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Ratfarts

My spaceplane keeps falling apart! Help!

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I was building a very large scale spaceplane, with custom internals inside MK3 cargo bays. The plane was more than 170 parts, probably around 200. When I first experienced the plane falling apart, it was just some clipped parts falling out of the main plane. I fixed this with a few structural connectors. I launched again and when I tried to pull up off the runway, my wings just went crazy and blew the plane up. I thought I might try again but not pull up so hard. So I reverted to launch, and my plane immediately.. well it’s kind of hard to describe. The parts were all separated from each other, but still seemed connected via invisible joints, and then separated and fell apart, some parts were sent away at extremely high velocity. After falling apart, the remains violently exploded along with the runway. I am on my phone so I do not have a screenshot. I will try and get some screenshots next time I’m on my PC.

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OK, so the MOAR STRUTS thing is kind of an in-joke around here.

If something doesn't move, but it's supposed to, you add MOAR BOOSTERS, and if something doesn't stay together, but it's supposed to, you add MOAR STRUTS.

Now, joking aside...

In the old days (pre 1.0) the aerodynamic model was extremely simplistic and struts were commonly used all over the place to hold things together.

Nowadays, we have a much more sophisticated aero model and drag matters a lot. We also have something called autostruts.  If 'Advanced Tweakables' is turned on in your settings you will get an autostrut option on the little part window that opens when you right-click a part (this is called the part action window, or PAW for short).
Autostruts, used properly, can help immensely with holding things together.

All that having been said, spaceplanes are some of the most difficult things to engineer in KSP.  There are a lot of threads around about how to build them and get them to orbit.  They require a lot of design and testing time.

It's fun and exciting to build large and complex craft, but I recommend starting with small and simple.

Pictures of the craft in question, uploaded to a free image server (such as imgur.com) and linked in a post here will allow others to see your craft and we can then dispense specific advice to address any problems with the craft design.

Good luck!


Happy landings!

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This request for help playing the game has been moved to Gameplay Questions - the forum section where this sort of thing resides.


Happy landings!

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42 minutes ago, Xd the great said:

MOAR STRUTS.

Thing is, I have no idea where I can put the struts without destroying the sleek shape I’m going for.

Also everyone that says to just add a ton of LONG BIG STRUTS everywhere, I am trying to make a sleek spacecraft called the LF-1 from the movie Venom, so I can’t really add much more than those structural bar thingies which you click a place and then another place and it makes a strut bar thingy.

Edited by Ratfarts
just edited the wording

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33 minutes ago, Ratfarts said:

so I can’t really add much more than those structural bar thingies which you click a place and then another place and it makes a strut bar thingy.

Yeah, those, just add more. Unless you are obsessed with your craft's looks.

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5 minutes ago, Xd the great said:

Yeah, those, just add more. Unless you are obsessed with your craft's looks.

The bad thing about those things is that they are very draggy. More drag means that you need more engines to get velocity, and that means more weight and even more drag, and you enter in a vicious cycle. Better use autostruts, like Starhawk sugests.

 

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5 minutes ago, Rauko said:

The bad thing about those things is that they are very draggy. More drag means that you need more engines to get velocity, and that means more weight and even more drag, and you enter in a vicious cycle. Better use autostruts, like Starhawk sugests.

 

I thought those are physicsless...

Nevermind, I may be wrong. I use KJR.

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If you have a lot of small wing pieces,  try to consolidate into fewer/ larger wings,  like the BigS.  This can both help rigidity and get your part count down for Kraken prevention purposes. Also try to avoid all clipping if possible. 

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2 hours ago, Xd the great said:

I thought those are physicsless...

Nevermind, I may be wrong. I use KJR.

They are physicsless indeed, but this doesnt mean that they have not drag nor mass. It only means that those are added to the parent part.

It is a missleading term.

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10 hours ago, Aegolius13 said:

If you have a lot of small wing pieces,  try to consolidate into fewer/ larger wings,  like the BigS.  This can both help rigidity and get your part count down for Kraken prevention purposes. Also try to avoid all clipping if possible. 

Hehe.. yeah.. I only have 2 A Type Wings tweakscaled to massive sizes with 2 Big S Tail Fins tweakscaled too. Also I can’t avoid clipping because then I won’t be able to have thrusters or the front part.

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Could you share a screenshot? Maybe there is a solution for thrusters too.

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I tend to go for efficiency over sheer size,   so there others who can advise better on very large aircraft.     This is my heaviest , 250t on takeoff

QDCIXvD.png

I use autostrut,  but also you need to try and limit the amount of force passing through each joint.     Therefore,  don't attach all the wing parts to a root wing part and have that one wing section bond to the fuselage and carry the lift forces generated by all the other wing parts.    In this design , the outboard sections connect to different inboard wing sections, each with their own connection to the fuselage,  so each wing/fuselage join is only carrying the lift from 2/3 wing parts , tops.

Also,  bending relief, something used on real airplanes.    The heavy engines (especially NERVS) are mounted direct to the wing.  If they were mounted to the fuselage,  the lift to support their weight would have to go though the wing/fuselage joint.   It may also help that the wings are all wet,  and this craft has all its fuel in the wings, which again reduces the forces transmitted vs the fuel being in the fuselage.     The fact that it's a liquid fuel only design probably helps with all this. 

download here if you want to dissect 

https://kerbalx.com/AeroGav/Monstrosity-225L

 

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