Search the Community
Showing results for tags 'ratio'.
Found 3 results
Don't you hate it when you have too much fuel/oxidizer laying around? Which you could change the mixture ratio that your engines use (like the J-2 did in real life)? Want no more. Introducing: EMRController With this mod, you can configure your engines to use different oxidizer/fuel mixtures, and have the ISP and thrust adjust accordingly. You can even set up your engine to run in "Closed Loop" mode, emptying your tanks at the end of a burn. This mod does not contain any configurations, but if you use Realism Overhaul, you'll see that the J-2 does have configurations that work with this mod. Download: Github View the Source cfg changes powered by sarbian & ialdabaoth's ModuleManager plugin. Changelog:
Hey! Beginner question here, I recently made my first custom part for ksp, an engine. While making the .cfg I noticed a field called "ratio" in the propellant section. Only answer I've found on google is from the documentation wiki which says it notes how much of a resource is used in 1s. Although, all engine .cfgs I've seen use 0.9 for the fuel and 1.1 for the oxidizer. So, what does that line do and how is it correlated to the overall workings of the part?
In flight, you can open up a nice aero forces display by opening the ALT F12 debug menu, going to the physics tab, then the aerodynamics sub-tab, then checking the "display aero data gui" checkbox. I've noticed however, that the lift:drag ratio numbers seem very poor compared with real-life airplanes. The best I can get is 8 or 9 to one, at 2 degrees AoA, at low speed and altitude. At 0.82 mach and 10km, similar to how commercial airliners fly, best seems to be 2.8 AoA and maybe 5 to one lift / drag ratio. Real commercial airliners are pushing 20:1 at such a point, in fact i'd bet the newest of them, the 787, is over 20 at an "economy cruise" setting. Supersonic , things get worse. At 1.3 Mach, I try climbing higher to use thinner air to compensate for the extra drag. Best results seem to occur at 3.5 AoA and altitudes of 14km or more, I might get close to 4:1. Concorde did 7.5 to 1 at mach 2 and 60,000ft. As we get deeper into the supersonic regime, numbers ebb steadily lower. Above 20km I'll start my final climb to orbit at something like Mach 4 and shutdown engines (needing only to circularise) at Mach 6.6. During this period optimal AoA seems to shift from 4 degrees to 8 or so. At best, I might see L/D display of 2.8, whilst pitching up to high alpha because my craft is overheating can pull it down to 1.6. Reading a little further on wiki, it appears max lift:drag does taper off with increasing mach no matter how high the altitude and thin the air, especially for conventional supersonic/transonic swept designs. However waveriders that rely on compression lift can do better, with designs like the Hypersoar project making 10:1 at mach 6. I guess this is all to compensate for the overpowered nature of jet engines themselves, compared with real life. I still find it a bit weird however, that if my L/D is so poor, why my spaceplanes are so reluctant to actually land. I've long since given up targeting the runway and am quite happy to settle for anywhere on the KSP peninsula or in the shallow seas nearby, usually after flying back and forth across it several times. I guess as we head below 100 m/s our L/D is getting up that of a Cessna light aircraft and we're usually coming in a tad "hot" , also the drag from landing gear, flaps, and jet intakes (with engines off!) is less than it should be .