanding is the fire was discovered while the aircraft was decending for a VFR pattern entry and the damage occured in the time it took to get on the ground. I want to be clear that I am not placing blame. I was not in the cockpit, he was, so I cannot say that I would do any different in regards to fuel valve. The SS firewall remained intact. The "floorboards" by the left rudder pedal (the fuel fire was mostly on the left) were burned through. Please don't hold me to this, but my weak memory says that there was about a 2" by 6" open gap in the aluminum floor and the pilot had reported his left shoe was scorched.

I like the McMaster Carr ceramic that has been found and tested on this thread. Unless there is some revelation when and if Fiberfrax is tested, I will use the McMaster stuff for a minimum 12" band from the firewall.

[DanH]

Noah, I got your PM. Last evening's post was a quick response; I had just returned from a pilots-'n-wives social event involving a nice bottle of Glenlivet <g>

Industrial samples often include boilerplate restrictions, in this case "...you agree that you will not disclose the material, or information relating to the material for any purpose to any third party..." It may be boilerplate, but it is still an agreement under which I accepted certain materials. So, I'll put it this way: If you encase Pyrogel XTF or Pyrogel 6671 in aluminum foil and place it against the backside of a red hot firewall, I don't think it will kill you, unlike some other choices. That is the focus of this thread. Careful readers of the manufacturer's published data sheet will note the products are rated for 1200F, not 2000F; the above is an off-sheet application well beyond the manufacturer's representations. They will also realize the commercial Pyrogel insulation line is not the amazing translucent blue stuff shown in the Aerogel marketing materials and used for the Stardust catcher.

Gentlemen, testing firewall insulation is a friggin' minefield; this world is full of lawyers. I originally had no intention of discussing private experiments. However, I'm also a long-time TC and my Mom sent me to school with the nuns so they could beat a conscience into her little boy. I couldn't remain silent about glue on a firewall given knowledge I already had....so here we are. Ya'll are giving me reason to think about the situation Henceforth, here's the deal.

(1) If a fellow amateur builder sends me something to test, I don't think I have any restriction about publishing my amateur results and personal opinion.

(2) If I've already tested it under another agreement, I maintain that agreement.

(3) Testing costs time and money, and I'm a volunteer. If I feel pushed, it's over.

[Noah]

Originally Posted by DanH

I had just returned from a pilots-'n-wives social event involving a nice bottle of Glenlivet <g>

Nice!

Originally Posted by DanH

Industrial samples often include boilerplate restrictions, in this case "...you agree that you will not disclose the material, or information relating to the material for any purpose to any third party..." It may be boilerplate, but it is still an agreement under which I accepted certain materials.

OK, That makes sense. I would do the same.

Originally Posted by DanH

So, I'll put it this way: If you encase Pyrogel XTF or Pyrogel 6671 in aluminum foil and place it against the backside of a red hot firewall, I don't think it will kill you, unlike some other choices. That is the focus of this thread.

Good to know.

Originally Posted by DanH

Careful readers of the manufacturer's published data sheet will note the products are rated for 1200F, not 2000F; the above is an off-sheet application well beyond the manufacturer's representations. They will also realize the commercial Pyrogel insulation line is not the amazing translucent blue stuff shown in the Aerogel marketing materials and used for the Stardust catcher.

Yes, this is the basis of my concern - aerogel is well characterized, but it has been unclear whether using small pieces of it in a fiberglass mat provides any real benefit, maybe it is just "sexy marketing". And yes, because of this thread and the realization that the published (FAA) requirement is 2000F, I became a little concerned about the 1200F mfgr's published limitation. This is certainly beyond the mfgr's published limitations. But to me, this is unimportant. It is test data that matters to me, and test data only. The fact that the data originates from a guy who is (A) a TC (B) an RV builder and (C) a professional test guy who seems to do this at his day job is all icing on the cake.

Originally Posted by DanH

Gentlemen, testing firewall insulation is a friggin' minefield; this world is full of lawyers. I originally had no intention of discussing private experiments. However, I'm also a long-time TC and my Mom sent me to school with the nuns so they could beat a conscience into her little boy.

Me too (the nuns, that is)...

Originally Posted by DanH

I couldn't remain silent about glue on a firewall given knowledge I already had....so here we are. Ya'll are giving me reason to think about the situation Henceforth, here's the deal.

(1) If a fellow amateur builder sends me something to test, I don't think I have any restriction about publishing my amateur results and personal opinion.

(2) If I've already tested it under another agreement, I maintain that agreement.

(3) Testing costs time and money, and I'm a volunteer. If I feel pushed, it's over.

Dan, that's all quite reasonable. I hope I speak for everybody interested in this thread that we appreciate your stepping up and providing invaluable test data on something that's near and dear to all of us, namely, our hides. As several have alluded to here, manufacturer's salesmanship doesn't cut it. What I was hoping for was a defacto recommendation on which product is the best choice for a homebuilder given performance, weight, and cost - but I understand your concerns about making such a blanket statement or recommendation.

Originally Posted by DanH

Given the insignificant performance difference, I don't see much point in fooling with the far more expensive product anyway.

I received my Pyrogel XT from a friend of a friend who has an in at Aspen Aerogels manufacturing facility, so it didn't cost me anything. Anybody know what the stuff costs? Nothing is available on their website.

I think I know what I need to know regarding my personal use of Pyrogel XT in my homebuilt aircraft. My offer stands to send you a sample Dan if you want to be able to publish data on it using samples obtained without restrictions. If not, no problem:! )

[DanH]

Another Sunday evening with the burner....and another surprise.

