H-20 bomber (with H-X, JH-XX)

Blitzo said:

With bombers, my shorthand has been basically that of the below three desirable traits, you can only choose two to develop a viable economically feasible bomber:
- large size (payload/range)
- VLO
- supersonic capable

The question is which two of those three desirable traits are actually worthwhile to have in a modern bomber.

For a strategic bomber, you need large size.
So the question is whether you want VLO or be supersonic capable, knowing that you cannot have both, and in the contemporary combat environment and battlespace.

I believe choosing "supersonic capable" means you may as well literally burn the money you're spending on buying it than actually developing and buying and supporting the fleet, given how completely unsurvivable a non-VLO primary combat aircraft is in this day and age (and especially the future)

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a B-1B or Tu-160 aren't conventional the way a B-52 or H-6 are. carrying all munitions internally already makes say a B-1B's RCS lower than expected from size alone. this is supported both by the fundamental physics and by a source. the reason it is being retired is due to heavy airframe use for the B-1s and high maintenance requirements of the swing wing. the role of swing wings are now obsolete and PLAAF is unlikely to waste airframe hours of strategic platforms on loitering CAS.

there's no on-off value for RCS. it's a continuous quantity. any decrease in RCS also decreases the detection distance, this is seen from the radar equation, which is continuous, and not a step function. going from 100 m2 (old school planes like B-52s, Tu-95s, H-6s) to 1 m2 (a clean Superhornet or Rafale) is low hanging fruit and decreases detection distance 3x. going from 1 m2 to 0.1 m2 is much harder in terms of deviation from a high performance aerodynamic shape and further reduces detection distance only by 1.7x.

in short my belief is that whatever the H-20 looks like, the most important feature is sufficient size and payload capacity to carry long ranged munitions internally. That determines RCS, aerodynamic shaping and engine choice. Once that is done, everything else follows.

FairAndUnbiased said:

a B-1B or Tu-160 aren't conventional the way a B-52 or H-6 are. carrying all munitions internally already makes say a B-1B's RCS lower than expected from size alone. this is supported both by the fundamental physics and by a source. the reason it is being retired is due to heavy airframe use for the B-1s and high maintenance requirements of the swing wing. the role of swing wings are now obsolete and PLAAF is unlikely to waste airframe hours of strategic platforms on loitering CAS.

there's no on-off value for RCS. it's a continuous quantity. any decrease in RCS also decreases the detection distance, this is seen from the radar equation, which is continuous, and not a step function. going from 100 m2 (old school planes like B-52s, Tu-95s, H-6s) to 1 m2 (a clean Superhornet or Rafale) is low hanging fruit and decreases detection distance 3x. going from 1 m2 to 0.1 m2 is much harder in terms of deviation from a high performance aerodynamic shape and further reduces detection distance only by 1.7x.

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I am aware that aircraft like B-1 have some RCS reduction methods for an aircraft of its size.

Note how in that post I never used the word "conventional".


Instead, what I said was "VLO" and "non-VLO".


B-1 and Tu-160 most definitely are in the "non-VLO" category. They are at best, partially "LO".

My belief is that if you are developing a clean sheet bomber intended to enter service in the mid to late 2020s (and likely going to serve at least 3-4 decades into the future) then you would be idiotic to develop an aircraft that is "non-VLO".

Then the question is whether you want it to be large or not (i.e. a strategic bomber). If you do, then your only option is to go for VLO that is subsonic.

If you want a smaller theater bomber, then you might be able to go for a VLO bomber that is also supersonic capable.

A bomber that is VLO... AND large (i.e. strategic)... AND supersonic capable, is likely to be so expensive and complex that it is not economically viable.

Blitzo said:

I am aware that aircraft like B-1 have some RCS reduction methods for an aircraft of its size.

Note how in that post I never used the word "conventional".


Instead, what I said was "VLO" and "non-VLO".


B-1 and Tu-160 most definitely are in the "non-VLO" category. They are at best, partially "LO".

My belief is that if you are developing a clean sheet strategic bomber intended to enter service in the mid to late 2020s (and likely going to serve at least 3-4 decades into the future) then you would be idiotic to develop an aircraft that is "non-VLO".

