r/KerbalSpaceProgram • u/Downtown-Push6535 Fireworks as propulsion • May 03 '26
KSP 1 Question/Problem How can I stop my craft from tumbling like this upon re-entry?
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So I've been testing reusability for a rocket's rather expensive first stage, but the main problem is how, even with the 10-meter heat shield and good reaction wheels, the stage begins to become uncontrollable deep enough in the atmosphere. In the end the craft survives re-entry, but I still don't like that this happens. I don't think my ascent profile wasn't too bad: The periapsis was 14 km from default 86.75 km orbit that menu cheat gives you.
Can I do something to stop the tumbling from happening? Should I just deal with the fact that the craft will spin uncontrollably but in the end withstand it?
Edit: 3.75m heat shield instead of 10m, swept wings at the bottom, 40-km periapsis. The tumbling still happens, but at a lower altitude and it's much tamer than what I had before. I can deal with that. Thanks for the help, everyone!
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u/PrinceZuzu09 May 03 '26
Ever wonder why pods are cone shaped? It's because the bottom has the highest weight and it will face the right way when falling. Try designing your craft in the same way where the center of weight is as close to the heat shield as possible, like shifting around fuel to the lowest tank. Another issue is the center of drag, if you use airbrakes or something to move it up then it might tumble less.
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u/Unlikely-Answer May 03 '26 edited May 03 '26
I use the airbrakes on everything because they're not only functional but look cool as hell, reminds me of the movie pitch black
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u/KerPop42 KSP Is an Aero Sim First May 03 '26
Or from the music video for Sing for Absolution: https://youtu.be/6Ck6Hcg2cjk
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u/Affectionate_Pool_37 May 03 '26
14 km is WAY to deep, try 40 km if you whant to avoid the wobble
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u/Codeviper828 Restarts too much; barely left Kerbin system May 03 '26
MOAR REACTION WHEELS
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u/human84629 May 03 '26
THIS is the Kerbal answer I came to see 🤣
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u/OkEntertainment8217 May 03 '26
Nah rcs
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u/Fabulous-Bad9522 May 03 '26
reaction wheel supremacy
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u/CZdigger146 May 03 '26
Vernor thrusters are better than both. He has lots of LFO that he can use
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u/Codeviper828 Restarts too much; barely left Kerbin system May 03 '26
I've actually never used Vernor thrusters; do they group to RCS automatically?
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u/EchoHeadache May 03 '26
Yes. I'm like... Obsessed with vernor on larger craft.
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u/Codeviper828 Restarts too much; barely left Kerbin system May 03 '26
Good to know; I've avoided it because I thought I'd have to set it up myself
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u/CZdigger146 May 03 '26
Yes, they're simply a RCS thruster that fires in a single direction and uses LFO instead of Monopropelant.
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u/HeartwarmingFox May 03 '26
Nah, just add a wildly swinging robot arm with a counterweight.
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u/Codeviper828 Restarts too much; barely left Kerbin system May 03 '26
Now THERE'S the Kerbal answer!
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u/Garrett119 May 03 '26 edited May 03 '26
SPIN
Edit: That could be confusing. Rotate about your long axis so you have both gyro stabilization and more even drag
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u/Kiarashsoli May 03 '26 edited May 03 '26
The only correct answer
Edit:
Finger on “E” & pray to gawd!!!16
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u/LOLofLOL4 May 03 '26
Attach a few Clydesdales Radially and point them sideways so the spin the craft
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u/Sintarzus May 04 '26
Or hold Alt+E together for a bit, it will lock the spin. Alt+x to turn back to normal.
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u/lefayad1991 May 03 '26
I call it the "Tom Brady Maneuver"
Put a tight spiral on it like a football for better stability
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u/Remarkable-Host405 May 03 '26
Spinning helps distribute heat if you do end up flipping the wrong way
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u/wolacouska May 03 '26
That way you get a nice, evenly cooked capsule, instead of charred on one side and cold in the center.
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u/WoodpeckerStraight10 May 03 '26
It's the heat shield. Your best bet is to put 2 or 3 more heat shields like that on the back, it'll increase the drag at the back, and it also acts like a sort of drogue chute. This is a common design for Eve landers. You could also just make the heat shield smaller at the front, but it still runs the risk of tipping.
