hoojiwana

[1.1] AB Launchers 1.2 - 5m Energia parts [22 Apr]

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I don't have much modding experience, and so don't know where most begin when choosing initial numbers for mass, thrust, and specific impulse so if this suggestion is on the order of the glaringly obvious feel free to ignore it entirely.

I would start by looking at a reasonably well balanced mod that includes real-world components, I chose FASA, then begin comparing the real-world components using ratios of their masses, thrusts, specific impulses and the like. I compared the core stage of the Energia to the S-II, not because they are very comparable, but because the thrust of the J-2 is far closer to that of the RD-0120 than the F-1.

Doing this gave me a total empty mass of the core stage of 73.13 tons, this would include the 4xRD-0120 engines and the dry masses of all other stage components. Comparing the masses of the J-2 and RD-0120 gave a mass for the RD-0120 of about 8.2 tons leaving approximately 40.33 tons remaining to be split between the remaining core stage components (tanks, nose cones, etc). Then, using the propellant mass to empty mass ratio to determine the mass of propellants gave 705,489 kg. This is then converted to liquid fuel and oxidizer units to be 63,494 liquid fuel units and 77,604 oxidizer units. Though this keeps everything in proportion those numbers seem to be rather large especially considering that the FASA S-IC defaults to 18,000 liquid fuel and 22,000 oxidizer and the S-IC is more massive in real life than the Energia core. If I instead use the ratio of propellant mass to empty mass in the FASA S-II and apply it to the Energia numbers I get a perhaps more reasonable 31,001 units of liquid fuel and 37,890 units of oxidizer.

As for the thrust and ISP of the RD-0120 I came up with a max thrust of 1045 and vacuum ISP of 457 and a sea level ISP of 371 (this value was obtained using the ratio of the vacuum ISP to sea level ISP of the real RD-0120).

As I said, I'm by no means an expert at part balancing but maybe the above may be helpful in some way.

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Here's some testing of the 5m parts and some mock-ups of the boosters!

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Pic 1: First attempt, didn't have decoupler fix installed so separation was disastrous. The engines on the boosters in all these screenshots are using the Mainsail model but the Hurricane (RD-170) stats.

Pic 2: Separation went better with the small exception of the Sepratrons burning through my tank and engines. So the MM config that will be included may also be changing those to have no thrust damage.

Pic 3: Made a quick Vulkan to see how the engine stats fare on larger symmetrical rockets

Pic 4: Booster separation, with no thrust damage Sepratrons (makes them so much easier to use), and much nicer balance on the engines.

Pic 5: This tiny bit of fuel left over is because the engine on full throttle can't actually consume it due to rounding errors.

Many numbers and statistics.

I'm not sure on the numbers that FASA uses for tank dry mass or it's engine balancing, so I can't say how good those numbers are. Given much rough testing with the parts in game now it's looking like the RD-0120 (Cyclone in ABL) will be fairly close in stats to the Mainsail. Slightly less thrust, mass and ISP, but makes up for it in gimbal range. The difference in mass between LH2 and stock LiquidFuel is rather huge, so tank mass is much higher than you might think. Currently the 3 tanks required to closely approximate the Energia core in (relative) length is over 440 tons. All subject to change of course!

Edited by hoojiwana

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Out of interest, how do you get the asymmetrical payload to work in KSP? I've never understood how NPO Energia actually managed it in reality.

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Out of interest, how do you get the asymmetrical payload to work in KSP? I've never understood how NPO Energia actually managed it in reality.

Basically through engine gimballing in the case of the Energia.

The space-shuttle used tilted engines to offset the balance issues from asymmetry, but the Buran was much more a payload than an active part of the launch.

In the case of AB launcher parts, the case is the same:

-2bdfcaea6b.jpg

This Polyus test is a little misleading, as the Polyus is firing its engines, a bit of a staging mishap.

But, even without the thrust of the Polyus, the rocket quite easily holds steady.

It's the work of the main and radial engines to tilt about and maintain the desired direction.

In reality, I think people will be much more comfortable with the "Vulkan" or "Energia-M" style setups, as with the KSP editor, it may take a little more time to build radial payloads.

Edited by Beale

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Basically through engine gimballing in the case of the Energia.

The space-shuttle used tilted engines to offset the balance issues from asymmetry, but the Buran was much more a payload than an active part of the launch.

In the case of AB launcher parts, the case is the same:

-http://puu.sh/fvG2j/2bdfcaea6b.jpg

This Polyus test is a little misleading, as the Polyus is firing its engines, a bit of a staging mishap.

But, even without the thrust of the Polyus, the rocket quite easily holds steady.

It's the work of the main and radial engines to tilt about and maintain the desired direction.

Cool, thanks for the explanation! So it's similar to the Space Shuttle but carried out by the launch vehicle rather than the orbiter.

In reality, I think people will be much more comfortable with the "Vulkan" or "Energia-M" style setups, as with the KSP editor, it may take a little more time to build radial payloads.

Personally, I find spending hours building asymmetrical rockets and then watching them somersault out of control is one of the best ways to play KSP :D

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Love the parts, but is there an RO config available?

