The Gripen and the KAI T-50 both use the F-404 engine, and weigh within 3% of each other. Both are superonic, and can carry two crew. The T-7a is presumably very similar.

A Gripen costs about around $100M, a T-50 costs about around $30M, and a T-7a costs less.

Why does a Gripen costs so much?

Are the radar and radar-warning-receiver and missile rails really costing $70M?

Was the development of a Gripen so much more expensive that they need to recover $70M per plane (and is Saab profit per aircraft really $70M??????)

P.S. I understand the Gripen has lots of capabities that T-50 and T-7a does not. But what about those capabilities costs $70M per plane? Not "why would one pay extra" but "why does it cost extra to build it that way"? Because I don't think anyone believes Saab is making $70M per plane!

I think you are mixing up Gripen C and Gripen E. Gripen C uses a Volvo version of GE F404; Gripen E uses GE F414.

What is your source supporting a Gripen E cost of $100 million?

My understanding (from various sources) is that the earlier Gripen was around $60M, with the E model expected to be in the range of an F-35 at around $80M.

However the Gripen is far more capable than any of the primarily trainer aircraft you cited. The airframe is far stronger and more durable, and is designed for modern weapons and all the sensors & avionics that go with them. So not really a good comparison.

art wrote:

I think you are mixing up Gripen C and Gripen E. Gripen C uses a Volvo version of GE F404; Gripen E uses GE F414.

What is your source supporting a Gripen E cost of $100 million?

My error. I was refering to the Gripen C, which might cost just $60M.
https://www.shephardmedia.com/news/air- ... n-croatia/

But why does building a Gripen C cost $60M, and a T-50 cost like $30M?

Avatar2go wrote:

My understanding (from various sources) is that the earlier Gripen was around $60M, with the E model expected to be in the range of an F-35 at around $80M.

However the Gripen is far more capable than any of the primarily trainer aircraft you cited. The airframe is far stronger and more durable, and is designed for modern weapons and all the sensors & avionics that go with them. So not really a good comparison.

I think I was wrong, and a Gripen C costs about $60M. But does the radar and radar-warning-receivers really cost $30M?

Yes, a Gripen is more capable than a T-50. But what about a Gripen costs twice as much or more as a T-50?

1) I don't know that the Gripen is "far stronger" than a T-50. The Gripen has an empty weight of 14,991 lbs and the T-50 14,264 lbs. So it's not more structure. The Gripen has a max takeoff weight of 30,885 vs 27,117, so it cannot carry much more. (I don't know max-g loading.)

2) The FA-50 (which does cost a little more than the T-50) can also fire modern weapons (AMRAM/JDAM/etc). So I don't think that's a major cost driver.

Again, which part of building a Gripen costs twice as much as buiding a T-50 or T-7a?

Well the Gripen C is an honest mach 2 airplane and the T-50 can only do 1.5, and the T-7 is an outright dog at mach 1.2, so neither of those aircraft have to use materials that can handle mach 2 heating. That might account for some of the cost.

744SPX wrote:

Well the Gripen C is an honest mach 2 airplane and the T-50 can only do 1.5, and the T-7 is an outright dog at mach 1.2, so neither of those aircraft have to use materials that can handle mach 2 heating. That might account for some of the cost.

The Gripen C is mach-2 at high altitude only. What part of the plane do you think gets heated at altitude at Mach 2?

I don't think this is a concern, but I'm willing to be educated.

The correct answer is fewer parts allowing for reduced assembly time.

"The best part is no part. The best process is no process." - Elon Musk

The Saab Gripen program started roughly 20 years before the Korean T-50 trainer. Improved CAD design and machining allows for a reduced parts count. Less assembly time allows for a lower cost.

The Boeing T-7 has pushed this even further being nearly 20 years newer than the T-50.

Also remember the Pareto principle or the 80/20 rule. Generally developing something 80% as good only costs 20% of the price. This applies to other things like phones. This is a key design philosophy of the LM Skunk works that allowed for rapid development.

