[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18

[Alshain]

I would hardly call FAR a ridiculous extreme. While I too would like a description of what to do in the case of red numbers, you can still get an awful lot of successful design done just by looking at the first tab's graphs, keeping your lift/drag ratio sane and making sure the yellow line does not ever rise above 0.

I don't want a dumbed-down atmosphere. It's way less interesting.

Most of my aircraft's graphs do that, they just don't fly. I think I understand the basic idea of the graphs, I can get in the air, but once I'm there I can't control it. So my choices are 1. post every aircraft here so someone else can build it for me. 2. Go back to flying boxes. That's what I call a ridiculous extreme.

All I want to know is what the numbers mean. If any given one of those numbers is Red, what is the general problematic effect of that. Will it push my nose down, up? Sideslip? That's all. Apparently nobody knows, because even the author of the plugin thinks it's all "mysterious". Possible solutions would be helpful to, should I move the wings, the engines, the canards? whatever. But at the very least I need to know what they mean.

Edited July 1, 2014 by Alshain

[jrandom]

I've been reading up on the math of flight. It's mad. I don't understand most of it yet.

But I can easily build very successful aircraft. Could you post some images of yours that are failing in flight (with CoM, dry CoM, and CoL visible? dry CoM can be seen with RCS BuildAid)? I might be able to spot something that needs tweaking.

[Alshain]

I've been reading up on the math of flight. It's mad. I don't understand most of it yet.

And that right there is why it's a ridiculous extreme. My biggest fear is Squad is going to implement this for their aerodynamics which would be a disaster for KSP.

I'm not at my gaming computer at the moment, maybe later today. But really if I have to have someone else build it for me, I'm not going to bother. I might as well use mechjeb to fly it too. That takes away all the entertainment value. I want to understand this, but it's not looking likely.

Edited July 1, 2014 by Alshain

[Starwaster]

If a part (control surface with the FARControllableSurface added) has animated flaps, how might I make those flaps useful?

I want to increase both its lift and drag, right? There doesn't seem to be a way to just configure a control surface to arbitrarily add lift/drag.... unless maybe I just altered its parameters when it's animated. (I can do that with DREC's ModuleAnimation2Value)

But what would I change? Increase MAC to reflect the increased length and decrease e to increase drag? Am I correctly interpreting the results of those actions?

Edited July 1, 2014 by Starwaster

[AdmiralTigerclaw]

And that right there is why it's a ridiculous extreme. My biggest fear is Squad is going to implement this for their aerodynamics which would be a disaster for KSP.

I'm not at my gaming computer at the moment, maybe later today.

I agree and disagree with you. Personally, I love FAR. But I'm an aviation geek to a certain level. However, FAR does its best to bring real aerodynamics to the game. Extremely sophisticated mechanics even if you don't worry about the math that can be counter intuitive if you haven't at least geeked out on aerospace designs a little bit.

One thing that does need to happen though is that Ferram needs to revise his help buttons. His translation from Aerospace Engineer to Layman is horrible, and I say that as someone who's spent over a year translating electronics to Layman for fellow students in lower courses. I make sense of the values, but only after a few seconds of back and forth between them and the help button each time.

Heck even a little bit would help. Like the tooltips that pop up and say 'this should be positive'. It should have an example of what makes it go wrong like: 'This can be caused by too much lift near the nose of the plane.'

[jrandom]

And that right there is why it's a ridiculous extreme. My biggest fear is Squad is going to implement this for their aerodynamics which would be a disaster for KSP.

The math for spaceflight is also pretty intense, but I don't see you complaining about that. You don't need to understand the actual math to build workable planes in KSP/FAR, just like you don't need to know the math to build successful rockets.

A better layman explanation of the stability numbers would be nice, but you don't need any math to be able to build flyable planes in KSP/FAR -- that can be done purely visually via CoM, CoL, and for planes that fly very fast, that first tab with the graphs.

If your planes don't fly, there's either something very wrong with the baseline design (which I won't know until I see images), or you're simply flying too fast too low (or too slow at higher altitudes). If your wings are ripping violently off of the plane, that's going to be the culprit -- too much dynamic pressure on the wings. If this is the case, fly slower at lower altitudes, and higher if you want to go all zippy-fast.

