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Author Topic:   Gemini ejection system hardware components
taneal1
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Posts: 230
From: Orlando, FL
Registered: Feb 2004

posted 05-22-2017 03:17 PM     Click Here to See the Profile for taneal1   Click Here to Email taneal1     Edit/Delete Message   Reply w/Quote
The Gemini spacecraft ejection process begins when either astronaut pulls the D-ring located between his knees. This action ignites a length of MDF (Mild Detonating Fuse) which produces an increasing pressure inside the Hatch Actuator mechanism. This pressure extends a "Latch Piston" (located at the base of this actuator) "which unlocks the hatch through a bellcrank/pushrod mechanism" (quote from the Gemini Familiarization Manual).

A line drawing in the manual depicts a bellcrank and several inches of the pushrod. No mention is made as to where/how this pushrod connects to the latching mechanism on the inside of the hatch.

Does anyone know the location of this pushrod and how it connects to the hatch latching mechanism?

space1
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Posts: 853
From: Danville, Ohio
Registered: Dec 2002

posted 05-22-2017 08:58 PM     Click Here to See the Profile for space1   Click Here to Email space1     Edit/Delete Message   Reply w/Quote
The pushrod is located below the ejection seat rails. It does not connect directly to the hatch, but hits a "striker" of the "aft tripper crank" of the latch mechanism. This mechanically drives the latches to the unlocked position. The image below shows this portion of the mechanism (looking outward from the inside of the left hatch). The aft tripper crank is at the lower right, with links to the latch mechanism. (Four of the 12 latches are seen at bottom and left.)

The latch mechanism may also be driven by the astronaut using a latch handle. But first the handle must be set for locking or unlocking the mechanism. A placard next to this handle cautions that the handle must stow in the neutral position. If the handle were not set to neutral when an abort was initiated, the gears would jam and the hatch would not open.

The image was made from this digital model based on McDonnell Aircraft drawings.

taneal1
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Posts: 230
From: Orlando, FL
Registered: Feb 2004

posted 05-23-2017 01:21 AM     Click Here to See the Profile for taneal1   Click Here to Email taneal1     Edit/Delete Message   Reply w/Quote
Thanks for the Solidworks model image.

Is this the pushrod from the Hatch Actuator Latch Piston that hits the "Striker" which unlatches the hatch?

space1
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Posts: 853
From: Danville, Ohio
Registered: Dec 2002

posted 05-23-2017 05:15 AM     Click Here to See the Profile for space1   Click Here to Email space1     Edit/Delete Message   Reply w/Quote
Yes, that is correct.

taneal1
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Posts: 230
From: Orlando, FL
Registered: Feb 2004

posted 05-23-2017 09:29 AM     Click Here to See the Profile for taneal1   Click Here to Email taneal1     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by space1:
The latch mechanism may also be driven by the astronaut using a latch handle. But first the handle must be set for locking or unlocking the mechanism.
The Fam Manual is sparse on details for this operation. It does indicate that the "Drive" and "Gain" selectors must be in "Neutral" to stow the hatch handle, but doesn't name the other possible selections. I presume they are "Lock" and "Unlock." Is this correct?

space1
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Posts: 853
From: Danville, Ohio
Registered: Dec 2002

posted 05-23-2017 09:35 AM     Click Here to See the Profile for space1   Click Here to Email space1     Edit/Delete Message   Reply w/Quote
Yes, the positions are lock and unlock. The positions are marked "L" and "U". Neutral is marked (you'll never guess...) "N".

taneal1
Member

Posts: 230
From: Orlando, FL
Registered: Feb 2004

posted 05-23-2017 06:08 PM     Click Here to See the Profile for taneal1   Click Here to Email taneal1     Edit/Delete Message   Reply w/Quote
Aww... I wanted to guess — now I'll never know if I would have gotten it right.

I've pulled my D-ring, the hatches are open and locked, the ballistic hose has delivered hot gas from the hatch actuator to the rocket-catapult, and... now I have to read what happens next. Back to the books!

All times are CT (US)

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