[roc-chat] Re: ROC Launch Control System
- From: "Chris Feenstra" <chris.feenstra@xxxxxxxxxxx>
- To: <roc-chat@xxxxxxxxxxxxx>
- Date: Thu, 11 Oct 2012 20:41:02 -0700
Comments concerning a possible new launch system:
1. The existing launch system is a non-digital, analog system. It uses
switches, relays and some solid state devices (transistors, optical
isolators, etc). It is relatively simple, and it has proven to be very
reliable and safe. We would have to be having serious problems with the old
system, and we would have to have a very good replacement to make it worth
replacing the old system.
2. If we were to replace the launch system, I would suggest a phased
approach. Perhaps have the old and new systems side by side for a few
launches while we test and verify the new system. Or we should develop the
new system for a few away pads, and once we are ready, and the new system is
up to it, expand it as needed.
3. I do not consider having individual wireless launch pads to be
practical. This would require each pad to have a battery and a wireless
launch receiver. This would be costly. It would also mean that the range
head would have to maintain communications with 54 wireless launch
receivers, instead of 9. (Assuming the new system matches the existing
system which handles 54 pads).
4. I would consider unidirectional communication from the controller
to the receivers only to be unacceptable. I would want the controller to
know the status of the receivers, and be able to report any faults or loss
of communications.
5. Shunt and power switches do not prevent rocket launch if the
switches are set for a rocket launch and the wireless receiver decides to
launch. Any system would have to be built to minimize risk of launches when
we don't want them.
6. As for launch system safety, the greatest risk is if the launch
system launches when it isn't supposed to. There are ways to minimize this.
I would include:
a. Two way communications so that the controller can monitor the
status of the pad receivers. This would include the status of the receiver
(the state of every launch pad), the battery voltage, etc. If the controller
did not receive status for too long, or detected a status that is different
than it should be, it could alert the LCO and try to force the receiver to
go into a "failsafe" mode, with all relays off.
b. A "heartbeat" circuit that the CPU would have to reset periodically,
as it cycles through its tasks. That way, if the CPU hangs, the heartbeat
circuit could detect this. It would then force the receiver into a
"failsafe" mode with all launch relays off, and perhaps reset the CPU. The
circuit would also make sure that the launch relays are all off while the
CPU boots or reboots.
7. The launch receivers should:
a. Be as identical as possible, for ease of construction, and to make
it easy to swap receivers if there are problems.
b. Handle a set number of pads, such as six like the existing system.
c. Have audio and perhaps visual alerts indicating its status.
d. Have continuity test buttons for each pad.
e. Have a battery inside the case. The battery would be easily
replaceable.
f. Have a case with a lid that can be shut while the launch wires are
attached. That way, if weather hits, we would simply close the lids. Perhaps
we could use a modified tool box.
g. At least some of the receivers should be set up so that a larger
external battery can be connected if needed.
h. Have a handle for easy carrying, and not be too heavy.
8. Any electronics will have to be able to withstand a wide range of
temperatures. It gets HOT out on that lakebed in the summer.
Chris Feenstra
NAR #61291
Tripoli #9123
Level 2
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx]
On Behalf Of Richard
Sent: Tuesday, October 09, 2012 8:50 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: ROC Launch Control System
Ok, I'll put together a couple of concepts that should give us a good idea
of what we are looking at. The technology is available and we have time to
investigate what we want and what we can do. There is a good deal that is
need to be done before we can start a final design.
1. SAFETY!!!
2. A wish list (all ideas even the outlandish, pie in the sky kind, you
would be surprised how many good ideas are inspired by crazy comments) hold
nothing back.
3. SAFETY!!!
4. Environmental the lake bed is: Hot, Cold, Windy, Dusty, Salty, static
electricity, very sunny(UV) and sometimes wet! We need to run test on just
how hot will a box with active electronics get at June ROCStock or Aug.
launch (most commercial temperature grade electronics are rated to 85C or
185F)? Freezing is hard on batteries etc.
5. SAFETY!!!
6 .Useability how easy are they to operate, handling, setup, maintain, etc.
Gorilla proofing is no joke it has to be gorilla proof! That is why we need
local arming and shunts.
7. SAFETY!!!
8. Power how much power do we need? Be aware our current system is mostly a
passive system it uses little or no power while sitting waiting for launch.
A new system that is wireless will need power all the time. Parts of it can
be put to sleep to save power and this will help, but power management will
be a priority after SAFETY!!!.
9. SAFETY!!!
10. Cost!
11. SAFETY!!!
I don't know who would like to keep track of the wish list but here is what
we have so far.
1. Wireless system individual pad controller with shunt and local arming a
safe distance away from pad.
2. Data collection battery status, how long has rocket been waiting on the
pad, etc.
3. Automate the pad assignment and check in process ( I said outlandish).
James and Ron before you read this I what to encourage all ideas to be put
on the table to weight the pros and cons.
Not to offend but:
"One thing I've pinged around with Ron is the idea of a Wireless relay.
It would hookup to the existing ROC/TCC relay boxes and just act
as a cable replacement."
This is a very bad idea without adding safety shunts and local arming here
is why.
The wireless relay electronics can get stupid, static, software...etc..
The driver transistor or MOSFET can fail, shorting ON 80% of the time.
I'm sorry to offend but it's a bad very unsafe idea. I would rather see new
cables and connectors installed. The current launch boxes were designed for
cables leave it that way! If you want wireless then design a system based on
wireless from the beginning.
At some point we will have to make some kind of decision because while the
launch system has a flawless record due in part to a all wired system, it
will become less reliable and less safe as the cables deteriorate. I was
shocked at what tape on the break in the outer insulation had done. What if
in the future the inner wires break or fray? So, we have time lets us use
the time wisely and make a well informed decision. The easiest and cheapest
is replace the cables and connectors. The is no halfway: a car is a great
land vehicle and a boat is a great water vehicle, and you can make a car a
boat and a boat a car but it will never be great at ether task.
Thanks I hope I didn't offend too much the Wright brothers argued all the
time and look what they did!
Thanks
Richard C Hall
TRA# 11515 AF6IH
-- ROC-Chat mailing list roc-chat@xxxxxxxxxxxxx
//www.freelists.org/list/roc-chat
Other related posts:
