Cant get into space with FAR

[TheJay15]

anything I make with FAR is incredibly unstable and cant get anywhere near orbit even with SAS enabled. I'm playing career mode and trying to make a rocket that is more complex than just a CM and a booster but everytime the rocket enters the 2nd stage it begins flipping and disintegrating. Its really krakening me off and Im thinking of uninstalling FAR because of this as it is really sucking all of the enjoyment out of the game.

Edited December 22, 2015 by TheJay15

[Pecan]

23 minutes ago, TheJay15 said:

 Im thinking of uninstalling FAR because of this as it is really sucking all of the enjoyment out of the game.

You've already made things hard for yourself by starting in career mode so removing mods that make such fundamental changes sounds like a good plan, what's your question?

Edited December 22, 2015 by Pecan

[TheJay15]

I was unaware that career mode was "hard mode" I assumed that it the standard game mode.

I am trying to figure out why my rocket begins to tumble as soon as it enters its second stage despite no asymmetrical drag and it flying perfectly fine before.

[Pecan]

9 minutes ago, TheJay15 said:

I was unaware that career mode was "hard mode" I assumed that it the standard game mode.

I am trying to figure out why my rocket begins to tumble as soon as it enters its second stage despite no asymmetrical drag and it flying perfectly fine before.

Career mode is the full-on game, but all the money, contract, strategy, reputation stuff makes for a much more complicated experience when you're just trying to learn how to build and fly.  If you don't like the idea of wide-open sandbox mode the best place to start is science mode, which restricts the parts you have initially and requires you to collect science in order to unlock the others but doesn't have all those other considerations.

Next, why FAR, or any mods?  An information mod like KER, MJ or VOID is great but otherwise you're mostly making the majority of tutorials and other peoples' experience and vehicles invalid for your install.

However; rockets flipping during ascent is common to all (1.0.1+/FAR) aerodynamics and there are many threads about it.  The basic causes are that there is too much drag above the CoM of the rocket or the CoM is just too low.  Darts have their mass forward and drag (fins) at the back - it works.

1. In order to fly through atmosphere properly you need to start your gravity turn early and keep the nose within (roughly) 5-degrees of prograde so the rocket is going more or less straight through the air.  At slow speed you can sustain a higher angle of attack, simply because there's not much speed-induced drag to affect the ship anyway.  Similarly, above the thick atmosphere, at least 30km up, there isn't the density of air to induce much drag.  5 degrees is a good ascent guide though.
2. Don't go too fast, as that increases the amount of drag.  A launch TWR of 1.2 - 1.4 is sufficient, max TWR <2 until you're above the thick air. (This latter very much just a guideline)
3. Make sure the Com starts high and, if possible, stays that way.  As fuel is usually consumed from top tanks first the CoM moves down - too far and the vehicle wants to fly backwards and will flip.
4. Most importantly, if you are staging-off parts they generally go from the back, where their drag was helping to stabilise the ship.  Upper stages also tend to have comparatively heavy engines for their structure/shape/size, so lower CoM.  Both are what rocket engineers call 'a bad thing'.

TL;DR - make sure each stage is aerodynamically stable; CoM forward, drag back - and don't accelerate or turn too fast.

[TheJay15]

Thank you for the advice it's good to know I'm not the only one who has the flipping problem. It may have just been an issue with the rocket being so tiny that I couldnt really alter the COM too much. also the goo capsules at the top probably didnt help.

 

The reason I am using FAR is because I always hear how awesome it is and also I want to use B9 parts including the procedural wing but their page reccommended FAR for it to function properly so I installed it.

 

I kinda assumed from what I'd heard that everyone used FAR.

[cantab]

I've had that issue. After the first stage is dropped the rocket is much shorter but the same width, and it's often rear-heavy, which makes for an aerodynamically unstable craft. There's also sometimes a coast period when you have no good control. There are a few possible solutions:

Decouple the lower stage and light the second stage engine at once, immediately gaining the control from its gimbal.

Make the second stage smaller and the first stage bigger, so the second stage flies in higher atmosphere and doesn't flip.

Take a steeper ascent profile, giving the same effect.

Put fins on the second stage to keep it stable, but watch it doesn't make things unstable on the first stage.

Spam reaction wheels on the second stage.

[TheJay15]

Yeah i dont seem to have the problem with the larger rockets just the small ones. I built a larger rocket and got a beautiful launch with multi stages. Even did a moon orbit, my first one outside the tutorial!

 

I'm now really considering uninstalling FAR but does it make the B9 aerospace parts not work specifically the procedural wings as I really like using them to make aircraft and would hate to see them go.

[Plusck]

From what I've understood from all the vids and comments, FAR was a "must-have" for serious players prior to 1.0.1.

Since 1.0.1, and especially since 1.0.5 and the further tweaks to atmospheric behaviour, I feel that there is absolutely no expectation that a new-ish player will go straight to FAR. As a long-time demo player and new-ish buyer of the new game, I certainly didn't feel the need to change the atmosphere from stock. I may do in future, but I'm sure that the first mods I install will be to help timing missions and making rocket calculations, not make fundamental changes to gameplay.

Edited December 23, 2015 by Plusck

[TheJay15]

I went back to stock and it seems like FAR is now just a sort of "hardcore mode" as the stock physics are perfectly fine just more forgiving.

[Wanderfound]

Previously, FAR provided semi-realistic aero while stock was an absolute joke.

Now, stock provides semi-realistic (but extremely simplified) aero, whle FAR provides almost-flightsim aero.

Stock is tolerable, and perfectly adequate for rocketry; FAR is still recommended if you're into aircraft.

For FAR rocketry, you just need to remember that every atmospheric stage must have some method of maintaining stability. Usually, this means either fins or gimbal. Do that, and you can launch ridiculous things, even in FAR: