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Rocket always flips over, even with wings


Skatelow
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So i've searched the forums and internet and couldn't really find a solution to this. I've read this post of course, but even when i added wings it still flips over.
I don't use full speed when i launch, and try to keep my TWR at about 1,5 - 2. At the start the rocket is pretty stable, but when fuel depletes it starts to go sideways.
Is this a 1.1 thing? I really don't know what i can do, i've been trying to fix this for about 2 days now. The rocket is also asparagus staged, if that's any help to solving this mystery.

Can someone help me with this?

 

kTGCPma.jpg

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It looks like the engines you're using are the static kind which do not pivot to help you exert control over the ship. There's a slightly less powerful version that does, so try removing the Reliant engines and putting Swivels on instead. 

And it looks like you have no reaction wheel parts. Try mounting one of those to apply steering torque to the ship. 

When you put fins on it, where did you put them? Can we see a picture of how you were trying to use them? 

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Welcome to the wonderful world of front / top first fuel drain.   Real rockets don't become bottom heavy as the fuel burns off, because each stage has one large fuel tank at the top and one large oxidizer tank underneath and they drain together.  So you could install a mod like TacFuelBalancer or GPOSpeedFuelPump (both extremely tiny memory footprint since they add no parts or textures).   Or you just work around it as a rite of passage like experienced Kerbalizers.

Your boosters are 2 tanks tall, when the top is empty and the bottom is full , coupled with engine mass your centre of gravity will be rather low down.

As soon as you go off prograde, everything ahead of the yellow circle is generating body lift that is trying to pull the nose further out of line.  Everything behind it is generating lift that's trying to kick it back in.   The problem with the CG so far down the rocket, is that you have far more working against keeping it straight than helping.  IOW it is unstable.   You can try mounting the largest possible wing surfaces as low down in the rocket as possible to counter this - the further behind the CG they are, the more lever arm they have to work with.

Or rework your fuel system so you don't have large shifts taking place.

Swap the smaller tanks in the core stage for FT800 but make the boosters only one tank tall? slide them down the rocket whilst adding fins?

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Might as well lose the fairing, they're pretty much useless from what I've seen. Lowering the radially mounted booster might help a bit. What exactly is inside the fairing? One or more of us could try and replicate your rocket and see what's what. Which parts have you used? If we can replicate the rocket precisely it should be relatively easy to find the issue. Exactly what engines are you using, seems like it's all Reliants on the first stage, that might be the issue actually.

Edited by Mjarf
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Post the ship file here, I'll rebuild it and make it fly. You can then study the changes I made to help future ambitions of space travel :)

(usually located here - C:\Program Files (x86)\Steam\steamapps\common\Kerbal Space Program\saves\*SAVE GAME NAME*\Ships\VAB)

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2 minutes ago, Vanamonde said:

It looks like the engines you're using are the static kind which do not pivot to help you exert control over the ship. There's a slightly less powerful version that does, so try removing the Reliant engines and putting Swivels on instead. 

And it looks like you have no reaction wheel parts. Try mounting one of those to apply steering torque to the ship. 

When you put fins on it, where did you put them? Can we see a picture of how you were trying to use them? 

All points I was going to point out :)

It does look like a very sturdy rocket however.

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Thanks everyone for the help! Really appreciate it :)

I was trying the simple suggestions first, so i changed the LV-T30 engines (which i had limited to about 75%) and replaced them with the LV-T45 "Swivel" engines. I also adjusted the fairing a little bit and made it less pointy, altough i doubt this had any influence. Really weird, but just changing the engines seemed to work, didn't adjust anything else. The rocket is pretty stable now and very easy to steer. Doesn't even need fins.

Here's the updated ship file here for if someone still wants to adjust it or use it: Download

And here's a picture of the new craft:

gPs0wPb.jpg

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