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Must I give up on KSP? I do not want it :(


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I've been trying for a week to put a rocket in orbit in 1.02. And I insist, like many others, my troubles started with 1.02. For anything bigger than the 2.5 basic rocket (lets say, a SLS lookalike) the tumbling is totally out of control, sometimes happening in the upper atmosphere when the vectors from the debug menu don't even appear anymore!

This did NOT happen in 1.0, and yes I experience this with and without mods, using fairings or not, etc... The biggest fins are no help here.

I came back from a long pause for 1.0, but I give up for now.

Interesting. I have had very little trouble getting rockets of any size into orbit in 1.02, but I have noticed that small rockets are more prone to flipping, usually due to going too fast in the lower atmosphere or lack of control surfaces.

Why don't you post videos or pictures of your launches? That way we can try to help you.

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Interesting. I have had very little trouble getting rockets of any size into orbit in 1.02, but I have noticed that small rockets are more prone to flipping, usually due to going too fast in the lower atmosphere or lack of control surfaces.

Why don't you post videos or pictures of your launches? That way we can try to help you.

Agreed 2.5 and 3.75m rockets are easier to fly than smaller ones.

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Try turning more gradually. Turning to 45 degrees at 10 Km is too sharp a turn IMO. Keep the centre of the orange marker inside the yellow prograde marker until you're in the thinnest part of the atmosphere (I don't know; like 30-35 Km). I don't know whether that's efficient but it's certainly easy to control.

Tailfins at great for stability but they suck for turning. Tailfins skid the back of your rocket sideways, they don't really "turn" your rocket.

Try putting control fins in the middle close to the center of mass. and have none control tail fins for stability.

http://www.aerospaceweb.org/question/weapons/q0158.shtml

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Death to pancake rockets and abrupt gravity turns!

It's really simple:

1.) Make it aerodynamic (look at real rockets as a guide, use fairings!)

2.) Finesse your turn along the prograde, you lumbering brute. Seriously, it's ONE KEY you have to TAP (not hold). A chimp could quite literally do it.

If people still can't get rockets into space, it's not that they aren't able - it's that they refuse to adapt and prefer to whine about it.

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Perhaps it would help some people to visualize their rocket as a kayak pointing upstream and the airflow the current of the river. What happens if you abruptly angle your kayak into a strong current?

All of that fast-moving water will slam into the leading edge of the kayak and spin you around your CoM like a mofo, ie. flip your rocket.

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I actually like the update, and how you are supposed to put objects that can't survive reentry in these service module things. It makes the game feel more realistic, and it makes your rockets less ugly, and c'mon!! WHO DOESN'T LIKE THE FAIRINGS UPDATE!!?

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Perhaps it would help some people to visualize their rocket as a kayak pointing upstream and the airflow the current of the river. What happens if you abruptly angle your kayak into a strong current?

All of that fast-moving water will slam into the leading edge of the kayak and spin you around your CoM like a mofo, ie. flip your rocket.

Not bad except it is more like your kayak is going over a water fall. fast strong currents to zero in a blink of an eye.

The new effects make use of drag and lifting bodies. So any rocket that is on an angle is actually getting some lift from the atmosphere.

The problem is when that atmosphere disappears, suddenly and you don't have the lift anymore so it is all down to momentum to keep you going in the same direction or you where trying to turn and suddenly no resistance , the result is the same a flip.

I ran a test last week for fun to see if I could measure the atmo with the barometer.

it came up with this;

1km = 86 % Atmosphere/ 2 = 74 / 3 = 63 / 4 = 54 / 5 = 45 / 6 = 38 / 7 = 31 / 8 = 26 / 9 = 21 / 10 = 17 / 11 = 14 / 12 = 12

So you can see that your pressure is dropping like a rock so you are going from fighting the atmosphere to nothing really fast.

Edited by Korizan
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My god, are we still whining about this?

Personally I think the game has improved since earlier versions.

On some level, all of us think of ourselves as scientists or engineers, else we wouldn't be playing this game. Isn't the point of science to adapt to changes in experimental data??

Grow a set and be a scientist.

This. It took me all of a handful of launches to adjust my building and flying style. It really is not that hard, although new payloads and different missions keep requiring me to adjust my designs. I welcome the fact that I have to think about how I engineer my rockets and payloads rather than just slapping on a lot of tanks and other junk, pressing z + spacebar and sitting back for two minutes.

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I managed to flip rockets in mid air multiple times and still make it to orbit.

Always happens to me after v1.0.x and instead of actually feeling irritated about it, I realized this actually boosted the essence of "Kerbal" in Kerbal Space Program. I like it.

