Is it feasible to use either solid or bipropellant liquid rocket engines to lift off from the surface of Venus?
"Reference datum" air pressure on Venus is around 9.3 MPa; even on the top of, say, Maat Mons, the pressure would be around 5 MPa. Some modern engines have chamber pressures above 20 MPa (e.g. SSME, RD-170), so it seems possible for a rocket engine to work.
Due to the very high ambient pressure, I'd expect the expansion nozzle to be short and specific impulse to be poor. Can the performance specifications of a liquid bipropellant rocket engine optimized to exhaust into pressures from 1 to 5 MPa, using similar turbomachinery to an existing engine, be estimated? Ideally I'd like to get an estimate of the specific impulse curve of such an engine from 10 MPa to 0.1 MPa ambient.
Feel free to handwave away the thermal issues involved in maintaining liquid propellant tankage while waiting to launch from the Searing Black Calm. The goal here is to be able to simulate a rocket ascent from the surface of Venus to stable orbit, in order to answer another question on the site.
I’m well aware this is not going to be the most practical way to ascend to orbit from Venus. I’m not asking if it’s optimal or practical. Please constrain discussion to rocket engines only.
RPA crashes promptly when I ask it to compute performance at 60 bar exit pressure.