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  #21  
Old August 23rd 18, 11:35 AM posted to sci.space.policy
Jeff Findley[_6_]
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In article ,
says...

Jeff Findley wrote on Wed, 22 Aug 2018
06:41:34 -0400:

The STS-1 was a mistake. There
were several issues with that first flight that could have resulted in
LOC.


They didn't have a choice. Fly it unmanned and it was a guaranteed
loss of vehicle, since the thing couldn't land without a pilot.


And yet, post Columbia, NASA came up with a set of jumper wires to
install which allowed for a completely uncrewed landing. While the
space shuttle was originally designed to require pilots, there was
actually very little which prevented it from landing uncrewed. Mostly
it amounted to the computer not being able to throw a couple of switches
(hence the jumper wires).


For current uncrewed test flights using off the shelf crash test dummies
(i.e. min size female and max size male) is the cheapest way to
instrument the vehicle to see what accelerations the meat bags will have
to endure.


You get the same data without the dummies from sensors on the capsule.


Mostly. But, the instrumented dummies give you direct data on what the
human would experience.

For example, if there were an issue with the seat structure (say the
vibration dampers built into the seat supports), you wouldn't know it
just by instrumenting the capsule itself. That is, unless stick
instrumented mass simulators in the seats to simulate a human. Which
very quickly turns into simply using an off the shelf, instrumented,
crash test dummy since that's exactly what they are. They're
essentially high fidelity human mass simulators.

Jeff
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  #22  
Old August 23rd 18, 11:40 AM posted to sci.space.policy
Jeff Findley[_6_]
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In article ,
says...


However, during crew ingress when the hatch is opened and there are both
flilght cerws and pad crews in capsule, doubtful that the capsule
jettison would be armed. So egress via bridge and then down the zip line
more likely.


During crew ingress, the launch vehicle isn't at all fueled. It's a
giant empty aluminum can. So the likelihood that something "bad" would
happen at that point is very minimal. The only thing I could think of
that would trigger such an evacuation would be a problem with the
capsule itself. But in that case, I'd think taking the elevator down
would be safer. Depends on the emergency though.

With fueling happening after crew are strapped in and hatches closed,
the odds of problems while crews get into capsule are much lower.

At the time crews will ingress, will any part of the stack be alreayd
fueled?


Only the capsule. The launch vehicle would literally be "bone dry".

Or does fueling "at last minute" involved fueling not only stage
1, but also stage 2 and fuel inside Dragon ?


The hypergols in Dragon 2 are loaded before it's rolled out to the pad,
just like all other capsules and the space shuttle did. SpaceX isn't
changing that part of the procedures at all.

Jeff
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  #23  
Old August 23rd 18, 11:49 AM posted to sci.space.policy
Jeff Findley[_6_]
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In article ,
says...
So I'm still puzzled at the actual utility of such a system.


It's simply a "feel good" measure, just like the pre-Challenger
motorcycle style helmets that the crew wore during launch. They weren't
sealed and were connected to air bottles, not pure oxygen. They were
supposedly there for scenarios like the cabin filling with smoke, but
that rings hollow due to them not being sealed and not having pure
oxygen connected to them. It was all very "half-assed".

And again, it lets the astronauts do more "safety" training by sliding
down the ziplines, jumping in the armored vehicle, and driving away from
the pad.

It's not at all different than the "duck and cover" drills which used to
happen in US schools supposedly to protect the children during a nuclear
war. I'm sure at the time everyone knew it was a farce, but went
through the motions anyway.

The certifications for passenger aircraft evacuations are only a bit
better because the people are all prepared for the drill. In real
emergencies, people are stupid and either don't know what to do (despite
all the safety lectures) or they do stupid things like trying to save
their laptops on the way out of the potentially burning or sinking
aircraft.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
  #24  
Old August 24th 18, 01:52 AM posted to sci.space.policy
Fred J. McCall[_3_]
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JF Mezei wrote on Thu, 23 Aug 2018
14:18:13 -0400:

On 2018-08-23 06:40, Jeff Findley wrote:

During crew ingress, the launch vehicle isn't at all fueled.


If this is a recent concession by NASA, it would explain why they still
needed those ziplines etc to be installed at a time where they thought
pad crews and flight crews would be present at a time the stack was
loaded with fuel and LOX.


