Everything feels more top heavy in 1.0

[Oddible]

Having a lot of trouble getting things up to orbit this time around (after many years of doing this). Everything seems to start toppling over pretty early after launch and then I lose control and can't keep it upright. Am I not using a high enough TWR so I'm not going fast enough? What is the difference in 1.0 that is making all my rockets tip over?

[mythbusters844]

Having a lot of trouble getting things up to orbit this time around (after many years of doing this). Everything seems to start toppling over pretty early after launch and then I lose control and can't keep it upright. Am I not using a high enough TWR so I'm not going fast enough? What is the difference in 1.0 that is making all my rockets tip over?

It's the new aerodynamics making things make sense. The way to get around this is to either keep a tiny TINY angle of attack during ascent (nearly impossible in KSP), concentrate your mass at the top of the rocket (pretty hard to do), or to add control fins at the bottom (easiest). I guess it's realistic, since look what happens when you

and there's nothing keeping the rocket from getting just slightly out of line and then being flipped over by aerodynamic forces. Edited May 2, 2015 by mythbusters844
found video

[EtherDragon]

Actually the problem you are having is quite the opposite of "top heavy."

Take a look in your VAB at the Center of Mass. You'll see that it's nearer the bottom of your rocket than the top. Also, as you empty the fuel the CoM shifts lower. By definition, your rocket is bottom heavy.

This becomes an issue because what that really means is your rocket is top-draggy. If you parked your rocket on a see-saw, and balanced it on the CoM it would have a lot more length at the nose than on the tail.

What this means is that any torque on the nose will have more leverage than the same torque on the tail. If your nose tips over just a little bit (more than about 5-degrees) the difference in drag induced torque between the nose and tail is enough to overwhelm your controls and flip the rocket over.

So, what's the answer? Tail-fins.

It turns out, the very thing that wants to flip your nose over (drag from the air) is useful for keeping it pointing strait up, if you have tail-fins. Here is an Illustrated Guide in the Tutorial section of these forums that explain what I'm talking about.

Keep flying, and stay shiny!

P.S. That doesn't discount your feeling - yes, finless rockets really do feel "top-heavy" when in-fact they are exactly the opposite.

Edited May 2, 2015 by EtherDragon

[Oddible]

I wish that was the answer but sadly it is not. I am a fin maniac. I start tipping over at very slow speeds right off the launch pad. I've been playing KSP for years and this is literally the first time I'm about to give up because I just cannot seem to understand what's going on.

EDIT: Well with this current rocket I replaces the two LV-T30s I had on the boosters with LV-T45s (same as the center rocket) and the gimbals gave me the control I needed.

Edited May 2, 2015 by Oddible

[pincushionman]

Could be too speedy in the atmosphere too, and switching the LV-T30's for the weaker, heavier LV-T45's may have helped that as well.

[basic.syntax]

Various comments throughout this thread may help.

[SkyRender]

KSP: teaching entire generations about why arrows, darts, and rockets all have fins on their back ends!

Seriously, though, unless you have a huge rocket or insane gimbal range, you're gonna need fins to keep from flipping out of control every time you point slightly off prograde.

[Jarin]

I... don't think decouplers work like that. o.o

[Oddible]

I... don't think decouplers work like that. o.o

Funny, I've been using them like that for years... what do you mean?

- - - Updated - - -

KSP: teaching entire generations about why arrows, darts, and rockets all have fins on their back ends!

Seriously, though, unless you have a huge rocket or insane gimbal range, you're gonna need fins to keep from flipping out of control every time you point slightly off prograde.

You just read the first message in the thread and didn't look at the pretty picture did ya.

[SkyRender]

You just read the first message in the thread and didn't look at the pretty picture did ya.

I admit I didn't really read that particular post in the topic; my bad. Generally I find that the out-of-control flipping is due to a lack of fins more often than a lack of gimbal-enabled engines. Your case was a surprising exception to that trend!

[Superfluous J]

Funny, I've been using them like that for years... what do you mean?