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they were designed without too much consideration for RCS. all they have is putting munitions internally and serpentine intakes (for the B-1). low hanging fruit. otherwise they had no further consideration for RCS: non-flush engine pods, swing wing mechanism, no RAM, no additional shaping i.e. still have large vertical stabilizer and a T tail to boot.

I understand there's no small changes in aerodynamics but these are solvable with common design changes used by VLO fighters all the time that are compatible with high performance aerodynamic shaping: engines inside fuselage, delta canard functionally substituting swing wing, use of RAM, eliminating T tails/perpendicular vertical stabilizer.

basically I don't see an unresolvable conflict between VLO and high performance aerodynamic shaping.

FairAndUnbiased said:

they were designed without too much consideration for RCS. all they have is putting munitions internally and serpentine intakes (for the B-1). low hanging fruit. otherwise they had no further consideration for RCS: non-flush engine pods, swing wing mechanism, no RAM, no additional shaping i.e. still have large vertical stabilizer and a T tail to boot.

I understand there's no small changes in aerodynamics but these are solvable with common design changes used by VLO fighters all the time that are compatible with high performance aerodynamic shaping: engines inside fuselage, delta canard functionally substituting swing wing, use of RAM, eliminating T tails/perpendicular vertical stabilizer.

basically I don't see an unresolvable conflict between VLO and high performance aerodynamic shaping.

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There's certainly no inherent unresolvable conflict, if you have lots and lots and lots of money, with a very, very very high tolerance for risk and for delays.


As it stands, trying to develop a strategic bomber sized aircraft that is VLO, as well as supersonic capable, is just too exotic and not worth the money and risk. Of those various benchmarks being supersonic capable is the least important and the most overrated.


It's not a surprise that basically everyone in the strategic bomber market are going for VLO subsonic flying wings.

Blitzo said:

There's certainly no inherent unresolvable conflict, if you have lots and lots and lots of money, with a very, very very high tolerance for risk and for delays.


As it stands, trying to develop a strategic bomber sized aircraft that is VLO, as well as supersonic capable, is just too exotic and not worth the money and risk. Of those various benchmarks being supersonic capable is the least important and the most overrated.


It's not a surprise that basically everyone in the strategic bomber market are going for VLO subsonic flying wings.

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I'm not sure how you are quantifying the risk. the bottom line for a bad conventional layout plane is something that flies but just with poor VLO characteristics. the bottom line for a flying wing is something that is not only not VLO but also can't even fly. flying wing is not only inherently unstable in all 3 axes (unlike fighters which are neutrally stable and not in all 3 axes - see F-16) but also difficult to stabilize.

3 axis unstable designs with no prior experience are risky. they are risky to design because it is far more difficult to wind tunnel model 3 axes of instability that requires constant FBW correction, than 1 axis of neutral stability. Based on my understanding, for that case you basically need FBW already finished when you do aerodynamic shape testing, rather than being allowed to somewhat separate aerodynamic shaping development from FBW development.

FairAndUnbiased said:

I'm not sure how you are quantifying the risk. the bottom line for a bad conventional layout plane is something that flies but just with poor VLO characteristics. the bottom line for a flying wing is something that is not only not VLO but also can't even fly. flying wing is not only inherently unstable in all 3 axes (unlike fighters which are neutrally stable and not in all 3 axes - see F-16) but also difficult to stabilize.

3 axis unstable designs with no prior experience are risky. they are risky to design because it is far more difficult to wind tunnel model 3 axes of instability that requires constant FBW correction, than 1 axis of neutral stability. Based on my understanding, for that case you basically need FBW already finished when you do aerodynamic shape testing, rather than being allowed to somewhat separate aerodynamic shaping development from FBW development.

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Developmental risk.

Developing a strategic bomber with a MTOW of 150-200t that is VLO is already a very complex undertaking.
Demanding that it be supersonic capable as part of its regular mission set is going to add much more developmental complexity, developmental risk, and likelihood of delays and cost overruns.


Pursuing supersonic capability in a VLO strategic bomber currently just not worth it.

As I said -- there is a reason why all the nations who are developing strategic bombers are looking at VLO subsonic flying wings.

