Help with the numbers

[Kyler9437]

I love this game but it is so dishearteningly difficult. I can manage to orbit and I have gotten to the mun and back once but can't seem to do it again. I also can't seem to rendezvous to do rescue missions either. This game needs you to run everything perfectly with little to no room for error. Even the satellite missions you need to be way too precise to actually finish the mission. Its mostly the numbers, I can't make any sense of any of them. I don't really know what delta v is and thats a really important number to know. Sorry if this is a little rambly but I'm just frustrated with the game a little, are there any tools that kind of help take that Dificulty edge off? I have watched most of the scott manly vids and they helped a lot but I'm still struggling to make any progress past where im at. Any one have any advice or know of any tools to help at all?

[gingerfrizz]

try science game..no missions is easier to work out what the bits do..and mechjeb helps I played for a year before getting mechjeb. just watching it rendevous and dock was v helpful in working it out to do solo..

[RoofCat]

delta v is not important at all. Just launch a rocket and see for yourself how far can it go. I have done the delta v math to find out it for some of my highest range ships - just out of curiosity, but it really isn't needed to play the game itself. I have been everywhere without using that math or googling requirements. Delta v means how fast this ship can go starting with 0 on orbit. In theory. There are many factors that can and will reduce your real delta v a lot in flight. Atmosphere drag, long burns off the perfect spot, gimbal burning off prograde, hovering during landings, etc.

Either you add extra stages once yours aren't enough or you fly with nuke engines to all further targets. Nukes can basically reach any body with single stage once on orbit. They just have trouble landing while heavy.


Thinking about simple mass proportions is much easier than doing delta v math with ln(), while the result is all the same. It's all about mass in space flights. Stock game shows you mass while building, click the icon bottom right.
Payload (or upper) stage must be just 1/6..1/12..1/24 from the ships mass at curent stage. Start with 1/8..1/12 and see where it gets you. Engine is roughly 1/12..1/24 too. The rest is fuel - that stuff that gets you further. The higher fuel proportion, the better your reach.
At some point it becomes too slow though, so you can stick to proportions mentioned above for starters. "1/12" on regular vacuum stages (Terrier, Poodle) will have around 4500m/s and will have enough power (kN) to land and lift on all low G (<0.5G) bodies. (1/6 ~ 3700m/s, 1/24 ~ 5600m/s). Theoretical limit is somewhere above 7000m/s for those engines, but you will never reach it. Going below 1/24 is not really reasonable. Extra stage will have better effect. On the other hand going above 1/6 is just stupid. You still need that heavy engine, but it works for a few seconds burning quickly through that tiny fuel amount and then it is wasted mass for the stage and all the stages below it. It can be ok for launch stages though, as for those power vs. mass proportion is more relevant - to be able to lift off at all (at optimal ~1.5 thrust to weight ratio) and there are no stages below them.


Example for a 3 stage ship with delta v included:
Upper stage - command pod, chute and stuff 1t (payload), 0.5t Terrier engine, 4.5t tank - total 6t, payload 1/6 (engine 1/12), delta v ~3700m/s
Middle stage - 6t "payload" (upper stage), 1.75t Poodle engine, decoupler, size adapter, 27t tank - total 35t, payload ~1/6, delta v ~3700m/s (bit more, Poodle is slightly better than Terrier, but tiny bit)
Launch stage - 35t "payload" (middle stage with upper stage), 6.5t Twin boar engine (with tanks deducted), decoupler, 90t fuel tanks (one 36t included with engine) - total 132t, payload ~1/4, and because launch engines have less Isp - just 2600m/s. It will do the main lifting job though as Kerbin orbit requires around 3400..3600m/s. Final push will be executed by more efficient Poodle.

So you have a ship that can send one pilot on a 10 ooo m/s trip. Which is enough to go to Dres or land on outer Jool moons. With a ship worth 36ooo$. You will need small heatshield on return though to be fair. Make some tanks dropable once empty, add a bit more fuel on final stage and boost that delta v to ~12ooom/s and visit Eeloo, Vall and Laythe. Decouple return fuel tanks before landing on target and save some more. You will have to dock and refuel after relaunch, but that will be worth the trouble for far targets. Fuel is heavy and landing wastes it more than anything. You use most of your fuel forwarding fuel in space flight. Which sucks, but can be optimized a bit.


Of course, sending one pilot may be not what you are looking for, but then just add more stuff, fuel and engines. As long as you keep those proportions, it will work all the same. You can simply put 4 of those together for the whole team in a single ship or make it any other way. It will have the same reach with the same mass proportions. Everything is scalable in KSP and space is all about mass proportions. You don't need exact numbers. Everybody builds with some safety margin anyway - for landings and mistakes.

And then single nuke stage can give you 8000..12000m/s. Which kind of kills any challenge.

You can google delta v maps and use calculator(s). But in fact you just take one target after another and improve along the way. Add more stages once needed. And for gods sake - drop empty tanks, that's free gold.



Also, Start - Training teaches you how to fly to Mun (and basically everywhere in space).
In case you wonder - Mun landing needs just around 2500m/s once you reach Kerbin orbit with launch engines. Minmus even less. So much for 3700m/s+ in a single vacuum stage.

[Chibbity]

Get KER mod so you can see your rockets Delta V as you build it.

https://forum.kerbalspaceprogram.com/index.php?/topic/17833-130-kerbal-engineer-redux-1130-2017-05-28/

[Operation40]

you don't need to understand delta v to use it. It's just a number.. Use KER to see that number..

the piece you're missing is a delta-v "map" to figure out *how much* of that number you need, https://forum.kerbalspaceprogram.com/index.php?/topic/87463-13-community-delta-v-map-26-sep-29th/

fyi: there's a dv map for the real solar system too :) these are rough numbers, they don't account for air braking or complicated gravity assists.. but least it is ballpark what you need..

trying blindly until you get a "feel" for the game is just instanity imo.. use KER + the dv map and at least you have some idea where to start.

[RoofCat]

sometimes I get the feeling every person walking the streets knows all about calories, digestion and energy conversion in muscles :)

[GeneralVeers]

Originally posted by Kyler9437:

I don't really know what delta v is

This is what delta V is:

You're in your car, tooling along down the interstate at 30 miles per hour. Yeah, I know, a little slow for an interstate, and also screw the metric system. MILES per hour. Now step on the gas and accelerate to 90 miles an hour. You just applied a delta V of 60 miles per hour.

That's what delta V is.

Any rocket you build has a certain mass, and its engines provide a certain amount of thrust. Point that rocket at something and fire the engines till all the fuel tanks run dry; the rocket's change in velocity is its total delta V.

From Kerbal Space Center, getting into low orbit requires about 4,000 m/s of delta V. From low Kerbin orbit to Mun? 950 m/s. From low Kerbin orbit to intercept Duna? Around 1,200. If you start from Minmus and do a gravity whip to get to Duna? You can cut that to 350.