New aerodynamics

[diegzumillo]

Hi all

Planes have been my long time hobby in KSP. I learned how to make planes and SSTOs in vanilla KSP (pre 1.0) and in Ferram, now I have to learn how to make these in new KSP. So that's fun! I decided to make this thread so we can share our discoveries on how the system works.

At the moment I see the potential for this new system to allow even more powerful SSTOs, but it does seem harder. It seems harder than Ferram as well, but I don't know for sure yet, as Ferram had an entire panel of information that helped design stable planes and here we have nothing.

First thing I noticed is that my planes tend to flip. The center of mass has to be as close to the nose as possible, which is hard if you have all your engines at the back.

[locustgate]

I've only launched 1 plane (mk1) to test aerodynamics.......my tail fin(avr8 winglit) exploded when I hit 1k at 5-10km, both of my wing control surfaces(fat-445) exploded when I hit 1.5k at the same height range, my plane did manage to get to space. I was able to land and survive with a splashdown.

First glance it seems that your weak point are your control surfaces. Use airbreaks to VERY quickly go from 2km/s to 200 m/s, even without control surfaces you'll survive.

Edited April 27, 2015 by locustgate

[eddiew]

Rapid ascents seem to be your friend now... you can not hang around at low altitude since speed will kill you with fire.

If anyone works out how to get back from orbit... let us know! I came in from 75x50km and overheated

[Wjolcz]

The atmo still feels a bit soupy at low speeds. You can easily take off at about 40m/s. But at least we can go fast at low altitude so I'm pretty happy about that.

[frizzank]

Put your center of mass as close to the center of your fuel tanks as you can, you may need to add ballast. Make sure your Center of Lift is about a meter behind your center of mass and stays there even if your fuel tanks are empty. This will increase your stability.

[SRV Ron]

Not only aircraft, but rocket launches and parachute recovery is vastly altered by the new atmosphere. A single RT-10 pod combo no longer reaches 38,000 meters in Career, but barely makes 24,000 meters no matter the thrust setting.

[Wjolcz]

Rapid ascents seem to be your friend now... you can not hang around at low altitude since speed will kill you with fire.

If anyone works out how to get back from orbit... let us know! I came in from 75x50km and overheated

You cant go with spaceplanes like you do with capsules. Start the descent sooner and do S-turns.

[locustgate]

Rapid ascents seem to be your friend now... you can not hang around at low altitude since speed will kill you with fire.

If anyone works out how to get back from orbit... let us know! I came in from 75x50km and overheated

Try Airbreaks.. I had 4 on my small plane. I was able to do a survivable splashdown, with only 2x turbojets and 4x airbrake.

Edited April 27, 2015 by locustgate

[NathanKell]

You need to come back like the shuttle, belly first, not nose first.

[Space_Can]

At the moment I see the potential for this new system to allow even more powerful SSTOs, but it does seem harder. It seems harder than Ferram as well, but I don't know for sure yet, as Ferram had an entire panel of information that helped design stable planes and here we have nothing.

That's not exactly true, you can receive interactive displays showing lift and drag through the debug menu, I believe they are under the aerodynamics panel.

[zxczxczbfg]

Unfortunately the new aero seems to have fudged something important: The standard arrangement of MkI pod, Mk16 parachute, and 1.25m heat shield, which by all rights should be stable, isn't.

[diegzumillo]

That's not exactly true, you can receive interactive displays showing lift and drag through the debug menu, I believe they are under the aerodynamics panel.

Can you give me more information? I can't see anything.

- - - Updated - - -

Ohh! debug menu as in actual debug menu doh. Hm, it shows information but it doesn't seem to change when I change my plane. I'll have to look into it.

As for progress, I did managed to make an SSTO already. A very simple one, just a rapier and no wings (vertical liftoff) so it's not exactly the point of the thread but still...

Another thing we should keep in mind is that with this new model anything remotely aerodynamic generates lift! and if we are making SSTOs, chances are we are making very fast planes, so we really want our planes to be as thin as possible. My point being: you can make a plane without wings basically. Large wings means drag.

[locustgate]

Can you give me more information? I can't see anything.

- - - Updated - - -

Ohh! debug menu as in actual debug menu doh. Hm, it shows information but it doesn't seem to change when I change my plane. I'll have to look into it.

As for progress, I did managed to make an SSTO already. A very simple one, just a rapier and no wings (vertical liftoff) so it's not exactly the point of the thread but still...

Another thing we should keep in mind is that with this new model anything remotely aerodynamic generates lift! and if we are making SSTOs, chances are we are making very fast planes, so we really want our planes to be as thin as possible. My point being: you can make a plane without wings basically. Large wings means drag.

http://i.minus.com/jbrYZynYNnYcn6.png

I've been unable to get a normal rocket into orbit, around 10km it just spins out of control. It seems I finally got a hang of space planes only to lose rockets.

