Ben: I have been blessed to be in a position where costs are not generally
considered. Ergo I have no idea how much they actually cost. I can't even
bound it.
Jon: The surface stress generated by the NiTi is past yield point of all
reasonable rocketry alloys. Somewhere in the order of 100ksi contact
stress, based on my eye-crometer, looking at bite depths. That means that
if you prep your fitting and your tube well, it should be vacuum tight to
your requirements. However, since you will be flowing ln2, you would have
to consider the effects of the temperature on the shape memory effect.
Oddly enough, my experience with them (having them custom made by a trusted
partner) is for structural reasons, not fluid containment. We were trying
to replace bolt heads with them, and almost made it work.
On Sat, Dec 22, 2018 at 7:47 PM Ben Brockert <wikkit@xxxxxxxxx> wrote:
They say “less costly” which is usually code for “very expensive”. Have
you priced them?
On Saturday, December 22, 2018, Michael Clive <zeinin@xxxxxxxxx> wrote:
I strongly suggest Cryofit couplings. I have not used them specifically,
but I have developed a similar technology. I think Cryofit can just sell
you the fittings for whatever tube you want.
On Sat, Dec 22, 2018 at 1:35 PM Ben Brockert <wikkit@xxxxxxxxx> wrote:
JPL says they can do it. I'd be hesitant to base a design on something
only JPL has the capability of, but there's proof of concept.
I haven't seen a lot of autogenous welding in aluminum, and orbital
tube welders are usually autogenous welders. Can make inserts but it
makes the whole thing a bit more of a hassle.
On Fri, Dec 21, 2018 at 11:33 AM Paul Breed <paul@xxxxxxxxxx> wrote:
1/2") aluminum tube?
Does anyone have any experience with orbital welding of small (1/4",
for aluminum?
I've seen it done for stainless, but I'm wondering if it can be done
Paul