There is another material not mentioned probably because of cost, but if
money were not an issue, there's Maraging steel. The M-250 grade was used
in the Aerojet
260 '' solid rocket motor of the 60's and was used in the Truax SEALAR
LOx/Kerosene flight rocket tankage of the. 80's. With a yield of 240 KSI
it's up there with titanium strength/weight. SG is 8.
And there's 300 and 350 grades but with corresponding lower elongation.
Ken
On Tue, Jan 11, 2022 at 1:29 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>
wrote:
The quick comparison I did a year or 2 ago:
*Tube Material Comparison*
*Material*
*OD*
*Wall*
*Density*
*Yield Str*
*Max Press*
*Max Pressure*
*Wt*
*Capacity*
*(mm)*
*(mm)*
*(g/cc)*
*(Mpa)*
*(Mpa)*
*(Psi)*
*(Kg/mtr)*
*(m^3/mtr)*
6061-T6
152.4
3.175
2.7
241
10.04
1456
4.02
0.0168
Ti-6Al-4V
152.4
1
4.43
880
11.55
1675
2.11
0.0178
316 SS
152.4
2
8
290
7.61
1104
7.56
0.0173
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *Troy Prideaux
*Sent:* Wednesday, 12 January 2022 8:24 AM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: fiberglass conduit
Bill,
I’ve only looked at it regarding some numbers – not pricing. I was
assuming it to be much more costly than that so I never bothered
investigating it further. It certainly is appealing in particular for
something like a hybrid tank where you can weld heavier ends on for non
protruding coupling. For a tank, the thinner wall not only reduces dry
weight per unit section, it also increases wet mass loading per given
section. The same would apply to a solid, and you can probably reduce your
liner margin somewhat – especially for regressive pressure profiles as the
material will handle much more heat than AL-alloys for even more additional
wet mass loading.
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx
<arocket-bounce@xxxxxxxxxxxxx>] *On Behalf Of *William Claybaugh
*Sent:* Wednesday, 12 January 2022 5:11 AM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: fiberglass conduit
John:
Have you or anyone you know ever looked at Titanium tubing? I’m finding
that 0.050” wall 6” outside diameter tube can be had for around $700 per
60” length vs. about $240 for an aluminum tube at 0.125” wall.
That would come in at about two-thirds the weight of the aluminum tube,
saving three pounds or about 10% of the current dry mass of my 6” motor.
It would require going to button head fasteners rather than countersunk so
drag would go up some but that weight savings appears to be worth an about
10% altitude gain and thus might be worth the extra $500 per flight.
Bill
On Tue, Jan 11, 2022 at 9:17 AM John DeMar <jsdemar@xxxxxxxxx> wrote:
The phenolic looks interesting as a motor casing. They spec axial tensile
strength but not radial. 60% the weight of aluminum but only 17% the
tensile strength. There goes the weight advantage unless one adds a carbon
fiber overwrap. And hydrostatic tests it. Still, there's the issue of
attaching closures to the tubing... appropriate adhesive, plus pinning,
plus insulation.
-John DeMar
Las Cruces, NM
On Tue, Jan 11, 2022 at 8:16 AM James Fackert <jimfackert@xxxxxxxxx>
wrote:
maybe of interest for airframes and solid motor builders-
championfiberglass.com
has glass epoxy and phenolic epoxy conduit in 3/3" to 8" sizes, three wall
thicknesses, 10 foot lengths
lots of coupling anf fitting options
even split clamp over repair/reinforcement tubes.
should be reasonable prices since its a commercial product.
