Originally posted by matej
There is no need to have the best plane, but you must have the plane that is able to meet USAF requirements (no matter how stupid they are) as best as possible. And this is (my opinion about) why YF-23 lost.

I don't fallow! The USAF said that both ATF contenders met and Improved upon the requirements they had issued.

No offence, but What point are you trying to make?

Tim

Originally posted by matej
And about YF-22 vs. YF-23 - I think that the main point was what I already studied at university - and its marketing. There is no need to have the best plane, but you must have the plane that is able to meet USAF requirements (no matter how stupid they are) as best as possible. And this is (my opinion about) why YF-23 lost.

Actually, as long as both designs met the minimum stated requirements, it strictly becomes an issue of lowest bidder, regardless of how much one design may have outperformed the other. That's how US Government contracting works. "As much as you need, but no more than you have to"

Maybe the other example should make my point much clear. Imagine that you are ordinary man that issued requests:

"I want to move from town A to B by car. Please offer me the five seat car that is capable to reach the speed 100 km/h, with fuel consumption 6l/100km. Expences limit is 500 000 USD"

Two contenders responded. First offered the latest hydrogen powered Mercedes with innovative drive system that is capable to reach 250 km/h with fuel consumption 3l of hydrogen per 100 km. Cost is 495 000 USD.

Second contender offered some standard petrol powered Ford sedan that is capable to reach 130 km/h with fuel consumption 5,5l/100 km. Cost is 350 000 USD.

What do you think, which one will the most of the people choose? The first one with the greatest performances or the second that is closer to the requested specifications? Okay, when you will have the car (plane) that is more capable and ALSO cheaper, then there is not a problem with the decision. But when the both cars met all the specifications and this with greater performances is more expensive, you will ask yourself: "Do I really need (want) to pay more for performances that pass my requests?" And thats my point. You must always have in mind, who is paying the bill. So not always the best product is the winner, but the winner is always the product, that is closest to the customers requests, wishes, expectations and paying capabilities.

Personally I like F-23 much than F-22, but I can only repeat the official USAF attitude: "F-22 better answered our requirements" Thats it.

Originally posted by matej
There are hundreds of interesting papers, it depends on what you want to know. From all materials, papers, flight data, plans, etc. that I have about YF-23 and F-23A I found this the most relevant to the discussion.

Hundreds soley dedicated to the YF-22 and YF-23?



I've got loads of papers off them before, but not for that kinda stuff

Originally posted by matej
Maybe the other example should make my point much clear...pretty much everything I said in an earlier post...Personally I like F-23 much than F-22, but I can only repeat the official USAF attitude: "F-22 better answered our requirements" Thats it.

I agree... but let's take it to the next logical step since you have all of these papers on the YF-23. In your opinion, do you think that if the YF-23 had been chosen, that it's further development would have been as problematic (delays, cost overruns, design changes) as the YF-22/F-22's has been? Was the YF-23 closer to "production standard" at the time of the ATF Fly Off than the YF-22? or was the YF-22 closer to production standard? I don't really know - but I would think that that would have also played a large factor in the final ATF decision.

Originally posted by crusader97
I agree... but let's take it to the next logical step since you have all of these papers on the YF-23. In your opinion, do you think that if the YF-23 had been chosen, that it's further development would have been as problematic (delays, cost overruns, design changes) as the YF-22/F-22's has been? Was the YF-23 closer to "production standard" at the time of the ATF Fly Off than the YF-22? or was the YF-22 closer to production standard? I don't really know - but I would think that that would have also played a large factor in the final ATF decision.

Wooowwww wooowwww woooowwww!!!!


All of the problems going from YF-22 to F-22A have been political, they (politicans and generals) arse about and make late changes to the project, they push up costs - then have the cheek to complain about the cost rises. Sorry, but if the stupid aholes had enough brains to specify a project goal they don't change halfway through then the costs wouldn't rise.


The YF-23 would have experienced the exact same problems - maybe even worse since the missile bays may not have accepted JDAMs etc so easily with their mounting mechanisms. However a modified YF-23 may have been more suitable for adapting to the role defined for the intrim strike bomber (thus resulting in a larger purchase of F-23s).

All aircraft development programs have problems - but I think that the YF-22 may have had more than it's share. Sure, many of the PURCHASING delays were political, but having a prototype crash did not have a positive effect on the development timeline. Neither did USAF program reviews "that found that the F-22 engineering and manufacturing development program required additional funding and time to have a stable design before entering production." This was as late as the '97 budget - after 5 years of full scale development. There are other GAO reports stating that "In early 2000, the Air Force anticipated that six aircraft would be available for flight- testing
at the Flight Test Center by December 2000. However, only two flight-test aircraft actually
were available. Contractor and Air Force officials told us that the test aircraft took longer to
manufacture and assemble than planned because of design changes and modifications to the
aircraft, parts shortages, and the need to complete certain assembly tasks out of sequence." (March 2001 GAO report to Congressional Committee)
The YF-22 development process is littered with stuff like this.

