Official FAR Craft Repository

[BT Industries]

On 6/28/2016 at 0:47 AM, Sparker said:

I've been experimenting with the amazing B9 procedural wings mod and made this little spaceplane having something in common with other lifting body designs

May I request a download for this wonderful looking craft?

[raxo2222]

Are splaceplanes, that use atmosphere (and fuel for conventional engines, as nuclear powered can run on pure atmosphere) flying at more than 5 mach possible?

I'm using RSS

[Van Disaster]

On 20/08/2016 at 6:26 PM, raxo2222 said:

Are splaceplanes, that use atmosphere (and fuel for conventional engines, as nuclear powered can run on pure atmosphere) flying at more than 5 mach possible?

I'm using RSS

Engines and heat - if you're low enough to run atmospheric engines then you'll probably burn up before you hit M5.0, if you can find any engines which will get you that fast. Aerodynamically there's nothing stopping you doing it.

[treasonousdog]

can someone help me figure out what is wrong with this plane? I have tried everything: 1 engine, 2, 3, engines on the top, on the bottom, near the tail, near the front, slanted wings, high wings, low wings, v tail, cruciform tail, and pretty much everything else. landing gear is aligned with the absolute grid.

yet i can't get a bit of lift. if i clear the runway, it goes into a very slow, inevitable descent no matter how hard i pull back on the stick.

http://imgur.com/c4DAMmE.jpg

Edited September 9, 2016 by treasonousdog

[Rodhern]

5 hours ago, treasonousdog said:

 ... it goes into a very slow, inevitable descent no matter how hard i pull back on the stick.

http://imgur.com/c4DAMmE.jpg

If you get the choice between a slow pitch down (when applying full stick) and a more rapid one (when the stick is at neutral or forward), then your aircraft is probably close to functioning. Btw. do you see the elevators move correctly to control inputs?

In that case you need more pitch authority somehow. Maybe you can shift the CoM further back, or extend the tail on the design Is it flaps you have on the trailing edges? If so, does the plane behave the same in all flap configurations?

[Van Disaster]

Well, kinda hard to really see what's going on without any of the FAR panels, but:

Taking a guess, the CoM is possibly where the yellow blob is, and the CoL possibly around the blue blob ( it moves with speed, so you can never really say "CoL here" ). In that case CoL is pushing up harder than the tail can push down.

Spoiler

 

Next guess, you haven't got the control surfaces set up right - how are the surfaces on the wings set up?

If CoM really is that far forwards ( probably a bit too far forward in that pic ) then it's considerably forwards of the rear gear, so that would partly explain why you can't pull off the runway.

What's Mw for default altitude/speed in the second FAR panel?

I found an early career aircraft to compare the layout, you can see where my rear gear is and that one has a heavy sci jr and the engine + fuel tank rather further aft of yours.

Spoiler

 

Edited September 9, 2016 by Van Disaster

[treasonousdog]

4 hours ago, Rodhern said:

If you get the choice between a slow pitch down (when applying full stick) and a more rapid one (when the stick is at neutral or forward), then your aircraft is probably close to functioning. Btw. do you see the elevators move correctly to control inputs?

In that case you need more pitch authority somehow. Maybe you can shift the CoM further back, or extend the tail on the design Is it flaps you have on the trailing edges? If so, does the plane behave the same in all flap configurations?

it is flaps on the trailing edges. the inner ones act as flaps while the outer are ailerons. i have tried taking off with flaps on and off. off i get the result listed above, on i get a violent jump around 100 m/s and the plane blows up.

47 minutes ago, Van Disaster said:

Well, kinda hard to really see what's going on without any of the FAR panels, but:

Taking a guess, the CoM is possibly where the yellow blob is, and the CoL possibly around the blue blob ( it moves with speed, so you can never really say "CoL here" ). In that case CoL is pushing up harder than the tail can push down.

  Reveal hidden contents

 

Next guess, you haven't got the control surfaces set up right - how are the surfaces on the wings set up?

If CoM really is that far forwards ( probably a bit too far forward in that pic ) then it's considerably forwards of the rear gear, so that would partly explain why you can't pull off the runway.

What's Mw for default altitude/speed in the second FAR panel?

I found an early career aircraft to compare the layout, you can see where my rear gear is and that one has a heavy sci jr and the engine + fuel tank rather further aft of yours.

  Reveal hidden contents

 

i'll get a FAR display for you later if you want one, but won't be able to until this afternoon as i'm at work until then.