Well, no. I thought they were a silly idea when they did them for the
Shuttle. They're sillier now.


I believe one of the goals of the ziplines is to get people away from a
burning rocket, something which an elevator doesn't do. *unless elevator
shaft is fire/bomb proof).


Rockets don't 'burn'. They detonate. You're never going to have time
to unbutton the capsule, jump in a basket, and zip line to safety.
Capsule, basket, and all will be in a big ball of fire.


In a new scenario where fueling is done after pad crew has left, the
odds or catastropy may be lower but not nill (consider structural
failure, premature start of loading of fuel in a sequencce that causes
explosion etc etc.


The zip line deal was never for 'pad crew'. It was and is for vehicle
crew.


NASA and SPaceX have measures in place to prevent known problems. The
issue is problems that have not been preducted. (look at the explosion
because of loading superxooled fuel in the wrong sequence with Helium)


Yes, look at that explosion and imagine trying to evacuate the capsule
and zip line to safety in the midst of all that.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
  #25  
Old August 24th 18, 11:53 AM posted to sci.space.policy
Fred J. McCall[_3_]
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JF Mezei wrote on Thu, 23 Aug 2018
23:21:38 -0400:

On 2018-08-23 20:52, Fred J. McCall wrote:

Rockets don't 'burn'. They detonate. You're never going to have time
to unbutton the capsule, jump in a basket, and zip line to safety.
Capsule, basket, and all will be in a big ball of fire.


It all depends on how far from the rocket the tower is and when
something happens whether the explosion is circumscribed mostly within a
certain diametre around the rocket (with "thust" going up instead of the
sides). And I would assume that the ET on shuttle would explode
differently than kerosene/LOX rockets.


If the tower is that far away, there's no need for ground crew to
escape and you just blew up most of your own argument.


One of the goals of those ziplines was to get people away from the
rocket, not just down. (and at bottom were either bunkers or tanks that
acted as bunkers)


Both, actually.


The whole zipline thing assumes people have some warning of thing before
they go kablooey. (or perhaps some fueling lines breaking so they evac
asap in case this catches on fire without necessarily involving whole
stack blowing up).


They might as well plan against meteor strike, as it's probably at
least as likely as that scenario.

The zip line deal was never for 'pad crew'. It was and is for vehicle
crew.


Sorry, but there was capacity for pad crew. Why would they be expandable
with no exit plan when astronauts had zipline ?


Sorry, but you need to provide a cite for that. Every description
I've seen very specifically says 'astronaut'.


In the case of Shuttle, since there was no capsule eject/jesttison, the
only means of emergency egress was via hatch and back to tower (assuming
bridge"/white room was still there)


Yeah. In the name of "we can't do anything that will matter so let's
do some theater".


With Dragon, having a capsule jettison capability changes things as this
becomes the safer means to quickly exit the area in case things go
kablooey.

But that still leaves pad crews with need for quick exit.


Which this system is not intended to provide.

Yes, look at that explosion and imagine trying to evacuate the capsule
and zip line to safety in the midst of all that.


If crews are strapped into capsule, and the problem is just some broken
O2 or kerosene pipe with no explosion yet, an evac for safety reason
would be different than an explosion where the only way out is to eject
capsule.


Why evac at all? Turn off the flow and shelter in place.


Also, if there is fuel leak without fire, you may not want to activate
elevator motors as potential sources of ignition. (not sure is seriosu
an issue this would be, but I ccould see a pedantic NASA insisting this
is a serious problem)


If there is a 'fuel leak without fire' (something I've NEVER heard of
happening with ANY rocket) you probably shouldn't be carrying people
(or expensive satellites) in the first place.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
  #26  
Old August 25th 18, 05:49 PM posted to sci.space.policy
Jeff Findley[_6_]
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In article ,
says...

Musk tweeted a picture of the crew access arm. It is very long.


No longer than the shuttle arm, because they're using the same fixed
structure on one side and the same flame trench on the other (so you'd
expect the Falcon launch vehicle to be on the same centerline as the
space shuttle).

So it would appear the tower will be at some distance from the rocket
itself.


Same as the shuttle.

Will be interesting to see how much of the "Shuttle" they are forced to
reproduce.


They're certainly reproducing much of the safety theater (as Fred called
it). Remember, this is the same NASA that initially thought shuttle
didn't need pressure suits on launch and landing and the same NASA that
didn't bother to even attempt to inspect the damage done to Columbia
while it was in orbit.

