posted 05-02-2017 07:49 AM               

Does anyone know how many Mercury hatches were recovered? I know Liberty Bell 7's is at the bottom of the Atlantic and that Aurora 7's should have been retained since Carpenter exited via the neck hatch.

posted 05-03-2017 01:34 AM               

But I believe he also had a way of opening the hatch from the inside. In fact, the mission report for the MR-4 flight noted that Shepard's MR-3 had a "mechanically operated" side hatch.

posted 05-03-2017 07:42 AM               

quote:

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Originally posted by Jim_Voce:
And back to the original question, why did Grissom want a hatch with explosive bolts?

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posted 05-03-2017 10:51 AM               

Among other innovations in No. 11 for MR-4 was an explosive side hatch, whose evolution, encouraged by the astronaut corps, had begun early in the Mercury program. The original egress procedure had been to climb out through the antenna compartment,a difficult maneuver that required the removal of a small pressure bulkhead. Since all the astronauts had found it hard to snake out the top of the frustum and cylinder, the STG and McDonnell designers had concluded that removal of an injured astronaut would be even more precarious. Moreover, valuable time would be lost in such a rescue [367] operation; to open the hatch from the outside, someone had to remove several shingles and 70 bolts.

McDonnell engineers set to work on the problem and came up with two egress hatch models - one with a latch, which was used on Ham's MR-2 and Shepard's MR-3 missions, the other with an explosive hatch cover. The simple latch mechanism weighed 69 pounds, too much of a weight addition for incorporation in the orbital version of the spacecraft. The explosive hatch, on the other hand, utilized the 70 bolts of the original design; a .06-inch hole was bored into each of the quarter-inch titanium bolts to provide a weak point. When a mild detonating fuse, placed in a groove around each bolt, was energized, the bolts were sheared simultaneously and the hatch sprang open.

There were two ways to activate the explosive egress hatch during recovery. About six to eight inches from the astronaut's right arm, as he lay in his couch, was a knobbed plunger. The pilot would remove a pin and press the plunger with a fist-force of five or six pounds, detonating the small explosive charge and blasting the hatch 25 feet away in a second. If the pin was in place, a fist-force of 40 pounds was required. A rescuer outside the capsule could blow open the hatch simply by removing a small panel from the fuselage side and pulling a lanyard. This complete explosive hatch weighed only 23 pounds.

posted 05-03-2017 11:16 AM               

quote:

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Originally posted by Jim_Voce:
...why did Grissom want a hatch with explosive bolts?

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The astronauts had lobbied for an explosive hatch that operated much like an airplane canopy blowing off when a pilot ejected from an aircraft. Liberty Bell 7's twenty-three-pound escape hatch was much lighter than the mechanically operated side hatch flown on Shepard's mission.

...In the months before his flight, Grissom observed tests of the new exploding hatch designed by Honeywell to give Mercury pilots a quick exit in an emergency. NASA film footage shows Grissom inspecting the hatch on a test stand just before it was detonated. The pilot can be seen questioning test engineers while inspecting one of the titanium bolts. Everyone seemed satisfied the device would work.

posted 05-03-2017 09:09 PM               

quote:

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Originally posted by Headshot:
Does anyone know how many Mercury hatches were recovered?

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Grissom's hatch of course is on the bottom near the recovery site of his spacecraft.

On board the destroyer Noa, Glenn began the process of exiting through the top hatch, but decided instead to blow his hatch. Schirra and Cooper blew their hatches while on board their recovery carriers.

Carpenter exited via the top hatch and his hatch remained in place on the spacecraft.

Of the six hatches, two are on the bottom of the Atlantic, and two are in NASA's custody.

posted 05-04-2017 07:35 PM            

I must have read about the blown hatch on MR-4 a thousand times and in almost every account the issue of the "plunger recoil" comes up. To me "recoil" means "kickback" (i.e. shotgun). In the context of the defense of Grissom's position that he could not have accidentally hit the hatch plunger it is mentioned that those that deliberately hit the plunger were left with a bruise on their hand from the "recoil" — a bruise that Grissom apparently did not have.

posted 05-05-2017 08:31 AM               

If the plunger recoil was so violent, why would not the astronaut keep his right glove on to protect his knuckles if he was going to blow the hatch?

posted 05-06-2017 08:51 AM            

quote:

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Originally posted by Headshot:
Is there similar trauma on any images of Schirra or Cooper after they exited their spacecraft?

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posted 05-06-2017 10:08 AM               

quote:

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Originally posted by Paul78zephyr:
I understand the need to make the hatch blow apparatus 'accident proof' but it would seem to me there are a lot of ways to do that without resorting to a design that injures the user in an emergency.

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posted 12-29-2019 04:38 PM               

Only two mechanical hatches existed as far as I have been able to determine. As planned, Shepard allowed his to fall into the ocean when he released it, and according to the Smithsonian, Ham's hatch is in storage at the Dulles Annex.