Minmus fasttrack, anybody else doing this?

[magnemoe]

Then going to Minmus and have fuel to burn I tend to go faster than the Hohmann transfer, spending an 20 m/s on the 920 m/s burn take you there in 3 days. 
Yes both the plane change and orbital injection will be more costly so say 200 m/s more with good safety margins. You can set up the entire run with nodes before burning so its low risk. 

Main issue is that its a bit hard to set up, I use mechjeb to set an hohmann, then add 10-30 m/s and move the node backward until I think I have an decent trajectory, then I use mechjeb intercept target at 20 km to get an correction burn. If it don't look good I move the burn node and try an new intercept

[samstarman5]

I'm sure there is an actual sentence here, but I am not seeing it.

If you are trying to argue for the merits of burning straight for Minmus without establishing orbits beforehand, that is fine and dandy in sandbox where resources are limitless on Kerbin.  But in practical application, that is actually a dumb way to go.  Without drilling gear, storage, and refinement, every drop of fuel you bring with you is all you get.  Burning it haphazardly just to get there faster is less fuel to have for the return trip.  Remember, getting to Minmus to Kerbin is one thing, but to get back to Kerbin requires you to take away all the lateral velocity you acquire having landed on or orbited Minmus.  That's less fuel to have for corrections in case you end up coming into Kerbin too steep, or you may end up coming in too shallow which means you skip right out and have to spend more time waiting for the next re-entry.

The fastest way to get to Minmus practically would be by using the Mun to kick you out to it, which requires just the right window to achieve.

[magnemoe]

No, I enter orbit first, however I do an longer burn than the standard Hohmann transfer to get to target faster one who would send me interplanetary after an Minmus flyby. 
Bonus is faste travel time, down to 3 days with an 15-25% dV increase, the problem with going to Minmus is that you go so slow at the end.

And yes the first Minmus science missions did not use this, as you say more fuel wasted is less biomes visited. 

Going directly would actually save fuel many real world moon or interplanetary probes do direct burn without an stop in LEO, however this is pretty complicated to set up.
 

[cubinator]

The Apollo missions did this to reduce demands for food and life support; A Hohmann transfer to the Moon from LEO takes about four days, but by burning a little more fuel in the TMI TLI burn they trimmed it down to just three.

[regex]

Haven't done it myself but it's legit and useful (and not at all "dumb") if you're willing to bring along the extra fuel for it.

I understand the whole "efficiency over everything" mentality around here but I also believe it kills creativity and interesting missions; really wish people here were more open to encouraging and exploring different mission architecture and planning.

Edited May 16, 2016 by regex

[AbacusWizard]

In the stock game time hardly matters so speed isn't important... but with a life support mod it becomes vital. I can certainly see this being useful for (e.g.) sending a rush delivery to a colony that's running low on supplies, or a rescue mission to a stranded crew.

Edited May 16, 2016 by AbacusWizard

[Kerbin vonKerbal]

10 minutes ago, regex said:

Haven't done it myself but it's legit and useful (and not "dumb") if you're willing to bring along the extra fuel for it.

I understand the whole "efficiency over everything" mentality around here but I also believe it kills creativity and interesting missions; really wish people here were more open to encouraging and exploring different mission architecture and planning.

Yep. Sometimes the best way to do it is slap some parts together, hit the space bar, and wing it.

[wumpus]

It would be tricky (but possible) to align the Mun and Minmus to save more than 100m/s of delta-v, but the planning required scares me (that's assuming the Mun can kick you that hard).  You need 100m/s more transfer to Minmus, but you should be able to reduce the capture burn by coming in at an angle form the Mun.  I wonder how efficient you can make it (and how much coding it would take to find the launch windows you could do it on).

There was a whole "fastest to the Mun" challenge.  I think people were doing it under one hour in real time (I think Scott Manley made videos of his attempts).  No reason not to go quickly to Minmus, but also I'm not seeing why I wouldn't do it efficiently (well, as efficient as possible without sweating launch windows) and just hit warp.  WARNING: trying to reduce time down to minimal requires building rockets that barely fit in the VAB.  Expect to build things similar to wackjob and using asparagus after asparagus of Saturn-sized boosters if you want to go for records/challenges.  No idea if the new GUI fixed all the old problems that got magnified when filling the VAB with boosters.

[StrandedonEarth]

Once, when using TAC Life Support, I was running low on supplies so I had to do an extra burn to hurry up back to Kerbin from Minmus before the crew died, shaving several days off and coming in hot!

Edited May 17, 2016 by StrandedonEarth

[suicidejunkie]

I once swapped from a Hohmann transfer to a direct flight, when my bus with TACLS picked a few too many crew for the first time and then noticed it was down to 10% oxygen roughly halfway through the trip.  I burned an extra 800m/s to reach minmus in the 4h30m I had left, and then burned the rest to slow down to a parabolic trajectory so Bill could rendezvous with a fresh can of air and 6 tons of landing fuel using a rescue vehicle he put together from debris parts and his KAS drill.

[Superfluous J]

I don't do this method but I frequently target not the ideal hohmann location for Minmus but instead the AN or DN, and burn up more so my ship falls back down into that node (or reaches it more quickly on the way up) right as Minmus is wandering by.

I don't think this is enough loss of efficiency to justify even thinking about, and the savings in (real-life, me-at-the-computer) time not having to warp or set up alarms in KAC or worry about mid-course corrections is well worth those "drops of fuel."

