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

[elanachan]

Hi there, another user. I just wanted to mention that I had attempted to launch a payload weighing in at 44.89 tons and the VII failed to lift it into an orbit of 100m despite being rated for 62.47 tons. After attaching the payload and enough spacetape to keep it from wobbling around during launch I was unable to escape kerbin's atmosphere with my top speed never reaching 2000m/s. I am trying again with the IX with the hopes that it will do what the VII could not.

Edit: I just made an attempt with the IX, same payload, maximum reached altitude at 55.89Km with a top speed during decent bellow 1500. I don't understand why these launchers aren't preforming to specs. I would think the IX would easily be able to handle a payload almost half the weight of what it's designed for.

Edited September 5, 2013 by elanachan

[Temstar]

Hi there, another user. I just wanted to mention that I had attempted to launch a payload weighing in at 44.89 tons and the VII failed to lift it into an orbit of 100m despite being rated for 62.47 tons. After attaching the payload and enough spacetape to keep it from wobbling around during launch I was unable to escape kerbin's atmosphere with my top speed never reaching 2000m/s. I am trying again with the IX with the hopes that it will do what the VII could not.

Edit: I just made an attempt with the IX, same payload, maximum reached altitude at 55.89Km with a top speed during decent bellow 1500. I don't understand why these launchers aren't preforming to specs. I would think the IX would easily be able to handle a payload almost half the weight of what it's designed for.

You're not trying to use the versions with the proofing payload to lift your own payload are you? The root part of the booster when you load it as a subassembly should be a 2.5m decoupler. If it's anything else it mostly means you have the proof payload still loaded on top.

The subassembly versions work with the Subassembly Manager, I tested them and they load fine. I'm still using these as of 0.21.

[TMS]

Are you likely to revisit these when the stock subassembly manager is released in 0.22?

[Moencino]

After reading about your booster designs, I gave them a try. Aesthetically they're awesome, and I love the clustered centre booster. Just looks awesome. My problem is that I can't get them into orbit. Has something changed in the game since these were released such that the stock craft can no longer get to orbit? I run out of fuel every time. So far I've tried the Nova and Zenith Vll, neither of which could I get into a stable orbit. I'm wondering if I'm doing something wrong?

Asparagus staging is something I've become very familiar with, so that's not the problem. I'm launching with the stock payload - only thing I'm adding is the Engineering mod so I can track stats during launch. I separate the 2nd pair of boosters just after 10k, do my gravity turn and hold it at 45 degrees until I get the apoapsis to 75k, then I burn prograde until I run out of gas - I never even get close to getting the periapsis wrapped around the back of Kerbin. I'm assuming we're not expected to transfer fuel from the payload to complete the burn.

Any thoughts? I'd love to make these great looking boosters work. Thanks for the effort made in building and sharing them!

[Temstar]

I can't seem to replicate the issue:

Zenith VII:

Nova:

Both KER delta-V read out and experimental evidence point to them working as well in 0.21.1 as they did in 0.20.2

[capi3101]

Are you performing your testing with just your dummy payloads, or are you attaching subassemblies to different payloads, Temstar? I've had issues with the subassemblies in 0.21; my Barn Burner Heavy 7s, which worked great in 0.20 on top of a Nova, stopped working with 0.21 (the fuel lines got jacked up somehow).

Been a while since I've tried; lemme try again, see if it fails and post pics.

[sgt_flyer]

Fuel lines and struts have a nasty habit of being munched by subassemblies mods - because they don't save the parts in the correct order, so when your assembly is loaded, the fuel lines can be loaded before their target - and so won't connect.

One way to do it was found by temstar himself, and very easy to do now is to save your craft as a perfect subassembly.

Basically, you build the parts you want to turn into a subassembly in the vab or the sph, starting from the payload's decoupler, in case of wanting to turn a launch vehicle into a subassembly. Once you finished building it, name the craft and save it with the game save system, then alt-tab to windows, copy the .craft file into your save's ship folder, and paste it into your subassemblies directory.

This way, when you load this 'perfect' subassembly afterwards, the parts will be loaded in the correct order, and the struts and fuel lines should not get munched.

[Temstar]

It's working fine for me for real payloads too:

Payload mass 41.91 tons, Zenith V's maximum payload mass to LKO is 43.13 tons

Delta-V with booster:

Payload in orbit:

With subassembly I'm told that Subassembly Manager has the exact same problem saving subassemblies as the old Subassembly Loader, so yes save manually and copy your craft over.

Edited September 7, 2013 by Temstar

[Moencino]

I can't seem to replicate the issue:

Thanks for the detailed flight profile, Temstar. Ok, well this is a good thing, because clearly I can learn something about flying a better launch. Can you please tell me what I'm doing wrong? Here's my flight plan:

Launch Prep: Full power, SAS engaged.

