The Truth about the Raptor

Anything goes, as long as it is about the Lockheed Martin F-22 Raptor
  • Author
  • Message
Offline

Fighter_Mafia

Newbie

Newbie

  • Posts: 4
  • Joined: 18 Oct 2006, 20:40

Unread post18 Oct 2006, 22:43

There has been a lot of talk about the Raptor, especially in the recent months because of the criticism of the aircraft by Sprey and Stevenson, and previously by Riccioni. Hundreds of messages are sent, but there seems to be no progress in the debate: 80% of messages are from Raptor advocates who say that we need the F-22 because it can destroy any threat out there while the legacy fighters cannot (frankly, Raptor advocacy is overwhelming in this forum -some of them even claim that the Raptor is some kind of aerial nuke or that it´s cheaper than F-15), F-22 critics argue that it cannot beat the latest Su-thirtysomething which has thrust vectoring in all directions and all that. But actual, empirical data and facts about various aircraft cost and performance are seldom seen, and the debate never really gets deep about these issues. This, despite the data being available, even provided by a Raptor advocate. It wasn´t in the Riccioni report or CIA or some classified ultra-secret Air Force report - it was in the internet for free. I´ve always been interested on the Raptor and read the debates on it, though not participating; but in the recent months i´ve compiled quite a bit of data on the Raptor. This data surely will surprisemean understand official reports, flight manuals, etc. - not unsubstantiated pilot, service or contractor claims without supporting data.

We´ll start with performance - that is, maneuverability, energy-maneuverability, fast-transients, and climb/acceleration. Even though USAF has quietly sweeped this issue under the carpet in the past years, it was originally part of the requirement, one the four pillars which were to provide the ATF with unprecedented and unrivalled combat effectiveness.

http://home.att.net/~jbaugher4/f23_1.html

The requirement now called for a fighter with a Mach 1.5 cruising speed, a takeoff roll of only 2000 feet, a gross takeoff weight of no greater than 50,000 pounds and a combat radius of more than 700 nautical miles. The aircraft was to be capable of performing 5g turns at Mach 1 and 6g turns at Mach 1.5 at 30,000 feet. At 10,000 feet, the ATF was to be capable of pulling instantaneous turning acceleration loads as high as 9 gs at Mach 0.9 and was to be capable of performing sustained 2g turns at Mach 1.5 at 50,000 feet. At sea level, the ATF was to be capable of accelerating from Mach 0.6 to Mach 1.0 in 20 seconds. At 20,000 feet or 30,000 feet, the aircraft was to be capable of accelerating from Mach 0.8 to Mach 1.8 in 50 seconds. The unit flyaway cost was to be no more than $40 million in 1985 dollars (later reduced to only $35 million), and the life-cycle cost was to be no more than that of the F-15.


Furthermore, Raptor advocates in this forum and elsewhere constantly claim (and even more so after seeing a few Cobras at helicopter speeds in F-22 airshow videos) that its performance is one of the reasons for which it has an advantage over the F-35, the ´´low´´ end of the ´´high-low´´ mix (they instanly claim that it is the same policy that created the Eagle and Viper, revealing their ignorance about Air Force history). They say, JSF cannot go toe-to-toe with a Flanker, Eagles were smashed in dogfights by Flankers in India, and so and so.

Impressive requirements, way better than legacy fighters. Here is the performance of the F-16 block 15, it cannot sustain those turns even at 5.000 ft lower (thanks to Raptor_One for posting the graph):

Image


It is interesting to see the ´´evolution´´ of the Raptor requirements over time - backwards evolution, of course:

http://www.f22-raptor.com/technology/data.html

(for more insights on those requirements, check this link by Gao)

