For Questions That Don't Merit Their Own Thread

[DDE]

1 hour ago, kerbiloid said:

The Earth is under attack!

And they say Michael Bay is a bad director.

[kerbiloid]

31 minutes ago, Jestersage said:

Are there any solar panel systems that is re-foldable?

https://en.wikipedia.org/wiki/Integrated_Truss_Structure#P6,_S6_trusses

20 minutes ago, DDE said:

And they say Michael Bay is a bad director.

He just perfectly feels his target group.

And knows, where to spend the money, where to save.

[Admiral Fluffy]

Why is Lunar/Martian dirt called Regolith?

[Jacke]

49 minutes ago, Admiral Fluffy said:

Why is Lunar/Martian dirt called Regolith?

https://en.wikipedia.org/wiki/Regolith#Etymology

Quote

Regolith (/ˈrɛɡəlɪθ/)^[1] is a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock. It includes dust, broken rocks, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestrial planets and moons.

Etymology

The term regolith combines two Greek words: rhegos (ῥῆγος), 'blanket', and lithos (λίθος), 'rock'.^[2][3][4] The American geologist George P. Merrill first defined the term in 1897, writing:

In places this covering is made up of material originating through rock-weathering or plant growth in situ. In other instances it is of fragmental and more or less decomposed matter drifted by wind, water or ice from other sources. This entire mantle of unconsolidated material, whatever its nature or origin, it is proposed to call the regolith.^[5]

 

[Jestersage]

10 hours ago, kerbiloid said:

https://en.wikipedia.org/wiki/Integrated_Truss_Structure#P6,_S6_trusses

So nothing else? Basically the only refoldable solar panels are those on Space Stations? (earlier example: the Zarya module and Saylut)

Edited July 26, 2021 by Jestersage

[kerbiloid]

34 minutes ago, Jestersage said:

So nothing else?

Iirc, they were needing to retract/extend some panels on Mir on something's docking to let it safely pass, but found a way to not do it, while it anyway was possible.

Edited July 26, 2021 by kerbiloid

[Silavite]

I was reading about materials when this statement caught my eye:

Quote

It is known, for instance, that body-centered cubic materials such as low alloy steels undergo a transition from ductile to brittle behavior at low temperatures; therefore, such metals are generally not suitable for structural applications at cryogenic temperatures. The face-centered cubic metals such as the austenitic stainless steels normally do not show a transition from ductile to brittle behavior at low temperature.

Source (page 283/284 of the PDF, section 12.5.7)

How does the crystal structure influence the emergence of a ductile to brittle transition?

[StrandedonEarth]

4 hours ago, Silavite said:

How does the crystal structure influence the emergence of a ductile to brittle transition?

Sorry, but the best answer I can come up with is.... 

42

[DDE]

2020 Olympics have official national kimono designs

[JoeSchmuckatelli]

7 hours ago, Silavite said:

ow does the crystal structure influence the emergence of a ductile to brittle transition

When you get a metallurgist or PE to explain this - it's really interesting.  Had a case dealing with a failure and both sides wanted to argue fault.  Enter the Experts. We got down into the woods with a scanning electron microscope and had some fun. 

It's been so long that I'm actually looking forward to the answer to remind me of what I've forgotten in the intervening years. 

7 hours ago, Silavite said:

ow does the crystal structure influence the emergence of a ductile to brittle transition

. 

The key is the type of steel /alloy the austenitic, the ferritic, and the martensitic

https://www.google.com/search?q=austenitic&oq=austrntic&aqs=chrome.1.69i57j0i13i433l2j0i13l2.6433j1j4&client=ms-android-samsung-ss&sourceid=chrome-mobile&ie=UTF-8 

