arise257

It's probably just as efficient, but I can't do the numbers right now. Something tells me your weight would be nearly identical. Read my previous posts, if it beats 1.2t with no engines (in VAB), then yes, it's more efficient from a TWR perspective. It's tough to beat the efficiency of multiple engines beneath a stack because there are no off-prograde forces acting on your rocket/engines. Every wobble/twist to the side is energy not spent going up/forward, and that's affecting your deltaV. I understand those forces are small, but over the course of a mission, that's thousands of meters peeled off your potential. I think that's really the point of this design - getting everything firing beneath the stack, and having massive thrust carried up to orbit - with minimal weight spent. From a fuel consumption perspective, I'm not sure it gets significantly better than this. I'll take that back if someone can show me why though.

Your post is welcome. I shared my design in hopes that people would poke at it or think of alternatives. If there's a more lightweight, stock, non-clip method to achieve something similar, everyone wins.

If I'm imagining this correctly, then your weight per engine mount is .555 tons. Multiplied 12 times = 6.660t. More than 5 times as heavy as what I've done, and more than double the weight of my lightest possible alternative.

I generally agree that it's more difficult for a novice builder to wrap their heads around. I can't agree with this being heavier and necessarily larger or wider. Here is why: This is significantly lighter than radial attachments. If you attach engines radially and buttress them with struts, you will also have to add a small fuel tank above the engine and run a fuel line to it. With just a fuel line (.05) and two struts (.05 x 2 = .1), a single radial expansion weighs .150 tons. That doesn't even include a decoupler for asparagusing/staging, nor the fuel tank (minimum .025+.07=.095 tons), which brings your total for one radial expansion (sans engine) to .245 tons. In my design above, I attached 12 engines, so let's say you put 12 radial attachments on your rocket. 12 x .245 = 2.94 tons. My engine assembly has 1 quad-coupler (.175), 4 bi-couplers (.1x4=.4), 4 tri-couplers (.125x4=.5), and 4 fuel lines (.05x4=.2). That equals 1.275 tons. My design is less than half the weight, and I used the smallest parts possible to calculate radial expansion like you suggest. To the point of whether or not this is wider or larger than radial expansion, I would argue it can be, if you design it that way. I could see some clever ways to keep the cluster condensed. What you see here isn't outrageously large. It's also at the bottom of the mass in general. I would argue this is far more true-to-life than the asparagused flying pyramids most people wind up designing. I don't mean to come off as holier-than-thou, just defending my design.

This is "old-school"? Oh man... that's kind of embarrassing. I thought I was on to something new with my coupler shenanigans.

I designed the same shenanigans when I was experimenting with this technique. You dodge the fuel flow issues I have with this design (note the fuel lines leading directly to engines), but you don't get moar powah.

No docking ports necessary. What you do is chose a starting coupler and mount it right-side-up to your stack. Then flip your choice of couplers up-side-down and mount it on one of the slots with symmetry on. Then connect another coupler of your choice to the up-side-down free slot. You'll have to conduct plenty of tests to figure out where to place your fuel lines, I've never had every engine light up on the first go.

I've been toying around with a new engine design for my space station. In doing so, I figured out how to link (or chain, or stack) quad/tri/bi-couplers together. With the right symmetries and designs, you can create very powerful thrusts beneath a single stack of fuel. This is especially helpful if you don't like and/or lack space or thrust for radial expansion. Also if you like to keep things stock, here's a way to do things without kludging. This particular design uses 12 engines, 8 being mini-poodles (for boost), and 4 being nukes (for sailing) -- isolated by different action groups. What do you all think? Also, am I the first to do this?

Here is my previously-mentioned space station engine, undergoing testing. As you can see, I start with a quad-coupler, extend with a bi-coupler, and terminate with a tri-coupler in order to mount 12 engines underneath the same fuel stack. All light at once, but the nukes and mini-poodles are on different action groups. I use the nukes to "sail" and the mini-poodles to "boost".

I'm perfecting a heavy launch platform for getting my space station engines to Kerbin orbit at 120,000km. The central stage uses a quad-coupler, extended with bi-couplers, terminating with a second set of bi-couplers in order to fire 8 engines, rather than the normal 4. Once all 9 parts (2 fuel tanks, 2 engines, 1 lander, 1 rover, 1 core, 1 space lab, 1 popcorn-probe-deployer) are docked/assembled in space, I can fly the whole thing anywhere I like. I'll post pictures of the central stage. I'm not sure I've seen anyone successfully stack bi/tri/quad couplers the way I'm doing it.

RCS isn't going to change the locale of the dot, but it will make it much Much MUCH easier to align to it. That said, you're actually not on the pink dot. You're sitting slightly off, and I believe it is accurately tracking the docking port you want to connect to. You need to disconnect your current docking and try again. I would also suggest a few design improvements. You can also help yourself (in the future) by not recessing your docking ports. They need to have as much clearance around them as possible. Never put them near anything propulsion-related if you can help it. The last thing you want is to come in too hot and knock your engines clean off.

It's not so much the SAS, I've done some pretty crazy dockings. I've found that 3 things really matter a lot. Making similarly-weighted modules, adding RCS to every module, and turning on RCS when you reorient. Whenever I don't use RCS, I get the symptoms you describe. For what it's worth, I'm able to move a space station at 1/10 thrust into and out of orbit, with RCS on. Without it, the modules over-flex and break apart.