Jump to content

Unplayable after FAR


hansman1982

Recommended Posts

I have found that it is easier to get to orbit with FAR than without it. Some redesign of your rockets might be necessarry. Can you post a screenshot of the rocket that is giving you trouble?

Link to comment
Share on other sites

I used FAR for a little bit but got rid of it because of problems like the OP said.

As an example, the Zenith III (http://forum.kerbalspaceprogram.com/showthread.php/24787-0-19-1-Zenith-rocket-family).

The rocket is uncontrollable. When doing the gravity turn, it just starts spinning wildly out of control, flipping end over end. It's ridiculous. I've run into many such instances of oddity and decided since I don't use spaceplanes much I'd just remove it for now. Not worth the trouble.

Link to comment
Share on other sites

Same here, I couldn't get aerodynamic rockets to work with MechJeb, even after tinkering with the flight profile curve. I suspect that there is an incompatibility between MJ assumptions and the new aerodynamic model.

Link to comment
Share on other sites

Your rockets are probably tipping over because they are turning too fast. The engine is pushing them up rather quickly, and when they turn over the large side profile of the rocket creates a lot of drag which pushes it down and your rocket starts tumbling out of control. In real life rockets start their gravity turn much sooner than 10km up, and have a very gradual turn. If you're using MechJeb, try setting the starting turn height to 1km, and the curve to 100%. Adding some tailfins near the bottom certainly doesn't hurt either, but the biggest thing is not turning over too quickly.

These are my lifter rockets using FAR: http://imgur.com/a/VEjQq (mixed up the small one with large payload with medium sized one... oh well)

5uz30fhh.jpg

4aSW0xIh.jpg

FooWGizh.jpg

The large one can lift 70 tons into 100km orbit easily. The design is pretty simple: 3 stages to orbit. First stage fires all engines, which are cross-fed to the center (not asparagus staging, but I think it looks cooler when they all come off at once). Without FAR I usually started turning over just as these were dropped, but with FAR you should already have made some progress towards that 45 degree incline by the time the boosters run out of juice. There are sepratrons to clear away the boosters for the second stage, and they work fine even when tipped over. The second stage continues lifting the payload almost all the way to a circular orbit. In some cases it does *too* well and gets all the way into orbit -- I typically then restart the flight because second stage is not equipped to de-orbit itself and I try to avoid space debris. The third stage pops the fairings once above 70 km, and finishes pushing the payload to orbit, and then can either de-orbit, drive the payload to the space station, or sometimes it has enough dv to get a collision course to the mun/minmus.

Anyway, FAR makes rockets much easier than stock IMO, but I've always favored aerodynamic and aesthetic designs over 100% functional ones. I can even afford putting extra "dead weight" for redundant systems and safety margins. Planes are also so much better, and I can actually apply the cool aerodynamic principles my dad is always blabbering on about :P

Link to comment
Share on other sites

I will get screenshots later when I get back to the game.

As to why I use mech jeb...it's easier (and I'm guessing more realistic to actual launches (granted, I'm sure in real life the rocket scientists do a lot more work before the launch in programming the launch)). This way I can set my launch up and fire away which is nice because my computer is fairly laggy which can be a problem at times with a manual launch.

Link to comment
Share on other sites

maakey's pointing you in the right direction. Basically, if your center of drag is above your center of mass, as is the case with many, if not most asparagus designs, then turning more than a few degrees off of prograde will cause the ship to become uncontrollable because it will be as if you had a parachute attached to the front of the rocket. You can address this two ways, and you should address it both ways.

First, you need to make sure your craft doesn't have a huge amount of drag at the top of it. Nose cones on everything, and fairings around anything that isn't aerodynamic.

Second, you need to make gradual gravity turns, not the "boost to 10K and then snap turn to 45 degrees" that are so common in stock KSP launches. The farther away from prograde your rocket is pointing, the more torque the offcenter drag will cause. I remember somewhere before the great forum oops that the FAR dev said that you shouldn't be farther than five degrees away from prograde during your launch. With enough control, I could manage 10 degrees, but anything more than that, while it could be done, wasn't practical as the ship started becoming more about controlling the craft than getting anything to orbit.

Asparagus staging works fine in FAR, though it's less needed as realistic aerodynamics actually reduces the amount of delta-V you need to get into orbit. If your center stack doesn't have much mass above the height of the radial stacks, you'll need to follow the prograde closely.

Done right (and this means tweaking mechjebs ascent profile if you're using mechjeb), you can even get it to launch asparagus staged rockets.

Link to comment
Share on other sites

Thanks for the notes. It's frustrating because it usually happens shortly after liftoff and sometimes before 1 KM. I am working on it, trying to tweak the design.

It's so frustrating. Before I downloaded the FAR mod, getting to orbit wasn't a challenge (generally it was getting to orbit with enough remaining fuel to go elsewhere). Now, it's damn near impossible.

Link to comment
Share on other sites

This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...