Asparagus staging - help?

[Mitchz95]

Hello, I'm trying to build a Tylo lander that uses asparagus staging, but I'm having some trouble with the delta-v count in the VAB. For some reason, instead of breaking down how much is consumed based on the tanks draining, it assumes the vast majority of delta-v is being consumed in the same stage where I fire the engines, with most of the drop tanks being measured as 0. I'm pretty sure the fuel paths and decoupling order is correct based on my testing.

Hopefully the fuel flow path is clear, but if not...

Stage 02 fires the engines;

Stage 03 drops the outermost tanks;

Stage 04 drops the 4:00 tanks;

Stage 05 drops the 8:00 tanks;

Stage 06 drops the 10:00 tanks and attached engines;

Stage 07 drops the 2:00 tanks and attached engines.

This leaves the center tanks and engines to burn out as normal.

Based on my experience with asparagus staging in the past, stage 02 should have the lowest listed delta-v (and burn time), and stage 07 should have the highest. I can't tell if I'm overlooking something or if this is a limitation in how KSP2 calculates delta-v.

[cubinator]

My Duna lander which uses two alternating sets of engines displays zero deltaV. I think for anything more complicated than a traditional stack you're better off calculating it yourself for now, at least in the VAB. 

In flight, I wouldn't trust that you'll be able to make the game show how much fuel you have left in each tank. 

[Meecrob]

My personal advice, ditch the cupola, and put the 2 seat lander..."Tuna Can"? on the bottom of your lander, take off the ladders, and have a ring of fuel tanks instead of like "wings" or whatever you have now; that is waaaay too complicated.

[Scarecrow71]

On 12/31/2023 at 8:59 PM, Mitchz95 said:

I can't tell if I'm overlooking something or if this is a limitation in how KSP2 calculates delta-v.

I don't trust KSP2's ability to correctly calculate dV in the VAB (or anywhere else in-game, for that matter).  I consistently have seen where the VAB will calculate one value, then at launch I'll see something else, then if I reload the game I get completely different values.  I think there is a floating decimal point error somewhere in the math, but I'm not a dev so that's just a wild speculative guess.

On 12/31/2023 at 11:04 PM, Meecrob said:

ditch the cupola, and put the 2 seat lander..."Tuna Can"? on the bottom of your lander

If some is good more must be better, right?  If that's the case, go with the cockatoo and bring all the kerbals!

[whatsEJstandfor]

Not to hijack the thread but I haven't been able to get asparagus staging to work in general (at least not in the way I did it in KSP1) because if I put, say, 6 decouplers in symmetry around my center stage, I can't move individual decouplers to their own stages; it seems like I can only move the decouplers to other stages all as one unit.

In your example, how'd you get those decouplers in their own stages? Did you just do 2x symmetry and place multiple sets of them?

EDIT: I must not have looked very closely at the image; I see now that yours isn't symmetrical, so I'm guessing you didn't use radial symmetry, so you bypassed the problem I have.

Edited January 2 by whatsEJstandfor

[Mutex]

47 minutes ago, whatsEJstandfor said:

In your example, how'd you get those decouplers in their own stages? Did you just do 2x symmetry and place multiple sets of them?

That's how I do it. And then use fuel-lines to join the tanks together (don't bother trying to enable fuel-crossfeed in the decoupler, it doesn't work well).

[hatterson]

I've had nothing but issues with the dV calculations in the VAB. Apparently the order you  place parts affects it and can cause issues. The in flight ones seem a bit better, but they still seem to have some quirks when using asparagus staging.

So far I've been building it non-asparagus first, see what it says for dV, and then moving it to asparagus and adding 10-30% dV depending on how close to mass/TWR limits I am. That's had some unfortunate consequences when my guesstimate is off (like the rescue mission I'm sending to Tylo right now), but it works alright as a workaround.