Help with flying planes with FAR

[BrotatoSalad]

So, a day ago I finally updated all my mods for 0.25. Among them was B9, which claimed that it was easier to use with FAR. I've never tried it before. They lied to me. I loaded up the game and tried out a couple of small stock fighters/drones from B9. They all flew beautifully, and even did Immelman turns with complete ease. Then I built a small SSTO with a short cargo bay that I made sure to put the CoM inside and have the fuel drain equally around to avoid CoM issues. I strutted the crap out of it with the B9 invisible struts. It took forever to even make it off of the runway. Despite the perfectly placed CoL, big ass stabilator canards, and mega delta wings with control surfaces, the plane couldn't pull up at all:huh:. Even trying to made it yaw violently and randomly. I tried adjusting the CoM around a bit and adding a bigger tailplane, but it did nothing. Most of the time the nuke engine on the back connected to an adaptor fell off as soon as the plane limped off the runway. Struts did not help this problem. Next I tried flying the Heinlen SSTO, which has a noob-proof reputation. I followed my standard SSTO flight plan. Pitch up to 45 degrees right off the runway, level out at 13k meters to build horizontal speed, followed by another pitch up to 45 degrees to push the ap up above 70km, during which I usually switch to rocket power. It did do the initial pitch up, but the plane protested by oscillating rapidly along the pitch axis. When I tried to level off the plane buckled violently and went into a major stall. I'm about to give up and crawl back to stock aerodynamics if I don't find a manual or a tutorial or something. Any suggestions?

Edited November 2, 2014 by BrotatoSalad

[Taki117]

A picture of your craft with the CoM and CoL indicators would be most helpful, but with FAR it is important to design realistic. Also, with FAR, if you have too much control authority and you fly with SAS it can cause the oscillations, it is better to fly with the FAR assists.

[Alshain]

It depends on your perspective. With FAR, it is easier to fly a plane CORRECTLY. However, it does take a basic knowledge of aircraft design. Simply put, if you know how to build both Stock and FAR craft, FAR will be easier. But if you only know how to build stock, stock will obviously be easier.

Now, about learning how to build FAR. First, you may want to start with NEAR, it gives your planes the same basic properties as FAR, but is more forgiving. Specifically, you can turn a little harder and your aircraft won't fall apart and you can go from subsonic to mach without your plane changing it's flight characteristics. For example, there is no need to move fuel around to balance weight because the Center of Lift will not change based on speed alone with NEAR. What this will do for you is start a migration path, you will eventually move to FAR, but this lets you learn the basics before making such a huge leap.

Finally, about your plane. We need more info. Screenshots in the VAB with CoL, CoM, and CoT showing are a big help. The biggest cause of not pulling up off the runway is that your wheels are too far behind the Center of Mass. The wheels are the fulcrum of a lever when taking off, if the fulcrum is too far back, the plane cannot pivot. They should be just barely behind the CoM, if using the stock wheels put the CoM directly in between the two tiny "stripes" on the wheel housing. If your wheels end up too far forward and you bottom out on lift off, you need to reconsider the placement of your higher mass items on the plane to move the CoM back.

The second cause is not enough lift and/or speed. The tell tale of this is that the plane will pivot back but the rear wheels won't leave the ground before the end of the runway. It shouldn't take a large amount of lift but, like we said, pictures help a lot. Speed can be an issue because FAR rebalances stock engines to fit with it's parameters. B9 may also be working against you because it rebalanced engines to it's liking so if your using pre-built stock craft designed for FAR, they may not work when B9 is installed, his reasoning is that he wants B9 engines to act as the upper level engine. However it creates a rather nasty issue with sharing craft in that most creators will say FAR or Stock, but few say FAR with B9 if the craft only contains stock parts. My recommendation is remove B9 till you learn FAR or at least go in and delete the module manager file in B9 that messes with stock engines.

Edited November 2, 2014 by Alshain

[BrotatoSalad]

But the stock craft I tried were from B9 and were probably designed to work well with FAR. For some reason the Heinlen, a B9 craft designed for use with FAR, could not handle a simple pitch from 45 degrees down to straight forward.

[Hodo]

Alshain is right on most parts.

You can keep B9, the biggest thing is read the half dozen or more guides on how to build an aircraft in FAR on these forums. If you are still fuzzy on the concept, GOOGLE a few aircraft and look at pictures of them see how they are setup, you can pretty easily figure out what you are doing wrong from the millions of pictures of modern planes out there.

The most common mistake most people make coming from stock to FAR, is the landing gear. They set landing gear at the front and back of the plane. When in real life have you EVER seen a modern jet aircraft with its landing gear at the very back?

The next problem is most people put WAY to much fuel on their craft, most aircraft are not flying gas cans.

Lastly, CoL vs CoM, if the CoM is to far ahead of the CoL then the craft will not want to fly do to the nose of the craft being to heavy. If you have it the other way around then the tail of the craft will want to fly in the front.

You also have the issue of speed. Most people dont think about how fast they are actually going at a set altitude. They see 400m/s and think "oh that isnt that fast" then when you stop and do the conversion you realise that they are going nearly 2/3rds the speed of sound.

