1.0.5 Reentry drag and heat

[aluc24]

I've been playing KSP 1.0.4 for a while now, and launched at least 50 missions, so I got pretty much used to the way things work in it. So when I installed 1.0.5, I immediately noticed that drag and heat have been reworked.

Namely, having a capsule on a suborbital trajectory (not even reaching 40km apoapsis) will make it reach ground in speed too high to deploy chutes. Before 1.0.5, I used to do all kind of suborbital hops around Kerbin, but now, it is impossible without drogue chutes, which aren't available in early tech tree. So it appears that drag values have been decreased.

Also, it seems that parts now generate much more heat upon reentry. As I tried to reenter with small capsule with a science bay and heat shield attached to it from a 71x71km orbit to 71x25, it exploded due to high temperatures.

Anyone else noticed this? BTW, I'm not using Deadly Reentry or any related mods.

[Arkafold]

I have actually been having the same issues. I just started playing again two weeks ago and got some early tech on Normal career. I could get into orbit and back(barely). Since 1.0.5. I can't even get back safely to Kerbin with 35-45km Apoapsis

[aluc24]

I have actually been having the same issues. I just started playing again two weeks ago and got some early tech on Normal career. I could get into orbit and back(barely). Since 1.0.5. I can't even get back safely to Kerbin with 35-45km Apoapsis

Try it Hard, like me

[Vegetal]

I started a new career game, and the differences are noticeable. That said, with standard Mk1 capsule ships, I can safely reenter with no heatshield from LKO, but when coming from a little more than that, a heatshield becomes almost a necessity (which is a good thing, they were almost useless). I take a lot of ablator off though, 40 or 50 seems enough for Kerbin, even coming from Minmus.

Where I'm finding more difficulty though is the ascent. The ideal profile I did before is not possible anymore. It involved a very shallow angle, now you fry easily when doing that, so I've been using a more conservative gravity turn. Spaceplanes seem to have been quite affected also, didn't test much.

[aluc24]

I started a new career game, and the differences are noticeable. That said, with standard Mk1 capsule ships, I can safely reenter with no heatshield from LKO, but when coming from a little more than that, a heatshield becomes almost a necessity (which is a good thing, they were almost useless). I take a lot of ablator off though, 40 or 50 seems enough for Kerbin, even coming from Minmus.

Where I'm finding more difficulty though is the ascent. The ideal profile I did before is not possible anymore. It involved a very shallow angle, now you fry easily when doing that, so I've been using a more conservative gravity turn. Spaceplanes seem to have been quite affected also, didn't test much.

It'd be great if someone could document these changes, because it throws away a lot of what we knew about KSP aerodynamics up to now...

[Streetwind]

Make sure you updated to build 1028 (see announcement forum) there was a bug with missing body lift in initial 1.0.5.

[LostOblivion]

Well, they changed how ablation works. In 1.0.4 rate of ablation was based on the amount of ablator LEFT, while in 1.0.5 it is based on the total possible alator for the heat shield, with no respect to how much remains.

The practical result is that heat shields ablate more quickly now, though this also means more cooling effect due to using more ablative material.

[panzer1b]

It'd be great if someone could document these changes, because it throws away a lot of what we knew about KSP aerodynamics up to now...

Now dont take my word for it as its just what i experienced flying 1.0.4 crafts in 1.0.5, but the following are my observations:

Heating is WAY higher then before, especially in the old acceleration zone for spaceplanes/SSTOs. That means that between 15 and 30km you will burn if you go too fast, and the absolute maximum speed ive pulled off before i fried on jets alone was 1500m/s, you CANNOT exceed that or you simply get fried in your burning cockpit regardless of how well the vessel itself is built. In the past, my SSTOs would exceed 1650m/s at ~17km before i kick in rockets with no major heat problems (provided you didnt have exposed junk below 2000K tolerance), now, those same vessels burn at 1500m/s or even lower.

Drag seems to have decreased at lower speeds, and increased at higher speeds. For one, breaking mach1 seems to be much easier with more draggy craft. In the past, i often needed to dive to bream mach1, now, i break it at 10 degree pitch up angle. That said, i seem to have more drag above 30km then in the past, which does cut down my rocket mode dV by enough to be noticable.

