[1.2.2] Active Ablation v1.0.2 - Electric Powered Lifting Surface Ablation

[Starman4308]

If it helps, I looked into reentry heat loads a bit.

The Wikipedia page on ablative heatshields gives a range of figures, and I went with a conservative 150 W/cm^2 thermal load. Even for a 1.25m heatshield, you're talking about wicking away 920 kW of heat generation (920 kJ/sec), and a rough estimate would put efficiency at 60% tops (given a perfect Carnot engine, shockwave temperature 2000K, part temperature 800K). Realistically, you're looking at > 2000 kW of cooling necessary for a 1.25m heatshield.

For perspective:

Wall outlets in the US are capped at around 1.6 kW

The official spec on the S9G reactor powering the Virginia-class submarines is 30,000 kW of peak power

Lithium-ion batteries store about 850 kJ/kg

Water's heat of vaporization is 2,257 kJ/kg

Given how most people peg 1 kW to be around 1 EC/sec, I have two main conclusions:

KSP batteries are hilariously underpowered by a factor of around 40.

Even assuming a generous 40 kW = 1 EC/sec, if you're aiming for realism, you'd want active cooling to draw 50 EC/sec to cool a 1.25m circle at peak load. That's... kinda brutal.

[captinjoehenry]

Actually I am pretty sure that peak load is lower than the current setting.  As it stands at peak load in atmosphere for large spaceplanes it is 10s of thousands of EC/s.  Honestly it needs to be heavily reduced for it to really work.  Or at least adjusted a fair bit for the pure EC system to work for the other ones you are just running pumps to move a cooling fluid

Edited December 16, 2016 by captinjoehenry

[Esquire42]

6 minutes ago, Starman4308 said:

If it helps, I looked into reentry heat loads a bit.

The Wikipedia page on ablative heatshields gives a range of figures, and I went with a conservative 150 W/cm^2 thermal load. Even for a 1.25m heatshield, you're talking about wicking away 920 kW of heat generation (920 kJ/sec), and a rough estimate would put efficiency at 60% tops (given a perfect Carnot engine, shockwave temperature 2000K, part temperature 800K). Realistically, you're looking at > 2000 kW of cooling necessary for a 1.25m heatshield.

For perspective:

Wall outlets in the US are capped at around 1.6 kW

The official spec on the S9G reactor powering the Virginia-class submarines is 30,000 kW of peak power

Lithium-ion batteries store about 850 kJ/kg

Water's heat of vaporization is 2,257 kJ/kg

Given how most people peg 1 kW to be around 1 EC/sec, I have two main conclusions:

KSP batteries are hilariously underpowered by a factor of around 40.

Even assuming a generous 40 kW = 1 EC/sec, if you're aiming for realism, you'd want active cooling to draw 50 EC/sec to cool a 1.25m circle at peak load. That's... kinda brutal.

As Nertea has said before, there's all sorts of things wrong with the system in KSP including underpowered batteries. But rewriting the system is way out of scope of this mod.

5 minutes ago, captinjoehenry said:

Actually I am pretty sure that peak load is lower than the current setting.  As it stands at peak load in atmosphere for large spaceplanes it is 10s of thousands of EC/s.  Honestly it needs to be heavily reduced for it to really work.  Or at least adjusted a fair bit for the pure EC system to work for the other ones you are just running pumps to move a cooling fluid

Honestly the ablation factor currently was a wild guess. I expected it to be adequate for our purposes. I can knock it down for in a patch if it's really game-breaking. But any other system of cooling and a rebrand will be later.

 

 

[captinjoehenry]

Just now, Esquire42 said:

As Nertea has said before, there's all sorts of things wrong with the system in KSP including underpowered batteries. But rewriting the system is way out of scope of this mod.

Honestly the ablation factor currently was a wild guess. I expected it to be adequate for our purposes. I can knock it down for in a patch if it's really game-breaking. But any other system of cooling and a rebrand will be later.

