Fire wall Ti?

[Stitspb]

I have a homebuilt and am thinking of putting a titanium fire wall on. I am not sure what size or grade to use? Any help would be great thank you.

[WLIU]

I'll bite. What is the engineering rationale for use Ti? The alternatives are easier to machine and lend themselves better to being shaped if you need a non-flat forewall.

The FAA specs for farewalls dictate the thickness of material that you require. A firewall needs to be able to handle a 2000 degree heat source for several minutes. If you have seen a firewall burnt through due to a failure in an exhaust system (I have), you will believe the spec. So you have to calculate how thick your material needs to be to resist the high temperature erosion for that long. Look in FAR 23 and its derivatives for the exact spec.

Best of luck,

Wes
N78PS

[Dave Prizio]

Titanium is a great choice for an airplane firewall, exept for the cost, of course. However you might be able to find some scrap material for around $200 that would be big enough to do a firewall. You need a thickness of .016 to .020 in. If you go any thicker you start losing the advantage of titanium's lighter weight. Commercial pure titanium is your best bet if you can find it. It has the lowest tensile strength, which is not really important, and is therefore easier to work with -- cut, make holes in ,etc.

The 6AL-4V alloy seems to be much more readily available but it is twice as strong and thus harder to work with.

When cutting or drilling titanium be sure to go slow and provide lots of lubrication for cooling. It tends to gum up tooling because of its poor heat transfer qualities. In fact it conducts heat about 10 times less efficiently than steel, which makes it great as a firewall material.

A titanium firewall can save about 2 pounds as compared to stainless steel on the typical single-engine airplane.

[WLIU]

What would a sheet of Ti say 42"w x 30"h cost?

Regards,

Wes
N78PS

[CraigCantwell]

From Online Metals, Ti Grade 2 sheet, .028" thick, 48"x 36" runs about 400$ plus shipping. I don't know what they are calling grade 2 alloy wise, you would have to call. Stainless is going to be 1/5th or less in cost.

[Stitspb]

Thank you all for your input. The reason Ii want Ti is to reduce weight I am rebuilding a Stitts SA3-B Playboy and I want it lite. Also a Ti fire wall will look so clean. I won't be forming it, so I only have to cut it to size and drill holes.