https://www.google.com/search?q=ferritic&client=ms-android-samsung-ss&ei=AggAYczZJY-4tAbE66iwCQ&oq=ferritic&gs_lcp=ChNtb2JpbGUtZ3dzLXdpei1zZXJwEAMyBAgAEEMyBAgAEEMyBQgAELEDMgIIADICCAAyAggAMgQIABBDMgIIADoECAAQRzoCCCk6BQgpEKABOggIABDqAhCPAVCAzAVYpOwFYLX1BWgBcAF4AIAB9AGIAfQBkgEDMi0xmAEAoAEBoAECsAEeyAEIwAEB&sclient=mobile-gws-wiz-serp

https://www.google.com/search?q=martensitic&client=ms-android-samsung-ss&ei=AggAYczZJY-4tAbE66iwCQ&oq=martensitic&gs_lcp=ChNtb2JpbGUtZ3dzLXdpei1zZXJwEAMyBAgAEEMyBAgAEEMyBAgAEEMyAggAMgIIADICCAAyAggAMgIIADoECAAQRzoCCCk6BQgpEKABOggIABDqAhCPAVDhOliPTmCYW2gBcAF4AIABhQGIAYUBkgEDMC4xmAEAoAEBoAECsAEeyAEIwAEB&sclient=mobile-gws-wiz-serp

 

Edited July 27, 2021 by JoeSchmuckatelli

[kerbiloid]

2 hours ago, DDE said:

Can this aerobrake?

Spoiler

 

 

[TheSaint]

12 hours ago, Silavite said:

I was reading about materials when this statement caught my eye:

Source (page 283/284 of the PDF, section 12.5.7)

How does the crystal structure influence the emergence of a ductile to brittle transition?

I used to know all this from nuclear power school. Unfortunately, almost 30 years in IT has not preserved that knowledge. I do remember that neutron radiation increases the number of interstitial defects in the crystal structure of metals, which increases their brittleness, raising their nil-ductility temperature. Funny the things that you remember.

[kerbiloid]

On 7/26/2021 at 7:38 PM, Jestersage said:

Basically the only refoldable solar panels are those on Space Stations? (earlier example: the Zarya module and Saylut)

https://en.wikipedia.org/wiki/Kristall

Quote

One of Kristall's solar panels was removed and re-deployed on Kvant-1 in 1995. That solar panel was later disposed of in November, 1997.

 

[Jestersage]

16 hours ago, kerbiloid said:

https://en.wikipedia.org/wiki/Kristall

 

But not crew transport. Okay. That's all I need to know -- need to decide on some solar panels/placement for my crew transport.

[kerbiloid]

They found a tetraquark.

http://lhcb-public.web.cern.ch

It's twice charmed (2 charmed, 0 uncharmed), positive (+1), and has a mass of 3,875 GeV, and lives very long (10..500 times longer that other things of its mass).

A very nice tetraquark. Be like him.

***

But better they would found a metastable metallic hydrogen.
Because what should we do with a tetraquark? It even doesn't burn.

[SOXBLOX]

3 hours ago, kerbiloid said:

tetraquark

This is such a cool word.

[ARS]

Just like F-4 Phantom's moniker of 'the triumph of thrust over aerodynamic', which basically 'with enough thrust, everything can fly', if you have infinite Delta-v, does it mean you can say 'screw orbital mechanics' and do old-school dogfight in space?

Edited July 29, 2021 by ARS

[Spacescifi]

1 hour ago, ARS said:

Just like F-4 Phantom's moniker of 'the triumph of thrust over aerodynamic', which basically 'with enough thrust, everything can fly', if you have infinite Delta-v, does it mean you can say 'screw orbital mechanics' and do old-school dogfight in space?

Should come as no surprise that I researched this before.... but the answer is... yes.... IF your RCS also have infinite RCS with the required thrust too.

 

Do note that IRL your RCS would look like flaming main enines to pull this off LOL.

 

Honestly with IRL physics propellant is a precious resource and the more massive the ship the longer it takes to even to even have a reasonably good turn rate that won't take several seconds.

 

To be sure, if ships fly around at a constant 1g that still gives some time to dodge.

 

But if ships can jump drive or warp anywhere like in popular scifi, then you won't be dodging much when ships jump within weapons range and missiles are seconds away from impact.