* Example of a plane with too little yaw authority slipping sidways into a mach 3.7 airstream.

* Example of a revision of said plane that fixes the yaw stability problem.

Both remain perfectly balanced throughout their entire fuel usage. RCS BuildAid's dry-CoM marker is extremely useful for doing this. (No screenshots of those at the moment, but I can make them if you want to see precisely how those aircraft are designed. I did not use any of the FAR graphs or numbers while building these, either -- it's strictly visual CoM/CoL design work.)

Edited July 1, 2014 by jrandom

[Alshain]

The math for spaceflight is also pretty intense, but I don't see you complaining about that. You don't need to understand the actual math to build workable planes in KSP/FAR, just like you don't need to know the math to build successful rockets.

That's because KSP doesn't implement "real" spaceflight. It's only semi-realistic, but made simpler so people can actually play it as a game. That's what I meant by my desire for a "gamers" aerodynamic package.

A better layman explanation of the stability numbers would be nice, but you don't need any math to be able to build flyable planes in KSP/FAR -- that can be done purely visually via CoM, CoL, and for planes that fly very fast, that first tab with the graphs.

If your planes don't fly, there's either something very wrong with the baseline design (which I won't know until I see images), or you're simply flying too fast too low (or too slow at higher altitudes). If your wings are ripping violently off of the plane, that's going to be the culprit -- too much dynamic pressure on the wings. If this is the case, fly slower at lower altitudes, and higher if you want to go all zippy-fast.

* Example of a plane with too little yaw authority slipping sidways into a mach 3.7 airstream.

* Example of a revision of said plane that fixes the yaw stability problem.

Both remain perfectly balanced throughout their entire fuel usage. RCS BuildAid's dry-CoM marker is extremely useful for doing this. (No screenshots of those at the moment, but I can make them if you want to see precisely how those aircraft are designed. I did not use any of the FAR graphs or numbers while building these, either -- it's strictly visual CoM/CoL design work.)

Well first off, I'm not talking about planes that don't fly (I mentioned that earlier). I'm talking about planes that don't fly well. I don't have any issues with the wings ripping off, I just get up to altitude and need to level off and increase speed before losing intake air and during that process I lose control. I have been able to get into orbit, but just barely and with so much fuel, there isn't enough left to de-orbit. In that case I didn't lose control, I just couldn't pull up quickly enough to take advantage of the speed I built. But that was just one case, most of the time the thing wobbles out of control and won't fly straight or I can't pull up at all beyond a certain elevation.

At the very least I have to get to 150km and have enough fuel to rendezvous.

Edited July 1, 2014 by Alshain

[AdmiralTigerclaw]

That's because KSP doesn't implement "real" spaceflight. It's only semi-realistic, but made simpler so people can actually play it as a game. That's what I meant by my desire for a "gamers" aerodynamic package.

Well first off, I'm not talking about planes that don't fly (I mentioned that earlier). I'm talking about planes that don't fly well. I don't have any issues with the wings ripping off, I just get up to altitude and need to level off and increase speed before losing intake air and during that process I lose control. I have been able to get into orbit, but just barely and with so much fuel, there isn't enough left to de-orbit. In that case I didn't lose control, I just couldn't pull up quickly enough to take advantage of the speed I built. But that was just one case, most of the time the thing wobbles out of control and won't fly straight or I can't pull up at all beyond a certain elevation.

At the very least I have to get to 150km and have enough fuel to rendezvous.

Welcome to the wonderful world of SSTO design. There's a reason we don't have it yet.

That being said, realize that by the time you get up to 10 KM, you're running at pretty much the ceiling of what could be classified as 'normal' airplanes. Cruise altitude for commercial airliners and the like is around 35,000 feet. Which is 10,668 meters on earth. However, Kerbin's atmosphere shallower than Earth's. Kerbin's scale height is 5, Earth's is 8 and some change. Which means the Kerbin equivalent to 35,000 feet is 6,275 and some change meters.

