For Questions That Don't Merit Their Own Thread

[kerbiloid]

The human-scale mechanics is just basically applicable to the elementary particles. Why should the Universe scale differ in this sense?

What are the "baryon number", "up/down/charmed/strange/etc" quarks, "e-/mu-/tau-" neutrinos, etc?

Maybe there are beautiful quasars, up and down galaxies, and so on.

[SunlitZelkova]

How hard is it to keep a scientific discovery secret?

I am writing a story where Imperial Germany survives WWI, and a second European war had erupted by the time fission is discovered in 1938. Would the Germans be able to keep it secret or would it get leaked to other countries?

I'm currently assuming they could keep it secret, but scientists working on the project leak it to other nations purposely in an attempt to preserve the balance of power.

[darthgently]

3 hours ago, SunlitZelkova said:

I'm currently assuming they could keep it secret, but scientists working on the project leak it to other nations purposely in an attempt to preserve the balance of power.

You've presented one of the reasons it wouldn't be kept secret right there.   

But once scientists outside of Germany knew it was possible, they'd be most of the way to figuring it out from what theory they already knew.  And it would be harder to keep the fact that Germany had made a large advance secret than the details of that advance. 

The large advance would be revealed in many difficult to hide details: changes in goods traded comes to mind, especially decreased imports of petroleum products, and increased imports of materials required for reactors if they were to use fission for energy for example

Also, if they were to take advantage of fission in a significant way, it would involve thousands of technicians and workers.  Hard to keep secret 

Edited July 29, 2023 by darthgently

[DDE]

Assuming we stick to combustion-powered engines for the sake of sci-fi hardness, which kind is best-suited for use in power armor?

[kerbiloid]

Is there air around?

[Gargamel]

21 hours ago, DDE said:

Assuming we stick to combustion-powered engines for the sake of sci-fi hardness, which kind is best-suited for use in power armor?

Small diesels.     More torque at low rpm to drive the hydraulic pumps/motors, because you’re not building chain and gear driven armor, it’s going to be actuator powered.   

Deisel will be more efficient than gasoline, and when the fuel tank gets shot, it’s less likely to burn than gas.    
 

Plus, diesel can burn more fuel types than a gas engine.   Vegetable oil runs suitably fine in a Diesel engine, allowing a unit of troops to be more self sufficient if needed.  

[magnemoe]

59 minutes ago, Gargamel said:

Small diesels.     More torque at low rpm to drive the hydraulic pumps/motors, because you’re not building chain and gear driven armor, it’s going to be actuator powered.   

Deisel will be more efficient than gasoline, and when the fuel tank gets shot, it’s less likely to burn than gas.    

Plus, diesel can burn more fuel types than a gas engine.   Vegetable oil runs suitably fine in a Diesel engine, allowing a unit of troops to be more self sufficient if needed.  

Agree, now as you can go a bit crazy, its an design using two chambers and one rod between them, rod goes left, inject, compress and ignite, this push it left who repeat this. Put an hydraulic pump in the center, make it an magnet and have coils around for electricity and to start this. You can have multiple of these for more power and redundancy, things get easier if you don't need an rotating shaft. You could even run the hydraulic pump from batteries if you want to run more silent. Now an pure electrical pump would be more efficient but this could give you some minutes with stealth sprint, once the shooting starts the diesels engines start up. 

Note that this also is true for an 200 kg drone who can hover and similar stuff like large robots. 
So much fun you can do if hybrid, take an turbo on an car, put an electrical engine on it, yes it increase the mass but then you push the gas pedal hard the motor start spinning and you have an compressor until the exhaust pressure get so high it can feed the intake, then you brake hard and the motor take the extra energy for future use. 

[kerbiloid]

Biomethane diesel.

Spoiler

"на пер...чем паре"

"on farting steam", a common idiom

 

[darthgently]

On 7/29/2023 at 6:36 PM, DDE said:

Assuming we stick to combustion-powered engines for the sake of sci-fi hardness, which kind is best-suited for use in power armor?

https://www.liquidpiston.com

[Gargamel]

2 hours ago, darthgently said:

https://www.liquidpiston.com

“Not a Wankel”…… but is clearly a variation of.      

[darthgently]

3 hours ago, Gargamel said:

“Not a Wankel”…… but is clearly a variation of.      

It has some significant differences.  The intake and exhaust arrangement in particular.  It is likely a rotary engine, but isn't that a superset category that merely contains Wankels as one approach?

[magnemoe]

43 minutes ago, darthgently said:

It has some significant differences.  The intake and exhaust arrangement in particular.  It is likely a rotary engine, but isn't that a superset category that merely contains Wankels as one approach?

Will it not have the Wankel issues, yes you can solve the wear issues but will still burn oil? Mazda dropped the Wankel then they got the future emission requirements.

[darthgently]

8 minutes ago, magnemoe said:

Will it not have the Wankel issues, yes you can solve the wear issues but will still burn oil? Mazda dropped the Wankel then they got the future emission requirements.