Launch

2900m - 1st pair booster separation

10.8k - 2nd pair booster separation and roll to 45 degree angle facing 270 degrees. Hold that course and monitor Ap as it climbs toward 75k

31.3k - 3rd pair booster separation. Still holding 45 degree angle at 270 degrees. Ap now 39.7k.

Ap 75k - cut power, rotate to prograde, drift until about 30 seconds from Ap intercept then bring back to full power. Burn time remaining in S1, 46 seconds.

Fuel exhausted in S1 with Ap at 76k and Pe at -519k

I'm assuming I'm doing something terribly wrong with where I'm burning. Could I get some input please? Much appreciated!

[Elmetian]

10.8k - 2nd pair booster separation and roll to 45 degree angle facing 270 degrees

Are you trying to put it into a retrograde orbit? If not, then you need to be burning towards the 90° marker. You'll need more ÃŽâ€v to get into a retrograde orbit because you have to negate the velocity imparted by Kerbin's rotation.

Edited September 7, 2013 by Narcosis

[Temstar]

Thanks for the detailed flight profile, Temstar. Ok, well this is a good thing, because clearly I can learn something about flying a better launch. Can you please tell me what I'm doing wrong? Here's my flight plan:

Launch Prep: Full power, SAS engaged.

Launch

2900m - 1st pair booster separation

10.8k - 2nd pair booster separation and roll to 45 degree angle facing 270 degrees. Hold that course and monitor Ap as it climbs toward 75k

31.3k - 3rd pair booster separation. Still holding 45 degree angle at 270 degrees. Ap now 39.7k.

Ap 75k - cut power, rotate to prograde, drift until about 30 seconds from Ap intercept then bring back to full power. Burn time remaining in S1, 46 seconds.

Fuel exhausted in S1 with Ap at 76k and Pe at -519k

I'm assuming I'm doing something terribly wrong with where I'm burning. Could I get some input please? Much appreciated!

Your flight plan doesn't seem that far off so I'm still thinking it may be a technical issue. Anyway the way I fly it:

1. Go straight up until 10km. Usually this is around 2nd pair of booster separation, though lately I've been sending lighter than specified payloads to the Mun using the core stage as the TMI stage, in which case the 2nd pair will still be attached when I start the gravity turn at 10k. Turn your heading to 45 degrees

2. At 30km ap, dip down to 30 degrees

3. At 40km ap, dip down to 20 degrees

4. At 50km ap, dip down to 10 degrees

5. At 60km ap, go down to horizontal and burn until 74.5k ap

6. Circularise at 75k orbit

A curve like this is a bit more efficient than having only two turning points, but I'm not sure if it's sufficient to explain that much of a difference.

PS: if you're doing retrograde orbit then you need to reduce payload, going retrograde incurs a 350m/s delta-V penalty compared to prograde.

Edited September 7, 2013 by Temstar

[Moencino]

Are you trying to put it into a retrograde orbit? If not, then you need to be burning towards the 90° marker.

The heading was really arbitrary - I'm just studying the benefits of this particular booster style compared to what I've built myself thus far. Since I'm planning a Duna expedition, I've taken to Westerly departures.

[Moencino]

A curve like this is a bit more efficient than having only two turning points, but I'm not sure if it's sufficient to explain that much of a difference.

Again, thanks for the detail, Temstar. I'll go try it right now.

[Elmetian]

The heading was really arbitrary - I'm just studying the benefits of this particular booster style compared to what I've built myself thus far. Since I'm planning a Duna expedition, I've taken to Westerly departures.

I think you're making a common mistake. It's a lot less efficient to put the rocket into a retrograde orbit by flying west, and you're probably wasting a lot of delta v. You should put it into a prograde orbit by flying east, then time your departure burn to sling you off in the correct direction. Use this calculator to find the correct ejection angle.

Edited September 7, 2013 by Narcosis

[Moencino]

PS: if you're doing retrograde orbit then you need to reduce payload, going retrograde incurs a 350m/s delta-V penalty compared to prograde.

DOH! I totally missed that part of your post! That must be the problem! I just flew your exact profile as described and still couldn't make it work. I think you've figured out why. Thanks! Off to confirm...

[Moencino]

I think you're making a common mistake. It's a lot less efficient to put the rocket into a retrograde orbit by flying west, and you're wasting several km/s of delta v. You should put it into a prograde orbit by fling east, then time your departure burn to sling you off in the correct direction. Use this calculator to find the correct ejection angle.

You're totally right, Narcosis! I'm glad you two figured out my screw-up...I was wondering what the hell I was doing so wrong that I couldn't get it into orbit. This also explains why getting the various chunks of my Duna expedition into Kerbin orbit required far bigger boosters than seemed to make sense based on my Mun expeditions. Total facepalm moment. I love how much there is to learn in this game about real life considerations for space flight.

[Elmetian]

You're totally right, Narcosis! I'm glad you two figured out my screw-up...I was wondering what the hell I was doing so wrong that I couldn't get it into orbit. This also explains why getting the various chunks of my Duna expedition into Kerbin orbit required far bigger boosters than seemed to make sense based on my Mun expeditions. Total facepalm moment. I love how much there is to learn in this game about real life considerations for space flight.

No worries. For what it's worth, I was doing the exact same thing for a short time back in 0.16. I tried replicating what someone did in a youtube vid without actually thinking about it... ended up attempting to reach Eve from a retrograde orbit around Kerbin. So much for having a physics degree

[Wayfare]

DOH! I totally missed that part of your post! That must be the problem! I just flew your exact profile as described and still couldn't make it work. I think you've figured out why. Thanks! Off to confirm...

Apart from some very specific rendezvous situations, there is never a good reason to launch retrograde. As said though, it's a common mistake to make and there is a persistent amount of disinformation out there on the interwebs so I don't blame you.

I'll let this old gem speak for itself:

[Moencino]

Thanks again to you both. Thus far I've only been to the Mun, and have spent the last couple weeks building and testing a base, lander, and refueling/utility rover for a Duna mission. One guide I read suggested sending more than one ship at a time to take advantage of a given launch window. So I'm sending 3. Might send a fuel barge as well, not sure. Anyway, the guides to Duna I've read suggest starting from a retrograde Kerbin orbit. Is that just bad advice?

[DerekL1963]

Thanks again to you both. Thus far I've only been to the Mun, and have spent the last couple weeks building and testing a base, lander, and refueling/utility rover for a Duna mission. One guide I read suggested sending more than one ship at a time to take advantage of a given launch window. So I'm sending 3. Might send a fuel barge as well, not sure. Anyway, the guides to Duna I've read suggest starting from a retrograde Kerbin orbit. Is that just bad advice?

It's going astray from the purpose of this thread - but I'd recommend Kerbal Alarm Clock to keep track of when mid course corrections are due, when they encounter Duna, etc... Saves a lot of jumping back and forth.

[Moencino]

It's going astray from the purpose of this thread - but I'd recommend Kerbal Alarm Clock to keep track of when mid course corrections are due, when they encounter Duna, etc... Saves a lot of jumping back and forth.

I'll check it out, thanks Derek.

I'm still hoping for input on the whole retrograde orbit if going to Duna thing. Is that a bad suggestion, and should I launch to the East as usual before heading to Duna? Any input is appreciated, as I'm just going off 'flying to Duna' guides I've found online.

[Temstar]

I'm still hoping for input on the whole retrograde orbit if going to Duna thing. Is that a bad suggestion, and should I launch to the East as usual before heading to Duna? Any input is appreciated, as I'm just going off 'flying to Duna' guides I've found online.

Yes it's a bad suggestion. When the ejection/phase angle calculator first came out there wasn't logic in place for going to inferior planets with prograde launches so the calculator always tells people to launch retrograde. There was a bit of an uproar that caused that logic to be put in. But the damage was done.

[DerekL1963]

Just mentioning for grins since Duna is the topic de jour at the moment; I'm developing a Duna exploration system, and the next thing I needed is an orbit tank farm to refuel my re-useable tug. So, I'm flipping back and forth between the game (looking at tank capacities and weights) and the JPEG listing of the Zenith family.... when it hits me that the Supernova proof mass pretty much *is* an orbital tank farm. A little time in the VAB modifying it and refining the design, and voila! a tank farm.

Temstar comes through again!

[opensesame11]

Are the subassemblies 0.22 compatible? I think that the game's new subassembly system might be slightly different.

[Temstar]

Are the subassemblies 0.22 compatible? I think that the game's new subassembly system might be slightly different.

Maybe maybe not. I kind of have difficulty imagining how Squad would do subassembly in a way that's radically different to how mods do it. But I suppose at the minimum file structures and that sort of thing will be different so I'll do a new guide.

Subassembly aside, I did consider updating these rockets. The main update I'm thinking is to get rid of all the RCS systems on the boosters and replace them with reaction wheels for control and a pair of R24-77 pointed retrograde as deorbit engines. In fact I've already got a Nova with this new setup. The lift performance is a tiny bit better but most of the benefit is in the fact that it uses something like 30 less parts. I'm still wondering if that's a worthwhile change though.

Does anyone actually ever use the RCS systems on these boosters for translation? Now that we can steer with reaction wheel we don't need steering authority from RCS any more. And with a pair of R24-77 for deorbit you can translate retrograde fine too. So really the only thing that'll be missing from the new build is the ability to translate forwards and sideways. But the only use I can think of for that is if you're actually attempting to dock a payload to something with the booster still attached.