 

 

It isn't a huge issue for my space plane as it is so over powered I was just able to slap on 10 more 3000EC/s nuclear power plants and it worked just fine.  For others it should probably be a bit lower.  I would have to test it with smaller planes to see what it is like with small planes but with big SSTO space planes it is a bit much.  Mind you it is fully adequate for reentry but hypersonic flight in atmosphere is prohibitive in its EC demand

[Esquire42]

1 minute ago, captinjoehenry said:

It isn't a huge issue for my space plane as it is so over powered I was just able to slap on 10 more 3000EC/s nuclear power plants and it worked just fine.  For others it should probably be a bit lower.  I would have to test it with smaller planes to see what it is like with small planes but with big SSTO space planes it is a bit much.  Mind you it is fully adequate for reentry but hypersonic flight in atmosphere is prohibitive in its EC demand

I haven't gotten to test it out yet honestly, still working and coming down from finals week. Let's both test it over the weekend in stock and see how we like it.

[captinjoehenry]

23 minutes ago, Esquire42 said:

I haven't gotten to test it out yet honestly, still working and coming down from finals week. Let's both test it over the weekend in stock and see how we like it.

Well I am honestly not sure how applicable this would even be to an unmodded game as the main region where this'll find use will be with really high mach speed planes which are not really possible in stock and especially for real scale system mods as the orbital velocity is so much higher if you don't have an ablator of some sort you are not going to survive reentry.  So for stock I don't think this'll be needed at all but it would definitely work wonders for modded installs like if you wanted to replicate the X15 with a high power engine then you'll need a mod like this to survive atmospheric heating.

[captinjoehenry]

Also found this mod that has an actively cooled heat shield that uses liquid fuel instead of ablator which is then vented over the side as an open loop active cooling system

 

[Esquire42]

21 hours ago, captinjoehenry said:

Well I am honestly not sure how applicable this would even be to an unmodded game as the main region where this'll find use will be with really high mach speed planes which are not really possible in stock and especially for real scale system mods as the orbital velocity is so much higher if you don't have an ablator of some sort you are not going to survive reentry.  So for stock I don't think this'll be needed at all but it would definitely work wonders for modded installs like if you wanted to replicate the X15 with a high power engine then you'll need a mod like this to survive atmospheric heating.

The thing is we have to balance this against something, so stock makes sense. Otherwise we have a bunch of competing standards.

[captinjoehenry]

That is true.  Still it might be best to balance it against a real scale system as that's where space planes are going to have the greatest need of something like this as they are pretty good at surviving more or less all stock scale reentry profiles 

[Esquire42]

Has anyone had any luck installing this through CKAN?

[linuxgurugamer]

On 12/14/2016 at 11:39 AM, Errol said:

Out of curiosity, is there any real world analogue of this? The shuttle used heat dissipating ceramic tiles, and they were a major factor in it's downfall. 

One of the last flights of the X-15 had ablative material on the entire plane.

6 hours ago, Esquire42 said:

Has anyone had any luck installing this through CKAN?

It's not yet available in CKAN, there's an error, I'll take care of it

[JadeOfMaar]

One of the mod ideas lingering in the back of my mind has been a thermal solution that uses Water or a superior liquid coolant, perhaps LqdNitrogen. But I couldn't create such a thing myself. I'm glad I got pointed to this thread. I encountered a modlet that adds Ablator generation to the stock ISRU to refill heatshields on-the-fly, and I've done some experimentation (though, with no success yet) to make Water and IntakeLqd resource useful outside of whatever niche mods may exist for them, and which fits into future plans in OP.

[Esquire42]

11 hours ago, linuxgurugamer said:

One of the last flights of the X-15 had ablative material on the entire plane.

It's not yet available in CKAN, there's an error, I'll take care of it

Thanks, I was just about to message you or @politas about it.