If you're flying above that around 8 to 10 km, then you're effectively flying at U-2 or SR-71 altitudes. At that altitude, your design stops being a typical aircraft and has to start being more advanced. The atmosphere is mostly below you at that point, and your design has to be built for the fact that your control surfaces have very little to work with, so they have to be large. Above 19 km, and you're in that gray area between space, and air flight. Too high up for typical air breather engines, too low to really be 'clear' of the atmosphere. You need to get above about 35 km for that.

Edited July 1, 2014 by AdmiralTigerclaw

[R0cketC0der]

That's because KSP doesn't implement "real" spaceflight. It's only semi-realistic, but made simpler so people can actually play it as a game. That's what I meant by my desire for a "gamers" aerodynamic package.

Well first off, I'm not talking about planes that don't fly (I mentioned that earlier). I'm talking about planes that don't fly well. I don't have any issues with the wings ripping off, I just get up to altitude and need to level off and increase speed before losing intake air and during that process I lose control. I have been able to get into orbit, but just barely and with so much fuel, there isn't enough left to de-orbit. In that case I didn't lose control, I just couldn't pull up quickly enough to take advantage of the speed I built. But that was just one case, most of the time the thing wobbles out of control and won't fly straight or I can't pull up at all beyond a certain elevation.

At the very least I have to get to 150km and have enough fuel to rendezvous.

If you have your center of mass in front of your center of lift and made sure that the center of mass doesn't shift much during flight your plane should usually fly stable. If you can't pull up or down quickly, your craft either needs more control surfaces or it is too stable and you need to get the center of lift closer to the center of mass. Also don't expect even highly manueverable craft to be able to turn quickly at hypersonic speeds.

[Alshain]

Not looking to do barrel rolls here. I'm looking to pull up so I can get into space. I'm not sure what larger control surfaces I could use, but even if I did, then how would I get it off the ground without crashing. It seems to be one or the other but not both.

CoM and CoL are fine, and at the time were talking, it's not even close to empty of fuel so I'm certain DCoM is probably not an issue. In the one case I succeeded it actually stabled out once I got nose up. There's just the middle window where it's incredibly touchy. You try to pull up even a little and your turning 180 all of a sudden. I've not been able to reproduce that one success, even with the same plane.

I do have some screenshots of the one success, but I don't know that you will be able to see much (after stranding it in orbit I sent a refueling rocket so, yes it is on Minmus, but hardly single stage). This flight did have similar troubles but I was lucky enough to fight it into orbit. I'd just like to not have to fight it, which is why I was looking at stability derivatives, and that brings us back to the original problem of meaningless numbers.

Edited July 1, 2014 by Alshain

[NathanKell]

That's because KSP doesn't implement "real" spaceflight. It's only semi-realistic, but made simpler so people can actually play it as a game. That's what I meant by my desire for a "gamers" aerodynamic package.

lolwut?

Yes, exactly! That totally explains why when I burn radial+ I go up rather than changing my perigee. Oh wait.

No, KSP exactly implements orbital mechanics. The fact that it doesn't implement n-body mechanics is not because it's easier for the users, but because it's easier for SQUAD. It's perfectly realistic within a 2-body system of point gravity sources.

The fact that you've grown used to orbital mechanics should not make you think that something you *haven't* grown used to is harder, let alone more counterintuitive.

EDIT: Post pics or we're shooting in the dark here.

[Gwincraft]

Welcome to the wonderful world of SSTO design. There's a reason we don't have it yet.

That being said, realize that by the time you get up to 10 KM, you're running at pretty much the ceiling of what could be classified as 'normal' airplanes. Cruise altitude for commercial airliners and the like is around 35,000 feet. Which is 10,668 meters on earth. However, Kerbin's atmosphere shallower than Earth's. Kerbin's scale height is 5, Earth's is 8 and some change. Which means the Kerbin equivalent to 35,000 feet is 6,275 and some change meters.