As technology is improving rapidly to make the same product built 10 years later will always be cheaper. Or for the same price the product can be better. So it very obvious why the T-7 is far more capable than the T-50 despite being cheaper. The F-35 is the perfect example of using the 80/20 rules to produce a high value fighter. They didn't aim for 100% agility, 100% range and 100% stealth. They aimed for 80% of the capability of an unlimited budget fighter and produced an excellent product.

The fighter variant of the Boeing T-7 will dominate the low end fighter market as it will have the capability of a brand new Block 70 F-16 but cost less than second hand 20 year old F-16's.

I still think that a trainer, even up-armed for combat, is not equivalent to a true combat fighter. If that were valid, we'd see them being offered as such in competitions around the world.

The Tejas is somewhat an exception as it is meant for first-line combat duty, but it significantly underperforms the Gripen. As do the others which are not intended for that purpose.

The T-7 will be interesting to see what they can do with it, if it evolves into a fighter. But I still highly doubt it will compete with an F-16. The main advantage it would bring is cost.

RJMAZ wrote:

The correct answer is fewer parts allowing for reduced assembly time.

"The best part is no part. The best process is no process." - Elon Musk

The Saab Gripen program started roughly 20 years before the Korean T-50 trainer. Improved CAD design and machining allows for a reduced parts count. Less assembly time allows for a lower cost.

The Boeing T-7 has pushed this even further being nearly 20 years newer than the T-50.
...

As technology is improving rapidly to make the same product built 10 years later will always be cheaper.

I have not noticed that an F-16 or F-15 cost twice as much as a Rafale or Typhoon, even though the second group was developed almost 40 years later. Nor does a 787 seem to cost half that of an A330, even though it's 25 years newer.

My point is that aircraft do not seem to be rapidly declining in price.

(Of course I know the newer planes are more capable, but there's not *that* much more capable.)

RJMAZ wrote:

Also remember the Pareto principle or the 80/20 rule. Generally developing something 80% as good only costs 20% of the price. This applies to other things like phones. This is a key design philosophy of the LM Skunk works that allowed for rapid development.

I might believe this is true in many areas. But in the fast-jet market, what's the thing that makes a Gripen cost twice as much as a T-50? Is the wing-spar made of twice-as-expensive material and process? Because the Gripen doesn't have a weight reduction or a load carrying advantage over the T-50.

It's not development cost, which was a super-low €1.84 billion.

I might be asking something that requires more-than-amature knowledge (including me).

I suspect it may not be valid to compare empty and takeoff weights, and conclude the airframes are structurally equivalent. As pointed out above there are materials needed for high speed flight, high g-loads, and high flight cycles at those loads.

Also at least for the T-7, the lift capability is well below the Gripen. There's not really a comparison.

Avatar2go wrote:

I suspect it may not be valid to compare empty and takeoff weights, and conclude the airframes are structurally equivalent. As pointed out above there are materials needed for high speed flight, high g-loads, and high flight cycles at those loads.

Also at least for the T-7, the lift capability is well below the Gripen. There's not really a comparison.

Agree, but it's the bet I got (but what you said is still true).

kitplane01 wrote:

744SPX wrote:

Well the Gripen C is an honest mach 2 airplane and the T-50 can only do 1.5, and the T-7 is an outright dog at mach 1.2, so neither of those aircraft have to use materials that can handle mach 2 heating. That might account for some of the cost.

The Gripen C is mach-2 at high altitude only. What part of the plane do you think gets heated at altitude at Mach 2?

I don't think this is a concern, but I'm willing to be educated.

Aerodynamic heating is most definitely a concern at altitude, especially the nose, cockpit, and wing leading edges. There are plenty of resources on this topic and many on this forum who could give the numbers. There is a very big reason why the F-35 design speed is mach 1.6 vs 2+, and that is because of the stealth coatings/materials inability to handle high mach temperatures and not because mach 2 is "unnecessary"

744SPX wrote:

that is because of the stealth coatings/materials inability to handle high mach temperatures and not because mach 2 is "unnecessary"

Not only the stealth coating, but the thermo property of the composite material of the skin itself.

Ironically, for an aluminum skin, even though it does not handle skin temperature above 250F well, the thermal conductivity pulls the heat from the high temperature at any hot spot.

