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 Post subject: Re: Titanium Foil
PostPosted: Mon Oct 14, 2013 3:59 pm 
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Location: rhode island
so,
i know you mentioned that you were experimenting with different materials...
why Ti instead of Al ?
(Ti is heavier)

do you have a cheap source for this stuff?
what sheet metal skills do you have?
bending the spanwise profile can't be much easier than any of the machine operations.

can you do for-aft camber for the lift profile?
despite any conserns over flat plate for wing sections they still work.
maybe not as forgiving , but its a good start.

i've seen lots of boats with plates for keels and propellors with no thichness profile.
besides , bondo is cheap.

very cool


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 Post subject: Re: Titanium Foil
PostPosted: Mon Oct 14, 2013 6:41 pm 
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zfennell wrote:
so,
i know you mentioned that you were experimenting with different materials...
why Ti instead of Al ?
(Ti is heavier)

do you have a cheap source for this stuff?
what sheet metal skills do you have?
bending the spanwise profile can't be much easier than any of the machine operations.

can you do for-aft camber for the lift profile?
despite any conserns over flat plate for wing sections they still work.
maybe not as forgiving , but its a good start.

i've seen lots of boats with plates for keels and propellors with no thichness profile.
besides , bondo is cheap.

very cool


My first experiment was Aluminum, it failed.
So I tried wood and titanium, and is very happy with the results..
I bought titanium off eBay.
I have not worked with metal before.
Bending is something I am still trying to figure out.
With high AR titanium plate will work wonders,
With low AR, wood will be better with the foil shape.
Mahalo


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 Post subject: Re: Titanium Foil
PostPosted: Mon Oct 14, 2013 6:43 pm 
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Titanium is stronger then aluminum for a given mass.


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 Post subject: Re: Titanium Foil
PostPosted: Mon Oct 14, 2013 9:16 pm 
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Location: rhode island
"My first experiment was Aluminum, it failed."........

Thanks for that.
Any opinions why the aluminum did not work for you?
(Stiffness, strength, corrosion?

-bill


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 Post subject: Re: Titanium Foil
PostPosted: Mon Oct 14, 2013 9:36 pm 
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zfennell wrote:
"My first experiment was Aluminum, it failed."........

Thanks for that.
Any opinions why the aluminum did not work for you?
(Stiffness, strength, corrosion?

-bill

I used three layers of aluminum signs that was just laying around, I knew one sheet was too weak, they are probably 2mm thick each. They are too soft, there are better aluminum alloys, but my second test was the titanium. One 2mm sheet was strong enough.


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 Post subject: Re: Titanium Foil
PostPosted: Mon Oct 14, 2013 9:51 pm 
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Location: Miami @ 6" Flat Butter!
I don't see why 6061 T6 Aircraft Grade Aluminum wouldn't work :?:
Especially when a surface generated on a Cad Cam program (Master Cam for example).
Than the G-Code could be loaded it up to a CNC 3 - 4 Axes Machine
and what you got is a solid 1 peace of lower portion of the hydrofoil,
which is perhaps indestructible, what I'm thinking :idea:

DrLW


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 Post subject: Re: Titanium Foil
PostPosted: Tue Oct 15, 2013 12:18 am 
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The front wing on the Rush Randle foil board is 8mm thick aluminum, by using 2mm
Titanium, I have cut down the cross section drag to 25%.


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 Post subject: Re: Titanium Foil
PostPosted: Tue Oct 15, 2013 12:59 am 
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Doubling the signs does not improve strength as much as one thicker piece.

7075-T6 (65,000 psi yield) is better or 7068-T6 (95,000 psi yeild) is best for aluminum. In fact, 7068-T6 is almost as strong as aircraft grade titanium.

If using titanium, there is a big difference from pure titanium (40,000 psi yield) vs aircraft grade titanium Ti-6Al-4V with 6% aluminum and 4% vanadium (120,000 psi yield).

Interesting thing is the stiffness (modulus of elasticity) is not much different between aluminum and titanium.
Aluminum 10,000 psi modulus
Titanium 16,000 psi modulus
Stainless Steel 30,000 psi modulus


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 Post subject: Re: Titanium Foil
PostPosted: Tue Oct 15, 2013 1:41 am 
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gbleck wrote:
Titanium is stronger then aluminum for a given mass.


That depends on the alloy and heat treatment being compared.

http://precisionarmament.com/tennalum-7068-aluminum-alloy/

https://online.kaiseraluminum.com/depot/PublicProductInformation/Document/1033/Kaiser_Aluminum_Alloy_7068_Brochure.pdf

Image


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 Post subject: Re: Titanium Foil
PostPosted: Tue Oct 15, 2013 2:58 am 
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The titanium that I use is 6Al 6V-2Sn, which is stronger than the 6Al 4V


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