[0.20.2] Zenith rocket family (modernised for 0.20.x with perfect subassembly)

[Temstar]

Some time ago in 0.19.x days I made the Zenith rocket family and it was good. But time has moved on since then and with 0.20.2 now out with the new Skipper engine I thought I'll do an upgrade to the line up.

The common features of the Zenith rocket family remain the same:

• >15% payload fraction
  
• asparagus staging with reliable staging sequence
  
• clustered engine core for sustained high Isp
  
• RCS system for on orbit attitude control, in case payload has low maxRot
  
• probe core and electrical system (including small solar panels) for space loitering and self-deorbiting
  

So what are the upgrades?

• Supernova SHLLV now officially added and recognised as part of the Zenith family, bringing the max lift capacity to 160 tons
  
• Skipper engine replacing some of the cluster engines on Zenith V, VII and IX, resulting in dramatic part count decrease for a small decrease in payload fraction
  
• No more hiding parts in the decoupler - I find that many payload often need to take advantage of that space in the decoupler, so that space have been cleared out for payload use
  
• Sepratron placement optimised - now all Zenith rockets have powered separation including Zenith II
  
• other minor improvements mostly to optimise part count. Notably Zenith IX and Nova's double cluster now constructed with a new, better method
  
• perfected subassembly files, no more missing struts or fuel lines. See the second post for more details
  

So as with before, the common shared design of the Zenith family results in a similar ascent profile:

1. If you are launching a Zenith rocket with big gimbling booster engines (ie, Zenith V, Zenith VII, Zenith IX, Nova and Supernova), double tap 0 to lock gimbal. Then turn on ASAS, throttle up to max and lift off.

2. Ascend directly up and stage asparagus pairs once they run out of fuel. If you fly with either the proofing payload included in the original .craft files or ones with similar mass then all but one pair of booster should run out just after 10k altitude (that's two pairs jettisoned for all except Zenith III, which will lose it's 3rd pair of boosters at 10k). Once you're down on your last pair of asparagus booster pitch down slowly to 45 degrees for gravity turn.

3. By the time your last pair of boosters run out you should be nearly horizontal. Use the core stage to continue to build your orbital velocity.

4. Upon reaching stable orbit. Decouple the rocket from the payload, use [] to change control to rocket, flip it around with RCS and perform an deorbit burn with the remaining fuel to ensure no space junk. All Zenith rockets have been tested to have enough fuel for deorbit burn while using the proofing payload.

How to put payload onto of a Zenith rocket:

The best way is to install Subassembly Saver/Loader. Once you're done follow these steps:

1. First you have to figure out how heavy of a payload you have:

Here we have a giant spacecraft designed to house 134 kerbals in orbit. At a hair over 110 tons we can see from our table of rockets at the top that this is just under the maximum payload of Nova.

2. So open up your subassembly loader, find the Nova subassembly

3. Hit load and you'll have the Nova booster under your mouse, So simply attach it under your payload. As with other parts in KSP sometimes the parts won't attach properly in one go, so just attach it to somewhere else, pick it up again and place it where you want it to go.

There, 4627m/s coming out of Nova to send our spacecraft to orbit. Adding three struts between our unwieldy payload and Nova to stiffen up the connection and we have the craft I flew successful above.

But wait Temstar! you say, you didn't explain how to actually get those subassembly installed into Subassembly Saver/Load for loading up under payloads. Aww see here is something different from 0.19, while upgrading the Zenith rockets I've discovered a major breakthrough to how to use Subassembly Saver/Load which overcomes an old problem with struts and fuel lines. For exactly how that's done you'll just have to read on.

Craft files:

Zenith rocket family - http://www./download/3xteo1dm7j5okba/Zenith2.rar

Zenith subassemblies - http://www./download/9wmk6o78o4hcnge/Zenith2_subassembly.rar

Edited June 1, 2013 by Temstar

[Temstar]

Perfect Subassembly

After posting the original set of Zenith rockets, by far the most common negative feedback I got was "your rocket doesn't work properly! I run out of fuel way before reaching orbit and the rocket was pretty wobbly". 90% of the time I don't need to ask for a screenshot or more information, I simply tell them "check the fuel lines and struts against the proofing payload copy, you'll missing some due to Subassembly Saver/Loader".

If you've played with Subassembly Saver/Load you will know what I'm talking about. One of the big bugs holding this amazing tool back is its inability accurately render struts and fuel lines. You take off the booster section of a Zenith rocket, save it as a subassembly and then load it up under an payload and chances are you'll get this:

See that, the fuel lines are all messed up. To get the rocket to work properly they will have to be recreated. And while that's fairly easy for me since I know the ins and outs of my rockets like the back of my hand I can imagine this is a mighty annoying task for someone who's using a Zenith for the first time. So for the modernisation I decided to tackle this issue.

I've heard that this issue was due to the order the parts are rendered in - if the destination of the strut/fuel lines are not yet rendered by the game's engine due to the order they appear in in the subassembly file then the part goes missing. So the first thing I tried was opening up those .craft files in the subassembly folder and try to manually edit the file and put all the struts and fuel lines at the bottom. Save and load up the subassembly - no dice, still missing fuel lines. But from scrolling through that craft file I can see what the problem is. See when you save a subassembly you create a .craft file, only it doesn't resemble the original .craft file generated by KSP at all - it's all in some messed up order. No wonder when you then load up that subassembly some stuff goes missing

But while I have the .craft file open, I noticed something:

"Hmmmm, looks like this thing has the decoupler as the root part, that looks kind of like a KSP 0.20 .craft file now that we can have almost any part as a root part."

And then the apple falls from the tree, the bathtub overflows and I had a moment of epiphany:

A subassembly .craft file is not just like a KSP 0.20 craft file, a subassembly .craft file IS a KSP 0.20 craft file

So if a subassembly is a 0.20 craft file, except with all the parts in messed up order, wouldn't that mean a KSP 0.20 craft file, generated by KSP and able to be correctly loaded by KSP is actually a subassembly with the parts in the correct order?

To the Vehicle Assembly building!

So we start off with Zenith VII

We remove the proofing payload and use the new "delete root part" trick to make a new decoupler root part and fit it to the rocket and save the craft.

Copy the .craft file from save folder into the subassembly folder under lifters

Start a new craft and upload up Zenith VII that we've just saved

Hallelujah! It works!

So there you have it. To have the perfect Zenith rocket subassemblies just download that subassembly file, extract all the .craft files to your:

KSP\GameData\subassemblyLoader\subassemblies\Lifters

Folder and there you have it. All Zenith rockets as perfect subassemblies. No more dealing with missing struts and fuel lines.

Edited June 1, 2013 by Temstar

[bulletrhli]

Yes! Welcome back Temstar! Really love this! Been a follower for a long time and here we are, everything up to date and beautiful. Glad you figured out that Subassembly follows the rules of the current release of KSP. Makes everything much easier and technically we don't really need it anymore, you can just save the lifter and boom, that is it.

Glad you added the SuperNova to the Zenith rocket pack, makes it a lot easier and everything is all together now and it makes me a happy panda.

[zekes]

Really high quality stuff man!

[allockse]

This is excellent, been waiting on this post. The craft file information is interesting, I didn't know the order of the parts affected struts/fuel lines, but it makes sense thinking about it. I wanted all my builds organized in SubAssembly when I installed the 0.19 Zenith pack so I unintentionally avoided the bug in the first place. These things have been working perfectly out of the box for me, I can't wait to work with these new models.

Edited June 1, 2013 by allockse

[TheWanderer]

nice work as always

[allockse]

Temstar, quick question for you. Do you know of a way to preserve staging of symmetrical objects when repositioning them?

I've added some radial parachutes to the asparagus and core stage, but when I adjust the position I have to completely redo the staging. Gets extremely frustrating after about 10 tests.

While this specifically has nothing to do with the performance of your lifters, I figure you might know. Thanks in advance.

[sgt_flyer]

very nice rocket pack as always, plus the additional subassembly .craft files already prepared is a really nice touch

[Shuttle]

I'll try out your rockets, they look awesome. I am planning to post my own rocket family so your subassembly fix was very useful! Do you test you rockets with low fps?

[Commander Zoom]

After getting to the Mun and Minmus with my own designs, I've switched over to using the Zenith family exclusively for all of my manned launches. The components of my space station went up on Zenith IIIs and Vs, and so will the pieces of my interplanetary ships. The quality of your work speaks for itself, and it just keeps on getting better.

[csiler2]

Your rocket designs are so amazing it makes me want to throw my hands up in disgust

Out of curiousity, do you find that adding the smallest rockomax tank to your boosters on the Nova improve their performance by allowing 100% thrust? I tried it on a single stack design, but found that the joint was too unstable. Instead I took the 10% cut in thrust so that I could have two orange tanks of fuel.

Also, I'm curious about how you approach your design process. Do you start at the top or the bottom of the rocket?

[Execute13]

Good to see the rockets updated. How much of a difference does the new clustering system make to the part count of Nova?

[Temstar]

Good to see the rockets updated. How much of a difference does the new clustering system make to the part count of Nova?

Nova's part count went down by 30 from 256 to 226 due to both new clustering method as well as better Sepratron placement allowing me to halve the number of Sepratrons.

Zenith V, VII and IX benefited from Skipper and the part count decreases are pretty dramatic:

Zenith V: 159 -> 115

Zenith VII: 208 -> 168

Zenith IX: 256 -> 212

[Execute13]

That is very impressive! Also, is there any way to stop the rockets from spontaneously exploding on the launchpad after a certain amount of time or is that just an intrinsic property of large-scale Kerbal engineering?

[Temstar]

That is very impressive! Also, is there any way to stop the rockets from spontaneously exploding on the launchpad after a certain amount of time or is that just an intrinsic property of large-scale Kerbal engineering?

Does that refer to one of the Zenith rockets specifically or rockets in general? I did test how well these rockets stand on the pad and it seems like all of them at least with the proofing payload should be able to stand by themselves on the pad indefinitely.

Anyway the trick is you got to get as many engines as possible on the bottom flat so that the weight of the rocket is spread out across all the engines. If you have 18 engines and the weight only sits on 4 out of the 18 engines then chances are it will eventually fall over.

Worse comes to worst use the launch clamps and lower the rocket so that at least some of the rocket engines are stuck through the floor of the VAB. When you do that those part of the rocket will be sitting flat on the pad and the rocket will have the launch clamps also supporting it.

Out of curiousity, do you find that adding the smallest rockomax tank to your boosters on the Nova improve their performance by allowing 100% thrust? I tried it on a single stack design, but found that the joint was too unstable. Instead I took the 10% cut in thrust so that I could have two orange tanks of fuel.

You're always going to get joints anyway, so it's a question of TWR and how to stitch tanks together. If you want exactly two orange tank of fuel and still allow 100% thrust you can always use the Supernova method and stack 3200L tank, 6400L tank and then another 3200L tank on top of a mainsail.

Edited June 2, 2013 by Temstar

[Execute13]

I was having trouble mostly with the Nova, both with the proofing payload and a lighter one. The rocket would continually wobble more and more until one or more of the boosters dislodged and blew up the rocket. It only takes around 10 seconds or so for me.

Edited June 2, 2013 by Execute13

[Temstar]

Hmm, I put Nova on the pad and went away to do something else. 9 minutes later I came back and found the payload have snapped off the rocket, however the rocket itself is standing sound.

[Execute13]

Hmm, I put Nova on the pad and went away to do something else. 9 minutes later I came back and found the payload have snapped off the rocket, however the rocket itself is standing sound.

Hm. It may be due to my computer having trouble running the ship. I'm on a pretty terrible laptop, so the physics might be a bit too jittery.

[Spanier]

Are you going to fill the gaps in the naming convention?

So will there be a Zenith I, VI and VIII (considering "Nova" as "Zenith X")

[Temstar]

The number refer to the number of LV-T30 / LV-T45 engines on the centre core. So Zenith II has two LV-T45 for its core, Zenith V has one LV-T45 and four LV-T30 fore its core and Zenith IX has three LV-T45 and six LV-T30. By that naming convention Nova would be Zenith XII and Supernova wouldn't fit since it uses three Mainsail for its core.

Zenith I would be too simple of a design to include. Zenith VI and Zenith VIII will have awkward number of engines for their core (Zenith VI would be VII minus the centre engine, VIII would be a 2+6 double cluster).

[Execute13]

Another thing, I've noticed that Zenith V is actually better than Zenith IV in every way except payload fraction. Is Zenith IV in need of renovation, or is it just a consequence of the Skipper engines?

[Temstar]

Another thing, I've noticed that Zenith V is actually better than Zenith IV in every way except payload fraction. Is Zenith IV in need of renovation, or is it just a consequence of the Skipper engines?

Oh you're looking at the cost. Yes it's a Skipper thing. Currently engine costs are pretty arbitrary so the cost of rocket and cost per ton to LKO numbers are of academic interest only. Currently a LV-T30, Skipper and Mainsail all cost $850 which is clearly absurd considering their vast differences in size. If those engine cost numbers were true you're pretty much always better off cost-wise building "big dumb boosters" purely out of mainsail to lift payloads.

[wasmic]

Dammit! I just thought I had found my dream rocket... but no, the payload capability is too small. I want to send a fuel tank weighing in at 190 tons into orbit, but how am I supposed to do that??? MOAR BOOSTERS?

Nice rockets, by the way. I like your designs.

[Shuttle]

Dammit! I just thought I had found my dream rocket... but no, the payload capability is too small. I want to send a fuel tank weighing in at 190 tons into orbit, but how am I supposed to do that??? MOAR BOOSTERS?

Nice rockets, by the way. I like your designs.

Could you, please, post a download link to the fuel tank? I've almost finished working on my 200t-rocket so it would be great to test it

[Temstar]

Dammit! I just thought I had found my dream rocket... but no, the payload capability is too small. I want to send a fuel tank weighing in at 190 tons into orbit, but how am I supposed to do that??? MOAR BOOSTERS?

Nice rockets, by the way. I like your designs.

If you don't have any luck with a 190 ton lifter you could always put a fuel line in between your payload and a Supernova. The rocket will just burn through some of the payload fuel for that extra bit of delta-V. You will end up with a payload more than 160 tons but less than 190 tons in orbit. Once in orbit transfer almost all the fuel out of Supernova back into the payload leaving just a hair for deorbit burn.

Might want to add some SRBs too in case TWR at lift off goes too low.