im using constant force to move my homing missile. is there a scripted constant speed only in one direction? so that my missile will move the way it’s facing. 
Just add the constant force component and change the values you need under “Relative Force”. Make sure that all other values equal 0.
You can use a component:
http://unity3d.com/Documentation/Components/class-ConstantForce.html
Which is fairly easy.Or get into scripting:
http://unity3d.com/Documentation/ScriptReference/ConstantForce.html
Which gives you all the pieces, you just have to know how to assemble them.
Theres a couple of lines in the rocket launcher script that you can remove or alter to access these Im pretty sure…
The car racing tutorial shows good examples of force. Be sure to realise the difference between moving by controlling the objects transform(The object itself), and affecting the object through applying forces. these are two different ways for moving things. Try not to mix the two , too much.
Your best bet is knocking over the scripting essentials tut first, and you probably wont get it all to begin with, but it will help you follow other things.
AC
Zzzz…
i’ve been using constant force, but my missile turnes so fast the constant force doesn’t work for making it a “Smart Missile”
Increase the drag on the missile’s Rigidbody, and increase the ConstantForce to compensate.