[Norcalplanner]

I'm doing higher energy transfers to and from Minmus these days, but it's largely because I'm running a 6.4x game with Kerbalism. There are both life support and radiation considerations that encourage a swifter transit, especially if you've kept the craft light with minimal shielding.

[Waxing_Kibbous]

I would love to see an image gallery or video of this method, from LKO to final Minmus orbit.

[Norcalplanner]

I'm going to play later tonight - I'll take some pics.

[Jetski]

You can do the same burning to Jool, just jump the window by a few days, burn a little longer, and shave years off the transit. I've launched an "efficient" rocket at the perfect window, warped a year to the next window, and sent a second rocket on a fast track to beat the first ship there. Down side of this (minmus also) is its a little harder to slow down. Can be set up with nodes easily.

[regex]

4 hours ago, Kerbin vonKerbal said:

Yep. Sometimes the best way to do it is slap some parts together, hit the space bar, and wing it.

Well, that's not actually the point I was trying to make, but vOv

[Norcalplanner]

3 hours ago, Waxing_Kibbous said:

I would love to see an image gallery or video of this method, from LKO to final Minmus orbit.

Here's an album.  Not the most efficient, but it gets the point across.  A little bit bigger burn during the initial transfer cuts the travel time down significantly. 

And for the record, I'm running SpaceY, Fuel Tanks Plus, and SMURFF at 0.5 lever.  Makes for some higher delta V than stock.

 

Edited May 17, 2016 by Norcalplanner
Added mod note

[MarvinKitFox]

3 hours ago, Jetski said:

You can do the same burning to Jool, just jump the window by a few days, burn a little longer, and shave years off the transit. I've launched an "efficient" rocket at the perfect window, warped a year to the next window, and sent a second rocket on a fast track to beat the first ship there. Down side of this (minmus also) is its a little harder to slow down. Can be set up with nodes easily.

The cost of a fast-track transfer is not in the getting there, as a very few m/s of burn at Kerbin makes a huge difference, but in the stopping once you get there.

Cutting Kerbin-Minmus transit time in half needs only about 35m/s more to get there, but about 200m/s more to stop.

 

Eve, Duna and Jool provide an alternative though.

Burn your fast-track transit, and then use aerobraking to assist in the slowdown.

[ag3nt108]

Time isn't really a resource in KSP, you can simply accelerate time to suit your play style.  Fuel on the other hand is finite.  I don't understand the supposed advantage the OP is stating unless were talking saving a fraction of a few minutes during to the 'warp to this point".    I suppose if you have some kind of life support MOD installed 3 days might make a difference between life and death.  I don't use such mods personally.  Minmus missions I orbit before planning an intercept but for the Mun I will often burn right at it from a 75km Apo.

[Streetwind]

If you play with Outer Planets Mod, you will quickly come to appreciate these "high energy transfers"... especially since BetterTimeWarp is not updated yet...

[Kerbin vonKerbal]

8 hours ago, regex said:

Well, that's not actually the point I was trying to make, but vOv

Haha I understood the point you were trying to make, I just didn't quite elaborate on my agreement with you. Oops.

[magnemoe]

7 hours ago, ag3nt108 said:

Time isn't really a resource in KSP, you can simply accelerate time to suit your play style.  Fuel on the other hand is finite.  I don't understand the supposed advantage the OP is stating unless were talking saving a fraction of a few minutes during to the 'warp to this point".    I suppose if you have some kind of life support MOD installed 3 days might make a difference between life and death.  I don't use such mods personally.  Minmus missions I orbit before planning an intercept but for the Mun I will often burn right at it from a 75km Apo.

With mining fuel is infinite, also then launching an slapped together rocket you need an decent margin during launch, why not use the extra fuel. 
Time is only an factor if you need to do contracts or train kerbals before an interplanetary launch window. 

[cantab]

8 hours ago, MarvinKitFox said:

The cost of a fast-track transfer is not in the getting there, as a very few m/s of burn at Kerbin makes a huge difference, but in the stopping once you get there.

Cutting Kerbin-Minmus transit time in half needs only about 35m/s more to get there, but about 200m/s more to stop.

 

Eve, Duna and Jool provide an alternative though.

Burn your fast-track transit, and then use aerobraking to assist in the slowdown.

Agreed with this. The ejection burn for an "express" transfer is usually only a little more than a Hohmann - in fact I've gone to Mun and Minmus on such express transfers without even meaning to! But the capture burn is what bites more.

And since KSP 1.0 aerocapture became a lot more difficult. It's virtually suicide to even touch Eve or Jool's atmosphere at interplanetary speeds, but using Duna or Laythe may be viable.

[Mastikator]

3 days doesn't sound like much when going to Mimimus but I've tried this very thing on Duna.

1 set of probes was sent on a perfect efficiency trajectory.
1 set of probes was sent at about 200m/s faster at a slightly more radial trajectory. It arrived over a 100 days earlier. It used more fuel but if it had been a space ship with crew it would probably be more efficient (since I use TAC life support).

[Kerbart]

8 hours ago, ag3nt108 said:

Time isn't really a resource in KSP, you can simply accelerate time to suit your play style.  Fuel on the other hand is finite. 

Unless your play style does consider time to be a resource. In my career mode I try to reduce stress for my Kerbals as much as possible. That rules out any Minmus missions in a Mk I, and if I can cut 10 days of travel time on a round trip mission then the fuel price might be worth paying it.