Official FAR Craft Repository

[tetryds]

There is no such balancing on FAR, in engineering you almost never have "plain better" for everything.
Unlocking parts later on the tech tree simply gives you more flexibility, allowing you to shape the wings better and other things like that.
For example a certain all-moving wing part can have lower transonic drag when placed on a certain location at the aircraft if compared to the others.

[qromodynmc]

It was really boring recently, I decided to install FAR. I always love making planes and trying to find their limits.

So i was wondering if i could make supersonic plane with those small jumo engines, i tried using one engine first, it couldnt pass over 330ms. Then i tried tri-jet configuration and succesfully passed beyond 470ms at sea level.

Some funky things going on with those yellow blue lines at the end, I really dont understand what they mean exactly but i can make some guesses, i think pressure is really high at the end parts.

Edited February 17, 2016 by qromodynmc

[Hodo]

21 hours ago, qromodynmc said:

It was really boring recently, I decided to install FAR. I always love making planes and trying to find their limits.

So i was wondering if i could make supersonic plane with those small jumo engines, i tried using one engine first, it couldnt pass over 330ms. Then i tried tri-jet configuration and succesfully passed beyond 470ms at sea level.

Some funky things going on with those yellow blue lines at the end, I really dont understand what they mean exactly but i can make some guesses, i think pressure is really high at the end parts.

I think if you were to just create a true delta wing design out of it, you would get rid of some of the shock at the rear of the aircraft and it would possibly go faster.  I would also add more control surfaces to it. 

[Hodo]

So while I am here... my latest cargo SSTO the SP-517.  72 tons into an orbit of 100km x 100km and a docking with my space station to refuel the station.

 

Edited February 18, 2016 by Hodo

[qromodynmc]

On 18.02.2016 at 9:50 PM, Hodo said:

I think if you were to just create a true delta wing design out of it, you would get rid of some of the shock at the rear of the aircraft and it would possibly go faster.  I would also add more control surfaces to it. 

Yeah! I really dont know why i didnt used delta wing on this, I must try it in first chance.

edit- with delta wing and some little changes now it does 503 ms at sea level.

Edited February 19, 2016 by qromodynmc
update

[Hodo]

2 hours ago, qromodynmc said:

Yeah! I really dont know why i didnt used delta wing on this, I must try it in first chance.

edit- with delta wing and some little changes now it does 503 ms at sea level.

There are many types of Delta wing designs.. I am partial to a cranked arrow delta but that is me.

Those are examples of my cranked arrow delta design.

[kcs123]

With crancked arrow delta a like designs it is easier to smooth out wave drag area, for that reason it is not uncommon choice. However, it might be more difficult to achieve roll/sideslip stability with such designs, probably it is a reason why there is not so many designs like this.

Btw, it seems that you have slightly extra oxidizer in tanks that was left unused in flight. With those removed you might squeeze out slightly more dV.
Usually on first test flight I create screenshot with resource panel opened when it is time to switch engine mode. That way you can calculate how much of oxidizer you can remove from craft.
Slightly more than that is also good, so you can always have some liquid fuel for last maneuver on runway aproach if you didn't make reentry perfectly to just glide to runway.

[Hodo]

35 minutes ago, kcs123 said:

With crancked arrow delta a like designs it is easier to smooth out wave drag area, for that reason it is not uncommon choice. However, it might be more difficult to achieve roll/sideslip stability with such designs, probably it is a reason why there is not so many designs like this.

Btw, it seems that you have slightly extra oxidizer in tanks that was left unused in flight. With those removed you might squeeze out slightly more dV.
Usually on first test flight I create screenshot with resource panel opened when it is time to switch engine mode. That way you can calculate how much of oxidizer you can remove from craft.
Slightly more than that is also good, so you can always have some liquid fuel for last maneuver on runway aproach if you didn't make reentry perfectly to just glide to runway.

 

Oh on the last two pictures?  That last one I have since modified the design that is an old picture.  I am not even sure I still use that craft anymore, I like it but I dont use it. It was an early SSTO Fighter/Attack craft, with an internal weapons bay.   But had a limited payload in the bay, I think a max of 6 500lb bombs, or 3 CBUs.  Which isnt a great deal, so I have since retired the design and moved on to others.  I am still working on refining them but they are a secondary project at this time.  I have to get my deep space exploration back underway.  I have an Ion powered long range exploration vessel in orbit now that is waiting for a window to head out to Dres as a shake down run.  

