Spinning Rocket Error Problem

[aeromike221]

Okay so it's been awhile since I've played KSP...and I recently just started again with the new version that just came out. I've been trying to build a new interplanetary mothers-hip and designing a brand new Heavy- Life vehicle to take it into orbit. Though it's a little different, there's nothing that wrong with it. Everytime I've tried to launch it, when I start the gravity turn it spins itself out of control. Every single time. I've looked into center of gravity but everytime (just about when I've spent half my fuel on the first stage) when I start turning, it continues and spins itself out of control. At first I thought it was just an error in my design, but I've tested similar Heavy-Lift vehicles I've made before the new version came out and it does the same. Even though they worked perfectly fine before.

So what's up this. Did those bone-heads from Squad add some new changes to the game that make previous designs/or design strategies not work or is it a bug? I just need help...it ticks me off that its doing and I just want to go back to launching, exploring and landing again with having to deal this. If you guys want I can show pictures of my rockets if it matters. Thanks for any help, seriously.

[Curveball Anders]

Everytime I've tried to launch it, when I start the gravity turn it spins itself out of control. Every single time.

Slow down you go too fast (hums the rest).

And ponder that 1.x might actually force you to think (and try and fail, and think some more) while designing.

[stibbons]

Nobody can help you without pictures of your ship and a description of how you're trying to fly it.

And you should probably acquaint yourself with how aerodynamics and atmosphere have changed. If you're trying to follow the same ascent profile you used in earlier versions you're in for a bad time.

And calling people boneheads doesn't help me take you seriously.

[problemecium]

Please do not blame SQUAD for this. Many of us have made that mistake and regretted it once we figured out what to do.

The new aerodynamic model is much more sensitive to the mass distribution of the craft than the old, less accurate model was. Before, only winglets would affect the center of drag, so as long as those were behind the center of mass you would be stable. Now, ALL parts contribute to drag, so as your rocket burns through the fuel at the top, the top tanks continue to apply drag while the center of mass moves down. Eventually the ship has a center of mass near the bottom and a bunch of empty tanks causing drag at the top, and without massive amounts of winglets it's doomed to flip.

There is a solution! You have to design the rocket with the direction of fuel drain in mind, as is done with real rockets. Look for a way to make it pump fuel from the bottom to the top, or at least roughly evenly, and observe what the center of mass does in the VAB with different fuel levels in the tanks. The rocket should keep its center of mass closer to the front while flying. Unfortunately there is not currently an indicator for the center of drag, so you just have to estimate it and run some tests.

If you're at the beginning of Career Mode and don't have the fancy fuel flow stuff, have a look at this: http://forum.kerbalspaceprogram.com/threads/119232 (No this is not just a plug. It'll really help).

[CattyNebulart]

Unfortunately there is not currently an indicator for the center of drag, so you just have to estimate it and run some tests.

Sure there is, just not in the hangar, try playing with aerodynamic forces turned on (F11 or something, one is heat one is aero forces) and look at how the red arrows cause you to fly out of control.

The quick simple fix is to just slap on more boosters, go straight up till ~30km and then to a gentle turn where there is less air, it costs more fuel butyou will have less aero control issues. Won't alwyas work but most of the time it does, and it is a very kerbal solution.

[sal_vager]

Aerodynamics have changed, you will have to learn some new tricks and unlearn the old ones, this is not bone-headed.

[aeromike221]

Thanks for your informative reply. I'm sorry if people were angry by some of my vernacular but mind you this is the first time I've played in months...so having everything changed from last time proved to be quite frustrating. I knew it had something to due with the fuel drainage and the center of gravity but I was confused and went my previous designs started to spin wildly I got fed up and I came to here because I didn't know if it was a bug or some squad changes which obviously now it is. I greatly underestimated the changes done unto aerodynamics.

My typical launch approach was to escape the bottom layer of the atmosphere going straight up and then aiming for the 45 degree mark(East) after passing through the second layer and gradually to zero. Here is a picture of my vehicle. The payload is the middle (the engine is not suppose to fire). Mind you that I'm showing you the second stage configuration. I had a first stage design in mind but I'm not going to implement it until I solved the spinning.

On the outside are 12 rockets with mainsail engines, designed to give the final push into orbit.

Can anyone give me some advice with the fuel drainage and launch approach.

Edited May 10, 2015 by aeromike221

[ZooNamedGames]

Thanks for your informative reply. I'm sorry if people were angry by some of my vernacular but mind you this is the first time I've played in months...so having everything changed from last time proved to be quite frustrating. I knew it had something to due with the fuel drainage and the center of gravity but I was confused and went my previous designs started to spin wildly I got fed up and I came to here because I didn't know if it was a bug or some squad changes which obviously now it is.

My typical launch approach was to escape the bottom layer of the atmosphere going straight up and then aiming for the 45 degree mark about passing through the second layer and gradually to zero. Here is a picture of my vehicle. The payload is the middle (the engine is not suppose to fire). Mind you that I'm showing you the second stage configuration. I had a first stage design in mind but I'm not going to implement it until I solved the spinning.

On the outisde are 12 rockets with mainsail engines, designed to give the final push into orbit.

Can anyone give me some advice with the fuel drainage and launch approach.

http://images.akamai.steamusercontent.com/ugc/545277988768293406/B96DD07E3CDAB0B16C54EEC4EDD6CC87887DA49C/

http://images.akamai.steamusercontent.com/ugc/545277988768293926/BF3338EEFB4687994CED24D5320F36B26EC1056A/

Yeah- your asparagus staging. That doesn't work anymore- to stabilize you'd need massive fins. The aerodynamics have changed significantly- now it's more realistic. Sadly to say you've learned very bad habits when constructing rockets- for one your using asparagus staging (a method that was barely effective in the OLD aerodynamics)- you didn't use a fairing for your payload (but hey- you might not know of it, so I can't blame you for it (but from now on use them!! They help!)).

If you want I could help teach you how to build more reliable, stable and effective rockets to launch your payloads. If not- I could just make the payloads for you. So I hope you find my post informative and maybe even take me up on one of my offers.

[aeromike221]

Yes! I would love to learn better, more efficient design principles. Thanks so much for your kind offer!!

[SRV Ron]

Aerodynamic drag on the nose of the ship changes rapidly when approaching the sound barrier in the lower atmosphere. Also flying the pre 1.0 profile is a recipe for flipping out. You can start the turn early and gradually and keep the speed down until you get through the lower atmosphere.

Also, be aware that some engines, such as the LV-N and the LV-909 are next to useless in the low and mid atmosphere.

In short, flight conditions are closer to real life. Relearn how everything works and your space program will become successful again.

[Juicy]

Asparagus still works, but you'll want to start out with a regular 2-4 stage "tall" rocket, and add the asparagus setup only to the bottom stage. There is a turning point somewhere though, where an asparagus might get too big for even the tall component of your rocket to compensate the mass distribution. As such, I don't really see them as part of the rocket, but more as a "detachable vertically accelerating rocket slinging platform". They're just there to give my actual rocket a higher altitude and some initial velocity before it really takes off