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

[tetryds]

The green and yellow lines/graphs, are they actually seen in the SPH or have you guys used ms paint?

- Sam

We extracted the models to blender, then ran a custom plugin to plot the lines and fitted it on the screenshot.

Nah, FAR Transonic Design cross section area analysis does this, I know that it looks like it was made on paint but it's not.

I start to smell release, anyone?

Edit: aw, Hodo killed my joke.

Anyway, doing what I mentioned above would be an interesting way to see how good the voxelization approximation is, just make sure to smoothen everything first.

[dervd123]

Any chance we'll see ground effect lift at some point?

It could be really interesting as a landing mode for large spaceships, ie. have just enough lift to pull out of a suicide dive close to the water when the ground effect starts to matter, apply airbrakes and soft land as a boat, take off with lifting body and then return to space with >1 TWR.

Basically a lifting body spaceplane that only has enough lift within a few dozens of meters of the surface and then has to transition to acting more like a rocket really low.

[Veskenapper]

I've been playing around with the dev builds, trying to figure out supersonics, and yesterday I hacked together an open cockpit jet to test something out.

Now, I got a nice, flat-ish yellow line which made this thing surprisingly stable supersonic when flying it on remote control. However, adding a kerbal - and his helmet sticking out and messing up the profile - turned the whole thing into a supersonic wobblesausage.

So first off, I find it amazingly cool that even the kerbals themselves are apparently taken into account when determining voxel placement. However - shouldn't a big gaping empty hole in the top of the plane negatively affect its flight characteristics?

[cantab]

On wing strength, should the default not be whatever makes the mass the same as in stock? That seems as good a point as any.

[sam.johnson841]

*sniff; sniff* Nope all i can smell is burnt Val from my latest, "experiments". *insert a maniac's laugh here*

- Sam

Edit, wow, i should really refresh page before i reply"

[undercoveryankee]

Any chance we'll see ground effect lift at some point?

http://upload.wikimedia.org/wikipedia/en/thumb/5/5f/Lun_Ekranoplan.jpg/220px-Lun_Ekranoplan.jpg

It could be really interesting as a landing mode for large spaceships, ie. have just enough lift to pull out of a suicide dive close to the water when the ground effect starts to matter, apply airbrakes and soft land as a boat, take off with lifting body and then return to space with >1 TWR.

Basically a lifting body spaceplane that only has enough lift within a few dozens of meters of the surface and then has to transition to acting more like a rocket really low.

Ferram was never able to find a model for ground effect that delivered acceptable performance and accuracy in classic FAR. The voxel model might open up some new lines of investigation once nuFAR is solid for normal flight.

[Vegemeister]

On wing strength, should the default not be whatever makes the mass the same as in stock? That seems as good a point as any.

The way wing mass is calculated now, that wouldn't work. The mass of a wing part, as far as I can tell, is proportional to the total area downstream of the root of that part. IIRC, Ferram chose the proportionality constant based on the specifications of a real airplane back when the system was first implemented. This has the effect that the inner parts of a wing are heavier than the outer parts, and the more layers of parts you have going out from the fuselage, the heavier the wing is. See examples.

Edited May 5, 2015 by Vegemeister

[tetryds]

Oh, by the way, you can make functional fairings out of struts now.

Struts and fuel pipes are properly voxelized.

[sam.johnson841]

Surly the gaps will allow air through? Or do the voxels ignore the gaps if they are small enough?

Also, I miss FAR from 0.90, is the dev build stable enough for use, i don't mind about the odd bug?

- Sam

[tetryds]

Surly the gaps will allow air through? Or do the voxels ignore the gaps if they are small enough?

Also, I miss FAR from 0.90, is the dev build stable enough for use, i don't mind about the odd bug?

- Sam

If the gaps are small enough it will mean that there is no gap.

The dev build is stable and everything, the only problem is that derivatives don't work and the graphs are not 100% accurate.

At least on the one I am using.

So, if you can eyeball everything, go ahead.

[cantab]

The way wing mass is calculated now, that wouldn't work. The mass of a wing part, as far as I can tell, is proportional to the total area downstream of the root of that part. IIRC, Ferram chose the proportionality constant based on the specifications of a real airplane back when the system was first implemented. This has the effect that the inner parts of a wing are heavier than the outer parts, and the more layers of parts you have going out from the fuselage, the heavier the wing is. See examples.

I wasn't aware of that. It may be "realistic", but to me that seems so counter to how KSP in general works that I don't feel FAR should be working that way.

[John FX]

Nice explanation wanderfound.

It explains this type of craft design.

Edited May 5, 2015 by John FX

[futrtrubl]

I wasn't aware of that. It may be "realistic", but to me that seems so counter to how KSP in general works that I don't feel FAR should be working that way.

You could say that about the FAR aerodynamic model itself though.

[Hodo]

Nice explanation wanderfound.

It explains this type of craft design.

http://www.cirrusimage.com/air/f-104_starfighter.jpg

http://test.fiddlersgreen.net/aircraft/Lockheed-F104/IMAGES/3View-Lockheed-F-104.jpg

Yeah the F-104 Starfighter design works surprisingly well in NuFAR if you want to see how an aircraft works at high mach speeds. But the 104 is basically a manned missile when it comes to aircraft, and you dont know how thin those wings are until you see them in real life.

