For Questions That Don't Merit Their Own Thread

[magnemoe]

On 5/4/2022 at 3:27 AM, Gargamel said:

Commercial drone is commercial.   Extremely high failure rates due to them not being designed for combat environments is completely acceptable.  

Military hardware usually has a long vetting process.   That includes a rate of failure determined by some statistical analysis.  To make a combat safe drone that meets that failure rate and is light enough to be easily man portable and have a useful range, let alone fly, is apparently not an easy task.   
 

Bringing ad hoc equipment into a battle is one thing, being issued bad equipment is another. 

Excellent point, you also have the factor that commercial drones did evolve fast so the first military specification ones probably became outdated before they was close to ready. 

Military also has added requirements like harder to jam and how to behave then jammed also I also assume an base station relay in case the enemy use artillery on the position or other tricks. 
This is much more an problem in Ukraine than in the war on terror. 
Its obviously an growing area 

 

[steve9728]

On 5/8/2022 at 4:46 PM, magnemoe said:

Excellent point, you also have the factor that commercial drones did evolve fast so the first military specification ones probably became outdated before they was close to ready. 

Military also has added requirements like harder to jam and how to behave then jammed also I also assume an base station relay in case the enemy use artillery on the position or other tricks. 
This is much more an problem in Ukraine than in the war on terror. 
Its obviously an growing area 

 

That's one of the reasons why I hate current pandemic: many relevant and practical 'gadgets' were on display at the 2021 Zhuhai Airshow and will probably continue to be at future. But you know...

If the batteries doesn't work so well, then don't use it

For  example:

In addition to this, there is already a considerable market for large Chinese fixed wing drones in Middle Eastern countries. Some Middle Eastern customers have responded to the Chinese manufacturer to see if they could consider adding air combat capabilities to these UAVs.

Edited May 10, 2022 by steve9728

[magnemoe]

3 hours ago, steve9728 said:

That's one of the reasons why I hate current pandemic: many relevant and practical 'gadgets' were on display at the 2021 Zhuhai Airshow and will probably continue to be at future. But you know...

If the batteries doesn't work so well, then don't use it

Impressive but feel an hybrid design is better and at some size its better to go fixed wing unless you need WTOL or hover, you don't want to hover with something this size for an combat mission. 

[steve9728]

1 hour ago, magnemoe said:

an hybrid design

Agree but I considering my dad's hybrid car, in the UAV level I don't think it's need to hybrid in same one drone: you can provide a fossil fuel version and a batteries version. Because anything that go to sky all needs to consider the it's own weight. The answer they gave in same airshow was: use a bigger fixed wing UAV with stealth design, carrying the loitering munitions in the bomb bay:

 

1 hour ago, magnemoe said:

unless you need WTOL or hover

Somebody: nihao

But actually I pretty like this ‘chaotic evil’ one:

[ARS]

Is it possible to reenter the atmosphere stealthily for undetected planetary insertion (to the extent of visual and radar invisibility) with proper controlled deceleration in orbit (and during reentry) to minimize atmospheric friction and heating (that creates a highly visible plasma) with the combination of radar and visual countermeasure (optic camo, anti-radar coating, etc.)

[Terwin]

18 minutes ago, ARS said:

Is it possible to reenter the atmosphere stealthily for undetected planetary insertion (to the extent of visual and radar invisibility) with proper controlled deceleration in orbit (and during reentry) to minimize atmospheric friction and heating (that creates a highly visible plasma) with the combination of radar and visual countermeasure (optic camo, anti-radar coating, etc.)

I don't see why not.

You would need something to hide your plume from the surface while braking from orbital velocity towards a speed where you would not have significant friction heating.(Presumably you would do this over the day-side of the planet so scattered sunlight would reduce your visibility)

Then do a controlled reentry where you keep your speed down and your radar-reflective surface intact until you are low enough for aerodynamic flight, at which point you can be just as stealthy as a B2 as you come down to land on a platform extended above the surface of the ocean by your secret underwater base.

