Orbital Mechanics

Ever learn something and remember the conclusion but not the proof?

Ever talk to someone about it and been utterly certain that the remembered conclusion was true?

Ever wonder when you hang up if that conclusion was a special case in a fictional world and has no bearing on the real world even if you remembered it as so?

Man, I don't want to relearn this just to see if something I haven't used in ten years is real world or not.

So I concede the point to Anglave unless he finds that my memories are correct while figuring out we were talking about.

I'd much rather be stupid than right in this case.

Update:

I had the right conclusion, remembered the wrong reasoning!

I'd remembered that it took less Delta-V to make orbit around Venus than Mars from Earth.  I'd remembered that it took less energy to go down the well towards the sun than away.

Nope.

It does take less Delta-V to get to Venus, but that's because of the Oberth effect.

A neat cartoon with the values illustrated.

Finding this answer without doing calculus is complicated by everyone assuming you want to LAND!  It takes a lot more Delta-V to land on Venus (or take off from) than Mars because Venus is so much larger.

The answers are further complicated by the memories of the oversimplified answers being more readily recalled than the actual answers learned later.  I blame George W Bush for my poor recall.  Additionally, I read a paper once about HOW to do some of this which is not well reflected in the WHAT (which is what nearly all of the explanations are).