quarthinos

I'm pretty sure r4mon is on the list of folks who get early builds. MJ2 worked fine when .20 came out. Seeing as the jenkins build has not changed for several months, I fear something bad has happened.

supersonic is faster than speed of sound in current conditions (and depending on the context, anything below mach ~1.2 is only transonic, not supersonic.) Speed of sound at sea level isn't constant, anyway. Changes based on pressure, temperature, humidity (and maybe other things?)

OK. It's better to launch prograde, then burn prograde on the daylight side of the orbit... So is kosmo-not's post wrong? Or is Olex's webpage wrong? I want details and formulae, not just "it's better!" How specifically do I determine when to burn?

Yes, but the IRL venus probes could use n-body physics, not patched conics. Can you get to Eve launching into a prograde orbit using less delta V than launching retrograde?

So I'm planning a flight to Eve. Is it better to launch directly to a retrograde orbit, or launch to a prograde orbit, then do a plane change to get retrograde?

Or even just for stage N...

I got 6400L into a 300km orbit with no solids. I'm not sure how much "fuel" a solid is considered to be anyway. I used something close to the standard ascent profile with mechjeb (I'd been fiddling with it for another rocket, and I'm not sure it's exactly in the middle). I'll post the craft file when I get home. I had some fuel left in the tanks after the 6400 launch, so I stuck an extra 200L tank on top and hit launch before I left for work. I'm sure that'll get to orbit, but I'm not sure if it'll be a 300km circle. Next up is fiddling with the gravity turn and maybe try some 3m engines, as I'm currently using clusters of 1ms right now. Edit: This configuration gets the 7400L of fuel above the topmost decoupler to a 233 x 300 orbit. Take off the 200L tank, and it'll get the specified orbit.

Extra-Kerbin autolandings have issues. I think mechjeb is not using the correct altitude, so it burns (VERY!) late. Also, orbit's TRANS module is not capable of inward transitions, only outbound. You'll sit in Duna orbit forever and it'll never start a transfer. (The same will happen if you want to go Kerbin->Eve...)

When testing my most recent rocket stack, I've been landing on Minimus' pole to check if I have the dV to get back to Kerbal afterwards. Obviously, if you take off from the pole into orbit, you're gonna end up in a polar orbit. I hope that my current lander will be able to go extra-Kerbal, and I'm simulating the extra dV by landing on the Minimus pole, then taking off, changing azimuth back close to 0, then going back to Kerbal. (I haven't been able to softland at KSC yet because I keep going prograde to get to KSC and then aerodrag stops me from getting the rockets pointed back at the ground )

When HavesteR was discussing the fix he made to the fuel bug, he said that some addons might need to be rewritten.

Umm. How do you go "terminal velocity" going up? Isn't terminal velocity where drag == acceleration due to gravity?

I think an aerospike is hyperbolic. It's engineered so that it's atmospheric pressure acting as the nozzle, rather than some fixed piece of metal. A quick look at wikipedia doesn't say what mathematical shape is used, although the article mentions at least three different ways to do it: A linear wedge (pictures), a torus, and a literal spike (both written). Reading wikipedia at bit more in-depth shows that in the late 90s NASA built a couple for the X-33. It's Isp was 339 at sea level and 436.5 in vacuum. Looking at a spec sheet for the original J-2 (the guts of which were reused for the X-33 prototypes), it got 200s at sea level and 421 in vacuum. So the aerospike was 70% more efficient at SL and 4% more efficient in vacuum. (Efficiency being amount of thrust generated per unit of mixed propellants). And the throttle bug is pretty fierce. Either build with 100% solids, or keep the throttle all the way open all the time.

Except for the altitude change, Isp isn't changed much by throttle setting in the real world, and doesn't change at all in KSP. Remember Isp is a measure of efficiency, so it's mostly dependant on propellant and the shape of the rocket nozzle. It varies with altitude on the non-spikes because a nozzle is optimized for a certain altitude in atmosphere (or for vacuum, of course). Aerospikes were made to give the same Isp regardless of altitude, which is the main way a given engine's Isp varies IRL.

It is in vessel info. On my display, I keep it open and leave it so the title is hidden under Mechjeb's main panel. That keeps thrust, mass and TWR always visible.

He did rewrite the fuel source system, but I'm not sure it will fix balancing issues. Keeping the center of mass/thrust in the correct place requires more logic than just generating a list of fuel sources.