The 5th Generation Fighter challenge [FAR]

[Darth Lazarus]

@ Halsfury

very very helpfull. amazing how little changes affect the overall plane. espacily the wingsection and its strength. i havn't known, that the small wingsections are so weak compared to others. sad somehow, because they fit great for the original F-18 wingshape

now a download would be nice so that i can test it myself and use all your improvments for further development it still needs missles

Edited July 11, 2015 by Darth Lazarus

[Halsfury]

@ Halsfury

very very helpfull. amazing how little changes affect the overall plane. espacily the wingsection and its strength. i havn't known, that the small wingsections are so weak compared to others. sad somehow, because they fit great for the original F-18 wingshape

now a download would be nice so that i can test it myself and use all your improvments for further development it still needs missles

Here you go

http://www./download/r26blird449f97f/FAR_FA-18_Super_Hornet.craft

[Darth Lazarus]

Here you go

http://www./download/r26blird449f97f/FAR_FA-18_Super_Hornet.craft

thank you alot my friend

[Halsfury]

thank you alot my friend

You're welcome, send back notes on how it flies, maybe there's more room for improvement

- - - Updated - - -

Also thanks to everyone for participating in this challenge, I didn't know that so many people played in FAR, or would be interested

[Darth Lazarus]

the Halsfury Aerospace and Laz Corp. F/A-18 Super Hornet .... soudns good to me.

have her right now in my SPH and some adjustments on the wings droped the wave drag down to 0.80.

i will test how all characteristics will behave, when i shorten the fuselage. now teh end section looks a bit to long for me. but you did a great job on teh cockpitneck and wings! very pleased with the look of it.

edit: and wow, you got her down from 21 tons to 15?

Edited July 11, 2015 by Darth Lazarus

[Halsfury]

the Halsfury Aerospace and Laz Corp. F/A-18 Super Hornet .... soudns good to me.

have her right now in my SPH and some adjustments on the wings droped the wave drag down to 0.80.

i will test how all characteristics will behave, when i shorten the fuselage. now teh end section looks a bit to long for me. but you did a great job on teh cockpitneck and wings! very pleased with the look of it.

Haha, Halsfury & Lazarus Aerospace Corp. will be the challenge entry name when this is finished

Looking forward to seeing what you do with the back end of it

[RocketTurtle]

So I think I understand the deal with shockwaves and cross sectional area curves, but I'm still a bit confused on the others, more accurately, how to read them on the graphs, and how I want them to look, and also what I can do to improve those aspects.

[Halsfury]

Well, are you talking about the wave drag graphs or the lateral/longitudinal simulator functions?

I never build by looking at the simulators other than to check that the parameters are green or white, most of the numbers it gives you about pitch, roll and yaw rates etc should be negative, when they are, they'll show up green which means that the aircraft will return to level flight after any control inputs. This means it's stable and that you're good to go, also try testing it at different altitudes and speeds to see if you have a winner or not.

If you're talking about how to read the wave drag, cross sectional area, and pressure graphs however it's very simple.

A rocket should generally have a green graph which diverges and then stays as constant as possible all the way to the bottom of the rocket, this kind of profile is consistent with serial staged rockets and is very efficient more or less.

Aircraft are a little harder since they have plenty of protrusions.

Basically there's not really a perfect answer but it's more a compromise, ideally the green curve should ascend to a point somewhere in the middle of the airplane and then taper off towards the rear, the yellow line (measuring change in cross section) should be wavy but pretty flat, and the blue pressure curve should spike at the nose and as little as possible everywhere else.

[RocketTurtle]

Well, are you talking about the wave drag graphs or the lateral/longitudinal simulator functions?

I never build by looking at the simulators other than to check that the parameters are green or white, most of the numbers it gives you about pitch, roll and yaw rates etc should be negative, when they are, they'll show up green which means that the aircraft will return to level flight after any control inputs. This means it's stable and that you're good to go, also try testing it at different altitudes and speeds to see if you have a winner or not.

If you're talking about how to read the wave drag, cross sectional area, and pressure graphs however it's very simple.

