separatron: correct placement to avoid unplanned rapid disassembly

[birrhan]

I have eschewed separatrons explicitly because (a) without using them I normally can shed spent stages vertically, without issue, and ( every time I do try to use them, it results in the aforementioned unplanned rapid disassembly. So I am requesting pictures of your separatron arrangement, specifically on SRBs. How to?

[Cashen]

Typically I place them firing horizontally towards the center stack of the rocket, to push the spent boosters laterally as far away from the core stage as possible, like this:

I forget if those solid ullage motors are from KW or Nova, but the stock seps work the same way. They are angled to point slightly off to the side, not directly at the core, so they aim into the gap between the core and the adjacent booster.

[Nurph]

At the top: Nope

At the bottom: Nope

In the middle: 10 outa 10

I usually place thrusters like this:

Ideally, you want them to thrust into the Center of Mass of the booster to avoid rotation. For multipart boosters you'll just have to guestimate where the center is at.

[sojourner]

RUD

Rapid

Unplanned

Disassembly

[lammatt]

the only correct placement method of separatrons is

- putting ~10 of them on a spaceplane firing backward to gain an extra thrust boost for a second or two when the jets die. (yes i hate air intake spam)

[Cashen]

Ideally, you want them to thrust into the Center of Mass of the booster to avoid rotation. For multipart boosters you'll just have to guestimate where the center is at.

Alternatively you could place them in pairs at the top and the bottom to get a little extra push and ensure they're balanced, at the expense of a little more weight.

[Geschosskopf]

The goal with Septratrons is to balance them around the booster's EMPTY center of mass so the booster goes straight out sideways without tipping either way into the core. Before you can place Sepratrons, you need to know 2 things: where the booster's empty center of mass is, and where that empty CoM is with respect to the side separator holding the booster to the core. The latter is because the side separator exerts a force and if this force isn't aligned with the booster's empty CoM, it will rotate the booster up or down, depending.

So, once you've build the booster on the real rocket, memorize it or use subassembly loader to save it, then open it as a separate ship in the VAB, starting with a small probe core. See where it's CoM is, then mentally move that down a bit for when it's out of fuel (or get one of the empty fuel tank mods and build it empty). Once you know or guesstimate where the empty CoM mass, see where the separator is attached relative to that. Count it s 1 set of Sepratrons and balance it by adding real Sepratrons in the appropriate places.

Or, instead of going to all this trouble, now that you know what the general rules are, you can just trial-and-error it on the launch pad. IOW, eyeball the booster and side separator, put 2 sets of Sepratrons where you think best above and below the CoM, then give it a go. If it swings too much in 1 direction, move the Sepratrons on the other end our or the ones on that end in and repeat. This way is usually faster than trying to figure out where to put them using the detailed method.

Just remember, it's a very good idea to slide the Sepratrons toward the outboard side of the tank to keep them from pointing straight at the core tank. Problem is, if you're doing asparagus, this tends to point the Sepratrons at the tanks of the later boosters. However, 1 fuel tank can withstand brief exposure to Sepratrons once, but the 2nd time usually blows them up. Thus, the later boosters can usually shrug it off but if the core tank keeps gets baked by all the boosters, eventually it will pop.

[DerekL1963]

I have eschewed separatrons explicitly because (a) without using them I normally can shed spent stages vertically, without issue, and ( every time I do try to use them, it results in the aforementioned unplanned rapid disassembly. So I am requesting pictures of your separatron arrangement, specifically on SRBs. How to?

No pictures, but you are putting the Seperatrons in the right place in your staging sequence? (I.E. with the decoupler that separates that stage?)

[BigDog]

I use different placements based on what I want to do. Look closely in the first pic and you can see the single sepratrons mounted at the tops of the orange tanks. I place them on an angle so that they spin the top of the spent stage out and down. The ones on the SRBs at the top are to blow these out and slightly up. The 2nd and 3rd pics show the results of these placements.

[Hannu]

Typically you do not need separatrons with light SRBs. Decouplers can throw them to safe distance without problems. But if you need to separate heavy boosters, for example orange tank and Mainsail, separatrons are very useful. I put one separatron about middle of booster so that thrust points about 45 degrees down. It pushes empty booster away and down from main ship. Boosters start to rotate and crashes to each other but then they are at safe distance. If you want to have more beautiful stagings, put two of them symmetrically as Nurph told, but then you have to pay some mass penalty.

[KerbMav]

The TT-70 Radial Decoupler seems the only viable option because of the distance to the core it attaches the boosters which already gives a small safety margin.

What special use do the other three have? (TT-38K Radial Decoupler, Hydraulic Detachment Manifold, Structural Pylon)

I have yet to find a way to chooes how to attach the booster as I would like to - meaning the attachment point at the booster - if the cursor is no longer on the decoupler (while holding the booster and moving it into position) the game will attach the booster to the core directly.

[BigDog]

I like using the TT-38Ks for mounting outrigger type I beams on. Also in that pic I posted all the SRBs at the top are coupled with these as well. In my limited experience as long as a booster or tank does not hit an engine it really does not matter much. I have some designs where I have SRBs that bounce off of the AV-R8 Winglets with no harm done.

[Galacticruler]

What special use do the other three have? (TT-38K Radial Decoupler, Hydraulic Detachment Manifold, Structural Pylon)

the pylon is good for seperating probes without tossing them out of orbit.

the hydraulic manifold....no clue.

the TT-38K is great for attaching tossable wings, because it is not too far from the craft.

[SRV Ron]

Hydraulic manifolds are heavy. Pylons work best at this time. TT-38 are OK for solid boosters. You most certainly want the rocket to be flying stable upon staging or you risk damage from the boosters hitting it. That includes the ASAS not causing excessive wobble as it searches for the ideal control point in the flight. Adding anything out rigged at this time can introduces spin even when well braced. That can force you to launch straight up at dawn when sending ships to the outer planets, or dusk for the inner ones.

Edited July 22, 2013 by SRV Ron

[Cashen]

The TT-70 Radial Decoupler seems the only viable option because of the distance to the core it attaches the boosters which already gives a small safety margin.

What special use do the other three have? (TT-38K Radial Decoupler, Hydraulic Detachment Manifold, Structural Pylon)

I have yet to find a way to chooes how to attach the booster as I would like to - meaning the attachment point at the booster - if the cursor is no longer on the decoupler (while holding the booster and moving it into position) the game will attach the booster to the core directly.

Attach decoupler. Attach booster to decoupler. Grab the decoupler (which will now grab the decoupler and the booster as a unit) and move it around to where you want it.

[KerbMav]

Attach decoupler. Attach booster to decoupler. Grab the decoupler (which will now grab the decoupler and the booster as a unit) and move it around to where you want it.

Me and my English are friends always not.

I meant the point the decoupler connects to the booster.