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

[blu3wolf]

In fairness, this is due to stock drag being unreasonable, so thats hardly an issue.

[Qwits]

On 22/07/2016 at 2:09 PM, blu3wolf said:

In fairness, this is due to stock drag being unreasonable, so thats hardly an issue.

Reasonable or not, it doesn't result in supersonic turbofan cargo planes gliding across continents without slowing down, or turbojets exploding from reaching M3 at ground level like FAR stock drag does, and this is all that matters to an end-user like me. I'm not interested in exact numbers as much as I'm interested in the effect they have on game-play.

Edited July 24, 2016 by Qwits

[tetryds]

@Qwits so, if you use engines balanced for the stock atmosphere on FAR, which is meant to simulate it as realistically as possible, it will surely not work.

Stock atmosphere has much higher drag, and because of that the engines made for stock aerodynamics are a lot stronger than they should be.

FAR is not meant to be used alone, if you add AJE to your mods list and use only the engines ported to AJE you will have a much better experience.

About gliding for long distances, that is also a stock problem, stock parts are way too heavy, and that interferes a lot with the aircraft behavior.

Instead of trying to pick a mod that is meant to be realistic and dumb it down, it's highly suggested that you do the opposite, and use other mods to balance your game.

If you seek for support on that everybody will be willing to help you, but if you continue trying to change FAR to fit your expectations all I can say is that you are on your own.

[hippomormor]

Just updated to 1.1.3.

How much would i get stabbed for mentioning the TweakScale bug? Still getting lift when going under 100% scale.. I know.. It must be extremely annoying! Sorry! :/

It worked so nicely in 1.1.2 after you fixed it! 

And again thanks for being awesome with the aeronautics!

Edited July 25, 2016 by hippomormor

[MachTurtle]

Greetings everyone!

I'm working on redirecting a class E asteroid into LKO and have observed that my tug (pusher, actually) is subject to shock heating even though it's on the "shielded" side of the asteroid. I has assumed that the asteroid body would act as a heat shield during aerobraking, but that doesn't seem to be true in this instance.  Is this a result of using FAR or is it due to more fundamental KSP physics? Thanks in advance for any guidance you seasoned users can offer!

[Qwits]

On 24/07/2016 at 10:41 AM, tetryds said:

@Qwits so, if you use engines balanced for the stock atmosphere on FAR, which is meant to simulate it as realistically as possible, it will surely not work.

Stock atmosphere has much higher drag, and because of that the engines made for stock aerodynamics are a lot stronger than they should be.

FAR is not meant to be used alone, if you add AJE to your mods list and use only the engines ported to AJE you will have a much better experience.

About gliding for long distances, that is also a stock problem, stock parts are way too heavy, and that interferes a lot with the aircraft behavior.

Instead of trying to pick a mod that is meant to be realistic and dumb it down, it's highly suggested that you do the opposite, and use other mods to balance your game.

If you seek for support on that everybody will be willing to help you, but if you continue trying to change FAR to fit your expectations all I can say is that you are on your own.

Oh wow, thank you kind sir Mr. @tetryds. I sincerely appreciate your telling me that because you don't agree with the way I want to play the game, this means I won't get any help or support here. I now understand that the only way to play this game with this mod is the way you play it, and also that your view represents the view of the whole KSP community.

Your suggestion that I try the AJE modification that I already have installed is also very valuable to me considering the fact that it's with this modification installed that Mk.1 planes blow up at M3 ASL – in stock they merely do so at 50% thrust which is incidentally the 130kN that, doubled, propel a real-life F-15 at best to Mach 1.2 ASL.

I bow down at your absolutely rational and not at all logic-defying zeal to rebalance the totality of the game, including all other affected mods, to fit one single modification instead of tweaking one single modification to fit the totality of the game. If I may be so bold as to ask you for the mod you've used to reach this perfectly justified and noble goal?

I am deeply sorry for asking if the drag scaling setting already included with the FAR modification not working as I expect is intentional or a bug, and asking whether I understand its purpose correctly. There is no doubt that fixing that setting, or if I misunderstand it, providing such a setting would catastrophically dumb down the modification. Absolutely nobody should be allowed to tweak the drag value to their own liking – I now see how preposterous my idea was.