A rocket should generally have a green graph which diverges and then stays as constant as possible all the way to the bottom of the rocket, this kind of profile is consistent with serial staged rockets and is very efficient more or less.

Aircraft are a little harder since they have plenty of protrusions.

Basically there's not really a perfect answer but it's more a compromise, ideally the green curve should ascend to a point somewhere in the middle of the airplane and then taper off towards the rear, the yellow line (measuring change in cross section) should be wavy but pretty flat, and the blue pressure curve should spike at the nose and as little as possible everywhere else.

Okay, thanks. And I'm not at my computer now, but what is the graph that shows the Cd, Cl, and the two other lines? And how do I read that?

[Halsfury]

Okay, thanks. And I'm not at my computer now, but what is the graph that shows the Cd, Cl, and the two other lines? And how do I read that?

I rarely use that feature but what you want to see is a nice smooth sine wave on those graphs with slowly decreasing amplitude (decreasing height of wave)

This indicates that the airplane will eventually return to level flight after a control input, wind gust, or stall, the yellow line I believe in those graphs represents the angle of attack of the aircraft at various points in time after the disturbance (whatever values you set), and it's absolutely vital that whichever graph line which says AoA has this sine wave look to it

Other than that it's math spaghetti as far as I'm concerned and you can often intuit a good subsonic design, As I've said before the aircraft must have a solid subsonic foundation before you start to mess around

This is what happens if you try to build a hypersonic/high supersonic airframe and then try and find a way to control it in subsonic flight.

Nature it seems always frowns on the idea of taking the last step in a journey first

Edited July 12, 2015 by Halsfury

[RocketTurtle]

I rarely use that feature but what you want to see is a nice smooth sine wave on those graphs with slowly decreasing amplitude (decreasing height of wave)

This indicates that the airplane will eventually return to level flight after a control input, wind gust, or stall, the yellow line I believe in those graphs represents the angle of attack of the aircraft at various points in time after the disturbance (whatever values you set), and it's absolutely vital that whichever graph line which says AoA has this sine wave look to it

Other than that it's math spaghetti as far as I'm concerned and you can often intuit a good subsonic design, As I've said before the aircraft must have a solid subsonic foundation before you start to mess around

This is what happens if you try to build a hypersonic/high supersonic airframe and then try and find a way to control it in subsonic flight.

https://upload.wikimedia.org/wikipedia/commons/9/90/Colour_avrocar_59.jpg

Nature it seems always frowns on the idea of taking the last step in a journey first

Yeah, building a subsonic aircraft is pretty intuitive, nothing too difficult there. I'm just sort of wondering what little designs tweaks and stuff would help. Like, what wing configuration works best? And should I have a V tail?, 2 vertical stabilizers or one? Things like that.

And I've seen that last picture and it made me wonder; who was playing Kerbal all night?

[Coga19000]

Just something I noticed from page 3:

*Good-looking VTOLs are exempt from any requirements.

That was a jab at the F-35, wasn't it?

[RocketTurtle]

So guys, with stock parts, is it possible to make a supermaneuverable aircraft? Along with thrust vectoring?

[tetryds]

That was a jab at the F-35, wasn't it?

Why would I do that? The F-35 is... beautiful

It was just a joke.

So guys, with stock parts, is it possible to make a supermaneuverable aircraft? Along with thrust vectoring?

It is, posible, just harder.

Wanting to have more post stall control than enough to not die is asking a bit too much though, too little gimbal.

[Halsfury]

edit: and wow, you got her down from 21 tons to 15?

Yeah basically I took a lot of fuel out and redistributed it as part of the wing change

[Halsfury]

Yeah, building a subsonic aircraft is pretty intuitive, nothing too difficult there. I'm just sort of wondering what little designs tweaks and stuff would help. Like, what wing configuration works best? And should I have a V tail?, 2 vertical stabilizers or one? Things like that.

And I've seen that last picture and it made me wonder; who was playing Kerbal all night?