Anyways, you are basically right about where the two centers are, except the COM is a bit further back. i tried to make sure the rear gear was very close to it. are you saying though that the COL needs to be very close to the COM? because currently that is not the case. I'm still fairly new to FAR mechanics, and i know having a COL far away from the COM in default is not a major issue.

thanks for the help

[kcs123]

Not necessary COL need to be close to COM, but if it is not , you need larger surface on elevators(tail) and larger deflection angle on them too than you need if your main wing COL is closer to COM. Check links in my signature to find out a bit more info about it.

[steve_v]

Okay, request: Anyone got a working seaplane / flying-boat (extra cookies for supersonic) design?
I have plenty of effective aircraft here, but nothing I build seems to survive a water landing intact. When a landing seems to be going well (as in actually skimming the surface), suddenly it's like hitting a brick wall, and then there's just a large debris field. Often with parts catapulted ~2km away.
I can't help thinking there's something funny about water drag, either that or flying-boats are just really hard?

Gah, this is impossible. 77m/s, 0.65m/s vertical, kaboom. Enormous, instant explosion. not a single joint remains, AFAICT. What's a safe landing speed on water anyway?

Edited September 9, 2016 by steve_v

[kcs123]

A bit obsolete, as it is made for KSP 1.0.5 and it is not supersonic.

 

Another one is made in KSP 1.1.2., require IR mod:

Full album on this link. (For some reason i tis no longer possible to post album on forum, while old post still shows them properly)

I used electrical engines from KAX mod for seaplanes for a reason. It is much easier to have stable landing slope and control touchdown speed due to high responsive throttle/thrust from electrical engines.

Jet engines variants are possible, but much harder to accomplish, you would probably want to use some pilot assitance mod, to accomplish steady landing slope.

A bit of advice, when you touch down water, don't try to brake imediately. It is best to have nose slightly pitched up, while having vertical velocity for about minus 1 - 2 m/s. Once your craft is steady on water, throttle down engines and engage spoilers/brakes. For final stop, electrical engines are useful too, as they can reverse thrust, so it can be used as brakes too.

Edited September 9, 2016 by kcs123
imgur album not showed properly

[steve_v]

1 hour ago, kcs123 said:

you would probably want to use some pilot assitance mod, to accomplish steady landing slope.

Yup, that's how I got a steady 0.68m/s vertical speed.

1 hour ago, kcs123 said:

A bit of advice, when you touch down water, don't try to brake imediately.

Really not even getting that far... kaboom on touchdown, or suddenly 'digs in' moments after. Either way, instant disintegration.

1 hour ago, kcs123 said:

It is best to have nose slightly pitched up

Target landing speed (nice and safe on the runway): ~7.5° AoA @ ~75m/s. Too fast?

The current goal is supersonic flying-boat.

I've got the supersonic, and the flying is working out just great...
The boat bit is driving me nuts. The best I have managed so far is destroying only all the tail sections. If I have to use all 50m/s impact tolerance parts for the floats it's going to get real ugly. Water 'aint that hard anyway.

Floats just fine, with just the bottom edge of the outer pontoons submerged. Centre hull section is 1.25m structural fuselage and type b tail booms (3 rows) clipped into the underside of the mk.2. Can't really see any other parts that give a remotely boat-like profile. Only 200 fuel on board to try to get the landing speed down, I'd kinda like more...

----
Okay, tried putting floats on old, slow, early-career prop-driven taildragger - about the simplest aircraft I have here. Same insta-stop on touching down, flips over and disintegrates.

It's really not this hard in stock. Hell, stock has a supersonic flying-boat. Lands fine in stock, disintegrates on touchdown in FAR. Same goes for the Gull.

Tested the aircraft in my screenie without FAR, guess what: It lands just fine, skimming across the surface as expected, takes off fine too. No insta-stop, no explosions.

 

----
So I tried to land the stock Osprey in FAR, as soon as I touch the water, this happens:


From ~70 m/s to ~5ms instantly, nose digs in and breaks off, craft catapaulted ~100m into the air. This is like trying to land on a sticky trampoline.

Edited September 9, 2016 by steve_v
Spelling

[kcs123]

Have to agree, water is a bit odd, compared to stock. I was having issues with accelerating buoyancy probes when tiped over in the past. Ferram fixed that later on. You don't have a feeling that water is watrer at all. Ferram explained it that is almost impossible to improve it further without breaking other stuffs. Have to wait for KSP 1.2 to see if things can be improved with new unity game engine.

