Heat in 1.1

[Firemetal]

This question is un-prepared. Anyway I have problems entering the atmosphere with the mk1 cockpits. It seems that whenever I re-enter the atmosphere with a mk1 cockpit (mk1 SSTO), the cockpit absorbs all the heat. I get a gauge on the cockpit only and it heats up in about 15 seconds. The mk1 command capsule is pretty much the same. I have a simple command capsule with a heatshield and parachute and if I don't turn off SAS and let the atmosphere point me in the exact right direction, the same thing happens.
 

I know I have posted something like this before but it was all rage and I didn't really help by not posting pictures. I will post them if you need them and if you want information on crafts, just ask! I won't be lazy and not give parameters this time!

Thanks!

[bewing]

The MK1 stuff is tricky when it comes to heat. You have to be tricky in return.

For basic reentry, there are two factors that you have to deal with. MK1 parts have low heat tolerance, and MK1 parts have very low drag, so they don't slow down. In fact they often accelerate as they fall, even in dense atmosphere at mach 6. If they are pointing prograde and you do nothing, they will blow. Period. How to prevent it? Put tailfins or wings on them to create lots of atmospheric drag. Put on a heat shield. Put on a radiator. Either come in much steeper, or much more shallowly.

For spaceplanes, it is even a little harder -- because the nose always does want to point prograde. They already have wings, so you have a source of drag if you can just keep the nose perpendicular to prograde. So reaction wheels and a radiator are smart moves.

But if you are at 60km altitude, and you burn retrograde enough to bring your surface speed down to 1500 m/s, then you can reenter anything and it's a cakewalk -- if you make sure to tumble on your way down.

 

[Firemetal]

Ok. Right now I am trying to build a mk1 ssto to Duna. I have two choices. One I can learn how to re-enter with mk1 parts or build a cockpit with a command chair in a service bay. 

Which would you advise?

[bewing]

Heh. Does it need to get all the way to Duna and back to KSC on one tank of gas? Or is refueling permitted?

If you can refuel, then just make sure you have a couple hundred fuel left in LKO and retroburn it at 65km altitude at the end of the Great Desert. Your reentry will be so easy you won't believe it.

If refueling is not allowed, then you should just use a big reaction wheel and reenter like a pancake.

Putting command chairs in service bays is naughty. How can they see, in order to fly?

[Firemetal]

9 hours ago, bewing said:

Heh. Does it need to get all the way to Duna and back to KSC on one tank of gas? Or is refueling permitted?

If you can refuel, then just make sure you have a couple hundred fuel left in LKO and retroburn it at 65km altitude at the end of the Great Desert. Your reentry will be so easy you won't believe it.

If refueling is not allowed, then you should just use a big reaction wheel and reenter like a pancake.

Putting command chairs in service bays is naughty. How can they see, in order to fly?

I usually add a probe core when I have a kerbal in a service bay. Its just flying safe.

[Firemetal]

The MK1 cockpit seems impossible to re-enter with. I have to build an 80 ton mk2-3 SSTO to go to ORBIT and back. I have tried re-entering at 30km and taking a direct descent burning from Desert west of KSC with a trajectory to hit the water just east of the KSC. You know the drill. Anyway I burn up either way so maybe a mod is causing this? Or is the cockpit just a fireplace?

Edit: Wait do air-brakes help?

Edited June 25, 2016 by Firemetal

[bewing]

Well, I never try to use the MK1 cockpit. I always use the MK1 command pod instead. You can put a Small Nosecone on the end of the command pod, and that will go a long way to preventing heatsplosions. A parachute also works, but it's not as good as the nosecone for heat resistance. And anyway, the command pod weighs less than the cockpit, and has a nice actual ladder on the outside for taking data, and costs less, and probably has lower drag ....

When using MK1 components, I always set my reentry Pe at 59km to 63km. Heating goes as velocity cubed, so I think it's very important to scrub off those first 200m/s in the stratosphere before getting down to the dangerous part of the reentry. Other people will disagree, but I don't think they've really tried it.