http://www.gao.gov/archive/1999/ns99055.pdf

The Air Force quite strangely quotes here the performance requirements and numbers for the operational F-22 - which have fallen precipitously. From 5g turns at mach 1 it has fallen to 3.7g at mach 0.9, surely below 3.5 at mach 1. You say, ok, but it still is a great performer despite the loss and despite not reaching its goal. ¡WRONG! Do some math: the Viper blk 15 (which is no even the best energy-maneuverability version, earlier blocks are better a 30/50s are way better too) sustains almost 11 G at mach 0.9 5.000 ft; it losses about 2.5 Gs with the next 10k ft to 7.4, then it losses some 2.3 Gs till 5.1 at 25k feet. That is, the loss of STR becomes smaller with altitude (in fact, a ´´sustained turn rate´´ of 1G is level flight and it is not reached until 60k!). It becomes obvious - at 30k, the Viper can sustain more than 3.7 Gs, probably more than 4. Perhaps Raptor_One can provide more information on the subjetc. And remember, this is a rather mediocre version...of a 30-year-old tiny, inexpensive lightweight fighter!And it´s competing against history´s most-expensive ´´super-fighter´´! Where are all those that claimed the Viper to be the ´´low´´ end of the Eagle-Viper mix?(I know it wasn´t, but this was a frequent claim exacerbated by the Air Force, who didn´t want the little fighter beat their super-duper-Eagle) Then how much superior would be the Eagle to the Raptor? But wait, it gets way worse.

--------------------------------------------------------------------------------------------------------------------------------

Edit to say that I´ve found new data, which is definitive.

http://www.d-n-i.net/boyd/pdf/fast_transients.pdf

This is definitive. This really shows what a mediocre performer the Raptor is and how far below its goal it has fallen. The Viper didn´t beat the Raptor at that point of the envelope ´´because it was designed to excel at that point and elsewhere it losses´´, or ´´because the Raptor has a much bigger mission in payload/range´´. It just beat it because the Raptor is not so hard to beat. The F-4E, loaded with 4 Sparrows, at mach 0.9/30k, sustains almost 6 º/s, which is about 3 G. To make it clear (for mach 0.9/30k, sustained turn):

F-4E F-16 F-22 ATF goal

3 g 4 g 3.7 g About 5.5 g
5.75 º/s 7.8 º/s 7 º/s 11 º/s


Even though the Raptor has a much higher t/w than the Phantom and clearly higher than Viper, it has quite lower aspect ratio than the the former and much lower than the latter. This means that when induced drag is greater, the Raptor suffers more. Hence, at lower speeds the Raptor will compare worse to the other fighters (and better at higher speeds).

---------------------------------------------------------------------------------------------------------------


The hype and myth that have hidden the true capabilities of this aircraft reach outrageous levels. This is not a good example of over-hype compared to the absurd claims we´ve been hearing, but it´s one of the most obvious and easy to unmask:

http://www.codeonemagazine.com/archives/1991/articles/jul_91/jula_91.html

One of those so respected test pilot makes this statement:

As a comparison, the YF-22 roll rate is equal to, if not slightly faster than, the F-16 roll rate, within the F-16 angle of attack envelope.


He seems to be candid, in fact he credits the old inexpensive fighter with almost comparable agility to that of the new super-duper-fighter (well, at least´´within its envelope limits´´). Now looks at the real aerodynamical studies data (see page 15):

http://www.aoe.vt.edu/~mason/Mason_f/F22.ppt

Well, the Raptor is about twice or thrice as good as the Eagle...but one moment! It is well below the roll rates of the ´´low cost, low capability´´ end of the high-low mix. This is physics, bigger aircraft tend to have less roll rate and hence be less agile. Even with sophisticated and expensive control surfaces, the F-22 again cannot match the Viper performance. BTW the Viper is about 3-4 times better than the Eagle (nothing new but still remarkable). You can also see how much ´´useful´´ for maneuverability and agility (in combat) are those 60º AoA so fashionable in airshows. Note that this is for the technology demonstrator YF-22, which is lighter than the production operational fighter F-22 - some 4 tons lighter. So Viper´s advantage most probably is greater.


Check again the ATF requirements and match them with the F-22 requirements - well, they´re kind of unmatchable - I don´t know if this word exists. F-22 requirements (any of those which provide real data) aren´t impressive at all. The best is acceleration which is quite good but worse than the 30-year-old YF-16: 56 seconds at 35k ft from 0.9 to 1.6 (the Raptor data is 53 from 0.8 to 1.5 at 30k ft). To be fair with the Raptor, at least the data is clearly better than production F-16A (70 sec from 0.9 to 1.6 a 35k). James P. Stevenson´s ppt on the F-22 quoted numbers at the transonic region acceleration for blk 50 better than those of the Raptor, at all heights, though not by much - the Eagle fell behind.

