Fair enough, I was comparing to a government run Lox Kerosene engine I had
direct contact with, so prices were probably exaggerated. Its not a violation
of "safety rules" if you determine that the risk associated with having
peroxide temporarily contact a non ideal material is insignificant, and that
the gains from foregoing such stringent standards far outweigh the negatives. I
take it you did everything by the book then at armadillo?
Ib
From: wikkit@xxxxxxxxx
Date: Tue, 6 Sep 2016 18:14:20 -0400
Subject: [AR] Re: Issues with operating at low chamber pressure
To: arocket@xxxxxxxxxxxxx
I can get you a quote for $2000 for a peroxide valve, that doesn't mean much.
You can skimp on oxidizer cleaning if you want, but I don't think it's
particularly relevant to argue that one thing is cheaper than another if and
only if you violate safety rules.
On Tuesday, September 6, 2016, ignacio belieres <ignacio_belieres@xxxxxxxxxxx>
wrote:
Ben, I have heard quotes of over 1000 usd for 1 inch full port cryo
valves. A regular SS 304steel ball valve to be used with hydrogen peroxide
would run you under 60 bucks. And if you bring up compatibility, for the time
they are exposed to 98% h2o2, decomposition is minimal and has posed no danger
in my experience. The only components that have to be truly rated for
indefinite exposure to peroxide are the main storage tanks, which are not that
big of a deal.
Cheers,
IBFrom: wclaybaugh2@xxxxxxxxx
Subject: [AR] Re: Issues with operating at low chamber pressure
Date: Tue, 6 Sep 2016 16:56:50 -0400
To: arocket@xxxxxxxxxxxxx
20x cost savings may be a little aggressive: there isn't any significant
mechanical or materials difference between valves using those two oxidizers.
Insulation is very cheap; at most you might want a slightly more powerful drive
for Lox, just in case.
Bill
Sent from my Commodore 64
On Sep 6, 2016, at 4:41 PM, ignacio belieres <ignacio_belieres@xxxxxxxxxxx>
wrote:
Henry, Well if you accept the correlation that cost tends to go up
with dry mass, and that volume is in a direct relationship to dry mass, then
using a smaller vehicle for a same payload will reduce cost. The difference is
even more pronounced than that because with a room temperature liquid
propellant you dont have to deal with cryofluids, prechills, cryovalves,
insulation, reaally good thermal control, lox vents, and extra annoying stuff.
A peroxide compatible 1 inch ball valve will probably be 20 times less
expensive than an equivalent Lox valve.
IB
Date: Tue, 6 Sep 2016 14:31:25 -0400
From: hspencer@xxxxxxxxxxxxx
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Issues with operating at low chamber pressure
On Tue, 6 Sep 2016, Troy Prideaux wrote:
Anyway, it turned out the combination producing the lowest Isp actually
produced the highest delta V return primarily due to the respective
densities on offer which directly affected the respective mass ratios for
the volume fixed analysis...
There are occasional observations going back to the 1950s about how denser
fuels often seemed to produce higher performance in real rockets, even if
they incurred an Isp penalty.
That said, any constant-volume analysis is going to be somewhat biased in
favor of denser fuels, in the same way that any constant-gross-mass
analysis is going to favor the highest possible Isp: the conditions of
the analysis have stacked the deck somewhat. The yardstick that's really
of the most interest is not volume or mass, but cost -- defined broadly,
to include issues like operations difficulty as well as cash outlay -- but
that's harder to estimate well for a paper design.
Henry