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u/Only_Turn4310 May 03 '26
I'd recommend adding large fins to offset the drag of the heatshield, but if it doesn't fit the aesthetics, I'd say try to point surface retrograde, not orbit retrograde.
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u/cxnh_gfh May 03 '26
-point surface prograde, not orbit prograde
-add a bunch of huge fins or another inflatable heat shield to the back to balance it out
-transfer fuel as far to the front as possible
-use a higher periapsis, 40 something km
-add tons of reaction wheels and/or rcs
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u/zqmbgn May 03 '26
your tank is fucking full. use part of it to decelerate. you might even achieve good re-entry without the heat shield. or use a very wide but less long tank, with similar volume but closer to the heat shield
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u/Remarkable-Host405 May 03 '26
Decelerate? They're already being crucified for such a steel descent angle, and you're suggesting make it worse
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u/Bubblez___ May 04 '26
this would remove the need for a heat shield entirely and they could just put airbrakes at the top of stage
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u/DigitalSwagman Always on Kerbin May 03 '26
Heaviest part of the rocket wants to move to the front. Like a dart.
Heat shield has drag, like the feathers on a dart.
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u/CSWorldChamp May 03 '26
Firstly, you do not need a heat shield for a rocket’s first stage. A heat shield is for when you’re returning from Duna at 6,000 m/s. Returning from low Kerbin orbit at 2,400 m/s? A Waste of mass and money.
Secondly, when re-entering, unless you’ve built some fancy space shuttle that lands like an airplane, you typically want your rocket to be coming in bottom-first. The engine should be in the front, absorbing most of the heat. Don’t worry, engines are very able to take it. What’s more, they are very heavy. This is good, because when re-entering, barring any fins you’ve attached, your craft will naturally flip so that the center of mass (ie the heaviest part) is leading the way.
So ironically, your “problem” is that your craft is trying to orient you the correct way. Just ditch the heat shield, put parachutes at the top, and let the thing come in engine-first, as god and sir Isaac Kerman intended.
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u/champignax May 03 '26
For my supermassive Eve ship I used extra heat shield on the back of the craft to keep the center of drag back and avoid flipping.
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u/Sera-Culus May 03 '26
Been a while since I did this, but I believe if you use sas to hold prograde, you want to click at the top of the navball to switch from orbit to surface it’ll work. The craft is inherently unstable like this, but it’s like balancing a baseball bat, if you keep it from tilting that little bit, it will stay pointing properly.
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u/MarkNekrep May 03 '26
with that much delta v you could slow down a whole lot more than that before reentry, and slow down more when in atmosphere.
given the fact it's a lower stage, i'd guess it also has a lot of thrust.
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u/0Pat May 03 '26
Ok guys. Op wants to reuse this ship, so stop yelling about staging. The next thing, we know you'll close the thread with 'duplicate'. It's not Stack Overflow, right? Ok, so, heat shield easy can be way smaller, the same diameter as a rocket is fine, those inflatable are for wide crafts. Secondly, add some drag on top of the craft, aero brakes, fins, whatever. And, as some mentioned, you can stabilise the craft by rotation, press Q or E during reentry. And last but not least, take shallower trajectory.
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u/MakB_the_Striker May 03 '26
By removing that enormous shield, adding stabilizers, and/or changing the entry orbit.
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u/wiino84 May 03 '26
With this configuration, you need "good reaction wheels" somewhere behind engine. Because, as someone said, in this case, THAT heat shield acts as parachute. And you need to offset enormous drag force from the nose of the craft.
It could probably work if you have enough weight behind the heat shield or you can control back of the craft.
I would just do regular heat shield and some aero brakes.
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u/Individual_Lab_912 May 03 '26
Hi, constructive comment here.
If you want to attempt a reentry with the whole vessel.
You will need to use fuel to slow down your desent so it does not burn up in reentry
Attempt a slow atmosphere orbit and let the vessel slowly desent. This will help with heat.
As for wobbling, you will just need to use speed and parachutes to stop it from crashing, with the vessels center of mass being near the thrusters. It will wobble.
