Comments by "ke6gwf - Ben Blackburn" (@ke6gwf) on "Scott Manley"
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@guidedmeditation2396 you are correct that NASA used experienced seamstresses to sew the gloves and fine details on the Apollo suits, and some of them were probably grandmothers, but the key was that they were the best seamstresses around, hired out of the garment industry because there was no aerospace industry at the time, and able to make the perfectly fitted suits accurately.
But you have to remember that the suits had many layers of different materials, for comfort against the skin, insulation, debris protection, ventilation, bellows for mobility, etc, and then they had a pressure layer over the top of it.
In addition, are you unaware that you can seam seal stitches?
Between stitching through wet sealant, applying flexible sealants over the top of the stitches, applying seam sealant tapes over the seams, dipping the entire thing in liquid latex, etc etc, there are countless ways to seal needle holes and prevent leaks.
And the Apollo suits didn't function flawlessly for a long period of time, they were each used once and then replaced.
No Apollo suit went to the moon twice, because they wore out too fast.
The part that you don't seem to understand is that while the seamstresses may have been sewing the suits together, the materials they were using were all custom designed and manufactured by teams across the country developing and testing new materials, and then after the ladies would sew a suit up, it would be sent to a giant lab and extensive testing done on it.
Then the life support systems would have to be designed and built and tested, because these aren't just some fancy set of pajamas they are sewing up, it's a self contained miniature space ship, and the ladies were only responsible for assembling the soft parts of it, not building the entire thing.
So if you think that they could build another one by getting done grannies in a sewing circle, you are missing the thousands of workers in labs and factories across the country that it took to make each suit, and so don't understand how expensive the Apollo suits were, or why new ones are so expensive.
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jeff deathrage hi! Ham Radio operator here.
We frequently bounce radio signals off the atmosphere to get long distance communications, and other times go through the atmosphere to bounce off the moon, or to reach satellites. (hams have put up many small satellites over the years, and there is also a Ham station on the ISS)
The difference between the signals that go through the atmosphere, and the ones that bounce off is wavelength and angle.
You know how if you throw a rock down into a lake, it splashes and sinks, but if you throw it at a low angle it bounces and skips? Radio waves work like that.
And just like a large flat rock skips better, longer wavelengths (low frequency) gets better skip on the atmosphere.
When you see the ham radio guys with LOOONG wire antennas, or wide yagi elements, they are probably using the low frequencies to get ionospheric skip, which can reach around the globe with just a few watts under perfect conditions.
However, if you aim that antenna so that the same signal goes straight up, it blasts right through the ionosphere.
And what do you mean they had no battery on the moon? They had batteries and fuel cells for electricity, which is how they ran the camera and transmitter.
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Of course, if it is a problem caused by the ground equipment, by the test setup, or something unrelated to the flight hardware, this theory goes out the window.
Also, if it is related to damage sustained during reentry or salt water immersion, those are never before tested conditions, so this is the first time they have been able to test it under these conditions, which is important for reusiblity.
So unless this is some new defect discovered unrelated to the fact that it has already been flown, it doesn't reflect badly on their test program, because it is a reusiblity issue, which could not be fully tested until it actually went to space.
It could also be a cycle count issue, and they just reached the limit for some component after extensive testing burns, which would not happen with a production capsule, because they don't burn the engines this much.
It also could be a fatal flaw in a design, but we have no evidence of that, either way, but we have a lot of possibilities that don't spell disaster or prove major errors.
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@RealityIsTheNow , so let's think about this.
Elon had a vision, and so he took his own money and started hiring engineers to figure out how to do it.
But he didn't just pay them, he has been involved all through the process guiding them as they went.
If you watch the Dan Rasky? Videos from nasa (he was a NASA engineer who was sent to work with SpaceX as part of their skill sharing program), he talks about how the different engineering teams would get together for a meeting with Elon and lay out the different options and views, Elon would ask a few questions, and then tell them which way to go.
He is a very involved leader, not just a business man, and all the people who work for him respect his opinions and views, because he has proven himself to them, even if he doesn't have a degree in their field.
So yes, Elon didn't build the engines by himself, but he certainly deserves as much credit for the design and success as anyone else on the crew, because part of doing great things is hiring the right people and working with them to get the job done.