The same goes for range, either Eagle C or Tomcat or Viper can match that (I assume it´s on internal fuel). I don´t have the exact data right now but be sure of it. Range was not a great issue for this fighter, however (nor should it be for most fighters), 1.700+ miles is enough.

As for supercruise, 100 nm is way better than legacy fighters (except perhaps the F-104, especially the Dash 19). But it is nowhere near really useful supercruise missions. Nor does it come close to the goal of 600-700 nautical miles radius of action, or 100 subsonic + 400 supersonic for operations deep in enemy airspace. Raptor advocates claiming that it can fly ´´constantly´´ at mach 1.5 just because it can get there without afterburner should think it two times. Supersonic endurance is rather limited.


Anyway, be it either a match, a 5% advantage for Raptor or a 5% disadvantage, the gross question remains, if it is a brand-new design against a 27-year-old fighter, wouldn´t it have to be much better?And if it is by far history´s most expensive supposed duper-fighter against an inexpensive fighter, wouldn´t it have to be A WHOLE BUNCH BETTER?

Notice that all this data comes from the Raptor team website, official flight manuals for the Fighter Weapons School, and various aerodynamic studies from AIAA, they aren´t empty claims. In fact, the Raptor team website data are probably hyped to make the F-22 appear better - just look at the ridiculous maintenance claims. Interestingly, maintenance/sortie rate was the only issue noted by Gao in their official reports.



I´ve posted enough for now, but I will continue. Next will come, why and howdoes the Raptor perform so badly, why it does not even come close to its requirements despite having sky-rocketed its cost, and also some other issues and Raptor troubles. I would want to have debate. My point for the moment is clear - I agree on most points with the Riccioni report on the Raptor.



A final comment that makes evident the huge F-22 bias that a lot of members of this forum have. Super Hornet has been thoroughly criticised for being a ´´do-it-all´´ which ´´does not excel at anything´´, it is not as fast and powerful and maneuverable as previous fighters(including those of the Navy), and it cannot carry the bombload of previous attack airplanes (especially those carrier-borne) - interestingly, they never criticise its cost and instead focus on the useless mach 2+ speed of the Tomcat, no matter. I don´t consider the Super Hornet a good warplane at all, but the comparison serves. Those very same forum members who criticise the SH, don´t say a thing about the Raptor vs Nighthawk issue (excepto to remark that the Raptor is better at that task too, of course).

Well, the F-22 with is maximum stealth bomload of 2 x 1000 pounds, has a fuel fraction of 0.3. The F-117, an airplane sometimes criticised for its light bombload and short range (especially versus the B-2), has a fuel fraction of 0.35 while carrying 2 x 2000. Guess which has greater payload/range, and which is ´´a new airplane inferior to those of the past´´ as has been said of the SH.

Nor does the Raptor have the agility, situational awareness, energy and visual stealth of 30-year-old fighters for close-in dogfights. Of course Raptor advocates now will argue that the F-22 will shoot down anything at BVR. But think of it.
Last edited by Fighter_Mafia on 06 Nov 2006, 15:41, edited 3 times in total.
Resolution to most of these problems is For All to tell The Truth despite what it may lead to - E. E. Riccioni
Offline

checksixx

Elite 1K

Elite 1K

  • Posts: 1525
  • Joined: 20 Jul 2005, 04:28
  • Location: Langley AFB, VA

Unread post19 Oct 2006, 01:02

How's that Top Gun line go?..."Cough, Troll!"
Offline

Raptor_claw

Senior member

Senior member

  • Posts: 322
  • Joined: 29 Sep 2006, 07:11

Unread post19 Oct 2006, 01:22

checksixx wrote:How's that Top Gun line go?..."Cough, Troll!"


Absolutely, but hey, I ain't proud (or tired). I'll bite.....