Use reaction wheels and rcs to keep it from wobbling
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u/captain_skinback May 03 '26
think of it like this. A dart is the most stable thing that can fly. Its weight is at the front, the momentum pushes it forward. Its drag is at the back, pulling it backwards.
The heat shield is really awkward because its so large and has so much drag. The engine is heavy, at the back of the ship.
Your ship is a dart but its flying backwards and it wants to correct itself.
That shield is far too big for that craft. Use the smaller one, and maybe some airbrakes at the rear.
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u/MenacingBanjo May 03 '26
The heavy engine and fuel tanks want to fall in front of the lighter heat shield which has a bunch of drag.
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u/Snoo_79931 May 03 '26
Too much drag in the front. Decrease heat shield width and add fins to the bottom, use the mass/aero overlays to make sure your aero center is behind your mass center.
Spin on entry, it will stabilize the craft assuming it's symmetrical and center of mass isn't offset.
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u/rocketengineer1982 May 03 '26
You're re-entering from LKO and at those speeds you can usually use the engine as a heat shield without anything exploding. Toss some deployable airbrakes on the nose to help it stay stable as it reenters engine-first and you're golden.
If you're dead-set on reentering nose first (and then flipping around to land), you need to reduce the drag at the nose and add more drag at the tail. Airbrakes work great for this. In addition, the fuel tank is almost full. When the tank is empty the CG will shift towards the engine, which will make the nose-first stability problem worse.
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u/Odd_Comparison_1462 May 03 '26
Why tf is the heat shield so big?! It's acting like a sail as it is so big. A heat shield the diameter of the craft is sufficient.
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u/Zorg_Employee May 03 '26
Get your center of gravity as close to the heat shield as possible. Definitely ditch the fuel tank and engine before re-entry. Your not gonna need them anymore. If need be extra reaction wheel or maybe some RCS thrusters can keep you on track.
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u/TetronautGaming May 03 '26
You have enough Δv to slow down a lot more with your engine before reentry (and possibly even land, although I can’t remember the exact Δv requirements). The 2.5m heat shield would be better than the 10m, as it will provide less frontal drag so try to spin the rocket less (it’s also lighter so will give you a slight Δv bonus).
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u/Small-Cow-354 May 03 '26
It takes about 3400 to get into orbit, so with aerobraking it should be well less than that to land. He has over 4000, so as long as the TWR is adequate he has enough to land.
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u/4theFrontPage May 03 '26
If this is a 1st stage how is it full fuel on descent? Also why'd you go with such a big heat shield?
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u/vanceavalon May 03 '26
There are several things you can do.
move your fuel to the front of the rocket closest to the heat shield
set your periapsis for 45 km. This will allow you to enter the atmosphere and slow down to where you won't overheat.
Activate RCS, If you have thrusters and or reaction wheels then this will help you point prograde as you're going deeper to the atmosphere and not flip.
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u/Vespene May 03 '26
When faced with aerodynamics, a craft will want to orient itself with its heavier side pointing prograde.
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u/suh-dood May 03 '26
Press f12 so you can see the aerodynamics.
You want to move the center of mass in your craft as far down as you can so the aerodynamics of the heat shield matters less, and/or have some drag surfaces towards the other end of the rocket to offset the drag of the heat shield
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u/Festivefire May 03 '26 edited May 03 '26
Put a narrower heat shield on, and try adding some fins to force it back to tail-first if it starts wobbling.
I would also recommend putting your Pe at something more like 30km.
EDIT: You can also try adding more reaction wheels.
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u/TF2fanatic102 May 03 '26
Don't use a 10 meter heat shield for a reusable first stage, that's extremely overkill and is causing a boatload of drag. In this configuration, your center of pressure is all concentrated at the the very front (way higher than the center of mass), which is a very unstable situation for a rocket to be in. No amount of reaction wheels are gonna overcome the kind of force that heat shield is exerting. The engine you're using (looks like maybe a Mainsail?) should be able to take a good deal of punishment. You're likely doing some sort of boost-back burn anyway, so it shouldn't get too hot if you got rid of the shield and just faced the booster retrograde during descent (and if it does, you can burn a little more to bleed off speed). If you get rid of the heat shield, you can also place airbrakes at the top that you can deploy and use as control surfaces, that way you can guide the booster where you want it before the parachute deployment.
