I’ve been messing around with trying to piggy back satellites to orbit with a mk2 SSTO. (Think how the SR-71 carried the drone, except the plane gets to orbit before launching the payload) But it seems putting even a small mk1 size space craft on the back causes some ridiculous drag. I built the launcher plane first and it blasts through 440 m/s without breaking a sweat. But with the mk1 craft piggy backed on, it struggles to hit 300 m/s. I know cargo bays have been thought to be an issue but I have none on either craft.