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Destination Moon (1950)
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Bud Brewster
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PostPosted: Sun Jun 03, 2018 1:03 pm    Post subject: Reply with quote

________________________________

That's some fine analytical thinking, Wayne! Very Happy

It just occurred to me that the pictures I posted above show the ship turning into landing position, and since we don't see any attitude jets firing, the turn was being done by those gyroscopes.

We also hear the same noise (the whirring of an electric motor ) during the turn and during the few seconds between General Thayer saying, "Jacks down," and then "Jacks are down. Cut out your gyros," — after which the sound stops.

(I'm probably wrong about him calling the fold-down strut "jacks". Listen the line on the YouTube video and see what you guys thing.)

This morning I was thinking about the whole matter of lightening the ship so that they would have enough fuel to get home. Obviously the ship need more than just enough fuel to lift off from the Moon, it also needed enough fuel to decelerate as it approached Earth — otherwise it would enter the atmosphere too fast and burn up!

We were mislead about this important fact by a conversation Dr. Cargraves and Joe have when the doctor says that if they don't lighten the ship enough, it will crash back into the Moon or go into orbit around it forever.

He doesn't mention the other danger, the need to decelerate after the ship literally falls 238,900 miles as it approaches Earth, picking up speed all the way, like every falling object does! Shocked

But the real epiphany came to me when I realized all three of us had missed the obvious when we debated whether the Luna would land tail first or try to glide like an airplane whose wings have been removed!

"One of Hollywood's best known actors" is a guest star in the movie, and he explains exactly how the ship would be designed to land when it got back to Earth. It will do it the same way all the NASA missions landed before the shuttle program began!

Like this.



________


We all forgot about the Woody Woodpecker cartoon that illustrated all the major aspects of the Moon mission, including the landing — which accurately predicted the use of parachutes for every returning NASA space craft from Mercury to Apollo.


]


So, mystery solved! The Luna did NOT need to have fuel to land tail first on Earth, nor did it need to land on its belly. Very Happy
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Gord Green
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PostPosted: Sun Jun 03, 2018 1:49 pm    Post subject: Reply with quote

Bud wrote:
He doesn't mention the other danger, the need to decelerate after the ship literally falls 238,900 miles as it approaches Earth, picking up speed all the way, like every falling object does!

You have touched on an interesting point.
Generally there is the aspect of TERMINAL VELOCITY, that is the greatest speed an object may reach when falling.

However, it's slightly trickier than that. "Terminal velocity" refers to the velocity something will reach under the influence of gravity and an atmosphere. While there is no atmosphere in the vacuum, it's also a bit odd to talk about terminal velocity in the abstract without talking about what's causing the gravity.

Gravity will cause you to fall until you hit the gravitating object. Unless you miss the gravitating object, in which case you will go into an elliptical orbit. You can accelerate towards it from a great distance, accelerating the whole time, but since the gravity is weaker from a distance, you will only accumulate so much total speed.

That limit is identical to the escape velocity: it's the amount of velocity you'd need to continue to move no matter how long gravity acted on you. You'd go farther and farther away, and gravity would get weaker and weaker, so that your speed would never reach zero.

So no, there's no terminal velocity, but that's not the same as saying you accelerate forever. You accelerate until you either hit the object, or pass it. Then you'll be begin to decelerate.

However it may land, and I agree with the parachute method (Perhaps augmented by rocket bursts like with the Soyuz capsule) it would still need enough fuel to offset the gravitation of the Moon and make course and speed adjustments to return to the Earth.

Good observation Bud!

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Bud Brewster
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PostPosted: Sun Jun 03, 2018 2:45 pm    Post subject: Reply with quote

________________________________

"Blessed are the peace makers . . . for they find the third alternative that wins the debate without pissin' anybody off." Cool

~ 1 Brewster: chapter 2, verse 12


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Krel
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PostPosted: Sun Jun 03, 2018 2:49 pm    Post subject: Reply with quote

The gyros got me thinking about all the 1950s and early 60s space travel books I read back in the 60s. I don't remember reading about the spaceships having vernier rockets for maneuvering. The ships always used gyros, they even made of point of it.

Considering the size of the Luna, it must have packed some HUGE parachutes in it's nose to make a soft landing. Laughing

The thing is, if the Luna was intended to make a four-point landing on Earth, a retractable strut makes no sense. If he strut was fixed, then they would have saved a lot of weight and complexity by doing away with the machinery for extending and retracting the strut. It would have been safer too.

I really need to watch D.M. again.