If you're flying above that around 8 to 10 km, then you're effectively flying at U-2 or SR-71 altitudes. At that altitude, your design stops being a typical aircraft and has to start being more advanced. The atmosphere is mostly below you at that point, and your design has to be built for the fact that your control surfaces have very little to work with, so they have to be large. Above 19 km, and you're in that gray area between space, and air flight. Too high up for typical air breather engines, too low to really be 'clear' of the atmosphere. You need to get above about 35 km for that.

@Alshain

This 100%. Honestly look at SSTO designs that other people have put together. My first spaceplanes with FAR were terrible, and barely made it to orbit. As I got more familiar just straight up FLYING them, you get a feel for what the plane is doing when it all goes wrong. This takes time, but now I can go from a pit in an empty hanger to an cargo capable SSTO with enough fuel to do a Geokerbin orbit in a few hours. Fly some of the FAR Stock SSTO planes. Think about how they handle at various altitudes. Look at how many control surfaces they have, where their CoM and CoL are.

Personally, I'd take a look at some of Hodo's planes. Most of my superheavy spaceplane lifters are based on how some of his designs look.

Reference: http://forum.kerbalspaceprogram.com/members/80282-Hodo

[Alshain]

lolwut?

Yes, exactly! That totally explains why when I burn radial+ I go up rather than changing my perigee. Oh wait.

No, KSP exactly implements orbital mechanics. The fact that it doesn't implement n-body mechanics is not because it's easier for the users, but because it's easier for SQUAD. It's perfectly realistic within a 2-body system of point gravity sources.

The fact that you've grown used to orbital mechanics should not make you think that something you *haven't* grown used to is harder, let alone more counterintuitive.

Really? I had no idea that astronauts and cosmonauts had to ability to leave their bodies and go into a birds eye view of the solar system and draw lines on it to tell them where their burns were going to take them. Imagine that. Who developed that technology? I'd like to invest in their next project.

[Alshain]

@Alshain

This 100%. Honestly look at SSTO designs that other people have put together. My first spaceplanes with FAR were terrible, and barely made it to orbit. As I got more familiar just straight up FLYING them, you get a feel for what the plane is doing when it all goes wrong. This takes time, but now I can go from a pit in an empty hanger to an cargo capable SSTO with enough fuel to do a Geokerbin orbit in a few hours. Fly some of the FAR Stock SSTO planes. Think about how they handle at various altitudes. Look at how many control surfaces they have, where their CoM and CoL are.

Personally, I'd take a look at some of Hodo's planes. Most of my superheavy spaceplane lifters are based on how some of his designs look.

Reference: http://forum.kerbalspaceprogram.com/members/80282-Hodo

Ok, guys. Believe me I have done all this. I'm not coming here after my first attempt. I'm coming here after almost a month of trying to get a flyable plane with FAR and only one that just barely got lucky. If it's going to take a month to build one plane that barely works then it's not a game. I really all I wanted was an explanation of the stability derivatives.

[R0cketC0der]

I do have some screenshots of the one success, but I don't know that you will be able to see much (after stranding it in orbit I sent a refueling rocket so, yes it is on Minmus, but hardly single stage). This flight did have similar troubles but I was lucky enough to fight it into orbit. I'd just like to not have to fight it, which is why I was looking at stability derivatives, and that brings us back to the original problem of meaningless numbers.

http://img.photobucket.com/albums/v445/Alshain/screenshot34.png

http://img.photobucket.com/albums/v445/Alshain/screenshot31.png

The problem with this craft is that it can't pitch fast enough, right? If that's the case I'd try adding control surfaces to the canards or replacing them with winglets.

[Alshain]

The problem with this craft is that it can't pitch fast enough, right? If that's the case I'd try adding control surfaces to the canards or replacing them with winglets.

No, sorry I should have mentioned that. The problem on this one is it tends to lose control. I have fight it back and forth to keep it from flat spinning (I think or maybe just pitching out of control, not clear on that) just after leveling off. The fact this one finally made it means I was able to keep it from spinning long enough to build speed. Once I get that speed and the rapiers switch, the rest of the ascent is pretty easy but it because I'm fighting it the nose is not generally where I want it and burn too much fuel getting it into orbit. If I recall I was actually pointed almost north by the time I regained control (90 deg ascent), I was kind of surprised I saved it. I'll try winglets instead. I feel like I did that once but I've done so many things I can't remember. It's just kind of randomly saying "I wonder if this will work" at this point.

