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Two Point Suspension for Gemini Parachute



 
 
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  #1  
Old June 21st 05, 05:31 PM
John
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Default Two Point Suspension for Gemini Parachute

Here is another of those "how come" questions. What is the reason for
the two point suspension used to attach the main recovery parachute to
the Gemini spacecraft? I have googled and found descriptions of the
system but no rationale for this apparent added complexity.

Does anyone know what the anticipated consequences would have been if
the main chute deployed but did not shift from a single point to a two
point suspension? At first blush this doesnt seem to be a reason for
the crew to consider ejecting because if single point was good enough
for the first six (Mercury), seems it would sufficiently safe for a
Gemini crew.

Thank you in advance for any information that you might share.

blue skies

John

  #2  
Old June 21st 05, 10:30 PM
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John,

In a word: "Grissom". 8^ )

You may recall that Gus Grissom flew in one of the Mercury flights (I
believe it was the second). With the one point suspension holding up
the "pointy" end of his spacecraft, Gus apparently became concerned
that his craft was sinking when waves washed continually over his small
view window.
To get out, instead of waiting for the recovery crew as he was
supposed to do, he blew his hatch (window) and climbed out onto the
recovery inflated collar which was keeping it afloat and took off his
helmet.
Water began to wash into the craft (and into his space suit). The
spacecraft went to the bottom, and only by the grace of God, the
recovery helicopter was able to lift him with his suit also filled with
water, into the chopper for the ride back to the recovery carrier. Else
Gus would have been deep-sixed, as well.
You may recall that for his next flight, he named his craft "Molly
Brown" for the title character in the musical "The Unsinkable Molly
Brown", starring Debbie Reynolds. AAMOF, Debbie Reynolds sent Gus one
of her scarfs to carry onboard his Gemini flight.
NASA went to the two point suspension to keep the escape hatch "on
top" following an ocean landing, just to keep those spacecraft from
sinking. My memory is just a little bit fuzzy on all the details, but
I believe the two-point was a modification in the design AFTER Gus's
near-disaster. But, it MAY have been on the drawing boards even before
that happened.

I was a broadcast news reporter at the Cape, beginning with the last
Mercury flight and through Skylab, and as you know, that indeed IS
history!!!.

~ art

  #3  
Old June 21st 05, 11:02 PM
Pat Flannery
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Andre Lieven wrote:

Here is another of those "how come" questions. What is the reason for
the two point suspension used to attach the main recovery parachute to
the Gemini spacecraft? I have googled and found descriptions of the
system but no rationale for this apparent added complexity.


For starters, the twin hatches on the Gemini extended almost all the
way back to the heatshield, so if you impacted heatshield first, you
could have distorted the hatch frames enough that water could have
started to come in. Another reason was that Gemini was at one time
intended to land using an inflatable Parawing system, and that required
the crew to be in a horizontal position so they could steer it down and
land it on its skid landing gear:
http://www.ninfinger.org/~sven/model...i//parfl04.jpg

Does anyone know what the anticipated consequences would have been if
the main chute deployed but did not shift from a single point to a two
point suspension? At first blush this doesnt seem to be a reason for
the crew to consider ejecting because if single point was good enough
for the first six (Mercury), seems it would sufficiently safe for a
Gemini crew.


Assuming it did hit heat shield first- and kept floating that way,
you'd end up in a situation where the crew couldn't open the hatches
without flooding the spacecraft, as the bottom end of the hatches would
now be under water, that would mean unless the recovery crew could flip
it onto its side, so that it could right itself with the hatches on the
top, the crew would have to stay on board until it got hoisted onto the
recovery vessel.

Pat
  #4  
Old June 22nd 05, 01:58 AM
Rusty
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On 21 Jun 2005 09:31:11 -0700, "John" wrote:

Here is another of those "how come" questions. What is the reason for
the two point suspension used to attach the main recovery parachute to
the Gemini spacecraft? I have googled and found descriptions of the
system but no rationale for this apparent added complexity.

Does anyone know what the anticipated consequences would have been if
the main chute deployed but did not shift from a single point to a two
point suspension? At first blush this doesnt seem to be a reason for
the crew to consider ejecting because if single point was good enough
for the first six (Mercury), seems it would sufficiently safe for a
Gemini crew.

Thank you in advance for any information that you might share.

blue skies

John


The following NASA document gives one reason for the
two point suspension system used on Gemini.

Gemini spacecraft parachute landing system - Jul 1, 1966
http://ntrs.nasa.gov/archive/nasa/ca...1966020968.pdf


"...attenuation of the landing shock by positioning the spacecraft so
that it enters the water on the corner of the heat shield, thus
eliminating the need for built-in shock absorption equipment."


Rusty



  #5  
Old June 22nd 05, 02:06 AM
Matthew Ota
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Grissom "I did not blow the hatch!"...

Did he really do it?

I thought that they never determined how the pyros blew.

Matthew Ota

  #6  
Old June 22nd 05, 02:34 AM
Rusty
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On 21 Jun 2005 14:30:51 -0700, wrote:

John,

In a word: "Grissom". 8^ )

You may recall that Gus Grissom flew in one of the Mercury flights (I
believe it was the second). With the one point suspension holding up
the "pointy" end of his spacecraft, Gus apparently became concerned
that his craft was sinking when waves washed continually over his small
view window.
To get out, instead of waiting for the recovery crew as he was
supposed to do, he blew his hatch (window) and climbed out onto the
recovery inflated collar which was keeping it afloat and took off his
helmet.


