Dres full trip and back fuel cost

[Guest]

Does anyone know the best amount of delta V for a Dres round trip?

[James Kerman]

Hello @The Doodling Astronaut, I have moved your question to Gameplay Questions.

[Guest]

28 minutes ago, James Kerman said:

Hello @The Doodling Astronaut, I have moved your question to Gameplay Questions.

actually I realized I posted it in the wrong area so I was wondering when one of you were going to come

Thank you anyway

I'll try not to do it again

[Aegolius13]

Per the delta v map,  looks like 5,700m/s round trip from LKO to Dres orbit.   That's without any aerobraking on the way back. 

 

https://forum.kerbalspaceprogram.com/index.php?/topic/87463-13-community-delta-v-map-26-sep-29th/

[EDIT - read map wrong and used wrong number.   Fixed above]

Edited June 13, 2019 by Aegolius13

[Geschosskopf]

6 hours ago, The Doodling Astronaut said:

Does anyone know the best amount of delta V for a Dres round trip?

Zero, because nobody ever goes to Dres (voluntarily).  All ships bound for Dres are on 1-way trips.  Either they're planting relays there to communicate with MUCH more interesting places further afield or they're black marias taking overly troublesome Kerbals to permanent exile and then serving as their barracks on the surface.  Nothing even bothers doing Science! there because all that you learn is a bummer 

Seriously, the dV map linked above will provide the answer, PROVIDED Dres is in the optimum position when you launch.  The optimum position, which is what the dV map shows, is when Dres will be at the closer of its AN or DN with respect to Kerbin when your ship gets there about 1.25 years after launch, so your ship doesn't need to make a plane change en route.  Unless you've got nothing else going on in your space program and can thus afford to just warp forward until this configuration happens, you'll have to take considerably more fuel.  I'f you have to go at the earliest launch window (which only takes departure angle into account, not inclination or distance), pack about 20-30% more.  I usually build 50% extra into my ships just to be sure and because I sometimes make navigation errors due to drunkenness.  Better too much than too little.

 

[Guest]

6 minutes ago, Geschosskopf said:

Zero, because nobody ever goes to Dres (voluntarily).  All ships bound for Dres are on 1-way trips.  Either they're planting relays there to communicate with MUCH more interesting places further afield or they're black marias taking overly troublesome Kerbals to permanent exile and then serving as their barracks on the surface.  Nothing even bothers doing Science! there because all that you learn is a bummer 

Seriously, the dV map linked above will provide the answer, PROVIDED Dres is in the optimum position when you launch.  The optimum position, which is what the dV map shows, is when Dres will be at the closer of its AN or DN with respect to Kerbin when your ship gets there about 1.25 years after launch, so your ship doesn't need to make a plane change en route.  Unless you've got nothing else going on in your space program and can thus afford to just warp forward until this configuration happens, you'll have to take considerably more fuel.  I'f you have to go at the earliest launch window (which only takes departure angle into account, not inclination or distance), pack about 20-30% more.  I usually build 50% extra into my ships just to be sure and because I sometimes make navigation errors due to drunkenness.  Better too much than too little.

 

I actually looked at a dV map but I don't trust 'em. I always like other people to show their on experience there and back

The rover deployed on Dres and the lander away were it could do damage to the rover. SO I will launch the lander get it into orbit and look at how much Delta V is needed from there. Thanks guys anyway I know people use Delta V maps but I don't like them.

[Geschosskopf]

7 minutes ago, The Doodling Astronaut said:

I actually looked at a dV map but I don't trust 'em. I always like other people to show their on experience there and back

You are wise not to trust dV maps.  They show the best-case scenario, when the target closest to Kerbin and you need no plane change en route, but this is stated nowhere on them.  So like I said, 20-30% more will usually do for non-optimal transfers but 50% more always works and also gives you so lagniappe fuel for stretch goals.

Moho is the classic example of not trusting dV maps.  What the dV maps never say is that this cost is ONLY for a bi-elliptic transfer timed to intersect Moho at its AN or DN with respect to Kerbin.  If you go directly there from Kerbin like you would to any other planet, the transfer burn will be about the same.  HOWEVER, the capture burn will be MUCH more than shown on the map, like 4000-6000m/s, due to your huge relatively velocity when you get to Moho.  Relying on the dV map and going directly to Moho, then being surprised at the huge size of the capture burn, is what has given Moho its evil reputation.  But if you do a bi-elliptic transfer to hit the AN or DN, and don't mind waiting several solar orbits to synch up with Moho at that position, you can usually get close to what the map shows.