/sci/ - Science & Math

Gonna play devil's advocate here...
Yes, the potential-energy gains would be virtually nonexistent, but there are other gains to be had. Most notably, atmospheric pressure near sea level (during those first few thousand meters when oh-so-much propellant is consumed) significantly reduces the rocket's specific impulse and forces designers to compromise on first-stage nozzle size (therefore reducing efficiency at high altitudes as well). Launching from, say, 6000 m, would cut atmospheric pressure in half at launch, significantly improving launch efficiency and allowing designers to compromise less on nozzle design.

This isn't just theory, either; the air-launched Pegasus rocket takes advantage of this effect.

>>3020299
Mark my words, there will NEVER be an airbreathing engine that produces appreciable thrust at greater than ~4.5 km/s/mach 13. Even if you manage to slow the air down enough with your precooler, you'll never be able to accelerate it back up to more than these velocities, seeing how even a pure rocket cannot exceed this.

Chemical rockets are still your best bet for Earth launch; once in orbit, you options open up, but in the end chemical rockets are the most common fallback for heavy applications due to the inherent low thrust/high power consumption of electric thrusters.