Reactionless drive ships orbital flight in 3rd ed physics?

[David Johnston2]

Originally Posted by weby

In 3rd edition space there was a thing where low thrust ships with wings could fly to orbit on planets with atmosphere if they had a certain % of their mass as thrust.

It was something like 8% for thin, 5% normal and 3% heavy density atmosphere.
?

Don't think so. Lifting bodies can fly into space provided only that they have enough reactionless thrust to exceed the planetary gravity.