Author Topic: RW materials question for the Whiffverse:  (Read 6953 times)

Offline Daryl J.

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RW materials question for the Whiffverse:
« on: January 04, 2014, 08:18:51 AM »
The question: at what speed is it better to use titanium instead to aluminum in an airframe?  The follow-on question:  is it possible to have the high friction areas be titanium instead of aluminum on airframes, presuming an existing platform is being subjected to modifications?

Yes, this is a recce Phantom question. :)

Greg and I was chatting at the Spruce Goose Museum last year and he told of a certain high speed run that ruined some newly applied paint.   And there are rumors of some very high speed events with Syrian MiG-25s and Israeli Phantoms.   It kicked my OCD/AMS (aka imagination) in to gear.  :D.   And the Academy thin wing Phantom showed up today.  Mmmmm!  Thus the questions.

Thanks in advance,
Daryl j.
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Offline Cliffy B

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Re: RW materials question for the Whiffverse:
« Reply #1 on: January 04, 2014, 08:56:22 AM »
Keep in mind I'm not a metallurgist or aeronautical engineer but just considering the melting points of the two metals in question I'd go with titanium in the high heat areas and definitely not aluminum.  Aluminum will melt at around 1,200 degrees Fahrenheit and titanium at over 3,000.  If you can carry the extra weight, use the titanium.

Again, just the opinion of whiffer and Google  ;D
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Offline Daryl J.

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Re: RW materials question for the Whiffverse:
« Reply #2 on: January 04, 2014, 09:18:57 AM »
I'm thinking in terms of heat resistance, yes, but also things like coefficients of expansion, stiffness compatibilties, galvanic corrosion resistance, etc.   I'm utterly oblivious.   :-[

As little time as I have to model any more and given that I prefer a Near-RW Whifbuild, having something reasonably plausible it is the goal.   Ah, the things I choose to torment myself with!  ;D

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Offline Cliffy B

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Re: RW materials question for the Whiffverse:
« Reply #3 on: January 04, 2014, 09:19:59 AM »
Since it'll be high heat, it'll probably be unpainted right?  Just paint various natural metal shades and call it a special "alloy".  See, problem solved  ;D
"Radials growl, inlines purr, jets blow!"  -Anonymous

"Helos don't fly.  They vibrate so violently that the ground rejects them."  -Tom Clancy

"If all else fails, call in an air strike."  -Anonymous

Offline elmayerle

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Re: RW materials question for the Whiffverse:
« Reply #4 on: January 04, 2014, 03:22:20 PM »
Biggest problem in substituting titanium for aluminum is that you suddenly have all sorts of galvanic corrosion potentials that you didn't have before and you may need special sealants and/or surface finishes.  That's something I deal with a fair bit, given that I'm currently working with structure around propulsion systems.

Offline Daryl J.

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Re: RW materials question for the Whiffverse:
« Reply #5 on: January 04, 2014, 04:49:12 PM »
Thought so.   Thanks.
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Offline GTX_Admin

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Re: RW materials question for the Whiffverse:
« Reply #6 on: January 04, 2014, 04:55:41 PM »
Interestingly though plastics reinforced with carbon fibers can induce galvanic corrosion in attached aluminum components.  This is one of the reasons why Titanium is finding greater application in platforms like the F-35 and 787.  Titanium does not suffer to the same extent.
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Offline Daryl J.

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Re: RW materials question for the Whiffverse:
« Reply #7 on: January 04, 2014, 05:07:40 PM »
Well how about that.   That was the next question.

Going back to all aluminum, are there ceramic coatings that adequately deflect/absorb heat that can be used on leading edges and other high heat areas?   
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Offline kitnut617

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Re: RW materials question for the Whiffverse:
« Reply #8 on: January 04, 2014, 11:28:39 PM »
Some time ago I was reading an article in a motorcycle magazine, it was about futuristic MotoGP engines that would rev to over 25,000 rpm (or even higher).  The plan was to use ceramic pistons, valves, heads and cylinder liners because of the heat generated while operating at these elevated rpms.  I don't know what ceramic was involved though --

Offline GTX_Admin

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Re: RW materials question for the Whiffverse:
« Reply #9 on: January 05, 2014, 03:18:06 AM »
Another option (rather than simply change materials) is to introduce an active cooling system for the affected parts, probably using fuel as a coolant.
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Offline GTX_Admin

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Re: RW materials question for the Whiffverse:
« Reply #10 on: January 05, 2014, 03:22:00 AM »
It might depend upon the intended operational profile.  If only expecting to experience short term high temperatures, one might just as easily utilise an ablative coating to the affected areas - this could be replaced during BF/AF maintenance perhaps.  If however one wanted to deal with far longer term operations, one could consider some of the coatings utilised in gas turbine engines.
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Offline Daryl J.

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Re: RW materials question for the Whiffverse:
« Reply #11 on: January 05, 2014, 04:05:26 AM »
Useful info.    :)

Thanks!

Where I hope to take this is a Photo Phantom variant with shorter high speed dashes available to it say, for instance, the higher Mach 2's. Alternative intakes, materials where appropriate,  recce setup, and nation of use.     Kit of choice is the Academy F-4B for the thin wing.   Eventually.
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Offline GTX_Admin

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Re: RW materials question for the Whiffverse:
« Reply #12 on: January 05, 2014, 04:24:04 AM »
I assume something in the '60s/'70s era?
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Offline GTX_Admin

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Re: RW materials question for the Whiffverse:
« Reply #13 on: January 05, 2014, 04:35:48 AM »
Speaking of ablative coatings on aircraft, the X-15 is probably the most extreme example - click on image for more details:

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Offline Daryl J.

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Re: RW materials question for the Whiffverse:
« Reply #14 on: January 05, 2014, 04:51:33 AM »
Quote
I assume something in the '60s/'70s era?

Correct.
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