Hybrid balloon / vehicle approaches
Saw a recent news item about JP Aerospace. They are working on a two step to orbit approach. The basic plan is to put a large lighter than air (LTA) craft at 200,000 ft, and then accelerate it using a ion thruster to reach orbital velocity.
So I was interested in how this would work, and what the basic parameters (mass, thrust, time) are for approaches of this type.
The benefit of starting from a high altitude is very low air pressure. A balloon can provide steady support so a low thrust vehicle has time to accelerate.
Orbital velocity is roughly 9500 m/s.
What size solid fuel rocket would be required to put a 10 kb payload into orbit?