70-80 m/s is a bit too fast. try to aim for craft designs capable to land at ~60 m/s with ~5 AoA angle and -1m/s vertical speed.
To accomplish that, you need lightweight plane with wide wing span. Not exactly suitable combo for supersonic flight. That is point where variable geometry wings help a lot. Although you need to overcome other kind of issues with IR parts.

EDIT:

Forgot to say, try with B9 parts for floating parts. Those are slightly heavier than stock but have better crash tolerance too.

EDIT2:

And you probably want to have some space between water skis and wings/engines. Try to minimize parts that are below water.

Edited September 9, 2016 by kcs123

[FourGreenFields]

5 hours ago, treasonousdog said:

it is flaps on the trailing edges. the inner ones act as flaps while the outer are ailerons. i have tried taking off with flaps on and off. off i get the result listed above, on i get a violent jump around 100 m/s and the plane blows up.

i'll get a FAR display for you later if you want one, but won't be able to until this afternoon as i'm at work until then.

Anyways, you are basically right about where the two centers are, except the COM is a bit further back. i tried to make sure the rear gear was very close to it. are you saying though that the COL needs to be very close to the COM? because currently that is not the case. I'm still fairly new to FAR mechanics, and i know having a COL far away from the COM in default is not a major issue.

thanks for the help

If the CoL is far behind the CoM that usually means high pitch stability. Not nessecarily bad, but means you need a powerfull elevator to pull high AoAs.

Put simply, you'll want CoL and CoM close to each other for agile planes (stuntplanes, fighters) and possibly planes with high wingloading (as they may need high AoAs to fly slow). CoL further behind if the plane is meant to be easy to fly (trainers and stuff). But even "futher behind" shouldn't be overdone, or you risk not being able to pull the AoA to sustain level flight - which is probably what is happening to your plane.

You can, ofcourse, build agile planes with CoL far behind CoM - a very big/powerfull elevator can overcome stability, thrust vectoring can help (especially at low speed), and some planes may have lower stability at certain speeds (one kind of layout I used had significantly lower pitch stability at exactly 0.9M for example). But it's a bit like building supersonic planes without area ruling them - possible (as the Bell X-1 proved), but there are easier ways.

 

 

A better indicator for how pitch-stable a plane is are the "pretty graphs" in the FAR interface. There's a yellow (iIrc) line, and if it's going down as AoA increases, the plane is pitch-stable. Good way to see if the plane is, i.e. getting more or less stable as AoA increases. Also usefull to see if the plane will keep the AoA required for level flight without trimming (if you want that, I'd recommend adding an Angle of Incidence (AoI)), and to get the critical AoA.

You can also calculate the graphs with pitch input (only elevator, not RCS/thrust vectoring iIrc) to see the maximum AoA you can pull. I'd recommend you to do that, and compare that to the AoA required for level flight (as can be claculated using the "scary numbers" section).

The "scary numbers" can also help determine stability in general, but not all of them (not even all of the coloured ones) are vital, and I found it hard to figure out how stable the plane is - only if it is stable at all, or not.

[Van Disaster]

Yes, the yellow graph & Mw derivative will tell you how much nose-down the plane is generating - the CoL ball isn't really a good indicator because it's dependent on a lot of things, and Ferram has said several times he'd quite like to remove it. I use it to help gauge what my flaps are going to do, mostly. If the flaps are behind takeoff CoL you're going to get pitch-down from them, which isn't generally that useful. Once you get airborne the best indicator of balance is your pitch indicator, if it's neutral while you're cruising you've got the most efficient balance.

--

Flying boats?

Amphibian technically. Possibly supersonic in a steep dive

FAR water seems to be less dense than stock given the lower ( water ) drag, but I don't think it replaces stock bouyancy settings? so things sink more. That means on landing stuff has a habit of sinking it's nose which will suddenly get all the water drag, and over you go.

[Remembers]
Here's something fairly early from the last career run, took forever to stop it flipping on landing and even now it needs a really careful flat touchdown. I just kept extending the nose until the centre of bouyancy was far enough in front.

Edited September 9, 2016 by Van Disaster

[Van Disaster]

Experimental supersonic flying boat, uses a few SXT parts but was just to see if I could do it.

