[1.12.*] Deadly Reentry v7.9.0 The Barbie Edition, Aug 5th, 2021

[Wanderfound]

Thanks for the reply Starwaster, yes I suspect you're right, I really need to modify my approach both in flight and in the build.

The reason I was getting to very high speed before shooting for orbit was really just down to the fuel consumption of the rapier in closed cycle mode.

I suppose I'll have to put more fuel on and switch earlier.

No, you really don't. Once you get over 30,000m, you should be able to do any speed you like without worrying about heating, and below 30,000m you'll be fine so long as you're out of the hypersonic.

The exact profile will depend on the plane, but a 30° ascent to 15,000m followed by a flat accelerating climb to around 35,000m works for most things. You shouldn't be burning any oxidiser until the jets choke, and they should be doing that at about Mach 5 / 35,000m.

See the second post in the Kerbodyne thread in my sig for a piloting guide. Also see http://forum.kerbalspaceprogram.com/threads/54954-0-25-Deadly-Reentry-v6-2-1-Oct-12-2014?p=1500490&viewfull=1#post1500490 for reentry tips.

Edited November 2, 2014 by Wanderfound

[MartGonzo]

Thanks taniwha and Wanderfound,

I'll have to experiment a bit to see how high I can get before running out of air but waiting until at least 30 and a smooth flat ascent seems like good advice

Thanks again

[Starwaster]

Progress report:

Ok, so I know I said I was going to try to push an update out over the weekend and obviously I'm still working on that. I'm starting to get things to where I think they ought to be at least for Normal mode. A bit of warning, it's going to be a little bit deadlier, even for stock sized Kerbin. I still have to test it without any drag modifiers. (no FAR, no NEAR, no SDF).

Here's some of the more prominent changes (aside from the toolbar and difficulty settings)

First, know that these still aren't engraved in stone!

I'm still doing some test flights to be sure that things are still flyable without being too hard. I don't want my RCS engines burning off anymore than you guys do. And I want my spaceplanes to be able to make it to orbit without incinerating themselves! So if these numbers go into production then it means I can do launches and reentry without dying, and so can you!

SO:

1: Max temperatures are being slashed across the board for everything except heat shields and engines. The new max temperature on parts is 700 degrees. I based that on the melting point of aluminum but gave it a bit of a safety buffer for playability

Heat shields have long had a hard coded exemption that prevented them from being reduced and I added a similar case for engines. Engines won't be cut unless they are over ~1400. (based on steel's melting point but buffed a little)

Those maxes are actually per difficulty level so Easy will have higher tolerances. (except that I think it will require a game restart for that to go into effect, or at a bare minimum, exit to main menu might be enough)

What it means for ascent and reentry:

No shallow launches! That's really always been true but now just a little more so. If your flight path during ascent is too shallow then you'll be going too fast when you're too low in the atmosphere and you'll burn bits off. But it's still quite doable to get to orbit whether you're using RSS, FAR or whatever.

2: Density coefficient is dropping from 0.85 to 0.8 for normal. Easy will keep it at 0.85 or possibly raised. (I don't think it really needs raising but... it's on the table). Hard will likely see it lowered. (haven't really committed to that but I'm looking at a value of 0.5 - 0.7).

What it means:

Things will get hotter faster. During reentry you'll see hotter temperatures at higher altitudes. For a stock Kerbin reentry that will mean peak reentry heating at 45-50 km depending on if it's an LKO or return from Münar space. (haven't tested with a Minmus return but I'd expect it to be a bit hotter.

For Real Solar System, that will result in reaching peak heating at about 70km (which is about right for real life)

Easy Mode: Parachutes will be more durable by about two times as much as they currently are. Kerbals will be more resistant to g-forces.

Heat shields: I'm looking at making these scale up in efficiency when using them with Real Solar system without having to download separate shields. This shouldn't affect the current RO shield download.... much.... or at all hopefully.

I'm probably forgetting something, but that's the important stuff I think....

Some minor stuff: Some data that is currently persistent no longer is. This means that if certain config file data is changed, those changes will now apply to saved games. (for example, certain heat shield stats such as loss / dissipation. Currently if those are changed, existing craft don't have those changes applied. Now, they will)

Edit: Oh, chutes. Chutes will be patched so that their default values are safe®. Kerbin is the benchmark for those values (which is true even in Stock KSP)

Edit #2: And chutes in cone housings will have weak heat shielding (reflective only, 0.1) so if they're acting as nose cones on the tops of rockets, they'll provide some protection against heating. BUT, only if they haven't been deployed at all. As soon as the cap has blown they're open, just as they should be.