7 hours ago, JadeOfMaar said:

One of the mod ideas lingering in the back of my mind has been a thermal solution that uses Water or a superior liquid coolant, perhaps LqdNitrogen. But I couldn't create such a thing myself. I'm glad I got pointed to this thread. I encountered a modlet that adds Ablator generation to the stock ISRU to refill heatshields on-the-fly, and I've done some experimentation (though, with no success yet) to make Water and IntakeLqd resource useful outside of whatever niche mods may exist for them, and which fits into future plans in OP.

Honestly, the module for this mod isn't that clever. It's just some fiddling with the stock ablator module plus a MM patch to add the custom module to any part that provides lift. As for the liquid that will actually be used, any input is welcome. The trick will be trying to balance mass with resource consumption.

[linuxgurugamer]

It's now available in CKAN

[captinjoehenry]

Ok one thing that would be a nice feature would be the ability to blacklist some mods or specific items as some reentry capsules have lifting surface module to add more control but they already have an ablator installed.  So maybe just don't add the active ablation module to a part that already has an ablator module on it?

[linuxgurugamer]

Something I'd like to see is along these lines:

• Ablative material can be added to any surface, color would probably be white, and adds weight
• As it gets used, it slowly turns darker, and turns lighter
• Cannot be repaired, although a mechanism where a base could refurbish the vehicle would be nice

In my opinion, the whole idea behind ablative materials is that they burn up and away, thereby taking the heat away as they vaporize.  Electrical charge is, IMHO, a cheat, but I'm not going to fault anyone who uses it.  I won't, but that's fine.

Some of the issues I see are:

• How to add ablative material to one side of a part only
• How to change the surface texture of a part to show the ablative material

I would suspect that it would probably be easier to have a special procedural part which would be an ablator, and could be customized to the surface it is on.

[captinjoehenry]

Just now, linuxgurugamer said:

Something I'd like to see is along these lines:

• Ablative material can be added to any surface, color would probably be white, and adds weight
• As it gets used, it slowly turns darker, and turns lighter
• Cannot be repaired, although a mechanism where a base could refurbish the vehicle would be nice

In my opinion, the whole idea behind ablative materials is that they burn up and away, thereby taking the heat away as they vaporize.  Electrical charge is, IMHO, a cheat, but I'm not going to fault anyone who uses it.  I won't, but that's fine.

Some of the issues I see are:

• How to add ablative material to one side of a part only
• How to change the surface texture of a part to show the ablative material

I would suspect that it would probably be easier to have a special procedural part which would be an ablator, and could be customized to the surface it is on.

Actually what this represents is running a coolant through the part to deal with the heat of reentry.  There have been multiple plans to do this but they were never completed due to a variety of reasons but mostly due to complexity.  This system allows you to use just a metal heat shield which you pump a coolant through to deal with the heat of reentry.  So if you are using a closed loop cooling system you would in theory be able to go through the atmosphere at very very high speeds indefinitely or as long as the pumps for the cooling system can be powered.  

As such active ablation probably is not the correct name for what this is as it really represents an active cooling system to deal with the heat of reentry instead of heavy non refreshable ablator material.  

[Randazzo]

4 minutes ago, captinjoehenry said:

As such active ablation probably is not the correct name for what this is as it really represents an active cooling system to deal with the heat of reentry instead of heavy non refreshable ablator material.  

http://forum.kerbalspaceprogram.com/index.php?/topic/142505-12-active-heat-management-system-031/

Sounds familiar.

[linuxgurugamer]

2 minutes ago, Randazzo said:

http://forum.kerbalspaceprogram.com/index.php?/topic/142505-12-active-heat-management-system-031/

Sounds familiar.

yes, but that mod can't deal with the heat of reentry, at least not the way it is

[Randazzo]

4 minutes ago, linuxgurugamer said:

yes, but that mod can't deal with the heat of reentry, at least not the way it is

It could if you used it like a heatshield, but that's neither here nor there.

P.S.- I wasn't complaining.