Fighter_Mafia wrote:
The requirement now called for a fighter with a Mach 1.5 cruising speed, a takeoff roll of only 2000 feet, a gross takeoff weight of no greater than 50,000 pounds and a combat radius of more than 700 nautical miles. The aircraft was to be capable of performing 5g turns at Mach 1 and 6g turns at Mach 1.5 at 30,000 feet. ...

...
It is interesting to see the ´´evolution´´ of the Raptor requirements over time - backwards evolution, of course:

The Air Force quite strangely quotes here the performance requirements and numbers for the operational F-22 - which have fallen precipitously. From 5g turns at mach 1 it has fallen to 3.7g at mach 0.9, surely below 3.5 at mach 1.

This is an invalid extrapolation. The only data point you have to work with is the "3.7g at Mach 0.9" number. You have no idea what the number is at Mach 1.0 - it could very well still be 5g. Why do you think the requirement was higher at Mach 1.5? These engines are designed to shine supersonic. Also, Mach 0.9 to 1.0 is a gain of about 45 knots (calibrated) - means more qbar, less AOA required for same 'g', less drag, etc...

Fighter_Mafia wrote:You say, ok, but it still is a great performer despite the loss and despite not reaching its goal. ¡WRONG! Do some math: the Viper blk 15 (which is no even the best energy-maneuverability version, earlier blocks are better a 30/50s are way better too) sustains almost 11 G at mach 0.9 5.000 ft; it losses about 2.5 Gs with the next 10k ft to 7.4, then it losses some 2.3 Gs till 5.1 at 25k feet.
And where are you getting this data? I'm assuming that you got dog-house plots that you didn't include - that's fine, you don't need to. As an aside, the F-16 does not fly at 11G, so there is no way that data could be verified.

Fighter_Mafia wrote:It becomes obvious - at 30k, the Viper can sustain more than 3.7 Gs, probably more than 4.
Well, yeah, that's about what I could glean from the em plot you gave. What's your point? That it can sustain slightly more g's at one particular point in the sky. Okay.

Fighter_Mafia wrote:And remember, this is a rather mediocre version...of a 30-year-old tiny, inexpensive lightweight fighter!And it´s competing against history´s most-expensive ´´super-fighter´´!
Mediocre? Mediocre? Did you just use the word mediocre in a description of the F-16? wow. Don't think I've ever seen that before. But seriously, age, weight, and cost has nothing to do with it. The fact is the F-16 was designed specifically to excel in this very realm. The very fact that it is (was) light weight ('tiny' I guess you would say) gives it an inherent advantage in sustained load factor - that's what it was designed for. This data is with not even a fraction of the load of an F-22, etc, etc, etc. I considered your argument to be a complement to the F-16, not a legitimate insult to the F-22.

Fighter_Mafia wrote:The hype and myth that have hidden the true capabilities of this aircraft reach outrageous levels. This is not a good example of over-hype compared to the absurd claims we´ve been hearing, but it´s one of the most obvious and easy to unmask:

http://www.codeonemagazine.com/archives/1991/articles/jul_91/jula_91.html
One of those so respected test pilot makes this statement:
As a comparison, the YF-22 roll rate is equal to, if not slightly faster than, the F-16 roll rate, within the F-16 angle of attack envelope.


He seems to be candid, in fact he credits the old inexpensive fighter with almost comparable agility to that of the new super-duper-fighter (well, at least´´within its envelope limits´´).


Hate to repeat my earlier theme, but the fact is that the F-16 (clean) roll rate capability (at 1g) is obscene. There's just no other word for it.
Your big mistake is equating roll rate to agility. Obviously, roll rate capability needs to reach some level, but the F-16 (imo) goes way beyond that. What good, exactly, does a really quick 360 do if some guy is on your tail? NONE!
All the data you have is 1-g roll rate. Where roll rate does gain some importance is at elevated G's for reversing turns, etc. You have no data to make any meaningful comparisons or conclusions where it really matters. If you did, you would have to tell a different story.....