Well maybe if they played KSP they wouldn't have made such a mistake with building the avrocar. Even though disk shaped craft are cool it's sufficient to know that at this time humans haven't figured out how to control enough energy to make them worthwhile, except when re-entering the atmosphere. The avrocar was an oddity because it was thought up by people during the cold war who thought that the spate of UFO incidents at the time might be Russian

The avrocar was the predecessor to modern hovercrafts so it was sort of a disguised breakthrough

https://en.wikipedia.org/wiki/Avro_Canada_VZ-9_Avrocar#Design_and_development

Also V tails are bad for aircraft which have to travel above something like mach 0.7 due to the increased aerodynamic pressure. They have only one failure mode, and that's where it all comes unglued and the remainder of the airframe enters an unrecoverable flat spin.

2 vertical stabilizers are optional, they are mainly used because the centre of pressure at high mach speeds starts to shift forwards until the aircraft swaps ends (and then likely explodes).

To counteract this 2 stabilizers might be prudent

Edited July 12, 2015 by Halsfury

[FourGreenFields]

2 vertical stabilizers are optional, they are mainly used because the centre of pressure at high mach speeds starts to shift forwards until the aircraft swaps ends (and then likely explodes).

To counteract this 2 stabilizers might be prudent

Unless you can live with a single ridiculously large tail fin ofcourse.

[Scoundrel]

If I might be permitted to make a few humble suggestions to the challenge:

1. The TWR should be greater than 1.25 (or whatever number is decided), static@SL (on the tarmac would be fine I imagine), full combat load (minus drop tanks; ordnance+ECM only), with 50% internal fuel.
   
2. The supercruise requirement as it sits is dimensionless from a battlespace perspective. The requirement should be: ability to supercruise (above mach 1) with full combat load for 40+ minutes (or whatever number is chosen) using internal fuel only. This is to ensure a proper fuel fraction for the airframe. Give .1 point per 1 or 5 or 10 minutes or whatever, over the base requirement. This point can be revised further to create a more complex formula.
   
3. The maneuver requirements are closer to the capabilities of 3rd gen aircraft, let alone 5th gen. The minimum airframe requirements should be:
   
   • 12G design load factor (15G+ for true Gen 5)
     
   • 18G ultimate load factor (some airframes will take over 30 if you can believe it)¹
     
   • 30°+/second max pitch rate (60°-75°+/second for true ACM prowess - gotta love those Turkeys!)
     
   • 25°+ AoA capability
     

[*]Supermaneuverability is currently overrated as post-cornering speed maneuvers in ACM has been rendered obsolete thanks to a combination of thrust vectoring missile motors, vastly improved all aspect seeker head gimbal ranges, and 360°helmet mounted cueing systems. It's cool for airshows and potentially useful in 1v1 WVR engagements, and even against older aircraft and weapon systems; unfortunately, post-stall ACM becomes a detriment in simulations of 1v2 and 2v2+ WVR engagements where flying using Energy Maneuverability Theory proves superior.

[*]The points for droptanks are redundant and don't reward efficiency. Rather than reward points for both supercruise endurance and fuel capacity, points should be rewarded for endurance at full load at supercruise, and for the mass of the combat load it is carrying (i.e.: 3 hours supercruise is worth X points, and every 1000kg (or whatever) carried at supercruise is worth Y points). Like point #2, this point can be revised further to create a more complex formula.

[*]Overwing missile rails and drop tanks should be allowed as there is precedence for both (just off the top of my head): the English Electric Lightning had overwing tanks, and the SEPECAT Jaguar has overwing missiles. Due to the unpleasant stimuli in the gluteus maximus caused by servicing such a setup, the points value of these stations towards points for # of stations should be halved... because someone has to represent maintenance and ordnance personnel.

[*]Even if BD armoury isn't used, there should be a requirement for Structural Pylons or some such to represent weapon stations since that adds drag.

¹Yes, people do not normally pull 30G. We're talking about the safety factor built into the airframe - this is how many G the airframe can take before breaking up.