Overall, these 2 changes have made spaceplanes and SSTOs suffer quite a bit in terms of dV to orbit (and thus dV after reaching orbit). Im not going to get into teh discussion of whether this is good, bad, realistic, fun, ect, but the fact stands, that without abusing some bugs, vessels cannot reach as high speeds down low safely, and seem to be exposed to more drag at high speeds in the sortof transition zone (between 20 and 40km) then before.

Edited November 11, 2015 by panzer1b

[aluc24]

Make sure you updated to build 1028 (see announcement forum) there was a bug with missing body lift in initial 1.0.5.

Just updated to 1028. I'm not sure, but it seems drag increased a little.

Now dont take my word for it as its just what i experienced flying 1.0.4 crafts in 1.0.5, but the following are my observations:

Heating is WAY higher then before, especially in the old acceleration zone for spaceplanes/SSTOs. That means that between 15 and 30km you will burn if you go too fast, and the absolute maximum speed ive pulled off before i fried on jets alone was 1500m/s, you CANNOT exceed that or you simply get fried in your burning cockpit regardless of how well the vessel itself is built. In the past, my SSTOs would exceed 1650m/s at ~17km before i kick in rockets with no major heat problems (provided you didnt have exposed junk below 2000K tolerance), now, those same vessels burn at 1500m/s or even lower.

Drag seems to have decreased at lower speeds, and increased at higher speeds. For one, breaking mach1 seems to be much easier with more draggy craft. In the past, i often needed to dive to bream mach1, now, i break it at 10 degree pitch up angle. That said, i seem to have more drag above 30km then in the past, which does cut down my rocket mode dV by enough to be noticable.

Overall, these 2 changes have made spaceplanes and SSTOs suffer quite a bit in terms of dV to orbit (and thus dV after reaching orbit). Im not going to get into teh discussion of whether this is good, bad, realistic, fun, ect, but the fact stands, that without abusing some bugs, vessels cannot reach as high speeds down low safely, and seem to be exposed to more drag at high speeds in the sortof transition zone (between 20 and 40km) then before.

Great, thank you! Any ideas for good deorbit/interplanetary aerobrake altitudes?

[Scarecrow88]

Overheating issues on the way up as well as coming down now have killed this update for me. I'm going back to 1.0.4

[Nansuchao]

I think we all must learn the new altitudes for aerobraking. In 1.0.4 it was almost impossible to aerobrake on Eve or Jool, and not so important to aerobrake at Duna and Laythe. Btw in 1.0.5 the tweaked the atmospheric drag and SQUAD stated that it will be possible to aerobrake. Nevertheless I don't think that an aerobrake maneuver coming from interplanetary space will be a safe way to save Delta/V.

[Foxster]

I think we all must learn the new altitudes for aerobraking. In 1.0.4 it was almost impossible to aerobrake on Eve or Jool, and not so important to aerobrake at Duna and Laythe. Btw in 1.0.5 the tweaked the atmospheric drag and SQUAD stated that it will be possible to aerobrake. Nevertheless I don't think that an aerobrake maneuver coming from interplanetary space will be a safe way to save Delta/V.

I've tried every-which-way to aerobrake at Eve at any kind of SOI arrival speed and the craft just explodes every time.

[Pthigrivi]

Thats a shame. I haven't gotten around to testing this. What have you tried design wise? Is the atmosphere height the same?

In general I will say I've found re-entry pretty unforgiving in 1.0.5. I've finally got it down but definitely had to re-adjust my angle's of attack and descent for spaceplanes.

[Snark]

Here's what I've noticed about 1.0.5 reentry:

The scenario: Small 1.25m ship with a mass of around three tons. Orbiting Kerbin at LKO speeds (no high-speed interplanetary), reentering on a shallow trajectory (Pe around 40km).

In 1.0.4: such a craft would re-enter without a heat shield and it would be just fine. If I did add a heat shield, it would ablate away a fair chunk of the shield.

In 1.0.5: without a heat shield, the craft very quickly explodes while still well over 40km altitude. With a heat shield, it reenters and lands just fine... but it ablates away a remarkably small amount of the heat shield.

So it seems to me that either heat shields got a lot better, or everything else got a lot worse, or both.

[NathanKell]

Aerobraking at Eve is very possibly. Aerocapturing requires good heat shielding and a high drag-to-mass ratio.

[Warzouz]

Airbrakes have been nerfed though. They can't really be used for increase drag on reentry.