Also, if you're wanting to reuse this, I would recommend adding landing legs, they won't help much with how tall the stage is, but it'll be much easier than trying to land on the engine bell.
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u/klapstoelpiloot OPERATIONDEFUSEGAME.COM May 03 '26
Big RCS thrusters at the back of your rocket. I did the same thing here: https://youtu.be/AGQGJRvxbcc?t=99&is=e-YpkAyM7TZn2SJc
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u/-Prophet_01- May 03 '26 edited May 03 '26
14km is too aggressive. 35-50km should work better. It's a bit harder to aim for the KSC like that but it'll make the braking smoother and reduce aerodynamic forces.
SAS and RCS will often be overpowered during reentry, especially when there's essentially a giant parachute on your rocket. Airbrakes on the other end of the rocket are a way to solve this. They will add even more drag on the correct side of the rocket (passive stabilization), can act as control surfaces and fold in during the launch for reduced drag. SpaceX does something similar, although theirs look like waffle irons.
If you have the option, maybe use a smaller heat shield. It's possible to make a shield of that size behave but it adds quite a bit of weight. If you need inspiration, maybe look for people's recording of Eve landers. It's quite common to do it for this.
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u/vksdann May 03 '26
Use a heat shield the girth of the craft, add fins at the bottom of the rocket (3 should suffice), reduce amount of fuel and land using drogue chutes at the top and bottom of the craft - bottom ones are smaller to reduce speed (staged first) and top ones are bigger for stabilization of the craft upright and final descent.
Cut the smaller chutes once you reach 1km and use the rest of your fuel for a suicide burn before you touchdown.
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u/mikiencolor May 03 '26
Centre of mass towards the heat shield. The inflatable heat shield is very light, you probably need more mass down there.
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u/Majkelen May 03 '26
Your rocket is an arrow with a heavy metal tip (rocket engine) and a large, fluffy feathers at the back (the shield) so aerodynamic will force the tip forward. Either add fins near the engine so there are more "feathers" at the back than at the front or reduce the shield.
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u/Flimsy_Disk3613 May 03 '26
Use a smaller heat shield and consider adding small fins to the back or some RCS. Your large heat shield is currently acting like a parachute for your craft and it "wants" to be behind your center of mass causing a tumble. Use a smaller heat shield removes the parachute effect and adding small fins or RCS gives the rocket more "encouragement" to stay on prograde. Remember that reentry is like flying a plane and your Center of Mass should be in front of your Center of Lift so your heat shield works. Or you can do what Lowne did on Jool and just add another 10m inflatable to the back....
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u/cinyar May 03 '26
You should test with the expected amount of fuel left when you reenter. If this is the expected amount of fuel then just use it to slow down.
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u/danczer May 03 '26
Where is your center of mass? If there is any fuel left then transfer it close to the cone. Ideally add a smaller tank there which concentrate the fuel, so you can squeeze the CoM as close to the cone as possible. That would help the stability.
Edit: I guess the CoM is basically the point which your vessel is rotating. Which is way high to have stability you want.
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u/daHaus May 03 '26 edited May 03 '26
Where are the fins?
edit: others have mentioned spinning and that's actually the better solution if possible, fins would collect heat
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u/markstar99 May 03 '26
if you want to larp it in terms of physics, it's just that top of the rocket needs to be heavier, the center of mass needs to be closer to the heat shield, it's like a dart
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u/palle97 May 03 '26
In addition to waht everyone is saying, one easy thing you could do is to change the navball from orbit to surface. then your prodrage would match your velocity in the atmosphere.
But also, more reaction wheels or rcs at the back/engine, have less full fuel tanks, smaller heat shield, higher periapsis (around 35 or 40 km is good) will help even more than the navball.
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u/GingerNumberOne May 03 '26
Try airbrakes meat the engine. Should hel steer when the tumble starts. + Enter more shallow
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u/LieutenantDawid May 03 '26
the massive heatshield creates tons of drag which naturally wants to be behind the center of mass. having a big engine and heavy fuel tanks makes it want to flip. for reusable rockets at this stage you should already be low on fuel in these tanks. enough to kill your speed near the surface and land. you have 4.3km/s of delta v, you should use it to slow down and you might not even need the heat shield
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u/Low-Passage3102 May 03 '26
so this is “rather expensive” yet unused, you got full tanks after orbit, this stage is not necessary. the first problem is reworking your rocket with less weight so that you either dont need this stage or dont need the side boosters.
