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Hohmann Shmohmann - who else uses high energy transfer courses?


nadreck

What sort of interplanetary courses do you set?  

225 members have voted

  1. 1. What sort of interplanetary courses do you set?

    • None - I don't go beyond Minmus
      6
    • All my interplanetary flights are the most fuel efficient possible
      70
    • I sometimes launch when things aren't at their most opportune, but all my orbits are elliptical
      85
    • I launch whenever I want, but look for the least energetic orbit at the time I am ready to go
      38
    • I look for the fastest orbit I can get with my fuel budget, I put the hyper into hyperbolic
      17


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Bah, poll is butt -- What of those of us who usually mostly Hohmann, but have been known to go full torch ship just to get back from Minmus? (Well, not full torch ship, as burning all of that xenon would've been annoying, but cutting an eight hour transfer into 3 by ignoring hyperbolic trajectory warnings.)

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28 minutes ago, FancyMouse said:

It's not interplanetary anyway so doesn't count?

Erm, 'pretty sure doing the thing in question in a situation where one hardly at all needs to falls pretty well within the spirit of the question; and arguably as a rather extreme example thereof.  In fact I would've burned harder, but I was a bit worried about hitting the atmosphere before finishing the braking burn and so losing my solar panels.

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Personally it depends on the situation.  If the orbit alignment is a tad off and i dont feel like timewarping a few years then ill launch then even if it means a bit more fuel used.  that said, i generally go for efficiency since it makes no sense to waste fuel (and overengineer everything because of that), so most of my ships have ~2000-4000 dV, which is adequate to go 1 way to most planets of interest, even if you use a bit more fuel due to inefficiency.

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Yes, I will usually try to find a "shortcut" rather than waiting for a transfer window. Case in point, a recent Kerbin--Jool transfer 300 days from the optimal Hohmann window:

7b9fyDC.png

Solution here was to make a burn from Minmus orbit (only 218 m/s) to go inward, nearly to Eve altitude--then burn outward at solar periapsis to catch Jool. Looks like I'll save about 300 days at the cost of only a few hundred dV (not counting capture--but then again you can see from the KER readout I have a lot of margin :) 

Transfers like this are not to hard to come up with when you consider there always must exist some solar altitude from which the Hohmann window for your target is open--so, just fly there and you're all set.

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Since I started on Realism Overhaul I`m just happy to be able to get there. I have no choice but to use the most efficient course, even then I still have my fingers crossed.

Managed to fly by venus and return data, fly by mars without data but have not yet managed to fly by mercury

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3 hours ago, John FX said:

Since I started on Realism Overhaul I`m just happy to be able to get there. I have no choice but to use the most efficient course, even then I still have my fingers crossed.

Managed to fly by venus and return data, fly by mars without data but have not yet managed to fly by mercury

^^^ This

I tend to be more "Launch and be Lazy" in Kerbin mode, but RSS, eh, not so much.  It's tough enough getting a Mars Habitat and Transfer vehicle into LEO  - I tend not to throw them out into deep space without a bit of forethought about a viable transfer window and. RSS caused me to discover the KAC transfer window alarm - after two years of regular play! Jeeze!

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It depends on what you mean by "most fuel efficient possible" and "most opportune".  For example, fuel efficient launch windows to Jool occur at intervals of just over one year, but some of these require more Δv than others.  The really good launch windows occur at intervals of about 11 years.  I always perform my transfers at the opening of one of the launch windows (and at the most optimum time within that launch window), but I don't sit around for years waiting for the best of the best to occur.

For Jool, the difference between the best and the worst launch windows might be only 200 m/s or so.  However, for some planets the difference can be >1000 m/s.  In the latter case I'm likely to pass on a particularly poor launch window and wait for a more opportune one to arrive.  It depends a lot on the size of my payload and how big of a rocket I need.  If I can realize dramatic savings by waiting, then I'll wait.
 

Edited by OhioBob
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6 minutes ago, OhioBob said:

For Jool, the difference between the best and the worst launch windows might be only 200 m/s or so.  However, for some planets the difference can be >1000 m/s.

This is why I always pack at least 5.5km/s one-way for a Moho trip.

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On 3/21/2016 at 6:27 PM, QuesoExplosivo said:

My ships that use the Kraken drive routinely take extremely high-energy trajectories in order to have low transit times (10,000 m/s delta-v to Jool, for example). My other, more sane ships use normal transfers.

Is there still a functioning Kraken drive? I thought it broke in 1.0.

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I'm doing a timed challenge right now (Get all the Science...a race) and I'm learning some new concepts here.  I've always gone for the most efficient windows, and waiting was never an issue.  Now I can just pack on a horde of Mammoths and do nasty hyperbolic burns everywhere.  Just worrying now about stopping once I get there...

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11 hours ago, Jarin said:

Is there still a functioning Kraken drive? I thought it broke in 1.0.

Yes, there is, but it's quite unreliable (that's why only a few of my ships have it). It will often randomly stop working, or worse, cause uncontrollable spinning (and subsequent Rapid Unplanned Disassembly). The design is still the classic "micro landing legs through structural plate."

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Wait, there's another option than Hohmann???

Seriously though, it's pretty much all I use. I really want to play around with different methods though... I've never done a gravity assist from Eve to get to Minmus or anything like that. I really wouldn't even know where to start.

I just circularize, make a transfer node, and drag it until I get an encounter.

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I fly when I want to..... Jeb is always right behind me on this... fuel is not an issue... and if it is, then we go somewhere else.

Seriously... going beyond Minmus scares the crap out of me.... so I don't... not till I am good and ready....

As for Jeb... I chain him to the flag pole outside the space centre till he calms down. Leaving him some Scooby snacks helps.

 

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I usually tweak them into "sweet spot", where transfers doesn't take so long and dv requirements aren't too big. 

But when I was playing with KSP Interstellar, oh boy, that was a whole different story. I managed to get an encounter with asteroid hurtling outwards from the Sun at 5km/s at 5 times distance of Eeloo in 163 days.

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  • 2 years later...

I go to other planets when the transfer window is open. I may not do the most efficient burns but I try and keep my required Delta-V low. Also my orbits are always on escape volocity of the planet I am going to, getting moon encounters (either using the Mun or the moons around the planet I am going to) to get a better orbit can get a bit to fiddly with menuver nodes for my liking.

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On 8/22/2014 at 6:15 PM, Franklin said:

You should probably add another option for those who are so dedicated to not giving a damn about efficiency or accuracy that they think launch windows are what's on the side of the observation tower.

 I never cared about launch windows because I'm too stupid to figure that out. I just floor it and hope I have enough fuel.

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I use optimum Hohmann transfers for inner planet unmanned missions. - With TWP I can usually get to within 100-200m/s of my transfer budget.

I use faster not-quite-Hohmann but still elliptical transfers for manned missions because I use USI Life Support, so time away from home and supplies matter. When I'm sending probes to outer planets I'll usually choose faster paths because you can shave a lot of time off with only moderate increases in DV budgets.

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2 hours ago, Kerbital said:

 I never cared about launch windows because I'm too stupid to figure that out. I just floor it and hope I have enough fuel.

Pretty much what I do too.  When I first started, I would break Kerbin's SOI, then set up a maneuver node for the intercept downrange...sometimes over a year later... which really isn't much different than waiting on Kerbin, except your kerbals go insane sooner.

Since I don't play career, I've never given much thought to efficiency.

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