Interstellar shield or aerobraking shield?

[t_v]

Since we are on the topic of parts, I just realized that there are absolutely massive RCS blocks poking out of the rear fuel tanks. 

[Bej Kerman]

On 11/2/2022 at 6:25 AM, intelliCom said:

Out of curiosity, what would an atmosphere like Duna's do to interstellar speeds? Or an atmosphere even 1% of Duna's?

Educated guess, disintegrate the shield at the front that's only meant to deal with the one atom per cubic centimeter of interstellar space, then disintegrate the rest of the now unshielded ship.

[MechBFP]

4 hours ago, Bej Kerman said:

Educated guess, disintegrate the shield at the front that's only meant to deal with the one atom per cubic centimeter of interstellar space, then disintegrate the rest of the now unshielded ship.

I don’t think it would even have time to disintegrate. I think the ship would just crumble into itself like a car hitting a wall. 
Or rather more like that video of a jetplane hitting a wall where the whole thing just disintegrates from getting smashed into a pancake from the force itself, rather than from atmospheric heating. 
 

Edited November 3, 2022 by MechBFP

[magnemoe]

On 11/4/2022 at 12:06 AM, MechBFP said:

I don’t think it would even have time to disintegrate. I think the ship would just crumble into itself like a car hitting a wall. 
Or rather more like that video of a jetplane hitting a wall where the whole thing just disintegrates from getting smashed into a pancake from the force itself, rather than from atmospheric heating. 
 

I did some tests in KSP 1: "Feasibility study of Laythe aerobrake for large ship or base coming in from high velocity transfer, 50-100 ton test with 5 large heatshields 1 front and 4 brakes behind", result: heat shields was destroyed once aerodynamic braking become an force and ship blew up, an problem with Laythe and Eve is that you are falling into an deep gravity wheel who increases your velocity.

[mcwaffles2003]

It couldn't effectively work as a debris shield since its comparatively small in regards to the ships diameter. Interstellar debris wont form a bow shock since its to dispersed at that scale to act in a fluid manner. My guess is high altitude aerobraking,either for the ship itself, or the crew container that may detach in front of it... Unless it just guards the crew...

[Pthigrivi]

18 hours ago, magnemoe said:

I did some tests in KSP 1: "Feasibility study of Laythe aerobrake for large ship or base coming in from high velocity transfer, 50-100 ton test with 5 large heatshields 1 front and 4 brakes behind", result: heat shields was destroyed once aerodynamic braking become an force and ship blew up, an problem with Laythe and Eve is that you are falling into an deep gravity wheel who increases your velocity.

Ive managed to aerobrake coming into Laythe and Eve. I think I just had to come in higher in their atmosphere to get into an elliptical orbit of Jool and Eve that lets you come around for a second and 3rd pass. You really need a mod that gives trajectory factoring drag for this, and its the reason I think having drag and overheat prediction would be so important for new and old players alike. 

[magnemoe]

32 minutes ago, Pthigrivi said:

Ive managed to aerobrake coming into Laythe and Eve. I think I just had to come in higher in their atmosphere to get into an elliptical orbit of Jool and Eve that lets you come around for a second and 3rd pass. You really need a mod that gives trajectory factoring drag for this, and its the reason I think having drag and overheat prediction would be so important for new and old players alike. 

Yes, has done circulation with aerobrake at Eve many times, capture is also very dependent on your weight, something lightweight like an capsule and a inflatable heat shield can come in at kerbin at 6 km/s, slows down an land while something weighing 50 ton is much harder. 

[Bej Kerman]

On 11/2/2022 at 1:25 AM, Minmus Taster said:

its clearly a massive heatshield:

Reasons against it being a heatshield:

It is possibly too small depending on the re-entry physics

Aero forces aren't slowing down a skyscraper at safe altitudes, and if the skyscraper ends up very low in the atmosphere, said skyscraper will flex and will snap somewhere around the thin Girder-noodle section

The dV saved from an aerobrake maneuver will be negligible compared to the dV provided by the ship itself. By the time it's travelling slow enough to not disintegrate at altitudes drag becomes useful, it would take barely a fraction of a percent of the starting dV to burn into an orbit.

Reasons for it being a heatshield: well clearly if it's brown and patchy then it could only be a heatshield, right?

Sorry for the necro, but this line of discussion is too interesting to pass up.