As for the roll and sideslip problems on the cranked arrow wings, those are easily overcome by doing the V tail designs or going with a twin tail setup.  

The next two are my XF-149A design, which was a STOVL/VTOL fighter with a super cruise ability

The tail went through a few redesigns over the time of its development...

This was the final configuration for the fighter. 

Edited February 20, 2016 by Hodo

[Guest]

 

Tweaked it a bit, I didnt know that the close coupled canard actually arent elevator but big lerx..

Download on kerbalX, need a couple of mods .

[Hodo]

All I did was deploy my newer.... mostly, PV-7 VTOL rescue and science aircraft.

[Guest]

A few more tweaks later....

craft : https://kerbalx.com/crafts/6835

 

Edited February 21, 2016 by RevanCorana

[Rodhern]

As you can probably tell I am still new to FAR.

I have this simple craft. It is a command pod, three girder boxes and four wing parts.

From looking at the picture I would guess that a positive pitch up rotation will induce a upward acceleration (negative Z-direction acceleration) as the wing surfaces are forced downwards.

On the FAR stability derivatives tab however the Zq derivative is positive. Can someone explain that to me?

[ferram4]

Simple; you're absolutely correct about how you expect things to behave.  What you're not correct about is the orientation of the axes; Z+ is measured downwards.  That's so that a positive angle of attack is measured as pitch up for the plane.  Everything else comes from that.

[Rodhern]

14 hours ago, ferram4 said:

Simple; you're absolutely correct about how you expect things to behave.  What you're not correct about is the orientation of the axes; Z+ is measured downwards.  That's so that a positive angle of attack is measured as pitch up for the plane.  Everything else comes from that.

Sure, I just need a bit more help then. Aren't you expecting an upward acceleration of the craft as well (i.e. negative Z)?

Edited February 22, 2016 by Rodhern
clarification

[Rodhern]

Bonus question: I have a simple craft that appears to show about half the Cl and L/D in the static analysis graph as compared to the FAR info window in flight. It is hard to tell because I am just flying about and it is not a real precise measurement as such. Anyway, have any of you noticed anything similar?

Edit: I restarted the game and now the static graph seems correct. Don't know what I did wrong the last time.

Edited February 22, 2016 by Rodhern
seems to work correctly again now

[Guest]

CTRL+Y tends to induce such errors in the graphs

 

Edited February 22, 2016 by RevanCorana

[Rodhern]

6 hours ago, RevanCorana said:

CTRL+Y tends to induce such errors in the graphs

Aha, I see now that you are right, and that CTRL-Z is almost as bad. Now that I know I can get a particular craft to consistently mess up the graphs. Two rotations followed by two CTRL-Z messes it up, a move and yet another CTRL-Z restores the graph.

Thanks a lot. I am slowly learning the quirks of FAR.

[Rodhern]

Sign of Zq and Xq explained.

I don't know why, but I need more help to understand the sign of Zq and Xq. To me they appear to be 'the wrong way around' in the current version.

So first thing first. Let me 'explain' how I see Xq (for a simple craft) and you can tell me where my chain brakes.

• The initial situation is a stable forward flying craft at a positive AoA (fixed positive pitch).
• The pitch moment is initially zero (i.e. pitch kept constant).
• At the initial situation the craft experiences some rearward force (negative X acceleration, X0) from drag.
• To calculate the derivative we must determine the X acceleration in a situation similar to the initial situation, but this time assuming the craft is subject to a small pitch up rotation motion (a persistent positive pitch rate, q1).
• The new X direction acceleration, X1, is probably still negative, but we are only interested in the relative change anyway. That is, we want to know Xq = (X1 - X0) / (q1 - 0).
• We might for technical reasons consider using an initial situation with a negative q0 instead of a straight zero, but that should not interfere with any of the arguments (i.e. Xq = (X1 - X0) / (q1 - q0)).
• If the pitch up rotation movement is propelling the craft forward (i.e. if the isolated effect of the rotation is fighting the drag) then Xq should show a positive number.
• By reasons of symmetry I get the below table.

dir. of rotation vs effect	propelled forward	increased drag
pitch up rotation	positive Xq (+)	negative Xq (-)
pitch down rotation	negative Xq (-)	positive Xq (+)

First question then is: Do the bullet points make sense, or maybe some of them are plain wrong?

