For Questions That Don't Merit Their Own Thread

[TheSaint]

10 hours ago, kerbiloid said:

Microprose F-117 had the Mainstay hunting on regular basis.

That was one of my favorite Amiga games. That and Red Storm Rising.

Edited January 12, 2022 by TheSaint
Conflated Name

[DDE]

5 hours ago, SunlitZelkova said:

It was rare, but may not be anymore. China has developed the PL-15, a very long range air-to-air missile (200-300km range) which is probably intended to shoot down USAF support assets, like tankers and AWACS.

Before the PL-15/AWACS-tanker vulnerability hype began though, the Soviet Union developed the R-37 air-to-air missile, with a max range of 300km. It was delayed by the collapse of the USSR and ensuing economic problems of Russia, but now is entering service.

And on the surface-to-air front, we have the elusive beast that is the 40N6 missile, which puts "400 km" into the S-400. However, it requires a non-standard TEL, of which there has been few sightings, and none of the actual launch containers. The same goes for S-400's other non-standard missile, the quad-packed 9M96.

Edited January 12, 2022 by DDE

[magnemoe]

10 hours ago, TheSaint said:

That was one of my favorite Amiga games. That and Red Storm Rising.

Played the F-117 on PC and remember going after the Soviet radar planes. 
Unique for early 3d games the in game model ended up being more realistic than the box art  

Pretty low polygon count here  
Just read the Red storm book, did not know it was an game, but it was important in the book but there it had an two man crew and an gun. 
The game plane also had an gun, the F-117 was an one man craft and did not have an gun. 

The F22 has an gun and F-22 pilots has sneaked up on F-15 and F-16 and done gun kills in excises. No it would not be an stealth killing as both the pilot and the plane will call this out very loudly.

[JoeSchmuckatelli]

39 minutes ago, magnemoe said:

the plane will call this out very loudly

The only flying gun that matters says, "Brrrrt!"

[magnemoe]

7 hours ago, JoeSchmuckatelli said:

The only flying gun that matters says, "Brrrrt!"

Lasers don' brrr   
Assume they are the next big thing for air combat. First two uses is probably return of the defensive armament  on large planes, who can take an multiple ton system, down the line know the F-35 has an upgrade path replacing the gun with an laser. 
On the other hand  you can make machine cannon shells smart  

 

[SOXBLOX]

18 minutes ago, magnemoe said:

Lasers don' brrr   
Assume they are the next big thing for air combat. First two uses is probably return of the defensive armament  on large planes, who can take an multiple ton system, down the line know the F-35 has an upgrade path replacing the gun with an laser. 
On the other hand  you can make machine cannon shells smart  

 

The first step right now is a podded mostly-defensive laser for the F-16. I think the same system can go on C-130s later. Not sure if there's anything in the works for the F-35, but a laser plus the F-35's situational awareness and networking would be brutal.

And who knows about the upcoming NGAD (6th gen fighter) program(s). Maybe they incorporate laser weapons from the outset... I'm sure you could stick something on the B-21, too.

[monophonic]

5 hours ago, SOXBLOX said:

The first step right now is a podded mostly-defensive laser for the F-16. I think the same system can go on C-130s later. Not sure if there's anything in the works for the F-35, but a laser plus the F-35's situational awareness and networking would be brutal.

That's the second step overall. Laser-based self protection systems are already operational, but most physical harm they can inflict is if they manage to burn out the IR sensors of the incoming missiles. Mostly they are designed to dazzle and/or confuse the seeker. High energy systems capable of physically damaging the missile's airframe, like the SHiELD you mention, are indeed coming up but not operational quite yet. I count them as the second generation of self defence lasers. They will be quite useful against small drones not really worth a missile shot too.

[Wizard Kerbal]

Some redditor was being annoying when I said Solar System all uHm oUr sTaR sySTeM iS tHe SolAr sySteM otHErS arE caLleD plAneTarY oR stAr sYsteMs so I just sighed and came here. 
 

Is this true?

if i do i feel like it’s nit-picky like uhm theres a Swedish b17 be specific and call it the flying
fortress of just fortress

[JoeSchmuckatelli]

31 minutes ago, Wizard Kerbal said:

Some redditor was being annoying when I said Solar System all uHm oUr sTaR sySTeM iS tHe SolAr sySteM otHErS arE caLleD plAneTarY oR stAr sYsteMs so I just sighed and came here. 
 

Is this true?

if i do i feel like it’s nit-picky like uhm theres a Swedish b17 be specific and call it the flying
fortress of just fortress

Technically (at least in English/Western tradition) our star is Sol... and this is the Solar system.  Some people get really nitpicky - but in common usage you can talk about an exoplanet's solar system as having only 7 planets.  Betelgeusian system gets a bit wordy, and many others are worse.