Edited December 22, 2016 by Randazzo

[captinjoehenry]

Ok I have the fixxed the patch so that if a part already has an ablator system on it it will not gain an active ablation module here is the code:

@PART:HAS[@MODULE[ModuleLiftingSurface],!MODULE[ModuleAblator]]:Final
{
	MODULE
	{
		name = ModuleAblator
		ablativeResource = ElectricCharge
		lossExp = -750
		lossConst = 0.1
		pyrolysisLossFactor = 6000
		reentryConductivity = 0.01
		ablationTempThresh = 500
		
	}
}

 

[Esquire42]

9 hours ago, captinjoehenry said:

Ok I have the fixxed the patch so that if a part already has an ablator system on it it will not gain an active ablation module here is the code:

@PART:HAS[@MODULE[ModuleLiftingSurface],!MODULE[ModuleAblator]]:Final
{
	MODULE
	{
		name = ModuleAblator
		ablativeResource = ElectricCharge
		lossExp = -750
		lossConst = 0.1
		pyrolysisLossFactor = 6000
		reentryConductivity = 0.01
		ablationTempThresh = 500
		
	}
}

 

Let me play around with this. I don't plan on pushing another update until I include the ability to toggle on and off. Are there that many parts that contain both ModuleLiftingSurface and ModuleAblator?

 

11 hours ago, linuxgurugamer said:

Something I'd like to see is along these lines:

• Ablative material can be added to any surface, color would probably be white, and adds weight
• As it gets used, it slowly turns darker, and turns lighter
• Cannot be repaired, although a mechanism where a base could refurbish the vehicle would be nice

In my opinion, the whole idea behind ablative materials is that they burn up and away, thereby taking the heat away as they vaporize.  Electrical charge is, IMHO, a cheat, but I'm not going to fault anyone who uses it.  I won't, but that's fine.

Some of the issues I see are:

• How to add ablative material to one side of a part only
• How to change the surface texture of a part to show the ablative material

I would suspect that it would probably be easier to have a special procedural part which would be an ablator, and could be customized to the surface it is on.

This reminds me of the Active Ablation/Active Balanced Cooling discussion from a while back. I definitely see a place for procedural ablation surfaces, such as heat titles. Perhaps a small tweakscale-able heat tile model would serve this purpose well, or perhaps several models based on wing segment pieces. 

So this mod would consist of a few components:

• Heat tiles
• Open-loop in-wing cooling
• Closed-loop in-wing cooling
• Electric cooling, like we have now.

I have blender, a heat tile or two wouldn't be terrible to make. I'm slightly wary of procedural parts right now, though. I'd feel more comfortable once I get the rest of the timeline in a decent shape. I'll add the heat tiles to it too though. Great suggestion.

As for replenishment, the easy way to do this would be to create a super expensive storage bin for the ablator material and have the Convert-O-Tron be able to produce it for a ludicrous amount of ore/electric charge (or maybe incorporate EL into it. I haven't used EL in a while, does it auto-fill ablator or are you screwed?)

11 hours ago, Randazzo said:

http://forum.kerbalspaceprogram.com/index.php?/topic/142505-12-active-heat-management-system-031/

Sounds familiar.

You've got me interested. I'll have to check this out. I already use Heat Control. 

 

 

I have a conference paper that I need to finish by the first week of January, but I should be able to push out a release that allows you to turn the ablator on and off.

[Randazzo]

@Esquire42, first let me put this disclaimer up here: I haven't actively developed anything heat related in a long time now, so some of my information may be out of date. The definitive man to ask is @NathanKell if he's lurking about and feeling generous.

A couple of issues you're going to face:

• Heat tiles - radially mounted (which is anything not stack mounted) parts do not (or did not) occlude their parent part from airflow.
•  I believe (possibly incorrectly) that using electric charge as your sole ablative resource will result in no heat being lost as the EC "ablates", because EC has an undefined specific heat, or it is 0.

Heat Control uses a plugin written by Nertea, which is certainly an avenue you could look at if you have the chops for it. I didn't.

Active Heat Management is a hatchet job on stock modules, but by all means use anything you find useful. The comment I made was just about the name and that particular sentence I quoted.