Edited November 2, 2014 by Starwaster

[NathanKell]

That all sounds most excellent to me.

On a ballistic reentry from LEO, peak heating on RSS should be about 50km with density exponent of 0.5 (i.e. real life).

As for heat shield patching, here is a MM patch I just wrote for 6.4x Kerbin if you need ideas:

// Wildcard
@PART[*]:HAS[@MODULE[ModuleHeatShield]]:WHATEVER_PASS
{
	@maxTemp = 1800
	@MODULE[ModuleHeatShield]
	{
		@loss
		{
			@key,1 ^= :^1000 ::
			@key,1 ^= : 0 0::
			@key,1 *= 3
			@key,1 ^= :$: 0 0:
			@key,1 ^= :^:2500 :

			@key,2 ^= :^3000 ::
			@key,2 ^= : 0 0::
			@key,2 *= 5
			@key,2 ^= :$: 0 0:
			@key,2 ^= :^:7500 :
		}
		@dissipation
		{
			@key,1 ^= :^500:400:
		}
	}
}

[Wanderfound]

Yay for DRE updates, with the caveat that hopefully it won't slow down spaceplane reentry too much; it's already a fairly drawn-out process. As well as not wanting RCS units to burn off, I'd also like to keep my hardpoints intact; the limitations of stock landing gear result in a lot of planes on stilts.

[Starwaster]

That all sounds most excellent to me.

On a ballistic reentry from LEO, peak heating on RSS should be about 50km with density exponent of 0.5 (i.e. real life).

As for heat shield patching, here is a MM patch I just wrote for 6.4x Kerbin if you need ideas:

Although I personally can handle 0.5, it's difficult enough that I can't help thinking most of DRE's users would find it too painful. Though it could maybe go in Hard mode. I seem to recall it was set to that before and there was much weeping and gnashing of teeth

Yay for DRE updates, with the caveat that hopefully it won't slow down spaceplane reentry too much; it's already a fairly drawn-out process. As well as not wanting RCS units to burn off, I'd also like to keep my hardpoints intact; the limitations of stock landing gear result in a lot of planes on stilts.

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Challenges/Akademy%20Awards/Kerbodyne%20Endeavour/screenshot414_zps70489df4.jpg

Have you tried B9's landing gear? Even if you keep nothing else from B9, it's worth it for the landing gear. (and the air brakes. And that.... short squat engine thing.... and the S2 cargo bay that I made an S2->Mk2 adapter for Porkjet's SpaceplanePlus...)

Edited November 3, 2014 by Starwaster

[NathanKell]

Starwaster, I mean in conjunction with lowering the heat multiplier and/or buffing shields. Not *only* changing the exponent.

[ArcFurnace]

Some information on various materials intended for use at high temperatures:

Melting point information is easy to find. However, most metals fail quickly at temperatures well under their melting points due to reduction in strength and/or creep (typically becoming a problem above one-half their melting point, measured in Kelvin). The Space Shuttle Orbiter's aluminum structure had a maximum survivable temperature of only 175 °C; it dealt with reentry heating using various sorts of high-performance insulation that prevented the heat from reaching the structure (ref).

Titanium alloys for high-temperature use are lightweight and strong. Up to ~800 °C is survivable but decreasing operating temperatures increases allowable stress and/or material lifetime (almost all high-temperature materials have this behavior) (ref). Density is 4.6 g/cc. Your choice of 700 °C as a maximum temperature for most parts is nicely consistent with titanium alloy as the default air-facing structural material.

Steels (typically stainless steels due to the necessity of corrosion resistance at high temperatures) are denser than titanium and have equivalent or worse strength at 600 °C (ref).

Nickel-based "superalloys" are expensive, complex to manufacture, and very dense, but produce impressive high-temperature performance. Modern superalloys can survive temperatures of up to 1200 °C (more than 80% of their melting temperatures) and still maintain some strength (ref). Density is ~9 g/cc, almost twice that of titanium. As mentioned before, reduction of required operating temperatures improves performance.

Various sorts of ceramics can have higher operating temperatures, lower densities, or both, but have a nasty habit of being brittle and easy to damage.

Reinforced carbon-carbon has sufficient strength for structural use and can survive temperatures of 1500 °C - 2000 °C (the RCC on the Space Shuttle Orbiter leading edges was rated for 1500 °C). Its density is ~2 g/cc. However, it is somewhat brittle and lacks impact resistance; Space Shuttle Columbia was destroyed after a chunk of foam insulation falling off of the external tank smashed a hole in one of its wing-edge RCC panels. If debris strikes can be avoided, it is a very effective (and very expensive) heat shielding material.

