Orange tanks and manifolds

[ScottyDoesKnow]

So I'm trying to make a heavy lifter, and I know the weight can cause problems but this seems ridiculous. On my last flight, one of the top tanks just fell off on the launch pad (using a set of 4 orange tanks as a payload). Orange tank in the middle with 3 orange tanks around, each one connected by a manifold, 2 struts at the top, 2 struts at the bottom, and a strut at the top and bottom connecting between the 3.

Anyone know what's happening? Album: http://imgur.com/a/OKIfk

None of the tanks in the actual lifter (the bottom) had problems, could they be yanking it apart with their struts?

[Ninjadude501]

Well, I have no clue, but you could try strutting the tops of the ones that are falling more.

[AmpsterMan]

Just hazarding a guess but it might be the lower boosters pulling the top boosters down when the physics loads/

[ScottyDoesKnow]

Well, I have no clue, but you could try strutting the tops of the ones that are falling more.

This is just after restarting my design. I kept adding more and more struts, the launch always appeared to be rock solid without wobbling, but at least one tank seems to break its manifold each flight.

[capi3101]

How many struts do you have between the tanks towards their center? It didn't look like you had any there based on your pictures. I'd go with at least two more sets, one one-third of the way up, the other two-thirds of the way up. And you might try strutting the top end of the manifold; they're not much stronger than a -38K or -70, despite their larger appearance, and all that weight may be causing a structural failure.

Speaking of which, what is your flight log saying when this happens?

[blizzy78]

Instead of strutting tanks like this:

[ ]--[ ]
[ ]  [ ]
[ ]  [ ]
[ ]  [ ]
[ ]--[ ]

try strutting them with an X like this:

[ ]   [ ]
[ ]\ /[ ]
[ ] X [ ]
[ ]/ \[ ]
[ ]   [ ]

Remember: Triangles are an engineer's best friends.

[Oggula]

In my experience, connections between orange tanks are always comparatively weak.

Try these (in no order):

1) I've seen some designs that solve this by replacing them with grey tanks, though I'm not sure if this works too well

2) Strutting does sometimes work

3) Many designs also distribute the payload around the top of many orange tanks, because if you put 200T on top of one orange tank the link is very likely to break.

4) Some designs also attach launch clamps (and struts) to girders extending from the payload to hold it more steady

5) I personally find optimising/reducing the size of the payload and fitting it on a 1M launcher is the most reliable option. The only reason I currently field orange tank launchers is for missions landing on all the Joolian moons in one round trip.

[ScottyDoesKnow]

It's always always always the radial decoupler/manifold that fails. My usual strutting for those connections was one strut at the top and one at the bottom.

Here's the current setup that still fails: http://i.imgur.com/uWZU3Jh.jpg

One straight at the top, one straight at the bottom, 4 crossed top to bottom (2 each side).

[Taki117]

Why not assemble in space? Instead of having such a large payload, you can use clamp-o-trons (Sr. if you have it) on the side. Then launch and set up a stable orbit. Rinse and repeat until your ship is assembled. (If you have more than one clamp-o-tron they will all dock at the same time assuming they are in the right position)

[ScottyDoesKnow]

How many struts do you have between the tanks towards their center? It didn't look like you had any there based on your pictures. I'd go with at least two more sets, one one-third of the way up, the other two-thirds of the way up. And you might try strutting the top end of the manifold; they're not much stronger than a -38K or -70, despite their larger appearance, and all that weight may be causing a structural failure.

Speaking of which, what is your flight log saying when this happens?

Tried adding a strut just above and below the radial decoupler, a strut on the top and bottom of the decoupler to the tank the decoupler is attached to, and a strut on the left and right of the decoupler to the tank attached to the decoupler. Still fails.

It seems like something strange is happening, maybe with the lag. I actually got it up into orbit, just got a lucky launch and nothing broke. This was before all this reinforcement too, so it feels like it shouldn't break this easily after the reinforcement. On one of the launches, the command pod right at the top broke off when the ship finished loading, which makes no sense. So something seems weird.

Why not assemble in space? Instead of having such a large payload, you can use clamp-o-trons (Sr. if you have it) on the side. Then launch and set up a stable orbit. Rinse and repeat until your ship is assembled. (If you have more than one clamp-o-tron they will all dock at the same time assuming they are in the right position)

I know there are better ways to do it, and I did get it up into orbit. It just feels like it shouldn't be failing in this way, it's mostly curiosity. Though it would be nice to make the launcher more reliable if I want to replace it later.

The one piece design makes it a nice lazy one launch refueling station: http://i.imgur.com/g0JwWFr.jpg

[AnalogAddict]

I've had pieces and parts get literally trapped in 3d space. When you try to take off the piece of the craft literally stays hovering x meters above the launch pad.

Each time this happens to _me_, its a 110% chance that a strut was placed inside of some object. I find that its best to rebuild the offending section of your ship to ensure good new code on the .craft file. As this is a beta game I suppose it could be any number of things occurring which are breaking your structural integrity.

[capi3101]

Blizzy78's given you some good advice - also, did you try adding the strutting I suggested to the tank? I saw where you added it to the decoupler to no effect.

Next question: do your structural failures always occur on the pad prior to launch?

One last thing - I see a bunch of struts running from the booster to the center stack of the payload - how many are running to the outboard tanks? The pics are a bit fuzzy on that one - I only spotted two per tank.

Odd structural failures do sometimes just happen with larger rockets. Why? Who knows. My Thanatos Heavy 7 booster incorporates clusters of SRBs on the lower stage; occasionally a single SRB will just break loose for no apparent reason whatsoever. Always annoying when it happens, especially since it doesn't happen often.

Edited October 25, 2013 by capi3101

[blizzy78]

Most of the time it also helps to pay really close attention to what happens on the launch pad. As soon as the craft has finished loading, zoom in so you can see everything. Then, wait for the physics to kick in, which usually causes a slight wobble. Look out for parts that wobble despite of the rest of the craft being still. Those parts usually need a few struts.