I wish I knew how to take video.

Edited July 1, 2014 by Alshain

[camlost]

Well first off, I'm not talking about planes that don't fly (I mentioned that earlier). I'm talking about planes that don't fly well.

That is not caused by FAR being too complex or your not understanding some numbers. It just means your design is not good enough, either from lack of control authority or stability etc. Most of these problem will persist even if you use stock aerodynamics, except for the CoM shifting effect. It's not wiki or FAR to blame

[jrandom]

Well first off, I'm not talking about planes that don't fly (I mentioned that earlier). I'm talking about planes that don't fly well. I don't have any issues with the wings ripping off, I just get up to altitude and need to level off and increase speed before losing intake air and during that process I lose control. I have been able to get into orbit, but just barely and with so much fuel, there isn't enough left to de-orbit. In that case I didn't lose control, I just couldn't pull up quickly enough to take advantage of the speed I built. But that was just one case, most of the time the thing wobbles out of control and won't fly straight or I can't pull up at all beyond a certain elevation.

At the very least I have to get to 150km and have enough fuel to rendezvous.

Ah! Not just any plane, but an SSTO! Got it. I'm very curious now to see your planes! If you're losing pitch control at high altitudes, your CoL might be a little too far back (at supersonic speeds the CoL moves backwards a bit towards the rear of the plane). I've also encountered this behavior when my pitch control surfaces were too few or didn't deflect enough. At very high altitudes the atmosphere doesn't work the same -- it's more of a ah... drag cloud, I guess, than something you can aerodynamically fly through. On some of my stock-sized KSP SSTOs I had to enable RCS at very high altitude to keep the thing oriented correctly.

Also, if you're not using a dry CoM marker, your CoM might be moving too far away from the CoL when the plane is low on fuel. That absolutely destroyed the reentry ability of a lot of my SSTO designs -- it would always flip around backwards so the engines aimed prograde because of the CoM shift from fuel drain.

So please, if you could, post screenshots showing CoM/CoL! We can help!

Edited July 1, 2014 by jrandom

[NathanKell]

Really? I had no idea that astronauts and cosmonauts had to ability to leave their bodies and go into a birds eye view of the solar system and draw lines on it to tell them where their burns were going to take them. Imagine that. Who developed that technology? I'd like to invest in their next project.

I'd say map view is a very poor substitute for the maneuver planning software NASA uses, but eh.

[AdmiralTigerclaw]

Ok, guys. Believe me I have done all this. I'm not coming here after my first attempt. I'm coming here after almost a month of trying to get a flyable plane with FAR and only one that just barely got lucky. If it's going to take a month to build one plane that barely works then it's not a game. I really all I wanted was an explanation of the stability derivatives.

What do you MEAN by 'flyable'?

Do you mean:

1: Getting off the runway and into the air, period.

2: Having a design that doesn't immediately try to do summersaults the moment you go gear-up.

3: Having it stay under control at high altitude.

4: Having it reach orbit.

You really need to clarify what you mean. I can slap together a perfectly stable aircraft in ten minutes and fly it around without touching the graphs. Basic subsonic aerodynamics are easy. It's not a high performance aircraft, and it's not SSTO capable, but I can do it.

Are you really complaining about the fact that you're having a hard time with SSTO and just blanket labeling a high altitude, high mach aircraft as 'barely' flyable? If that is the real problem, welcome to the club. The mod is not making anything especially nightmarish, an SSTO is just very hard to make until you know exactly what the performance constraints and flight regimes need to be, and the basic design principles you have to work with. I haven't even made one that gets above LKO yet, and I know how to read the data on all the graphs, more or less.

Like all aircraft concepts, once you know what a specific performance design looks like, building different designs for the same regime is easy. But figuring out what you need for the first time is a lot of failing. A mere month of failing is not something to be upset about.

Clockwise from left to right.

