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

[samroberts]

Is there a way to enable this to run on x64 for windows? I will sign a waiver if needed saying that I know it will probably cause crashes and such.

[tempsgk]

Does bi plane wings work? On heavy aircraft in stock I often put biplane wings so the wingspan doesn't have to be a kilometre long to take off and I can take off at low speeds.

[BudgetHedgehog]

Is there a way to enable this to run on x64 for windows? I will sign a waiver if needed saying that I know it will probably cause crashes and such.

Recompile it yourself without the x64 check or use Linux.

Does bi plane wings work? On heavy aircraft in stock I often put biplane wings so the wingspan doesn't have to be a kilometre long to take off and I can take off at low speeds.

Yes, biplanes work. But not well, just like in real life. You end up with the wing interaction creating too much drag for the additional lift. Biplanes were only invented because they're structurally stronger. You don't really need as much 'wing' as you do in stock as you can get a fair amount from the lifting body effect.

[tempsgk]

So FAR takes into account that? As far as I know the more wing parts=the more lift. That's in stock though.

Also how high does a wing have to be to not have wing interaction.

[BudgetHedgehog]

So FAR takes into account that? As far as I know the more wing parts=the more lift. That's in stock though.

Also how high does a wing have to be to not have wing interaction.

Ah, now that, I don't know. All I know is that it's a thing. And yeah, for fun sometimes, I take my FAR planes into the stock soup and see how they act - one of my favourite SSTOs could barely maintain level flight. Another nice SSTO I like to make involves 2 Mk2 adapters, one intake, one RAPIER and some fins at the back for control. The Mk2 shapes are perfect for getting some advantage of the lifting body effect as that drone can easily make LKO but I assume it wouldn't even fly at all in stock. Also, Manley made a video today about Shuttle aerodynamics that touches on this subject a little - with FAR/NEAR, the whole underside of one acts as a nice flat surface for air to push against and keep you up but in stock, you need to add in just more wing segments.

[tempsgk]

That's true, in stock you generally need to add more wing segments. The problem is in FAR, in FAR I do think you still need to add more wing segments. but the line is very blurry so I need some accurate answers to clear it. Also I hear FAR dosen't think into account wing swept, a swept wing is pretty much the same as a straight wing in terms of mach effects.

Edited January 25, 2015 by tempsgk

[blowfish]

FAR takes wing interactions into account, which means that biplanes don't work particularly well at subsonic speeds, and very badly at supersonic speeds.

[tempsgk]

Is there a way to see this? Besides taking the craft out and testing though.

[Crzyrndm]

Is there a way to see this? Besides taking the craft out and testing though.

In the graphs, your L/D values should be noticably lower than a single wing of similar overall size (decreased lift and increased drag), and you might be able to see it in flight with the aero viz options.

[BudgetHedgehog]

Also I hear FAR dosen't think into account wing swept, a swept wing is pretty much the same as a straight wing in terms of mach effects.

Very much wrong. A quick look at the FAR graphs for straight wings and swept wings will show you that for supersonic speeds, swept wings are a lot better.

[Drew Kerman]

Does bi plane wings work? On heavy aircraft in stock I often put biplane wings so the wingspan doesn't have to be a kilometre long to take off and I can take off at low speeds.

do some searching here in the thread. Ferram weighed in on the topic of biplanes in good detail a few pages back

[kcs123]

@tempsgk, check links in my signature, you will find good and bad examples in STTO contest thread.

Rakaydos have also asked here about his bi-wing planes, ferram answared as I recall that two wing is only 30% better then one wing and that is only at subsonic speeds.

On supersonic speed it is pretty much dead weight. It will be easier to search this forum for his post to find better answer.

That contest was for KSP 0.25, but most of things still is valid. Main difference is new skin drag feature. Because of this you need to go for much higher altitude to be able to reach certain speeds. For jets it means that you need more air intake, more air intake also means more drag. So you will have to find sweat spot to make good plane.

In my previous designs for 0.25 I was able to reach needed speed near 20-22 km and then switch engine mode or switch to rocket. Now I need to reach 27 km to be able to go above 5 mach. That means that you need stable plane that can reach 27 km on low speed and low AoA.

Still, I was able to make again plane that lifts 30t payload. Whole plane is near 108t. It is based on my SpacePlane Mk2 V8, just with two more air intakes and new B9 procedural wings.

[tetryds]

@tempsgk: swept wings have so many pros to them that it does not make any sense to not use them.

Assuming that the person who told you that is sane, s/he could have mentioned NEAR, then there is no such thing as mach effects there, not that it does not model the wings properly.

@ksc123: true, it was a bit weird that any plane I built could always reach mach5 at 18km, and I like to build low altitude fighters.