Second question (in case the bullet points are valid): Does your FAR stability derivatives correspond to the above table? I don't feel mine does.

B.t.w. I was wondering if there is a more comprehensive explanation of the FAR formulas than the few Wiki pages. I don't think I will be able to understand the source code. How did you, the more experienced players, learn the FAR 'rules'?

And just one more question. Do you have a good trick to make sure the figures in the SPH (graphs and derivatives) are updated? (simply pressing the button is not always enough).

[Wjolcz]

I have a question about control surfaces stalling. I have this flying wing that flies really well except for when pitching up:

I remember having a flying wing that would work and be super manouverable, but I don't remember how I dealt with the problem. I mean the wobble when fully pitching up or down. Perhaps the surfaces that are used for pitching are too close to CoM? Should I add more sweep? Make them smaller? Any useful tips and help much appreciated.

Edited February 26, 2016 by Veeltch

[FourGreenFields]

11 hours ago, Veeltch said:

I have a question about control surfaces stalling. I have this flying wing that flies really well except for when pitching up:

*picture*

I remember having a flying wing that would work and be super manouverable, but I don't remember how I dealt with the problem. I mean the wobble when fully pitching up or down. Perhaps the surfaces that are used for pitching are too close to CoM? Should I add more sweep? Make them smaller? Any useful tips and help much appreciated.

Sounds like a very sudden stall to me. Would expect the FAR graphs to have a very steep drop of lift and a very steep increase in pitch-down force.

You could simply avoid stalling, reducing max deflection for your control surfaces and stuff like that.

Or you could kill any kind of lift/drag ratio by using vortex lift or whatsitcalled. Increases max AoA, and makes stalls less severe, but increases drag at high AoA a hell of a lot. If you want that, extend the leading edge near the root, use delta wings, and/or use low aspect ratio.

[Kitspace]

Hello!

I am trying to learn to design more maneuverable high speed planes to use as interceptor fighters and I have a problem that I need a piece of advice with.

I have tried several different designs but they all seem to suffer from the same issue to a certain extent.

If I decrease their static stability or increase the controls deflection limit the maximum angle of attack they can reach increases but the maximum rate of turn does not. The plane just moves further away from the prograde marker before settling into the same long slow lazy turn as if it was another bulky and overloaded cargo transporter that I would usually design.

Increasing the static stability does not do any good here as well as it just makes the plane even more sluggish.

Presumably as a consequence of high control authority and slow reaction of the velocity vector these planes like to wobble a lot. Especially at high angles of attack where the plane usually jerks back and forth like crazy for some time before settling down both when increasing and decreasing control input.

The thing is the static stability graph shows no signs of stalling at all and the right click menus only show less than one percent of stalling for short amounts of time given that the speed remains reasonable after all this wobbling.

So I do not know where to look to fix that. At the moment the planes are quite controlable they just oscillate around the direction they should be facing pretty much all the time instead of just smoothly pointing in that direction. Increasing speed reduces the amplitude of oscillation but also reduces the angle of attack it starts at ultimately causing the plane to wobble a little bit even when trimmed and left alone in level flight.

What do I need to do in general to increase the rate of turn that the plane is capable of and to make it follow the input smoothly without all the shaking and wobbling?

Any help would be greatly appreciated!

[Guest]

32 minutes ago, Kitspace said:

Hello!

I am trying to learn to design more maneuverable high speed planes to use as interceptor fighters and I have a problem that I need a piece of advice with.

I have tried several different designs but they all seem to suffer from the same issue to a certain extent.

If I decrease their static stability or increase the controls deflection limit the maximum angle of attack they can reach increases but the maximum rate of turn does not. The plane just moves further away from the prograde marker before settling into the same long slow lazy turn as if it was another bulky and overloaded cargo transporter that I would usually design.

