Design Challenge: Lightweight Multirole Fighter (LMF)

[zen]

Btw, wingtip weapons pods are shown in "Flying Wings and Radical Things" page 256

I've drafted wingtip-pods which can accommodate short range AAM's.
Those pods are in addition to the main bay ( 4x AIM-120) and are intended to be detachable/ interchangeable. The missile would be deployed with a "trapeze launcher", similar to the on used in the F-22's side bays.
Furthermore, those wingtip-pods could also be utilized to house EW- or ISR-equipment, or may be used as additional fuel tanks.

What do you guys think?

Depicted: AIM-132 ASRAAM
Length: 2,9 m
Diameter: 0,166 m
Wingspan: 0,45 m

View attachment 673229View attachment 673230View attachment 673231View attachment 673232

Of all the SRAAM options to depict, you choose the one that doesn't need to lock on before launch due to using a datalink and strap down INS.
If you where using a CAMM development, it wouldn't even need to eject out the side.....

 

[VTOLicious]

Btw, wingtip weapons pods are shown in "Flying Wings and Radical Things" page 256

I've drafted wingtip-pods which can accommodate short range AAM's.
Those pods are in addition to the main bay ( 4x AIM-120) and are intended to be detachable/ interchangeable. The missile would be deployed with a "trapeze launcher", similar to the on used in the F-22's side bays.
Furthermore, those wingtip-pods could also be utilized to house EW- or ISR-equipment, or may be used as additional fuel tanks.

What do you guys think?

Depicted: AIM-132 ASRAAM
Length: 2,9 m
Diameter: 0,166 m
Wingspan: 0,45 m

View attachment 673229View attachment 673230View attachment 673231View attachment 673232

Of all the SRAAM options to depict, you choose the one that doesn't need to lock on before launch due to using a datalink and strap down INS.
If you where using a CAMM development, it wouldn't even need to eject out the side.....

IRIS-T ?

 

[VTOLicious]

Here we go, the FAR-21 Griffin is born. One can guess what FAR stands for

When will you submit the drawing?

An almost perfect little stealth fighter

 

[paralay]

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[riggerrob]

That second seat may be too expensive for smaller operators.
How many are willing to invest in flight simulators that are accurate enough to replace most of the real flight time required to attain basic skills and retain those skills?

 

[paralay]

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[VTOLicious]

Those numbers are not accurate by the way. In particular the frontal area and volume.

 

[VTOLicious]

...

 

[paralay]

,

 

[helmutkohl]

what do yall think would be the optimal location of the intakes for a small stealthy fighter? on the sides like usual? a chin intake? or a dorsal intake?

 

[paralay]

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[VTOLicious]

It's natural. The accuracy of the drawing and its measurement cannot be more accurate than a 3D model.
Nevertheless, it is sufficient to obtain characteristics in the "first approximation"

I'm just wondering why you use the inaccurate numbers when there are obviously more accurate ones already existing.

 

[VTOLicious]

what do yall think would be the optimal location of the intakes for a small stealthy fighter? on the sides like usual? a chin intake? or a dorsal intake?

Optimal? There is no definitive answer to that. It is all dependent on the requirements!
Otherwise all combat aircraft would have the same "optimal" intake layout.

 

[paralay]

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[UpForce]

An almost perfect little stealth fighter

It came out very well, I think the design benefits from the constraints you set.

Choosing Boeing's "Enclosed Weapons Pod" as a starting point was especially inspired and I'm glad you stuck to your guns (or missiles, in this case) on that. I might have a few niggles with some form factors here and there but those are predominantly matters of taste and I'd much rather have diversity of thought than everything conforming to my prejudices.

Do you intend to explore the design further still? I'm half worried though that in that case some actual projects will soon begin to bear an uncanny resemblance to FAR-21 ...

 

[paralay]

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[VTOLicious]

Comparison with other fighters. Radar in the table from JAS-39
There is no complete data for the Korean fighter KF-21, because there is no drawing

That's an interesting comparison table and I appreciate your effort!
However, I don't really know how to judge these values and how credible this comparison really is.

For example, the value "total combat effectiveness"
FC1 and Tejas are both almost on par with JAS39. As said, I don't know how these values are calculated and what "total combat effectiveness" really means , but I have a hard time to believe that JAS39 isn't better than the two.

 

[VTOLicious]

I'm just wondering why you use the inaccurate numbers when there are obviously more accurate ones already existing.

I'll put this data in a table and compare your project with other fighters. The characteristics of other fighters were obtained by such an "inaccurate method", I will not deviate from the chosen order so as not to violate the reporting

What are the characteristics of the radar?