Originally posted by crusader97
All aircraft development programs have problems - but I think that the YF-22 may have had more than it's share. Sure, many of the PURCHASING delays were political, but having a prototype crash did not have a positive effect on the development timeline. Neither did USAF program reviews "that found that the F-22 engineering and manufacturing development program required additional funding and time to have a stable design before entering production." This was as late as the '97 budget - after 5 years of full scale development. There are other GAO reports stating that "In early 2000, the Air Force anticipated that six aircraft would be available for flight- testing
at the Flight Test Center by December 2000. However, only two flight-test aircraft actually
were available. Contractor and Air Force officials told us that the test aircraft took longer to
manufacture and assemble than planned because of design changes and modifications to the
aircraft, parts shortages, and the need to complete certain assembly tasks out of sequence." (March 2001 GAO report to Congressional Committee)
The YF-22 development process is littered with stuff like this.

You see the bits in bold - how do you think they came about?

They are what pushed the program back alot [ok, the crash didn't help either!]

But consider it this way, the YF-22 flew, and flew well... it could carry and fire missiles, could supercruise, had a low radar signature, TVC etc etc etc... then the DOD/USAF decided they wanted the F-22 to do more A2G than they originally intended - cue design changes.

Originally posted by kilcoo316
They are what pushed the program back alot [ok, the crash didn't help either!]

But consider it this way, the YF-22 flew, and flew well... it could carry and fire missiles, could supercruise, had a low radar signature, TVC etc etc etc... then the DOD/USAF decided they wanted the F-22 to do more A2G than they originally intended - cue design changes.

Yes, it did fly well, and did everything the USAF expected and more. But I vaguely remember more than a few AvWeek articles about several changes to the wing design. I think these were mostly in the mid-'90s, before the big push to make the F-22 a flying Swiss Army knife. I wish I could recall more or had the time to look them up, but I think that the wing changes dealt mostly with increasingly the maneuverability for air-to-air (not a bad thing).

One of the great things about the YF-23 was that it seemed so pure - a lot like the SR-71. You could tell that it was meant to do one thing and do it extremely well.

Originally posted by matej
This is question for the God, not for me. But I think that its allways the matter of the money. If the enough money is available, than almost every technical problem can be solved and we should have production F-22 or F-23 sometime in 1996. But.... its allways the matter of the money.

Yes, money is very important, but don't forget the A-12 debacle in 1991. I'm not sure you could throw enough money at it to fix that thing!

That's a great image of the F-23A by the way.

Originally posted by matej For everybody that dont believe that YF-23 was so manueverable as YF-22 I reccomend to find the test results of SHARC model tested in NASA Langley with identical general shape as YF-23. They proved the ability to almost unlimited turn in Z axis when the doors of the weapon bay are closed.

Is the SHARC supposed to be a light derivative of the YF-23 design? I had heard mention in another thread (it may have even been on another site) that the SHARC design was a proposed candidate (along with a full scale X-36) for the still unrevealed YF-24. Did you happen to come across anything that might suggest "further development" of the SHARC design into actual flying hardware?

Originally posted by kilcoo316
While the basic shape is similar, its the details at the nose/underside which is giving the SHARC its high alpha performance. Do the same with the YF-22 nose and you'd get the same effects.

Okay, since I am expert on history, not on aerodynamics, I will believe you. But are you able to say, that YF-23 cant do really high 60+ AOA because it does not have thrust vectoring? I am not arguing that TVC is not usefull, yes, it is. But what I say is that it is not THE ONLY WAY, how to make the aircraft very agile. The most opinions are in position, that YF-23 without TVS is as manueuverable, as Airbus A380. And its something what I cant agree with.

I'm fairly naive about such things but I wonder if the technology base behind a YF-23 would be more suited for a medium bomber/electronic warfare platform, e.g. a highly stealthy replacement for the {E}F-111's & B1's, and even now the F-117's kind of missions, maybe a "E/B-3" type of thing? Lower deployment and operation cost than the B2, perhaps designed without the nuclear missions of B2.

Perhaps it got shuttled into a black program and development continues?

If you have a "more promising' and whizzy technology but one whose corporate and production performance is distinctly inferior it seems that a logical outcome is to go to production with the other one, which is certainly more than adequate in its mission of air superiority and some ground-attack.

Don't underestimate that aspect of decision making: choosing poorly and having contractors come up with big overruns is bad for your career and the program.

There are other potential aspects that people may not be addressing. What about survivability? Maintenance time & cost? Anti-missile defenses?