Now there is a new niche to be explored.

Edited January 25, 2015 by tetryds

[Van Disaster]

492t on the runway/185t test payload approx, went up without too much drama and fuel to spare ( pitch authority is a continual problem... ). I note previous versions of this in 0.25 lifted more like 280t and I'm not really sure this one would despite having more wing area, so perhaps 300t total with two engines is now only really sensible with extremely careful design. I don't think I want to have to circumnavigate twice before even getting to rocket mode every single launch.

[Wanderfound]

So FAR takes into account that? As far as I know the more wing parts=the more lift. That's in stock though.

Also how high does a wing have to be to not have wing interaction.

Basic rule: unless you're building a WWI replica designed for extremely low-speed low-altitude aerobatics, forget about biplanes. For spaceplanes, a monoplane will always be better. And even heavy lifters may bot need as much wing as you think:

Notice the easy takeoff? You could probably halve the wings on that and still get it to work.

[LameLefty]

Notice the easy takeoff?

"Easy"? It looks like you're doing 197 m/s. That's 383 knots - no aircraft tire in existence can handle that kind of speed. Even if the image is blurred and it's only 107 m/s, that's still WELL above any kind of sane V1 speed for a real-world aircraft.

[Rebelgamer]

It's 197, the mach indicator is saying .4, which would be about right for sea level. Though the speed at rotation was probably more like 180 or so.

[tetryds]

About stacking wing parts, no they don't generate more lift on FAR, nor on NEAR (it got fixed on NEAR not long ago).

@Van Disaster: nice design.

You should try using leading edges to increase pitch authority, it's not like they break laws of physics or anything, they are just faster and stronger than real life.

Make sure you place them in front of your COM too.

(Well, I lied, but you can still use them normally)

Mach 0.4 on takeoff is fine if your plane is made of lead

[Wanderfound]

"Easy"? It looks like you're doing 197 m/s. That's 383 knots - no aircraft tire in existence can handle that kind of speed. Even if the image is blurred and it's only 107 m/s, that's still WELL above any kind of sane V1 speed for a real-world aircraft.

137m/s, not 197; about 265 knots. Concorde lifted at about 220kn, but Concorde didn't have oxidiser tanks or a Mainsail strapped on the back.

Kerbal aircraft tend to be substantially heavier than real-world equivalents, generally requiring higher take off speeds. Around Mach 0.35 is when I tend to lift the nose for most things, large or small. But if you can hit that speed halfway down the runway, it ain't a problem.

Regardless, the point stands: that plane is lifting off, without a stall, with minimal control inputs, halfway down the runway. Chop the wings in half and it'll still lift off, just with a bit more effort.

[smjjames]

Basic rule: unless you're building a WWI replica designed for extremely low-speed low-altitude aerobatics, forget about biplanes. For spaceplanes, a monoplane will always be better. And even heavy lifters may bot need as much wing as you think:

http://i1378.photobucket.com/albums/ah120/craigmotbey/Kerbal/Beta/Kerbodyne%20Showroom/Titan%208/screenshot372_zpsd7dfd71e.jpg

Notice the easy takeoff? You could probably halve the wings on that and still get it to work.

What are those wierd bits around the engine there?

[Van Disaster]

What are those wierd bits around the engine there?

Overlapping stock jets, it looks like.

[kcs123]

I'm not big fan of engine spamm. I rather want to make plane that can reach orbit at lower TWR than "1".

First prototype that reached orbit. It still needs tweaking, have to try deentry behaviour, better alignment of engine thrust with COM, but it reached orbit with excesive payload.

[bdito]

"Easy"? It looks like you're doing 197 m/s. That's 383 knots - no aircraft tire in existence can handle that kind of speed. Even if the image is blurred and it's only 107 m/s, that's still WELL above any kind of sane V1 speed for a real-world aircraft.

Who said anything about the real world? It's a pretty easy takeoff for KSP.

[Kitspace]

Easy?

I thought one of the things this mod does is making lift a function of the squared airspeed like it is.

Is not that supposed to give us the realistic V speeds?

[DaMichel]

Hey guys.

Still not convinced that intake drag is okay. Maybe it is just me. I'm using the latest FAR dev version and AJE 2.0.2. Could be that my config is messed up or it is a bad interaction between FAR and AJE or something like that. See for yourself

Javascript is disabled. View full album

Note the difference in drag force between cone inlets, circular intake and radial rectangular inlet. Am i alone with this?

Oh and it looks like i found a little glitch in the last pic with the force on the fuselage, but this is not my main issue here.

Cheers,

DM

P.S. @Wanderfound: Nice plane. Made something similar not too long ago

Edited January 26, 2015 by DaMichel