How to safely enter the atmosphere and land my SSTO SP?

[DCWarHound]

Hi

I'm having trouble during re-entry,my space plane keeps overheating and blowing up (note that my heat settings are set to max).Below are some images of my SSTO SP (my very first ssto,it's still in the design phase).Tell me i need to add anything to it.

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Edited July 24, 2015 by DCWarHound

[Sharpy]

I don't see any airbrakes.

If you don't have airbrakes, safe reentry with SSTO is gonna be hard. Not impossible but requires some very skillful flying.

[ForScience6686]

You can bleed off speed in the upper atmosphere by using "S" turns. Or keep your AoA high so you have your belly increasing your drag. That's what I used on my first suborbital hop in my space plane last night.

[Starwhip]

Obligatory answer: "Carefully".

But in all seriousness, you should opt to use airbrakes, or, in the case you do not have them, aim for a higher periapsis when you reenter, possibly skimming the atmosphere several times. Shoot for about 40,000 meters and see how it goes. Remember, you can always go too high, but not always too low.

Another thing to try is S-curves. The space shuttle did it. Turn to one side, then turn to the other, then back again, until you are slow enough.

[Good_Cat]

AirBrakes wrap 8 or so round that tail and mainsail even if it is for looks, i don't need to use airbrakes unless im landing using the below.

Drop periapsis to 50km roughly above where you want to land, you have MechJeb so this is easy, open Smart.A.S.S - SURF - SURF again heading 90 pitch 30-35 roll 0.

SAS will try to hold a 30-35 pitch up into the atmosphere giving you a nice long steady glide.

RCS can help hold this.

Any lower than 40km peri for a big heavy craft and you smash into the thicker atmo real fast , the above will be a long burn with plenty of aerobraking in the high thinner atmosphere.

I've brought back a Mk3 Spalce Plane with its cargo (5 man Tourist Taxi, which filled the double bays because i forgot solar panels on it and though f*** it.... i wonder if i can).

Edited July 21, 2015 by Good_Cat

[Edax]

Sticking some radiators on the underside of the cockpit couldn't hurt. If your pointed prograde, that's going to be the hottest part of the craft during reentry. You may also want to stick a small heatshield in the front slot on the cockpit to further absorb extra heat.

[Coga19000]

The simplest way you can go about it without modifying your spaceplane is to take advantage of the natural lift. Even at the tenuous air at the upper levels of the atmoshpere, your extreme speeds and your large wing area will give you enough Control to your vertical speed -to the point where you can start ascending again when things get to hot It might get you off track, but you can just cruise to base with your jets after reentry is over.

If this is not enough, I saw airbrakes and S-Turns being suggested above. Properly implemented, these are also excellent solutions.

[Streetwind]

The key with spaceplanes is to slow down fast. You have a limited amount of time before your plane accumulates more heat than it can hold. During that time, you need to stop being so fast that you generate shock heating.

Therefore, avoid the "Mars Atmosphere Dilemma" you get when staying high up: too little air to slow down, but still enough air to fry you.

If you don't have the magic airbrakes available yet:

- Do a steeper reentry, but be careful... you do eventually need to level off to slow down at some point, before going all the way down, or you will be melted.

- Pancake! Flip your biggest, broadest barn door profile into the airstream as long as you can hold it stable. The Space Shuttle did this for most of its reentry.

- After you can no longer pancake, fly S-turns back and forth. This creates drag and costs a lot of speed. The Space Shuttle also did this.

[imaspacestation]

Everyone has already mentioned - use a high AoA when re-entering so that your belly will slow you down. However I just wanted to add that you need to be careful here, because once you start slowing down and getting deeper into the atmosphere, the plane might not be able to sustain the high AoA and you might lose control, so just remember to keep adjusting it as you slow down and descent.

[capi3101]

Everyone has already mentioned - use a high AoA when re-entering so that your belly will slow you down. However I just wanted to add that you need to be careful here, because once you start slowing down and getting deeper into the atmosphere, the plane might not be able to sustain the high AoA and you might lose control, so just remember to keep adjusting it as you slow down and descent.

Which is when you use RCS to hold the craft's AoA at a high angle - which is also something the shuttle did. I employ a combination of the suggested techniques - airbrakes, high AoA and S-turns - on most of my craft during the re-entry process; my Vulture 7 spaceplane usually doesn't even display heating bars during re-entry as a rule, which the OP should take as a measure of the effectiveness of these techniques.

[ajburges]

Enter with a shallow kobra manuver.