Increasing the static stability does not do any good here as well as it just makes the plane even more sluggish.

Presumably as a consequence of high control authority and slow reaction of the velocity vector these planes like to wobble a lot. Especially at high angles of attack where the plane usually jerks back and forth like crazy for some time before settling down both when increasing and decreasing control input.

The thing is the static stability graph shows no signs of stalling at all and the right click menus only show less than one percent of stalling for short amounts of time given that the speed remains reasonable after all this wobbling.

So I do not know where to look to fix that. At the moment the planes are quite controlable they just oscillate around the direction they should be facing pretty much all the time instead of just smoothly pointing in that direction. Increasing speed reduces the amplitude of oscillation but also reduces the angle of attack it starts at ultimately causing the plane to wobble a little bit even when trimmed and left alone in level flight.

What do I need to do in general to increase the rate of turn that the plane is capable of and to make it follow the input smoothly without all the shaking and wobbling?

Any help would be greatly appreciated!

Increasing angle of attack  increases lift, until you reach stall then it decreases..

Have you tried putting control surfaces on the forward part of your wings and set them to follow AoA% ?

Also move the center of mass as far back as possible while still being controlable to minimize the deflection of elevator.

As for wobble, adding strategically placed struts should do the trick most of the time

Edited February 28, 2016 by RevanCorana

[MightyDarkStar]

Type 400 'Velociraptor' High-Altitude Reconnaissance Aircraft

This thing can get up to 18.6k before the engine really begins to lose thrust. The low speed characteristics are something I'm really thankful to FAR for.

[Kitspace]

I tried moving the center of mass and center of pressure back and forth and seeing what happens and I said that. I found that moving both of them closer together increases the oscillation a lot while it does not make the plane turn faster. That is what confuses me here.

By wobble I mean that the whole plane oscillates up and down not that the joints are soft. Nothing to do with struts at all.

[FourGreenFields]

2 hours ago, Kitspace said:

Hello!

I am trying to learn to design more maneuverable high speed planes to use as interceptor fighters and I have a problem that I need a piece of advice with.

I have tried several different designs but they all seem to suffer from the same issue to a certain extent.

If I decrease their static stability or increase the controls deflection limit the maximum angle of attack they can reach increases but the maximum rate of turn does not. The plane just moves further away from the prograde marker before settling into the same long slow lazy turn as if it was another bulky and overloaded cargo transporter that I would usually design.

Increasing the static stability does not do any good here as well as it just makes the plane even more sluggish.

Presumably as a consequence of high control authority and slow reaction of the velocity vector these planes like to wobble a lot. Especially at high angles of attack where the plane usually jerks back and forth like crazy for some time before settling down both when increasing and decreasing control input.

The thing is the static stability graph shows no signs of stalling at all and the right click menus only show less than one percent of stalling for short amounts of time given that the speed remains reasonable after all this wobbling.

So I do not know where to look to fix that. At the moment the planes are quite controlable they just oscillate around the direction they should be facing pretty much all the time instead of just smoothly pointing in that direction. Increasing speed reduces the amplitude of oscillation but also reduces the angle of attack it starts at ultimately causing the plane to wobble a little bit even when trimmed and left alone in level flight.

What do I need to do in general to increase the rate of turn that the plane is capable of and to make it follow the input smoothly without all the shaking and wobbling?

Any help would be greatly appreciated!

There's 3 things that could be happening here I suppose:

• More than about 30° AoA, meaning low gain in lift when further increasing AoA
• High drag, leading to low speed, leading to less lift
• Very high wing loading, meaning your wings don't generate alot of lift compared to the weight of your craft

Tbh, they're all somewhat related. To reach high AoAs without stalling you need vortex lift afaIk (maybe slats would work though), which means alot of drag at high AoAs. And if you're not turning tight at 30° AoA and high-ish speed, your wingloading definitly is high.

Try increasing power to weight if your plane slows down too much, or decrease induced drag. Either way, increasing wing size almost always helps with turning.

 

About the wobble: Do you have FAR pitch assist enabled? If set up wrong it can lead to problems, if set up right it might be able to prevent that.

 

EDIT: On a related note: 5th Generation Fighter Challenge.

Edited February 28, 2016 by FourGreenFields