Stellar system kinda sounds like it did well on its coloring assignment, anyway - regardless of how 'technically correct' the phrase may be.

[kerbiloid]

And even if the star doesn't have a personal name, there are star catalogs always ready to help you.

For example, Alpha Centauri is also known as:

Quote

• α Alpha Centauri А: HD 128620, HR 5459, CP−60°5483, GCTP 3309.00A, LHS 50.
• α Alpha Centauri B: HD 128621, HR 5460, GCTP 3309.00B, LHS 51.

So, their common planetary system (if it exists) can be called:
Alphacentaurian System
HD128620&21ian System
HR5459&60ian System
CPminus605483ian System
GCTP330900ian System
LHS50&51ian System

(of course, in addition to Tolimanian System, Rigilcentaurian System, and other historical names).

Edited January 14, 2022 by kerbiloid

[ARS]

Is it possible to have a nuclear thermal rocket with the engine design that have adjustable thrust level and effiiency in the atmosphere? high-thrust low-efficiency at low altitude before gradually switching to  low-thrust high efficiency at high altitude, by adjusting the nozzle diameter and the level of fission heat? For high thrust-low efficiency, the nozzle diameter becomes smaller while the fission heat level increases (yielding high gas pressure in the chamber).  For low thrust-high efficiency, the nozzle diameter becomes larger while the fission heat level decreases (yielding low gas pressure in the chamber)

[K^2]

2 hours ago, ARS said:

Is it possible to have a nuclear thermal rocket with the engine design that have adjustable thrust level and effiiency in the atmosphere? high-thrust low-efficiency at low altitude before gradually switching to  low-thrust high efficiency at high altitude, by adjusting the nozzle diameter and the level of fission heat? For high thrust-low efficiency, the nozzle diameter becomes smaller while the fission heat level increases (yielding high gas pressure in the chamber).  For low thrust-high efficiency, the nozzle diameter becomes larger while the fission heat level decreases (yielding low gas pressure in the chamber)

An NTR will already run as close to the melting point as possible for both efficiency and thrust, so I don't think adjusting reactor temperature buys you anything. Reactor fuel efficiency really isn't a factor, after all, and so long as you can dump the heat, thermal losses are kind of irrelevant. The efficiency you're after is always the propellant efficiency, so you might as well always run as hot as possible.

Likewise, chamber pressure is as high as you can make it given temperatures involved and materials available. Going to lower pressure never helps you with thrust or efficiency. Therefore, you really have just two things you control, the fuel flow and nozzle diameter. And really, it's one thing, because at a given pressure and temperature, for given nozzle diameter, a certain amount of propellant exits through said nozzle and has to be replenished by the pumps pushing propeller out of the tanks, through the heat exchanger, and out the nozzle.

For any high thrust application, the limiting factor on NTR will always be heat exchange. You can try to open up the nozzle, force more propellant through exchanger to maintain pressure, and get a little bit more thrust with colder exhaust, but you quickly hit diminishing returns. If the channels in your exchanger are too wide, heat only gets transferred to propellant that flows close to surfaces, and you get nothing. If you make channels small, you increase drag. If you try to force more propellant through narrow channels faster, drag goes up. There's really only so much propellant you can push through at high speed without increasing size of heat exchanger, which is extra weight, which is what we're trying to counter with thrust in the first place.

So you really have to change tactics. You have to heat slow-moving propellant and then mix it with cold propellant in the chamber to reach some sort of intermediate temperature. You effectively have a two stage rocket, where first stage is an NTR, and second works kind of like an afterburner. Which is viable, but now we're talking about dumping tons of propellant. So a question might be, if you're pushing through atmosphere, why not let air in from outside via ram scoop? And if you do that, instead of heating your propellant, which is presumably hydrogen, why not just ignite it with air mixture instead? For a conventional chemical rocket, it's usually not worth the complexity of mixing in airbreathing since you're carrying oxidizer anyways, though, of course, there are prototypes even for that. But with NTR, if you're not bothering with an oxidizer tank and you're looking to help yourself out with early ascent, a ramejet seems like a far better choice.

 

[kerbiloid]

3 hours ago, ARS said:

Is it possible to have a nuclear thermal rocket with the engine design that have adjustable thrust level and effiiency in the atmosphere? high-thrust low-efficiency at low altitude before gradually switching to  low-thrust high efficiency at high altitude, by adjusting the nozzle diameter and the level of fission heat? For high thrust-low efficiency, the nozzle diameter becomes smaller while the fission heat level increases (yielding high gas pressure in the chamber).  For low thrust-high efficiency, the nozzle diameter becomes larger while the fission heat level decreases (yielding low gas pressure in the chamber)

First of all, in a nuke, unlike the chemical, fuel =/= propellant.
The fuel is what you burn to get energy (uranium, deuterium, etc), the propellant is what you accelerate to throw back (any substance to be heated or ionized and electromagnetically thrown).