I hear airbrakes do sort-of work, but they have a very low heat tolerance, and I think that unless you are careful about how you use them -- they will be the things that blow first, and maybe take the rest of your ship out with them.

[Firemetal]

18 minutes ago, bewing said:

Well, I never try to use the MK1 cockpit. I always use the MK1 command pod instead. You can put a Small Nosecone on the end of the command pod, and that will go a long way to preventing heatsplosions. A parachute also works, but it's not as good as the nosecone for heat resistance. And anyway, the command pod weighs less than the cockpit, and has a nice actual ladder on the outside for taking data, and costs less, and probably has lower drag ....

When using MK1 components, I always set my reentry Pe at 59km to 63km. Heating goes as velocity cubed, so I think it's very important to scrub off those first 200m/s in the stratosphere before getting down to the dangerous part of the reentry. Other people will disagree, but I don't think they've really tried it.

I hear airbrakes do sort-of work, but they have a very low heat tolerance, and I think that unless you are careful about how you use them -- they will be the things that blow first, and maybe take the rest of your ship out with them.

Yeah but I have trouble reentering with that too. I will try it but the mk1 cockpit looks way better!  

Thanks! 

[bewing]

2 minutes ago, Firemetal said:

 I will try it but the mk1 cockpit looks way better!  

Agreed.  But I can assure you that you won't get to Duna and back in an SSTO that is pretty.

[Firemetal]

13 minutes ago, bewing said:

Agreed.  But I can assure you that you won't get to Duna and back in an SSTO that is pretty.

Matt Lowne did. But I'll never be as good as him. He is the God of SSTOs! 

Edit: The word "never" is negative. Maybe someday I will.

Edited June 26, 2016 by Firemetal

[Firemetal]

Uhhh

The mk1 command pod was the same.  I was able to maintain a high-ish AoA and survive barely thanks to the slightly higher max thermal attributes. But the critical thermal percentage peaked at 94% which isn't great. Sooooooooo... I'm going to have to use mk2-3 sstos and use an 80 ton plane to get to Duna and back. Great!

[FullMetalMachinist]

48 minutes ago, Firemetal said:

But the critical thermal percentage peaked at 94% which isn't great. Sooooooooo...

Sooo... What's the problem? 

It was pointed out in your other thread asking about reentry heat that this is pretty much normal. 

Seeing the "overheat" bars isn't bad. Even having those bars get really close to max isn't bad. The only bad thing is if something goes 'boom'. 

[Firemetal]

Just now, FullMetalMachinist said:

Sooo... What's the problem? 

It was pointed out in your other thread asking about reentry heat that this is pretty much normal. 

Seeing the "overheat" bars isn't bad. Even having those bars get really close to max isn't bad. The only bad thing is if something goes 'boom'. 

The problem is that things are going to go boom if I'm coming from Duna at 3300 m/s. That was re-entering at 2200 m/s from an 80km ap.

[bewing]

1 hour ago, Firemetal said:

Uhhh

The mk1 command pod was the same.  I was able to maintain a high-ish AoA and survive barely thanks to the slightly higher max thermal attributes. But the critical thermal percentage peaked at 94% which isn't great. Sooooooooo... I'm going to have to use mk2-3 sstos and use an 80 ton plane to get to Duna and back. Great!

I think you're not doing something quite right, then. I have no trouble at all reentering my MK1 SSTOs. And the aerobraking from 3300 to 3100, from 3100 to 2300, and reentry, are three completely separate steps -- so no, there is no "boom" problem there, just so long as you can reenter.

[Firemetal]

46 minutes ago, bewing said:

I think you're not doing something quite right, then. I have no trouble at all reentering my MK1 SSTOs. And the aerobraking from 3300 to 3100, from 3100 to 2300, and reentry, are three completely separate steps -- so no, there is no "boom" problem there, just so long as you can reenter.

