Puff (the MAGIC dragon lives up to its name)

[Korizan]

So I was playing around with a tug to get a station to Mun from a Kerban orbit.

Tried multiple different engines with the "Terrier" coming out in the lead

Well until I started looking at the Mono-propellent engines then things got REALLY interesting.

So the baseline tug was putting out a Delta-V of 180 m/s Terrier before I added some tanks.

For fun I added in (4) O-10 "Puff" Engines and the Delta-V jumped to 836 m/s.

So I added on (4) Stratus-V Tanks and now I have 1,077 m/s and now on paper I can push the station to Mun and put it into orbit.

And now I have to ask, really, what am I missing here ?

[Randazzo]

Apparently, you have way too much monoprop on that tug.

Unless of course you're just going to go with the monoprop engine design, in which case, lose the LOX.

[Korizan]

Apparently, you have way too much monoprop on that tug.

Unless of course you're just going to go with the monoprop engine design, in which case, lose the LOX.

A valid point

So I took 3.8t worth of Mono and 4 Puffs came up to 3,920 Delta-V

And 3.8 t worth of normal fuel with a Terrier and that came up with 4,946 Delta-V

Now just with that the Terrier wins based on Delta-V

However when you start looking at the size of the craft well not even remotely close.

Might have to look into this a bit more.

[GoSlash27]

A valid point

So I took 3.8t worth of Mono and 4 Puffs came up to 3,920 Delta-V

And 3.8 t worth of normal fuel with a Terrier and that came up with 4,946 Delta-V

Now just with that the Terrier wins based on Delta-V

However when you start looking at the size of the craft well not even remotely close.

Might have to look into this a bit more.

The monoprop tanks have horrible mass efficiency and the O-10 has average-to-poor Isp. This means that the right chemical rocket will almost always yield a lighter overall stage.

The exception is where the thrust and DV requirement is super low. In this case, you can't find a chemical rocket and tank combo small enough to do the job efficiently.

An example from .90:

Chemical Tylo descent stage vs. monoprop.

Best,

-Slashy

*edit* remember that missions are not planned around which engine can give you the most DV, but rather which engine gives you the needed DV in the smallest and cheapest total package.

Edited May 26, 2015 by GoSlash27