Only one of those decouplers (on each side) is actually involved in holding the side tanks to the ship. Unless you're using struts that we can't see to hold them on.

[KSK]

Taking the fins off your lateral boosters might help. RV-8 steerable fins are also very helpful if you've unlocked them.

I have a sort of similar craft that flies quite nicely:

Does a round trip to Munar orbit although it can't do a landing.

[Jarin]

Funny, I've been using them like that for years... what do you mean?

Craft attachment follows single-path-to-root-part. 3 of your 4 decouplers on each side aren't actually attaching to the outer stage, they're just... there. They'll blow off when you press space, but they're not doing much but increasing cost and weight.

[samstarman5]

Losing control at high speeds is due to more accurate aerodynamics. At higher speeds, your likeliness to stall increases to the point that if you deviate one bit, you will create turbulence that will destroy any control you have. This is even true for the best-built jetplanes. Once the SR-71 is up to top speed, it is committed to that direction until it slows back down again.

The trick (if it even still applies with the changes made in 1.0.1 and .2) is to know the speeds in atmo that it is safest for your craft to turn. This would actually encourage you to not just go full throttle right from the launch pad. Before, this was true because it was a fuel-saving measure. Now it is also true in order to allow gravity turns while in lower atmo.

As all things with KSP, this does require practice and the willingness to watch things go wrong a number of times. Get a feel for the tolerances of your craft at different speeds. There will be chances for some forgiveness where you can bring it back out of control or just prevent it from doing so, but it will be different depending on how your craft is built.

I haven't tried the patched versions of 1.0 yet, but I do hope they still leave this in.

[Oddible]

Losing control at high speeds is due to more accurate aerodynamics.

Once again, this is at VERY VERY SLOW SPEEDS 50-150, right off the launch pad with very low TWR (1.25-1.5).

- - - Updated - - -

Taking the fins off your lateral boosters might help. RV-8 steerable fins are also very helpful if you've unlocked them.

I have a sort of similar craft that flies quite nicely

Yeah I have several like this from old saves as well. Weird I'm having so much trouble this time around. I tried to use SRBs on this ship first but the (significantly more expensive) T45 boosters gave me the necessary control, couldn't keep it upright with SRBs. And yes I'm using a Pilot Kerbal (Jeb or VALENTINA!).

So you're not bringing your Science Jr back with you eh? Just broadcasting it and discarding it?

- - - Updated - - -

Only one of those decouplers (on each side) is actually involved in holding the side tanks to the ship. Unless you're using struts that we can't see to hold them on.

Thanks, years, literaly years of failed ship building thinking I was getting stability out of more decouplers!

[Superfluous J]

Once again, this is at VERY VERY SLOW SPEEDS 50-150, right off the launch pad with very low TWR (1.25-1.5).

That's really weird. All I can think is your ship isn't balanced. The one you posted looks perfectly balanced, however. Do you turn SAS on? I know that's a crazy question but I'm grasping straws here. If you have the means, I'd love to see a YouTube video of you launching and the ship going crazy in the first km of flight.

So you're not bringing your Science Jr back with you eh? Just broadcasting it and discarding it?

In .90 I didn't even bother with Jrs or goos, as they were one-use and you could get more science by just doing contracts.

In 1.0(.2) I bring 2 people, a scientist and a pilot. The scientist can reset the goo and jr for multiple uses, making them much more valuable. Then, before burning home, I toss everything but what is needed to get the science (and I guess the Kerbals) home. I almost never transmit. On those rare occasions that I remember to bring an antenna, I frequently forget to use it.

Thanks, years, literaly years of failed ship building thinking I was getting stability out of more decouplers!

No problem. I had similar misconceptions about the trusses when I started, but someone set me straight.

[CloudlessEchoes]

A safe way is to keep a 1.5 twr on your ascent. This involves adjusting it as you go up, since the higher you go, the higher your twr will go. You save fuel for higher up this way also. Just a slight lean or maybe even straight up until 26-30km. Also, although those fins add some stability, if you put on the AV-R8 Winglet I've found you can gain some serious control of your rocket, just go easy on the adjustments!