(I'm trying out the RO kind of thing)

Thanks,

Astrofox

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Initial impressions: these parts are big! Like, REALLY BIG!!! First time I've ever felt that the VAB was too small :D

Good job on the release, the parts look really good so far. I'll have a crack at a Vulkan rocket this evening and then post some feedback and perhaps some screenshots tomorrow.

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I take it that means things are coming along well? :)

Yep! :D

I. Love. It! So beautiful!

I'll try to see if something can be done with the balance. :)

Appreciate it.

Love the parts, but is there an RO config available?

(I'm trying out the RO kind of thing)

Thanks,

Astrofox

Not just yet, this first version is just the basic implementation of the parts, which is why there are no descriptions and the Agency config is placeholder. Once the parts have been sorted out properly, and the MM config to tweak a few other things is done, then things will be a little more stable for someone to have a crack at making a decent set of RO configs. Personally I'm interested in seeing how well a scaled up LH2/LOX Energia core works!

Initial impressions: these parts are big! Like, REALLY BIG!!! First time I've ever felt that the VAB was too small :D

Good job on the release, the parts look really good so far. I'll have a crack at a Vulkan rocket this evening and then post some feedback and perhaps some screenshots tomorrow.

Big parts for big payloads! If you want truly big rockets though have a little look at the beasts people make for RSS.

Edited by hoojiwana

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So I just played around with the beta for a bit.

Two observations :

1 - The parts seem to all work well, the only issue I ran into was the lack of smoke from the big quad, but that was mentioned on the front page. I won't speak to the "balance" of the parts, but visually and functionally everything seems good.

2 - All we need now is a 2.5m R7-sidebooster-like tank, and all will be right with the world. (I know a few other mods have them, but frankly they're terrible)

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The results from tests with a Mir-2 payload:

Performance is awesome! 25 tons payload to LKO without difficulties with 1000 m/s left.

The only problem is... the decouplers. Stock decouplers don't hold well, and the sepatrons cause the core tank to explode due to overheating. Will you make custom high-power (and possibly solid-fueled like SpaceY) decouplers?

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I had good luck with stock decouplers + struts, YMMV

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The beta's going great!

http://i.imgur.com/0hDFJfI.png

That's basically how my own testing went!

Looking at this picture in the OP:

http://i.imgur.com/kkhiH8K.png

What a Korolev Mess...

Neat isn't it? Surprised me how well that works with just 2 Sepratrons per stack and the largest radial decoupler (more on this below).

So I just played around with the beta for a bit.

Two observations :

1 - The parts seem to all work well, the only issue I ran into was the lack of smoke from the big quad, but that was mentioned on the front page. I won't speak to the "balance" of the parts, but visually and functionally everything seems good.

2 - All we need now is a 2.5m R7-sidebooster-like tank, and all will be right with the world. (I know a few other mods have them, but frankly they're terrible)

Thanks for trying things out. On number 1, the smoke from the Cyclone cluster is partially fixable, but there will be only a single smoke source that doesn't gimbal and is almost certainly too small compared to the diameter of the part. There's a stock bug with the way the game spawns smoke FX, so it's a little out of my control. On number 2, a slanted tank type thing isn't really on the cards right now, but IIRC KW Rocketry does have that part if you wanted it.

The results from tests with a Mir-2 payload:

Performance is awesome! 25 tons payload to LKO without difficulties with 1000 m/s left.

The only problem is... the decouplers. Stock decouplers don't hold well, and the sepatrons cause the core tank to explode due to overheating. Will you make custom high-power (and possibly solid-fueled like SpaceY) decouplers?

I had good luck with stock decouplers + struts, YMMV

Got any pics of your Mir-2 Launch? I want to see how ridiculous it looks! :P In my testing the hydraulic decoupler and two or three struts was just fine for holding the 2.5m boosters to the 5m core, as well as decoupling them. If you're not already, I strongly recommend using the bugfix plugins, helps immensely with the decouplers. For the Sepratrons, the intention is to include an MM config to switch the stock Sepratron to have no thrust exhaust damage, so you can angle them towards your core tank without them exploding it. I've been using a straight up config edit in testing (which I don't recommend) and it has made building so much easier, really hoping a change like this makes it into 1.0.

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The lack of smoke on the large cluster engine doesn't really bother me at all, I can't speak for others.

Not all rocket thrusters are as "smokey" as others. A little variety in-game adds to the flavor, IMO, especially where the exhaust looks more blue compared to most other engines.

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Got any pics of your Mir-2 Launch? I want to see how ridiculous it looks! :P In my testing the hydraulic decoupler and two or three struts was just fine for holding the 2.5m boosters to the 5m core, as well as decoupling them. If you're not already, I strongly recommend using the bugfix plugins, helps immensely with the decouplers. For the Sepratrons, the intention is to include an MM config to switch the stock Sepratron to have no thrust exhaust damage, so you can angle them towards your core tank without them exploding it. I've been using a straight up config edit in testing (which I don't recommend) and it has made building so much easier, really hoping a change like this makes it into 1.0.