I have yet to pass 60% crtical temperature (on radial batteries in a cargo bay) with reentry on a 100x45 orbit and a 30° over the horizon. At 36 km I reduce AoA to 15° to avoid a stall. Above 50 km you can enter perpendicular to travel. Lower Ap and higher Pe make it even safer.

Kobra manuver is the safest way to blessed speed. It gives lift in addition to drag so you stay high longer. S-turns are the shortest distance way to bleed speed. The same drag without the lift. You also follow a longer route.

[Hagen von Tronje]

I did my first successful SSTO and landing last night using a spaceplane.

I didn't use airbrakes. I lowered periapsis to about 10km (which is maybe lower than necessary but I figured I'd try for a steep reentry) then entered the atmosphere belly facing retrograde. Nothing overheated (or showed bars) or took any damage and I braked from about 2500m/s to pretty much whichever speed I felt like gliding at. For this maneuver I kept RCS on, and I had a pair of one-way RCS nozzles on the top and bottom of the nose specifically for forced attitude control in situations like this where I need to defy the atmosphere a bit. Also had 4-way RCS nozzles on the wingtips.

I was able to reignite airbreathing engines by dropping to safe speed then turning towards prograde to get airflow, but only needed this if I wanted precision landing site selection as I did gliding landings, usually touching down at under 40m/s and braking to a full stop well within runway lengths.

Don't know if that's the best way, but spaceplane part descriptions are explicit about their use for reentry shielding so that's exactly how I employed them. Though come to think of it, I had monoprop tanks and fuel lines down under the wings and none of that overheated either. I should also point out that I am an awful pilot but do it all by hand using a keyboard so I don't think the maneuver can be THAT hard to execute, FWIW.

[DCWarHound]

Thanks for the help everyone.

I tried quite a few times and failed most of them,air-brakes helped lots as well as S turning.

[Thorbard]

On 21/07/2015 at 7:41 PM, ajburges said:

Enter with a shallow kobra manuver.

I have yet to pass 60% crtical temperature (on radial batteries in a cargo bay) with reentry on a 100x45 orbit and a 30° over the horizon. At 36 km I reduce AoA to 15° to avoid a stall. Above 50 km you can enter perpendicular to travel. Lower Ap and higher Pe make it even safer.

Kobra manuver is the safest way to blessed speed. It gives lift in addition to drag so you stay high longer. S-turns are the shortest distance way to bleed speed. The same drag without the lift. You also follow a longer route.

I was struggling with reentry of Mk2 "sled" sort of like the ESA IXV or Dream Chaser and this seemed to be the way to go.

 

I did struggle with atmospheric pitch authority though and had to rely on RCS most of the way down.

[AeroGav]

It looks like the OP has FAR installed.    Whilst I have found I can achieve better transonic drag/easier passing through the sound barrier on a well tuned design, I've also had much higher landing speeds with FAR than stock Aero - two or three times higher.   So I am wondering if FAR is reducing the lift you get on re-entry ?

In the stock game,  I took this mark 1 spaceplane from a 75 km orbit and retro burned to 30km periapse.    The mk1 cockpit has poor heat tolerance and the airliner wings are even worse.  It has also only just completed it's ascent half an orbit ago so wasn't fully cooled down.   We came close to parts overheating on re-entry but did not actually blow up.   Also, the minimum altitude reached was about 42 km, despite the 30km periapsis.  After that the lift from the enormous wings started sending us back up again.

To me it's all about the lift, and not coming in too aggressively with a low periapse. (on spaceplanes i prefer to aim higher, like 40km )

I am not convinced on S turns.  If you are generating lift, you want all that lift used to keep you UP and out of the thicker atmosphere where the heating gets worse, for as long as possible, giving you more time to slow down.   If you bank into a hard turn most of that lift is being diverted for going sideways, and you drop down earlier, reaching the thicker air while moving at a higher speed.

Max lift is at 30 degrees AoA but given the difficulty holding an exact angle and the way it falls off quicker if you go over 30 than if you undershoot, you're better off aiming a little below.     If I'm not in immediate danger of blowing up,  I use AoA to try controll my landing point.     If i'm overshooting, i deliberately pitch up as hard as possible to increase drag.       If i think i might be coming up short,  i pitch down to less than degrees above prograde, where lift./drag ratio is better.    You drop initially but then your descent and deleration rate slow down, as you 're at a better "gliding speed".  Again though , this is all relating to stock aero.

https://kerbalx.com/AeroGav/whippynerv

[bewing]

You might want to read this thread, on exactly this subject: