Playing Stock

[ANWRocketMan]

Hi there,

I installed a stock install of KSP today(besides some essential tools such as Kerbal Engineer, Enhanced Navball + Docking Indicator and Editor Tools. Now, I usually play with FAR, KW Rocketry, AIES and MFT and recently with rescaled Kerbin. Now, however, I have some questions:

Question #1: The delta-v... Oh the delta-V... I just can't get stuff into orbit. I struggle so much with adjusting my rockets to stock aerodynamics etc. What are some tips to keep my rockets looking realistic but still be able to lift my payloads?

Question #2: I just built a 50 ton payload launcher(for my Duna lander and ascent vehicle). Now, I can just just get this thing into orbit. But I'm not enjoying my launches as I normally do with FAR and so on... They just wobble and flex so much. The thing is strutted so much I'm surprised it hasn't collapsed into a black hole yet. I'm out of ideas... I have struts between every single tank and decoupler and engine. I have struts between the bottom stages and the payload, I have struts on my lander engines and my capsule, I have struts. Struts... struts, struts, struts! How can I make launching a pleasurable experience as I used to have with my mods?

Kind regards,

ANWRocketMan

[capi3101]

1) With a 1.2 TWR on liftoff and a 4% payload fraction, you can get stuff into orbit with one stage. Pretty much the same goes no matter what kind of rocket you're building - though it's 8% payload fraction and around 1.5 TWR for onion staging, 15% payload fraction and 1.6-1.7 TWR for asparagus. Basically, build your payload first, then put it put on the pad without a booster. Go to the map screen and get the mass, then go back to the VAB and start designing the booster around what you discovered. Keep the gee meter right at the top of the green meter as you go.

Example - say you've got a thirty tonne payload. If you wanted to launch it on an SSTO rocket, you'd need something that had a mass of around 750 tonnes (30/.04 = 750). You know automatically that you need a launch thrust of 8829 kN or so (750 * 1.2 * 9.81 = 8829), so six Mainsails. Six mainsails weigh 36 tonnes, your payload's thirty, from 750 tonnes that leaves 684 tonnes (750-36-30 = 684), which you then divide into seven stacks (a centerline and six outboard, the engines would go outboard and you'd run fuel lines from the center to outboard); each stach would therefore need 97.7 tonnes of fuel. That's two orange tanks, an X200-32, and an X200-16 in each stack. Add whatever other accouterments you'd like (RCS and a probe core for deorbiting, winglets, nose cones, etc). Oughta do the trick. You can generally build simple SSTO boosters for payloads up to about 45 tonnes; after that they get complex. Flying them requires you to adjust the throttle downward as you go.

One other thing to consider - if you want to do a staged rocket, try to have each subsequent stage up progressively add a greater fraction of the total 4550 delta-V to orbit requirement. I go with:

1 stage: 1/1 (all 4550 there)

2 stage: 1/3 in the first stage, 2/3 in the second

3 stage: 1/6 in the first stage, 1/3 in the second, 1/2 in the third

4 stage: 1/10 in the first stage, 1/5 in the second, 3/10 in the third, 2/5 in the fourth

And so on.

Also helps to consider for purposes of building boosters that the full mass of almost every liquid fuel tank in KSP (with the exception of the Oscar-B and Round-8) is exactly nine times its dry mass. When using Tsiolkovsky, you can add the "dead mass" to both the M and Md parts of the equation, and then substitute M=9Md and run it backwards. Be sure to add your engine mass and decoupler mass to the deadmass of any subsequent stages.

2) What's your launch TWR? If it's above 2.2 (i.e. the gee meter jumps up above the green area the moment you hit the space bar), throttle back - you've got too much thrust.

You might also try putting launch clamps on the booster - they've become increasingly necessary in 0.22.

And then you might also want to put your engines into the ground in the VAB; the game will automatically adjust them to ground level for the launch.

Edited November 11, 2013 by capi3101

[Kasuha]

besides some essential tools such as Kerbal Engineer, Enhanced Navball + Docking Indicator and Editor Tools

That doesn't count as playing stock. That only counts as playing with stock parts and default aerodynamics.

Question #1: The delta-v... Oh the delta-V... I just can't get stuff into orbit. I struggle so much with adjusting my rockets to stock aerodynamics etc. What are some tips to keep my rockets looking realistic but still be able to lift my payloads?

You don't see delta-v of your ship when playing stock. Do it the Kerbal way - more boosters. Or more fuel. Or stronger engines.

Question #2: I just built a 50 ton payload launcher(for my Duna lander and ascent vehicle). Now, I can just just get this thing into orbit. But I'm not enjoying my launches as I normally do with FAR and so on... They just wobble and flex so much.

A picture of the craft might help. But lifting 50 tons isn't that hard. This lifted two orange tanks (72 tons, in the middle) and didn't wobble at all:

[ANWRocketMan]

Ok, well... I fixed my launcher... Finally got it right. A little too circular for my taste...