[John FX]

For a contract I built a rocket drop pod, basically a LT-45, fuel tank some tail fins and a detachable pod with chute so i could visit the island runway.

Once it got to 300-400m/s it flew quite well. Had trouble getting slow enough to deploy the chutes and drop safely though.

[Surefoot]

Voxels are missing the bottom side of MK2 cargo bays:

[DundraL]

I wasn't aware of that. It may be "realistic", but to me that seems so counter to how KSP in general works that I don't feel FAR should be working that way.

I kinda feel the same way about this myself. I like the idea behind it but it really adds alot of hassle to the design process, and I REALLY dont like the way it got implemented. You can have have incredibly different wing mass depending on how you build the exact same wing. That and you often end up with wings denser than solid steel on some larger craft. This means wings as subassemblies are a big no no. I'm still hoping for a way to at least "set all wings to X strength" or a way to change the default strength.

Fun exercise: Make a 2X4 grid of wing parts on one side of an aircraft by daisy-chaining wing panels. Now make the same wing on the other side out of four 1X2 sections. Your CoM wont even be inside your fuselage.

Wish it based part weight on distance from the CoM of your craft rather than whats attached to that part.

[jrandom]

Fun exercise: Make a 2X4 grid of wing parts on one side of an aircraft by daisy-chaining wing panels. Now make the same wing on the other side out of four 1X2 sections. Your CoM wont even be inside your fuselage.

Wish it based part weight on distance from the CoM of your craft rather than whats attached to that part.

Whoa... that's... actually kind of a problem. As in, a genuine one.

[AndreyATGB]

Voxels are missing the bottom side of MK2 cargo bays:

Judging by the sudden decrease in area as well, I'd say they don't get recognized at all. Or maybe it takes into account the fact that it's hollow (shouldn't matter for area anyway right?).

[thorfinn]

So guys, how much of a trouble is the area ruling?

I like the idea in principle but I'm quite worried it will be a pain to respect area ruling in KSP with the limited choices we have, what's the experience up to now?

[Surefoot]

Judging by the sudden decrease in area as well, I'd say they don't get recognized at all. Or maybe it takes into account the fact that it's hollow (shouldn't matter for area anyway right?).

Upper part (mobile doors) is actually alright, and doors are properly voxelized wether they are open or closed. Only the lower half is missing O_o

So guys, how much of a trouble is the area ruling?

I like the idea in principle but I'm quite worried it will be a pain to respect area ruling in KSP with the limited choices we have, what's the experience up to now?

With only stock parts it will be a bit painful. With pwings and procedural parts: let the fun begin

[futrtrubl]

So guys, how much of a trouble is the area ruling?

I like the idea in principle but I'm quite worried it will be a pain to respect area ruling in KSP with the limited choices we have, what's the experience up to now?

Not an issue from everything I have seen here and experienced myself. Check back a few pages for examples of craft that follow the area rule.

Whoa... that's... actually kind of a problem. As in, a genuine one.

Not really. Prefectly realistic and intuitive. The wings inboard of other things absolutely have to be stronger (heavier) to be as structurally sound with more forces to deal with (it's own and anything attached to it) plus those forces further out are magnified by the lever arm that a wing is.

I kinda feel the same way about this myself. I like the idea behind it but it really adds alot of hassle to the design process, and I REALLY dont like the way it got implemented. You can have have incredibly different wing mass depending on how you build the exact same wing. That and you often end up with wings denser than solid steel on some larger craft. This means wings as subassemblies are a big no no. I'm still hoping for a way to at least "set all wings to X strength" or a way to change the default strength.

Fun exercise: Make a 2X4 grid of wing parts on one side of an aircraft by daisy-chaining wing panels. Now make the same wing on the other side out of four 1X2 sections. Your CoM wont even be inside your fuselage.

Wish it based part weight on distance from the CoM of your craft rather than whats attached to that part.

But they aren't the exact same wing. They have completely different properties and different wing loading. If you tried to make an asymmetrical wing like that in rel life you would absolutely expect one to be heavier than the other. That the density goes up too far is because you can't change the thickness of a wing.

If it was based on distance to CoM, heavier or lighter closer to CoM? If heavier then you still get the same thing with wings stacked out and craft with wings tucked in would be penalized despite being structurally more sound. If lighter..... that would make no sense.

Edited May 5, 2015 by futrtrubl

[blowfish]

So guys, how much of a trouble is the area ruling?

I like the idea in principle but I'm quite worried it will be a pain to respect area ruling in KSP with the limited choices we have, what's the experience up to now?

There is a smoothing setting which acts as a difficulty scale - the more smoothing that is applied to your craft, the less that strict area ruling matters.

[DundraL]

But they aren't the exact same wing. They have completely different properties and different wing loading. If you tried to make an asymmetrical wing like that in rel life you would absolutely expect one to be heavier than the other. That the density goes up too far is because you can't change the thickness of a wing.

If it was based on distance to CoM, heavier or lighter closer to CoM? If heavier then you still get the same thing with wings stacked out and craft with wings tucked in would be penalized despite being structurally more sound. If lighter..... that would make no sense.

It IS the same wing, but built differently.

Edited May 5, 2015 by DundraL

[futrtrubl]

http://i.imgur.com/LfWyTKB.png

It IS the same wing, but built differently.

Except that on one side almost all the forces have to be support by one or two panels rather than the 4 panels on the other side, so those 1 or 2 panels have to be stronger and so heavier.