Pawelk198604

Spinning spacecraft during re-entry to slowdown

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I noticed that when i spin my spacecraft (while putting heatshilt still forwar into atmosphere) during re-entry my spacecraft slow down more quickly, it's very important since new realistic aerodynamic was implemented after game was released, in early access re entry was more easier, but i like the new aerodynamic because i like KSP "not because it is easy but because it is hard" ;-)

I wonder does spining spacecraft was used in real life spacecraft.

Edited by Pawelk198604

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IRL spinning is usually very bad. Leaving aside structural loading, dynamic loading, and aerodynamic loading, it creates a lot of ... interesting equations when it comes to the controller math as well. 

Keeping things not spinning just makes things simpler.

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4 minutes ago, steuben said:

IRL spinning is usually very bad. Leaving aside structural loading, dynamic loading, and aerodynamic loading, it creates a lot of ... interesting equations when it comes to the controller math as well. 

Keeping things not spinning just makes things simpler.

So how to slowdown spacecraft, fast enough to not split poor Jebediah into atoms, :confused: and not force me to resurrect him trough revert :wink:

even trough other not pilot kerbonauts, like Bob or Bill, especially if it comes to steep suborbital reentry.

 

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Spinning can be very bad (a spinning issue caused Gemini VIII to abort a matter of hours into its mission) but controlled rotation about the roll axis can also be helpful to a spacecraft, especially during atmospheric entry. 

My understanding is that Mercury spacecraft used spin stabilization during the high-g portion of their reentry into the atmosphere (if somebody could explain what impact that had on the descent I'd really appreciate it). Apollo command modules and Soyuz descent modules performed and continue to perform lifting entries while spinning. The vehicles' center of mass is offset from its axis of symmetry, so by rotating the capsule during descent the spacecraft crew is able to have a small amount of control over the landing location of their vehicle. 

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39 minutes ago, Pawelk198604 said:

So how to slowdown spacecraft, fast enough to not split poor Jebediah into atoms, :confused: and not force me to resurrect him trough revert :wink:

even trough other not pilot kerbonauts, like Bob or Bill, especially if it comes to steep suborbital reentry.

 

You need to shed speed quickly. Heatshields are not very helpful for this. Tumbling is helpful. Aerodynamics are helpful. You need a ship that has good aerodynamics on liftoff, and very bad aerodynamics during descent. This is definitely possible to do! Think about it. It really is easy to make an RV that reenters from orbit with no heatshield at all, if you are clever about your aerodynamics.

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Speedbrakes, if you have them.

But what kind of return are you doing?  I just hit 1.1 and a few suborbital returns didn't work out for my crew, because if you have a relatively steep descent, you won't slow down enough - either it will burn up - explode, or you'll get through, but no time to get to the safe zone to deploy chutes before you smack kerra firma.

You want a 10-20 degree entry to maximize re-entry heating / energy bleedoff, and then also think about aerodynamics as the others have stated.

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1 hour ago, steuben said:

IRL spinning is usually very bad. Leaving aside structural loading, dynamic loading, and aerodynamic loading, it creates a lot of ... interesting equations when it comes to the controller math as well. 

Keeping things not spinning just makes things simpler.

I was thinking of the interesting equations that it'd have on the astronauts stomachs...

 

38 minutes ago, bewing said:

You need to shed speed quickly. Heatshields are not very helpful for this. Tumbling is helpful. Aerodynamics are helpful. You need a ship that has good aerodynamics on liftoff, and very bad aerodynamics during descent. This is definitely possible to do! Think about it. It really is easy to make an RV that reenters from orbit with no heatshield at all, if you are clever about your aerodynamics.

IRL, The re-entry capsules are designed to slow down the craft rapidly during re-entry through aerodynamics. And, no, they're not bad aerodynamics. A brick has bad aerodynamics, a re-entry capsule has very good aerodynamics.

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1 hour ago, ILikeIke said:

The vehicles' center of mass is offset from its axis of symmetry, so by rotating the capsule during descent the spacecraft crew is able to have a small amount of control over the landing location of their vehicle. 

 

I'm pretty sure Orion uses this method too.

 

 

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27 minutes ago, Draco T stand-up guy said:

IRL, The re-entry capsules are designed to slow down the craft rapidly during re-entry through aerodynamics. And, no, they're not bad aerodynamics. A brick has bad aerodynamics, a re-entry capsule has very good aerodynamics.

Depends on your definition of "good". But in KSP 1.1, to get a MK1 command pod landed on the ground you need to be thinking "high drag during reentry" -- or jeb is going to be a little cloud of dust.

Edited by bewing

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9 minutes ago, bewing said:

Depends on your definition of "good".

Does what it's designed to do which is to slow down the craft quickly and stop it from burning up while maintaining the correct angle of attack. The science around re-entry vehicles is really quite fascinating.

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5 minutes ago, Draco T stand-up guy said:

Does what it's designed to do which is to slow down the craft quickly and stop it from burning up while maintaining the correct angle of attack. The science around re-entry vehicles is really quite fascinating.

While I'm old and hate change I have to admit that my annoyance have failed.

My hit orbit, match target, save the sad gits (as in brave Kerbals) and land back on Kerbin design, optimised for 1.0.5 has worked annoyingly well in 1.1.0

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If the craft is slowing down faster when spinning on re-entry that is something wrong with the physics engine, with a perfectly symmetrical craft spinning should result in no change to it's velocity, sounds like the craft might be wobbling slightly presenting the sides of the craft to the force of the atmosphere and the game is applying more drag to the craft...

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On 20.04.2016 at 3:23 PM, RW-1 said:

Speedbrakes, if you have them.

But what kind of return are you doing?  I just hit 1.1 and a few suborbital returns didn't work out for my crew, because if you have a relatively steep descent, you won't slow down enough - either it will burn up - explode, or you'll get through, but no time to get to the safe zone to deploy chutes before you smack kerra firma.

You want a 10-20 degree entry to maximize re-entry heating / energy bleedoff, and then also think about aerodynamics as the others have stated.

I just menage this by install this flea engine, after i used it 50 km or so, than discarded is looked like this funny engines that was attached to mercury spacecraft :D 

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I dedicate this video to all smart space loving nerdy girls with glasses/or not ;-)

Look at her face even 9.9 Gs not spoil her smiley face ;-) 

Val not reached space but collected loot of scientific data , and this is important too.

I just already made aprox 4 suborbital flights.  

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I often spin my craft during reentry, but I haven't noticed any effect on how fast it slows down. The reason I do it is it keeps the Mystery GooTM canisters attached radially to the pod from overheating.

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9 hours ago, Pawelk198604 said:

I dedicate this video to all smart space loving nerdy girls with glasses/or not ;-)

Look at her face even 9.9 Gs not spoil her smiley face ;-) 

Val not reached space but collected loot of scientific data , and this is important too.

I just already made aprox 4 suborbital flights.  

You should do a proper gravity turn. Apart from being more efficient, it will give you a more shallow trajectory, which means you'll pass through more air on the way down, which means more drag and slowing down faster.

For suborbital flights like this one, I usually keep my upper stage attached to the capsule and add some small winglets to the back of the stage (this also means more wings at the bottom of the first stage to compensate, but it's worth it). On the way down, I use the capsule's torque to pitch up. The winglets provide just enough lift and drag to slow me down enough to safely open my parachutes.

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