[Space, Spaceships] Total ΔV for Interplanetary Travel

[DaltonS]

Originally Posted by PTTG

You want the sum of the ΔV required to break orbit from the origin, the ΔV used in the transfer itself, and then, yes, the ΔV expended to attain orbit at the destination.

Thanks. This will help.

Originally Posted by PTTG

In theory. In practice, good piloting can reduce the ΔV needed on arrival, and if the destination has an appropriate atmosphere and you have a ship that can handle hypersonic atmospheric burns, you can use areobreaking to achieve orbit at the destination for a fraction of the ΔV cost.

I think areobraking would require a certain level of armor to withstand aerodynamic heating depending on the ΔV you want to shed.

Originally Posted by PTTG

All of this assumes a Hoffman transfer, which is generally both simple and low-ΔV-cost. The downsides are that it requires specific windows to work well, and it's fairly slow.

That's where a One-Tangent Burn orbit calculator comes into play. Unlike a Hohmann transfer, you can adjust the launch windows by adjusting the ΔV used. The second burn has to be done at an angle to the flight path, requiring more ΔV.

Originally Posted by PTTG

If one has very large reserves of ΔV, it's possible to fly from the origin to the destination directly, and I think there's notes on that in GURPS Space. Or Spaceships. Can't remember.

Brachistochrone (literally meaning “shortest time”) transfers are those that use constant thrust throughout the duration of the voyage, performing a 180° rotation halfway to decelerate until coming to rest at the target destination.

Pyramid 3/79: Space Atlas "Halfway to Anywhere"(p.27)

There is even a spreadsheet to go with the article. :) For some reason they missed One-Tangent Burns though.

Dalton “still working on his Mars Semi-Cycler” Spence