The "high-temperature reusable surface insulation" tiles that covered the rest of the bottoms of the Space Shuttle Orbiters can survive temperatures of up to 1250 °C, have an impressively low density of only 0.14 g/cc, and are incredibly insulating. However, they pay for this by having essentially zero structural strength; the low density and insulating effect is achieved by being a "foam" of 94% air/6% silica fiber. They must be mounted onto some other structural material (although due to their insulation value, temperature resistance is no longer a concern for said structural material), and they must be mounted as small individual tiles to allow for flexure of the underlying structure without shattering (ref).

The currently-under-development Skylon spaceplane is supposed to use carbon-fiber reinforced plastic structural members and aluminum propellant tankage, with a lightweight, insulating fiber-reinforced ceramic aeroshell to keep heat away from the very heat-sensitive internal structure. Details on the exact nature of the planned ceramic aeroshell are not present.

--------------------------------------

Not sure what a reasonable MaxTemp is for engines. The combustion gases and rocket exhaust are extremely hot, but the combustion chamber and rocket nozzle are generally cooled by fuel flow (or some other cooling method) and never actually reach those temperatures. Also, if it's too high, rocket engines can be used as impromptu "heat shields", which may or may not be desirable from a gameplay standpoint. 1400 °C is probably a good starting point for now, just remember to adjust heat generation rates if necessary to ensure that certain engines don't become guaranteed explosions (I'm looking at you, Mainsail).

[Wanderfound]

<good info about thermal resistance>

As hinted at in my hardpoint comment, though, some allowance needs to be made for the KSP construction process. A real spaceplane can stash its landing gear away behind the heat shielding; a KSP spaceplane can't. Ditto for assorted other small radially attached bits.

[ArcFurnace]

As hinted at in my hardpoint comment, though, some allowance needs to be made for the KSP construction process. A real spaceplane can stash its landing gear away behind the heat shielding; a KSP spaceplane can't. Ditto for assorted other small radially attached bits.

Hmm, yes, a good point. The most obvious way of dealing with it is adding non-ablative heat shields and increased MaxTemp to all parts that need it and could reasonably be expected to have it, exempting them from the hard cutoff. For example, Small Gear Bays already have a 25% reflective heat shield and MaxTemp = 1800 °C in current Deadly Reentry; this could be kept in the new version, implying a protective insulating shell of RCC around the gear bays. Starwaster will have to decide on appropriate values for the various parts that are currently heat-shielded (Mk2 cockpits/fuselages, wings, and such), and whether shields need to be added to any other various bits and pieces.

Fairings or nose cones might also turn out to be more important for rocket ascent, to protect delicate vacuum-rated equipment and such not designed to survive exposure to a hypersonic airstream. On the way down, of course, we already have heat shields.

Edited November 4, 2014 by ArcFurnace

[Starwaster]

A real spaceplane can stash its landing gear away behind the heat shielding; a KSP spaceplane can't. Ditto for assorted other small radially attached bits.

Yes they can.

Do we need some configs that do that? I hadn't thought about landing gear in awhile.....

I'll try to sneak it into this update.

Oops they already have them... Oops again, ArcFurnace commented on that. Are you talking about someone else's landing gear? B9 or something?

Edited November 4, 2014 by Starwaster

[camlost]

I think setting maxtemp of all parts to a certain level is not so good. The best thing I can think of is to use tweakables to allow users to set the max temp.

Also I think DRE should ignore engines in total. Engines have their own heating model, which is linked with visual effects. Messing with this causes too much problems

[Wanderfound]

Yes they can.

Do we need some configs that do that? I hadn't thought about landing gear in awhile.....

I'll try to sneak it into this update.

Oops they already have them... Oops again, ArcFurnace commented on that. Are you talking about someone else's landing gear? B9 or something?

No, discussing stock.

Yes, I know that the gear bays have uprated heat shielding so that they won't burn off when retracted; it was more of a rhetorical than literal example. But the basic point stands: there are assorted parts (RCS units etc) that the KSP build process requires you to leave hanging in the wind more than they would be in reality, and it is good when DRE takes account of that difference.

[NathanKell]

You really shouldn't be placing RCS on the underside of your plane anyway. It's perfectly possible to get enough RCS authority while keeping all RCS parts shielded by the fuselage/wings.

Structural pylons, however, should probably be treated like wings are, since they're squat little wings.

[Jovus]

I have a use question! Not a bug question!

I'm using RealChutes with Deadly Reentry. As such, if I deploy my parachutes while going too fast, I tend to die. This is as it should be.

