I am grumpy but elated (yep, it's another spaceplane comment)

[Wanderfound]

Yah, the one thing I have learned is keep the wheels tucked in just a bit so that they don't strike the two spikes of death at the end of the runway. (But not TOO far, else you veer one way or the other on your runway acceleration.) Anyway, Ritier is safely off to Jool, now I want to fiddle with a smaller plane and the suggestions above about optimizing the ramjet performance. I've always viewed that as a derivative of everything else I am doing, not as a control variable. I feel a bunch of backflips into the VAB coming up.

If you're needing the whole runway to lift off, something's messed up unless you're flying a 150 ton monster. Rear gear forwards or more pitch-relevant control surfaces.

As for veering: are you unlocking the steering on the front gear?

[Wanderfound]

I'm hardly one to criticize, most of my spaceplanes end up closely resembling a pile of parts spread around the apron at the end of the runway. Intact and in orbit has a beauty all its own. Besides, it's very difficult to make spaceplanes that both work well and look good with stock parts, most of the pretty spaceplanes are done with mod parts.

Aesthetics are in the eye of the beholder of course, but: http://forum.kerbalspaceprogram.com/threads/88628-Kerbodyne-D7-Heavy-X5-a-heavy-lift-SSTO-spaceplane

[O-Doc]

I'm guessing you're at orbit with about 60T mass of which 20T is fuel. That gives you roughly 3km/s dV with those nuke engines. Now I can see the craft in question, I would definitely recommend more turbo jets and intakes to supply them. As non-airhogging design you can throw in some engine nacelles in front of those turbojets. Also, more control surfaces is going to help your ascent profile considerably.

Use a poodle engine instead of that skipper, you want the ISP over the TWR. I only ever use nukes on SSTOs but I can see that sometimes you need a little more oomph. Do you burn your rockets with your turbos on to maximise speed before climbing out of atmo?

[James_Eh]

If you're needing the whole runway to lift off, something's messed up unless you're flying a 150 ton monster. Rear gear forwards or more pitch-relevant control surfaces.

As for veering: are you unlocking the steering on the front gear?

But I am. 130T or so fully laden. And yes it's unlocked. Just have to fight the urge to overcorrect when we start to slide one way or the other.

[Wanderfound]

But I am. 130T or so fully laden. And yes it's unlocked. Just have to fight the urge to overcorrect when we start to slide one way or the other.

Any of the control surfaces set as flaps? Might shorten the takeoff and reduce the load on the front gear.

[Laie]

Note the MJ confusion regarding dV. I am happy that it generated some discussion, though.

Can it be that you only ever toggled the engines with action groups and never actually staged? In other words: if you were to hit the space bar right now, would that activate all engines? In that case, MechJeb is understandably confused. It thinks that the currently inactive engines will come into play at some time.

[James_Eh]

Can it be that you only ever toggled the engines with action groups and never actually staged? In other words: if you were to hit the space bar right now, would that activate all engines? In that case, MechJeb is understandably confused. It thinks that the currently inactive engines will come into play at some time.

MJ does very well with vessels where you only use action groups - as I toggle engines (or groups thereof) on/off it changes the dV display accordingly. However where it stops working (and this is certainly no fault of its own) is when you have fuel stowed away in such a way that it can't be pulled by the currently active engines - it figures out the dV based on the assumption that you will drain all fuel available via fuel lines, and then assumes that you will crank up the remaining engines to use up whatever fuel is left. At least that's how I think it works. It can't make the intuitive leap that you are going to manually transfer fuel from tanks that are currently inaccessible by the activated engines.

[FleshJeb]

But I am. 130T or so fully laden. And yes it's unlocked. Just have to fight the urge to overcorrect when we start to slide one way or the other.

I try to use 2 wheels for every 10-15 tons of mass. Otherwise they dig in a bit.

Are your control surfaces limited appropriately? The only one that should have Yaw is the big vertical tail. Other control surfaces set to yaw may be causing it to wallow.

Your vertical tail may not be far enough back from the CoM to provide passive yaw resistance. Mounting a pair of them farther back on the wings may help.

The final warning: MechJeb's SMART A.S.S. never puts me straight down the runway. It likes to drift left. I use plain old SAS until I'm ready to lift off.

[Laie]

That's because the runway isn't straight -- or rather, because someone put a perfectly straight runway on a round planet.

Order a bearing of 90.3 degrees and you'll be fine. Or just do it yourself.

[Wanderfound]

The final warning: MechJeb's SMART A.S.S. never puts me straight down the runway. It likes to drift left. I use plain old SAS until I'm ready to lift off.

Extra warning: Smart A.S.S. is not currently accounting for gimballing roll. Expect your planes to go a bit haywire if you use it.