[GoldForest]

2 hours ago, Bej Kerman said:

Reasons against it being a heatshield:

It is possibly too small depending on the re-entry physics

Aero forces aren't slowing down a skyscraper at safe altitudes, and if the skyscraper ends up very low in the atmosphere, said skyscraper will flex and will snap somewhere around the thin Girder-noodle section

The dV saved from an aerobrake maneuver will be negligible compared to the dV provided by the ship itself. By the time it's travelling slow enough to not disintegrate at altitudes drag becomes useful, it would take barely a fraction of a percent of the starting dV to burn into an orbit.

Reasons for it being a heatshield: well clearly if it's brown and patchy then it could only be a heatshield, right?

Sorry for the necro, but this line of discussion is too interesting to pass up.

Aerobraking isn't impossible, you'll just have to be very careful. 

It also depends on the planet. Aerobraking on Kerbin probably wouldn't do anything, but aerobraking at Jool would probably show results. 

Of course, it could be a heat shield against interstellar medium. From what I understand, interstellar medium can have hot gases in them, so having a heat shield might work for that? Of course, physical material will chip away at the heat shield too, so your heat shield becomes a regular shield at that point, chipping away at the material kind of like entry heat would. 

Not really a necro as necro kind of implies off topic, at least from my understanding, that's how the mods see it. Since this information is still relevant, it's not off topic and ergo not necro. 

Hmmm, another thought is that it's a heat shield, and they're testing the heat generation system while also testing interstellar craft, so the heat shield could literally be just a test part that they brought along for the ride. Which we all know people are going to do. Don't tell me you're not going to dive bomb Kerbin or whatever planet at interplanetary (Or even interstellar) speeds, because we all know everyone will do it at one point... for "science"

Edited January 10, 2023 by GoldForest

[Bej Kerman]

1 hour ago, GoldForest said:

Of course, it could be a heat shield against interstellar medium

The ambience around Kerbol would be a million times more concerning than the interstellar medium if heat was an issue. Nope, the trouble with the interstellar medium is how dangerous rogue particles are when you're ploughing through them at fractions of the speed if light. It's a shield, I am confident that it's definitely to keep the interstellar medium from eroding at the ships payload, but it's most definitely not a heat shield, and for my given reasons it is most certainly not something to be used for aerobreaking. If structural integrity isn't the problem, it's the fact that aerobreaking would have little benefit given that the leftover dV would be more than sufficient for a capture burn. If we're being conservative for our first missions, the leftover dV could be enough for a grand tour.

1 hour ago, GoldForest said:

Don't tell me you're not going to dive bomb Kerbin or whatever planet at interplanetary speeds, because we all know everyone will do it at one point... for "science"

You know us all too well

[GoldForest]

11 minutes ago, Bej Kerman said:

The ambience around Kerbol would be a million times more concerning than the interstellar medium if heat was an issue. Nope, the trouble with the interstellar medium is how dangerous rogue particles are when you're ploughing through them at fractions of the speed if light. It's a shield, I am confident that it's definitely to keep the interstellar medium from eroding at the ships payload, but it's most definitely not a heat shield, and for my given reasons it is most certainly not something to be used for aerobreaking. If structural integrity isn't the problem, it's the fact that aerobreaking would have little benefit given that the leftover dV would be more than sufficient for a capture burn. If we're being conservative for our first missions, the leftover dV could be enough for a grand tour.

You know us all too well

What about aerobraking to use gravity sling shot? Would that be beneficial to interstellar craft?

[Bej Kerman]

1 minute ago, GoldForest said:

What about aerobraking to use gravity sling shot? Would that be beneficial to interstellar craft?

Elaborate?

[GoldForest]

7 minutes ago, Bej Kerman said:

Elaborate?

You want to get to To Be Announced. Going their directly will cost you lots of Delta V. Deb Deb has a gas giant with a moon. Using said gas giant and moon could save you Delta V, but you have to do a minor aerobrake to line up with the moon. 

[Bej Kerman]

1 hour ago, GoldForest said:

You want to get to To Be Announced. Going their directly will cost you lots of Delta V. Deb Deb has a gas giant with a moon. Using said gas giant and moon could save you Delta V, but you have to do a minor aerobrake to line up with the moon. 

As I discussed previously, such a maneuver is borderline pointless when you've already done 99.99% of your deceleration burn to end up slow enough to do the aerobrake. Might as well do the remaining 0.01% using your engine instead of an extremely risky maneuver

[GoldForest]

2 minutes ago, Bej Kerman said:

As I discussed previously, such a maneuver is borderline pointless when you've already done 99.99% of your deceleration burn to end up slow enough to do the aerobrake. Might as well do the remaining 0.01% using your engine instead of an extremely risky maneuver

But where's the Kerbal spirit in using the engine and not trying a death defying maneuver?