Fiberfrax has a problem.

This is about 1 minute into a session:



It only took a few minutes to determine what was happening. The flame you see here is due to the fiberfrax outgassing inside the aluminum foil envelope. Look down at the lower edge too; the soot streak is where another flame was burning merrily a few seconds before I took the picture. It has almost gone out.

This a fresh piece of plain fiberfrax exposed directly to the burner:



Note the smoke (poor photo, sun was going down and the camera flash didn't light it very well). That's binder material burning off the fiberfrax fiber mat. The binder (think of it as an adhesive) holds the fibers together. Many of you have handled fiberfrax; it has a nice firm felt-like texture with reasonable handling strength. After the burn, this sample had little handling strength in the heated area. The fibers were intact, but there was nothing to hold them together; the binder had burned away. You could poke a finger through it with ease.

Binders, adhesives, fabric sizing, and other additions to the base material are all problems when one of the goals is no smoke in the cockpit. In free air they burn away as smoke. When they outgas in an envelope they tend to ignite as they escape through a seam. Given that fiber materials really need to be encapsulated in order to be a practical cockpit-side firewall insulation (consider dirt, durability, and loose fiber), I'd have to recommend against fiberfrax inside the cabin.

[f1rocket]

Just to clarify the use of Fiberfrax on the Rutan kits, it is used only as an insulator between a thin sheet of stainless and the composite firewall core. It is not exposed directly to flame.

Great work Dan. I am following your experiments closely. I thank you for taking the time to perform these and to report the results. It is a great service to all who visit here.

[TCONROY]

Anyone try this stuff??? It's cheap.
http://www.jcwhitney.com/complete-in...lterid=c1431j1

[CharlieWaffles]

It looks like the result of this was fiberflax had a problem when encapsulted in something like foil and resulted in the gases burning when it vented. Earlier in the thread there was a test of Cerablanket from McMaster but the test was with only a stainless shield in front of it. I don't know if it was ever tested encapsulted. Does anyone know if it was?

[DanH]

Originally Posted by CharlieWaffles

It looks like the result of this was fiberflax had a problem when encapsulted in something like foil and resulted in the gases burning when it vented. Earlier in the thread there was a test of Cerablanket from McMaster but the test was with only a stainless shield in front of it. I don't know if it was ever tested encapsulted. Does anyone know if it was?

It was. No binder, so no outgas and nothing to burn inside the cabin. The only objection to Cerablanket is a possible health risk; inhaled ceramic fiber, a good reason to encapsulate in foil.

Old thread......later work showed that insulating the engine side of the firewall offers the best performance. My own airplane has no insulation inside the cabin. If I found a need (a big if) for spot insulation on the cabin side of a firewall, cerablanket in a foil envelope with no adhesive of any kind would be on the very short list of possibilities.

§ 23.1191 Firewalls.

(f) Compliance with the criteria for fireproof materials or components must be shown as follows:

(1) The flame to which the materials or components are subjected must be 2,000 ±150 °F.

(2) Sheet materials approximately 10 inches square must be subjected to the flame from a suitable burner.

(3) The flame must be large enough to maintain the required test temperature over an area approximately five inches square.

(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.

§ 23.1182 Nacelle areas behind firewalls.

Components, lines, and fittings, except those subject to the provisions of §23.1351(e), located behind the engine-compartment firewall must be constructed of such materials and located at such distances from the firewall that they will not suffer damage sufficient to endanger the airplane if a portion of the engine side of the firewall is subjected to a flame temperature of not less than 2000 °F for 15 minutes.

[Dorfie]

I am planning on using Cerablanket from Mcmaster-carr.
These are the my areas of uncertainty:
Most discussions mention Aluminum foil for encapsulating the Cerablanket. 1. For engine side of firewall installation, should one not use SS foil on the engine side rather than aluminum (which will melt rather quickly I would think)?
2. Should I use aluminum foil on the other (firewall) side as encapsulating material?
Then the last question:
As in case of the RV4 fire with melted floor, I am left with clear impression that insulating the firewall alone leaves one with the risk of burn through the aluminum floor directly below and behind the firewall, since flames follow airflow.
3. Any ideas how to "meltproof" that area? Applying SS directly to the forward floor skin might still melt the underlying aluminum if no poor heat conductive material is placed between the SS and Al (I think).

Thanks.
Johan

[RVbySDI]

Originally Posted by Dorfie

I am planning on using Cerablanket from Mcmaster-carr.
These are the my areas of uncertainty:
Most discussions mention Aluminum foil for encapsulating the Cerablanket. 1. For engine side of firewall installation, should one not use SS foil on the engine side rather than aluminum (which will melt rather quickly I would think)?
2. Should I use aluminum foil on the other (firewall) side as encapsulating material?
Then the last question:
As in case of the RV4 fire with melted floor, I am left with clear impression that insulating the firewall alone leaves one with the risk of burn through the aluminum floor directly below and behind the firewall, since flames follow airflow.
3. Any ideas how to "meltproof" that area? Applying SS directly to the forward floor skin might still melt the underlying aluminum if no poor heat conductive material is placed between the SS and Al (I think).

Thanks.
Johan

You might want to read this thread:
http://www.vansairforce.com/communit...ulation&page=2
click on the links in post #12 of this thread for stainless (engine side)/aluminum (firewall side) foil wrapped insulation materials.


There are many other threads on firewall insulation in addition to this thread. You might do a search on firewall insulation and start reading.