[JoeSchmuckatelli]

56 minutes ago, ARS said:

Is it possible to reenter the atmosphere stealthily for undetected planetary insertion (to the extent of visual and radar invisibility) with proper controlled deceleration in orbit (and during reentry) to minimize atmospheric friction and heating (that creates a highly visible plasma) with the combination of radar and visual countermeasure (optic camo, anti-radar coating, etc.)

I worked on a story idea like this several years ago... 

The economy had a strong space based component with lots of commercial traffic reentry - and the stealth pilot would shadow a drone ship to 'share the plume' then peel off once in atmospheric flight. 

As for limiting the likelihood of being spotted via this method - I'm confident that it is 'a way' (especially if over the Pacific) ... But I don't know whether it's technically possible or even a good idea given turbulence 

[darthgently]

1 hour ago, ARS said:

Is it possible to reenter the atmosphere stealthily for undetected planetary insertion (to the extent of visual and radar invisibility) with proper controlled deceleration in orbit (and during reentry) to minimize atmospheric friction and heating (that creates a highly visible plasma) with the combination of radar and visual countermeasure (optic camo, anti-radar coating, etc.)

If clouds are part of the scenario then timing for entry at a location and time where very thick cloud cover, perhaps even a major storm, could mask re-entry detection from the ground.  I'm having trouble imagining how one could mask re-entry from well placed space based assets unless using a trojan horse like approach @JoeSchmuckatelli suggests

[kerbiloid]

The aerobraking is a conversion of the reentry vehicle kinetic energy into the heat energy of the air.

The path length is limited by the air drag and cannot be infinitely long.

So, whatever you use for braking, you can probably hide the reentry vehicle itself, but not the tail of ionized hot air, because it anyway receives receives the same amount of energy from the hypersonically fast body.

***

Unless you use a fusion reactor to brake softly by engines, but then its radiator panels would glow like a lamp.

***

Also, remember that the ionized tail emits in various wave length ranges, and would be visible on the sky background in one of them.

[Gargamel]

There's also the thought that one could re-enter and look like a meteor just streaking across the sky, with a good solid single massive retroburn to possibly resemble an explosion, and then a soft powered landing when you are in a location not covered by radar etc.    Having the craft ditch flammable solids to give the appearance of it breaking up.  

[JoeSchmuckatelli]

40 minutes ago, Gargamel said:

There's also the thought that one could re-enter and look like a meteor just streaking across the sky, with a good solid single massive retroburn to possibly resemble an explosion, and then a soft powered landing when you are in a location not covered by radar etc.    Having the craft ditch flammable solids to give the appearance of it breaking up.  

Grin - I also had that worked into the story. 

Classic 'sub warfare' deception stuff! 

[StrandedonEarth]

2 hours ago, ARS said:

Is it possible to reenter the atmosphere stealthily for undetected planetary insertion (to the extent of visual and radar invisibility) with proper controlled deceleration in orbit (and during reentry) to minimize atmospheric friction and heating (that creates a highly visible plasma) with the combination of radar and visual countermeasure (optic camo, anti-radar coating, etc.)

If you have the dV, it shouldn’t be too difficult. Antigravity (“gravity planet”) would make it simple

[kerbiloid]

1 hour ago, Gargamel said:

There's also the thought that one could re-enter and look like a meteor just streaking across the sky, with a good solid single massive retroburn to possibly resemble an explosion, and then a soft powered landing when you are in a location not covered by radar etc.    Having the craft ditch flammable solids to give the appearance of it breaking up.  

And shoot decoys to look like an innocent meteor shower.

[steve9728]

“Sir I find something really fast and really hot on screen. And it’s just as big as baseball. Any thoughts?”

[JoeSchmuckatelli]

10 hours ago, steve9728 said:

“Sir I find something really fast and really hot on screen. And it’s just as big as baseball. Any thoughts?”

That kind of stuff does happen - and often gets other assets called in to see if they can determine what it was. 