I don't know what direct involvement Von Braun had with the F 1 engine, but even if it was none, it is still just a version of the engine design he developed, so he had every right to be proud of it as a grandpa even if not a father.
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@A.Lifecraft you seem to think that because you "studied physics" that you are smarter than 100 years plus of engineers and scientists and and end users finding every possible way to make one of these terminations fail.
There are only two ways to terminate a wire rope where the termination is stronger than the rope itself, and doesn't derate the cable due to bending it etc.
You 100%of the cable strength with pressure swaged ferrules and fittings, and with Spelter poured ends like this (using either a special epoxy or zinc/white metal/Babbitt metal, etc).
Since hydraulic ferrule presses are a newer invention, and a major investment, Spelter sockets are one of the most common methods to terminate cables, including bridges, crane support cables, rigging slings, barge tow lines, etc, and it's been that way for a very long time.
Tug boats will carry the stuff on board so if one of their giant tow lines gets damaged, they can easily cut off the bad end and put the Spelter socket back on the end.
They have been extensively tested and studied, by people with actual degrees, and the physics of how they work are well understood.
I went to Crosby and did some reading on their research, and I was wrong on one point.
It's almost entirely the wedging action of the tapered zinc or epoxy plug that holds the cable in.
Using epoxy for instance, when it cures you have two forces acting on the wires, adhesion and friction.
They found that either the adhesion or the friction by itself was adequate to seat the plug and create enough wedging action to break the cable.
However, if the plug didn't seat, the adhesion was not enough to hold the wires in, so these fittings are always proof tested after installation to ensure it seats the plug.
So they found that even if the wires were oiled so it would seem that they could slip out easily, there was still enough friction to pull the wedge in and exceed the breaking strength of the cable.
And that's the key point of this termination method, it holds the cable securely enough that the cable will break before it pulls out of the potting material, because of the wedge shape squeezing tighter the more load you add to it.
You also seem to think that zinc is a lubricant, which makes me wonder if you understood how Babbitt bearings worked, and I also suspect that the bearings you referred to are actually Babbitt metal, which is tin based, and not zinc.
Babbitt works by having hard crystals in a soft matrix, providing a low coefficient of friction when used with a polished harder shaft.
And it requires oil to make that happen.
If you run steel directly on babbitt, or zinc, it will tear it up, because it's not a lubricant.
And crimped wire rope wires are not a smooth surface, and so will not easily slide out of metal poured around it.
The fact that it has held for 30 years indicates that it was a proper joint, or it would have failed when originally loaded.
Also, the fact it failed after 30 years points to the likelihood of corrosion outside the potted section, which is a known and likely issue.
So instead of saying that one of the best and most thoroughly tested cable termination methods is a bad idea, maybe we wait for more data on the actual failure.
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@dansorkin6985 if you are traveling to the other side of the world, do you buy a yatch to make the trip yourself, or do you drive your car to the airport, get on a big plane with lots of other people headed the same direction, and then rent a car at the other end to get to the exact house you wanted to go to?
Getting from the earth into orbit is the really hard and expensive part, just like getting across the ocean, so if you can share that cost with others you save a lot of money.
And compared to buying a dedicated orbital rocket, at Starship aspirational prices, you can bolt your satellite to a space tug, get dropped off at the same place as everyone else, and then drive yourself the easy part to your unique destination.
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You left out one key part at the end. Many GPS receivers, for surveying, grading, farming, etc especially, use ALL of the constellations at the same time.
This way, even without RTK (Real-time kinematic positioning, the system used for surveyors, heavy earth moving equipment, and precision farming to get millimeter accuracy, similar to the differential GPS systems you talked about), you can get greatly improved accuracy, because each system has different error modes, different frequencies so you can calculate ionosphere conditions better, plus you get a lot more satellites, so you can get more accurate positioning data.
And combine that with RTK with a base station at a known location, and you can do a GPS controlled CNC milling machine with sub millimeter accuracy! Lol
Or, you know, get accurate survey data with no Total Station and lasers, or have a Grade Control equipped road grader or paving machine make perfect roads, or have an auto steer equipped tractor fertilize a field and keep the drill lined up perfectly between the rows of seeds, while the millennial farmer makes silly YouTube videos and complains about the times the system crashes ;)
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