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Answer are always the same.

1.) Make it aerodynamic (look at real rockets as a guide, use fairings!)

2.) Finesse your turn along the prograde, you lumbering brute. Seriously, it's ONE KEY you have to TAP (not hold). A chimp could quite literally do it.

Its not only quite mean, its basically what I do since 1.0! Even limiting my angle of attack to something like 2° (with and without mechjeb) and tinkering with the throttle is NO USE!

Thats the rocket I have the most trouble with:

d5PTgap.png

(Generic 27T payload meant to simulate a complete SDHI system, which is not updated yet)

I tried countless launch profiles, from Manley's way to every advice on the forum, I tried to add fins everywhere, but it always spins out of control around 10KM or before, sometimes aven AFTER, ine the upper atmosphere.

So we have the parts for an SLS lookalike but its now impossible to fly?

BTW I have no problem with smaller rockets when limiting the acceleration.

Edited by Initar
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Answer are always the same.

Its not only quite mean, its basically what I do since 1.0! Even limiting my angle of attack to something like 2° (with and without mechjeb) and tinkering with the throttle is NO USE!

Thats the rocket I have the most trouble with:

http://i.imgur.com/d5PTgap.png

(Generic 27T payload meant to simulate a complete SDHI system, which is not updated yet)

I tried countless launch profiles, from Manley's way to every advice on the forum, I tried to add fins everywhere, but it always spins out of control around 10KM or before, sometimes aven AFTER, ine the upper atmosphere.

So we have the parts for an SLS lookalike but its now impossible to fly?

BTW I have no problem with smaller rockets when limiting the acceleration.

My first thought seeing that is that it looks short and bottom heavy. How low is the center of mass after you empty the first stage fuel tanks?

Easiest solution would be to add control surfaces near the engine.

Btw I'm saying that looks short since for example Falcon 9 is around 60m tall with a diameter of 3,66m. This one looks something like 30m / 3,75m.

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How low is the center of mass after you empty the first stage fuel tanks?

Around the white upper section, so not so bottom heavy ^^ . Pre 1.0 I used 1 more small 3m fuel section, but since we need less delta-V now...

Easiest solution would be to add control surfaces near the engine

As I said, been there done that, but no amount of fins will fix this...

Switched to FAR for the time being, now its hard but it works, just like in 1.0. No more devilish tumbling.

Edited by Initar
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Around the white upper section, so not so bottom heavy ^^ . Pre 1.0 I used 1 more small 3m fuel section, but since we need less delta-V now...

As I said, been there done that, but no amount of fins will fix this...

Switched to FAR for the time being, now its hard but it works, just like in 1.0. No more devilish tumbling.

If I was home I could actually try this out and then try to help with the problem but for now I can only make guesses. My assumption is that since center of mass is quite low the drag on the nose causes the rocket to flip.

Do you actually need engine that big? If you created something more like the Delta IV Heavy (http://en.wikipedia.org/wiki/Delta_IV_Heavy#/media/File:Delta_IV_launch_2013-08-28.jpg) with orange tanks and mainsails, would that work and have enough delta v?

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If it looks like it is an unstable disaster of a rocket, it probably is. Do those engines even have thrust vectoring?

I remember fighting the gimbal on those and saved the situation by dropping the gimbal slider to 1/10th or so.

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If it looks like it is an unstable disaster of a rocket, it probably is. Do those engines even have thrust vectoring?

Why is everybody aswering so aggressively in this thread? Did you even read my previouys posts?

Its not unstable, flied perfectly in 1.0, flies pretty well with FAR. Yes engines have thrust vectoring. Thrust is limited (tried different settings). Yes, I tried fins. Yes it happens with all kind of configurations and rockets. Virtually evry rocket behave like that CoM speaking. It happens even with a much lighter payload.

It feels like half of the people are complaining about something in the 1.02 aerodynamics, while the other half thinks there's nothing wrong and blame the other's skills (although some try to help). There's something rotten in the kerbal kingdom... Initar out.

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If it looks like it is an unstable disaster of a rocket, it probably is. Do those engines even have thrust vectoring?

That rocket does not look like an unstable disaster to me, it looks like a reasonable design that should work. Powerful thrust vectoring engine, much taller than wide, etc.

Initar, what happens if you disable the upper 3.75m tank until it is needed? I think that would help keep the CoM further forward and the rocket more stable.

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Answer are always the same.

Its not only quite mean, its basically what I do since 1.0! Even limiting my angle of attack to something like 2° (with and without mechjeb) and tinkering with the throttle is NO USE!