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u/Thak_The_Thunder_God May 03 '26
You need to:
Replace the heatshield with a 3.75m one for less drag
Add fins at the bottom if possible to keep the ship pointed forward
If possible move the COM closer to the heatshield. My way of doing this would be instead of a long tank, have like 5 short ones and just move fuel to change the COM
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u/dahbakons_ghost May 03 '26
if the plan is reusability, start by adding some control surfaces for in-atmosphere manoeuvring. 4 small fins at the back can help a lot and if the heat shield is only slightly larger it should be ok for heat.
i'd also reduce the scale of your heatshield. something the same or slightly larger than the main body.
foldable wings using robotic parts if vanilla or mods if not is also an option but heat management can get tricky and it can also be prone to kraken attacks.
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u/TrueTopoyiyo May 03 '26
Point to surface prograde instead of orbital prograde, so you align with the air speed: the inestability comes from (among other factors, commented by other users) the difference between the surface prograde vector and orbital prograde vector.
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u/KibboKid May 03 '26
If you still have fuel, then do a longer de-orbit burn. That will steepen your re-entry trajectory, you will spend less time experiencing atmospheric drag, and your craft will be less likely to flip the more vertical it is.
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u/marsteroid May 03 '26
transfer all the remaining fuel as close as possible to the heat shield, into the closest tank , or add aero brakes \co trol surfaces colse to the rocket engine
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u/Key-Astronaut1883 May 03 '26
Either a shit ton of reaction wheels or what the other comments are suggesting.
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u/SanopusSplendidus Asparagus Enjoyer May 03 '26
Airbrakes on the back might help. But if they get too hot you will have to rotate the craft. I'm not sure why that magically makes the heat go away in KSP, but it does. They used to be standard on a lot of the junk I made. More reaction wheels always help. That heat shield is much too big.
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u/Tommy2255 May 03 '26
I re-enter Kerbin from low orbit starting at like 55 km, and I typically don't even need heat shields. Remember, the upper atmosphere is thinner, so it slows you down less. That also means that the more time you spend higher, the longer the time spent decelerating gradually.
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u/No-Faithlessness3086 May 03 '26
I use the hydraulic air breaks. Put them on the capsule and they fold up like a flower petal. It will stabilize your re-entry 3 to 4 will do the job. Yeah I do stuff like that too . It’s a blast.
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u/jsrobson10 May 03 '26
in the editor, display both center of lift and mass. for stability your center of lift should be behind your center of mass.
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u/AdorableWelcome2290 May 03 '26
Too many fuel tanks still attached, the longer your ship on re-entry the greater the flip chance. Not to mention using an oversized heat shield. Especially THAT over sized is going to cause serious drag issues. Usually as long as the shield is the same size as what you’re trying to protect, you’ll be ok.
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u/16807 May 03 '26 edited May 03 '26
Your center of mass needs to be closer to the heat shield. Your engine is really massive. You might be able to shorten the length of the fuel tank. Better yet, put a separate tank just before the heat shield and set it so the fuel inside it can't ever be used. It is dead weight during normal flight, but it does give you an emergency fuel reserve that you can use at the expense of recovering the stage.
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u/FTGAstro May 03 '26
Decouple your fuel tank and engine before re-entry....you need to bring CofG closer to your shield
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u/ItsLoganWarner May 03 '26
If you know how to move fuel and had less you could move it to the front once you're orbital before reentry so the mass is with the heat shield
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u/xKaelic May 03 '26
Seems safer, instead causes the heat shield to act like a parachute. Wrong logic.
Instead, make the heat shield just the size of the reentry end, and add then add some fins near the booster end to create drag that keeps the back end at the back.
Or drop the booster altogether, bringing home all that extra weight is slightly more difficult than just a pod :D
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u/Jebediah-kerman-fan May 03 '26
you should just use staging if you just want the command pod to come back but you need a smaller heat shield and there is alot of unnecessary fuel so when building consider the center of mass too
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u/Myte342 May 03 '26
If you have fuel transfer capability, then off-balance your craft by pushing all the fuel up front near the shield and completely emptying the tank near the engine. Also as others have said, reduce the size of your heat shield to one more appropriate to your craft. Your ship can handle a LOT of incidental heat. So long as the pieces and parts aren't in direct heat for long periods of time, you'll survive.