[Cirocco]

Unfortunately the new aero seems to have fudged something important: The standard arrangement of MkI pod, Mk16 parachute, and 1.25m heat shield, which by all rights should be stable, isn't.

you don't need a heat shield on the MkI pod, it has one built in. And a simple pod + chute works perfectly for me in early career. Hell, it's the ONLY thing that works in early career.

[xXIndestructibleEVAXx]

you don't need a heat shield on the MkI pod, it has one built in. And a simple pod + chute works perfectly for me in early career. Hell, it's the ONLY thing that works in early career.

They do not have a heatshield built in. On only 100%, heat is very low, but on 120%, it is dangerous, so you need a heatshield.

[zxczxczbfg]

you don't need a heat shield on the MkI pod, it has one built in. And a simple pod + chute works perfectly for me in early career. Hell, it's the ONLY thing that works in early career.

I'm in Sandbox at 100% heating, the pod explodes quite spectacularly if I try to de-orbit it without a heat shield (no, it doesn't come with one by default). My question was, why isn't it stable?

[Cirocco]

They do not have a heatshield built in. On only 100%, heat is very low, but on 120%, it is dangerous, so you need a heatshield.

allow me to clafiry: it seems that the MkI pod has an extremely high temperature tolerance when coming in with the rear end facing forward. If it comes in nose-first, it burns up and dies. So while no, it doesn't have an ablative heatshield built in, it does seem to have a high tolerance on the bottom. This is mostly empirical evidence though: every time I tried to bring down a MkI with some science equipment or fuel tanks and engine below it, descent went fine until it flipped over, pod-first. After that, the pod (and the rest of the craft) had about 5 seconds to live. If I use only the pod + chute on exactly the same descent, everything is perfectly dandy and pod comes down without any overheat at all. I have yet to try sending in a pod alone, nose first, but it's late now and I have work in the morning. Will test tomorrow

[Stormweaver]

I'm in Sandbox at 100% heating, the pod explodes quite spectacularly if I try to de-orbit it without a heat shield (no, it doesn't come with one by default). My question was, why isn't it stable?

Someone decided that the heatshields should be physicsless parts for whatever reason.

It's easy enough to fix - go to your KSP folder, then gamedata/squad/parts/aero/heatshield, go into each of the three config files, find the line that reads PhysicsSignificance = 1 and change the 1 to a 0.

[zxczxczbfg]

Someone decided that the heatshields should be physicsless parts for whatever reason.

Whoever thought that was a good idea needs to have their snack privileges suspended. Physicsless parts add drag (according to the debug menu) but not mass, making it horribly aerodynamically unstable.

[Enorats]

The heat shields are totally wonky. They have mass according to their tooltip, but don't alter your center of mass as seen in the hanger. However, they DO alter your center of mass in the "world". Putting a heat shield on the end of a balance tilts it towards the end the heat shield is on when you "launch" the balance (You can try this, build a balance using structural parts). They DO have mass, and it DOES affect your plane/rocket. It just doesn't show it in the hanger.

[diegzumillo]

Just noticed something interesting. My plane was going pretty high (at the third level of atmosphere, forgot what number that is) and pretty fast (300m/s surface) and my air intake was starting to run thin, so I was preparing myself to turn off the jets before they flame out. Here's the strange part, my air intake started growing again. I immediately thought I was losing altitude but nope. I believe the air intake system takes speed into account now (did it before? I never noticed).

Edited April 28, 2015 by diegzumillo

[Kerbonautical]

Just noticed something interesting. My plane was going pretty high (at the third level of atmosphere, forgot what number that is) and pretty fast (300m/s surface) and my air intake was starting to run thin, so I was preparing myself to turn off the jets before they flame out. Here's the strange part, my air intake started growing again. I immediately thought I was losing altitude but nope. I believe the air intake system takes speed into account now (did it before? I never noticed).

I'm pretty sure it's always been a factor. The more speed you carry as you get higher the longer you can run off the atmosphere, or at least that's how it always seemed to me.

[diegzumillo]

Real physics behaves like that but I had the impression KSP had only angle of attack and altitude influencing. Oh well, no matter.

[diegzumillo]

There we go! one SSTO on the new system, finally.

Maneuvering the plane is very difficult so the only way I found of reaching orbit is to pick an angle of attack from the take off and stick with it. In this case it was 30.

I'm pretty impressed with the new system. Just as we would expect in real life, the working design is long and thin. Drag really is making a huge difference. The nose of the plane is now sacred! the only thing that goes there is a cone, if you want your plane to follow a straight line. Maybe.