1. Gus never at any time said he blew the hatch. He said he was
sitting there minding his own business and the hatch blew on its own.

2. An inflated recovery collar was never fitted to the Liberty Bell 7
by divers.

Water began to wash into the craft (and into his space suit). The
spacecraft went to the bottom, and only by the grace of God, the
recovery helicopter was able to lift him with his suit also filled with
water, into the chopper for the ride back to the recovery carrier. Else
Gus would have been deep-sixed, as well.
You may recall that for his next flight, he named his craft "Molly
Brown" for the title character in the musical "The Unsinkable Molly
Brown", starring Debbie Reynolds. AAMOF, Debbie Reynolds sent Gus one
of her scarfs to carry onboard his Gemini flight.
NASA went to the two point suspension to keep the escape hatch "on
top" following an ocean landing, just to keep those spacecraft from
sinking. My memory is just a little bit fuzzy on all the details, but
I believe the two-point was a modification in the design AFTER Gus's
near-disaster. But, it MAY have been on the drawing boards even before
that happened.


From the "Gemini Spacecraft Parachute Landing System" NASA Technical
Note - Jul 1, 1966

"The significant new concepts proven in the Gemini Program
for operational landing of a spacecraft include:
(1) the tandem pilot/drogue parachute method of deploying
a main landing parachute, and (2) attenuation
of the landing shock by positioning the spacecraft so
that it enters the water on the corner of the heat
shield, thus eliminating the need for built-in shock
absorption equipment."

"Two different types of spacecraft landing systems were considered in
the early phases of the Gemini Program. One was a parachute system
designed to land the reentry module in water, similar in concept to
the system used in Project Mercury. The other consisted of a
paraglider wing and landing gear to allow the reentry module to be
landed at a preselected airfield. Both designs underwent parallel
development. Hardware was procured, and development testing was begun
on both systems with the intent that the paraglider landing system
would be used on Gemini missions as soon as possible. However, as
testing progressed, it became apparent that the problems encountered
during the development of the paraglider could not be solved in time
to meet the Gemini flight schedules. Consequently, the parachute
system became the prime landing system planned for use on all Gemini
flights."


I was a broadcast news reporter at the Cape, beginning with the last
Mercury flight and through Skylab, and as you know, that indeed IS
history!!!.

~ art



Rusty
  #7  
Old June 22nd 05, 10:41 AM
Revision
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Grissom "I did not blow the hatch!"...
Did he really do it?
I thought that they never determined how the pyros blew.


It is undetermined. Grissom insisted that the hatch blew by itself. The
engineer insist that that is not possible. So my opinion is that a
person in a spacecraft that he thought was sinking might want to get out.

The two-point parachute attach was done in order to hold the spacecraft
at the proper angle to produce minimal Gs upon hitting the water.



  #8  
Old June 22nd 05, 03:13 PM
Henry Spencer
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In article . com,
John wrote:
Here is another of those "how come" questions. What is the reason for
the two point suspension used to attach the main recovery parachute to
the Gemini spacecraft?


The main reason was that Gemini's primary landing system was originally
the Rogallo-wing paraglider, which (a) required that the astronauts have a
forward view during landing, and (b) required horizontal touchdown on
landing gear. The ordinary parachute and water landing was first meant as
a stopgap until the paraglider was ready; only fairly late in development
did it become clear that the paraglider wasn't *going* to be ready.

The other, more minor, advantages could have been achieved in less drastic
ways -- e.g., for corner-first splashdown it would have sufficed to rig
the parachute suspension to bring the capsule down tilted, as indeed was
done for Apollo.

Does anyone know what the anticipated consequences would have been if
the main chute deployed but did not shift from a single point to a two
point suspension? At first blush this doesnt seem to be a reason for
the crew to consider ejecting because if single point was good enough
for the first six (Mercury), seems it would sufficiently safe for a
Gemini crew.


Remember that Mercury had an airbag for touchdown deceleration, which
Gemini lacked. However, provided you were coming down on water as
planned, that wasn't too important -- the Mercury airbag was mostly for
abort cases involving land touchdown. A Gemini splashdown flat on the
heatshield might have been a bit harsh, but probably not enough so to
justify an abort.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |
  #9  
Old June 22nd 05, 03:17 PM
Henry Spencer
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In article ,
Revision wrote:
Grissom "I did not blow the hatch!"...
Did he really do it?
I thought that they never determined how the pyros blew.


It is undetermined. Grissom insisted that the hatch blew by itself. The
engineer insist that that is not possible.


The engineers *originally* insisted that it was not possible, but a more
thorough later investigation found that there were a couple of ways in
which it could have happened.

Actuating the hatch-blowing system manually almost invariably resulted in
a conspicuous bruise on the astronaut's hand, which Grissom's hand lacked.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |
  #10  
Old June 22nd 05, 03:19 PM
Henry Spencer
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In article ,
Pat Flannery wrote:
Does anyone know what the anticipated consequences would have been if
the main chute deployed but did not shift from a single point to a two
point suspension? ...


Assuming it did hit heat shield first- and kept floating that way...


It was balanced to float hatches-up. The only question would be whether
the chute jettison system would still work after a failure in the
suspension changeover, but my guess is that it would have.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |
 




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