Grr... I am so ready to flip the whole computer sideways! I have spent over 10 hours trying to make this silly plane get somewhere, yesterday, we made it to orbit! 74,000. Remaining dV m/s = 0. I took your advice, added Pilot Assistant, reduced wing area, got rid of the liquid fuel tanks for rocket fuel only, and the Wildcat (KW), LV-T30, and LV-T45. But no success. I have the stock turbojet that is good up to ~Mach 3.0 (more like 3.3), I don't turn on the rockets until 30,000, I have the intake build aid so that I can really stretch the turbojets up to 30k by reducing throttle to keep the intake air above 100%. What the heck is wrong? Why does it weigh so much? What's it's deal? I need way more dV to get into a polar orbit (because thats where I placed my space station, that needs rescue xD). It really grinds my gears that I can't get this, I feel like a Kerbal noob but I have designed amazing rockets with super high efficiency launchers... I just cant seem to wrap my head around it. Maybe i'm piloting the SSTO incorrectly? I see the provided information about a PID tuner, but I'm not sure how to use one or what the adjustable PID options in Pilot Assistant do... I have just been changing max AoA for the pitch control as 10* is too low when you're up at 20,000. I followed Wanderfounds storyboard type advice which was very useful for pilotting tips, unfortunately I cant try out the attached demonstrator as I don't have shock cones or wingstrakes. But I do have most of the C7 wing parts which can mimic them... I have all of the 300 science boxes. I am attaching photos (with more useful info, like COM, COL, dCOM ) of two versions, the 2nd of them where the crew cabin (which weighs 2.0t) has been moved closer to the centre of mass. Please let me know what you think -- Lastly, could be piloting problem, or SSTO design flaw, but in high altitude (passing through 25,000 , and especially after engaging rocket engines and closing intakes etc) the plane has HUGE difficulty staying in a straight line and it takes all my might and RCS to keep the bugger straight! When using RCS build aid it informs me that the main engine is applying torque to the COM for whatever reason, I assume it's because the plane isn't perfectly symmetrical and there is greater weight on one side than another.. I tried using the new smaller cargo bay (just for holding batteries, RCS, essential to flight things, and moving different weight around to try to offset the torque number but it's still very hard to fly straight.. Anyways, thanks again for all the help, I really appreciate it and I'm thankful again in advance! Oops, I forgot dCOM, and i'm aware the front gear on 1A is too far back xD Will fix now... I am linking the ALBUM instead of posting the pictures in the post as it is often screwy. http://imgur.com/gallery/2RwZt