Even though the F-35 skin high temperature composite has a theoretical operating temperature of 350F or there about, the low thermal conductivity of the composite keeps the heat at the surface and exacerbate the heat concentration at the furnace.

bt

kitplane01 wrote:

I have not noticed that an F-16 or F-15 cost twice as much as a Rafale or Typhoon, even though the second group was developed almost 40 years later.

Firstly the F-16 first flew in 1974 and the Eurofighter first flew in 1994. That is not 40 years.

Secondly I said "Improved CAD design and machining allows for a reduced parts count" The F-15 started development in the 1960's so you are comparing fighters before they were designed in CAD.

kitplane01 wrote:

Nor does a 787 seem to cost half that of an A330, even though it's 25 years newer

The 787 cost would only be lower if they aimed for the same performance as the A330. Boeing instead aimed for similar cost but much better performance than the A330. A 5% fuel burn advantage is massive in commercial aviation. It allows for total sales dominance.

kitplane01 wrote:

My point is that aircraft do not seem to be rapidly declining in price.

(Of course I know the newer planes are more capable, but there's not *that* much more capable.)

They are rapidly declining in cost for the same performance. With price being the same it allows for significantly improved performance. We are talking 100:1 kill ratio that *is* much more capable.

The latest F/A-50 with its little AESA and AMRAAM would easily have a 100:1 kill ratio against a 1970's F-16 that was Sidewinder only. Similar market and similar price in today's dollars.

quote="kitplane01"]I might believe this is true in many areas. But in the fast-jet market, what's the thing that makes a Gripen cost twice as much as a T-50? Is the wing-spar made of twice-as-expensive material and process? [/quote]
You can have the same size jigsaw puzzle but one has much more pieces.

RJMAZ wrote:

The F-15 started development in the 1960's so you are comparing fighters before they were designed in CAD.

Just to be clear though, the latest iteration(s) of the F-15 is 100% CAD by necessity in order to incorporate the latest manufacturing technique to reduce cost.

bt

744SPX wrote:

kitplane01 wrote:

744SPX wrote:

Well the Gripen C is an honest mach 2 airplane and the T-50 can only do 1.5, and the T-7 is an outright dog at mach 1.2, so neither of those aircraft have to use materials that can handle mach 2 heating. That might account for some of the cost.

The Gripen C is mach-2 at high altitude only. What part of the plane do you think gets heated at altitude at Mach 2?

I don't think this is a concern, but I'm willing to be educated.

Aerodynamic heating is most definitely a concern at altitude, especially the nose, cockpit, and wing leading edges. There are plenty of resources on this topic and many on this forum who could give the numbers. There is a very big reason why the F-35 design speed is mach 1.6 vs 2+, and that is because of the stealth coatings/materials inability to handle high mach temperatures and not because mach 2 is "unnecessary"

I was under the strong impression that non-stealthy modern jet fighters use composite material for wings and jet inlets, including leading edges. Is this false?

(BTW, the obvious-to-me Google searches don't reveal things like leading edge material, nor tempature of leading edges. So if you have on handing, I'm interested.)

bikerthai wrote:

744SPX wrote:

that is because of the stealth coatings/materials inability to handle high mach temperatures and not because mach 2 is "unnecessary"

Not only the stealth coating, but the thermo property of the composite material of the skin itself.

Ironically, for an aluminum skin, even though it does not handle skin temperature above 250F well, the thermal conductivity pulls the heat from the high temperature at any hot spot.

Even though the F-35 skin high temperature composite has a theoretical operating temperature of 350F or there about, the low thermal conductivity of the composite keeps the heat at the surface and exacerbate the heat concentration at the furnace.

bt

https://www.defensenews.com/air/2019/06 ... h-coating/

"The deficiency, first reported by Defense News in 2019, means that at extremely high altitudes, the U.S. Navy’s and Marine Corps’ versions of the F-35 jet can only fly at supersonic speeds for short bursts of time before there is a risk of structural damage and loss of stealth capability ... Both deficiencies were first observed in late 2011 following flutter tests where the F-35B and F-35C both flew at speeds of Mach 1.3 and Mach 1.4. During a post-flight inspection in November 2011, it was discovered the F-35B sustained “bubbling [and] blistering” of the stealth coating on both the right and left sides of the horizontal tail and the tail boom."