However due to lag time there are often gaps in the coverage and now we get congressional testimony about little green men 

[mikegarrison]

Meteors enter all the time.

[Hyperspace Industries]

So, I was messing about while eating biltong (a South African snack), and I put the two ends of my multimeter on a bit of biltong and it read: around 200 millivolts!

My question is, HOW!?

I was trying to make thermocouples, so I had originally measured the resistance, around 5 mega ohm. I also in later tests determined that:

Wrapping it in aluminum foil can boost the voltage to 400-500 millivolts.

Temperature does not appear to effect it, at least not a temperature gradient, so this is not the thermoelectric effect.

For those curious, biltong is essentially just meat, dried, salted, and it contains saltpeter.

[kerbiloid]

Spoiler

 

 

Now with meat.

[Gargamel]

5 hours ago, kerbiloid said:

  Reveal hidden contents

 

 

Now with meat.

Possibly.  
 

You’re probably just seeing the discharge of any static buildup that has occurred across the leads and possibly on the meat itself. 

[Hyperspace Industries]

9 hours ago, kerbiloid said:

  Hide contents

 

 

Now with meat.

Doesn’t that require different electrode materials? I used the exact same type of electrodes on both sides, and they don’t corrode.

3 hours ago, Gargamel said:

Possibly.  
 

You’re probably just seeing the discharge of any static buildup that has occurred across the leads and possibly on the meat itself. 

Wouldn’t that only provide power for a short time, because I tried it a day later, and it still worked.

Could it be something to do with microbes digesting the meat?

[monophonic]

1 hour ago, Hyperspace Industries said:

Doesn’t that require different electrode materials? I used the exact same type of electrodes on both sides, and they don’t corrode.

Your meat contains both sodium (from salt, or sodium chloride) and potassium (from saltpeter, or potassium nitrate). Their electrode potentials are about -2.71V for sodium and -2.92V for potassium. The difference is approximately 200mV, which is what you measured. Aluminum goes up to -1.66V so theoretically you could see well over a volt with the wrapper. Not knowing how the meat was prepared, how you had it on the wrapper and which points exactly you measured makes it impossible to say what is in reality happening. Stuff like whether the salt and saltpeter were mixed together or if one side of the meat was treated with salt and the other with saltpeter can make a difference.

[CFYL]

I heard that Mars Insight is about to lose power. About to say goodbye to another lander.

Is there a way of building *something that can work like a electric fan to blow the dust off on future probes?

Or are RTGs good enough for extended missions? I think I heard *somewhere that, voyager 2 is still in contact with our planet till this day. And engineers got the engines to burn for a few minutes.

[StrandedonEarth]

11 minutes ago, CFYL said:

I heard that Mars Insight is about to lose power. About to say goodbye to another lander.

Is there a way of building *something that can work like a electric fan to blow the dust off on future probes?

Or are RTGs good enough for extended missions? I think I heard *somewhere that, voyager 2 is still in contact with our planet till this day. And engineers got the engines to burn for a few minutes.

A fan, probably not. The air is too thin. A wiper would likely scratch the panels. Probably the best bet would be a small compressor and tank. But whatever the option, it adds mass, which has to be balanced against the odds of a critical something else failing before the panels silt up…

[Gargamel]

2 minutes ago, StrandedonEarth said:

A fan, probably not. The air is too thin

That was my first reaction too, but we do have a working flying drone on the planet, so maybe it’s not too far fetched an idea. 
 

But yes, as you mentioned, is the added mass worth the trouble?   This is a stationary lander.  It has probably done all then useful science it can, and is now basically a weather station.  How actually useful is an extended mission for a lander like this?  

[StrandedonEarth]

Just now, Gargamel said:

That was my first reaction too, but we do have a working flying drone on the planet, so maybe it’s not too far fetched an idea. 

Good point. All that is needed is a place for the scout chopper to land on the panels, maybe with some sort of hold-down clamps or stirrups so the chopper can generate more wind without lifting off. Then the scout copter can do double duty, scouting and cleaning panels….

But what cleans the panels on the scout?