1: Supersonic high-altitude recon aircraft. Very fast, very efficient. Needs a lot of takeoff and landing speed to remain controllable. Do NOT attempt hard Gs.

2: Very gentle-flying turboprop. Can get off the runway with almost a feather-touch to the aft stick at full flaps. Controls gently, flies very reliably, almost hands off if I trim it. Very stable and settles nicely. Good plane for flight practice.

3: Supersonic bomber. Pretty good mix between 1 and 2. Goes fast when I want to, handles decent at low speeds without too much trouble. Nimble for its size.

4: Ground Attack aircraft. Turns and controls very well at low speeds, has plenty of power, and is very efficient. Not very fast for a jet, but it behaves well.

Each of these aircraft are based on the real thing, and perform in completely different 'flight regimes'. Some of them were harder to build right than others. (The A-10 analogue took six hours to work out how to get it to look like the A-10 but not attempt front flips every time I gunned the throttle.) Just remember that. (And that's KNOWING how it's supposed to look and behave.)

Also, FAR simulates the dynamic shifts for supersonic flows. I wonder if we can ever convince Ferram to come up with a tool that would render airflow regime estimates as a graphic in the hanger. Show stalls, normal flow, shocks, and supersonic flow. Knowing where those are and what shape they are would help a LOT at supersonic.

Edited July 1, 2014 by AdmiralTigerclaw

[Hodo]

I've read the wiki, it's kinda useless.

The most useless thing that could be written in a wiki. If a wiki has to say that, there might as well not even be a wiki.

The question still stands, anything that actually helps understand what they mean or how to tweak each individual one. Not "make them green", but how to make them green. I'm not an aircraft designer in real life, those numbers are meaningless and if I move one part that might change one thing to green, 3 others go red, because I don't know what they mean.

I wish someone would make a "gamers" aerodynamic mod. Something not impossible to understand unless you design aircraft for a living like FAR, and something not so stupid you can fly a box like stock. We basically have a choice of one ridiculous extreme or the other.

So you want an "EZ" mode aerodynamic model, but not the stock one? What?!

Do you want to know how I learned to understand FAR. I ate lunch for a solid year at Pope Army Airfield on Fort Bragg and watched C-130s and C-17s land and take off. I then looked at how they were responding to the inputs given at different stages of take off and landing. I then looked up videos on Youtube to see how aerodynamic forces affect wings at different speeds, yes they exist. And finally I flew a few dozen missions in Falcon 4.0 just to refresh myself on how aircraft "feel".

You know what, now I can build some amazingly stable aircraft that almost fly themselves. All it takes is to use a bit of the ol' grey matter between your ears and you can figure it out.

[Alshain]

Ah! Not just any plane, but an SSTO! Got it. I'm very curious now to see your planes! If you're losing pitch control at high altitudes, your CoL might be a little too far back (at supersonic speeds the CoL moves backwards a bit towards the rear of the plane). I've also encountered this behavior when my pitch control surfaces were too few or didn't deflect enough. At very high altitudes the atmosphere doesn't work the same -- it's more of a ah... drag cloud, I guess, than something you can aerodynamically fly through. On some of my stock-sized KSP SSTOs I had to enable RCS at very high altitude to keep the thing oriented correctly.

Also, if you're not using a dry CoM marker, your CoM might be moving too far away from the CoL when the plane is low on fuel. That absolutely destroyed the reentry ability of a lot of my SSTO designs -- it would always flip around backwards so the engines aimed prograde because of the CoM shift from fuel drain.

So please, if you could, post screenshots showing CoM/CoL! We can help!

Ok, when I get home (couple of hours) I will get screenies. But I did try moving them closer together and then I just lost control much lower and slower. That the way it always seems to go, one extreme to the other. As mentioned earlier, I don't think it's fuel as the tanks are mostly full at that point, remember I haven't even switched off of air breathing yet. I can't imagine the CoM changing significantly. This one had absolutely no issues landing, I got it on the runway and everything.

[Alshain]

So you want an "EZ" mode aerodynamic model, but not the stock one? What?!