https://nationalinterest.org/blog/buzz/ ... ems-131102
"Since the incident, the Marines have instituted a policy requiring F-35B pilots not to engage afterburners for more than eighty seconds cumulatively at Mach 1.3, or forty seconds at Mach 1.4. Navy F-35C pilots have fifty seconds at Mach 1.3 to ration. ...
To “reset” the afterburner allowance, they must then allow three minutes non-afterburning flight for the tail area to cool down to avert damage"

Why does the F-35A not have the same problem?

And BTW, I don't think the problem is aerodynamic heating. Its heat from the afterburner.

My guess is the EW system. 5 GaN AESA jammer transmitters sounds expensive.

https://www.saab.com/newsroom/stories/2 ... f-gripen-e



Also not sure if the trainers have inflight refueling capability, IRST, datalink capability.

kitplane01 wrote:

"Since the incident, the Marines have instituted a policy requiring F-35B pilots not to engage afterburners for more than eighty seconds cumulatively at Mach 1.3, or forty seconds at Mach 1.4. Navy F-35C pilots have fifty seconds at Mach 1.3 to ration. ...
To “reset” the afterburner allowance, they must then allow three minutes non-afterburning flight for the tail area to cool down to avert damage"

Why does the F-35A not have the same problem?

And BTW, I don't think the problem is aerodynamic heating. Its heat from the afterburner.

Yes it is heating from the afterburner.

If you put 3,000kg of fuel and a couple of missiles into all three versions then the F-35A is much lighter. Drag is highly relative to the flying weight so the F-35A will have less drag. The F-35A will be able to fly faster at any given thrust setting. The Mach 1.6 max operational speed limit will be hit before the afterburner gets a chance to heat up rear fuselage of the F-35A.

kitplane01 wrote:

short bursts of time before there is a risk of structural damage and loss of stealth capability

Yup, the stealth coating would be the weakest link. But structural damage noted is what I was thinking.

Not sure, but just because they call it after "burner allowance" it does not involve aerodynamic heating cause by excessive speed when using afterburners.

For the commercial side we insulate the nacelles to prevent the engine heat from damaging the composite nacelles. You would think if engine heat is a problem, they would do the same.

But if you were to look at the F-22 and F-15 max speed, the difference isn't that much, so the composite design holds up pretty well.

Note that the high tempemperatue composite used by the F-22 and F-35 are nasty stuff and more difficult to fabricate than the epoxy system typically used on commercial airliners.

bt

bikerthai wrote:

kitplane01 wrote:

short bursts of time before there is a risk of structural damage and loss of stealth capability

Not sure, but just because they call it after "burner allowance" it does not involve aerodynamic heating cause by excessive speed when using afterburners.
bt

They call it "afterburner allowance". They limit time in afterburner. They don't limit time at high speed.

Climb high. Start the afterburner. Get to Mach 1.6. Start the clock. Turn off the afterburer and go into a dive. Stop the clock. Continue the dive maintaining speed. The clock does not run.

kitplane01 wrote:

Climb high. Start the afterburner. Get to Mach 1.6. Start the clock. Turn off the afterburer and go into a dive. Stop the clock. Continue the dive maintaining speed. The clock does not run.

This would be done why?

On the F-35 afterburner limitation, a couple points:

1. The restriction is related to excessive radiative heating of the tail section during afterburner, under conditions where the density of air flowing over the surfaces is not sufficient for convective cooling, relative to friction heating. This leads to a net positive heat flow with temperature building up in the tail over time, which can blister the coatings and materials. Thus the restriction.

2. It's not a combat restriction, it's meant to limit the cost of repairing the tail surface coatings and materials. Those costs are needless outside of combat.

3. Although the F-35 is not rated for supercruise, pilots have stated that the F-35 can supercruise at Mach 1.2 in some conditions, for a distance of 150 miles or so. The restriction there is heating within the weapons bays while operating for an extended period at full military power. They have been working on mitigating that issue by moving some sensitive electronics out of the bays. At the time this was stated, the solution was to slow and open the bay doors to cool down. I'm sure they have progressed since then.