I hope my late epiphany atones for my previous sinful postings and averts your righteous indignation. Thank you again, dear @tetryds, for setting me on the only correct path that exists for a user of this excellent mod – your own path.

 

[blu3wolf]

5 hours ago, Qwits said:

I bow down at your absolutely rational and not at all logic-defying zeal to rebalance the totality of the game, including all other affected mods, to fit one single modification instead of tweaking one single modification to fit the totality of the game. If I may be so bold as to ask you for the mod you've used to reach this perfectly justified and noble goal?

Its called RO.

Its worth pointing out that its not so much about rebalancing the game to fit FAR, but rebalancing the game to fit RL.

You want to make the drag term bigger? Its 0.5 * p * v^2 * Cd * A, so you have some options there for making it bigger. You want to make it bigger independent of v, so we leave that alone. You likely want it bigger independent of A, so we leave that alone. That leaves our Cd and p. Increasing viscosity would mean increasing Cd, so that will work. Your issue I suspect is that you want more drag without more lift.

Leaving that can of crazy alone, I wonder if AJE might end up making a F110-GE-129 engine at some point? If AFBW lived up to its name, one could see about making a flyable F-16 in KSP. That would be something!

[Qwits]

1 hour ago, blu3wolf said:

Its called RO.

Its worth pointing out that its not so much about rebalancing the game to fit FAR, but rebalancing the game to fit RL.

You want to make the drag term bigger? Its 0.5 * p * v^2 * Cd * A, so you have some options there for making it bigger. You want to make it bigger independent of v, so we leave that alone. You likely want it bigger independent of A, so we leave that alone. That leaves our Cd and p. Increasing viscosity would mean increasing Cd, so that will work. Your issue I suspect is that you want more drag without more lift.

Leaving that can of crazy alone, I wonder if AJE might end up making a F110-GE-129 engine at some point? If AFBW lived up to its name, one could see about making a flyable F-16 in KSP. That would be something!

I know about RO, but changing the entire game is not what I'm after (or is there some particular part of it that only tweaks all the masses, a mega-SMURFF?). Modifying viscosity has other effects besides increasing drag and as I have previously said, those effects become too intrusive at values of 0.01 and higher – I suspect flow separation just stops existing. Ideally I'd like to see two independent Cd and Cl multipliers because with stock masses and wing sizes there's a very obvious lack of lift. I could live with a common L/D multiplier. In either case, I feel like giving the user the ability to adjust these values to their particular installation and gameplay preferences would greatly increase the popularity of this mod. There's no reason it should limit the user to total realism – only a tiny fraction of the player base is interested in it.

What to me is still left unanswered is: isn't the already existing setting supposed to do just that?

Edited July 26, 2016 by Qwits

[cantab]

"Lack of lift", at subsonic speeds at least, might be because IIRC FAR assumes a supersonic-type airfoil, and hasn't added the option to choose airfoils yet. Also the default wing strength value is overkill for most purposes, knocking it down to 0.5 or below will save a chunk of weight.

[Qwits]

30 minutes ago, cantab said:

"Lack of lift", at subsonic speeds at least, might be because IIRC FAR assumes a supersonic-type airfoil, and hasn't added the option to choose airfoils yet. Also the default wing strength value is overkill for most purposes, knocking it down to 0.5 or below will save a chunk of weight.

I don't think that's the issue. Modern fighters all have supersonic airfoils which doesn't prevent them from having an under-300 km/h take-off speed. In FAR, it's twice that. As for the weight, the wings contribute too small a portion of it to make a difference. Besides, that strength comes in handy to keep your plane in one piece given that it flies at 2 times the speed it should and pulls as much G as your control authority allows (you aren't safe even when using a mod such as Dynamic Controls).

Edited July 26, 2016 by Qwits

[blu3wolf]

With FAR, you can have takeoff speeds lower than that, too. Takeoff speed is related to L/W, and most parts in KSP are pretty heavy...

I see no issue with FAR being intended only for realistic use. Suggesting it should cater to more users sounds like an offer to make your own mod that does so.

