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

[cpx]

I have to say stock aerodynamics went not that FAR.

[Van Disaster]

Does camber of wings help increase lift with FAR? Because I really want to increase lift for my aircraft. They need to land at speeds around 230 kph, and even then they are unstable. And is there any way to solve the flaps-causing-stall issue? I can't make flaps, or any high-lift devices for that matter, work over 12 degrees of deflection reliably. Every time I have flaps open and I pitch up the slightest bit, they stall and I need to nose down really far to stick the airflow back on to the top.

(In addition, but this is less of a problem, flaps under the wing cause a stall. See the Messerschmitt Me 163 "Komet" for an example. Its flaps are mounted under the wings.)

Has anyone managed to make flaps work at high degrees of deflection (45-60 degrees preferably, but anything at all helps)? I know that to make the flaps bigger would make more lift even if AoA stayed the same... but I want to find how to increase lift through increasing AoA without causing a stall.

Don't forget there's levels of stall - you might find some UI element is complaining you've got a stalled surface when it's only 1% stalled & not really a problem.

What is a problem is a surface stalling will stall the one behind it, but that's got simple design solutions.

[UnanimousCoward]

I have to say stock aerodynamics went not that FAR.

*Rimshot*

Dude, should've followed that up with "Thank you! I'm here all week. Remember to tip your waitress!"

[Insanitic]

The thing I like about FAR is simply because it gives me hard and true facts and statistics about the aerodynamics of my vehicle, something that the stock model does not have yet. So I'm still gonna use FAR over stock definitely.

[LORDPrometheus]

Yeah plus using FAR prevents having to learn a new building style for the stock aerodynamics

[Jovus]

*Rimshot*

Dude, should've followed that up with "Thank you! I'm here all week. Remember to tip your waitress!"

Tried stock aerodynamics. I appreciate it. (I mean that in a real way, not just 'cause we can turn it off - though that's awesome.) However, I'm just too FAR along to go back now.

[Patupi]

Tried stock aerodynamics. I appreciate it. (I mean that in a real way, not just 'cause we can turn it off - though that's awesome.) However, I'm just too FAR along to go back now.

*Badum TISH!*

And don't worry, the kerbonauts won't throw rotten tomatoes anywhere NEAR you. They don't grow on Kerbin (though I won't say what they WILL throw EWWW!)

[Hodo]

Yep I can say the same, tried the new aerodynamics, they are a GREAT improvement over the old but I will stick with FAR.

[John FX]

One thing that makes me happy is that stock users will now make craft that will probably fly OK in FAR. They will have heatshields so they might work in DRE etc

I'm looking forward to seeing nu-FAR...

[kcs123]

Squad servers have been overloaded all day, could not download 1.0 until now. I'm curious how stock aero behave now, probably give it a try only for few days until FAR is updated.

Stock aero could be a good choice for noobs to game, but all of us that have used to FAR simply could not play this game without it.

Thanks ferram for making it and keeping this mod updated.

[ferram4]

I will say that nuFAR is awesome and should be out in a day or two. Currently I'm waiting on a stripped-down parachute module from stupid_chris (who was gracious enough to offer one) to replace stock behavior. For obvious reasons, I can't release a FAR version that results in pods impacting the ground at 180 m/s. Also, I'm too sleepy to make a good judgment call about its release state.

For those wondering exactly what nuFAR / voxelFAR / vesselCenteredFAR does compared to previous versions, it basically does away with the part-centered operation of the previous FAR versions (the same behavior that powers NEAR and newStock) in favor of a vessel-centered approach. Instead of the part-centered complications of determining the interactions between parts (which are never done exactly right) it'll create a voxel model of the vehicle to work with, like these guys:

From this, I can get a lot of data about how the vessel will behave in flight. Most importantly, I can implement a long-awaited feature: area-ruling. Basically, it's a requirement for transonic and supersonic flight that states that for minimum drag, a vehicle's cross-section must vary smoothly. And very small changes in cross-section can have a surprisingly large effect on transonic and supersonic drag. So for ease of use, you'll get a nice graph of cross-sectional area over the vehicle so you can see where to mess with things:

The yellow line is the 2nd derivative of cross-sectional area, which actually goes into the math behind drag. Green is obviously cross-sectional area. Transonic area ruling consists of fiddling with the cross-section curves until you smooth out the curve to get minimum drag. For obvious reasons, some people will find this unfun given the limited design choices we have for shaping things, so there are difficulty options that include various multipliers to the total drag and smoothing functions for the area to deal with the noisiness of the voxel model itself. But to give you an idea of how this makes things go, getting supersonic is an exercise in flying through a brick wall that may tear you to shreds. I've actually had to throttle down near Max Q to prevent a very nasty, very large rocket from coming apart and destroying itself.

Besides that fun, the voxel approach also allows better resolution of body lift, which can give bodies their proper forces, rather than a simpler approximation from parts. Another benefit of the voxel approach is that cargo bays and payload fairings are emergent from the system. Rather than being defined top-down like in FAR, NEAR, or newStock, any collection of parts in a hollow arrangement will be tried as shielded from the airflow. Although the current wing model is the legacy oldFAR wing model, I also expect that the voxel approach can be used to calculate wing shapes and provide a much more accurate model of the wings as well as the fuselage.

So, yeah. Enjoy newStock for now or stay on 0.90 and keep oldFAR. nuFAR will be out soon, when I will battle the demons of what version to give it.

