[AR] Re: Intertank coupling design
- From: Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Tue, 29 Oct 2013 20:23:10 -0400
My experience leaves me with a slightly different take: things cost what they
cost for reasons--typically having to do with the actual cost of making the
thing or providing the service.
I've had 6061tanks welded, heat treated, and stretched back to round. They cost
some--and that is a part of the reason I now focus on solids that use no welds.
But it seems to me fairly likely that the alternatives all cost out as
similarly or more costly, otherwise we would all be doing something else,
because it was less costly....
There are many things in this game that can appear to be done at much lower
cost by accepting lower performance, but performance is, ultimately, a metric
that is measurable in dollars.
Bill
Sent from my iPhone
On Oct 29, 2013, at 19:59, Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx> wrote:
> Bringing a welded 6061 tank back up to T6 is definitely something you want to
> contract out to pros. That said, if you can find a shop with a big enough
> annealing tank for your tank, and a good track record, and you need the
> performance, it might be worth the (fairly stiff) price.
>
> Chances are a shop that can do that can also weld up the tank for you, by the
> way. Not cheap either, but depending on whether you'd rather be learning to
> weld your own aluminum of bypassing that and flying rockets, possibly also
> worthwhile.
>
> As with all of this stuff, it's always worth seeing if you can get the shop
> to give you a discount for the coolness factor...
>
> Henry
>
> On 10/29/2013 2:48 PM, Ben Brockert wrote:
>> Bringing 6061 tanks up to T6 is a pain in the ass because it involves
>> solution annealing, which requires getting the tank frighteningly close
>> to melting and then quenching rapidly with water or a lot of cool gas.
>> Doing it without collapsing or warping the tank requires careful setup
>> and skilled operators. The tank can be straightened after the quench,
>> but that requires another, possibly complex, setup.
>>
>> Instead, skipping the solution anneal and going straight to artificial
>> aging can give you results of 6061-T5, without nearly as much hassle.
>> It's an improvement of about 50% in tensile strength. It just requires
>> an oven that the part can fit in, which for tanks those size could
>> probably be done at a powder coating shop. There are a lot of different
>> formulas for artificial aging, usually two heats of two to eighteen
>> hours each, at temperatures between 300 and 400F. Higher temperatures
>> take shorter times; normal aging would be to let the part sit at a
>> warmish room temperature for a year or two.
>>
>> Still well short of the state of the art in 6000 series rocket tanks but
>> a useful and achievable improvement over as-welded condition.
>>
>> Ben
>>
>> On Tue, Oct 29, 2013 at 2:56 PM, Carl Tedesco <ctedesco@xxxxxxxxxxxxxx
>> <mailto:ctedesco@xxxxxxxxxxxxxx>> wrote:
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