Interesting idea for the pneumatically controlled switch. If you had a
micro-sized air actuator connected to a switch or circuit breaker, you
could use clear plastic tubing that slips off at launch to run it.
At some point I may need remote pressurization but for now I'm sticking
to certified tanks and 3000 psi rated valves for the high pressure
helium. I was happy when I realized the Swagelok 4P4T plug valve could
be run by the servo - that made for a lightweight high pressure
solution. The vent valves will remain open until just before launch
(and they are fairly large - 3/8 inch) so a helium valve leak would just
bleed out the tank vents.
You know, one thing that I realized with all this talk about lockouts,
is that if something goes really wrong, I would rather have a normal
start than a hard start. For a liquid, it wouldn't do any good to just
lock out the igniter and not also the main valve because if the main
valve opened on its own and had no ignition, that's a more dangerous
situation in my opinion. But locking out all of them is straightforward.
-Bob
On 11/10/2015 03:38 AM, Monroe L. King Jr. wrote:
One more thing and I'll shut up for a while. On a pressure feed rocket
locking out the pressurant may be more practical as without that the
open supply lines would not leak much fuel past the injectors.
Remote filling of the pressurant would be easier than remote fuel and
oxidizer filling.
It would also be very easy to put a leak detector below the nozzle to
give pad workers time to lockout the main valves or run.
A sufficient size vent valve would prevent lox from building up pressure
to feed it's self during filling.
-------- Original Message --------
Subject: [AR] Re: Safing of liquid vehicle
From: "Monroe L. King Jr." <monroe@xxxxxxxxxxxxxxxxxx>
Date: Tue, November 10, 2015 2:02 am
To: arocket@xxxxxxxxxxxxx
You could double up on that by locking out the main valves with a second
switch.
I would also use mechanical removable lock out devices on the supply
lines.
Remote filling would become a factor at some point. That point would be
when I felt a tank rupture would kill people on the pad flying pieces
not withstanding. (when protective clothing and gear would not be
sufficient)
-------- Original Message --------
Subject: [AR] Re: Safing of liquid vehicle
From: "Monroe L. King Jr." <monroe@xxxxxxxxxxxxxxxxxx>
Date: Tue, November 10, 2015 1:47 am
To: arocket@xxxxxxxxxxxxx
I think a pneumatic switch near the pad would be the best solution. Have
that switch activate your circuit breaker for main power.
I think primary logic systems could safely be activated and the ground
crew could monitor systems other than main control such as telemetry and
comms.
All main control systems would be tied to that main breaker and
inoperative during pad operations. Allowing other on board systems to be
active.
The line on the pressurizing end of the pneumatic switch would not be
connected until the pad is clear.