[captinjoehenry]

8 hours ago, Esquire42 said:

Let me play around with this. I don't plan on pushing another update until I include the ability to toggle on and off. Are there that many parts that contain both ModuleLiftingSurface and ModuleAblator?

 

This reminds me of the Active Ablation/Active Balanced Cooling discussion from a while back. I definitely see a place for procedural ablation surfaces, such as heat titles. Perhaps a small tweakscale-able heat tile model would serve this purpose well, or perhaps several models based on wing segment pieces. 

So this mod would consist of a few components:

• Heat tiles
• Open-loop in-wing cooling
• Closed-loop in-wing cooling
• Electric cooling, like we have now.

I have blender, a heat tile or two wouldn't be terrible to make. I'm slightly wary of procedural parts right now, though. I'd feel more comfortable once I get the rest of the timeline in a decent shape. I'll add the heat tiles to it too though. Great suggestion.

As for replenishment, the easy way to do this would be to create a super expensive storage bin for the ablator material and have the Convert-O-Tron be able to produce it for a ludicrous amount of ore/electric charge (or maybe incorporate EL into it. I haven't used EL in a while, does it auto-fill ablator or are you screwed?)

You've got me interested. I'll have to check this out. I already use Heat Control. 

 

 

I have a conference paper that I need to finish by the first week of January, but I should be able to push out a release that allows you to turn the ablator on and off.

There are no stock parts that have ablator and a lifting surface but some mods do add parts with both of those.  The one example I have right now is ModPods that has heat shields for capsules and they also produce lift.  That is rather useful as it allows some control over the reentry profile and adding the active ablator to it really screws you over.  That is the main reason I made the modification to it.  Also mods that add the space shuttle tend to have ablator on their parts which also produce lift.

So while it is not hugely common it is definitely important.

Also the open and closed loop cooling should just be using the fuel on the space craft or some cooling liquid.  So for closed loop cooling you shouldn't be losing any of it and for open loop you would be losing some.  If it is some special cooling fluid it shouldn't be too terribly difficult to replenish with an ISRU.  But replenishing normal ablator definitely should be quite costly.

[Esquire42]

8 hours ago, Randazzo said:

@Esquire42, first let me put this disclaimer up here: I haven't actively developed anything heat related in a long time now, so some of my information may be out of date. The definitive man to ask is @NathanKell if he's lurking about and feeling generous.

A couple of issues you're going to face:

• Heat tiles - radially mounted (which is anything not stack mounted) parts do not (or did not) occlude their parent part from airflow.
•  I believe (possibly incorrectly) that using electric charge as your sole ablative resource will result in no heat being lost as the EC "ablates", because EC has an undefined specific heat, or it is 0.

Heat Control uses a plugin written by Nertea, which is certainly an avenue you could look at if you have the chops for it. I didn't.

Active Heat Management is a hatchet job on stock modules, but by all means use anything you find useful. The comment I made was just about the name and that particular sentence I quoted.

From the testing @captinjoehenry has done, it looks like the second point isn't the case. But thanks for the heads up about airflow occlusion. As for AHM, I was mainly thinking about adding it to my modded career. I might take a look at how you handle it and incorporate some parts, with your permission of course.

 

6 hours ago, captinjoehenry said:

There are no stock parts that have ablator and a lifting surface but some mods do add parts with both of those.  The one example I have right now is ModPods that has heat shields for capsules and they also produce lift.  That is rather useful as it allows some control over the reentry profile and adding the active ablator to it really screws you over.  That is the main reason I made the modification to it.  Also mods that add the space shuttle tend to have ablator on their parts which also produce lift.

So while it is not hugely common it is definitely important.

Also the open and closed loop cooling should just be using the fuel on the space craft or some cooling liquid.  So for closed loop cooling you shouldn't be losing any of it and for open loop you would be losing some.  If it is some special cooling fluid it shouldn't be too terribly difficult to replenish with an ISRU.  But replenishing normal ablator definitely should be quite costly.

Hm. Well it's not a major modification so that seems acceptable. But I'm still not going to push it out until I get the darn thing to toggle