Sukhoi T-50 PAK FA manouverability versus F-22

[LowObservable]

F-14D - Exactly. Some funny stuff out there, like seeing a test routine run on a nuclear weapons component in 2002, using a Commodore 64.

 

[sferrin]

- Use of advanced parts of the flight envelop to maximise stealth in a known direction

Most modern stealth aircraft do this. For example, on the B-2, the defensive systems are integrated with the flight controls. When a threat is detected the flight control laws change to alter the RCS for that threat. Control surface deflections are different, some components aren't allowed to flex as much, etc.

Very interesting - I'd read about the idea but I hadn't heard that it had been implemented - and in a flying wing no less. The B-2 really is a technological marvel (even if it has a 286 processor).

As long as it does the job it wouldn't matter if it had an 8088.

...until you had to try and fix it. This is a significant concern of USAF on both the B-2 and the F-22.

True. At the same time how much would it cost to update it all considering you probably don't want to go the COTS route?

 

[latenlazy]

- Use of advanced parts of the flight envelop to maximise stealth in a known direction

Most modern stealth aircraft do this. For example, on the B-2, the defensive systems are integrated with the flight controls. When a threat is detected the flight control laws change to alter the RCS for that threat. Control surface deflections are different, some components aren't allowed to flex as much, etc.

Very interesting - I'd read about the idea but I hadn't heard that it had been implemented - and in a flying wing no less. The B-2 really is a technological marvel (even if it has a 286 processor).

As long as it does the job it wouldn't matter if it had an 8088.

...until you had to try and fix it. This is a significant concern of USAF on both the B-2 and the F-22.

True. At the same time how much would it cost to update it all considering you probably don't want to go the COTS route?

I once heard the biggest cost wasn't hardware but software. Changing a processor could mean having to rewrite the entire operating system suite, apparently.

 

[Dragon029]

Very much so; your processor only works in machine code, inserting, copying, deleting registry values, etc. It's from on top of this very simply language (consisting of ~50 commands) that more advanced languages are built, all the way up to your advanced languages that programmers write their code in. If you change your higher-level language, you only need to hire programmers with different experience, or give them a conversion course. If you change processor, you either need to retrieve code / manuals that may not exist, and/or you need to rework the way you program:

A simplified analogy:
Your processor receives a command like "2^4=?".
With a modern processor, it may interpret this simply as repeated multiplication "2x2x2x2=?".
With an older processor, it might be limited to only addition, so therefore it has to interpret this as "2+2+2+2+2+2+2+2=?".

Suppose you gave your processor the statement "2xA=?"
Working with multiplication only, you can still say "2xA=?"
But if you're restricted to addition / subtraction, how can you represent that statement without knowing A? And so now, any part of your code that uses this form of language must be removed and replaced with an alternative method.

 

[F-14D]

- Use of advanced parts of the flight envelop to maximise stealth in a known direction

Most modern stealth aircraft do this. For example, on the B-2, the defensive systems are integrated with the flight controls. When a threat is detected the flight control laws change to alter the RCS for that threat. Control surface deflections are different, some components aren't allowed to flex as much, etc.

Very interesting - I'd read about the idea but I hadn't heard that it had been implemented - and in a flying wing no less. The B-2 really is a technological marvel (even if it has a 286 processor).

As long as it does the job it wouldn't matter if it had an 8088.

...until you had to try and fix it. This is a significant concern of USAF on both the B-2 and the F-22.

True. At the same time how much would it cost to update it all considering you probably don't want to go the COTS route?

Actually, they did do that on the F-35. USAF and DoD were shocked on the F-22 when it was realized that the US gov't was no longer a driver in chip design and computer tech and that the DoD, while a BIG customer, was not that large in proportion to the GARGANTUAN market out there.

One of the reasons the F-22 is so expensive to maintain is that it is full of chips that the original companies don't have much interest in supporting, so they have to deal with (more expensive) custom houses. In fact, during EMD USAF was told by some contractors that they weren't interested in participating in the production program because the F-22 market was so small it wasn't worth the effort. And this was when USAF still thought it was getting 700 of the birds!

Whatever else you might say for or against the F-35, the lesson was learned and it has a much more open architecture and the ability to integrate different processors will be much smoother.

 

[sferrin]

Do COTS chips/boards/etc. measure up in the hardness department? It would suck if EMP grounded all our fancy new COTS-equipped aircraft.

 

[F-14D]

Do COTS chips/boards/etc. measure up in the hardness department? It would suck if EMP grounded all our fancy new COTS-equipped aircraft.

I suspect the aircraft is designed to protect against that, or like most previous a/c except bombers, they're accepting the risk. Reality remains that the DoD market is too small and too slow in doing things to be able to drive the design of mass produced stuff in this field.

 

[Deleted member 4570]

Do COTS chips/boards/etc. measure up in the hardness department? It would suck if EMP grounded all our fancy new COTS-equipped aircraft.