Important to understand that the F-35 packs a tremendous amount of power into a small airframe. Even the best engines will dissipate 40% of their combustion energy as heat, rising to 70% or more on afterburner. Additionally the F-35 uses the tail sections to shield the engine IR & RCS signatures from many aspects, thus it has greater exposure.

So thermal management & materials are huge components of the design. Another differentiator of cost.

Does the Raptor have a similar limitation on 'burner time'?

889091 wrote:

Does the Raptor have a similar limitation on 'burner time'?

Not that I am aware of, but I believe it uses different coatings and materials compared to the F-35 as its designed for sustained supersonic speeds where the F-35 does not have that built-in requirement.

All the more amazing that the (essentially) all aluminum B-58, designed and built in the 1950's, could cruise at mach 2+ while carrying a full external weapons load until it ran out of fuel.
There is a very real price to pay for stealth coatings and materials.

744SPX wrote:

All the more amazing that the (essentially) all aluminum B-58, designed and built in the 1950's, could cruise at mach 2+ while carrying a full external weapons load until it ran out of fuel.
There is a very real price to pay for stealth coatings and materials.

Keeping the enemy blind to your existence is more important than being able to run away fast. It's hard to outrun a missile.

Also in the F-22, there are 2 engines producing a little more than half the thrust each, so a smaller heat signature per engine.

And they have the special square thrust vectoring nozzles for all aspect stealth, with the afterburners embedded fairly deeply within. The nozzles are said to be one of the most expensive parts of the aircraft, being actively cooled to reduce the heat signature, as well as moving in 2 axis for vectoring.

Lastly the F-22 is designed for supercruise up Mach 1.5, so is less reliant on afterburner.

johns624 wrote:

kitplane01 wrote:

Climb high. Start the afterburner. Get to Mach 1.6. Start the clock. Turn off the afterburer and go into a dive. Stop the clock. Continue the dive maintaining speed. The clock does not run.

This would be done why?

Who knows. Chasing someone in a dogfight???

The point is that the stated limitation is one on afterburner time and speed, not just speed.

johns624 wrote:

Keeping the enemy blind to your existence is more important than being able to run away fast. It's hard to outrun a missile.

It is actually pretty easy to outrun a missile.

In a tail chase example with a fighter running away at Mach 2. A missile with a Mach 4 top speed might only average Mach 3 across its entire flight. So if the chasing fighter launches an AMRAAM missile at 50 miles away, the missile has to travel nearly 150 miles by the time it hits the target. The AMRAAM has successfully been outrun.

While in a head on engagement with both fighters flying towards each other at Mach 1 let's take an example where an AMRAAM missile is launched 150 miles or 3 times the distance away this time. The missile only has to fly around 100 miles and AMRAAM will probably hit the target.

In this head on engagement example if one of the fighters detects a missile launched at it while the missile is still 100 miles away then all it needs to do is turn around and the missile has instantly been outrun.

The No Escape Zone NEZ of a missile is actually extremely small. This is the zone where it can't be outrun.

Ground launched missiles can also be avoided in the same way. The SAM can be launched earlier if the fighter is flighting towards it. However if the fighter suddenly turns 90 degrees after the missile is launched then the missile might run out of energy.

With the USAF 6th gen I could it flying at 70,000ft and then being able to rapidly turn 90 degrees at 9G and be at Mach 2.5 within 30 seconds. Most SAM systems could be outrun. The turning and acceleration would make it more difficult to hit than an SR-71 in my opinion despite it flying 30,000ft lower.

RJMAZ wrote:

With the USAF 6th gen I could it flying at 70,000ft and then being able to rapidly turn 90 degrees at 9G and be at Mach 2.5 within 30 seconds. Most SAM systems could be outrun. The turning and acceleration would make it more difficult to hit than an SR-71 in my opinion despite it flying 30,000ft lower.

So you’re saying it can accelerate in a 9g turn at ~ Mach 2.0? At 70,000 feet? Cruising, I’m assuming? Some materials it’s made of. Unubtanium?

