Global 6th Generation Fighter Aircraft Projects

[Bhartiya Sainik]

I believe s ducts are a no brainer design at this point. The s ducts on the F-35 curve really hard so I don’t see any issues with finding the space.

T

Ducts seem as long or slightly longer than f22's ducts
This j50 looked similar in size to the flanker that was the chase aircraft flying together with it.
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With modern CAD S/w it might have been taken care of. We can twist the ducts while maintaining its cross section area. Time will tell definitely. Some day, like J-20, all other jets also have to be revealed from close distance.
For common people like us it can actually be a big headache to imagine in 2D, unless we know how to use 3D CAD S/w.
Most 3D artists also make models w/o thinking too much themselves.

F-35 is 1 engined, so having a Y-duct.
Let's take F-22 as foundation reference.
If we wan't a better TE jet as per 6gen features of more capacity of weapons, fuel, new components, then it'll be bigger. So if the size/volume/weight is more & if same or more dry/wet ATWR (Airframe Thrust to Weight Ratio) needs to be maintained, then more airframe weight -> more thrust -> more air -> more area of intake, duct & inlet.
For idea, F-22's F119 Vs F-35's F-135 engines: 100cm Vs 109cm inlet dia., 116/128 KN Vs 156/191 KN dry/wet thrust. 9% more inlet dia., almost 19% more area, 10.3% more dry thrust, 22.4% more wet thrust.

There is no fixed formula b/w area of intake/duct/inlet & thrust, let's assume 1:1 ratio in increase for easy understanding. So if we fit F-22 with a bigger & 33% better engine of 156*1.33= 207.5 KN, the challenges are -
- increase air flow by 33%, means increase area of intake, duct & inlet by 33%. Inlet diameter increases by square-root(1.33) times or 15.32%.
- increase payload & range, means lengthen the jet.
- restrict airframe volume to 133%.
- restrict airframe height to that of F-22 if possible.

If the airframe expands only in width & height then it is easy to design.
If the airframe expands in all 3 XYZ axis in same ratio then also it is easy to design.
But if all 3 axis have different ratios then we have to be careful not to eceed new volume/weight.

Option 1 - stretch the airframe length only by 33%, which will need tandem IWB for extra AAMs.
Option 2 - stretch the airframe width only by 33%, which can adjust 4 more AAMs easily.
Option 3 - stretch both airframe width & length by ratio such that X*Y=1.33, like 1.1*1.2 or 10% X 20%.

Exploring option-1 1st, the fuselage width remains same, area of intake, duct & engine increased, again there are 3 sub-options:
1A - expand area in width & height by 15.32%, engine can be pushed down, but intake slightly portrudes down & out, duct above IWB is manageable.
1B - expand area in height only by 33%, engine can be pushed down, but intake portrudes down more & duct above IWB produces bump.
1C - expand area in width only by 33%, engine is pushed down, intake portrudes out sideways but manageable, duct above IWB is manageable.

I don't have 3D CAD S/w, so I put the above options 3 sub-options in approximate cross section diagrams of F-22:



So we see that increased size/volume of 1 or some components or system affects other parts & entire airframe.
The engine power, size, weight is dictating design of stealth jet if same ATWR has to be maintained.

 

[johny_baba]

ok, a noob question but since we're talking about sixth gen fighters here,

as it's known, a landing gear system takes up lots of space inside a jet, it's heavy too,

so with advancements now, is there any viable alternative to conventional landing gear and runway systems for taking off and landing?

well, VTOL is there but except Harrier Jumpjets, F-35B and to some extent, Yak-141, very few of them could see success, but it's 21st century now so...yeah?

also, what if for some forks of sixth gen fighters, landing gears are ditched and it's launched in air by ground based EMALS systems and lands using parachutes or something?

 

[randombully]

as it's known, a landing gear system takes up lots of space inside a jet, it's heavy too,

so with advancements now, is there any viable alternative to conventional landing gear and runway systems for taking off and landing?

well, VTOL is there but except Harrier Jumpjets, F-35B and to some extent, Yak-141, very few of them could see success, but it's 21st century now so...yeah?

VTOL system or any other vertical takeoff system will be lot more heavy and take up lot more space compared to landing gears, so it's opposite of what you are desiring.
Plus significantly reduced payload and range.

also, what if for some forks of sixth gen fighters, landing gears are ditched and it's launched in air by ground based EMALS systems and lands using parachutes or something

Similar thing is being done with the kratos valkarie loyal wingman drone.

View: https://youtu.be/pIU5DOPiteA?si=MQooNIgNWxodqUkg
Or this.

View: https://youtube.com/shorts/-hZiLeA6CPk?si=xAp8jTEKX7VZI8Hj

New Shots Of Stealthy XQ-58A Valkyrie Highlight Its Runway Independence

Valkyries, or future derivatives thereof, could be rapidly launched and recovered from remote forward areas, since they don't need runways.

www.twz.com

and similar ideas were tested in past too with both US and USSR

But there are certain limitations.
1, modern fighter jets are more heavy than loyal wingmans and fighter jets of past, especially 6th gen will be 30ton class.
So a lot more rockets and bigger launcher bigger rocket assested takeoff.
Now that big of a launcher and rockets will be lot of hassle to move and transport on roads, in case of destruction of runway, fighters with landing gear can land and takeoff from highways.
Rocket assisted takeoff, or even the trolley launcher system shown in first video would limit it.

2, in case of rocket assisted, the g forces will be a big problem for the pilot, even Ship based emals put high g forces on pilots and airframe(hence reducing it's life hours) these g forces will be many times greater.