I too didn't realize how struts were used until recently... I thought they would prevent a decoupling!

[Jovus]

Try using the LV-T45 instead of T-30. Those fins don't move, so the stability they give you is purely passive - no control. The LV-T30 has no gimbal, so the only control you're getting is from the reaction wheel in the pod.

Now, with a low TWR, you're going to naturally begin to tip west, because the world is curved and KSC is flat. Since you don't have any real way to correct for this in that rocket, it will quickly go in a direction you don't want it to and eventually turn right on over to a nose-down attitude.

[Pythos]

Aerodynamics, They're such a DRAG

[MGCJerry]

Either use a gimballed engine, or fins with control surfaces. I find using both gimballed engines and fins with control surfaces on my first stage seems to drive SAS crazy on some launch platforms. Your rocket as-is, is just a dart with an engine on it and no control authority. The new aero will grab it by its ankles and shake it out for loose change and drop it on its head.

Whatever worked in old versions of KSP for years, may not work anymore.

[temporalExile]

I wish that was the answer but sadly it is not. I am a fin maniac. I start tipping over at very slow speeds right off the launch pad. I've been playing KSP for years and this is literally the first time I'm about to give up because I just cannot seem to understand what's going on.

http://i.imgur.com/z2kzlbM.jpg

EDIT: Well with this current rocket I replaces the two LV-T30s I had on the boosters with LV-T45s (same as the center rocket) and the gimbals gave me the control I needed.

Holy crap.

That decoupler thing is genius. You not realize it, but the decoupler setup you have might be one of the best ways of dealing with booster stages crashing into the main rocket...

Anyways, I've used FAR since 0.24, so I'm used to having to use fins. But I do avoid the static ones like the plague, because if you do a wrong maneuver, they make it a tremendous pain to correct it.

Edited May 21, 2015 by temporalExile

[zarakon]

A single LV-45T on the middle should be enough control.

Maybe you accidentally right-clicked and removed fuel from a tank on one side or something, so it's off balance?

[SpaceChipmunk]

Fins can occasionally help, but not all rockets require fins. A lot of the time it is about either traveling too fast or not fast enough. Changing staging can work as well, keep the weight as high up the rocket as possible by dropping stages earlier. But generally I never put fins on my rockets if I can help it. Keeping below 330m/s below 10km normally solves most problems.

[Prepper-Jack]

Holy crap.

That decoupler thing is genius. You not realize it, but the decoupler setup you have might be one of the best ways of dealing with booster stages crashing into the main rocket...

As far as I can tell, this is right. When I found out the second decoupler wasn't really attached to anything, I switched to a single decoupler. Noticed my side engines started flying into the main in turns with regularity in even relatively light turns - at least when more than a single long fuel tank was involved. I went back to a more uniform decoupling method since then, and I notice less trouble. It may not be connected, but it still seems to be applying some ejection force. Sepratrons are still preferable on deeper turns when ejected mass is on the topside - though I tend to avoid them as you should use 4 of them per stack, and each is heavier than a decoupler.

[Fiddlestyx]

I only just started playing with rockets in 1.0 (been obsessed with planes), I achieved orbit on my second try.

First try rocket flipped end over end when I went to do a gravity turn. I added fins and was successful the second go (kept my speed below 160 until after the gravity turn), did two full orbits and then landed the pod between KSC and the mountains to the north, closest I ever got to landing a pod at KSC.

Built a little plane and picked up Janelle Kerman, the first to orbit Kerbin.

Maybe I was lucky, I don't know. I like the new atmo.

Here is my ship, also it will flip over if you throttle up before the pro-grade(?) marker catches up to your ship during the gravity turn.

As you can see, you lose the fins when you jettison the first stage (after the gravity turn), because you don't need them anymore once you are that high up.

Edited May 21, 2015 by Fiddlestyx