30,000 feet lower? Are you implying the SR-71 flew at 100,000 feet?

LyleLanley wrote:

So you’re saying it can accelerate in a 9g turn at ~ Mach 2.0? At 70,000 feet? Cruising, I’m assuming? Some materials it’s made of. Unubtanium?

I'm saying exactly what I'm saying. "being able to rapidly turn 90 degrees at 9G and be at Mach 2.5 within 30 seconds."

I would assume the starting speed would be Mach 1.8 which is the "supercruise" non-afterburner speed of the F-22. A 90 degree turn at 9G would take approximately 10 seconds. Afterburners would be engaged during the turn to minimise speed loss. An F-22 would only drop down to approximately Mach 1.5 doing such a turn. There is now 20 seconds remaining for the aircraft to accelerate to Mach 2.5.

This is not unubtanium. This is simply F-22 levels of speed, agility and acceleration but in an aircraft with approximately double the range. This range allows it to use supercruise for a large portion of the mission profile.

RJMAZ wrote:

johns624 wrote:

Keeping the enemy blind to your existence is more important than being able to run away fast. It's hard to outrun a missile.

It is actually pretty easy to outrun a missile.

In a tail chase example with a fighter running away at Mach 2. A missile with a Mach 4 top speed might only average Mach 3 across its entire flight. So if the chasing fighter launches an AMRAAM missile at 50 miles away, the missile has to travel nearly 150 miles by the time it hits the target. The AMRAAM has successfully been outrun.

While in a head on engagement with both fighters flying towards each other at Mach 1 let's take an example where an AMRAAM missile is launched 150 miles or 3 times the distance away this time. The missile only has to fly around 100 miles and AMRAAM will probably hit the target.

In this head on engagement example if one of the fighters detects a missile launched at it while the missile is still 100 miles away then all it needs to do is turn around and the missile has instantly been outrun.

The No Escape Zone NEZ of a missile is actually extremely small. This is the zone where it can't be outrun.

Ground launched missiles can also be avoided in the same way. The SAM can be launched earlier if the fighter is flighting towards it. However if the fighter suddenly turns 90 degrees after the missile is launched then the missile might run out of energy.

With the USAF 6th gen I could it flying at 70,000ft and then being able to rapidly turn 90 degrees at 9G and be at Mach 2.5 within 30 seconds. Most SAM systems could be outrun. The turning and acceleration would make it more difficult to hit than an SR-71 in my opinion despite it flying 30,000ft lower.

You ignored half my statement. Basically, it's better to not have to outrun a missile because your intact stealth keeps them from seeing you.

johns624 wrote:

744SPX wrote:

All the more amazing that the (essentially) all aluminum B-58, designed and built in the 1950's, could cruise at mach 2+ while carrying a full external weapons load until it ran out of fuel.
There is a very real price to pay for stealth coatings and materials.

Keeping the enemy blind to your existence is more important than being able to run away fast. It's hard to outrun a missile.

No aircraft is completely invisible to enemy radar. Period.

And while stealth doesn't have a whole lot of room for improvement, radars do.

744SPX wrote:

johns624 wrote:

744SPX wrote:

All the more amazing that the (essentially) all aluminum B-58, designed and built in the 1950's, could cruise at mach 2+ while carrying a full external weapons load until it ran out of fuel.
There is a very real price to pay for stealth coatings and materials.

Keeping the enemy blind to your existence is more important than being able to run away fast. It's hard to outrun a missile.

No aircraft is completely invisible to enemy radar. Period.

And while stealth doesn't have a whole lot of room for improvement, radars do.

Never said it was. Radar is getting better but we're talking about the present, not the future. If stealth didn't work, air forces wouldn't be paying billions for it. If speed was so important, fighters would be much faster than they are.

RJMAZ wrote:

LyleLanley wrote:

So you’re saying it can accelerate in a 9g turn at ~ Mach 2.0? At 70,000 feet? Cruising, I’m assuming? Some materials it’s made of. Unubtanium?

I'm saying exactly what I'm saying. "being able to rapidly turn 90 degrees at 9G and be at Mach 2.5 within 30 seconds."