Blitzo said:

Developmental risk.

Developing a strategic bomber with a MTOW of 150-200t that is VLO is already a very complex undertaking.
Demanding that it be supersonic capable as part of its regular mission set is going to add much more developmental complexity, developmental risk, and likelihood of delays and cost overruns.


Pursuing supersonic capability in a VLO strategic bomber currently just not worth it.

As I said -- there is a reason why all the nations who are developing strategic bombers are looking at VLO subsonic flying wings.

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@FairAndUnbiased

Yes.

A H-20 which can go supersonic will have:

1. Reduced Range
2. Reduced Stealth
3. Reduced Payload
4. Additional Cost, development risk and delays

It's not worth the tradeoff.

AndrewS said:

@FairAndUnbiased

Yes.

A H-20 which can go supersonic will have:

1. Reduced Range
2. Reduced Stealth
3. Reduced Payload
4. Additional Cost, development risk and delays

It's not worth the tradeoff.

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Will it? I don't know, you don't either. An assertion of a final result isn't a fact, it is a conjecture. Note I never made conjectures about final costs, RCS, or payload, only about aerodynamic shaping.

Here are facts:

1. flying wing is inherently unstable in multiple axes, adding to developmental risk and delay in multiple ways. A conventional layout plane does not suffer multiple axis instability, only single axis neutral stability at worst and for planes that don't need maneuverability, all axis stability. This makes it easy to test and design.

2. Conventional layout with RCS reduction features is compatible with high performance aerodynamic shaping. We have not yet seen a high performance flying wing.

3. you can get very high RCS reduction simply by deleting high RCS design features such as corner retroreflectors and external munitions. They have already been applied to existing aircraft. This concept has been proven with every 5th gen fighter in existence.

FairAndUnbiased said:

Will it? I don't know, you don't either. An assertion of a final result isn't a fact, it is a conjecture. Note I never made conjectures about final costs, RCS, or payload, only about aerodynamic shaping.

Here are facts:

1. flying wing is inherently unstable in multiple axes, adding to developmental risk and delay in multiple ways. A conventional layout plane does not suffer multiple axis instability, only single axis neutral stability at worst and for planes that don't need maneuverability, all axis stability. This makes it easy to test and design.

2. Conventional layout with RCS reduction features is compatible with high performance aerodynamic shaping. We have not yet seen a high performance flying wing.

3. you can get very high RCS reduction simply by deleting high RCS design features such as corner retroreflectors and external munitions. They have already been applied to existing aircraft. This concept has been proven with every 5th gen fighter in existence.

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What myself and what AndrewS are talking about is more than just aerodynamic shaping -- it is about developmental cost, developmental risk and procurement and operating costs of the sort of aircraft you are describing (a large strategic bomber that is both VLO and supersonic capable), and the challenges that such a project and program will face in all of those domains.

Just because something is technologically or technically feasible does not make it a sensible weapons platform to develop and procure.

Blitzo said:

What myself and what AndrewS are talking about is more than just aerodynamic shaping -- it is about developmental cost, developmental risk and procurement and operating costs of the sort of aircraft you are describing (a large strategic bomber that is both VLO and supersonic capable), and the challenges that such a project and program will face in all of those domains.

Just because something is technologically or technically feasible does not make it a sensible weapons platform to develop and procure.

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But you don't know that. The existing evidence is that the majority of VLO aircraft are conventional layout with high aerodynamic performance meaning tight turn radius, high L/D and high T/W.

The aerodynamic shaping is also the most important part of an aircraft. It determines the choice of everything else and is set in stone. It is why flying bricks are bad. If aerodynamic shaping was irrelevant then a sphere has minimal RCS but obviously a sphere with a turbofan attached to it isn't a good shape. Subcomponents can be changed but not the airframe.

The majority of VLO aircraft use conventional shaping with RCS lowering features which reduces RCS by ~100 fold vs equal dimensioned aircraft with no RCS consideration. See F-15 vs F-22 or J-20 vs J-16 RCS comparisons.

A conventional layout also doesn't necessarily have to be supersonic. It could just have lower engine requirements because it doesn't fly like a brick.