Some questions for FAR users

[1straycat]

I'm thinking of adding FAR to my newest game (and maybe principia for more realism), but I want to be sure it won't ruin my spaceplane fun, as I love spaceplanes and want to do a mostly spaceplane career with some modded nuclear jets. I'm the type to tweak and optimize everything to death, and have wanted to try FAR for a while but it's scary complicated!

1. Can you achieve similar performance (payload fraction) with your spaceplanes with optimized FAR spaceplanes as with optimized stock SSTOs?

2. Regarding stability/maneuverability, with stock, it's possible to make a spaceplane that flies well at all speeds and SSTOs efficiently too. Is this possible with FAR? (Guessing no due to having to optimize for different flight regimes, which would be fine)

3. All the guide/tutorials I see for FAR are at least 2 years old. Are there newer guides for FAR, or has nothing changed since then? Anything you recommend in particular? Especially for making sense of all those derivatives.

4. Is the stock AeroGUI and part-specific aero data wrong when FAR is installed? I'm guessing yes, so how do you optimize your planes?

5. How do planes fly on Duna?

6. Any companion mods you consider necessary or highly recommended to build or operate optimal crafts with FAR?

[Vanamonde]

This discussion of add-ons has been moved to Add-on Discussions. 

[rhoark]

Just do it. Expending mental effort on optimizing a craft for stock non-physics is just pearls before swine.

I highly recommend procedural wings, since the shape of wings will matter.

[1straycat]

6 hours ago, rhoark said:

Just do it. Expending mental effort on optimizing a craft for stock non-physics is just pearls before swine.

I highly recommend procedural wings, since the shape of wings will matter.

I mean I did try a bit, but realized it would take a long time to master anything, so I want to have some idea of what's possible before committing a save to it and maybe finding out much later that nothing I wanted to do works.

[steve_v]

16 hours ago, 1straycat said:

Can you achieve similar performance (payload fraction) with your spaceplanes with optimized FAR spaceplanes as with optimized stock SSTOs?

Sure you can. I've been running FAR since 2013, and I do all my late-game lifts with spaceplanes. I actually find it more difficult to design sensible spaceplanes in stock, due to TWR requirements to break the mach "wall" wave-drag abstraction.
 

16 hours ago, 1straycat said:

with stock, it's possible to make a spaceplane that flies well at all speeds and SSTOs efficiently too. Is this possible with FAR?

Yes, but it will take you longer to design and require more testing. You get more design tools though.
 

16 hours ago, 1straycat said:

All the guide/tutorials I see for FAR are at least 2 years old.

Very little has changed. As for the derivatives page, green is good and red is bad. 90% of the time that's all you need to know.

 

16 hours ago, 1straycat said:

Is the stock AeroGUI and part-specific aero data wrong when FAR is installed?

Yes and no. It's certainly less useful, and I haven't used it recently enough to speak to it's accuracy.
 

16 hours ago, 1straycat said:

how do you optimize your planes?

The SPH analysis window, and the flight-data window mainly. The tint lift/drag/stall options in flight can be handy too.

 

16 hours ago, 1straycat said:

How do planes fly on Duna?

Carefully. You'll need bigger wings than stock.

 

16 hours ago, 1straycat said:

Any companion mods you consider necessary or highly recommended

RCS build aid for detailed CoM and thrust-offset information, useful with or without FAR.

 

 

[AeroGav]

On 1/24/2019 at 11:44 AM, 1straycat said:

 

1. Can you achieve similar performance (payload fraction) with your spaceplanes with optimized FAR spaceplanes as with optimized stock SSTOs?

I'm going to go against the grain here and say,  "no".

A well optimised stock airplane can have a lift to drag ratio of over 4:1,  and hold that from mach 1.7  upwards to orbital velocity.

Ferram Aerospace makes it much easier to bust mach 1, so long as your airplane is suitably swept like a real supersonic fighter.   The lower atmosphere is much less soupy.  However,  after mach 1.6 or so,  lift to drag ratio continues to decrease with increasing speed.    By mach 4 or 5 it'll be falling below 2.     That is because it does not model compression lift,  which was used on the XB70 Valkyrie (mach 3 cruise speed) and AFAIK all current hypersonic concepts.

Now, if you are building a chemical fuelled SSTO,  the limiting factor on how much fuel/payload you can burden each engine with is based on your ability to bust the sound barrier.   Once in rocket mode, you have so much thrust you can pretty much ignore drag - if worst comes to the worst,  zoom  up like a rocket and get out of the atmosphere,  then finish accelerating unburdened by drag.

I you're building a low TWR nuke engine space plane however,   hypersonic Lift to Drag ratio is EVERYTHING. 

 

[Stock Aero : Our TWR is only 0.36 to 1,  but we have a L/D  of 3.5 to 1 so we can still claw our way upwards.   7800 dv,  woof.]

I would say that it is easier to make a low drag FAR plane than a stock one though.    Just use common sense,  or copy a real fighter jet,  or turn on the area rule plot and just rearrange stuff to make a smooth line.   Stock aero is counterintuitive,  hides its logic from the player,  and tends to produce ugly, unrealistic looking aircraft.

 

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2. Regarding stability/maneuverability, with stock, it's possible to make a spaceplane that flies well at all speeds and SSTOs efficiently too. Is this possible with FAR? (Guessing no due to having to optimize for different flight regimes, which would be fine)

 

I'll go out on a limb here again and say "no".    I've seen a wide variety of designs,  but i've never seen a mach 1.6+ airplane that has a landing speed below 70 m/s.    I suspect that much of what FAR does is simply to use Voxels to calculate how "swept back"  your overall shape is,   and  use the degree of "sweptness" of your design to reduce the low speed lift and high speed drag.   Of course, this is realistic,   but the price of your easy sound barrier busting  is that if your re-entry is misjudged and you find yourself coming down over terrain other than the perfectly flat space centre peninsula,    the landing is not going to be survivable, sorry.

Stock aero,   you can make an SSTO with the low speed flying qualities of a Fieseler Storch.  Ludicrous,  but also fun.

 

[1straycat]

Thanks for the explanations! And also thank you so much for your awesome spaceplane guide. It's the one that really made me understand how ksp aero works, how to optimize with it, and the one I link to everyone. I've had so much fun with spaceplanes since then and learned a lot from seeing your other designs too 

16 hours ago, AeroGav said:

I would say that it is easier to make a low drag FAR plane than a stock one though.    Just use common sense,  or copy a real fighter jet,  or turn on the area rule plot and just rearrange stuff to make a smooth line.   Stock aero is counterintuitive,  hides its logic from the player,  and tends to produce ugly, unrealistic looking aircraft.

I actually found building with FAR much weirder when I tried. But it's not quite fair, as I feel like I know stock aero very well thanks to the above and have gotten used to relying on indicators and CorrectCOL.

Alas, FAR has taxed my framerate too much to really be viable, so I've given up on it for now. It'll be on my list for when I get a decent PC.

 

While you're here, do you know if there are any other mods or if it's possible with cfg editing to make the MK2 parts' drag values more reasonable? It was a large part of why I wanted FAR in the first place.