I don't find it ridiculous, it's just huge. :)

I3qMvMDGjEo.jpg

8U3kUrJt2zw.jpg

fcMSpui8y1E.jpg

35a_MIR2.jpg

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Having played around with the parts for a few hours, this is the best Vulkan-style launcher I've come up with yet. I have no idea what the payload capacity is, but I'd estimate it at "quite a lot".

http://imgur.com/a/GdxsX#0

I've had less luck with Buran-style launchers, the damn things keep tipping over! I'm going to keep at it though, the problem is with my designs rather than the mod.

One possible issue I noticed is that the slanted nosecones for the boosters don't seem to work. The data files suggest that they should have a Separatron built into them but nothing shows up or gets activated in the VAB or in flight. Has this function not been implemented yet, or is it a bug?

Edited by Tapejara

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Having played around with the parts for a few hours, this is the best Vulkan-style launcher I've come up with yet. I have no idea what the payload capacity is, but I'd estimate it at "quite a lot".

http://imgur.com/a/GdxsX#0

I've had less luck with Buran-style launchers, the damn things keep tipping over! I'm going to keep at it though, the problem is with my designs rather than the mod.

One possible issue I noticed is that the slanted nosecones for the boosters don't seem to work. The data files suggest that they should have a Separatron built into them but nothing shows up or gets activated in the VAB or in flight. Has this function not been implemented yet, or is it a bug?

Hiya! Nice Vulkan!

The Nose cones were supposed to have separatrons, hence the code leftover. However, the end result was a bit pointless, it did not provide much advantage over a regular decoupling.

So, yup, I'm aware of that, it will be fixed :)

Buran style launches are possible (Without igniting the shuttle's engines). But it is a little tricky to balance it.

If you don't mind taking a little historical inaccuracy, crossfeed the core fuel tank to a Buran orbiter, with engines ignited during ascent, it makes the whole thing quite easy to do.

Sadly I have no pics of a shuttle, but here's a Salyut ascent using the same deal.

5308c0a62c.jpg

The lack of smoke on the large cluster engine doesn't really bother me at all, I can't speak for others.

Not all rocket thrusters are as "smokey" as others. A little variety in-game adds to the flavor, IMO, especially where the exhaust looks more blue compared to most other engines.

It is Hydrolox! (Or it is supposed to imitate Hydrolox)

So, not as smokey as some other types of fuel.

868dd51e6b.jpg1f259f55b1.jpg

Wow!

I don't think you will mind if I immediately plagiarize this and do it in my own game? :D

Edited by Beale

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Thanks all for giving things a go and returning feedback to us, it's been a big help! One of the things you guys have noticed is the fact there's always left over dV, so the engines are going to get increased mass and thrust and reduced ISP to hopefully burn through all that LFO in the big tanks. For Vulkans and similar huge lifters there's also going to be this upper stage engine cluster:

et0Ipvq.jpg

The lack of smoke on the large cluster engine doesn't really bother me at all, I can't speak for others.

Not all rocket thrusters are as "smokey" as others. A little variety in-game adds to the flavor, IMO, especially where the exhaust looks more blue compared to most other engines.

It's not a big problem, especially with the radial boosters that do make smoke. Should the Hurricane be making more smoke or is it about right?

I don't find it ridiculous, it's just huge. :)

I'm not entirely sure what I was expecting! Does look really cool though.

Having played around with the parts for a few hours, this is the best Vulkan-style launcher I've come up with yet. I have no idea what the payload capacity is, but I'd estimate it at "quite a lot".

Wow that KVV picture is pretty big! How well does your booster separation usually go? Are you using the decoupler fix plugin?

I've had less luck with Buran-style launchers, the damn things keep tipping over! I'm going to keep at it though, the problem is with my designs rather than the mod.

Try transferring fuel in the 5m core up away from the engines and keeping the nose tank topped up if possible. Helps a lot with stability, and nose-heavy is even how the real Energia was balanced since the LOX tank (~600 tons) is in the nose, while the rest of the tank is a mere ~100 tons of LH2.

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Buran style launches are possible (Without igniting the shuttle's engines). But it is a little tricky to balance it.

If you don't mind taking a little historical inaccuracy, crossfeed the core fuel tank to a Buran orbiter, with engines ignited during ascent, it makes the whole thing quite easy to do.

Wow that KVV picture is pretty big! How well does your booster separation usually go? Are you using the decoupler fix plugin?

Try transferring fuel in the 5m core up away from the engines and keeping the nose tank topped up if possible. Helps a lot with stability' date=' and nose-heavy is even how the real Energia was balanced since the LOX tank (~600 tons) is in the nose, while the rest of the tank is a mere ~100 tons of LH2.[/quote']

Thanks for all the advice, with further testing- and, admittedly, shrinking my payload a bit- I have launched a mini-Buran!

KX0khVw.png?1

Quite a delicate balancing act, but as with most things in KSP the effort was worth it. Even with the lowest fuel tank empty at launch, that shuttle is now on its way to Minmus :D

EDIT: The decouplers were a nightmare without the bug fix, though now I've installed it they work fine without any Separatrons.

Edited by Tapejara

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