Plane spinning on duna for no reason + Creepy White Thing O_O

[JiWint]

Since my previous "discussion" was moved to questions,I prefer not to spam and just edit an useless thread to make some use of it!

Meet the Duna Ion Rover

This one was completely tested at Kerbin.It had absolutely nothing wrong,takes off and touches down like a princess.

But now,after 2 hours of trying to get to duna,I've achieved it *see photo*

And,it was not successful... When I try to land this buddy,it starts spinning LIKE A HELL (spins on vertical axis).

It happens ~8000m :|

Anyone have any idea what can be terribly wrong?

And I saw a creepy white *steam* comming from the surface of duna. Here's a topic about what I saw :| http://forum.kerbalspaceprogram.com/threads/39760-Creepy-stuff-on-Duna

Edited October 4, 2013 by JiWint

[spectrhz]

I made an amphibious Kerbin capsule rescue system that could land and take off from water. I've found that the only (reliable) way to take off out of the water is with a VTOL. Otherwise you have a permanent boat. I'll post pictures when I get back to my main machine.

[JiWint]

I made an amphibious Kerbin capsule rescue system that could land and take off from water. I've found that the only (reliable) way to take off out of the water is with a VTOL. Otherwise you have a permanent boat. I'll post pictures when I get back to my main machine.

I'll try vtol when I'll land on laythe ^^ thanks for advice

[Starwhip]

I think your problem is part clipping resulting in gyro Kraken, or a serious center of mass error.

[JiWint]

I think your problem is part clipping resulting in gyro Kraken, or a serious center of mass error.

The speed was too big ^^ I was flying at <900m/s.

BUT.

I saw a creepy thing...It was some kind of white steam comming from the surface of duna (clicked f9 instantly...) And it is not a bug,as you see,I use ion engines,so no smoke from engines that crashed a wayyyyyy before.

Here's a guy who experienced the same http://forum.kerbalspaceprogram.com/threads/39760-Creepy-stuff-on-Duna

[Geschosskopf]

This one was completely tested at Kerbin.It had absolutely nothing wrong,takes off and touches down like a princess.

But now,after 2 hours of trying to get to duna,I've achieved it *see photo*

And,it was not successful... When I try to land this buddy,it starts spinning LIKE A HELL (spins on vertical axis).

It happens ~8000m :|

Anyone have any idea what can be terribly wrong?

Since you're going to all this trouble already, you need to get in on my "Flying Duna AGAIN" challenge. Check it out . In any case, Duna is THE most challenging place to fly because there's just barely enough atmosphere to make it possible. Everywhere else is a doddle in comparison.

http://forum.kerbalspaceprogram.com/threads/50619-Flying-Duna-AGAIN

Anyway, if I understand your problem correctly, you've got instability in yaw. The cause of this is the complete absence of a vertical fin and rudder. Such surfaces are pretty much required on Duna due to the thin air. On Kerbin, you can get by without them because the air's thick enough that you can get yaw stability from the side of the fuselage.

On Duna, you need at least 2 vertical fins to get enough yaw stability for SAS to keep the plane flying straight. You also need rudders, which I recommend NOT putting on the vertical fins but on the wing trailing edges so as to minimize the amount of roll they induce. Flying wings do work on Duna but I've gotten better results from conventional designs with a tail structure on the fuselage behind the wing.

Also note that one of the major challenges of flying on Duna is landing. First off, the bulk of Duna's surface is 2000-3000m above sea level, which corresponds to about 15000-20000m on Kerbin. If you don't have an extremely low wing loading (as in huge wing for little weight), you can't fly slow enough at such altitudes to land safely. In my experience, landing at any speed greater than about 60m/s is a guaranteed crash. This is due to several factors. First, there's no such thing as level ground on Duna; it's all sand dunes, so if you're going any faster than this, you'll definitely have problems with the terrain. But because the air's so thin, you need LOTS of airbrakes acting for a LONG time to slow you down significantly, even if you have enough wing to fly that slowly. And then when you touch down, the wheel brakes have reduced effectiveness due to both the low gravity and your huge wing not wanting to quit flying, so you again start having terrain issues. Anyway, I'm thinking you might need more wing on your plane, too, besides vertical surfaces.

I recommend that you do your Duna testing with HyperEdit in a separate save game, which is the simulator. This way, you can teleport the plane into Duna orbit and test everything about its flying from deorbit to landing and then trying to take off again. Once you've got something that can do all this on Duna, the next challenge is getting it off the ground on Kerbin. Anything that has enough wing to fly successfully on Duna will pose significant aerodynamic problems during launch on Kerbin .

I currently have a functional plane on Duna taking 2 Kerbals on a tour of all the anomalies. It works but it's a pretty clunky. Maybe you can do better. The thread below shows what it's doing and also the long design process it took to make it happen. I went from the sleek flying wing jet in the 1st post to something that looks like a WW1 bomber by the end, all because I didn't know how hard flying Duna really is.

http://forum.kerbalspaceprogram.com/threads/43871-The-Kethane-Travelling-Circus-EPISODE-15-The-D-OH-Continued

[UH60guy]

I'll try vtol when I'll land on laythe ^^ thanks for advice

Not to hijack the thread, just wanted to point JiWint over to another thread I had put out for questions on how to build sea planes. I can't get VTOL to work, but I can reliably get a low part count <10 ton sea plane flying. I'm building it to take to Laythe as well.

[Moar Boosters]

How fast are you going when you hit 8000m?

Duna's atmosphere only really starts at about 10,000m. Above that it barely has any influence.

I'm guessing your plane just can't keep control when it encounters the stresses involved in atmospheric entry. There's a few things you can try. The first thing sounds crazy, but it often works.

Sometimes planes like to fly backwards when aerobraking at extremely high speed. If you try and enter the atmosphere forwards, the drag will try and pull it round so it's going backwards. Eventually the drag wins, and that starts a spin. The solution is to enter the atmosphere backwards, and then turn the plane around when you're down to a sensible speed. I'm not sure this will work on Duna though, because you've only really got about 10km of usable atmosphere it's hard to turn around.

If that doesn't work, the plane needs redesigning. You don't really have sufficient control surfaces. You need a tail with a vertically mounted control surface for proper yaw control, and you need another set of control surfaces along the length of the plane. Either a tail section, or nose canards will give way more control. Just having the single set of flaps means that the moment your nose gets lifted by atmospheric pressure, you'll start to flip because there's nothing to put downforce on the nose. If you had canards there, they'd put downforce on the nose if it tries to pitch up and prevent your spin.

When a plane pitches up or down it pivots on a single point, and if you only have a single control area, it's going to be really difficult to stop that pitching. Having 2 means you can control it much better. It might fly ok on kerbin in the thick atmosphere, but Duna is much less forgiving as the control surfaces don't provide as much influence with the thin atmosphere.

[JiWint]

-snips -

How fast are you going when you hit 8000m?

-snips- /QUOTE]

Thank you guys for answers.Thanks to kerbals who saved the progress before landing. I still have a LV-N and Skipper engine,so I'll only detach them when I reach ~30 m/s (I hope it will work)

Any ideas about white smoke? I saw it when i was landing with ion engine ._.