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Author Topic:   Gemini spacecraft parachute deployment
Jim_Voce
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posted 06-14-2017 05:37 AM     Click Here to See the Profile for Jim_Voce   Click Here to Email Jim_Voce     Edit/Delete Message   Reply w/Quote
Does anyone know how the Gemini spacecraft parachute system worked?

In the Mercury Program, the spacecraft descended with the top of the spacecraft pointed directly upward. But the Gemini spacecraft did not. It descended at a skewed angle. This is because a cable of some kind seemed to slide down the length of the spacecraft and adjusted the parachute so that the spacecraft would land in the water on its side with the astronauts sitting straight up in their seats.

The parachute rigging of the Gemini spacecraft was created to support the deployment of the Rogallo Wing. And even though the Rogallo Wing was cancelled, the parachute rigging positioning was kept. But I still have no idea how the Gemini parachute rigging was was able to come out of the top of the spacecraft and secure itself to the side of the spacecraft.

Jim Behling
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From: Cape Canaveral, FL
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posted 06-14-2017 08:02 AM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
I could explain it but a simple google is just easier: Gemini Guide: Landing Systems.

Jim_Voce
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posted 06-15-2017 01:05 AM     Click Here to See the Profile for Jim_Voce   Click Here to Email Jim_Voce     Edit/Delete Message   Reply w/Quote
Thank you the link. I have seen similar diagrams.

What is not clear to me is how the so-called "two points of suspension system" of the Gemini parachute operated. In other words, how is it that the entire parachute system can deploy from the top of the spacecraft in what is described as a 'single point" of suspension (i.e., the parachute lines point straight up just as with the Mercury spacecraft) but then afterwards, one of the parachute suspension ropes is able to slide down the length of the Gemini spacecraft toward the heat shield and then create a two point suspension system where in the Gemini spacecraft lands in the water on its side rather than on its bottom (i.e., on its heatshield)?

Was there some kind of groove or channel carved into the side of the Gemini spacecraft that allowed one of the suspension lines to travel down the length of its body?

taneal1
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posted 06-15-2017 01:34 AM     Click Here to See the Profile for taneal1   Click Here to Email taneal1     Edit/Delete Message   Reply w/Quote
A channel, yes, not on the side, but between the crew hatches. That white "stripe" is actually just a piece of plastic covering the channel that houses a strap that is attached near the heat shield. The white plastic strip is ripped open by this suspension line when the spacecraft is released from single-point to two-point suspension. This causes quite a jolt within the spacecraft and has scratched or even punctured astronaut face plates.

Before switching to two-point suspension the astronauts use mirrors to assure they are over water. If they are over land, they must eject. You can't do that from the two-point position as the seats would hit the open chute.

Jim Behling
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From: Cape Canaveral, FL
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posted 06-15-2017 06:40 AM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Jim_Voce:
I have seen similar diagrams... Was there some kind of groove or channel carved into the side of the Gemini spacecraft that allowed one of the suspension lines to travel down the length of its body?
The very first diagram (Parachute Landing System Diagram) in the link shows the channel.

moorouge
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posted 06-15-2017 12:42 PM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
Perhaps this provides more detail — NASA Technical Note: Gemini Spacecraft Parachute Landing System.

sev8n
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From: Dallas TX USA
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posted 06-15-2017 06:13 PM     Click Here to See the Profile for sev8n     Edit/Delete Message   Reply w/Quote
At what point was the nose fairing jettisoned to expose the mortar/cable assemblies? The uncovered assemblies are visible in the 7/6 rendezvous photos, was the cover blown off during boost phase?

Jim_Voce
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posted 06-16-2017 04:08 AM     Click Here to See the Profile for Jim_Voce   Click Here to Email Jim_Voce     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by moorouge:
Perhaps this provides more detail...
Many thanks. The combination of taneal1's wonderfully concise and on point description along with your document was great.

Fra Mauro
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posted 06-16-2017 06:11 AM     Click Here to See the Profile for Fra Mauro   Click Here to Email Fra Mauro     Edit/Delete Message   Reply w/Quote
Is it safe to conclude that the Gemini spacecraft could not safely land in the water like Mercury since their was no air cushion bag attached to the heat shield?

Jim Behling
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From: Cape Canaveral, FL
Registered: Mar 2010

posted 06-16-2017 08:19 AM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
No, it could still land in the water without the two point suspension. The two point suspension made it softer.

space1
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From: Danville, Ohio
Registered: Dec 2002

posted 06-16-2017 11:29 AM     Click Here to See the Profile for space1   Click Here to Email space1     Edit/Delete Message   Reply w/Quote
The nose fairing and horizon scanner fairing were jettisoned about 10 minutes after launch (after second stage shutdown and before spacecraft separation) with astronaut activation of the JETT FAIRING pushbutton switch.

moorouge
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posted 06-16-2017 02:28 PM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Fra Mauro:
Is it safe to conclude that the Gemini spacecraft could not safely land in the water like Mercury since their was no air cushion bag attached to the heat shield?
The answer lies here does it not -
The significant new concepts that were 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 space-craft, thus eliminating the need for built-in shock absorption equipment.
Positioning meant that the capsule entered the water on a corner of the heat shield rather than with it flat as in Mercury.

Incidentally, the paper I referenced in my previous post also mentions that the ejector seats were only available with the drogue chute deployed. Once under the main chute and configured for landing, if used the ejector seats would foul the parachute.

One other significant difference was that there was no automatic parachute deployment on Gemini as was the case for Mercury. The sequence had to be initiated by the pilot.

taneal1
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From: Orlando, FL
Registered: Feb 2004

posted 06-17-2017 12:05 AM     Click Here to See the Profile for taneal1   Click Here to Email taneal1     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by moorouge:
...the paper I referenced in my previous post also mentions that the ejector seats were only available with the drogue chute deployed.
I just did a quick read of that document, and I can't find a statement that the seats are only usable on the drogue chute.

You stated: "Once under the main chute and configured for landing, if used the ejector seats would foul the parachute." Doesn't "configured for landing" mean in the two-point suspension mode?

In the single-point mode the spacecraft is vertical. Even with the somewhat upward vector the seat would clear the deployed chute. As I stated in my last post, ejection is possible from the single-point mode, but not from the 2-point.

I'm always willing to accept new information, but this is what I recall.

Lou Chinal
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Registered: Jun 2007

posted 06-17-2017 01:10 PM     Click Here to See the Profile for Lou Chinal   Click Here to Email Lou Chinal     Edit/Delete Message   Reply w/Quote
I have to agree with taneal1.

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