[Qwits]

3 hours ago, blu3wolf said:

With FAR, you can have takeoff speeds lower than that, too. Takeoff speed is related to L/W, and most parts in KSP are pretty heavy...

I see no issue with FAR being intended only for realistic use. Suggesting it should cater to more users sounds like an offer to make your own mod that does so.

I wouldn't normally make this kind of post, however I want to illustrate to you that not only are you being unhelpful, you're outright sticking your personal opinion into my face for personal gratification.

If my suggestion sounds this way to you, you're discussing the wrong mod and should probably go and make your own mod that's intended only for realistic use, because the mod discussed in this thread is supposed to cater to more users by giving them the option to scale drag, change the leniency of area ruling, disable aero damage or turn their atmosphere into soup through cranking up viscosity. I'm here to report the first of these options not having the intended effect – I'm here to report a bug. I'm not here to have people being dicks to me, so if you don't mind freeing yourself from this burden.

Edited July 27, 2016 by Qwits

[tetryds]

1 hour ago, Qwits said:

If my suggestion sounds this way to you, you're discussing the wrong mod and should probably go and make your own mod that's intended only for realistic use, because the mod discussed in this thread is supposed to cater to more users by giving them the option to scale drag, change the leniency of area ruling, disable aero damage or turn their atmosphere into soup through cranking up viscosity. I'm here to report the first of these options not having the intended effect – I'm here to report a bug. I'm not here to have people being dicks to me, so if you don't mind freeing yourself from this burden.

That was exactly my point, I don't intend to offend you but according to @ferram4 himself, FAR is not supposed to have a wide userbase and allow people to change it as they wish, it's only made public so that he can find and fix bugs to make the mod better for himself, the other options are just conveniences that were added because he was kind enough to do it.

FAR was in fact made to be used with other realism mods and what I meant is that you will have support if you use them, but you won't have any kind of support if you change these settings and have issues.

Now your bug report is what really matters, but more info on that is required so that it can possibly fixed in the future if ferram finds it worthy. It could even be some legacy feature that was removed.

We are not attacking you in any way.

And please be polite on the forums.

Edit: and if you find a behavior unrealistic, I can ensure you that it will receive maximum priority if enough data is provided (what it is vs what it should be), as long as everything perfectly matches and FAR itself is the only difference between FAR and real life.

NathanKell tried it once and I can tell you it's really hard. He also found that drag was a bit too high for sub mach .3 speeds.

Edit2: takeoff speeds are wrong due to the lack of ground effect which may be added with the wing overhaul.

[Phineas Freak]

@WildLynx do you have a Protractor part included in your ship(s)?

[Phineas Freak]

In that case, could you test the vehicle that includes it with and without the Protactor part? The problem should be there even if you just get it out to the launch pad/runway/

Edited July 27, 2016 by Phineas Freak

[Phineas Freak]

The Protractor module by itself is fine but the actual part has a MeshCollider that is not supported by Unity 5 (and in turn by KSP) anymore. This is causing a ton of log spam, both by KSP and FAR (since FAR uses the colliders for voxelization and it fails to do so).

[ferram4]

@Qwits: There is no universal drag scaling setting within FAR.  Especially not one that will affect subsonic flight.  The only one that exists is solely for the sensitivity of the Mach 1 wave drag calculations, and that's only because the stock game's parts alone are too difficult to easily shape into the ideal shapes, so there is some leniency by default to account for the idea of, "this is close, but in reality it's shaped better than this."  If you aren't noticing any changes to drag at Mach 1, then apparently your craft have very low wave drag overall if you can fly at Mach 1 and not notice any changes.  The viscosity settings are only there because the stock game lacks values for viscosity for each of the planets and is only relevant for heat transfer and skin friction drag.  Outside that, there are no other drag settings and never will be.  I don't particularly care about popularity and considering the effect that too many users tends to have on the usefulness of bug reports I actually think it's a bad thing.

As for "lack of lift," there isn't for the shapes that exist.  FAR assumes symmetrical airfoils, based roughly on a somewhat rough-surfaced NACA 64010 for subsonic flight, but with a rather higher maximum lift coefficient of 1.6 rather than the realistic 1.2 (which technically should be even lower because roughness decreases max lift).  Any problems actually getting planes to take off with that at low speeds are almost inevitably a case of, "not enough flaps," "not enough slats," "too much weight with not enough wing," or "not enough rotation on the runway."  Hell, there's an example FAR plane (the Firehound) that lifts off the ground at 60 m/s if you really want to; it's sluggish as hell, but it does.