David.
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Bud Brewster
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PostPosted: Sun Jun 03, 2018 6:24 pm    Post subject: Reply with quote

Krel wrote:
The thing is, if the Luna was intended to make a four-point landing on Earth, a retractable strut makes no sense. If he strut was fixed, then they would have saved a lot of weight and complexity by doing away with the machinery for extending and retracting the strut. It would have been safer too.

Good points! Surely a fourth fin wouldn't have weighed much more than the retractable strut and all the machinery that went with it!

And I think we all agree that landing on the rough surface of the Moon on a three-finned rocket and hoping your gyros won't let the ship tip over before that silly strut is down is NOT good design!
Shocked
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Gord Green
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PostPosted: Sun Jun 03, 2018 7:13 pm    Post subject: Reply with quote

While these may not all be exactly canon, they clearly show that "gyro controlled fourth leg"
Anyway, just enjoy the specs!

NOTE: The parachute is clearly specified in the second schematic.
















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Krel
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PostPosted: Tue Jun 05, 2018 11:07 pm    Post subject: Reply with quote

Has anyone ever seen a photograph of the strut side of the Luna filming miniature? I'm just curious at how the strut fit into the miniature, did it just plug into the model?

David.
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Bud Brewster
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PostPosted: Wed Jun 06, 2018 9:27 am    Post subject: Reply with quote

________________________________

By gum, Krel, you bring up and interesting point. Actually we never see the strut on the miniature in any scene, deployed or otherwise!

We see the strut on the full-size prop of the rocket's base when it's on Earth and on the Moon, but never on the miniature at any time.

So, the model probably doesn't have the strut at all, even folded up.

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orzel-w
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PostPosted: Wed Jun 06, 2018 1:37 pm    Post subject: Reply with quote

I see a strut.




In the second image I even see the strut's shadow on the ground.
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Bud Brewster
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PostPosted: Wed Jun 06, 2018 2:02 pm    Post subject: Reply with quote

________________________________

Ah-ha! I'd forgotten about those shots! Thanks, Hawkeye!

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orzel-w
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PostPosted: Wed Jun 06, 2018 10:43 pm    Post subject: Reply with quote

I received my DVD today and watched DM. There are actually a number of scenes showing the strut on the miniature, one of which is this:



We know this is the miniature by several "tells". Compare it with the corresponding live action set:



The first tip-off was the movement of the figures. It was slightly jerky; typical of stop-motion animation. (Animated figures in space suits had also been used in some long shots of them walking on the hull of the ship during flight.)

More differences observed in the miniature:
The shadows cast by the figures are much darker.
The exhaust-scorched spot is relatively smaller and darker.
The helmets are darker gray and the air tanks are blue.
The boots are relatively larger and ankles are thicker. There is also a reflective highlight from the red boot. The costume boots are non-reflective.
The helmet collars are not as high.
The fifth ladder rung up is even with the bottom of the fin where it joins the hull. The fifth rung of the full size set sits well above that point.

I have no idea why they used miniatures for the first shot above, unless they had wrapped the live filming, struck the sets and discovered too late that they needed a shot of the two characters stepping off the ladder.

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Eadie
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PostPosted: Thu Jun 07, 2018 12:22 pm    Post subject: Reply with quote

Could it be just to give Walter Lance a small part in the making of the movie?
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Bud Brewster
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PostPosted: Thu Jun 07, 2018 5:01 pm    Post subject: Reply with quote

________________________________

I'm perplexed.

The shot shown in the first screen grab (which is at the 1:09:07 mark on the YouTube version) is barely two seconds long, and as your other screen grab shows, it could easily have been shot with the actors on the full sized set.

Why did they bother to make that brief two-second animation shot of Jim Barnes and General Thayer coming down to join Cargraves and Joe when they could have just had the actors do the same thing at ladder in the shot shown in your second picture and then walk over to join the other two men?

Did they have to created a detailed section of the lunar surface just for that shot? Is that the same miniature of the rocket we see in the scene at the factory, or is it a larger miniature of the base only, with the rungs of the ladder added? How small are those incredibly detailed animation models and that miniature of the same telescope we see in the live action shot?

Wayne, in all the years I've been watching this movie, I never noticed that stop motion shot. Thanks again, Hawkeye! Very Happy

I looked at the EVA scenes that were done with animation, and we never get a close enough shot of the figures to judge the amount of detail they contained, but the brief scene on the Moon certainly proves that they were not simple models.

And while looking at the EVA scenes, I noticed a few things I'd missed prior to this. For example, for some strange reason Cargraves borrows Joe's rope when he goes back to inspect the stern tubes.