[RocketTurtle]

Well maybe if they played KSP they wouldn't have made such a mistake with building the avrocar. Even though disk shaped craft are cool it's sufficient to know that at this time humans haven't figured out how to control enough energy to make them worthwhile, except when re-entering the atmosphere. The avrocar was an oddity because it was thought up by people during the cold war who thought that the spate of UFO incidents at the time might be Russian

The avrocar was the predecessor to modern hovercrafts so it was sort of a disguised breakthrough

https://en.wikipedia.org/wiki/Avro_Canada_VZ-9_Avrocar#Design_and_development

Also V tails are bad for aircraft which have to travel above something like mach 0.7 due to the increased aerodynamic pressure. They have only one failure mode, and that's where it all comes unglued and the remainder of the airframe enters an unrecoverable flat spin.

2 vertical stabilizers are optional, they are mainly used because the centre of pressure at high mach speeds starts to shift forwards until the aircraft swaps ends (and then likely explodes).

To counteract this 2 stabilizers might be prudent

So if V tails are bad, what was the motivation behind the design of the F-22, and the YF-23?

And yeah I remember reading about the avrocar. Interesting concept but I can't see the practicality of it.

[Scoundrel]

So if V tails are bad, what was the motivation behind the design of the F-22, and the YF-23?

The F-22 has twin vertical stabilizers, not V tails. This is a V tail:

The V tail on the YF-23 isn't quite the same as your typical V tail because the loads were spread out better over the fuselage - unfortunately the added complexity of such a design ended up biting Northrop in the posterior.

[CrisK]

If I might be permitted to make a few humble suggestions to the challenge:

1. The TWR should be greater than 1.25 (or whatever number is decided), static@SL (on the tarmac would be fine I imagine), full combat load (minus drop tanks; ordnance+ECM only), with 50% internal fuel.
   
2. The supercruise requirement as it sits is dimensionless from a battlespace perspective. The requirement should be: ability to supercruise (above mach 1) with full combat load for 40+ minutes (or whatever number is chosen) using internal fuel only. This is to ensure a proper fuel fraction for the airframe. Give .1 point per 1 or 5 or 10 minutes or whatever, over the base requirement. This point can be revised further to create a more complex formula.
   
3. The maneuver requirements are closer to the capabilities of 3rd gen aircraft, let alone 5th gen. The minimum airframe requirements should be:
   
   • 12G design load factor (15G+ for true Gen 5)
     
   • 18G ultimate load factor (some airframes will take over 30 if you can believe it)¹
     
   • 30°+/second max pitch rate (60°-75°+/second for true ACM prowess - gotta love those Turkeys!)
     
   • 25°+ AoA capability
     

[*]Supermaneuverability is currently overrated as post-cornering speed maneuvers in ACM has been rendered obsolete thanks to a combination of thrust vectoring missile motors, vastly improved all aspect seeker head gimbal ranges, and 360°helmet mounted cueing systems. It's cool for airshows and potentially useful in 1v1 WVR engagements, and even against older aircraft and weapon systems; unfortunately, post-stall ACM becomes a detriment in simulations of 1v2 and 2v2+ WVR engagements where flying using Energy Maneuverability Theory proves superior.

[*]The points for droptanks are redundant and don't reward efficiency. Rather than reward points for both supercruise endurance and fuel capacity, points should be rewarded for endurance at full load at supercruise, and for the mass of the combat load it is carrying (i.e.: 3 hours supercruise is worth X points, and every 1000kg (or whatever) carried at supercruise is worth Y points). Like point #2, this point can be revised further to create a more complex formula.

[*]Overwing missile rails and drop tanks should be allowed as there is precedence for both (just off the top of my head): the English Electric Lightning had overwing tanks, and the SEPECAT Jaguar has overwing missiles. Due to the unpleasant stimuli in the gluteus maximus caused by servicing such a setup, the points value of these stations towards points for # of stations should be halved... because someone has to represent maintenance and ordnance personnel.

[*]Even if BD armoury isn't used, there should be a requirement for Structural Pylons or some such to represent weapon stations since that adds drag.

¹Yes, people do not normally pull 30G. We're talking about the safety factor built into the airframe - this is how many G the airframe can take before breaking up.