Thats the rocket I have the most trouble with:

http://i.imgur.com/d5PTgap.png

(Generic 27T payload meant to simulate a complete SDHI system, which is not updated yet)

I tried countless launch profiles, from Manley's way to every advice on the forum, I tried to add fins everywhere, but it always spins out of control around 10KM or before, sometimes aven AFTER, ine the upper atmosphere.

So we have the parts for an SLS lookalike but its now impossible to fly?

BTW I have no problem with smaller rockets when limiting the acceleration.

Can you upload the .craft file? I'd like to launch your rocket, and if successful I will share how I did it.

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Can I get a part list from top to bottom. The picture helps but to replicate I need the exact parts.

In other words what is under the fairing (AE-FF3) ?????

Why because I want to try and make the thing fly myself (I will use mechjeb) if I can then I will tell you what I did if I fail then you will get those results as well.

Edited by Korizan
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My first thought about the posted rocket is it looks like it will spin out when the boosters stage.

Even with Nu-FAR I'm finding I need to have more control authority than before. I put fins on all the things that will be there under 40km and a hefty torque wheel on stages after that.

How many torque wheels do you have on it?

When exactly does it flip?

Have you tried moar fins?

I find sometimes that excess thrust near the end of a stage can cause issues in the upper atmosphere at the start of the next. You build up such a drag that the next stage can't stop it flipping without fins no matter the amount of gimbal.

I'd say upload the craft file and lets see all the people claiming it's easy launch it in stock 1.0.2...

EDIT : also strut your boosters. A couple near the top is enough most times. They can flex during thrust and this can put odd forces onto your craft that stop quickly when they stage and this can cause odd spinning behaviour.

EDIT 2:

Have a look at this thread, it seems pertinent.

Edited by John FX
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Building that rocket as shown resulted in a nice stable design for me on an unmodified 1.0.2 install, all I did was gently pitch over once I had exceeded 100m/s, and kept the G forces below 2 by throttling back the Mammoth.

I assume that's a Skipper under that fairing, and one change I did make to the design though was the addition of two struts to those boosters, if they are allowed to flex on those radial decouplers (looks like you're using the small ones btw) you will have off-axis thrust and you will have trouble compensating.

zNpoTW5.png

Edited by sal_vager
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Success !!!!!! (Mechjeb 2.5.0.0)

Rocket (not sure what is under your fairing) sooo...

[uF] = Under Fairing

Core rocket

Mk7 / Advanced Reaction Wheel Module, Large / X200-32 Tank / X200-8 Tank / RE-I5 Skipper [uF] / Rockmax Decoupler [uF] / AE-FF3 Fairing / S3-7200 Tank / S3-14400 Tank / S3- KS-25x4 Engine

Boosters (2)

Aerodynamic Nose cone / S1 SRB-KD25K (Hydaulic Detachment Manifold )

This thing has LOTS of power show 23.19 m/s Acceleration on liftoff sooo

Mechjeb

Assent Guidance

Limit Acceleration: 20 m/s

Force Roll - defaults (need to turn it over because of boosters or turn it on build)

Edit Ascent Path

Turn Start altitude: 0.5 km

Turn End Altitude: 60 km

Final flight path angle: 0

Turn Shape: 60

----------------

End fuel in first stage @ 80km orbit 160 / 6480

Will try to refine that some should be able to get more from this rocket NP.

Let me know what is under that fairing and try my settings, but it looks like your rocket is just fine :)

Edited by Korizan
Changed limit Acceleration
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After some testing with Limit Acceleration: 20 m/s / Turn Shape: 60 / End fuel 1st Stage: 160 / 6480, I got some interesting results.

Limit Acceleration: / Turn Shape / End fuel 1st Stage

20 / 40 / 328 --------- 17 / 40 / not tested

20 / 45 / 338 ------ 17 / 40 / Failure Roll

20 / 50 / 250 -------- 17 / 50 / 207

20 / 55 / 194 ------- 17 / 55 / 212

20 / 60 / 160 ------- 17 / 60 / 175

20/ 65 / 105 ---------17 / 65 / Not Tested

------------------------------------------------------

As you can see there is a very fine line between max fuel efficiency and failure (3m/s to be exact)

So I wouldn't feel bad about having your rocket roll.

Also I noted some heating and air resistance on the 20 m/s flights.

So personally I would take the 17 / 55 / 212 profile as it appears to be reasonably safe and a good fuel efficiency.

But the choice is yours and happy flying :P

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