Supercruise:


Wet thrust ( I have no idea when it'd have stopped accelerating, was getting a bit fluttery at that alt )

Slow speed before landing:

Landing was no problem, bobbed a bit but the water profile is pretty gentle:

Takeoff needed a bit to get unstuck - a variable incidence wing would work really well, might give that a shot at some point. Securing it is not going to be fun though.



And a somewhat more problematic ( read overweight ) SXT pax version:

Spoiler

 

Edited September 10, 2016 by Van Disaster

[steve_v]

Well... I think I'm seeing everything being longer than mine maybe what I'm building is just too short and the nose is pitching into the water.
But career game, no Mk.3 parts yet. Project on hold I guess.

[Van Disaster]

I did discover if I took all the fuel out of the tail section it'd break off on landing, so perhaps you can make sure your tail parts are tanks. I use KJR always, too.
 

Spoiler

 

I grafted all the aero parts onto a Mk2 fuselage, seems to work just fine ( well, takeoff is a bit fast ) if you don't overfuel it.

Edited September 11, 2016 by Van Disaster

[Van Disaster]

And just for completeness, a SSTO amphibian proof of concept. Not sure it has bouyancy for much payload like that.

 

Spoiler

 

 

The thrust axis is way off CoM so you're not going to be burning much in space ( or at least not very hard ), but hey, it works.

 

[Deizelpunk]

Can anyone help me with making a flying wing? I've made a few small ones but im having trouble making larger designs that work.

[FourGreenFields]

6 hours ago, Deizelpunk said:

Can anyone help me with making a flying wing? I've made a few small ones but im having trouble making larger designs that work.

Aerodynamically stable (basicly translating to di-/anhedral wingtips or stuff) or artificial stability? Messed with both, mostly for the 5th Generation Fighter Challenge.

Size? Payload? Speed? SSTO? Any requirements for takeoff and landing (other than being able to do that at KSC)? Existing design that you want improved?

[Van Disaster]

7 hours ago, Deizelpunk said:

Can anyone help me with making a flying wing? I've made a few small ones but im having trouble making larger designs that work.

We maybe could, if you told us what the trouble was. How big is larger?

[Deizelpunk]

2 hours ago, Van Disaster said:

We maybe could, if you told us what the trouble was. How big is larger?

The small drones ive been making are based on the mk0 fuselage system, i want to make one scaled up using mk2 fuselage system. Kinda like the X45.

 

3 hours ago, FourGreenFields said:

Aerodynamically stable (basicly translating to di-/anhedral wingtips or stuff) or artificial stability? Messed with both, mostly for the 5th Generation Fighter Challenge.

Size? Payload? Speed? SSTO? Any requirements for takeoff and landing (other than being able to do that at KSC)? Existing design that you want improved?

Its gotta have one small cargo bay (for munitions) and it cant have a vertical stabilizer in the middle. Im going for something like the X45, and i want it to fly and land nice and easily.

[Deizelpunk]

4 hours ago, Van Disaster said:

We maybe could, if you told us what the trouble was. How big is larger?

 

5 hours ago, FourGreenFields said:

Aerodynamically stable (basicly translating to di-/anhedral wingtips or stuff) or artificial stability? Messed with both, mostly for the 5th Generation Fighter Challenge.

Size? Payload? Speed? SSTO? Any requirements for takeoff and landing (other than being able to do that at KSC)? Existing design that you want improved?

I want a X47 looking design, fuselage blended into the wing. my small drones have the fuselage pretty separate.

[FourGreenFields]

1 hour ago, Deizelpunk said:

The small drones ive been making are based on the mk0 fuselage system, i want to make one scaled up using mk2 fuselage system. Kinda like the X45.

 

Its gotta have one small cargo bay (for munitions) and it cant have a vertical stabilizer in the middle. Im going for something like the X45, and i want it to fly and land nice and easily.

 

2 minutes ago, Deizelpunk said:

 

I want a X47 looking design, fuselage blended into the wing. my small drones have the fuselage pretty separate.

Ok, Mk2 fuselage, blended wing-body. High speed, and some payload (judging by X-45 and X-47 a bomber/attacker, so doesn't need to be that manoeuvreable). Pilot-friendly handling. Going to try that later today. o7

[Deizelpunk]

 

17 minutes ago, FourGreenFields said:

 

Ok, Mk2 fuselage, blended wing-body. High speed, and some payload (judging by X-45 and X-47 a bomber/attacker, so doesn't need to be that manoeuvreable). Pilot-friendly handling. Going to try that later today. o7

thanks!

Edited September 12, 2016 by Deizelpunk
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