Create LH2-powered air-breathing engines

[Kerburettor]

Hi,

My question was probably not asked in the right subforum so I'm re-asking here.

I would like to know how to tweak config files to create an air-breathing jet engine that works on LH2 (from a real fuels mod for instance, or similar) and intake air.

I'm using the Real Fuels mod, Stockalike RF configs and the Solver Engines Plugin.

Thanks

[juanml82]

Nertea's Near Future Aeronautics 

has (or had in the past?) a patch to make the 2.5m Cutlass use LH2. The Cutlass is like a rapier, but you can either use it i just air breathing mode or look at that patch and go from there

[Kerburettor]

Thanks mate. I had managed to do that by adding a few lines in the cfg file in pretty much the same fashion it is done in Nertea's mod, with different values for Isp in the atmospheric/velocity curve sections. What bothers me is fuel consumption. Realistic values for Isp lead to a crazy volumetric flow rate of LH2 and LOx in closed-cycle mode. Obviously, increasing thrust (at constant Isp) is always going to cause my propellant consumption to skyrocket and putting 8 RAPIERs on my craft is bonkers. Next time I play, I'll try divinding the number of engines by two and see if that helps although it will force me to drastically modify my ascent profile due to a much lower T/W ratio.

Do you know of any mod that records data from your flight profile in real time such as thrust, lift, drag, fuel consumption, ... and stores it inside a/multiple file(s) for later analysis?

Edit: I need to mention that, as thrust reaches a peak near the 10-13 km range, my air-breathing LH2 consumption increases nearly 10 fold compared to ground-level flow rate.

Also, the ratio of LH2 to intake air had to be turned on its head otherwise a realistic ratio (cf. this thread) would cause my engines to flame out under minimal throttle. This is ridiculous.

Edited January 7, 2020 by Kerburettor

[DeadJohn]

OPT has several engines that run in any atmosphere. They use liquid fuels by default. Add Cryogenic Engines (or maybe Cryogenic Tanks, a companion mod) and those engines will run on LH2 instead.

You can then reverse engineer what those mods are doing to make your own LH2 engines. I'll guess it's a Module Manager patch but I've never investigated further.