I would assume the starting speed would be Mach 1.8 which is the "supercruise" non-afterburner speed of the F-22. A 90 degree turn at 9G would take approximately 10 seconds. Afterburners would be engaged during the turn to minimise speed loss. An F-22 would only drop down to approximately Mach 1.5 doing such a turn. There is now 20 seconds remaining for the aircraft to accelerate to Mach 2.5.

This is not unubtanium. This is simply F-22 levels of speed, agility and acceleration but in an aircraft with approximately double the range. This range allows it to use supercruise for a large portion of the mission profile.

It is unobtanium. The F-22 doesn't reach those altitudes and speeds at the drop of a hat, but with a very specific climb profile that has to be adhered to in order to reach it. It's not maintaining those speeds and altitudes at 9 g's, either. For your pressure suited (and G-suit equipped, I presume) pilot to pull 9 g's, at 70,000 feet, in a much heavier aircraft, and then accelerate almost a full mach number in 20 seconds is pure fantasy.

Unless your aircraft is made of unobtanium. Then it would surely be possible.

Accelerating a full mach number in 20 sec is not doable for any current aircraft, but for a pure turbojet (or variable cycle engine in zero bypass mode) at 50-70k ft in an aircraft that has a thrust to weight ratio of greater than unity at its maximum TO weight, I think it's doable.
On the F-22 I've never heard of a max speed quoted as being anything higher than mach 2.25. With its fixed intakes that has to be the limit, realistically. It might even be a bit lower. Plus, you have the composites and stealth coatings. I'd be really surprised if they could handle anything much beyond 2.0. I mean, if newer stealth coatings have trouble with even mach 1.6...

Supersonic speeds have three main drag hurdles.

1) Transonic speeds between Mach 0.9 and 1.2 there is a big spike in drag. So acceleration rate reduces significantly.

2) Mach wave from the nose starts hitting the wing tips or canards causing a massive increase in drag.

3) Fixed air inlets have to be tuned for a certain speed range. Once above that range the engine performance reduces.

No current fighter has a clear full Mach between these hurdles. The F-111 with wings fully swept back is probably the best example. It is one of the few aircraft where it has a full Mach of acceleration without encountering one of these drag hurdles. The Mach wave will not touch the wing roots or wing tips and it has variable intakes. An F-111 with the new 200kn adaptive engines being tested would most likely be able to accelerate a full Mach in under 20 seconds.

The 6th gen fighter renderings show designs with such a large sweep angle. The design is clearly optimised for higher supersonic speeds. Surface temperature of an aircraft is more to do with the design shape than the speed. Hot spots can form on the nose, canopy, chines, leading edge extensions, canards, wing tips and leading edge of the stabilisers. The USAF 6th gen fighter renderings show none of these potential hot spots so it will be able to fly faster without coating issues. I see every design feature of a Mach 3 design but it will definitely have an operational speed limit to keep the maintenance of the coatings to a reasonable level.

RJMAZ wrote:

An F-111 with the new 200kn adaptive engines being tested would most likely be able to accelerate a full Mach in under 20 seconds.

The 6th gen fighter renderings show designs with such a large sweep angle. The design is clearly optimised for higher supersonic speeds. Surface temperature of an aircraft is more to do with the design shape than the speed. Hot spots can form on the nose, canopy, chines, leading edge extensions, canards, wing tips and leading edge of the stabilisers. The USAF 6th gen fighter renderings show none of these potential hot spots so it will be able to fly faster without coating issues. I see every design feature of a Mach 3 design but it will definitely have an operational speed limit to keep the maintenance of the coatings to a reasonable level.

Ah, ok. In other words, you're just spitballing when you say that a reengineed F-111 would be a beast off the line. Or that your "analysis" of vaporware which so easily violates the laws of physics by not having hot spots on the parts of the aircraft that hit the airflow at 2000+ mph is also just spitballing. And that it can do 9 g's despite the thermal stress such an environment guarantees.

This seems of the same rigor as your KC-46 "analysis" that supposes Peggy's ZFW is a full 25,000 pounds less than what she does weigh.

Unobtanium, indeed.