totm nov 2023 SpaceX Discussion Thread

[tater]

 

[sevenperforce]

  On 5/26/2020 at 1:36 PM, sevenperforce said:

I want to see an IVA suit which acts as the pressurized liner for a not-pressure-bearing exoskeleton EVA suit.

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Comparison, for anyone interested:

  Reveal hidden contents

This is the AX-5 hard shell suit:



All the joints are circular because that's the only way to hold a seal between two solid surfaces. There are like 5 different circular joints just to permit full ROM for the single elbow joint.

Compare to this:

Or this:

This way you only have a single free joint at each elbow/knee. 

 

[CatastrophicFailure]

Hope the swelling goes down. Really should see a doctor, looks like a nasty glandular condition there... 

[tater]

 

[Spaceception]

Gwynne Time says a few more years or so.

https://aviationweek.com/defense-space/space/spacex-aims-starship-crew-flights-2023

I can't read the rest of the article though

 

I can't wait to see Superheavy development start. That's gotta be soon.

[magnemoe]

  On 5/26/2020 at 3:21 PM, sevenperforce said:

Comparison, for anyone interested:

  Reveal hidden contents

This is the AX-5 hard shell suit:



All the joints are circular because that's the only way to hold a seal between two solid surfaces. There are like 5 different circular joints just to permit full ROM for the single elbow joint.

Compare to this:

Or this:

This way you only have a single free joint at each elbow/knee. 

 

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Plate armor joints are not locked in place like the hardsuit. Its purpose is not to contain pressure but to protect the wearer from hits. This it why you have the prostitution on the knees and elbows.  At the shoulders and hips the plates slides over each others, you can see this on the mittens. 
And that suit is probably the best plate armor ever created, it was created for an English king. Note that this suit is insane and specialized, you would not want to ride an horse in it for once it was designed for fighting on foot. 
As I understand it was an jousting event there they would use blunt swords but it was probably referee who would judge hits, it was never used as the fight was canceled. 
 Most plate armor had more areas without plate typically back of knee and the crouch. Even this suit don't have armor in the armpit, it has chainmail there however, You wore padded jackets and trousers under it and it had chainmail on places who was not covered in plate so it was not an soft target.it was an reason stuff like warhammers and Halberd became common. 

[tater]

 

[MinimumSky5]

I was 16 when the last shuttle launched, and not yet that interested in space, so seeing a crew manifest of 4 people is quite surreal for me.

[sevenperforce]

  On 5/26/2020 at 6:05 PM, MinimumSky5 said:

I was 16 when the last shuttle launched, and not yet that interested in space, so seeing a crew manifest of 4 people is quite surreal for me.

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I was a few days away from turning 12, and ditto.

  On 5/26/2020 at 4:54 PM, magnemoe said:

As I understand it was an jousting event there they would use blunt swords but it was probably referee who would judge hits, it was never used as the fight was canceled. 

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Off-topic, but this romanticized version of tournaments is not entirely true. Early tournaments had no judges, only list marshals to stop things if they got too violent; the goal was to use less-lethal combat methods to capture opponents, take their armor, and hold them for ransom. It was basically the same as a regular battle, except without the part at the end where all the losers get stabbed to death. We have contemporary writings from the 1200s talking about how tournaments really should start using blunted weapons, suggesting strongly that it was not generally the case up to that point.

  On 5/26/2020 at 4:54 PM, magnemoe said:

Plate armor joints are not locked in place like the hardsuit.

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The hardsuit joints are not locked in place, either.

  On 5/26/2020 at 4:54 PM, magnemoe said:

Its purpose is not to contain pressure but to protect the wearer from hits. This it why you have the prostitution on the knees and elbows.  At the shoulders and hips the plates slides over each others, you can see this on the mittens.

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The purpose of an EVA suit is more than just containing pressure; it's also supposed to protect the wearer from MMOD strikes, provide thermal management, and much more. The current ISS EMU uses eight different fabric layers just for MMOD protection.

A combination hard-and-soft-shell suit would be designed such that the suit liner (which is basically just a tweaked IVA suit) contains the pressure, while the outer hard shell contains the volume. If the outer shell can prevent the inner liner from expanding except into joint spaces, then you can move without having to fight the internal pressure.

Think about how a bicycle innertube will expand to many times its ordinary volume if pumped up outside of the tyre, but if it is placed inside the tyre, it is mechanically contained, and the tyre itself does not have to be pressure-bearing.

[RCgothic]

Oops.

[RealKerbal3x]

  On 5/26/2020 at 8:01 PM, RCgothic said:

Oops.

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Huh. I wonder if they'll be able to just pop it back into shape. It is just a stainless steel tube after all

[mikegarrison]

  On 5/26/2020 at 7:20 PM, sevenperforce said:

Think about how a bicycle innertube will expand to many times its ordinary volume if pumped up outside of the tyre, but if it is placed inside the tyre, it is mechanically contained, and the tyre itself does not have to be pressure-bearing.

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The tire *does* have to bear the pressure. This is exactly what it is doing by "constraining the volume". The role of the inner tube is to be impermeable and prevent leakages, not to support any "pressure".