Power = Force * velocity

The reactor gives you P ~ const.

v (the exhaust speed) depends on either the temperature of the propellant or its electromagnetic acceleration.

F = P/v.
The faster is the exhaust, the lower is the available force, being limited by the reactor power.

The temperature of the propellant is limited by the reactor and the engine construction, so the thermal exhaust speed of the propellant is limited by several thousand kelvins, and thus several km/s.

The ionization and electromagnetic acceleration is not limited by the temperature so much, and a hundred thousands of km/s is possible.

So, you should heat some additional propellant with great atomic mass (say, air or water) by the reactor heat exchanger or/and by the ionized jet to provide high thrust/low ISP on launch.
Actually the engine will work on launch as an open cooling system of the reactor.

Then use low-thrust/high-ISP ions acceleration in zero-G.

The ultimate case of the electromagnetic acceleration is the thermonuclear reactor throwing back ionized alpha-particles, either used as propellant themselves, or heating some propellant to get intermediate ISP.
And as any way a rocket-powerful reactor would provide a lot of neutrons which it's impossible to catch (the protection wall would be enormously high, it's usual about 6 m of concrete thick), thus unlikely any one type of reactor but the aneutronic fusion reactor will ever be used in a crewed spacecraft. As this will happen probably by the end of XXI, so the chemicals will stay the only human-rated engines for a century more.

Edited January 14, 2022 by kerbiloid

[ARS]

@K^2, @kerbiloid I see, thanks for the answer

[JoeSchmuckatelli]

Under water volcano explodes near Tonga 

https://www.cnn.com/2022/01/15/asia/tsunami-warning-tonga-volcano-intl-hnk/index.html

Satellite video 

[StrandedonEarth]

43 minutes ago, JoeSchmuckatelli said:

Under water volcano explodes near Tonga 

https://www.cnn.com/2022/01/15/asia/tsunami-warning-tonga-volcano-intl-hnk/index.html

Satellite video 

Yeah, explodes big-big. Shockwaves detected in Fiji and NZ.

 

[kerbiloid]

https://naukatehnika-com.translate.goog/vodorodno-bornyij-reaktor.html?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=ru

[DDE]

22 minutes ago, kerbiloid said:

https://naukatehnika-com.translate.goog/vodorodno-bornyij-reaktor.html?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=ru

They can't possibly hope to patent laser-driven H-B fusion, can they?

[kerbiloid]

1 hour ago, DDE said:

They can't possibly hope to patent laser-driven H-B fusion, can they?

They probably can patent the exact device and something specific to it, as the H-B fusion is commonly known.

[JoeSchmuckatelli]

Something I did not know: the inner solar system is still chock full of dust. 

https://www.nasa.gov/feature/goddard/2021/nasa-s-parker-solar-probe-sees-venus-orbital-dust-ring-in-first-complete-view

[JoeSchmuckatelli]

Okay, who here knew there was a 'strange area' above the North Pole?

NASA Rocket to Study Mysterious Area Above the North Pole | NASA

Quote

“At around 250 miles above Earth, spacecraft feel more drag, sort of like they’ve hit a speed bump,” ...That’s because the air in the cusp is noticeably denser than air elsewhere in the spacecrafts’ orbits around Earth. 

 

Edited January 16, 2022 by JoeSchmuckatelli

[magnemoe]

On 1/15/2022 at 5:01 PM, StrandedonEarth said:

Yeah, explodes big-big. Shockwaves detected in Fiji and NZ.

 

That was an big one, not as energetic 

[DDE]

11 hours ago, JoeSchmuckatelli said:

Okay, who here knew there was a 'strange area' above the North Pole?

NASA Rocket to Study Mysterious Area Above the North Pole | NASA

 

The Internet, soon afterwards

[JoeSchmuckatelli]

Speaking of Volcanoes: Floating Stones in the South Pacific:

Volcano F is the origin of 'floating stones' (phys.org)

Quote

some volcanic eruptions produce a very porous type of rock with a density so low that it does float: Pumice. An unusually large amount of it is currently drifting in the Southwest Pacific towards Australia. When it was first sighted in the waters around the island state of Tonga at the beginning of August, it almost formed a coherent layer on the ocean's surface

 

[kerbiloid]

Floating stones... Volcanoes... 

Wait...

That's what they were for!

Spoiler

The original ones have brought their ancestor by water, but there is no proper floating stone there, so the population became stranded on island.

They keep making them, but have to leave staying.

So adorable...