[magnemoe]

1 hour ago, GoldForest said:

But where's the Kerbal spirit in using the engine and not trying a death defying maneuver?

Firebird 1 at hardbrake.

Yes it was Duna in 100 days, so came in hot, main issue was to keep drag at center line so ship did not flip. 

[Jacob Kerman]

2 hours ago, GoldForest said:

But where's the Kerbal spirit in using the engine and not trying a death defying maneuver?

Gonna have to back this one up.

[Minmus Taster]

9 hours ago, Bej Kerman said:

Reasons against it being a heatshield:

It is possibly too small depending on the re-entry physics

Aero forces aren't slowing down a skyscraper at safe altitudes, and if the skyscraper ends up very low in the atmosphere, said skyscraper will flex and will snap somewhere around the thin Girder-noodle section

The dV saved from an aerobrake maneuver will be negligible compared to the dV provided by the ship itself. By the time it's travelling slow enough to not disintegrate at altitudes drag becomes useful, it would take barely a fraction of a percent of the starting dV to burn into an orbit.

Reasons for it being a heatshield: well clearly if it's brown and patchy then it could only be a heatshield, right?

Sorry for the necro, but this line of discussion is too interesting to pass up.

That wasn't my argument though, I was talking about how it could be a debris shield of some kind. And I only called it a "heatshield" for simplicities sake (though at that speed the particles your traveling through might actually cause dangerous heating).

[Bej Kerman]

8 hours ago, Minmus Taster said:

That wasn't my argument though, I was talking about how it could be a debris shield of some kind. And I only called it a "heatshield" for simplicities sake

The mistake there was thinking that "heat shield" could be used as a synonym for "debris shield" despite them being two very different things - the ISS is covered in Whipple shielding, but it's not surviving re-entry, even if the crew is very careful about how they re-enter 

8 hours ago, Minmus Taster said:

(though at that speed the particles your traveling through might actually cause dangerous heating)

The ship isn't ploughing through hot compressed air, the problem it's dealing with is the kinetic energy of these particles. With a re-entry, a capsule is slow enough that individual molecules don't act like tiny micrometeoroids, but all that air is being compressed against the heat shield, making it very hot.

For interstellar travel, rather than dealing with temperature, the purpose of these shields is to make sure the payload and the bits holding the ship together aren't eroded over time by the medium, because at these speeds, individual molecules do act like tiny micrometeoroids.

[Drakenred65]

I think I remember reading that one of the problems with Ram scoops of interstellar gas was that, oddly, there’s too much drag for them to actually work.

 

that and beyond a certain point, your velocity gets high enough that dust and jeneral friction start becoming a problem, with heat from impacts may create a bow shock type phenomenon. It’s posible that now shock from vaporizing particles may help deflect some particles as well?

[Bej Kerman]

8 minutes ago, Drakenred65 said:

I think I remember reading that one of the problems with Ram scoops of interstellar gas was that, oddly, there’s too much drag for them to actually work.

 

In order to use it as fuel, you have to capture it first, and at some point the exhaust velocity isn't fast enough to make up for the velocity of incoming particles.

[SciMan]

Those ram-scoops (especially the ones based on magnetic fields and low-density plasma) do make a very good braking system when attempting to stop at the destination end of an interstellar journey. All stars have a stellar wind comprised of mostly ionized protons and high velocity electrons, and the intensity of the stellar wind increases with increasing stellar mass and increasing stellar temperature.

So all you need to bring for most of the braking phase of the interstellar journey (unless you're traveling to a brown dwarf) is something that can generate a large magnetic field in front of the craft, which is... probably something you were already carrying to protect you from interstellar debris (along with some method of ionizing the incoming interstellar media).

But yes, for the coast phase of an interstellar journey (if there is one), you'll need some form of debris shielding. For the sake of simplifying the GAME, KSP 2 could very easily have ONE part that does both "heat-shield" and "interstellar debris shield" and "radiation shadow shield" all at once, with the variant you select designating the type of shielding it provides (or maybe multiple types, most common combination that would be needed is radiation shadow shield and heat shield at the same time).