Long story short is that unless you purposely handicap warp or jump ability in some way, all spaceships are sitting ducks to any ship that warps in and blasts them. Meaning combat would attempt to be done at warp or via jumping, since that would be the most effective way of NOT being shot.

Edited July 29, 2021 by Spacescifi

[SOXBLOX]

If you don't mind either A) performing Immelman turns with the radius of a small planet or B) being reduced to chunky salsa by the g-forces required to tighten your turn radius.

[JoeSchmuckatelli]

10 hours ago, SOXBLOX said:

If you don't mind... being reduced to chunky salsa by the g-forces required to tighten your turn radius.

What do you think the stasis field is for? 

[magnemoe]

On 7/30/2021 at 12:40 AM, ARS said:

Just like F-4 Phantom's moniker of 'the triumph of thrust over aerodynamic', which basically 'with enough thrust, everything can fly', if you have infinite Delta-v, does it mean you can say 'screw orbital mechanics' and do old-school dogfight in space?

it would not be an dogfight as in airplanes I think as you could not turn like an plane, guess it would be more dodging in random directions who is plausible with very good engines. 
It will also change because fighter planes has only forward facing guns, you can rotate an spaceship freely, an spaceship able to do random dodge for some time will be so large its no reason to not use turrets and you have no drag who makes turrets on planes an problem. Lasers make turrets even easier and direct energy weapons can not be dodged at close range. 

[TheSaint]

1 hour ago, magnemoe said:

it would not be an dogfight as in airplanes I think as you could not turn like an plane, guess it would be more dodging in random directions who is plausible with very good engines. 
It will also change because fighter planes has only forward facing guns, you can rotate an spaceship freely, an spaceship able to do random dodge for some time will be so large its no reason to not use turrets and you have no drag who makes turrets on planes an problem. Lasers make turrets even easier and direct energy weapons can not be dodged at close range. 

People keep trying to put space warfare in a box. "It's going to be like aerial warfare," or, "It's going to be like naval warfare." It's going to be like space warfare. And I think that any forces that try to fight it with paradigms from aerial or naval warfare are going to lose.

[Spacescifi]

24 minutes ago, TheSaint said:

People keep trying to put space warfare in a box. "It's going to be like aerial warfare," or, "It's going to be like naval warfare." It's going to be like space warfare. And I think that any forces that try to fight it with paradigms from aerial or naval warfare are going to lose.

 

Essentially correct.

 

When relying on rocketry with limited propellant and you donot have torchships that can do 1g for days, the most valuable ship, for battle, trade, exploration, or anything else, is the giant tanker full of propellant.

If that goes kaboom, the local fleet is either stranded or cannot go certain places or intercept certain stuff anyway.

 

Tankers are the unsung hero spaceships seldom ever seen in pop scifi.

 

Never. Ever. Fly solo. Two vessels minimum can tether and spin for 1g or less.

 

Four vessels and you can have several tankers at your beck and call.

 

Of course I prefer orion drive tankers, since they can save their propellant for the fleet that needs it since they rely on a limited suppply of bombs for propulsion.

[kerbiloid]

13 hours ago, JoeSchmuckatelli said:

What do you think the stasis field is for? 

According to R. Sheckley's  A Ticket to Tranai, it's to keep the wife there when she's not needed, keeping the harmony in the family.

On 7/30/2021 at 1:40 AM, ARS said:

if you have infinite Delta-v, does it mean you can say 'screw orbital mechanics' and do old-school dogfight in space?

It does mean that an anti-you missile has the unlimited delta-V, too, and it isn't afraid of high-G.

[Jacke]

3 hours ago, TheSaint said:

People keep trying to put space warfare in a box. "It's going to be like aerial warfare," or, "It's going to be like naval warfare." It's going to be like space warfare. And I think that any forces that try to fight it with paradigms from aerial or naval warfare are going to lose.

Except that some principles will still transfer.  A strong one today in many situations is who shoots effectively first wins.