Space Shuttle (stock-ish) landing help. (Suspension, wheel placing etc...)

[thevegimobil]

Hi there,

I have managed to build an asymmetrical space shuttle with a cargo bay to take payloads into orbit (finally! it has taken me from about .18 to achieve this). This is with the help of throttle balancers, tweakscale and spaceplane parts plus.

Now whilst i can get into orbit reliably and bring it down to the right ball park or approach (with atmospheric trajectories) i cannot for the life of me manage to get it to set down on the runway nicely.

Now i have quicksaved and reloaded the approach about 50 times over the past two days and i, honest to god, have only landed 2 perfectly. The rest have been catastrophic failures. I get down to about 150 m/s speed and flare up, i fight a slight roll during the flare but usually manage to keep it level. Now as soon as my two main landing gear touch the runway they force the front down and then the craft begins to roll over onto the wings and into the ground, destroying everything inbetween. At first i thought this was because i have the wheels too close and no drogue chute, so i added them (realchutes mod). I have tweakscaled the rear gears so they have good clearance aswell.

Now i am at a loss as to how to prevent myself from crashing every time. I basically need touchdown to be more forgiving. I try to minimize vertical speed as much as i can but it almost never seems to be enough, then if i do it squirms on the runway. I guess my main question is that can i edit the suspension values to give myself a softer landing on the gears to reduce the load and cushion myself slightly? Also are there any mods that can autoland a glider onto the runway taking into account the parameters from when you turn the autopilot on. Mechjeb always nosedives me into the ground.

Any help on this would be massive as i have read many thread trying to solve my problem.

I am using FAR as well.

[Geschosskopf]

Landing at 150m/s is usually a great way to make explosions. It at all possible, try to land at much slower speeds. I like planes that can land at 50m/s or less . Of course, this depends to some extent on the design of your ship, whether you're using FAR, have airbrakes, etc. But in stock air, it's very hard to stall at all.

One thing I always do is put my main landing gear as far outboard as possible, directly under the wingtips. If the wingtips are forward of maingear on the rear of the fuselage, that's OK because they'll still keep the wingtips from digging dirt should the plane try to roll over. The stock airplane wheels are massless so no problems putting them anywhere you want.

[CalculusWarrior]

A stock(ish) space shuttle? Awesome, are there pictures?

My favourite method of landing perfectly on the runway involves placing a flag at the end of it, then setting that as a target from orbit. Using Trajectories, I target that grassy area between KSC and the mountain range. Spaceplanes have a lot of cross-range capability, so there's a lot of breathing room. Then, I get down to ~250-200 m/s in the lower atmosphere, a few kilometres from KSC. Finally, I line up the flag's pink target marker with the 90 degree line. This ensures that I'm coming in due east. After that, it's simply a matter of bleeding off velocity and coming in quite low. This ensures that even if I come in at high speeds, the landing gear are able to take it because there's not a lot of vertical velocity involved. After that, it's a matter of braking hard and hoping I don't run out of runway.

Alternatively (if your landing profile is good), you may just have landing gear issues. If the standard three wheels aren't sufficient, you may want to add more. Try starting the shuttle itself on the runway, then using its engines to pick up speed. It will likely wobble and break apart at some point, but that data will be good, as it lets you know where the issues are. It sounds like that single front wheel isn't enough, so you may want to add a couple of auxiliary gears on the wingtips (to prevent a complete rollover), or just double up the placement on the front, if your body is wide enough.

Hope this helps!

[Progressm]

You probably know this but ensure the landing gear is straight, not on a sideways angle (no camber angle & wheels straight to the direction you're going). The smallest camber angle in KSP causes some very funky landing gear behavior.

That said, may just be that 150m/s is a bit much! If you don't have much of a gliding ratio, you may need to do an aggressive flare quite late to match a lower airspeed with a safe vertical velocity for touchdown.

[Yakky]

You probably know this but ensure the landing gear is straight, not on a sideways angle (no camber angle & wheels straight to the direction you're going). The smallest camber angle in KSP causes some very funky landing gear behavior.

Yes, this is very true. Make sure the gear are straight and not tilted inward or outward. One other adjustment you can try is tilt them slightly back, so that the gear strut extends slightly backward rather than straight down. This seems to help them track straight.

I had a lot of the same problems as you with my "Coming In Hot" challenge: heavy craft, high landing speed, FAR aerodynamics, tall and tippy at landing, and wings that were too small to give it much control. Your success rate of 2 out of 50 sounds about right! It's really hard to do, but is gratifying when you nail it.

(Pics from my efforts. Not sure what your craft looks like, but here you can see the challenging piggish-ness of mine!)

A couple more ideas to try:

You could try two pairs of gear up front, spread out as much as possible, so that you have less tendency to roll sideways after touching down.

You also said that "as soon as the rear gear touch down, they force the front down." That implies maybe they are too far rearward. Try moving them forward so that the craft can balance for awhile on its rear gear before the nose comes down. Real aircraft have the rear gear reasonably close to the center of mass, not all the way at the back.

Lastly, consider using an action group key to disable all your torque modules and maybe all your aerodynamic flaps except the outer-most ailerons the moment you touch down on the runway. It's possible all your control surfaces and torque actuators are contributing some sort of weird roll moment coupling that becomes problematic after the gear hit the ground. Your efforts to correct post-touchdown wobbles may be exacerbating the problem rather than making it better.

Hope these help, and good luck!

[cadaverific]

With FAR landing speeds anywhere between 100-200 km/s are normal and certainly doable. Trying to land at 150 is perfectly fine, especially with a shuttle design.

Assuming you're doing a good approach the first thing that i would recommend it turning off the brakes on your front landing gear. It should help to keep your ship more stable when landing. Next i would look at adding an extra pair of landing gear in the back. This can help braking, ground stability, and distribute weight when hitting the ground. Your 2 wheels could very well be buckling when you hit the runway.

As always, pictures (or a craft file) would certainly help.

[Jimbimbibble]

It's usually best to have the rear gear just behind the CM. Also, having the brakes on at touchdown would cause the symptoms you listed.

[endl]

why dont you try creating enough lift with a wing design that lets you glide into a landing. this way you can aero brake if you have no fuel