3, extra modifications will need to done to fighter jets to fit the parachutes in right positions for centre of gravity( some space and weight will still be sacrifised)and extra modifications at it's bottom to touch down on ground.
3, having to refit the parachutes every time a fighter lands will delay it's preparedness, plus much higher chances of it not landing correctly and mishap happening during landing( wouldn't want it with that expensive marvel of engineering and increasing risk to pilots life)
4, winds can mess with you during landing with you having no control, could be catastrophic.( same)
5, not just landing take off is also more dangerous in both methods than conventional takeoff.


So having landing gears is just better .
The valkayrie like systems does have lot more positives than negatives when used on ships.
And that's the intended purpose of valkayrie, US marines are highly intrested in that loyal wingman.
Don't need to construct new ships having long flight decks, can be launched modifying from container ships, amphibious assault ships, is cheaper and expendable, don't need to sacrifice lots of space( that houses fighters, heli, supplies) in existing long flightdeck ships.
Etc.


For landed based aircraft, a landing gear is just better.

 

[Bhartiya Sainik]

ok, a noob question but since we're talking about sixth gen fighters here,

as it's known, a landing gear system takes up lots of space inside a jet, it's heavy too,

so with advancements now, is there any viable alternative to conventional landing gear and runway systems for taking off and landing?

well, VTOL is there but except Harrier Jumpjets, F-35B and to some extent, Yak-141, very few of them could see success, but it's 21st century now so...yeah?

also, what if for some forks of sixth gen fighters, landing gears are ditched and it's launched in air by ground based EMALS systems and lands using parachutes or something?

F-22 & F-35, from brake release, need only 8-10 seconds to leave runway.
For landing they don't need parachute like Su-3X & MiG-29, etc.
If 6gen maintains the ATWR then it'll also be able to take-off in 10s & land w/o chute.
Carrier like ground-based EMALS-CATOBAR can be implemented but it'll need few tons heavier & stronger landing gear & airframe structure. Every jet will be a naval jet by default.
Depending upon runway width, 2/3/4 jets can takeoff in formation.
Carrier takeoff & landings are actually slower than runway.
Some highway segments are being hardened for jets in emergency of airbase runways are cratered. For such segments, if a portable EMALS-CATOBAR is tried to be developed, catapult take-off would be easy but arresting a 30-45 ton jet would be a big challenge. The system has to be anchored deep into ground.
Some fighter jets like Tornado, Saab-37 Viggen have used thrust-reversing nozzles like airliners, to shorten landing.
F-15 SMTD tested flat nozzles with 2D TVC & reverser vanes, but was not implemented in any jet.

 

[randombully]

F-22 & F-35, from brake release, need only 8-10 seconds to leave runway.
For landing they don't need parachute like Su-3X & MiG-29, etc.
If 6gen maintains the ATWR then it'll also be able to take-off in 10s & land w/o chute.
Carrier like ground-based EMALS-CATOBAR can be implemented but it'll need few tons heavier & stronger landing gear & airframe structure. Every jet will be a naval jet by default.
Depending upon runway width, 2/3/4 jets can takeoff in formation.
Carrier takeoff & landings are actually slower than runway.
Some highway segments are being hardened for jets in emergency of airbase runways are cratered. For such segments, if a portable EMALS-CATOBAR is tried to be developed, catapult take-off would be easy but arresting a 30-45 ton jet would be a big challenge. The system has to be anchored deep into ground.
Some fighter jets like Tornado, Saab-37 Viggen have used thrust-reversing nozzles like airliners, to shorten landing.
F-15 SMTD tested flat nozzles with 2D TVC & reverser vanes, but was not implemented in any jet.

I think there's misunderstanding.
Emals doesn't have any significant benifit on land.
He was talking about launching jets without landing gear to save weight and space.
The emals like launch he mentioned is this "type"

View: https://youtu.be/HTT5ioStRiA?si=C548r8lta-GyUIfj

View: https://youtu.be/vDBCotsGlIQ?si=0xnIq2yIqv3qtCft

View: https://youtube.com/shorts/fZxEtyXkcMg?si=VSc7RwIwILZ6CEaO

 

[Bhartiya Sainik]

I think there's misunderstanding.
Emals doesn't have any significant benifit on land.
He was talking about launching jets without landing gear to save weight and space.
The emals like launch he mentioned is this "type"

View: https://youtu.be/HTT5ioStRiA?si=C548r8lta-GyUIfj

View: https://youtu.be/vDBCotsGlIQ?si=0xnIq2yIqv3qtCft

View: https://youtube.com/shorts/fZxEtyXkcMg?si=VSc7RwIwILZ6CEaO

Everybody knows truck-sized catapult & parachute landing for such small UAVs.
But such puny UAVs can be part of a bigger system, to be operated autonomously or from anywhere by anybody authorised, but not 6gen themselves.
So i answered w.r.t. a proper 6gen jet, manned or unmanned. Every part/feature of a jet occupies some space, even the parachute instead of which something else can be there. A jet can't belly-land. A tripod stand instead of wheel will also need space. But VTOL system is very complex & needs lot of space. So what can we expect from 6gen on this for a 30-45 ton jet? Anti-gravity UFO technology? That would need far more space.

 

[randombully]

Everybody knows truck-sized catapult & parachute landing for such small UAVs.
But such puny UAVs can be part of a bigger system, to be operated autonomously or from anywhere by anybody authorised, but not 6gen themselves.
So i answered w.r.t. a proper 6gen jet, manned or unmanned. Every part/feature of a jet occupies some space, even the parachute instead of which something else can be there. A jet can't belly-land. A tripod stand instead of wheel will also need space. But VTOL system is very complex & needs lot of space. So what can we expect from 6gen on this for a 30-45 ton jet? Anti-gravity UFO technology? That would need far more space.

Yeah, he was basically asking if similar things as done on these drones can be done for 6tg gen jets.
And yeah the answer is no.