Delta-V to Dres orbit and Back

[Rockhem]

What is the required delta-v to dres orbit and back? i have designed a propulsion module that has 9.5k delta-v with payload, is this enough? and what is the exact amount needed?

[SkyRender]

There is no "exact amount needed", because 1.) there are a lot of variables to consider and 2.) even with optimal conditions, you still have a "fudge factor" to consider due to not having the infinite thrust necessary to meet those conditions.

Here's an average delta-V map I made a while back, however. As you can see, on average it takes around 950+350+800=2100 dV to get out to Dres and circularize around it, and 800 dV to return, giving you 2900 dV on average to get to Dres. This can go up quite dramatically if you don't fire when Dres is in phase and/or perform poor plane correction maneuvers. But 9,500dV is more than enough for a simple Dres orbit-and-return operation.

[Rockhem]

i have reduced my delta-v to 5.5k to give me a margin of error. I have stripped 50 tons off my vehicle, lol.

[CalculusWarrior]

Oddly enough, adding more fuel and boosters makes your ship less efficient, and if it's too big, you run the risk of it breaking in half!

[SkyRender]

Oddly enough, adding more fuel and boosters makes your ship less efficient, and if it's too big, you run the risk of it breaking in half!

This is correct, and why "mothership" missions are actually pretty damned inefficient when you get right down to it. Better to send up a separate refueling craft to your destination along with your ship that's doing a mission, so that neither ship needs to pack that much fuel. Plus, it lets you leave the other one in orbit around your target body for whatever orbital purposes you may have for it. Automated science lab, perhaps?

EDIT: Out of curiosity, I did a bit of a test via Kerbal Engineer Redux. I had two setups: one was a lander with drive stage to take it to Dres (the lander had enough to land, return to orbit, and get back to Kerbin with a 30% margin of error). The from-Kerbin launch weight was 170 tons.

Then I built a pair of ships: the exact same lander without a drive stage (meaning it can reach Dres but needs to refuel once it gets there), and the drive stage modified a bit to be more multipurpose. The final weight: 195 tons across both ships. If I'd made the refueler as minimalist as the drive stage from the all-in-one ship, that'd drop the cumulative weight between the two to about 180 tons.

So yeah, there's not a lot of weight difference between the two vessels. Technically the all-in-one is slightly more fuel-efficient, but it's also considerably less versatile.

Edited April 27, 2013 by SkyRender

[tavert]

The number for Dres in that diagram is at least a few hundred m/s too small.

[WilliamW2010]

On 4/27/2013 at 4:42 PM, Rockhem said:

What is the required delta-v to dres orbit and back? i have designed a propulsion module that has 9.5k delta-v with payload, is this enough? and what is the exact amount needed?

9.5k is enough please send me a download link

[Randazzo]

6 hours ago, WilliamW2010 said:

9.5k is enough please send me a download link

That was almost 9 years ago mate, you might peruse the spacecraft exchange if you are looking for some inspiration

Edited January 18, 2022 by Randazzo