posted 01-05-2011 02:00 PM               

On that hatch there was a safety pin. It's kind of like the safety pin on a hand grenade. You know, you slip it out to enable the control to move. There was also, I think, a cover over the button that you used to explode the hatch. The hatch had this initiator in there, but what actually separated the hatch was a ring of Primacord that went all the way around the hatch. Then it was secured with a bunch of bolts that had been weakened by being [necked] down. The Primacord caused the bolts to fail, and so the hatch was really bolted in place and sealed. Then when you exploded the primer, which set off the Primacord, it blew the hatch off. There’d been some tests done, and the thing came off, a big bang, and it really blew the hatch a good distance.

So anyway, he had taken the cover off and pulled the safety pin preparatory to getting out. But there’s still, the way that thing’s configured, there’s a ring around that button, and it just doesn’t seem possible that he made contact with that. Certainly, based on his debrief, he certainly didn’t do it deliberately, and it’s hard to see how he could have possibly done it accidentally, because the way that button is down inside a ring, a cylindrical protector, you have to be very deliberate about it to make that thing go off.

posted 01-05-2011 09:43 PM               

There was a way of releasing the hatch from the outside.

To quote "The Project Mercury Familiarization Manual" section 2 page 7. "An exterior hatch release control is also provided to enable ground personnel to explode the hatch in the event the Astronaut is unable to do so."

It is my belief the line from the dyemarker snagged this external handle.

To also quote from the "Results of the Second U.S. Manned Suborbital Space Flight July 21,1961" page 55, "After I was in the water and away from the spacecraft, I noticed a line from the dyemarker can over my shoulder. The spacecraft was obviously sinking and I was concerned that I might be pulled down with it". - Virgil Grissom (Pilot's Flight Report).

Weather it was the line from the dyemarker canister, a strap from the landing bag or a parachute suspension line, we will never know.

posted 01-07-2011 08:28 AM               

The explosively actuated side hatch was used for the first time on the MR-4 flight. The mechanically operated side hatch on the MR-3 spacecraft was in the same location and of the same size but was considerably heavier (69 pounds rather than 23 pounds). The explosively actuated hatch utilizes an explosive charge to fracture the attaching bolts and thus separate the hatch from the spacecraft. Seventy 1/4-inch titanium bolts secure the hatch to the doorsill. A 0.06-inch diameter hole is drilled in each bolt to provide a weak point. A mild detonating fuse (MDF) is installed in a channel between an inner and outer seal around the periphery of the hatch. When the MDF is ignited, the resulting gas pressure between the inner and outer seal causes the bolts to fail in tension. The MDF is ignited by a manually operated igniter that requires an actuation force of around 5 pounds, after the removal of a safety pin. The igniter can be operated externally by an attached lanyard, in which case a force of at least 40 pounds is required in order to shear the safety pin.

There was a way of releasing the hatch from the outside. To quote "The Project Mercury Familiarization Manual" section 2 page 7. "An exterior hatch release control is also provided to enable ground personnel to explode the hatch in the event the Astronaut is unable to do so."

posted 01-07-2011 09:46 AM               

quote:

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Originally posted by space1:
Keep in mind that the section of the control panel to the right of the periscope could be removed (by pulling a lever). This allowed easier exiting through the side or nose hatches.

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posted 01-08-2011 08:48 AM               

Does this mean that the lanyard was already attached or does it mean the recovery crew had to attach it?

If the latter and remembering that Wayne Koons said that the hatch went a fair distance, how close was the person that yanked the lanyard?

posted 01-11-2011 12:24 PM               

quote:

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Originally posted by moorouge:
Were those blown hatches ever recovered?

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posted 03-29-2012 05:34 PM               

Escape systems are typically like that in aircraft, be they canopy jettison switches or the ejection seat handles. When they have to work the first time, cutting down the equipment to the bare minimum means the chances of success go up. Besides, a bruise and cuts on knuckles are tame compared to the potential alternative (which is one reason why Apollo's hatch was redesigned after Apollo 1, since they didn't have that direct escape method).

posted 03-29-2012 08:55 PM               

On page 55 of the of Results Of The Second U.S. Manned A Suborbital Space Flight July 21, 1961" - Pilot's Flight Report Grissom said he removed a survival knife from the hatch and removed the protective cap and safety pin from the hatch detonator.

The survival knife appears to be nearly one-foot long in pictures from the recovered Liberty Bell 7. See Figures 6a and 6b Page 7 here.

Grissom mentions the knife twice in the pilot's flight report. Once when he said he removed the knife from the hatch and stowed it in the survival kit. A second time when he said he thought about carrying the knife out with him as a souvenir.

And here's a diagram from the 1961 edition of the Mercury Familiarization Manual, PDF page 18. This shows where the survival knife and hatch release initiator are located on interior of the side hatch. Right next to each other.

Is it possible, in trying to maneuver this large knife in the confined capsule, tossing in the sea, he accidentally bumped the hatch detonator with the knife? Setting off the detonator in this manner would leave no mark on his hand like later Mercury astronauts received.

The knife was found loose in the bottom of the capsule. If it happened this way, maybe Grissom was too embarrassed to admit the hatch blew because of a souvenir.