Fighter_Mafia wrote:Now looks at the real aerodynamical studies data (see page 15):
http://www.aoe.vt.edu/~mason/Mason_f/F22.ppt
Well, the Raptor is about twice or thrice as good as the Eagle...but one moment! It is well below the roll rates of the ´´low cost, low capability´´ end of the high-low mix.
This is physics, bigger aircraft tend to have less roll rate and hence be less agile. Even with sophisticated and expensive control surfaces, the F-22 again cannot match the Viper performance.
Again, all 1-g data - essentially meaningless. And, for clarification, your 'aerodynamical studies' data is actual flight data.

Fighter_Mafia wrote:You can also see how much ´´useful´´ for maneuverability and agility (in combat) are those 60º AoA so fashionable in airshows. Note that this is for the technology demonstrator YF-22, which is lighter than the production operational fighter F-22 - some 4 tons lighter. So Viper´s advantage most probably is greater.
I assume that since you put quotes around 'useful' that you were being sarcastic about the 60 AOA capability. Apparently 'we' are not all familiar with flight dynamics at very high AOA. 'Rolls' are no longer rolls, they become combination roll and yaw motions. Look at it this way, if you are rolling at 30 deg/sec for 1.0 seconds (at low AOA), you change almost exactly 30 degrees of bank angle, with almost no yaw rate, or change in heading. If you want to change that same 30 degrees of bank in 1.0 seconds at 60 AOA, you still need to generate 30 deg/sec of roll rate, but in order to remain coordinated (low sideslip) you have to generate a ton of yaw rate to go along with that. So, as you change 30 degrees of bank, you may change heading 50 or 60 degrees. So to look at a simple roll rate plot and say "it's not useful at high AOA" is just, well, uninformed. If you saw the same plot with yaw rate capability, you would see the different (i.e. the real) story. And, by the way, good luck extrapolating YF data to F. YF was a demonstrator only, not a fully flushed out and optimized design, especially at high AOA.

Fighter_Mafia wrote:Anyway, be it either a match, a 5% advantage for Raptor or a 5% disadvantage, the gross question remains, if it is a brand-new design against a 27-year-old fighter, wouldn´t it have to be much better?And if it is by far history´s most expensive supposed duper-fighter against an inexpensive fighter, wouldn´t it have to be A WHOLE BUNCH BETTER?
That's just it - it is a WHOLE BUNCH BETTER when you look at the system as a whole, and not a couple isolated performance points.

Fighter_Mafia wrote:Nor does the Raptor have the agility, situational awareness, energy and visual stealth of 30-year-old fighters for close-in dogfights.
Oh, but it does.
Offline

SpeakTheTruth

Active Member

Active Member

  • Posts: 145
  • Joined: 26 Jul 2006, 09:11

Unread post19 Oct 2006, 01:39

checksixx wrote:How's that Top Gun line go?..."Cough, Troll!"


Ok another troll accuser because of a negative view of the F-22.
Offline

TC

F-16.net Moderator

F-16.net Moderator

  • Posts: 3998
  • Joined: 14 Jan 2004, 07:06

Unread post19 Oct 2006, 02:13

Nah, Iceman's line in Top Gun was *COUGH*BULL$H!T!* :lol:

Here's the deal: Most of these so-called "experts", who know "the truth" have never even been around the d@mn plane, nor will they ever be.
Offline

idesof

Forum Veteran

Forum Veteran

  • Posts: 634
  • Joined: 29 May 2006, 22:59

Unread post19 Oct 2006, 02:32

I beg everyone to please resist the urge. Nothing good will come of engaging this troll. His mind shall not be changed nor shall he change anyone's mind. Just...let...this...die...
Offline

Scorpion1alpha

F-16.net Moderator

F-16.net Moderator

  • Posts: 1694
  • Joined: 21 Oct 2005, 00:47

Unread post19 Oct 2006, 04:07

Most of these so-called "experts", who know "the truth" have never even been around the d@mn plane, nor will they ever be.