My question is, how do I properly use drogue chutes? My impression is that drogue chutes are intended to slow down your craft so that the main chutes can properly deploy. However, as far as I can tell, drogue chutes are just as easy to rip off as main chutes, so I'm struggling to see a use case.

Is it the case that drogue chutes in fact can survive higher speeds? Am I doing chute deployment incorrectly? Am I right, and drogue chutes really are extremely niche to useless with this version of DRE? Can anyone give me some tips?

[NathanKell]

Drogue chutes are intended to slow your craft from ~250m/s to ~50m/s, at about 5km. Since main parachutes have the whole "semi-deployed" thing, and don't (ingame) rip to shreds more easily than drogues, means that drogues are less useful.

[Jovus]

Thanks. I suppose I'll just ignore drogues, then. One other question that brings up, though, more to the root of what I was trying to do:

How do you keep sounding rockets from dying? Specifically, I mean rockets intended to go on steep suborbital curves for science-gathering or other purposes.

If the answer is "you don't; use a shallower trajectory," that's OK.

[Starwaster]

IRL, Apollo deployed its drogues at ~7 km which is consistent with what we've been telling people for the most part. 7km is USUALLY safe, but YMMV.

drogue = 24,000 feet = 7317 meters

mains = 10,000 feet = 3048 meters

Edited November 4, 2014 by Starwaster

[jpkerman]

IRL drogue chutes are also used to stabilize or orient an attached payload. Technically there should be some risk or discomfort to the crew by deploying main chutes if the capsule is at a tilt from a lifting reentry but the game does not address that beyond gee force on the crew.

[jandcando]

Does this mod change the max temps of asteroids? It would be good if we could use them as heat shields (no ablative resource, just high maxTemp). Otherwise, how could we bring one down to Kerbin?

[Starwaster]

Does this mod change the max temps of asteroids? It would be good if we could use them as heat shields (no ablative resource, just high maxTemp). Otherwise, how could we bring one down to Kerbin?

Asteroids are not accorded any special status and will burn up like anything else. I suggest constructing an attachment using the grabber device with a heat shield at one end and radial parachutes or Real Chute's stack mounted (non-cone) chute.

Or even using grabber arms, one with a heat shield and the other a chute.

[SmarterThanMe]

Asteroids are not accorded any special status and will burn up like anything else. I suggest constructing an attachment using the grabber device with a heat shield at one end and radial parachutes or Real Chute's stack mounted (non-cone) chute.

Actually, this gives me a great idea for a mod - an E Class object re-enters, burns and devolves in a D Class, which devolves into a C and so on.. So smaller asteroids burn up completely in the atmosphere, bigger ones fall through.

If I were clever enough, I'd do this myself. But I'm not. See my name.

[Starwaster]

Actually, this gives me a great idea for a mod - an E Class object re-enters, burns and devolves in a D Class, which devolves into a C and so on.. So smaller asteroids burn up completely in the atmosphere, bigger ones fall through.

If I were clever enough, I'd do this myself. But I'm not. See my name.

Oh... I thought maybe you were a composite being, with one part of you being smarter than the other part....

[SmarterThanMe]

Oh... I thought maybe you were a composite being, with one part of you being smarter than the other part....

Heh. No. That's in reference to my (real life) work. I "teach" kids who are smarter than me.

[Lei07]

Hi! Firstly, just want to say I highly enjoy DRE, it adds realism and difficulty to the game, and makes a nice companion to FAR/NEAR, which is sort of what my question is all about.

A few days ago I finally updated my modded build to KSP 0.25, fresh install, all updated mods, and a new Interstellar mod based save game. Working with basic tech I'm at the stage of returning from orbits of about 100km - 300km, but always using 100km as a parking/transfer orbit, before doing returns from moons.

I've had some aerobraking issues which I've requested help with in the FAR forum, as FAR has been altered for the latest version of the game, but through a bit of trial and error, I may have found a bug relating to the heatshiled for the Mk1 Pod.

I was on Skype with a friend, using a near identical craft, returning from a near identical orbit with a 20km periaps, with one difference, he did not use DRE, and as such, I neglected to add a heatshield. I was expecting sparks but I was infact rewarded with a nice safe landing, more akin to how FAR for KSP 24.2 was for me.

He then added the DRE mod, got the MK1 Pod, added a heatshield and then started having the issues I was suffering. He then suggested that the drag vector could be accidently "inverted", so you are infact slightly accelerating during the intial stages of reentry and thus coming in alot faster in the lower atmosphere and making a nice green splat on the ground.

I'm happy to post log files etc if required, once I figure out how Just wondered if anyone could confirm this, or if this has already been adressed, I did scan the last few pages of this thread, and the patchnotes, but didn't spot anything.