[Nansuchao]

I've tried every-which-way to aerobrake at Eve at any kind of SOI arrival speed and the craft just explodes every time.

From an Interplanetary transfer it will be obvious impossible, unless you have the perfect ship for that. But in 1.0.4 it was really dangerous to touch the Eve atmosphere also from a very low circular orbit.

[Greenfire32]

Yeah Aerocapturing is pretty much impossible now unless you manage heat like a boss, but Aerobraking still seems perfectly feasible.

[Reactordrone]

Here's what I've noticed about 1.0.5 reentry:

The scenario: Small 1.25m ship with a mass of around three tons. Orbiting Kerbin at LKO speeds (no high-speed interplanetary), reentering on a shallow trajectory (Pe around 40km).

In 1.0.4: such a craft would re-enter without a heat shield and it would be just fine. If I did add a heat shield, it would ablate away a fair chunk of the shield.

In 1.0.5: without a heat shield, the craft very quickly explodes while still well over 40km altitude. With a heat shield, it reenters and lands just fine... but it ablates away a remarkably small amount of the heat shield.

So it seems to me that either heat shields got a lot better, or everything else got a lot worse, or both.

Unshielded reentry seems ok unless your ship gets sideways or prograde during the reentry and then it explodes rapidly at lower speeds and higher altitudes than they did in 1.0.4. I had a mk1 pod explode on ascent doing 1370m/s at 17km so it looks like the pods have lost any kind of TPS on the front end.

[322997am]

Also what's the max height for air intakes now? That will be very useful for ssto fans.

- - - Updated - - -

And this will affect the accelerations zone for sstos

[Guest]

When I first started with 1.05, I was using just the mk1 command pod and whatever else was available in the early career. The materials bay was exploding every time during reentry. So, I started doing eva's to get out and gather all the data before reentry. No big deal, just loosing funds from not being able to recover the materials bay or goo cannisters. But now that I've started using the mk1 cockpit and crew cabin, I have yet to find a way to reenter with a spaceplane without blowing up. I've been trying for about 12 hours now and have yet to find a way to reenter with a mk1 cockpit based spaceplane. Mk1 cockpit explodes every single time. The reentry heat is borked, plain and simple. Unless of course the goal is to exclude all mk1 ssto designs at default normal difficulty, then it works fabulously. I am not having fun with this. Will be turning the heating system down from now on.

Edited November 12, 2015 by Otis

[Pthigrivi]

I'll assume you're coming in extra shallow. A big thing with space planes now is you have to ride outer atmosphere with your nose as high as possible, 30-45 degrees on if you can hold it. You can also add one of the small radiator panels to bleed some heat away from problem areas. I was having a devil of a time and now I seem to make it without even seeing heat bars.

[Graveworks]

I started a new career in 1.0.5 just to check things out (without messing up my 1.0.4 work) - The new heating and drag models are a nightmare to deal with. I had a contract to get a flight above 70km - at first I would overheat the parachute on the way up, so had to adjust the limits on my SRB, then I had problems slowing down enough to deploy parachutes. Finally managed to make it from a relatively shallow 85km Ap, firing my chutes once I got to 270 m/s and they opened up just 30m above the water. If this is how things are gonna be, they need to move drag chutes a lot earlier in the tech tree.

[juanml82]

I'm not yet trying with spaceplanes, but with vertical rockets the problem I'm having in my 1.0.5 career is this:

I enter retrograde, using SAS, with a heatshield first. That holds. By 25,000 meters or so, the ship (typically, an Mk1 command pod with something like a cabin attached beneath) will tip over prograde and, if I didn't manage to bleed enough speed, the command pod will overheat and explode.

Sounds like another emergency patch like 1.0.2 will be coming to balance these stuff...

[Guest]

I'll assume you're coming in extra shallow. A big thing with space planes now is you have to ride outer atmosphere with your nose as high as possible, 30-45 degrees on if you can hold it. You can also add one of the small radiator panels to bleed some heat away from problem areas. I was having a devil of a time and now I seem to make it without even seeing heat bars.

Cool! I don't know why it works, but it does. I had it in my mind that with an angle of attack that high, I would surely loose control and end up in a death spiral. But, like you said, I barely even got a heat bar, and with no radiators. And no death spiral, in fact, it was quite easy. Now, onto the next adventure. Man, thanks alot.