So, I installed MechJeb, still fail to travel to distant planets

[OptiSTR]

So... Before I installed MechJeb I managed to land 2 probes on Eve and Duna (including Eve moon on the way as well).

Then I installed MechJeb and tried to use the same ship design (except instead of a probe core I used capsule with Kerbals)

and to land on Moho...

MechJeb burned more then 2000dV to fly from the Sun orbit to Moho encounter...

Basically I ran out of fuel before even getting into Moho orbit, not to say landing on it and then flying back...

Am I missing something? How is that 2800dV (after getting into Kerbin orbit) with 2 Nuclear engines is not enough to land on Moho and return back home?

[Psycix]

Mechjeb isn't perfect.

It usually gets the job done, but experienced pilots can do it better.

Though in your situation I'd guess the phase angles were off and MJ took a less than economic trajectory.

EDIT: The poster below me has a better point: Your numbers are not correct. There is no way you can make it to Moho, land, and back with <3K dv.

Take a look at the delta-V map.

Edited November 10, 2013 by Psycix

[DMagic]

This probably isn't the right sub-forum for this. But look around for delta-v charts or google interplanetary trip calculators.

2800m/s is nowhere near enough delta-v for Moho. It's barely enough to get you on a course for Moho, but you'll need somewhere between 2000-5000m/s more just to get into orbit around Moho. Then another 1500m/s for landing and taking off, and another 2000m/s for returning to Kerbin. Moho is one of the hardest destinations to reach, so a capsule that was good enough for Eve or Duna won't cut it.

[OptiSTR]

This probably isn't the right sub-forum for this. But look around for delta-v charts or google interplanetary trip calculators.

2800m/s is nowhere near enough delta-v for Moho. It's barely enough to get you on a course for Moho, but you'll need somewhere between 2000-5000m/s more just to get into orbit around Moho. Then another 1500m/s for landing and taking off, and another 2000m/s for returning to Kerbin. Moho is one of the hardest destinations to reach, so a capsule that was good enough for Eve or Duna won't cut it.

Woah... hard to imagine how big of a rocket I need to place 5000dV of fuel into orbit around Kerbin...

[Seret]

Check out this delta-v map. You'll need about 3000ms^-1 to get from a solar orbit to Moho orbit and another 1400ms^-1 to land.

5000ms^-1 isn't a crazy amount of fuel if you're using LV-Ns on a fairly small craft and are happy to refuel in space.

[Tarrow]

tried to use the same ship design (except instead of a probe core I used capsule with Kerbals)

That'll have added a couple of tonnes of mass to your vessel, decreasing it's total deltav unless you added more fuel to compensate.

MechJeb burned more then 2000dV to fly from the Sun orbit to Moho encounter...

Do you mean here you're flying from Kerbin, outside it's SOI to a solar orbit, then aiming for Moho? Your Moho intercept burn should be occurring in Kerbin orbit, taking about 1750m/s of deltav to make an intercept (checking my savegame the next launch window for that deltav to Moho is about 20 days away). More fuel would be required for orbital burn, reentry etc so a 5000 m/s total deltav budget for the trip isn't particularly unrealistic. LV-N's (or addon parts with a similar ISP) are good for that kind of thing if you don't mind the low thrust to weight ratio

[LeFudge]

It's the extreme inclination... and it's proximity to Kerbol... and the lack of atmosphere... And yeah MechJeb isnt the greatest, i used it for a bit just to see what it could teach me. The auto docking and rendezvous functions, yeah how about no, often they just put me on a suborbital/some other ridiculous trajectory. Maneuver nodes and a little bit of knowledge about orbital mechanics is the best way.

[Superfluous J]

Yeah Moho is like KSP hard mode. Don't assume ANYTHING about it. I don't even use launch windows to get there and sacrifice time (the time it takes to get there for me is about triple, or 1.5 orbits instead of .5. Sometimes it takes 2.5 orbits) for fuel (I use as close to the minimum as I can) by launching not during the Hohmann window but instead when Kerbin and Moho's orbit planes intersect.

Edited November 11, 2013 by 5thHorseman

[Traches]

Woah... hard to imagine how big of a rocket I need to place 5000dV of fuel into orbit around Kerbin...

The trick to getting a lot of dV isn't building big, it's building small. Build your probes and landers as light as you possibly can.