[tater]

 

[Mad Rocket Scientist]

Countdown clock

[Scotius]

I have a chance of seeing the launch live for once   If road crews fixing the street finish on time, and there will be no congestion as i'll be returning from work

[sevenperforce]

Interesting...

https://electrek.co/2020/05/24/tesla-roadster-spacex-package-elon-musk-james-bond/

Elon says that the "SpaceX package" Roadster will come with cold-gas thrusters (from a COPV, periodically refilled by an onboard battery-powered compressor) for cornering control, downforce, and boost. Supposedly the license plate will pop down to reveal the boost thruster.

All very silly but fun. This could actually be useful (as opposed to just obnoxious) on an up-rated Cybertruck. If you're towing really heavy stuff, having extra downforce and extra starting force are both very useful in short bursts. Also good for pushing out of the mud.

  On 5/26/2020 at 8:25 PM, mikegarrison said:

  On 5/26/2020 at 7:20 PM, sevenperforce said:

Think about how a bicycle innertube will expand to many times its ordinary volume if pumped up outside of the tyre, but if it is placed inside the tyre, it is mechanically contained, and the tyre itself does not have to be pressure-bearing.

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The tire *does* have to bear the pressure. This is exactly what it is doing by "constraining the volume". The role of the inner tube is to be impermeable and prevent leakages, not to support any "pressure".

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My mistake -- I said "pressure-bearing" when I should have said "airtight". The tyre does not have to be airtight. You can force a screwdriver in along the side of an inflated tire without releasing the air (though I do not recommend it, as the chance of accidentally puncturing the innertube is significant).

A segmented hard shell like the HALO Spartan suit or the Iron Man suit or good old fashioned plate armor can be pressure-bearing without being airtight if it has the right liner. That liner can then do double duty as an IVA suit, which is really just there to prevent sudden death if the cabin depressurizes.

[tater]

18 hours...

 

[Guest]

  On 5/26/2020 at 9:13 PM, sevenperforce said:

Elon says that the "SpaceX package" Roadster will come with cold-gas thrusters (from a COPV, periodically refilled by an onboard battery-powered compressor) for cornering control, downforce, and boost. Supposedly the license plate will pop down to reveal the boost thruster.

All very silly but fun. This could actually be useful (as opposed to just obnoxious) on an up-rated Cybertruck. If you're towing really heavy stuff, having extra downforce and extra starting force are both very useful in short bursts. Also good for pushing out of the mud.

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Actually, someone already tried something similar (a downforce fan) on an F-1 car. It worked pretty well, but it was banned the next season (the usual fate of such innovations if they don't massively boost safety). CGTs would work in that role, too, though a fan would be more efficient. This is pointless for normal road use, and I don't think it'd fly with any racing authority, so in the end, it's another useless gimmick. 

[mikegarrison]

  On 5/26/2020 at 10:00 PM, Dragon01 said:

Actually, someone already tried something similar (a downforce fan) on an F-1 car. It worked pretty well, but it was banned the next season (the usual fate of such innovations if they don't massively boost safety). CGTs would work in that role, too, though a fan would be more efficient. This is pointless for normal road use, and I don't think it'd fly with any racing authority, so in the end, it's another useless gimmick. 

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The original "downforce fan car" was the Chaparral 2J. It was not made for Formula 1, but for the Can-Am series. https://en.wikipedia.org/wiki/Chaparral_Cars

It was primarily because of Chaparral's innovations that most motorsports series eventually banned moveable aerodynamic surfaces. Cynically, this was because nobody else had engineers good enough to understand what Jim Hall was doing, and they didn't want to have to try to compete with him when he ironed out the bugs in his cars.

Later on, there was the https://en.wikipedia.org/wiki/Brabham_BT46#Brabham_BT46B that did run one race in Formula 1.

Edited May 26, 2020 by mikegarrison

[Guest]

I wasn't talking about Chaparral, it's also a good example, though not the only one:
https://en.wikipedia.org/wiki/Brabham_BT46

It wasn't actually used much because of politics, but it worked, and quite well, at that. In fact, much like the Chaparral, too well for its own good. Funnily enough, "movable aerodynamic surfaces" are still a thing in F-1, DRS uses them, so whatever rule they came up with to ban fan cars had to be more narrow (that, or they specifically excluded DRS from it). Either way, I'd expect CGTs to last about as long in motorsports as the fans did, if they're not already covered.

Edited May 26, 2020 by Guest

[tater]

 

[StrandedonEarth]

 

[CatastrophicFailure]

 

[mikegarrison]

  On 5/27/2020 at 1:19 AM, StrandedonEarth said:

 

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Brings up some bad memories. There was this one time I had to go witness an engine noise test. I was on site for three or four weeks, doing *nothing*. This was early '90s -- the first web browser hadn't even been invented yet. We did have one day of good weather -- but it was on a weekend, and the engine supplier did not have weekend overtime budget authorization. It was *so* frustrating.

When the test was finally done, it took less than 24 hours from start to finish.

[sevenperforce]

  On 5/27/2020 at 1:38 AM, CatastrophicFailure said:

 

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Does NOT look how I expected.

The high chamber pressure means the extended skirt is shorter. 

I like big bells and I cannot lie