Two things were wrong(thanks @capi3101):

#1: My ascent profile was very wrong! I started my gravity turn much too steeply and early. This because I usually start at 1-2km with Real Size and FAR.

#2: I had much too low TWR on my third stage for orbital insertion.

My first stage had a TWR of around 1.6. Third stage around 1.4(a little too low, I like to have at least around 1.8 since I'm already practically 30 degrees by the time this activates). I'll try to keep in mind what you said about the stage dV next time though. Makes sense to do it that way.

That doesn't count as playing stock. That only counts as playing with stock parts and default aerodynamics.

Sorry, I should have clarified: I consider stock as anything with stock gameplay mechanics. Considering I can and have done all those things manually anyway, it does not change the game for me. It just streamlines the experience as I don't necessarily have the time to do it all manually.

You don't see delta-v of your ship when playing stock. Do it the Kerbal way - more boosters. Or more fuel. Or stronger engines.

I can and probably would just calculate that myself anyway if I wasn't using Kerbal Engineer. So it makes little difference to me. I'm looking for the nostalgic experience but one that does not exceed my "OCD"(not really OCD, but I like knowing stuff as they are, and they must be neat). So... For most people it's a sin punishable by Kraken but for me it's just a handy tool to make the experience more pleasurable.

A picture of the craft might help. But lifting 50 tons isn't that hard. This lifted two orange tanks (72 tons, in the middle) and didn't wobble at all:

*snip*

It's not building a capable rocket that is bothering me, I just hate all this jiggling and wobbling that I'm not used to. normally(with my mods installed, NO MechJeb) I can actually enjoy doing my launches(at least with a tested launcher). But this is just a harrowing experience. The problem is I like my rockets looking at least like a half-a***d real rocket.

[Scarecrow88]

It seems to me that things are less stable in this latest patch. Rockets that used to launch without problem are now suffering joint breaks that separates the command unit from other parts of the rocket, which usually means that you can no longer control the engines, or part of your staging no longer responds. Very frustrating.

[Sirrobert]

If you enjoyd it better with FAR, than why don't you just reinstal FAR?

[Kasuha]

The problem is I like my rockets looking at least like a half-a***d real rocket.

The problem is, KSP physics, especially unmodded, is very different from real life physics. So building what you consider a nice rocket is like trying to breed a fish to have shape of a bird. You may succeed but it will probably suffer a lot of problems from the shape not suited for its environment. Fish are beautiful, too, if you don't expect them to look like birds.

I was also trying to force my KSP rockets into real-life shapes when I started playing. Since then I learned to appreciate beauty of conquering the game physics instead.

The best you can do is to fasten parts of your rockets together with struts in a way which will not break the shape. Stacked tanks can be strutted together in a way which does not stand out - just pull struts just next to the edge of one tank to just next to the edge of the other tank and it will become much less wobbly. You can find an example in the picture below where the payload is long and thin and I did not suffer any problems lifting it. Notice struts right at tank edges, lower ones are placed with 6-fold symmetry for greater strength, upper ones at 4-fold symmetry to make it easier on part count.

Another important thing is correct ascent. When getting to orbit, you need to burn as close to prograde as possible and avoid sudden turns. People in KSP often ascend to 10 km, then turn right at 45 degrees. If a real rocket did that, it'd snap in half.

[codepants]

Question #1: The delta-v... Oh the delta-V... I just can't get stuff into orbit. I struggle so much with adjusting my rockets to stock aerodynamics etc. What are some tips to keep my rockets looking realistic but still be able to lift my payloads?

Do it the Kerbal way - more boosters. Or more fuel. Or stronger engines.

Ignore Mr. MOAR here. Build small.

I mean, ultimately I think everybody's goal is to get huge stuff into space, but in my opinion the smaller the better. It took me a while to figure out that you can go to the moon and back, for instance, in only three stages, without using any of the "big" tanks or engines. The problem I suffered when getting started, and the problem I think a lot of new players suffer, is that we think the solution is more fuel and more engines. That's part if it, but it's the part with quickly diminishing returns. If you can build a small rocket, you can get into space. After you've done that 100 times, then magically, getting larger rockets into space will be easier, too.

Also, watch youtube videos of skilled players (OperationDX is my favorite, Scott Manley is also popular). Even if you don't copy their designs, you will learn from them.

Since you're using Kerbal Engineer, you might research how much dV you need and experiment with different designs that give you that amount. You will almost always find it easier to give small rockets the necessary dV than larger ones. And remember, stage-relative dV matters. If you have 100dV in your first stage and 10,000dV in your last, you probably won't get to space. The other way around will work much better.

As far as making them "look real..." it's possible... but first I recommend finding what works... then make it "look real."

Good luck!

[Kasuha]

Ignore Mr. MOAR here. Build small.

Well since the problem was that a rocket built for FAR was not strong enough to make orbit in stock aerodynamics that was a right answer. Stock atmosphere is thicker so you need bigger rocket for the same task.

My point is, I have never used any mods and my designs are still competitive. If you need external help, don't play stock. If you want to play stock, try playing it without numbers which are not in the game. So far I have found it's very possible.