I suspect the aircraft is designed to protect against that, or like most previous a/c except bombers, they're accepting the risk. Reality remains that the DoD market is too small and too slow in doing things to be able to drive the design of mass produced stuff in this field.

Most Logic design can be targetted for different Packages. The 'silicon' by itself is very fragile. Its the Packaging that makes it robust for the temperature/EM Interference etc.
Choice of semiconductor also helps. Most Chip design companies can do the design and hand over the fabbing to the few companies still doing it now. But starting a new process just for a few wafers is not any company would do, consumer electronics is much more lucrative.

 

[latenlazy]

Very much so; your processor only works in machine code, inserting, copying, deleting registry values, etc. It's from on top of this very simply language (consisting of ~50 commands) that more advanced languages are built, all the way up to your advanced languages that programmers write their code in. If you change your higher-level language, you only need to hire programmers with different experience, or give them a conversion course. If you change processor, you either need to retrieve code / manuals that may not exist, and/or you need to rework the way you program:

A simplified analogy:
Your processor receives a command like "2^4=?".
With a modern processor, it may interpret this simply as repeated multiplication "2x2x2x2=?".
With an older processor, it might be limited to only addition, so therefore it has to interpret this as "2+2+2+2+2+2+2+2=?".

Suppose you gave your processor the statement "2xA=?"
Working with multiplication only, you can still say "2xA=?"
But if you're restricted to addition / subtraction, how can you represent that statement without knowing A? And so now, any part of your code that uses this form of language must be removed and replaced with an alternative method.

Well, I knew that much What I did learn in that conversation was the language layer they wrote the F-22's OS in. I guess going with closed source made sense at the time the designs were conceived, but for my generation it sounds remarkably...shortsighted.

 

[F-14D]

Well, I knew that much What I did learn in that conversation was the language layer they wrote the F-22's OS in. I guess going with closed source made sense at the time the designs were conceived, but for my generation it sounds remarkably...shortsighted.

You've got to go back in time to those days.

There had never been a plane so computerized as the F-22 and given what they had experienced in the past they thought they could still drive the market. They didn't realize how small a part of the market they were becoming, and that was their big mistake.

Things were different years ago. Why, it was so primitive then that they could make change in their head, enter a fast food order by the name of the item and price and even tell time on a non-digital clock, even if there were no numbers on the face!

 

[latenlazy]

Well, I knew that much What I did learn in that conversation was the language layer they wrote the F-22's OS in. I guess going with closed source made sense at the time the designs were conceived, but for my generation it sounds remarkably...shortsighted.

You've got to go back in time to those days.

There had never been a plane so computerized as the F-22 and given what they had experienced in the past they thought they could still drive the market. They didn't realize how small a part of the market they were becoming, and that was their big mistake.

Things were different years ago. Why, it was so primitive then that they could make change in their head, enter a fast food order by the name of the item and price and even tell time on a non-digital clock, even if there were no numbers on the face!

What amazed me from your earlier post was that they still hadn't seemed to realized this in the late 90s early 2000s

 

[F-14D]

What amazed me from your earlier post was that they still hadn't seemed to realized this in the late 90s early 2000s

They had, but that was 10 years too late for the F-22.

 

[EricChase88]

I do not understand why F-22 would have more max speed than T-50. F-22 materials are older and use polycarbonate canopy. T-50 use silica glass canopy which have better heat resistance. It is also framed so its even stronger than F-22 canopy.

 

[sferrin]

I do not understand why F-22 would have more max speed than T-50. F-22 materials are older and use polycarbonate canopy. T-50 use silica glass canopy which have better heat resistance. It is also framed so its even stronger than F-22 canopy.

You're assuming that the canopy is the limiting factor. Not necessarily the case.

 

[Radical]

I do not understand why F-22 would have more max speed than T-50. F-22 materials are older and use polycarbonate canopy. T-50 use silica glass canopy which have better heat resistance. It is also framed so its even stronger than F-22 canopy.

You're assuming that the canopy is the limiting factor. Not necessarily the case.

Wasn't the F-16 limited to 800 knots at lower altitudes due to the canopy? Also, I think F-15 is structurally redlined at Mach 2.8, though I'm not sure if that's because of the canopy or not.

 

[sferrin]

I do not understand why F-22 would have more max speed than T-50. F-22 materials are older and use polycarbonate canopy. T-50 use silica glass canopy which have better heat resistance. It is also framed so its even stronger than F-22 canopy.

You're assuming that the canopy is the limiting factor. Not necessarily the case.

Wasn't the F-16 limited to 800 knots at lower altitudes due to the canopy? Also, I think F-15 is structurally redlined at Mach 2.8, though I'm not sure if that's because of the canopy or not.

I'd read it was dropped from 2.7 to 2.5 because of the canopy. Still, if your airframe materials limit you to 2.2 the canopy isn't going to be the limiting factory.