Or those that claim to "speak the truth". :roll:

I don't like feeding trolls with stupid statements.
I'm watching...
Offline
User avatar

PhillyGuy

Forum Veteran

Forum Veteran

  • Posts: 637
  • Joined: 29 Sep 2006, 03:07

Unread post19 Oct 2006, 05:58

No thanks, I'll take the word of F-22 pilots over self proclaimed "experts" any day of the week. I am more than satisfied with what they have said (and demonstrated) about the maneuverability of the Raptor, that is what counts. NOT pointless theoretical speculation based on half truths and pseudo facts. Please resist the urge.
"Man will never be free until the last king is strangled with the entrails of the last priest."
Offline

allenperos

Forum Veteran

Forum Veteran

  • Posts: 631
  • Joined: 24 Feb 2005, 13:33

Unread post19 Oct 2006, 11:51

This is an interesting post. Thanks for the tech data on the F-16 performance. We're really getting political here as I'm sure this part of the net is probably anything but unconscientious towards this airplane. Many of you don't understand political ramifications of a new piece of hardware or maybe you do but are keeping quiet, that's good. Keep in mind the GOV keeps an algorithmic account of what's happening in the future far beyond our wildest imaginations.... :shock:

An algorithmic account means a prediction for the future guys. :?

I understand the jet has had problems getting to EOR due to mech probs, not software, it's been bad guys.... :cry:
F-16B, CC 80-0623 ERAU ROTC
MD-11, 90, 80, Cognizant Aerospace Technical Writer - Powerplant RR, GE, and P&W
Offline

SpeakTheTruth

Active Member

Active Member

  • Posts: 145
  • Joined: 26 Jul 2006, 09:11

Unread post19 Oct 2006, 12:56

I beg everyone to please resist the urge. Nothing good will come of engaging this troll. His mind shall not be changed nor shall he change anyone's mind. Just...let...this...die...


No this guy is no troll, just because he has been negative towards the F-22 the Raptor fans have gone on the defence by accusing him of being a troll. He has put a lot of time and effort into that thread so its beyond a troll attempt.

What TC said is true, most people who comment on these forums with facts/assumptions of the Raptor whether they are in favour or against it are inexperienced. Unless you are an experienced aerospace engineer you cannot compute those facts to make a conclusion about the Raptors performance. Bigger numbers don't always mean better. The only people who can comment on how the Raptor performs are the engineers who have had a significant role in the program or a Pilot who has had many hours flying it along with many hours in other modern fighter jets.

Thats what annoys me about comments of the Typhoon, I've seen people call it the Eurocrapper and other negative names. Its the same story, people with no experience in aerodynamics and flight mechanics making these comments on the aircraft because they have read a bias article or have misinterpreted literature describing the aircraft. Not to mention (for some people, not all) their own bias because its not an American aircraft. The same goes with the Europeans not liking the Raptor because its not an European Aircraft. But yet people have called it the Eurocrapper and there isn't much done, If anyone here makes a negative comment or questions the raptor in a negative way they get attacked. If i said it was the F-22 Craptor then I'd be attacked in all directions.

Idesof you seem to always be involved in Troll accusations. I've seen comments from you calling the Eurofighter the Eurocrapper, and saying ridiculous comments like Europeans can't build aircraft. If I said those things about the Raptor and America you'd call me a troll. I can safely say that your bias does get in the way of your posts.
Offline

checksixx

Elite 1K

Elite 1K

  • Posts: 1525
  • Joined: 20 Jul 2005, 04:28
  • Location: Langley AFB, VA

Unread post19 Oct 2006, 13:53

SpeakTheTruth wrote:
checksixx wrote:How's that Top Gun line go?..."Cough, Troll!"


Ok another troll accuser because of a negative view of the F-22.


You do realize that not only is he downing the F-22, but also the F-16 right? The way he worded his post sure sounded like he was just trying to stir up the hornets nest to me. If I'm wrong about him, which I hope I am, then I appologize.

-Check
Offline

SpeakTheTruth

Active Member

Active Member

  • Posts: 145
  • Joined: 26 Jul 2006, 09:11

Unread post19 Oct 2006, 14:44

checksixx wrote:
SpeakTheTruth wrote:
checksixx wrote:How's that Top Gun line go?..."Cough, Troll!"


Ok another troll accuser because of a negative view of the F-22.