Originally posted by matej
Okay, since I am expert on history, not on aerodynamics, I will believe you. But are you able to say, that YF-23 cant do really high 60+ AOA because it does not have thrust vectoring? I am not arguing that TVC is not usefull, yes, it is. But what I say is that it is not THE ONLY WAY, how to make the aircraft very agile.

The most opinions are in position, that YF-23 without TVS is as manueuverable, as Airbus A380. And its something what I cant agree with.

What is manouverability? There are 2 components to it - response rate (accelerations) and sustained performance. So you've got (in the 3 axis):

roll, pitch and yaw, each of which has

Roll response rate (view it as the time taken to get to max roll rate) and the maximum roll rate.

Pitch response rate (time taken to get to max rate, or g rating), and the maximum sustained pitch rate.

and the same for yaw. Each of these 6 properties of the aircraft will change with conditions, airspeed, air density, aircraft configuration (weight) etc.

In all these transient manouvering areas, I would expect the YF-22 to beat the YF-23, its a smaller machine in length and span, thus with less polar moments of inertia, and less air resistance to movement [For comparison, the F-16 still destroys the F-22 in roll response/rates... because its a smaller aircraft]. Note that only the pitch rates will be affected by the YF-22s TVC capability - as you said, TVC is not the be-all and end-all.




As well as these 'classical' descriptions of manouverability, the sustained turn rates of aircraft are also extremely important. The sustained turn rate will come from the aerodynamic efficiency of the airframe (how much drag does it generate when producing x amount of lift).

I would expect the YF-23 outperforms the YF-22 in subsonic sustained turn performance, by dint of its larger wing area, greater use of lift generating fuselage and less wing sweep [more lift generated].

However, in supersonic flight, the aerodynamic centre of the whole aircraft will move, usually backward - this requires the elevators to be angled downwards to keep the aircraft from pitching nose down (trimming). Using the elevators to perform this trim function will remove alot of their nose up pitching authority (as, its already used some of its movement to perform trimming functions). I've been told the YF-23's wing maintained its aero-centre from subsonic to supersonic flow. However the fuselage will not, and manouverability will be compromised to some degree (increased trim drag before beginning the manouvering).

The YF-22 used its TVC to trim the aircraft instead of the elevators, so full elevator movement was retained - this is what gives the F-22 its supreme supersonic manouvering capabilities. Depending on how much the fuselage interferes with aerodynamic centre movement (on the YF-23) will determine how close the YF-22 and YF-23 are in supersonic sustained turn performance. Again, you don't need TVC to do a decent job here with very careful aerodynamic design, but it helps.




As for high AoA manouvering, no aircraft without thrust vectoring can maintain full controllablity beyond its elevators stalling. The Flankers can do the cobra through use of momentum in pitching the nose up over 90 deg, and then using the large rearward shift in aerodynamic centre (all the wing and elevator is at the back - when at AoA 90 this is generating loads of drag) to pitch nose down again. The pilot is not in control of the aircraft - I define control as his/her ability to influence the aircraft at that moment in time though his/her inputs.

The YF-23 will not have that great a high AoA performance, its wing is not far back enough, and its elevators don't exist, so it will not be able to safely achieve the 90+ deg AoA of the Flanker or Raptor [it doesn't have anything that will force the nose back down]. It will certainly not have carefree handling like the YF-22. I don't even think the YF-23 would outperform the F-18 in high AoA performance to be honest.

Here, TVC comes into its own - when the wings and elevators are stalled, you've no aileron or elevator control authority, you might have some rudders with good placement of the vertical stabilisers. However, you still can pitch (and roll and yaw with the Su-30MKI/Su-35 or OVT configs) wih TVC, giving you back control (as I define it).




So how manouverable is the YF-23?

Is it like a Jumbo, or a Raptor?

I would reckon its response rates are slightly better than an F-15 (which is far short of the YF-22), its sustained turn performance subsonically is better than the YF-22, supersonically, I don't know.

Its high AoA performance I think would be some way short of the YF-22, and behind the F-18 as well. It also will definitely not have carefree handling - which may or may not be something the USAF attaches alot of importance to. With the emphasis on situational awareness, worrying about max AoA limits may be considered critical.

MateJ,

Thank you for the blow up's of the two designs! It really helped me to put them side by side. After a period of careful study, I now see what you were trying to show me. I honestly couldn't see it before. The Aircrafts have quite a few Differences, don't they? I'm assuming that the F-23 would have probably had different handeling qualities then the YF-23.

Side Note: I never intended to come across as ignorant. I wear glasses and sometimes I have a very hard time seeing details!

I may have strong beliefes, but I will admit when I know I am wrong! Boy, I sure made a huge fool of myself this time!

Tim

How do we know what the F-23 production craft looks like if it never went into production and how could we safely assume what it would look like and what exactly is Matej basing his illustrations on?

Shattered OUT...