Because the more functions you can cram into one physics-enabled part, the better the game is gonna run. And I'm sure we all want to get 60FPS or more at 4K resolution with the game looking fantastic and the ship we're guiding consisting of thousands of parts, right? We can get all that, except that last one barring some revolution in how KSP/Unity calculates physics. Which means cramming multiple functions into one part is a good idea. And even if we COULD get all those things I mentioned, it's still a good idea, because that means we have more parts left over to do OTHER things on the vessel.
Last I checked, landers usually take up at least 10 parts, science landers take like 50 parts or more, and if you want a "do anything at this kind of planet" lander, that's gonna be almost 100 parts.
An interstellar mothership is gonna need to be made up of a lot of parts (probably over 1000), and that's even if the mothership is the kind that can spit out an Orbital VAB and still have enough resources left over to construct a bunch of landers to build at least a starter colony.

[Bej Kerman]

5 minutes ago, SciMan said:

Because the more functions you can cram into one physics-enabled part, the better the game is gonna run.

We're beyond that - let's remember it's a completely different game, one where the ratio between the base FPS and the FPS when flying a 300 part vehicle shouldn't be too big.

This depends on how realistic the idea of a 3-in-1 shield is. Protecting your vehicle from being blasted with plasma and keeping it protected from erosion due to kinetic bombardment from tiny flecks of spacedust are two very different challenges.

[SciMan]

Right, you seem to have misunderstood my concept. I meant you DO get separate shield parts that perform separate functions.

What I meant was that in the VAB parts list, there would only be one "Shielding" part, which would have a lot of customization options on it (procedural options of many kinds), one of those options would be to change it between "Heat Shield", "Debris Shield", and "Radiation Shield".
When you select one of those options, the part would (probably drastically) change its appearance to suit its selected function.
So it would look like an ablative (or not) heat shield for the Heat Shielding option.
It would look like a Whipple Shield for the Debris Shielding option.
And it would look like a relatively thick plate of Tungsten for the Radiation Shielding option.

Obviously, because the Radiation shielding option is made of Tungsten, it would ALSO make a VERY good heat shield, provided that you ALSO need the radiation shielding in any case (otherwise it's a poor choice because it's so much heavier than a "normal" heat shield).
Tungsten is still Tungsten, and Tungsten is widely known as the metal with the highest known melting point (Carbon beats it out, but Carbon is not a metal, so Carbon might be chosen for a non-ablative "just a heat shield" heat shield).

When would you need both radiation and heat shielding?
Well eventually the game is supposed to be giving us a bunch of high tech sci-fi engines, and one thing I know about high-tech sci-fi engines is that they tend to spew a lot of radiation, so you're gonna need the radiation shield. But hopefully those high tech sci-fi engines include a few that can be used from sea level of Kerbin (or even Eve), and that means you need the radiation shield, you can probably easily get enough delta-V out of the engines to make an SSTO, and that means you need the heat shield so you can land the SSTO again.

And if you're asking yourself "Why land the SSTO?", I have an answer.
I don't think it's a good idea to be mass-producing these high tech engines that must cost absolutely absurd amounts of money (so much money that KSP 2 isn't even featuring a money mechanic because EVERYTHING is too expensive and making money to support launching them distracts from the core experience), so why would you want to only use them once?
It seems incredibly wasteful to just dispose of them after a single mission, and even if money is no object the engines still have a cost in the materials used to construct them so it's still wasteful to only use them once. And you SHOULD be able to move LARGE amounts of cargo to orbit with these high tech sci-fi engines that spew radiation (depending on the size of the radiation shield you need of course).

Additionally, with the routine mission automation feature that's eventually going to be put in the game (I forget where specifically on the roadmap that is at the moment, but it doesn't matter for purposes of this discussion), the rate you can fly these SSTO rockets to resupply your very first Orbital VAB that's probably in Kerbin orbit is determined directly by how quickly they can be turned around, re-fueled, get a new payload, moved to the launch pad, and launched again. Meaning you might not need all that many of them to support an impressive rate of resource transfer.

[magnemoe]

On 1/10/2023 at 10:06 PM, Minmus Taster said:

That wasn't my argument though, I was talking about how it could be a debris shield of some kind. And I only called it a "heatshield" for simplicities sake (though at that speed the particles your traveling through might actually cause dangerous heating).

Yes it was added as it looks cool for an pretty realistic starship. 


Yes model has some issues. most obvious one is that its 1600 meter long and you push it to .7 c. Yes its stretching it, but you also has an lack of energy. Now launching this uses so much energy you need to be an K1+ civilization anyway so something don't add up. 
And rotating that shield 90 degree the the anti matter engines plume will not hit it. 

On the upside it has an fusion engine for adjusting orbit and similar because you want to flex.  Battleship Yamato has 8" secondary guns for the same reason, that was mostly changed to 5" as it worked better against aircraft while still being rapid fire and heavy hitting secondaries.