Firewall! SS or Titanium?

Discussion in 'Sheet Metal' started by Taiser, Sep 19, 2015.

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  1. Sep 19, 2015 #1

    Taiser

    Taiser

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    Starting to stockpile and scrounge for metals for my Hummel H5 build this winter (Build thread will be started when I actually get going! :) ) and am thinking of titanium for the firewall instead of SS. Price isn't that bad from what I can see for the size I need (firewall is pretty small on the H5) but am wondering if there is any good reason, besides maybe a few ounces in weight) of going with the titanium FW? Never used it before so wondering how hard it is to work with, bend tabs on, etc... I know for sure I don't want galvanized! My 750 has it and I regret using it. Knowing what I know now I would have went with a custom made SS on my 750! :ermm:

    Anyhoo, anybody who has $0.02 to throw in, or has worked with Ti before, be great to get any advice!

    Cheers

    Mark
     
  2. Sep 19, 2015 #2

    djschwartz

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    There is no advantage to titanium other than weight. Thin titanium sheet can be sheared and punched with the same light duty tools you would use for stainless; however, titanium is stiffer than stainless and work hardens when formed so bending tabs will be both more difficult and present the problem that a bend not done just right the first time may be nearly impossible to "adjust".
     
  3. Sep 19, 2015 #3

    JamesG

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    OTOH, A couple of layers of Ti foil ~.005" would make a "significant" weight difference (a few ounces) and be pretty much impenetrable to heat/flame. Assuming the firewall isn't structural, of course.
     
  4. Sep 19, 2015 #4

    FritzW

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    You might want to see what kind of dissimilar metal corrosion issues there are with Titanium.

    This would be enough to scare me away from Titanium (from MIL-HDBK-1568)

    5.4.3.4 Titanium

    5.4.3.4.1 Surface considerations.
    The surfaces of titanium mill products (sheet, plate, bar, forging, casting and extrusion) shall be
    100 percent machined, chemically milled, or pickled to remove all contaminated zones and
    layers formed while the material was at elevated temperature. This includes contamination as a
    result of mill processing, heat treating and elevated temperature forming operations.

    5.4.3.4.2 Fretting.
    Titanium alloys are highly susceptible to the reduction of fatigue life by fretting at interfaces
    between titanium alloys or titanium and other metals. In any design where fretting is suspected,
    tests shall be made to determine whether such a condition will exist. Design considerations
    shall be applied to minimize fretting in structural applications.

    5.4.3.4.3 Special precautions.
    Titanium parts shall not be cadmium or silver plated. Cadmium plated clamps, tools, fixtures,
    and jigs shall not be used for fabrication or assembly of titanium components or structures.
     
    Last edited: Sep 19, 2015
  5. Sep 19, 2015 #5

    TFF

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    Many people building Competition Pitts are using Ti. I think annealed state. If nothing else its a conversation starter.
     
  6. Sep 20, 2015 #6

    BillM

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    As to corrosion issues- I know that Boeing uses titanium intercostals (stub beams) under all galleys and lavs on the commercial planes since ti resists corrosion far better than does aluminum
    BillM
     
  7. Sep 20, 2015 #7

    FritzW

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    The problem isn't urine and spilled coffee. It's when you use Cadmium plated hardware on Titanium parts, and most aircraft hardware is Cadmium plated.

    It might be okay to pee on a Titanium firewall, just don't use standard, cad plated, aircraft hardware to hold your motor mount on. ...or the gasclator, or anything else mounted to the firewall. Titanium is also damaged by Silver and lots of different lubricants and solvents.

    Titianium is good stuff but a homebuilder really needs to do his homework before using the stuff.
     
  8. Sep 20, 2015 #8

    Norman

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    It also takes a lot of shielding gas to weld
     
  9. Sep 20, 2015 #9

    Topaz

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    IMHO, use stainless and then use the money you saved to go buy your wife/girlfriend a nice dinner for putting up with your build. Or a nice dinner for enthusiastically supporting your build. You'll get far more out of that than from a titanium firewall.

    There's nothing titanium can give you that a "less cool" metal couldn't do for you at half the price, unless the design calls for titanium in the first place. As for weight savings, the paint on the airplane will weigh more than the firewall, even if you choose stainless.
     
  10. Sep 21, 2015 #10

    mcrae0104

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    Or go with galvanized so you have money for a nice bottle of wine too. Unless it's a show plane I wouldn't think anything of it.
     
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  11. Sep 21, 2015 #11

    StarJar

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    So Fritz, you're saying it's OK to pee on a firewall?
    Man, you New Mexico boys are even wilder than I thought..:ponder:..:gig:
     
    Last edited: Sep 21, 2015
  12. Sep 21, 2015 #12

    mcrae0104

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    I'm imagining a relief tube connected to a cooling spray bar. Wait, no, maybe that's not a great idea...
     
  13. Sep 21, 2015 #13

    StarJar

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    You'd want to use stainless steel.
     
  14. Sep 21, 2015 #14

    Himat

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    Stainless steel differ in one property to carbon steel that can make a difference in a firewall, the usual 316 stainless steel does not conduct heat as well as carbon steel.
     
  15. Sep 21, 2015 #15

    FritzW

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    ...it's that freaken tequila, we can't help it. ;)
     
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  16. Sep 21, 2015 #16
  17. Sep 21, 2015 #17

    Matt G.

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    How about poisonous fumes given off by the galvanizing by your engine fire, should it be close enough to the firewall to do that?
     
  18. Sep 21, 2015 #18

    Pops

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    I have built firewalls from SS and galvanized steel. SS is to hard to work with and I'm past shinny. If you don't like the look of galvanized steel, paint it.
    As far as the fumes off galvanized steel in a fire, a flying speed, the small about of fumes will be greatly deluded , so unless you have your head stuck in the flames, nothing to worry about, then you have bigger problems.
    BTW-- Have welded galvanized steel all of life.

    Dan
     
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  19. Sep 21, 2015 #19

    Taiser

    Taiser

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    That was an interesting tid-bit. Still thinking about it as well as the control rods as well and maybe the rudder pedals. Trying to make this as light as possible but maybe I'm going too far LOL. My 750 STOL is heavy so I'm trying to make this build a bit more "unique" titanium parts, flush rivets, turbine engine (eventually), etc...! Just a pure fun "S***'s and Giggle" toy! :)
     
    Last edited: Sep 21, 2015
  20. Oct 14, 2015 #20

    Angusnofangus

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    Last edited: Oct 14, 2015

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