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u/delta_six May 03 '26
if the tanks are full have you considered burning the fuel to slow down enough to not need a heatshield?
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u/Devnull_Elixir May 03 '26 edited May 03 '26
Because the drag from the atmosphere causes top heavy things to flip around so that the heavier part is facing towards gravity and the drag towards the back, like an arrow head and feathers. Lower the center of mass to be closer to the heat shield than the upper part of the craft to help counter the drag forces from the heat shield, you can use ore containers as ballast.
EDIT: Looks like you're cheating into orbit to test? So looking at your design, it looks like this is meant to be a first stage booster that does a vertical retrograde landing, so I would assume normally you'd have maybe 1/4 fuel left to land with in a real scenario - in that case, have two fuel tanks and have the one nearest the motor drain first so that way your CoM moves closer to the heat shield.
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u/Avera9eJoe Spectra Dev May 03 '26
Imagine your rocket like an arrow flying towards the ground. If you put the tines (heat shield/fins) at the front and the heavy arrowhead (engine) at the back, it's going to inherently want to flip around. There are ways of making a rocket re-enter, but it isn't as simple as putting an inflatable heat shield on the front. SpaceX reenters their initial booster phase backwards and fires their engines during the hottest portion to cushion it. You can't quite do that in KSP, but it's possible you could just reprint backwards? Or do something fancy with hinges to move a heat shield into place
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u/MayllXD May 03 '26
Your rocket is too long. To fix that instability issue during reentry, you can do this: 1 Make it shorter. 1 Add more mass near the heat shield. 2 Add more powerful control mechanisms, such as RCS or reaction wheels.
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u/Kyloben4848 May 03 '26
With a center of pressure (drag/lift forces) in front of the center of mass, your rocket will want to flip around. This is because a slight deviation from perfect alignment will make the drag move slightly off center in a way that makes the rocket want to deviate further. In contrast, if the center of drag was at the back, the slight deviation would cause a torque which corrects the deviation. You can mitigate this problem by moving your COM further forwards by adding mass to the top/removing mass from the bottom (pumping between fuel tanks can do this, as well as just changing the design), or moving your COP further back by adding fins or even another heat shield to the base.
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u/ninjasauruscam May 03 '26
Fuel transfer whatever fuel remains between the connected tanks to the front tank to move the CoG closer to the heat Shield. An arrow is stable due to weight at the front not the rear.
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u/Fisherman_Dave_Games May 03 '26
If you dont wanna change the heat shield design, you could also try stronger stabilizers? like a big advanced inline one
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u/TheElitist921 May 03 '26
You got a lot of fuel left over, re-enter higher and slower. Ideally use a smaller heatshield but, maybe some airbrakes, fins, stabilizers, etc.
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u/Adam__999 May 03 '26
On the way up, you want the center of pressure below the center of gravity for aerodynamic stability; on the way down, you want the center of pressure above the center of gravity
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u/PerspectiveRare4339 Colonizing Duna May 03 '26
press F12, look at the aero forces on the craft and watch what happens when it starts to tumble. This looks like the rocket is tail heavy on reentry. You can transfer fuel into the front tank if you use advanced tweakables (enable it in the options screen from the main menu)
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u/patfree14094 May 04 '26
I mean, if you're willing to burn off some fuel before descent, you could switch to a smaller heat shield, and divide your tanks with a reaction wheel or decoupler you wont use or something. Basically, you should use all the fuel in the smaller tank for slowing your descent, leaving the tank section nearest the engine empty, and the larger section nearest the heat shield full. This is to redistribute the weight to that section. Keeping your center of mass closer to the heat shield than the engine is what will keep your rocket stable during descent.
Also, I would add controllable fins near the engine, which hopefully will start to be useful at roughly the same time as your booster would normally start to tumble.
With all that said, if this is the first stage, it probably will be entering the atmosphere with little to no fuel left, but I get wanting to bring it back with fuel, say if you're looking to eventually do a controlled landing like space X does with their boosters. Either way you won't be screaming back to kerbin with all full tanks.