I have tried 50km periapsis, 30km pe, 10km pe and direct descent. None of them worked except the 10km when I used the command pod. Maybe I have a mod that is bugging my game? 

Edit: Deleted AB launchers and mechjeb. These are parts and extra interface mods so they are probably not it but at this point, I don't really care.

Edited June 26, 2016 by Firemetal

[bewing]

Try 64km -- if that doesn't work better, then maybe post a craft file?

[Firemetal]

11 minutes ago, bewing said:

Try 64km -- if that doesn't work better, then maybe post a craft file?

Ok will do that but I doubt it will work. And a craft file is a great idea.

[Firemetal]

https://kerbalx.com/Firemetal/Private-Duna-SSTO

I made it past re-entry but at that high altitude, you're circumnavigating the planet inside the atmosphere! .-. Tough to predict landing site. Anyway try this.

Sorry for no thumbnail!

Edited June 26, 2016 by Firemetal

[bewing]

6 hours ago, Firemetal said:

https://kerbalx.com/Firemetal/Private-Duna-SSTO

I made it past re-entry but at that high altitude, you're circumnavigating the planet inside the atmosphere! .-. Tough to predict landing site. Anyway try this.

Sorry for no thumbnail!

Actually, it's not that hard to predict. You scrub speed until you get the Ap down to about 66km, then you click "prograde". You circumnavigate inside the atmosphere until you are over the beginning of the Great Desert. Then you take the nose up to 90 degrees. Then it's just a matter of speed control (by varying your AoA, or tumbling your ship) to glide down to the runway. Takes a little practice to know what speed you want when you are over which landmark.

I'll try your ship out in a bit.

[bewing]

I just tried launching it from the runway as best I could, and I blew it up at about 21km altitude, at 1400 m/s. I'd be adding a bit more wing, and changing the rapiers for whiplashes.

Edited June 27, 2016 by bewing

[Firemetal]

Huh? I got it into orbit just fine.

[bewing]

Ah -- I didn't realize you have some oxidizer hidden somewhere on that thing.

(And you should take the monoprop out of the nose. )

But OK, I can get it to orbit with over 1500 fuel left.

-- Your plane has amazingly good pitch stability on reentry, for having such a pitiful amount of reaction wheel. And when empty, it flies OK at 70 m/s for the landing. I modded it to have one less battery, and added a small reaction wheel for kicks. But yeah, on a shallow reentry I had no trouble at all bringing it in. It does not slow as fast as my spaceplanes, so I think starting the pancake mode aerobraking around the meteor crater at 62km to 63km would bring you down right around KSC.

-- Hmmm. You may need to start pancake mode several hundred km before that.  But your plane also ditches in the water pretty good!

Edited June 27, 2016 by bewing

[Firemetal]

10 hours ago, bewing said:

Ah -- I didn't realize you have some oxidizer hidden somewhere on that thing.

(And you should take the monoprop out of the nose. )

But OK, I can get it to orbit with over 1500 fuel left.

-- Your plane has amazingly good pitch stability on reentry, for having such a pitiful amount of reaction wheel. And when empty, it flies OK at 70 m/s for the landing. I modded it to have one less battery, and added a small reaction wheel for kicks. But yeah, on a shallow reentry I had no trouble at all bringing it in. It does not slow as fast as my spaceplanes, so I think starting the pancake mode aerobraking around the meteor crater at 62km to 63km would bring you down right around KSC.

-- Hmmm. You may need to start pancake mode several hundred km before that.  But your plane also ditches in the water pretty good!

Pancake? You mean pitching up 90 degrees?

Also I clipped oxidizer into the side fuel tanks. Yeah its kind of cheating.  

Edited June 27, 2016 by Firemetal

[bewing]

13 minutes ago, Firemetal said:

Pancake? You mean pitching up 90 degrees?

Yup.

13 minutes ago, Firemetal said:

Also I clipped oxidizer into the side fuel tanks. Yeah its kind of cheating.  

Yeah, it is a bit.