He attaches it to the hull, and walks to the rear of the ship while Joe and Barnes begin working on the stuck antennae.





Cargraves leans over the stern of the ship and floats off directly behind it.





Why Cargraves chose to use Joe's rope instead of his own is puzzling — especially in view of the fact that he unhooked the borrowed rope from his suit and left it floating a few feet behind him when he foolishly knelt down to look over the edge of the ship and inspect the stern tubes!

Why didn't Mr. Rocket Scientist take off his own rope, hook it to Joe's, and THEN try to inspect the stern tubes? Shocked

When Cargraves hollers for help, we see Joe working on the stuck antennae with one magnetized boot flat on the hull to hold him down and one knee on the hull next to it. Barnes is gripping a rope that's hooked to the hull (off to our right), and the end of that rope is hooked to Joe's belt for a safety.






But the question is . . . where did THAT rope come from? Shocked

Barnes still has his rope attached his thigh, and Joe loaned his rope to Cargraves, even though he didn't need it. When Joe and Barnes make their way back along the hull to get close to Cargraves, they bring that rope with them and throw it to the drifting man.

Where did they get that FOURTH ROPE?

Another puzzling thing I noticed is the sudden change in Cargraves position relative to the ship. When the other two men arrive at the closest point to Cargraves, he's now positioned not far from the midway point of the ship. Instead of drifting further away from the stern of the ship, Cargraves seems to be floating past it in the direction of the nose!






Barnes tries to toss the end of the end of the mysterious fourth rope to Cargraves, but it stops short, less than a foot from his hand — although Cargraves didn't really know that, because his helmet prevented him from seeing the rope!





And that's mighty odd, because right before Barnes throws the rope, we see a view looking over Cargraves' shoulder back at the Luna, and positioned almost heads-up and feet-down relative to the guys standing on the hull!





With that in mind, why did they make the poor actor hang from his harness above the sound stage floor face-down. Wouldn't it have made more sense to hang him feet-down so the shot from behind him looking towards the Luna would have matched the shots of the guys looking out at Cargraves?

If they'd done that, the scene would have looked something like this. Very Happy






That way the poor guy could actually see the end of the rope when he says, "I can't reach it!"

And then the scene would have looked like this. Wink






But what really bothers me in this whole scene is the fact that Barnes should have quickly hooked his own rope to the mysterious fourth rope and tossed the double-length rope to Cargraves! Shocked

However, neither Joe nor Barnes thought to hook the two ropes together either, so Barnes tells General Thayer to bring out an oxygen bottle. Inside the airlock we see General Thayer struggle to lift the heavy oxygen bottle . . . which is obviously NOT weightless like it should be! (Oops.) Embarassed






When he joins Joe and Barnes on the hull, we can see that Cargraves has floated further away from the ship.





That probably means that the two-rope strategy would no longer work. Smile

But wait! General Thayer not only brought the oxygen bottle (staggering visibly under the weight of it as he joined the other guys), he also brought his own rope! That means they now have THREE ropes. So, perhaps they still didn't need the oxygen bottle to get Cargraves back.






However, nobody thinks of this either, so Barnes straddles the oxygen bottle and sends out a blast which immediately propels him . . . into a spin, because the jet of oxygen is much higher than his center of gravity! Shocked

Wait, no, that doesn't happen because the whole heroic idea wouldn't work if we stuck too close to the laws of physics. So, Barnes skillfully rides the worlds first "oxygen bottle rocket"* into space to rescue Cargraves and bring him safely back to the ship.






Gentlemen, I love this movie. But the EVA rescue scene is riddled with puzzling misjudgements, glaring errors in continuity, faulty portrayals of zero-gravity, and plain old bad science.

* For the record, the Luna is actually just a giant "water bottle rocket", because it uses super-heated water as its reaction mass. Cool

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Krel
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PostPosted: Thu Jun 07, 2018 6:47 pm    Post subject: Reply with quote

The original plan was to use a shotgun for the rescue, they figured that most of the audience would know about the kickback of a shotgun. They dropped that plan when they couldn't figure out a plausible reason to have a shotgun on the Luna.

David.
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orzel-w
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PostPosted: Thu Jun 07, 2018 7:01 pm    Post subject: Reply with quote

I gave up trying to follow the rationale of the movie's lifeline shtick. I chalked it up to an excuse to show something more visual, i.e., the oxygen bottle rocket.

Incidentally, the DVD I bought was a 50th Anniversary Edition. While the color and image quality were good, the print they used for the transfer wasn't in prime condition. It had dirt specks, splices, and other artifacts of use and handling. This movie deserves a restoration.

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