Why is my spaceplane veering left?

[SiliconPyro]

If I can get off the runway this thing makes orbit and comes home fine, but on the runway it wants to veer suddenly left at around 90m/s. Anyone know what could be causing it?

Here's the craft file.

[I_Killed_Jeb]

Haven't downloaded it, but 90 m/s is a a really fast takeoff speed IMO. Are your rear wheels close to the CoM? If they're not, that probably explains why you have to build the speed to generate that torque, which in turn overloads those wheels

[DisarmingBaton5]

Try placing your gear vertically so the wheels are not running on an angle. If that doesn't work, place them further outboard. If that doesn't work, place your gear in a configuration that ensures an "upward" position (nose pointing slightly above horizon). If the problem persists yet, strut everything. If that doesn't work, try 4 wheels instead of 3, 6 wheels instead of 5, etc. If all of that fails, you may consider building a new plane.

[Cruzan]

This vid might help you out!

[SiliconPyro]

I moved the rear landing gear to be vertical and much closer to COM. Now when I reach 55m/s I start nosing up gently and at around 90m/s it just lifts off the runway beautifully. I was worried about clipping an engine as I have done many times in the past, but a gentle takeoff worked wonderfully (partially thanks to the much improved SAS).

Thanks for the advice, guys.

[I_Killed_Jeb]

One little additional trick is throw on an "engine saver" landing gear, very shallow so that it's not touching the ground unless you're about to tailstrike

[SiliconPyro]

One little additional trick is throw on an "engine saver" landing gear, very shallow so that it's not touching the ground unless you're about to tailstrike

What do you mean by 'shallow'?

[DisarmingBaton5]

What do you mean by 'shallow'?

Very close to the fuselage/engine; it will hit the ground just barely before your engine and thus save you from a tailstrike RUD.

[Cruzan]

Taking off using Trim (Alt + S) also helps prevent tail-striking by allowing you to gradually pitch up. Just Press Alt+X after you've taken off to reset it.

[SiliconPyro]

Very close to the fuselage/engine; it will hit the ground just barely before your engine and thus save you from a tailstrike RUD.

Okay, I get you. It would be nice if we had a little wheel specifically for this (and for rover wheelie bars ).

Taking off using Trim (Alt + S) also helps prevent tail-striking by allowing you to gradually pitch up. Just Press Alt+X after you've taken off to reset it.

That's a pretty good idea. I managed to get this one airborne just find once I moved the wheels forward, but on more complicated designs, that could really help.

Thanks again, everyone.

[GusTurbo]

Add more wheels to more evenly distribute mass.