LEM crew interior.

[hellblazer]

Alright I got a question for you in two folds.

1- How thick was the interior and exterior walls in total?

2- what was the interior LEM size? hight width depth.

[Bob B.]

Aug 2, 2010 10:00:47 GMT -4 hellblazer said:

1- How thick was the interior and exterior walls in total?

I don't have those figures at hand, but below is a illustration showing the basic construction of the hull and micrometeoroid protection.

Aug 2, 2010 10:00:47 GMT -4 hellblazer said:

2- what was the interior LEM size? hight width depth.

The data I have says the crew compartment was 2.35 meters in diameter by 1.07 meters long with a habitable volume of 4.5 m³. I think this a just the front section of the LM where the astronauts stood during descent/ascent. There is also the area above the ascent engine, which I don't have figures for.

[echnaton]

Welcome to the board, hellblazer.

I don't have a specific answer for your query, but the thickness of the pressure vessel varied. Panels were produced at a certain thickness, then chemically milled to reduce thickness in specific ways to minimize weight while maintaining the needed structural properties. So at a certain level of precision, there is no one answer.

To fill a deeper interest in the Lunar Module you may find this book interesting.

Virtual LM: A Pictorial Essay of the Engineering and Construction of the Apollo Lunar Module

[lukepemberton]

Aug 2, 2010 10:40:51 GMT -4 Bob B. said:

I don't have those figures at hand, but below is a illustration showing the basic construction of the hull and micrometeoroid protection.

Thanks for the interesting image of the LM's micrometeoroid shield.

I have read somewhere before how a micrometeroid shield works, and that fits exactly what I have read. It breaks up's the intial particle into smaller fragments, which are then stopped by subsequent layers. Does the construction technique of such layers, or the mechanism by which the micrometeoroid is broken up and stopped have a name(s).

[Bob B.]

Aug 2, 2010 11:15:29 GMT -4 lukepemberton said:

I have read somewhere before how a micrometeroid shield works, and that fits exactly what I have read. It breaks up's the intial particle into smaller fragments, which are then stopped by subsequent layers. Does the construction technique of such layers, or the mechanism by which the micrometeoroid is broken up and stopped have a name(s).

I'm not sure if it has a name or not; however, the technique was not new to Apollo. Many warships used the same technique to protect against torpedoes, shells and bombs. For instance, a battleship's deck many have a thin upper deck that causes a plunging shell or bomb to explode and then a second armor deck to protect against the shrapnel from the exploded bomb.

[Ginnie]

Aug 2, 2010 10:57:31 GMT -4 echnaton said:

Welcome to the board, hellblazer.

I don't have a specific answer for your query, but the thickness of the pressure vessel varied. Panels were produced at a certain thickness, then chemically milled to reduce thickness in specific ways to minimize weight while maintaining the needed structural properties. So at a certain level of precision, there is no one answer.

To fill a deeper interest in the Lunar Module you may find this book interesting.

Virtual LM: A Pictorial Essay of the Engineering and Construction of the Apollo Lunar Module

I just happened to have checked that book from the library on Saturday. Excellent illustrations. I want to buy it and Virtual Apollo.
Anyway, here is a scan of the Thermal blanket that was used on the LM.
It did vary in thickness depending on where it was located.
(from the book "Virtual LM" page 193)

(picture removed by ginnie as may be violating copyright)

[hellblazer]

alright great info. If someone had the total inner sizer of the crew compartment that would also be great.

[ka9q]

Aug 2, 2010 11:15:29 GMT -4 lukepemberton said:

Does the construction technique of such layers, or the mechanism by which the micrometeoroid is broken up and stopped have a name(s).

I think it's known as a Whipple Shield.

[lukepemberton]

Aug 2, 2010 23:23:09 GMT -4 ka9q said:

I think it's known as a Whipple Shield.

That's the one. A Whipple shield... thanks! Sorry if my question to Bob was not clear.

