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

[BigNose]

That would be one hell of a story to tell if you actually get a job in the aerospace industry that way!

I study mechanical engineering myself, but I don't think my Aviation Lights mod will do me any good in that respect...

I wish you the best of luck ferram!

[StevenRS11]

I know, its super satisfying to have someone recognize something like that. I make a mod for minecraft (Is that anathema around here? I feel like it might be. Oh well.) and when my compsci graduate TA told me he had played with it, I almost died. Not quite my professor, but still. It was nice.

Dartmouth college, but he is about as non-industry as a physicist can get, and his field is all about very small things. He is definitely pure academia, haha. I don't think we offer any aerospace stuff at the undergraduate level, though I wish we did. Is it sad that I would seriously consider taking a class just to make better virtual planes? And of course understand how they actually work, instead of just parroting what I think stereotypical airplanes look like.

[camlost]

I know, its super satisfying to have someone recognize something like that. I make a mod for minecraft (Is that anathema around here? I feel like it might be. Oh well.) and when my compsci graduate TA told me he had played with it, I almost died. Not quite my professor, but still. It was nice.

Dartmouth college, but he is about as non-industry as a physicist can get, and his field is all about very small things. He is definitely pure academia, haha. I don't think we offer any aerospace stuff at the undergraduate level, though I wish we did. Is it sad that I would seriously consider taking a class just to make better virtual planes? And of course understand how they actually work, instead of just parroting what I think stereotypical airplanes look like.

https://www.edx.org/course/mitx/mitx-16-110x-flight-vehicle-aerodynamics-871

It starts tomorrow

[Starwaster]

Is it possible to setup a part so that FAR does not give it drag?

I have the B9 landing gear in mind as I say this. Technically they're radially attached parts but they're supposed to represent gear that retracts into whatever part they're attached to. So I'd like to exempt them from drag if there's any configuration I could do to them to accomplish that.

[ferram4]

Define a FARBasicDragModel but give it an area (S) of 0. Then it won't apply any drag forces to that.

[Starwaster]

Define a FARBasicDragModel but give it an area (S) of 0. Then it won't apply any drag forces to that.

Alrighty then, thanks!

[HoneyFox]

Hi ferram, currently an object spinning even in vacuum will de-spin gradually. can you implement a sub function that sets parts' rigidbodies' angularDrag according to air density or something similar?

[ferram4]

Currently FAR ends up zeroing out every affected part's AngularDrag and substitutes its own air density-based angular damping function, so that already happens. I suspect the reason that angular momentum isn't being conserved is due to some amount of numerical errors in the physics engine, and there's really not much I can do there.

[rhoark]

Compression lift still isn't modeled, right? Maybe there's a good-enough treatment without doing full CFD: set an angle based on speed and nosecone diameter, then within that angle magnify the effect of any anhedral or ventral fence.

[NoMrBond]

Is there a way to get FAR to recognise fairings, shrouds and or bays which should be protecting their payloads without changing the name= arguments to include one of the recognised terms?

Like a providesSheilding = True or could it scan the 'description =' argument as well as the 'name ='

I'd like to have some bays and their doors provide the appropriate FAR protections but I'm having no luck thus far and I'd prefer to avoid changing the names of the parts as this would break compatibility

[ferram4]

It's only the title of the part that has to change, not the name. You don't break compatibility by changing the title.

Adding another flag to the part isn't that simple, since it would basically require defining all of the drag parameters right then and there in the config file for it to work properly. That, or lots and lots of code refactorings to allow you to define only some of the drag parameters without FAR overriding those when it calculates the other parameters.

[NoMrBond]

Ah, great, thanks. I thought it was the name= argument after reading the OP for some reason, now I feel silly.

Is there a list of keywords (importance of spelling) which FAR recognises beyond 'cargo bay', 'nose cone' and 'fairing', such as 'shroud' or 'fuselage'?

[ferram4]

Check in the config.xml. You can add more if you like, but that can cause strange behavior if you get a false positive.

[NoMrBond]

Thanks again

I'll avoid adding more terms on my own config though, as that would mean the parts wouldn't work for anyone else, better to make them work with stock FAR than to forment annoying incompatibilities

[palker]

RSS+FAR+Deadly reentry+9000m/s deltav ICBM = Really big numbers. Just look at this almost 8 megapascals of dynamic pressure and 550 kN of drag lol. Also i do not know why but once the warhead hits the really dense atmosphere it starts twitching like crazy. I modified the FASA nuke warhead to survive even steepest reentry and it actually managed to wobble itself back to ballistic trajectory out of atmosphere it looked pretty funny actually. I guess at that high speed and high air density computer just cannot handle the ridiculous forces and freaks out or something.

[ferram4]

That's just the physics simulation using too high a timestep for the forces involved and the rate that they're changing. There's nothing I can do to fix that, since that part of the physics simulation is out of my hands.

[MAKC]

Is there a way to view the total amount of drag forces (in kN) acting on a craft?

[palker]

That's just the physics simulation using too high a timestep for the forces involved and the rate that they're changing. There's nothing I can do to fix that, since that part of the physics simulation is out of my hands.

Yeah i thought that would be something like that. Time to try out that time control plugin that i heard about.

[bs1110101]

Does anyone have a FAR config for these grid fins? forum.kerbalspaceprogram.com/threads/66502-Kerbonov-Kn-2-Cockpit-Module Can FAR even work with grid fins, or can it only work with aerodynamic surfaces all aligned on the same plane?

[ferram4]

Grid fins could probably be approximated using FAR's current wing model, but I'd have to look up if there's any easy way to do it. Honestly, it should have a lightly different definition than a standard lifting surface, but I'm not sure if it's worth coding up an extension of the current model for a single part.

[celem]

Is there a way to view the total amount of drag forces (in kN) acting on a craft?

While I dont think that data is available summed up as kN you can get a general idea for design comparisons through the 'BC' attribute which is measured in kg/m2. It stands for Ballistic Coefficient and is factoring in mass, frontal-area and then overall shape and streamlining to describe how effective the craft is at splitting the air. You can find it in the flight data FAR panel, iirc its the very bottom attribute.

[bs1110101]

Grid fins could probably be approximated using FAR's current wing model, but I'd have to look up if there's any easy way to do it. Honestly, it should have a lightly different definition than a standard lifting surface, but I'm not sure if it's worth coding up an extension of the current model for a single part.

Well, i'm fine with that, can you at least make a very approximate patch so i can use them, right now i'm just using the data copy-pasted over from one of the bigger winglets from B9 and it seems totally unrealistic.

[bulletrhli]

Hey Ferram, are we going to see an update or a experimental release anytime soon?

[Guest]

Would that be possible to add an option of having a control surface deflect further in one direction than in the other? Elevons on Space Shuttle, for example, could deflect 40 degrees upward and 25 degrees downward. I can see it being useful for when the aircraft has nose-down problems.

[ANWRocketMan]

@ferram4: How can I determine what speed a re-entry vehicle will have as it descends from a certain altitude through an atmosphere? I can do the orbital mathematics myself but the aerodynamics is not my strong suit.

I want to determine how much dV my retro-rockets should have to slow me down to a desire-able speed for example at a certain altitude and speed. The only way I can do this now is to actually fly the craft out there and test it but that takes a lot of time and effort to design a ship with almost the correct characteristics but is not the final product.