Exactly. The described mode of operation does not really compute. Transition from wing-lift atmospheric flight to orbit requires A LOT of additional energy, so the plane taking off from a runway and then boosting itself to orbit does not seem physically possible. Launching a smaller orbital vehicle from a large carrier plane is another matter... but this would simply be an airborne ballistic/orbital launch, something much different from X-37B that stays in orbit for months and actually more similar to recent American commercial attempts (cf. the White Knight).