Interestingly, the first tanks of World War 1 eventually adopted a similar design. At first their hulls were made of a single sheet of metal. Any bullets hitting the outside caused fragments of steel to be ejected on the inside (due to shock waves), causing the occupants to be injured. Not that it mattered, as they were overcome by carbon monoxide from the engines anyway. Future tank hulls were made of layers (I think two) so the second layer would absorb the ejected fragments. Most modern armour works on this principle.

[Kiwi]

Aug 2, 2010 10:00:47 GMT -4 hellblazer said:

...what was the interior LEM size? hight width depth.

The habitable portion of the lunar module crew compartment was a complex shape, nothing like cuboid, so there are no simple height, width and depth measurements. You may find a rough overall measurement, but if you want accurate figures you will probably have to do considerable research to find multiple measurements, perhaps starting with the Virtual LM book mentioned above. None of my Apollo books seem to mention the size of the crew compartment.

Please note the correct abbreviation of LM for lunar module. Many hoax-promoters use the abbreviaton LEM which shows just how much they know. The word excursion was dropped from the name long before it flew, perhaps because some bright spark realised that the LM wasn't going to do any excurdging on the lunar surface. The pronuciation of "lem" stayed though, obviously because its a single syllable, just as PGNCS for primary guidance and navigation control system became "pings."

The following from the Apollo 11 Press Kit has a few details:

Ascent Stage

Three main sections make up the ascent stage: the crew compartment, midsection, and aft equipment bay. Only the crew compartment and midsection are pressurized (4.8 psig; 337.4 gm/sq cm) as part of the LM cabin; all other sections of the LM are unpressurized. The cabin volume is 235 cubic feet (6.7 cubic meters). The ascent stage measures 12 feet 4 inches high by 14 feet 1 inch in diameter.

Structurally, the ascent stage has six substructural areas: crew compartment, midsection, aft equipment bay, thrust chamber assembly cluster supports, antenna supports and thermal and micrometeorold shield.

The cylindrical crew compartment is a semimonocoque structure of machined longerons and fusion-welded aluminum sheet and is 92 inches (2.35 m) in diameter and 42 inches (1.07 m) deep. Two flight stations are equipped with control and display panels, armrests, body restraints, landing aids, two front windows, an overhead docking window, and an alignment optical telescope in the center between the two flight stations. The habitable volume is 160 cubic feet.

Two triangular front windows and the 32-inch (0.81 m) square inward-opening forward hatch are in the crew compartment front face.

External structural beams support the crew compartment and serve to support the lower interstage mounts at their lower ends. Ring-stiffened semimonocoque construction is employed in the midsection, with chem-milled aluminum skin over fusion-welded longerons and stiffeners. Fore-and-aft beams across the top of the midsection join with those running across the top of the cabin to take all ascent stage stress loads and, in effect, isolate the cabin from stresses.

The ascent stage engine compartment is formed by two beams running across the lower midsection deck and mated to the fore and aft bulkheads. Systems located in the midsection include the LM guidance computer, the power and servo assembly, ascent engine propellant tanks, RCS propellant tanks, the environmental control system, and the waste management section.

A tunnel ring atop the ascent stage meshes with the command module docking latch assemblies. During docking, the CM docking ring and latches are aligned by the LM drogue and the CSM probe.

The docking tunnel extends downward in to the midsection 16 inches (40 cm). The tunnel is 32 inches (0.81 cm) in diameter and is used for crew transfer between the CSM and LM. The upper hatch on the inboard end of the docking tunnel hinges downward and cannot be opened with the LM pressurized and undocked.

A thermal and micrometeoroid shield of multiple layers of mylar and a single thickness of thin aluminum skin encases the entire ascent stage structure.

[Obviousman]

This may also help illustrate why there are no simple dimensions:

www.ehartwell.com/LM/SCATSystems.htm

www.ehartwell.com/LM/SCATPhotos.htm

www.ehartwell.com/LM/SCATCloseLook.htm

[echnaton]

The US M1 tank armor has multiple layers of differing materials as well, with spaces in between. The space provides a route to channel pressure waves from impacts outside the armor and dissipate heat through convection.