 

[VTOLicious]

There is no complete data for the Korean fighter KF-21, because there is no drawing

I couldn't find anything better... Source: https://www.koreaaero.com/EN/data_file/BROCUERE/2021_KAI_brochure_ENG_210528.pdf

 

[paralay]

,

 

[VTOLicious]

An almost perfect little stealth fighter

It came out very well, I think the design benefits from the constraints you set.

Choosing Boeing's "Enclosed Weapons Pod" as a starting point was especially inspired and I'm glad you stuck to your guns (or missiles, in this case) on that. I might have a few niggles with some form factors here and there but those are predominantly matters of taste and I'd much rather have diversity of thought than everything conforming to my prejudices.

Thank you!

Do you intend to explore the design further still? I'm half worried though that in that case some actual projects will soon begin to bear an uncanny resemblance to FAR-21 ...

That wouldn't bother me at all

 

[VTOLicious]

Another option for the internal carriage of SRAAM's would be conformal pods above the air inlets. Similar to the bump on the F-35A, which houses the gatling gun.
View attachment 673301
Such a conformal pod may provide a solution for an optional gun as well, but I would need to free up some internal space for the ammunition.

Either... or...

Wing Tip Pods (WTP)


Conformal Body Pods (CBP)


I tend towards Wing Tip Pods, because aerodynamics of the fuselage is not affected, the missile's motor plume is far away from the fuselage / canopy / tail surface and last but not least weapons loading is much easier. Hard to tell which one would compromise RCS more. However, both are intended as add-ons.

 

[Pioneer]

Congratulations VTOLicious, very impressive!!

I only have one immediate concern, which is the lack of rear visibility of your cockpit/canopy arrangement.

Regards
Pioneer

Thank you!

I assume DAS+HMD provides sufficient situational awareness:

View: https://www.youtube.com/watch?v=e1NrFZddihQ

Yes true, but In all due respect VTOLicious, I think history has taught us again and again the importance of the Eye ball Mk.I in air combat.

Regards
Pioneer

 

[paralay]

,

 

[VTOLicious]

Evaluation of total combat effectiveness:

LMF - 2.05
KF-21 - 2.16
JAS-39 - 1.55
LTS - 2.92

Thus, the expected efficiency of the "light fighter" LMF is quite high and is almost at the level of the "medium fighter" KF-21

Not bad at all

The comparison with KF-21 is especially interesting, because the same engine is used. Did you assume a future version of KF-21, which features an internal weapons bay?
Btw, is it supposed to carry 4 or 6 medium range missiles internally?

 

[paralay]

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[UpForce]

Either... or...

My "hot take" would be neither. Since this is a purposefully minimized jet I, at least, see it as a "pack hunter" wherein capabilities are distributed among however many there are for a mission. Have you considered what kinds of combinations of missiles can fit internally? Four AMRAAMs for a fighter in this class is already a lot.

On the other hand smaller jets tend to have a stealthiness advantage WVR wherein the utility of SRAAMs might be proportionally greater; still, my first instinct wouldn't be to start making compromises in flight characteristics to accommodate more missiles per fighter. Being whimsical, could you fit something within the "area rule bump"?

 

[VTOLicious]

Either... or...

...Being whimsical, could you fit something within the "area rule bump"?

Haha, I'm already exploring the option to fit a single IRIS-T in the bump above the engine. The last resort so to say, just for self defence.

It basically fits, I just need to expand the bump a little bit more. However, the biggest concern is access to the bay for loading it.
I thought to make use of a "trapeze launcher" that pivots towards the rear, so that the missile can be slid onto the launch rail from the rear end. But I need to figure that out in detail.

I'll post some pics soon

Edit: F-22's "trapeze launcher" added:

 

[Magnum_Force]

How big are those wingtip pods? If you stuck to ASRAAM, I reckon you could get up to 3 of them in there if you staggered the missiles horizontally so the rear fins didn't collide. Apparently the diameter of an ASRAAM is 166mm, so if you say 400mm diameter for the wingtip pod and have it open clamshell style, I think it might work?

 

[zen]

How big are those wingtip pods? If you stuck to ASRAAM, I reckon you could get up to 3 of them in there if you staggered the missiles horizontally so the rear fins didn't collide. Apparently the diameter of an ASRAAM is 166mm, so if you say 400mm diameter for the wingtip pod and have it open clamshell style, I think it might work?

If they had folding fins, you could fire them out like the earlier SRAAM and would only need openings front and rear in the pod.

 

[Magnum_Force]

If they had folding fins, you could fire them out like the earlier SRAAM and would only need openings front and rear in the pod.

