Engine for quicker circularization

[Biggen]

I'm curious what people are doing when needed tons of dV to circularize orbits for a planet like Moho.  I see it can take between 1500 dV to 3500 dV depending on when you launch.  Nukes are fine for getting there, but damn, their TWR sucks.  Are people supplementing their nukes during circularization burns with chemical rockets (e.g. Poodle) or do you just live with a long burn time to complete the orbit?

Edited February 3, 2017 by Biggen

[InterCity]

You usually just make a long burn. Bigger engine means bigger fuel tanks and let's face it, you don't want that extra weight on interplanetary missions. 

Of course, no one is preventing you from making a giant ship assembled in orbit and sending it there...

[renhanxue]

For interplanetary, I think most people just come to terms with the five to ten minute burns. If you think the nuke is bad, you should try the ion engine.

The actual lesson here though is that building very small rockets is actually really cool and interesting. There is a point where bringing along three tons of nuke engine becomes a very unappealing option, and then you can start doing zippier rockets with small liquid engines.

[DD_bwest]

for most i can get the burn done within its SOI no problem,   Moho is a different beast.   When i am mounting massive missions to land in all moho biomes, you need to bring extra fuel for all those landings.  when you start to add everything up, your Dv takes a major hit and your forced to move higher up the ISP ladder.  I will often end up on ions, since they have such insane ISP.  But since you are so close to moho you can attach a couple extra iondrives and your solar panels will most likely still have enough juice to power them all.

but the main key with ions, is to start from outside the SOI.    do your best to lower the relative velocity before you get to it.   try to match inclination a bit, and lower your solar AP as much as you can as well.  

[Tyko]

Building on what @renhanxue said...send smaller rockets.. I ended up sending my lander, lander fuel and extra LS as a separate launch. It was waiting in Moho orbit when my crew arrived.

[Aegolius13]

3 hours ago, Tyko said:

Building on what @renhanxue said...send smaller rockets.. I ended up sending my lander, lander fuel and extra LS as a separate launch. It was waiting in Moho orbit when my crew arrived.

Isn't that pretty much the same as just putting more engines on one big craft, though?

 

 

5 hours ago, Biggen said:

 I see it can take between 1500 dV to 3500 dV depending on when you launch.  

And that's if you get the transfer perfect.  If you screw it up, even a little, you can easily end up with a capture burn of 5km/s or more.  You can always start your burn before shortly hitting Moho's SOI - use a combination retrograde and radial burn to get your orbit to look more like Moho's.

 

You may want to look into the alternative method of going to Moho:

1.  Forget about phase angle-based launch windows.

2.  Eject from Kerbin while it's at AN or DN with respect to Moho's orbit.

3.  Perform your plane change burn along with your ejection burn, for that nifty Pythagorean discount.  Set your periapsis around the sun equal to Moho's orbit.  

4.  You will probably not get an encounter with Moho.  If not, while at your periapsis, do a retrograde burn long enough that you will hit Moho on your next orbit.  How big this burn needs to be depends on Moho's relative position in its orbit.  

 

There are some more detailed explanations around the forum.  This takes longer (in game terms), but it's cheaper overall, and more fool-proof.  A nice side benefit is that your Moho injection burns tends be to quite small (I think I've had as small as 500 m/s), so it's much easier to manage with a low TRW.