They're not especially good at putting "safety" in the right places, yet
they're "the experts" telling SpaceX and Boeing what to do. Cynical?
Yes, a bit. But, things that are different just aren't the same. Both
Dragon 2 and Starliner have zero-zero escape systems for the capsule
which shuttle obviously never had (shuttle had very large "dead zones"
where a significant failure *would* cause loss of crew.

For instance, the crew access arm for Shuttle could be brought back in
seconds to allow crews to egress in an emergency.


Seconds the crew wouldn't have if leaking hydrogen started burning. It
was a "feel good" measure put in place because there wasn't an escape
system on the shuttle.

Would this functionality be required or would the ability to jettison
capsule negate the need for "instant" emergency crew access arm rotation
back into position ?


Not sure what the sequencing will be. I'm sure SpaceX and NASA have it
all figured out.

One aspect to consider: in an aborted launch where something dubious
happened and they want emergency evac just in case, the crew access arm
and the zip lines (or even elevators) cause no damage to stack, do not
ignite anything. If it turns out to be a false alarm, they can releaunch
a day or two later after checks are done.


Then just sit in the capsule, just like one of the Gemini crews did when
the engines lit, then shut down. They should have ejected, by the
rules. But, they didn't feel the stack move, and ejecting carries its
own dangers, so they just sat there and waited it out. They made the
right call.

jettisoning the capsule at best destacks the rocket, at worse destroys
stage 2.


Better safe than sorry. Besides, you do know that Falcon 9 is a fairly
inexpensive to make, right? The pad is surely more valuable than the
Falcon 9 since any repairs on it delay the next flight.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
  #27  
Old August 26th 18, 03:30 AM posted to sci.space.policy
Fred J. McCall[_3_]
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JF Mezei wrote on Sat, 25 Aug 2018
10:54:14 -0400:


jettisoning the capsule at best destacks the rocket, at worse destroys
stage 2.


Hogwash. It removes the CARGO and destroys nothing. The capsule can
be replaced in less than a day.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
  #29  
Old August 26th 18, 11:04 PM posted to sci.space.policy
Fred J. McCall[_3_]
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JF Mezei wrote on Sun, 26 Aug 2018
11:39:51 -0400:

On 2018-08-26 08:59, Jeff Findley wrote:

Hogwash. It removes the CARGO and destroys nothing. The capsule can
be replaced in less than a day.


The way that the SuperDraco engines are canted, I suspect this is true.
They're angled *away* from the Falcon 9's upper stage. Surely the
initial boost would be straight up, which would protect the launch
vehicle from the exhaust.


So you agree with McCall that following emergency capsule jettison, the
stacks than be put back and launched in less than a day ?


Since they intend to be able to build a full stack and relaunch a
booster in a day, why would you think it would take any appreciable
time to mount a new capsule?


When jettisoning from launch pad, is there guidannce to bring capsule
down in salt water? or just blind "up, deploy parachutes and land
wherever" ?


It goes east (when launched on the east coast). Do you never bother
to learn ANYTHING before you ask stupid questions?


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson
  #30  
Old August 27th 18, 06:51 AM posted to sci.space.policy
Fred J. McCall[_3_]
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JF Mezei wrote on Sun, 26 Aug 2018
23:00:57 -0400:

On 2018-08-26 18:04, Fred J. McCall wrote:

It goes east (when launched on the east coast). Do you never bother
to learn ANYTHING before you ask stupid questions?


On the launch pad, it is pointing straight up. So a capsule being
jettisoned would go straight up, woudln't it?


So payloads get to orbit by going straight up? Uh, no.


So what sort of steering would it have (either with the rockets or with
parachutes) to direct it to water landing? or would it do a ground
landing for such an event ?


Again, do you never bother to learn ANYTHING before you ask stupid
questions? Super Dracos are throttleable, which means you can shape
the trajectory with them. Emergency escapes go for a parachute
landing in water. Everyone but you seems to know this.

"In August 2014, it was announced that the pad abort test would occur
in Florida, at SpaceX's leased pad at SLC-40, and the test was
conducted successfully on 6 May 2015. Dragon landed safely in the
ocean to the east of the launchpad 99 seconds later."

https://en.wikipedia.org/wiki/Dragon_2#Pad_abort_test


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson
 




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