Finally turned to math to figure out why I hate the ion drive...

[Fearless Son]

14 hours ago, Cunjo Carl said:

I like the idea, but capacitors are heavy! Even the really good ones only store ~1/3 the energy of the same weight of cheapo lead-acid car batteries. What they lack in lasting energy though they make up for with an insane ability to push sudden power. They're a very kerbal power source.

No kidding.  They would be better suited to a stationary mass driver, like to launch cargo from non-atmospheric surfaces.  

[regex]

The Dawn engine exists so you can have the option to use one in the game, like for people who want to make a "replica" of its namesake. If you don't need it or find it useless then there is no need to use it.

I haven't used one in a while but they're fun little toys if you use additional tools to plan their usage. With the amount of delta-V you can muster using one I have no doubt you could plan a fantastic grand tour of flybys, maybe if you get a contract for that in career mode or something.

[DerekL1963]

43 minutes ago, foamyesque said:

What part of "or" are you not understanding here?

 "You have to perform a plane change burn or a capture burn" is a sentence that makes no sense, it's not possible to understand it - hence my repeated attempts to clarify.  (That and your insistence on specifying expensive ways to perform plane changes.)   You always have to perform a capture/circularization burn whether you perform a plane change or not.

[foamyesque]

42 minutes ago, DerekL1963 said:

 "You have to perform a plane change burn or a capture burn" is a sentence that makes no sense, it's not possible to understand it - hence my repeated attempts to clarify.  (That and your insistence on specifying expensive ways to perform plane changes.)   You always have to perform a capture/circularization burn whether you perform a plane change or not.

Oh, I see. There's some missing context. If I'm putting a scanning satellite in orbit over a body I'm doing so as part of a larger ISRU mission, which is typically destined for an equatorial (or, at most, somewhat inclined) orbit; if I wanted the satellite in an equatorial orbit it could simply piggyback on the main insertion and circularization burns, effectively free given its mass relative to an ISRU landing rig, with no problems. However, since it needs to be in a polar orbit, I detach it on entry into the SoI and execute a plane change there. But that still leaves me with a probe that needs to be able to slow down to achieve a low circular orbit, which is a fairly major dV commit, and ion engines do that in the most compact way, particularly since you need a large pool of EC in order to be able to transmit the scan results anyway.

I dunno why you'd send a scanning satellite somewhere before you needed to land an ISRU rig there. Interplanetary transits are enough of a time sink I like to move as much as feasible on a vehicle, so I need only do it once.

 

Edited February 21, 2017 by foamyesque

[DerekL1963]

Ah... with the context of your overall mission architecture that makes sense.  Ion is about as light as you can get, minimizing impact on your overall mission.
 

22 minutes ago, foamyesque said:

I dunno why you'd send a scanning satellite somewhere before you needed to land an ISRU rig there. Interplanetary transits are enough of a time sink I like to move as much as feasible on a vehicle, so I need only do it once.

I usually use ScanSat (for the science), so I just attach the resource scanner to my mapping bird since it also wants to be in a polar orbit.  (When I'm not using ScanSat's resource scanning mode, but it's wonky.)  If I'm not using ScanSat, I just add the resource scanner to my normal science mission (which doesn't care that it's in a polar rather than an equatorial orbit).

Plus I usually have a ton of missions running in parallel, so even if I do have to send a dedicated resource scanning bird I usually have plenty going on elsewhere to keep me busy.  (Thank heaven for KAC!)

[Tweeker]

There used to be a mod {probably still is} that had a solar sail. I can't remember what it was, (Interstellar?). It would accelerate during time warp. No idea what the accelleration was. I wish i had messed around with it more. 

     

[Streetwind]

5 hours ago, Tweeker said:

There used to be a mod {probably still is} that had a solar sail. I can't remember what it was, (Interstellar?). It would accelerate during time warp. No idea what the accelleration was. I wish i had messed around with it more. 

     

That would be this one:

Though honestly, it's not glitch-free. I prefer simply taking BetterTimeWarp Continued, making myself a 20x physics warp profile, and executing 10-minute burns in 30 seconds.

[DerekL1963]

8 hours ago, Streetwind said:

Though honestly, it's not glitch-free. I prefer simply taking BetterTimeWarp Continued, making myself a 20x physics warp profile, and executing 10-minute burns in 30 seconds.

I just let it run in the background while I do other things like browsing the forums.

[Slam_Jones]

13 hours ago, Streetwind said:

-snip-

Though honestly, it's not glitch-free. I prefer simply taking BetterTimeWarp Continued, making myself a 20x physics warp profile, and executing 10-minute burns in 30 seconds.

I've gotten into the habit (for long burns) of disabling a few fuel tanks and transferring fuel around so that the dV needed for my maneuver is the same as the dV available in  the open tanks.

For example: say I've have 10,000m/s of dv.  I set up a maneuver node that requires 6,000.  I shuffle around fuel and disable some tanks so that my available dV reads at 6,000.  Then, I crank up physics time warp as much as possible and go outside for a while.  It doesn't matter if I come back half an hour after the burn ended - I will still have used the right amount of dV and should be on course

Edited February 22, 2017 by Slam_Jones