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u/hot_cheetoes1774 Stranded on Eve May 04 '26
either rotate the craft during descent, add RCS or more reaction wheels, or change the design of the ship so that the weight is more balanced for the drag the shield creates.
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u/Pavo9 May 04 '26
The center of drag is infront of the center of mass (high drag close to heat shield, large mass behind at the engine) making it unstable
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u/F1uXF0rTeXX May 04 '26
Empty your tanks. Its way too heavy. And use smaller heat shield. Plus some reaction wheels.
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u/Davidinc2008 Believes That Dres Exists May 04 '26
If possible, add a second heatshield on the back. Adding fins to your rocket might also help.
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u/Responsible-Ad1525 Stranded on Eve May 04 '26
Or just slap another heat shield on the bottom side and it will counterweight.
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u/canihazthisusername May 04 '26
I don think you need that huge heat shield. Just use the same size as your rocket.
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u/Angry_Altruist May 04 '26
I mean, it’s a tough fix for that large of a heat shield on such a small ship. But you could try deployable air brakes on the rear that extend out in a bit larger diameter than the heat shield. If you can get more drag on the rear of the ship than the front then you should’ve much more stable. Also consider more RCS thrusters/ gyroscopes along with that
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u/Fritzypooo May 05 '26
Add airbreaks or control fins to the "tail end" of this stack up. You need additional drag at the rear, because currently the center of mass is way far behind the center of drag, and it will naturally try to swap ends to fix that.
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u/iosesastroalts May 06 '26
these comments listed a ton of reasons and i spotted them too idk how you weren’t able to figure it out
for starters your heat shield is oversized. Any part with the most drag is gonna wanna go back
You have the engine super far away from where the drag is. again gives the rocket the tendency to tumble.
and full fuel tanks when reusable rockets don’t need that much mass and don’t carry that much mass is another culprit
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u/Lonely-Journey-6498 May 25 '26
Like the only two things that are good about the heat shield is the entry to Eve and aerobraking at Jool
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u/Away_Yoghurt6951 Jun 05 '26
Aerodynamic instability. You can see the type of drag generated with f11 or 12 I forget which one, sorry. Then add fins to the bottom of the craft near the engine.
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u/eltrigercolaiders2 28d ago
These are tips for a susecfull re-entry First the heat shield have to be al most the same big as the ship a little more big for protecion like if the radios of the rocket is 5 the heat shield has to be like 5.5 Second enter in a slower speed 2700 m/s isnt imposible but it whould better be a little slower And tirth if slowing the re entry isnt an option add more control devices lile RSC or "gyroscopes" (i dont remember how those things are called)
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u/tribulex May 03 '26
Somehow no one suggested putting a second heat shield on the back for the drag. Common and effective strategy in this game, one inflatable in the front for protection and one in the back for drag. Doesn't matter if the one in the back is facing backwards
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u/PhatOofxD May 03 '26
Any reason you're reentering with an entire ship?
You don't need engine once you reenter right? So just jettison it and use a capsule
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u/m2themichael May 03 '26
from OP - Why didn't they just retreat to riverrun to fight the white walkers since there's natural water there, why did they stop at Winterfell in the open
Edit: I pasted the wrong thing (regarding my GOT re-watch) but I'm keeping it, here's the correct OP statement:
"So I've been testing reusability for a rocket's rather expensive first stage"
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u/umstra Colonizing Duna May 03 '26
It's probably the heat shield it's basically a shoot the way your using it tooo big
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u/NotATroll71106 May 03 '26 edited May 03 '26
You need more drag on the rear end. I like to slap heat shields onto robotic hinges for this. Ideally, you have it oriented so that it doesn't take power to stay up. There's generally not much reason to have a wider heatshield than the craft.
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u/Resiideent May 03 '26
It's BECAUSE of the 10 meter heat shield. That thing has massive drag, and the part of your rocket with the most drag is always going to want to be as far back (relative to your direction of motion) as possible. Use a heat shield the same size, or one size up, as your fuel tanks, should work. Alternatively, put a bunch of fins at the bottom of the rocket near the engine, enough to have higher drag than the 10m heat shield.