Could be. The zeitgeist is not great for yet another ICE right now either.  On the other hand Liquid Piston has some DARPA and USAF contracts for drone engines and forward operation power generators.  And something tells me there will be a significant consumer market for compact emergency EV chargers and range extenders. 

As for wear, materials science is always advancing.  This may also be why they are focused on smaller engines where current materials at that scale are perhaps more up to the challenges wrt deformation and related.

In that vein, there are many old ideas out there left behind because materials were not up to the task that should be revisited as materials science advances.  We will likely build practical ornithopters, for example, once materials are up to the task.  Space elevators too!

 

[SunlitZelkova]

What’s up with N.A. Kozyrev’s theories of time?

It seems they are rejected in the west but study continues at various Russian institutions.

[DDE]

On 7/31/2023 at 12:13 AM, magnemoe said:

Agree, now as you can go a bit crazy, its an design using two chambers and one rod between them, rod goes left, inject, compress and ignite, this push it left who repeat this.

Usually this leads to two rods, and two crankshafts, both on the Chieftain and the T-64.

[kerbiloid]

12 hours ago, SunlitZelkova said:

What’s up with N.A. Kozyrev’s theories of time?

It seems they are rejected in the west but study continues at various Russian institutions.

https://ru-m-wikipedia-org.translate.goog/wiki/Причинная_механика?_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=ru&_x_tr_pto=wapp

Officially considered conspiracy/marginal, but well-known to the enthusiasts.

[JoeSchmuckatelli]

18 hours ago, darthgently said:

something tells me there will be a significant consumer market for compact emergency EV chargers and range extenders

I was thinking about military application of EV.  There are certain advantages... But the ability to drive 300 miles, refuel in 10 minutes and drive another 300 isn't one. 

We do have experience with 'swapping packs' - removing and replacing entire engines in the field... And so it's possible to do similar with batteries. 

Only problem is that the vehicle needs to be designed for that, and you need to add a whole new logistics support line to your system (battery pack trucks alongside fuel trucks, stores, central charging, etc) 

If you could build a compact system that could provide a full recharge in 20 minutes on 5 gallons of fuel?  You'd make a killing. 

[TheSaint]

1 hour ago, JoeSchmuckatelli said:

I was thinking about military application of EV.  There are certain advantages... But the ability to drive 300 miles, refuel in 10 minutes and drive another 300 isn't one. 

We do have experience with 'swapping packs' - removing and replacing entire engines in the field... And so it's possible to do similar with batteries. 

Only problem is that the vehicle needs to be designed for that, and you need to add a whole new logistics support line to your system (battery pack trucks alongside fuel trucks, stores, central charging, etc) 

If you could build a compact system that could provide a full recharge in 20 minutes on 5 gallons of fuel?  You'd make a killing. 

If only there were some way that we could put the fuel directly into the vehicle....

[darthgently]

1 hour ago, JoeSchmuckatelli said:

If you could build a compact system that could provide a full recharge in 20 minutes on 5 gallons of fuel?  You'd make a killing. 

If an ICE can go x miles on 5 gallons, you aren't going to get more than x miles recharging an EV from 5 gallons, but I get what you mean.  It would probably be more like turning the EV into a hybrid with the range extender running while the vehicle is in motion.  One would still have the benefits of regenerative braking etc, but could also have the advantage of not freezing to death as easily in a blizzard after your heater, defroster, wipers, lights, getting stuck/unstuck twice, and traction control overhead turned your 300 mile range to 100 miles in the middle of Montana in winter

The main advantage to range extenders is the ICE can run at a constant and optimum RPM for charging and the fuel can be stored for a fairly long time and only tapped when urgent during exceptional situations.  Most commutes wouldn't touch it

As for military use, EVs are very quiet especially compared to most military multi fuel diesels.  The extenders would allow the vehicles to recharge or extend range in motion of course, but when more discretion and stealth might be needed, with batteries charged and extenders shut down, they could tip toe more stealthily at 0 dark-thirty blacked out using night vision through areas more easily

Edited August 1, 2023 by darthgently

[kerbiloid]

The Sun composition is: 92.1% of H, 7.9% of He, 0.1% of other junk.

So, if vent out all that hydrohelium, the solid rest of its mass will be ~2*10²⁷ kg ~= 330 earthes.

If in a first approximation take the junk composition equal to the Earth matter, it will be a Superearth about 6 times larger than the Earth in size.

***

But as the solar matter is ionized, there can be now chemical compounds or crystallic structures.

So, the intrasolar junkball shhould be gaseous (plasmatic, doesn't matter).

Thus, the elements should be distributed proportionally to their atomic mass.

Even if not remove the hydrohelium.

Doesn't it mean, that there should be a huge uranium ball at center of the Sun?

***

The estimated amount of uranium in the Earth crust is 40..100 trln t (from different sources).

Let's take 100 trln, as the core and the mantle have some, too.

So, the solar uranium ball should be ~100 trln t.
At normal density, it's ~5 000 km³. I.e. ~20 km in diameter.

***

As we know, there is https://en.wikipedia.org/wiki/Oklo_Mine

~2 bln years ago, when threes and the concentration of 235 were higher, there was a natural reactor.

The solar junkball should be full of carbon and hydrogen (i.e. moderators), and surrounded by thick layer of hydrogen, i.e. the natural moderator-reflector.

The junkball mass is a natural tamper, inertially withstanding the uranium fission pressure.

***

As 4 bln years ago the 235 concentration was ~20%,, which is HEU, with critical mass less than 1 t, shouldn't be the beginning of the Sun existence a one big fission badaboom?

[magnemoe]

On 8/1/2023 at 3:45 PM, JoeSchmuckatelli said:

I was thinking about military application of EV.  There are certain advantages... But the ability to drive 300 miles, refuel in 10 minutes and drive another 300 isn't one. 

We do have experience with 'swapping packs' - removing and replacing entire engines in the field... And so it's possible to do similar with batteries. 

Only problem is that the vehicle needs to be designed for that, and you need to add a whole new logistics support line to your system (battery pack trucks alongside fuel trucks, stores, central charging, etc) 

If you could build a compact system that could provide a full recharge in 20 minutes on 5 gallons of fuel?  You'd make a killing. 

And they are silent, who is an advantage. But I suspect the military to be most interested in hybrids for many reasons.  They give the best of both an EV and an diesel powered car and you can use the car as an generator and its battery to power an base. Also lots of stuff works as weapon platforms and sensors or communication hub. 
For tanks and artillery the batteries would just be there for sensors and crew support so active but stationary. 

[Rocket Witch]

On 6/22/2023 at 7:51 AM, monophonic said:

I hear and the captions read them talking about the landing sequence. It would actually make sense as the spacecraft would pass approximately over the Eye (guesstimated) one orbit before the planned splashdown area in the Atlantic. So seeing the Eye would somewhat accurately match to a specific stage in the landing sequence and predict splashdown in less than two hours.

Ah, that makes more sense, thanks. I found the video by sorting by 'most viewed' so wasn't expecting much and I made the erroneous presumption that the video creator probably meant the docking, as landing would be much less of a "sequence" and not need to have its progress "tracked" by the spacecraft crew themselves.

Edited August 9, 2023 by Rocket Witch

[RevanX_LSR]

On 8/2/2023 at 12:10 PM, kerbiloid said:

The Sun composition is: 92.1% of H, 7.9% of He, 0.1% of other junk.

So, if vent out all that hydrohelium, the solid rest of its mass will be ~2*10²⁷ kg ~= 330 earthes.

If in a first approximation take the junk composition equal to the Earth matter, it will be a Superearth about 6 times larger than the Earth in size.

***

But as the solar matter is ionized, there can be now chemical compounds or crystallic structures.

So, the intrasolar junkball shhould be gaseous (plasmatic, doesn't matter).

Thus, the elements should be distributed proportionally to their atomic mass.

Even if not remove the hydrohelium.

Doesn't it mean, that there should be a huge uranium ball at center of the Sun?

***

The estimated amount of uranium in the Earth crust is 40..100 trln t (from different sources).

Let's take 100 trln, as the core and the mantle have some, too.

So, the solar uranium ball should be ~100 trln t.
At normal density, it's ~5 000 km³. I.e. ~20 km in diameter.

***

As we know, there is https://en.wikipedia.org/wiki/Oklo_Mine

~2 bln years ago, when threes and the concentration of 235 were higher, there was a natural reactor.

The solar junkball should be full of carbon and hydrogen (i.e. moderators), and surrounded by thick layer of hydrogen, i.e. the natural moderator-reflector.

The junkball mass is a natural tamper, inertially withstanding the uranium fission pressure.

***

As 4 bln years ago the 235 concentration was ~20%,, which is HEU, with critical mass less than 1 t, shouldn't be the beginning of the Sun existence a one big fission badaboom?

The uranium was all dispersed out through the sun. and the core was so hot that uranium would be gaseous anyway, so it could not accumulate in substantial quantity.

[kerbiloid]

1 hour ago, JNSQFan said:

The uranium was all dispersed out through the sun. and the core was so hot that uranium would be gaseous anyway, so it could not accumulate in substantial quantity.

The gaseous uranium would anyway be exponentially-radially distributed, just statistically.

And as it's 238/2 times heavier than H2, it would concentrate at the CoM.

[tomf]

The uranium won't suddenly come into a sphere at the centre, it will slowly diffuse inwards. The heat from fission reactions will expand the core slowing the reaction so the uranium will be burned up at a steady rate, just like the hydrogen fusion is stable.

Also the subs fusion output is 10^26 watts, the fusion of all that uranium is about the same number of joules so the fission of all the uranium in the sun is about a seconds worth of fusion.