Voyager Quest

[New Horizons]

Spoiler: COMFIRMED

BP

Launch

Powerburns

 

[New Horizons]

Oh yeah forgot to ping Altaïr

 

[New Horizons]

I'm very sorry

Spoiler

if I just pinged you, Mooncrasher, but maybe you could check this?

 

[ASC]

be patient, man..

 

[Altaïr]

That's all good. Congratulations, Mooncrasher will give you your badge.

You could even have done better by replacing the Kolibri engine by a Valiant on your third stage (even if you'd have to remove a bit of fuel to stay below the mass limit) and by making the first stage smaller and giving the fuel to the second and third stages. But it does the job

 

[New Horizons]

You could even have done better by replacing the Kolibri engine by a Valiant on your third stage (even if you'd have to remove a bit of fuel to stay below the mass limit) and by making the first stage smaller and giving the fuel to the second and third stages. But it does the job

I didn't want to waste fuel, but, I felt like saying, "Look ma, i did the vOyAgEr qUeSt."
Also It was like, a long burn, but while I was designing the rocket, I thought that i should use an efficient engine for that last stage.

 

[Altaïr]

Also It was like, a long burn, but while I was designing the rocket, I thought that i should use an efficient engine for that last stage.

The reasoning is good, but the Valiant is precisely the most efficient. What I mean by that is that it has the highest specific impulse, so it's the one that saves the most fuel.

I generally illustrate it that way:

If you build this, both side have the same thrust so the "vehicle" won't move. But the Valiant side consumes less fuel despite providing the same thrust. So in the end:

This is what I mean by more efficient, at equal thrust it will be more durable.

 

[ASC]

valiant engine depletes its fuel an bit later than its kolibri engine

 

[Catalyst_Kh]

Fuel efficiency has another important parameter to consider.

Look for this two designs:

Second ship (the one from the right side) will get more acceleration for the same fuel used. Because it needs to push forward less weight.

And if we simply reduce amount of fuel in first ship (the one from the left) to make weights even for both - then first ship will have even less acceleration, since it lost fuel for nothing.

Plus you also need to carry out the entire small ship to its destination by some other bigger ship, and since the ship is lighter on mass due to smaller engine - the process of carrying out itself will use less fuel too. Starting from the very take-off from Earth already.

Often even big ships will actually use less fuel with Valiant engine, than they would use with Frontier engine instead. Though by "pure numbers" Frontier is more fuel efficient. But this "extra fuel efficiency" will be all wasted, when you need to simply burn more fuel to carry out the much bigger mass of the bigger engine itself.

How much big (heavy) the starting ship needs to be to benefit from bigger (but more fuel efficient) engine, instead of wasting more fuel to carry out that bigger engine - that depends not only on the starting ship size (mass), but on the ending ship size (mass).

For example if we have ship, which is 200 tons at the start and it will be 100 tons at the end (since other part of the ship is payload), then Frontier engine will be better. And if the same ship will be only 20 tons at the end - then Valiant will be better, since Valiant will get more acceleration for the same "180" tons (minus empty tanks weight) of fuel used.

So, Valiant "inefficiently" burned the whole "180" tons and still was more efficient at the end (giving more acceleration for the same fuel), than more efficient Frontier instead.

The difference in weights between Kolibri and Valiant is smaller, so the ship size when Valiant becomes better than Kolibri is also smaller. But it is not that small as one might think only by looking at how much fuel the engine needs to burn to get the same sum of thrust as another engine - not even close to that.