@MachTurtle: If it's close behind the asteroid it should, to some extent.  Conduction will still matter.  If it's too far back, it will get heating anyway because the flow will have time to come back together behind the asteroid.  That's actually stock behavior, not FAR though.

@WildLynx & @Phineas Freak: Well unfortunately I don't exactly have the means to determine when a mesh is completely broken.  People need to update their stuff, I can't exactly do it for them.

[Phineas Freak]

@ferram4 yep, that's completely understandable and we are dealing with a really old mod that has not been updated.

@WildLynx if you still get the error then i would strongly suggest to remove the part so that it won't be included by any future craft and use a Module Manager patch to add it to the command/probe modules.

[Van Disaster]

No ground effect in current FAR, that will also make takeoff feel like you're up a mountain - for the first couple of metres upwards anyway.  Allowing for slightly higher TO/lanďing speed, I've always found plenty of lift with a sensible wing loading.

[Qwits]

@ferram4 I see – the symmetrical airfoil explains much of it. Can you explain in more detail which calculations the "Frac Mach 1 Drag" setting affects and what are its values for the lowest and highest preset? Also, would you have any pointers for someone like me who would like to play with the lift/drag calculations in the source code?

Am I right in assuming that vortex lift isn't modelled either, which results in the notoriously abrupt stall when exceeding critical AOA, or is there any other reason for it?

[MachTurtle]

18 hours ago, ferram4 said:

@MachTurtle If it's close behind the asteroid it should, to some extent.  Conduction will still matter.  If it's too far back, it will get heating anyway because the flow will have time to come back together behind the asteroid.  That's actually stock behavior, not FAR though.

Thanks for the response, ferram4... I'd figured this was a KSP behavior, but it's nice to hear it from someone with firsthand knowledge. I'm attaching a couple of images just for fun. They're from a hyperbolic entry with a perigee of 52km at around 3200 m/s. In your opinion, should heat shielding by asteroids be addressed in a future KSP version?  Is there any chance a modder with particular skills in aerodynamics might fix this outside of stock?    Thanks for creating FAR... I'm able to hand-fly (no SAS, no A/P) my most recent SSTO through its entire flight regime... and it "feels" very real to this 500 hour pilot.

Edited July 28, 2016 by MachTurtle
fixed imgur link

[RageMode]

I've played with FAR pretty much since I started playing KSP back in the 0.23 days. I took a break for a while. Now coming back, using FAR, my rockets seem to be stuck on stupid. The main problem I'm having is that my rockets want to flip retrograde in the upper (~20km) atmosphere for some reason. I'm designing my rockets in a similar way to how I designed them previously. I also noticed the drag when watching the FAR flight data window seems to get up to the 20Kn range pretty quickly. Is this normal? I also notice the side forces are about equal to the drag, even when the rocket is going straight up. The way things are working right now, this is less fun realism, and more of a headache than anything else, making my rockets feel as though I have no control over them unless they have fins until they're completely out of the atmosphere, which adds a design requirement that I'm not too fond of at all. Perhaps it's a bug, or a problem with my current install. I hope that's the case at least. I've tried KSP with only FAR installed and no other mods, to make sure it's not a mod conflict, and the issue is still present.

 

I generally put fins on the bottom stage, and sometimes a smaller fin on upper stages depending on the length of the rocket and the profile. In this case, my rocket is a two stage rocket, and it seems as soon as there aren't any fins left, even in the upper atmosphere, the rocket goes retrograde no matter what I do. Gimballing engines can't counter it like I expect them to.

 

Is anyone able to provide an ideal ascent profile as far as what speeds you should be reaching at what altitude? Also, has anyone managed to launch a rocket without any fins? If FAR is supposed to be realistic, I would imagine this is possible considering the Falcon 9 has no fins, and that's a real rocket.

[ferram4]

@Qwits: Frac Max 1 Drag only affects the linearized wave drag calculation that is used for Mach 1 and a few of the values above it; at the lowest, it is 0.7, at the highest, it is 1.