[Enceos]

Even though I understood only half of the said, I'm so hyped to see it in action! The voxel approach is a magnificent idea.

Edited April 27, 2015 by Enceos

[AndreyATGB]

I love you, seriously your mod is easily one of the best for this game.

[tetryds]

Even though I understood only half of the said, I'm so hyped to see it in action! The voxel approach is a magnificent idea.

Let me simplify it for you:

"I will say that nuFAR is awesome" - ferram4

When you make an airplane, the actual shape matters a lot for transsonic drag.

The effects are huge, you can see area ruling traits on every airplane.

Now, FAR will be able to define the actual craft shape.

That means that you can half-clip parts and you will actually have only the external area affecting it.

That also means no more antennas covering nodes for parts inside the fuselage, nor cheating by covering nodes.

And much more.

So yeah, it is amazing.

Already working on the new FAR Colibri, gonna be badass :3

Edited April 27, 2015 by tetryds

[Surefoot]

So for ease of use, you'll get a nice graph of cross-sectional area over the vehicle so you can see where to mess with things:

Yay. Nerdgasm. That is really, really neat, like playing with tools before only available to high tech labs. Sir, you rock.

I've actually had to throttle down near Max Q to prevent a very nasty, very large rocket from coming apart and destroying itself.

Sounds like a lot of fun. On the plus side it will promote designs that work in real world, will it Like, full delta wings with elevons ?

Besides that fun, the voxel approach also allows better resolution of body lift, which can give bodies their proper forces,

That means proper lifting bodies, sounds neat for re entry vehicles. You just added a few hundreds hours of KSP fun here

Although the current wing model is the legacy oldFAR wing model, I also expect that the voxel approach can be used to calculate wing shapes and provide a much more accurate model of the wings as well as the fuselage.

Means wings composed of multiple parts (as a limitation of the game engine) will behave as a whole, with proper camber and such .. hmmmm and will they be computed as part of the lifting body, with vortices and so on, so for instance side chines would become truly useful..

Very exciting.

[NoPersona]

Just one question about nuFAR. Will the new approach allow you to model dynamically changing wing shapes, for example, like using Infernal Robotics to fold the wing back? Or will the voxel model only be calculated at certain times like loading/launching/staging?

[tetryds]

I forgot to mention that making fairings out of any part is going to work, even wings.

But for wings you need to make sure that the fairing is closed.

[Dinokin]

nuFAR...

dude you're awesome!

[Instresu]

Sorry guys if I'm late, but will there be a working version for FAR in KSP 1.0?

[Autochton]

Now we need a fuselage part mode that allows us to create custom, smooth shapes. Perhaps by setting cross-sections at certain points and interpolating between those. I keep considering what some actual smooth-shaping tools might work like, because even if you go back to WWII, the fuselages weren't straight cylinders.

Makes me wish I could find enough time to mod KSP. I consistently can't even find time to develop the games I want to make on my own.

[ThorBeorn]

KSP is probably the best game I've ever played and 1.0 is its greatest update so far imo. Yet I feel much more excited about nuFAR. All those fuselages that shall be created, area ruling, better lifting bodies - total nerdgasm indeed

[LORDPrometheus]

so do the new changes allow aerodynamic updates without a staging event? thereby allowing proper air brakes and variable angle wings?!!!

[Crzyrndm]

so do the new changes allow aerodynamic updates without a staging event? thereby allowing proper air brakes and variable angle wings?!!!

Deploying landing gear was enough to knock one of my planes from the sky in nuFAR (it was going slow and already particularly unstable...), so yes I imagine so

[DaMichel]

For those wondering exactly what nuFAR / voxelFAR / vesselCenteredFAR does compared to previous versions, it basically does away with the part-centered operation of the previous FAR versions (the same behavior that powers NEAR and newStock) in favor of a vessel-centered approach. Instead of the part-centered complications of determining the interactions between parts (which are never done exactly right) it'll create a voxel model of the vehicle to work with, like these guys:

I love you, too! Seriously, this looks great. Please allow me to ask, how do you deal with memory requirements? If someone built a crazy whackjobian rocket, you'd certainly need an aweful lot of voxels. With the limited amount of memory available this might not end well.

Also what model do you use to obtain the aerodynamic forces? Is it the vortex lattice method?

Cheers,

Michael

[ferram4]

Aerodynamic updates have always happened without staging events. Deploying landing gear and dynamically sweeping wings have always worked in oldFAR, I don't know where you got the idea that they didn't.

The voxel resolution is relative to the total vehicle size. As a vehicle gets larger, the smaller parts of it really don't need to be resolved as finely, so it works out to approximately a constant memory load per vehicle. Also, I don't need to store the entire voxel for the entire time the vessel exists; I can convert it into an aero forces and orientations format that is much simpler to store and calculate from.

It uses newtonian impact theory for hypersonic drag, an implementation of slender body theory for transonic drag, and an empirical function for subsonic. That's for 0 AoA; for off-0 AoA forces I use a combination of potential flow lift (also slender body approximation) and a viscous crossflow term. It's much faster than a vortex lattice method and handles viscous effects, and in the situations where the model isn't exactly right, it tends to overpredict the forces and generally sets the requirement that people follow the assumptions of the model if they don't want it to explode in flight.

Edited April 27, 2015 by ferram4