Space shuttle re-entry

[Lohan2008]

When the (now retired) space shuttle re-enters the atmosphere, it does large figure 8's over Texas to slow it's speed.

Does KSP physics let you do this in game ?? or can you only do retro "burns" ?

Edited October 9, 2013 by Lohan2008

[KatzOhki]

I've done hard pull ups to bleed off speed, not sure about figure 8s though. I don't think the physics are very good.

[Boris_T_Roach]

It did'nt do 'figure 8s' it usually did 4 sweeping turns to scrub off speed as it came in and a final turn to line it up with the runway that was done sub sonic.

I dont see why not if you are bringing in a large heavy shuttle on small'ish wings... but then you run into things like "will the wings break off if I give it too much of a turn at 25 km while still doing 1800 m/sec"

And that makes your kerbals very unhappy

Boris

"We need parachutes for Kerbals"

[7499275]

In KSP you COULD but it would probably drop your speed too rapidly and you would have to burn engines (assuming you have fuel left) to be able to make it to the runway.

And as Boris said, the wings ripping off at 1800m/s, deadly reentry is a mod that will simulate heat and G forces if you wanna make it more interesiting, just sayin

[FITorion]

Not figure 8s.

S turns. Basically it would bank one way and then bank back the other way. But these "turns" are very slight, only a few degrees off it's forward course.

Then when it got down to the landing zone it would pass over the runway and turn completely back around to come in for a landing. This last bit KSP should be able to handle... I'm not so sure about the S turns.

[Moar Boosters]

Sure, you can perform turns to burn speed.

Personally I just angle the nose up a bit if I want to kill speed. Presumably there was a reason the spaceshuttle was unable to do this, probably due to it having the aerodynamic qualities of a flying brick. Chances are anything you build in KSP will handle a LOT nicer than the shuttle did, so shouldn't have problems burning speed by raising the nose. It's pretty much essential if you want to land a plane on Duna, where you'll come in way to fast without it.

[epicbuilder333]

It doesn't always go over Texas doing it's reentry. I saw one time and I live in Oklahoma.

[hugix]

The shuttles angle of attack (something I really miss in KSP!) was swerved from a -50 to a 50 degree bank roll. This allowed the shuttle to create more crossrange thus araving safely at the landing site.

It did however made a circle right before landing to align the shuttle with the runway. This manoeuvre was called the Heading Alignment Circle.

[RoboRay]

Sure. Take any plane up and fly it. Make some turns while holding the nose level and watch your speed decrease.

[BluetoothThePirate]

With a glider, you think of its speed and altitude as being its fuel supply, with the caveat that it needs to get rid of all of it to land. The reentry trajectory is calculated to give it a surplus of kinetic and potential energy so if something unexpected happened it wouldn't fall short (if it hit an unexpected headwind or something.)

[Hodo]

In the stock KSP I doubt the physics will like it much.

With the FAR mod, and your craft is built right, yeah easy, I do it quite a bit in my space planes when coming back to KSC.

[Brofessional]

Well if you calculate it right you don't need to kill speed, you can just come straight in for the landing. Plenty of times I've overshot and had to do a U-turn or loop back around though.

[SkyHook]

Well I will say that with FAR, figure 8s are not really necessary. I control my approach to the runway with altitude. Stay around 30k and float until you get close enough to nose down, lose a LOT of speed, and land before you stall out

[Astral_Nomad]

The "figure 8s" you are talking about are actually called "S-Turns". Its a kind of aerobraking that the shuttle does using it belly to bleed off speed. As far as I know, KSP atmosphere isnt integrated to that sophistication as of yet.

[Kosmo-not]

The space shuttle had to be pitched up at a 40° angle of attack to use the heat shield effectively and slow down at a proper rate. Too little pitch and the shuttle would spend too long in reentry and burn up. Too much and you generate too much heat for the heat shield to withstand. So, they kept the shuttle at about 40° AOA.

The shuttle generates lift throughout reentry, so the shuttle was rolled to be able to control rate of descent and altitude. This again is due to getting the shuttle down in speed before burning up. If you go too low for your speed, you generate too much heat. Too high and you heat up for too long. The "S-turns" are needed to keep the space shuttle on course.

[Runboy]

It IS possible to decrease your speed by doing figure 8s,but make sure that they (The figure 8s) are as sharp as possible,to expose as much of your drag-forming wing.

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[Mr Shifty]

The space shuttle had to be pitched up at a 40° angle of attack to use the heat shield effectively and slow down at a proper rate. Too little pitch and the shuttle would spend too long in reentry and burn up. Too much and you generate too much heat for the heat shield to withstand. So, they kept the shuttle at about 40° AOA.

The shuttle generates lift throughout reentry, so the shuttle was rolled to be able to control rate of descent and altitude. This again is due to getting the shuttle down in speed before burning up. If you go too low for your speed, you generate too much heat. Too high and you heat up for too long. The "S-turns" are needed to keep the space shuttle on course.

It's important to note that the shuttle kept its AOA at 40° even when banking. But banking was absolutely necessary in order to keep descending. Even with a 40° pitch, the shuttle's lift vector still pointed mostly up. And when it hit the thin atmosphere at 80km going Mach 23 it generated enough lift to counteract gravity and pull it back into a ballistic arc above the atmosphere. In order to maintain the 40° angle of attack, but point the lift vector away from the sky, they had to do steep banks (up to 80°), alternating left and right in order to maintain course toward the landing site. This was all controlled by the guidance computer; the commander didn't take control until about 25 miles from the landing site, at an altitude of about 15km (10 miles), at which point the orbiter was going less than Mach 1.

In KSP this is all difficult to simulate because Kerbin is such a small world. Orbital speed is about Mach 6 instead of Mach 23 like on Earth. You can probably pretty easily get away with just using pitch to control your descent and don't stand much danger of skipping back out of the atmosphere in any circumstance.