New Lava-Like Coating Can Stop Fires In Their Tracks

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Bill-Higdon

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Interesting possibilities for fire walls
 
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From that article I'm not seeing much advantage other than surface flame propagation. What they describe is little more than a typical low fire ceramic glaze. While being non-flamable it would provide very little insulation.
 

Bigshu

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I wish there was a video with the article. The impression I got was that they did the demonstration on a horizontal sheet. How well does it cling to vertical surfaces as it melts and out gasses?
 

Stl.Ed

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Is this pretty much another intumescent paint? Several products are available to create a foamed carbon layer when heat is applied.
It seems intumescent paint has been discussed on the forum previously, but here's an interesting video demonstrating the concept (and includes a number of links in its description).


(note: this guy's channel has interesting stuff that you can spend a lot of time on :cool:)
 

Rhino

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From that article I'm not seeing much advantage other than surface flame propagation. What they describe is little more than a typical low fire ceramic glaze. While being non-flamable it would provide very little insulation.
It says it resists the conduction of heat, but it doesn't say how much. For $31.50 you can find out:

 

DanH

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Our aircraft firewall applications have a physical requirement to withstand (1) significant airflow, and (2) vibration.

Assume 2 lbs/sec cooling mass flow for a Lycoming and a 6x12 cowl exit, both fairly typical. Exit velocity at 3000 ft will be around 34 knots. Velocity will be more or less at various locations inside the cowl. Point is, it's pretty windy in there no matter where you look.

Firewalls are typically 0.019" stainless sheet or similar. Most of them vibrate to some degree at engine frequency or a multiple.

Ok, so we have a vibrating surface in a windy place. The char formed by an intumescent surface coating is generally very fragile. One I checked (Contego) mostly blew off the stainless test panel under the low velocity torch flame, and the rest fell off afterward given a little shake. I can't say the above referenced material would do better or worse, but for sure it would need a test.

The standard for "fireproof" is 15 minutes, with about 25 sq in at 2000F. Assuming the goal is simply to buy time to allow rapid controlled descent, we might pick five minutes (10K ft at 2000 fpm). The desired time frame for intact and effective insulation is somewhere in that range.
 
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Map

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Intumescent paint is used on composite airframes for fire protection, not on steel. An example where it is used on a certified airplane cowling is the Columbia series 300/350/400 (later Cessna TTX).
 

Rhino

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...The char formed by an intumescent surface coating is generally very fragile...
They have a special polymer that makes it soften and flow when heated. But since this is designed for structures, that's intended to seal gaps, not withstand vibration. So yeah, it would be interesting to see if this stood up to environmental conditions like those of an aircraft in flight.
 

raytol

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The Gliding Federation of Australia has a requirement for any glider with an engine to cover the firewall, cowlings and the fiberglass behind the engine in a product called "Firecheck 88" intumescent paint. It seems to bubble and foam up when heated and gives off H2o and Co2 as it burns. Seems to work.
 

DanH

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All good examples. I would be the first to agree intumescent paint could buy a little bit more time, and every second is valuable. I am suggesting it is not a reliable long term insulator (minutes, not seconds) on a stainless firewall. Contego definitely was not.

Intumescent paint is used on composite airframes for fire protection, not on steel. An example where it is used on a certified airplane cowling is the Columbia series 300/350/400 (later Cessna TTX).

I'd like to know more. Is there reference material available? Would you happen to know the name of the product? And do they coat just the inside of the cowling, or cowling and firewall?

Thanks!
 

raytol

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I think what is BEHIND the stainless steel/ gal steel/ titanium firewall is as important as the firewall. The Ximango wreck i own has a glass/ foam/glass
epoxy sandwich structure behind the stainless steel firewall. The aircraft had an engine oil fire caused by a split "O" ring in a pushrod tube. The pilot was climbing at 4000 feet when he smelt burning oil. He tried to stop the engine and feather the prop but the aluminum pitch change lever had melted! This meant that the prop kept rotating and the oil was still pumping! The stainless steel cowl flap had an aluminum hinge which melted and the cowl flap fell and locked so that the burning oil flowed on to the underside of the fuselage. The pilot reported that he could not keep his feet on the rudder peddles due to the heat. The fuselage was burnt almost to the tailwheel. As the pilot dived towards a lake the fiberglass upper engine cowl softened and bulged between the fasteners. The battery exploded through the cowling. The fire now flowed on to the foredeck and started to melt the canopy. He managed to mostly open the canopy before it jammed. The heat coming through the firewall ignited the aircraft brake fluid and the compass exploded. The aluminum instrument panel saved him even though all the plastic instruments were on fire. The pilot put the aircraft down in water and managed to put the fire out.
Learning from this:
(a) Don't make anything critical in the engine bay out of aluminum, including the prop- control or cowl flap hinge.
(b) Don't use foam/ fiberglass sandwich behind the firewall, I only use plywood now. Much stronger for longer.
(c) Put a fire resistant and heat insulation blanket or material on the pilot side of the firewall and use extra cover over the engine bolts and intrusions.
(d) use a stainless steel strip in the cowling layup to support the cowl fasteners.
(e) don't put the battery in the engine bay
(f) Don't use nylock nuts anywhere in the engine bay and lots more!
 

DanH

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Good report. Agree all, with one exception.

Re (c), burn tests have shown appropriate insulation methods on the engine side of the firewall to be far superior to any form of cabin side insulation. Occupant heating, structural protection, and smoke generation are all factors. The goal is to remain in control of an intact aircraft, while being able to see and breathe.

BTW, many of the cabin side "firewall insulation" products tested were far worse than no product at all. Seriously worse.
 

rv7charlie

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For those who don't know DanH from over on the VAF forum, I'd suggest spending a week (or maybe a month) reading through the testing & major projects he's documented over there. Actual testing of some of the products he's talking about are documented there.

Hey Dan,

Congrats on your retirement!

Charlie
 

raytol

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Good report. Agree all, with one exception.

Re (c), burn tests have shown appropriate insulation methods on the engine side of the firewall to be far superior to any form of cabin side insulation. Occupant heating, structural protection, and smoke generation are all factors. The goal is to remain in control of an intact aircraft, while being able to see and breathe.

BTW, many of the cabin side "firewall insulation" products tested were far worse than no product at all. Seriously worse.
Yes, I agree. I have gone back to just putting a layer of Fiberfrax and another layer of plywood on the pilots side of the firewall. I am hoping to stop the penetration of heat in to the inhabited area. We need every bit of knowledge we can get in this area!
Can I see your test results online please Dan. Ray
 

gtae07

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Search "firewall insulation" on VAF. One example:

There are lots more there, too.

In addition to actual testing of firewall protection methods, Dan has also written some good posts on painting and finishing techniques, and fiberglass fabrication for metal builders. He's a good resource.
 
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