That could work also, however you'd still probably want doors for the front and back that could open/close to preserve LO.
Such a mechanism could even work with a horizontally staggered ASRAAM arrangement, the drawback being that the missiles would need to fire in the order they are staggered; if you had a dud it would mean any missiles behind it would be stuck. Another drawback is the blast from the rocket motor would engulf the other missiles in the pod, which may or may not be a problem.

 

[zen]

If folding fins done right, no impingement on staggered storage.
If using CAMM technologies, launch might even be 'cold' using gas pressure....though it's tricky to achieve that in this case.

Upside of ASRAAM/CAMM is target location delivered without sensor lock-on. Datalink can correct after launch.
Upshot is launch doesn't require aircraft to change direction.

I have speculated that there ought to be a smaller modern ASRAAM type closer to SRAAM or later VSRAAM.
I dubbed CAMM-SR (short range). Investment in that for self defence could yield large production runs.
Something like that is offered for development for Project Tempest.

 

[VTOLicious]

Without a doubt, fins are a headache for internal weapon storage. But it is a matter of fact that currently no SRAAM is available with folding fins.

This design exercise aims to proof the feasibility of an LMF (on a conceptual level). All considerations are based on currently available technologies, systems, products, etc., and implemented in combat aircraft which already in service (or at least at prototype stage).

It's apparent that this approach will lead to a rather conservative / less capable design in comparison to a highly speculative design, mainly based on unproven technology.
But most importantly: This approach ensures that feasibility is beyond doubt! Otherwise we will end up in endless discussions on the credibility of the design.

Edit: I would rather discuss the necessity of dedicated IWB's for SRAAM's. E.g. F-35 doesn't have one. And the B/C model doesn't even have an internal gun.

 

[Magnum_Force]

I think most people would agree that most stealth fighters are a little lacking in IWB capacity, especially compared to most 4 gen fighters.
Looking at your design, I would be tempted to cram another identical IWB immediately behind the current one, but that would lengthen the fuselage somewhat and also throw boff the centre of gravity.

 

[VTOLicious]

I think most people would agree that most stealth fighters are a little lacking in IWB capacity, especially compared to most 4 gen fighters.
Looking at your design, I would be tempted to cram another identical IWB immediately behind the current one, but that would lengthen the fuselage somewhat and also throw boff the centre of gravity.

Such a long bay would only be applicable to
a twin engine layout, as seen on the Su-57.

 

[Magnum_Force]

Looking back at your drawings, you are right; I didn't appreciate how deep the IWB is. Initially I thought it was only slightly taller than the bottom of the intake, but it extends all the way to the top of it.

 

[VTOLicious]

Looking back at your drawings, you are right; I didn't appreciate how deep the IWB is. Initially I thought it was only slightly taller than the bottom of the intake, but it extends all the way to the top of it.

Please keep in mind that the design of FAR-21's IWB is based on the Boeing's Enclosed Weapons Pod (proposed for the Advanced Super Hornet). It supports a broad array of air-to-air and air-to-surface weapons, as advertised by Boeing, or anything else that fits (e.g. Meteor missiles).



That's most probably the maximum internal load one can get out of a lightweight fighter, powered by a single F414 engine.
And that's quite a lot, if you compare it to the internal load of medium- and heavyweight stealth fighters.

 

[VTOLicious]

airframe weight without chassis 3638,728 kg
chassis weight 286,497 kg
airframe weight with chassis 3925,225 kg
equipment weight 900.42 kg
empty weight 8185,633 kg
curb weight 8435,633 kg
fuel weight 3136 kg
take-off weight normal In-In, 50% fuel 10749,65 kg
maximum In-In, 100% fuel 12963,67 kg
maximum take-off weight 15671,67 kg
distillation weight without tanks 11671,67 kg
landing weight 8692,422 kg

the mass of the normal combat load is 646 kg
the mass of the maximum combat load is 4000 kg

flight range without external tanks 1922 km

@paralay
I had a look at your table, but I have problems to figure out which items are part of your empty weight calculation.
Can you elaborate?

Empty weight = 8185 kg
Airframe weight (3639 kg) + chassis (286 kg) + equipment weight (900 kg) + engine weight (1107 kg) + radar (215 kg) = 6147 kg

What are the missing items? ECS, APU, fuel system, etc.? What is part of the equipment weight (900 kg)?

 

[paralay]

,

 

[VTOLicious]

there is another table for this, but it is in Russian

Яндекс

Найдётся всё

disk.yandex.ru

It seems I need to learn Russian soon