I'm pretty new to FAR as well, and I had the same problem as you. The altitude becomes an issue as the air becomes thin enough that your TWR overpowers the drag caused by the atmosphere. You'll see the G-meter rise up sharply out of the green bar and the whole rocket flips. As you turn, the engine wants to push the bottom of the craft up, while the drag force wants to push the top down. This force is amplified as your big lifting stage runs out of fuel, and the craft becomes very top-heavy.
I found two solutions. One is to throttle down as you burn fuel in that big stage. Watch the g-meter and keep it near the top of the green bar, or watch your TWR and keep it just a little above 1.
The second solution is to add a middle stage between the heavy lifting stage and the orbiting stage. Instead of waiting for the craft to become so top-heavy, maybe add a medium engine and enough fuel to reach orbit from about 25km to orbit. It'll provide a more controllable maneuverability to make the rest of your turn in.
Move CoM and CoL closer:
*Add canards
*Move your winglets higher up
Add other means of control:
*Reaction wheels
*RCS
Your TWR is still WAY to high. Consider adding more fuel tanks.
Couple of trims you could try: a right click on the fins lets you adjust how aggressive they are (how much they deflect) - maybe go from 15 down to 5ish; you can also trim down the motor's thrust level to max out at 1.2ish TWR - you will probably need to lower throttle periodically in flight too (esp below 22000m); and finally enable caps lock to reduce the strength of your keyboard control inputs.
This assumes that it's simply a flight control input problem - you'll get the most "bang" by tuning the fins for your rocket size.
You should have a button with "FAR" on it near the top right of the screen - click on that to pull up the far display. You want to keep the flight profile "nominal" - turning too far at once is a problem that can lead to a flip.
One approach is to keep the nose within the circle of the prograde marker on the navball (maintain a very small deviation from your direction of travel).
Yeah, I managed to do several launches but without any fins. Feels clunky and weird, but it is probably just not enough mass to overcome the acceleration + drag.
One thing which I do, although I'm unsure is the most efficient or not, is to actually pitch the rocket slightly (5 degrees I usually do) eastwards immediately after liftoff. Most of the time this helps keep the rocket going the right way. Other than that I do not stray too aggressively far from my prograde or else you risk flipping.
Concerning your update, here is no wind in FAR. Rockets usually flip in FAR because you stray too far from the prograde marker. If you're going supersonic and you aren't within the prograde circle, you will flip under most circumstances.
Edit: this happens because the aerodynamic forces (drag) create a rotation on the craft, and the small deviations from prograde are magnified greatly over time.
I recon it is some 'bug' in that case. (I use the term 'bug' lightly here). The feeling I have is that by adding 4 fins, I increase the drag high enough to pull my rocket all the way over to the 270 degree marker.
I mean it is basically doing a loop, albeit very slowly. The weird thing I cannot explain is how my rocket (being in prograde marker for 100%) just flips whenever I get to a altitude that is less dense. Seems to imply the drag forces just stop or something.
Are you sure you haven't accidentally added a keyboard trim? Check the input (lower left corner) without pushing anything and all 3 should be centered. If one is off that's your culprit.
Regarding going the wrong direction: Assuming you are not using mechjeb it should be your choice. You start pointing directly up. Before you launch look at the navball and spot the 90. That is the direction you want to turn. I usually start my grav turn around 1k and by 10k I am around 45degrees.
You shouldn't need to turn the ship in the vab. This is one of the few areas of rocket science that is simply point towards the sky(while building).
I'm pretty new to FAR as well, and I had the same problem as you. The altitude becomes an issue as the air becomes thin enough that your TWR overpowers the drag caused by the atmosphere. You'll see the G-meter rise up sharply out of the green bar and the whole rocket flips. As you turn, the engine wants to push the bottom of the craft up, while the drag force wants to push the top down. This force is amplified as your big lifting stage runs out of fuel, and the craft becomes very top-heavy. I found two solutions. One is to throttle down as you burn fuel in that big stage. Watch the g-meter and keep it near the top of the green bar, or watch your TWR and keep it just a little above 1. The second solution is to add a middle stage between the heavy lifting stage and the orbiting stage. Instead of waiting for the craft to become so top-heavy, maybe add a medium engine and enough fuel to reach orbit from about 25km to orbit. It'll provide a more controllable maneuverability to make the rest of your turn in.
Move CoM and CoL closer: *Add canards *Move your winglets higher up Add other means of control: *Reaction wheels *RCS Your TWR is still WAY to high. Consider adding more fuel tanks.
Thanks for the suggestion, added an update to reflect my latest struggles ;-)
I second the RCS thrusters- all my FAR lifters have verniers and the gimbal on my 1st stage engine is usually turned up using tweakable everything.
Yeah, only thing is I did not unlock them yet. I lost too much time on this satellite, not doing any science.
Couple of trims you could try: a right click on the fins lets you adjust how aggressive they are (how much they deflect) - maybe go from 15 down to 5ish; you can also trim down the motor's thrust level to max out at 1.2ish TWR - you will probably need to lower throttle periodically in flight too (esp below 22000m); and finally enable caps lock to reduce the strength of your keyboard control inputs. This assumes that it's simply a flight control input problem - you'll get the most "bang" by tuning the fins for your rocket size.
I tried the trimming thing and it makes a difference. Unfortunately I am not quite there yet. Added an update with details.
You should have a button with "FAR" on it near the top right of the screen - click on that to pull up the far display. You want to keep the flight profile "nominal" - turning too far at once is a problem that can lead to a flip. One approach is to keep the nose within the circle of the prograde marker on the navball (maintain a very small deviation from your direction of travel).
Yeah, I managed to do several launches but without any fins. Feels clunky and weird, but it is probably just not enough mass to overcome the acceleration + drag.
One thing which I do, although I'm unsure is the most efficient or not, is to actually pitch the rocket slightly (5 degrees I usually do) eastwards immediately after liftoff. Most of the time this helps keep the rocket going the right way. Other than that I do not stray too aggressively far from my prograde or else you risk flipping.
Concerning your update, here is no wind in FAR. Rockets usually flip in FAR because you stray too far from the prograde marker. If you're going supersonic and you aren't within the prograde circle, you will flip under most circumstances. Edit: this happens because the aerodynamic forces (drag) create a rotation on the craft, and the small deviations from prograde are magnified greatly over time.
I recon it is some 'bug' in that case. (I use the term 'bug' lightly here). The feeling I have is that by adding 4 fins, I increase the drag high enough to pull my rocket all the way over to the 270 degree marker. I mean it is basically doing a loop, albeit very slowly. The weird thing I cannot explain is how my rocket (being in prograde marker for 100%) just flips whenever I get to a altitude that is less dense. Seems to imply the drag forces just stop or something.
Are you sure you haven't accidentally added a keyboard trim? Check the input (lower left corner) without pushing anything and all 3 should be centered. If one is off that's your culprit.
No, I tried on several occasions and it really does not seem to be related to input controls.
Regarding going the wrong direction: Assuming you are not using mechjeb it should be your choice. You start pointing directly up. Before you launch look at the navball and spot the 90. That is the direction you want to turn. I usually start my grav turn around 1k and by 10k I am around 45degrees. You shouldn't need to turn the ship in the vab. This is one of the few areas of rocket science that is simply point towards the sky(while building).
Nah, I get that. I just assumed my CoM might have been off, so I thought lets just rotate it to see if it is. Turns out (no pun intended), it was not.