For adjusting lift/drag in the source code, you'll have a lot of trouble doing that.  The wing code is set to be overhauled and replaced anyway, and although the symmetrical airfoil is assumed otherwise the lift slope for wings is overly optimistic.  Often ends up way too close to the value for a pure airfoil.

Vortex lift is not modeled because the current wing model cannot properly determine where the leading edge separation vortices should go on highly swept wings (accounting for the mess of vortex breakdown and what happens on double-deltas, inverted deltas, etc.).  Otherwise, the sudden stall is appropriate for a thinner symmetrical airfoil, especially one with as tight a nose radius as the 6A series.

@MachTurtle: I try to avoid touching as many stock things as I can because whenever I do it results in numerous new bugs for me to chase down and fix.  Since this behavior is handled by stock, and trying to fix it is an invitation to disaster, I won't.  Besides, for something like that it should already be handled correctly by stock, so... bug report time for the devs.

@RageMode: 20 kN of drag without the size of the rocket involved or the speed you're going doesn't actually tell me anything.  Honestly that sounds like an incredibly low amount of drag unless you're getting it on a tiny rocket under 100 m/s.  Honestly, that sounds like an incredibly streamlined, low-drag rocket to me.  If your side forces are equal to your drag forces, then you aren't going straight up; probably not much angle of attack going on, but you aren't going straight up.  Or your rocket is deliberately non-symmetrical, in which case, make it symmetrical.

Most of my rocket designs haven't bothered with fins, but they involve lots of engine gimballing, an initial TWR of somewhere between 1.2 and 1.6, no higher, and a pitchover around 100 m/s and then I stick to prograde as much as possible.  Moving off prograde for any reason is silly.  Spending any significant time coasting between staging is also bad within the atmosphere, because the way Kerbin is set up it aero affects staging far more than on Earth, where staging doesn't happen until aerodynamic forces don't exist anymore (heat does though, but that's different).

If your flipping happens exclusively in the upper atmosphere, and only ever when you move off prograde... stop moving off prograde.  Seriously, body lift is a strong and powerful thing, wait until your dynamic pressure has dropped more.

[RageMode]

@ferram4 My rocket is symmetrical (I'm OCD about that, even when it doesn't matter). It's a fairly small rocket, 1.25m diameter tanks. I'm using fairings. In this case, it was to launch a small probe. The first stage got me up to about 5km or so. Then upon staging, my rocket would instantly lose its balance and flip over, and aerodynamic stresses would take over and wreck the craft. I also started with a TWR of 1.3 or so. I've played RSS/RO/RP-0 before and know how to properly design a rocket. I follow pretty much the same methods you listed. But for some reason, rockets seem extremely tippy. I've since managed to get some rockets to launch. I've found the method that works best was keeping the first stage long burning (which is hard to do with my current mods and the current progression I'm at). For the record, I'm not currently playing RO/RSS. I had no problems in RO/RSS though, nothing like what I'm experiencing now, and that has FAR, too. Although I understand that's probably because of the largely different atmosphere setup and massive differences in general. I don't doubt that 20Kn of drag isn't big, I mentioned it to make sure though. For comparison, I don't think any of the engines I was using for that particular rocket were over 100Kn of thrust. I think a large chunk of the issue was that I was flying the rockets like I would in RO/RSS, and that particular design got my rocket up to 250m/s or so before 5km of altitude, which I think is too much. I notice a significant difference in flight characteristics when I got the rocket to stay around 100-150m/s under 15-20km.

 

I think it's just a case of significant changes in FAR since the last time I played KSP that made designing rockets a lot more challenging. Last time I played, it tended to make rockets easier to get into orbit, but made planes a lot more challenging than stock. After reading around a bit, it seems the NuFAR update changed things a lot, and now rockets are much harder to get stable.

Edited July 30, 2016 by RageMode

[LordOfMinecraft99]

Hi, i have a problem whenever i am playing with R.O/F.A.R. In the SPH it says the wings (all the wings, both stock and modded) dont have and lift values and they act as though the wings are just structural parts, Second, out on the runway, the wings don't provide any lift.