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HeliosPh0enix

Engine Clusters in Upper Stages

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When I make engine clusters for the sake of a higher TWR, I usually don't use the built-in adapters.  Usually, I will take a radially-attachable nosecone and put it on 3-4x symmetry, then put the engines on the bottom.  I then use the displacement tool to push them together in the center to look like and engine cluster.  I do this for three reasons: 1) I think the partially visible nosecone looks better than the adapters 2) the nosecones don't make it less aerodynamic (as far as I know) and 3) I can't figure out a way to attach anything below the adapters (like if it were an upper stage and I need a decoupler below, I would have to now have several stacks of fuel tanks because of the inability to put a decoupler in the middle), and the above mentioned method leaves the node on the bottom of the fuel tank stack open.  I usually place a girder or two on this node until they just stick out below my engines, then put a decoupler on the end of that.  This way I can have a central stack below this for a lower stage.  The issue with this is that it is unshrouded and the two sections of rocket are joined by a thin girder.  Does anyone have a more effective way of doing this that still looks okay, or is this the best possible solution?  Thanks for any input.

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I just put a fairing right below the central structural part. If the engines are within the diameter of the upper stage, it works great, and looks good enough.

Edited by The Aziz

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As  The Aziz insisted  a fairing and  added separator on the upperstage tank. You can inclose the engines on the way up and have the ability to stage. You have only to be sure not to clip the engines in the understage and to surface close the fairing on the upperstage.

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+1 to @The Aziz's solution.

Decoupler to the engine in the center or to the tank above the cluster if there is no engine in a good position, interstage fairing under that decoupler.

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On 11/14/2017 at 12:47 AM, HeliosPh0enix said:

Does anyone have a more effective way of doing this that still looks okay, or is this the best possible solution?  Thanks for any input.

There are a number of options.  As already mentioned, you can hide the ugly skinny neck with a fairing.

If you use the stock multi-adapters on the upper stage, you can just have multiple stacks in the lower stages.  Just be sure to strut them together.

My favorite alternative, however, is to use mod adapters / thrust plates.  These parts are the diameter of the upper stage tank but have attachment nodes on the bottom for multiple engines of smaller diameter.  The best part, however, is that they also have extra stack nodes down below where the bottoms of the smaller engines would go.  These latter nodes all you to attach a single full-diameter stack decoupler below all the small engines, and the decoupler fairing will be the full tank diameter, covering all the small engines neatly.  MOLE has 2.5m and 1.8m adapters that do this and allow for multiple 1.25m and 0.625m engines.  Each of these is a single part for each size, with the ability to vary the number of nodes for the small engines.  Space-Y has a collection of such parts, all separate, 1 for each combination of big to X # of small, but these are mostly of larger initial diameter, like 3.75m and 5m as that's the focus of the mod.

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On 14/11/2017 at 12:47 AM, HeliosPh0enix said:

When I make engine clusters for the sake of a higher TWR, I usually don't use the built-in adapters.  Usually, I will take a radially-attachable nosecone and put it on 3-4x symmetry, then put the engines on the bottom.  I then use the displacement tool to push them together in the center to look like and engine cluster.  I do this for three reasons: 1) I think the partially visible nosecone looks better than the adapters 2) the nosecones don't make it less aerodynamic (as far as I know) and 3) I can't figure out a way to attach anything below the adapters (like if it were an upper stage and I need a decoupler below, I would have to now have several stacks of fuel tanks because of the inability to put a decoupler in the middle), and the above mentioned method leaves the node on the bottom of the fuel tank stack open.  I usually place a girder or two on this node until they just stick out below my engines, then put a decoupler on the end of that.  This way I can have a central stack below this for a lower stage.  The issue with this is that it is unshrouded and the two sections of rocket are joined by a thin girder.  Does anyone have a more effective way of doing this that still looks okay, or is this the best possible solution?  Thanks for any input.

Interstage fairings FTW. Make sure your decoupler is one size smaller than the upper stage tank, so that it doesn't interfere with the fairing. If you have Editor Extensions, you can even offset it down as much as you want to avoid having to use a girder. Then, place the fairing base directly below the decoupler, and build it so that it closes onto the edge of the upper stage tank. A fairing in this configuration provides additional support to the joint, so having your upper stage hinging on a small decoupler (or girder) will no longer be an issue.

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