[LethalDose]

But the stock craft I tried were from B9 and were probably designed to work well with FAR. For some reason the Heinlen, a B9 craft designed for use with FAR, could not handle a simple pitch from 45 degrees down to straight forward.

Uhm... a sudden 45 degree change in the angle of attack a very extreme maneuver. it screws up airflow over the wings which is going to cause you to lose lift.

You say it "can't handle it". While I'm not sure what's happening, I am sure it's really bad.

[Superfluous J]

My major problem with flying planes with FAR is that you don't fly airplanes with keyboards. I seem to always have to choose between aiming too high or too low for what I want, and tilting too far left or too far right. Or, even better, wobbling between the two as I hit the keys alternately on my keyboard. Stock planes for some reason don't have this problem, they seem more forgiving to my use of keys instead of a joystick to fly.

[BrotatoSalad]

Uhm... a sudden 45 degree change in the angle of attack a very extreme maneuver. it screws up airflow over the wings which is going to cause you to lose lift.

You say it "can't handle it". While I'm not sure what's happening, I am sure it's really bad.

Either the wings would fall off or the entire plane would start randomly flipping around. Also, one design of my own plane nose-dived into the water as soon as it got off the runway. Could someone please give me the url for a FAR tutorial, because a youtube search isn't turning anything up for some reason.

[Hodo]

Either the wings would fall off or the entire plane would start randomly flipping around. Also, one design of my own plane nose-dived into the water as soon as it got off the runway. Could someone please give me the url for a FAR tutorial, because a youtube search isn't turning anything up for some reason.

Here..http://forum.kerbalspaceprogram.com/threads/52080-Basic-Aircraft-Design-Explained-Simply-With-Pictures

This tutorial is pretty much all you need to know about aircraft design in FAR.

As for your wings coming off, you were going WAY to fast and tried pulling to hard of a turn which cause the force of the air over the wings to become so great it sheared the wings off... this is what that "HIGH DYNAMIC PRESSURE" warning is on the FAR window. If you are going near the speed of sound at a low altitude, below 10km you will be basically pushing a wall of air over your craft. Changing direction suddenly will cause so much force on your craft it will tear it apart. Much like real life.

[Alshain]

Either the wings would fall off or the entire plane would start randomly flipping around. Also, one design of my own plane nose-dived into the water as soon as it got off the runway. Could someone please give me the url for a FAR tutorial, because a youtube search isn't turning anything up for some reason.

If the wings fall off your putting too much pressure by turning too hard. If it's flipping around, you've likely gone into a spin by turning too hard. No build is going to fix that, you need to adjust your flying because no real plane can do that. Never the less here is a guide that covers 95% of what you need to know.

http://forum.kerbalspaceprogram.com/threads/52080-Basic-Aircraft-Design-Explained-Simply-With-Pictures

Edited November 2, 2014 by Alshain

[Hodo]

Here is a few pictures of how most of my aircraft are set up from my Real Solar System install.

Javascript is disabled. View full album

Notice how the CoM and the CoL are near each other, and how the landing gear are just behind the CoM, almost directly under the CoL. This is the point of rotation for the aircraft on take off. If you have them to far forward the craft will just fall on its tail, if they are to far back they will not alow the craft to rotate for take off.

[MarvinKitFox]

But the stock craft I tried were from B9 and were probably designed to work well with FAR. For some reason the Heinlen, a B9 craft designed for use with FAR, could not handle a simple pitch from 45 degrees down to straight forward.

For some reason, when I drive my Honda into a brick wall at 80mph, it hurts!

Of COURSE it does!

The trick to using FAR is to

1) Design a plane that obeys aerodynamic laws, or at least a much better simulacrum of them than the stock KSP aero model

and

2) Training yourself in how to actually fly.

You seem to have neglected #2 horridly.

[Alshain]

Early on you want your CoL a bit back and down from what Hodo has, till you get better at it. His are going to be very maneuverable, which isn't bad, it just takes more control and practice flying. For a balanced stability you want your CoL to be on the same vertical level as the CoM and to be just "kissing" the back of the CoM.

Also do not forget to configure your control surfaces and select which ones are for roll, yaw, and pitch.

[Taki117]

You need to update FAR as well.

[Hodo]

Early on you want your CoL a bit back and down from what Hodo has, till you get better at it. His are going to be very maneuverable, which isn't bad, it just takes more control and practice flying. For a balanced stability you want your CoL to be on the same vertical level as the CoM and to be just "kissing" the back of the CoM.

Also do not forget to configure your control surfaces and select which ones are for roll, yaw, and pitch.

True those are all combat craft, except the Cessna design, that one actually is quite stable even though the CoL is almost right on top of the CoM. You actually do not have to have your CoL on the same plain as the CoM, you have to be careful about placing it higher or lower. The thread linked earlier pretty much explains the pros and cons of this.

The biggest thing is think about what you want the craft to do, design it to do those things, then learn to fly it.

- - - Updated - - -

You need to update FAR as well.

How do you know he needs to update his FAR, he hasn't posted a picture with anything?

[LethalDose]

Either the wings would fall off or the entire plane would start randomly flipping around. Also, one design of my own plane nose-dived into the water as soon as it got off the runway. Could someone please give me the url for a FAR tutorial, because a youtube search isn't turning anything up for some reason.

I said nothing good would happen, and none of those were good.

Wings falling off is you flying it wrong (turning too hard)

Nose-diving is probably bad design (Bad CoL/CoM balance)

Randomly flipping around is probably you flying it wrong (Stalling, bad AoA, etc), but could also easily be a bad design (unstable)

If you were flying planes with stock aero and changed to FAR, the first thing you need to learn how to do is is fly. Again. I haven't looked at the stock FAR planes, but it sounds like they're still too much for you. IMO, the best thing for you to do is build a stupid simple trainer aircraft and just practice with for a while until you get the hang of FAR. I build this little guy:

For this exact purpose (also note its from a previous patch, and the control surfaces are missing now, but whatever).

Make something small and low powered (one basic jet engine). When you can fly that safely and land, move up to more complex and higher-powered craft. Building these small simple planes will also give you a better handle on some super basic aircraft design principles.

Also, if you're just feeling lazy, you can turn off aerodynamic failures in FAR's options and deal with being a bad pilot with some more SAS.

One more thing in FAR: I'd recommend activating the FAR panel during flight (push the FAR button). It gives you warnings when you start to stall (may be causing you to flip out) and when you're getting high dynamic pressure (meaning you're close to breaking your plane from aero forces).

[Alshain]

Hodo, I couldn't agree more. If your building an SSTO for example, you may even want your CoL further back to be more stable, this would be prohibitive of turning but why would you be turning an SSTO more than enough to keep your inclination good? Your going to most likely take off at 90 degrees and keep it that way and the same for landing, or only turn to get on a polar trajectory and to come around if you miss the runway. You don't need to turn on a dime for that. Meanwhile having the CoM further back means less likely the fuel shift will cause reentry problems.

On the opposite end, if you want to take on those Fine Print aerial surveys that are becoming stock, you need to be able to turn. That is what the craft I pictured above was designed for.

[weeble]

It definitely takes some time to learn how to use FAR with any type of success.

My two biggest problems when starting was the amount of fuel and setting the control surfaces.

Jet engines are so efficient that you don't really need as much fuel as you'd think you need, especially comparing them to rockets!

Setting control surfaces is incredibly important too. If you have canards in the front set those to pitch. The wings should be roll. The tails that are horizontal should be pitch. And the vertical tail should be Yaw.

If you Google the phrase: FAR plane design kerbal, you'll get like a hundred or so pages and tutorials. Ferram also has a few good pages in his Github Wiki on SSTO and stability. Youtube is another fantastic resource that is easy to find hundreds of tutorials on as well.

[Taki117]

- - - Updated - - -

How do you know he needs to update his FAR, he hasn't posted a picture with anything?

I was referencing the album Hodo Posted, but I didn't realize it was not the OP. I was in a bit of a rush.

[BrotatoSalad]

Thanks for the info. I'll move fuel around when I get to transonic speeds to get the center of mass where I need it. It's weird how you can turn as hard as you want in stock, right? I thought a plane could do 45 degrees easily, but evidently not.

Edit: built a basic ssto and it actually got into orbit. Haven't gotten around to landing it though. On my last try I couldn't shed enough velocity and crashed in the deserts of Kerbin.

Edited November 3, 2014 by BrotatoSalad

[Wanderfound]

Thanks for the info. I'll move fuel around when I get to transonic speeds to get the center of mass where I need it. It's weird how you can turn as hard as you want in stock, right? I thought a plane could do 45 degrees easily, but evidently not.

You need to lead the plane, don't try and force it. Every time you move the nose away from prograde, do it by 10° or so, then give the prograde marker a chance to catch up with your new heading; it should only take a second or two to get back to an angle of attack of 5° or so, then you can do it again. If you need to turn a lot, you just need to keep leading it.

You can get away with much larger AoA in certain situations, but it takes a bit of experience to recognise when you can do that.

After you've read the illustrated aircraft tutorial, have a poke at posts #2 & #3 in the Kerbodyne thread in my sig. Then, build or borrow a simple aerobatic trainer (e.g. http://forum.kerbalspaceprogram.com/threads/90747-Kerbodyne-SSTO-Division-Omnibus-Thread?p=1515356&viewfull=1#post1515356) and put in some flying time while you learn the limits.

[Oafman]

My major problem with flying planes with FAR is that you don't fly airplanes with keyboards. I seem to always have to choose between aiming too high or too low for what I want, and tilting too far left or too far right. Or, even better, wobbling between the two as I hit the keys alternately on my keyboard. Stock planes for some reason don't have this problem, they seem more forgiving to my use of keys instead of a joystick to fly.

Have you tried activating precision controls, with caps lock?

If you're finding that your keyboard buttons are too sensitive this might work well for you

[ratchet freak]

I prefer using the trim controls to fly FAR, it's reeeeaaalllllllyyy slow to react but super precise (though a pain to know when you are back to neutral roll without screwing up the pitch trim)