Do you want to know how I learned to understand FAR. I ate lunch for a solid year at Pope Army Airfield on Fort Bragg and watched C-130s and C-17s land and take off. I then looked at how they were responding to the inputs given at different stages of take off and landing. I then looked up videos on Youtube to see how aerodynamic forces affect wings at different speeds, yes they exist. And finally I flew a few dozen missions in Falcon 4.0 just to refresh myself on how aircraft "feel".

You know what, now I can build some amazingly stable aircraft that almost fly themselves. All it takes is to use a bit of the ol' grey matter between your ears and you can figure it out.

Lol, You just made my point. It's a game, not a career. I was just saying I want something semi realistic but not so realistic that I have to spend years of training to do it. I don't plan of going to flight school to learn KSP, and I don't think many people that play the game would. But, more than anything, I'd just like someone to explain why the numbers are green and red.

[jrandom]

Ok, when I get home (couple of hours) I will get screenies. But I did try moving them closer together and then I just lost control much lower and slower. That the way it always seems to go, one extreme to the other.

Yep. That's plane design for you! A plane that is stable at supersonic speeds is going to be super touchy on the pitch at subsonic speeds. This is true of real aircraft. And the opposite: a plane that is stable at subsonic speeds is going to have pretty much zero pitch control when supersonic and will act like a lawn dart instead. The trick is to find that special middle ground where it's juuuust stable enough at subsonic speeds that you can fly it up to thinner atmosphere and higher speeds where the plane will be more stable. I still have to trial-and-error this but I've gotten much better at my CoM/CoL placements to give me something that has a good chance of working right out of the gate.

When I get home after work I'll take screenshots of the aircraft I posted above, but with the CoM/CoL markers activated so you can see the placement of them. That plane is pretty sensitive on the pitch control when climbing up to mach 1, but past that it flies extremely well in straight lines. Turns like a dead fish, though. It's not the best-ever design.

The reason I keep pushing for dry CoM images is that the dry CoM is not as intuitive as it sounds. I had no idea this was the case until I started using RCS BuildAid and could see it. It changed my entire approach to plane design.

Edit: I just saw some images you posted earlier and wanted to chime in on those: A plane that has lifting surfaces in the front is going to make the oversensitive pitch at subsonic speeds worse, since it'll act as a sort of feedback loop: the plane tilts back so the front surfaces generate more lift, pitching the plane up even more which then generates even more lift, etc... You have to be extremely careful with designs that have any kind of lifting surface up near the front of the plane.

Edited July 1, 2014 by jrandom

[Hodo]

Lol, You just made my point. It's a game, not a career. I was just saying I want something semi realistic but not so realistic that I have to spend years of training to do it. I don't plan of going to flight school to learn KSP, and I don't think many people that play the game would. But, more than anything, I'd just like someone to explain why the numbers are green and red.

You don't need to go to flight school. You just need to understand the basics of aerodynamic flight. Hell if a bird can do it so can you.

It isn't rocket science, no really it isn't. If it is shaped like a brick with wings, it will fly like a brick with wings. Case and point, the Space Shuttle. There are three simple rules to FAR.

1- Keep your CoL behind your CoM but not so far you cant lift your nose.

2- Keep it simple. Complex is bad.

3- Set your control surfaces. Don't do this and you will have the twitchiest worst controlled aircraft in history, right behind the F-104.

EDIT- Look at this ONE aircraft. And the FAR readings in the flight data, most importantly the Q information.

Notice the Q is over 40kpa. Which means I am experiencing pretty high airpressure over the wings. If I do something stupid like you can get away with in stock KSP, the wings will most likely fly off.

Now in this picture it is a fair bit higher, realism overhaul real Earth scaling. I am cruising at about 33kft above the ground, at Mach 2.06. If you notice the dynamic pressure is almost 50% higher then the previous picture. That is because I am going a fair bit faster. Again, if I do something stupid the wings will snap off. Just like a real aircraft.

This is why a REAL LIFE Boeing 777, can't pull out of a extremely steep dive, it will overspeed and tear its wings off.

Edited July 1, 2014 by Hodo