1.25 is incredibly high for a fighter jet. They normally sit at around 1.0.

I like your second and fifth suggestions.

BDArmory is neat, but the weapons are not properly scaled to Kerbal parts.

Edit: I suggest dropping the limitations on turbojets so that we can make some fun (goofy) single engine designs.

Does anyone know of any good Mac-friendly screen capturing software? I'd like to record myself flying everyone's creations around.

You run KSP on a macbook air? I'm using a 2012 macbook pro and I'm concerned about heat generation

Thanks for the help with the wings and you're welcome in regards to the challenge. I got the idea at first because of the F-35 and just how bad and compromised it is. At first I wanted the challenge to be something along the lines of build a better aircraft than Boeing can.

But then I increased the difficulty by insisting that you build a real 5th gen fighter

There's an intrinsic problem to this challenge: what constitutes a 5th gen fighter? A larger multirole fighter like the Eurofighter or Rafale, or a something a bit smaller like the F-35 or Saab Gripen?

The Rafale replica that I built is arguably a much better multirole fighter than the flying bathtub/Boeing X-32 replica that I built, but I entered the X-32 into the challenge because it's a fun little...

I run KSP at half quality, windowed, and with minimal mods.

KJR doesnt make things indestructible. They still come apart, just at more realistic levels. If I take my XF-150A and throw it into a 12G turn at mach 1.2 at low level the air pressure will turn it into confetti pretty quickly.

If you attach something to a weak point structurally it doesn't matter what you use it will still break.

Hodo, I found out that FAR's Flight Assistance toggles were causing your plane to go wild. When I turn the flight assistance toggles off, the 150 flies perfectly.

Edited July 12, 2015 by CrisK

[FourGreenFields]

So if V tails are bad, what was the motivation behind the design of the F-22, and the YF-23?

If they have enough seperation between them I don't think that the 2 V-tail-wings are going to interfere much with each other. Only if they're both attached at the same place, like in Scoundrel's picture.

[Hodo]

Hodo, I found out that FAR's Flight Assistance toggles were causing your plane to go wild. When I turn the flight assistance toggles off, the 150 flies perfectly.

Yeah I never use the FAR Flight Assistance toggles. I dont even design my aircraft with them in mind. I use the PID Tuner plugin most of the time but dont design for it.

And RocketTurtle my XF-150A is a true V tail design.

[Halsfury]

Yeah when I said V tail I was talking about something like scoundrel's pic

It really becomes a problem because having only 2 control surfaces like that does give lower drag but they each have more strain placed on them since they have to deflect more to achieve the same result as a traditional elevator.

As you approach the speed of sound and pressure drag starts to be an issue, and aerodynamic pressure scales up, the more likely that inputs will cause flex in the structure. This might lead to a stiffening of controls (which can be fatal) or the total catastrophic failure of the elevator and stabilizer assembly (which is invariably fatal)

the YF-22 doesn't have a V tail it just has 2 vertical stabilizers, this distributes the load adequately for a mach 2 capable jet.

Also @ Scoundrel, I'll consider that but I wouldn't discount super manoeuvre as unimportant, in fact for all that stuff about thrust vectoring sidewinders, there is no doubt always going to be a good counter measure. A fighter can't live by it's machine guns in a modern world but unlike a missile the guidance for a bullet can be done internally and can't be tampered with. This plus the fact that there is a long history of people going back to 1918 saying "dogfighting would be a thing of the past if aircraft reach speeds of just X mph" or "long range missiles will end dogfighting" or missiles with thrust vectoring.

Basically nobody knows what 5th generation combat really looks like so many approaches should be rewarded so long as they fall within certain speed requirements. Also I don't want to limit participants

Edited July 13, 2015 by Halsfury
Named wrong OP for suggestions due to extensive quote

[tetryds]

http://forum.kerbalspaceprogram.com/threads/20451-1-0-4-Ferram-Aerospace-Research-v0-15-4-Glauert-7-12-15?p=2075520&viewfull=1#post2075520

Time for reviews