You do realize that not only is he downing the F-22, but also the F-16 right? The way he worded his post sure sounded like he was just trying to stir up the hornets nest to me. If I'm wrong about him, which I hope I am, then I appologize.

-Check


If you think he is a troll, then just ignore him and do not post anything. Don't feed him, thats how you deal with a troll right? The difference in this thread is (and this is not about you Checksixx), is that people have accused him of being a troll to defend the Raptor and any other beloved aircraft he mentioned. The reason the troll accusations started here and in similar threads is that the accusers will then think everyone else who reads it will discard what the thread maker has said, because he is an apparent "troll".

All I can say is grow up, if you really belive someone is a troll then you simply ignore him, so you're not feeding him. When people reply with Troll accusations then thats more likely to cause arguments and take the thread off-topic.
Offline

Guysmiley

Elite 1K

Elite 1K

  • Posts: 1496
  • Joined: 26 May 2005, 19:39

Unread post19 Oct 2006, 14:58

checksixx wrote: If I'm wrong about him


Luckily enough, you aren't. :thumb:
Offline

Fighter_Mafia

Newbie

Newbie

  • Posts: 4
  • Joined: 18 Oct 2006, 20:40

Unread post19 Oct 2006, 16:14

First of all I won´t reply to those who call me troll or laughing, go home. Anyway, very disappointing to see such stupid reactions.

Raptor Claw:

You have no idea what the number is at Mach 1.0 - it could very well still be 5g. Why do you think the requirement was higher at Mach 1.5? These engines are designed to shine supersonic. Also, Mach 0.9 to 1.0 is a gain of about 45 knots (calibrated) - means more qbar, less AOA required for same 'g', less drag, etc...


By no means. From what I know, there´s no such thing as an airplane with more Ps at mach 1 than at mach 0.9. First of all at that speed you have already passed the cruise speed and the lowest drag point (when induced and parasitic drag are equal), so at this speed parasitic drag is increasing at a faster rate than the decrease rate of induced drag (yes propotionately it´s the same rate, but since the induced drag is a smaller portion of overall induced + parasitic drag, cutting it by half doesn´t mean too much against twice the parasitic drag. It´s just an example) . Furthermore, you have lots of drag in form of shock waves. This extra drag becomes weaker after mach 1.1 or 1.2. I´m no expert on the subject but we can agree on this.

No doubt that the ATF was optimized for supersonic performance, but a similar thing happens to any supersonic fighter - when they get truly supersonic they have more Ps than at transonic. Look at the F-16 and F-4 graphs:

http://www.f-16.net/f-16_forum_viewtopic-t-5487-start-0.html (BTW here you can see what is true progress from one generation of warplanes to another, even though the time from Phantom to Viper was less than from Viper to Raptor, and that it was a cheaper plane not several times more expensive like the Raptor).

I don´t know why but the effect increases with altitude - that is, the higher you are the less affects you the transonic and supersonic region and the more you re-gain when you get deep supersonic. Look at the 25k chart for Viper, it can in fact hold the same Gs at mach 1.5 than at exactly mach 1, and at 1.2-1.4 it holds more. Now take a higher altitude for a supersonic optimized plane and there you have the 1 G advantage for supersonic vs transonic.

What makes no sense is your statement, that ´´it could be 5g´´, that´s just non-sense. It´s hard to believe that it can jump from a common-place 3.7 Gs/mach 0.9 to an excellent 5 Gs later - and it´s plainly impossible if you´re talking of exactly the transonic region.

Hold on this: it is less than 3.5 G instead of the ideal 5g, and it´s no more than the 30-year-old tiny Viper does.

And where are you getting this data? I'm assuming that you got dog-house plots that you didn't include - that's fine, you don't need to. As an aside, the F-16 does not fly at 11G, so there is no way that data could be verified.


In the 5k chart you can visualy ´´plot´´ the trajectory of the 0 Ps line as it ´´disappears´´ beyond 9g - it almost touches the 11g line.

Anyway, if the Viper does 5g (in fact a little bit more) at 25k, it won´t fall 1.5 Gs or so in just 5k ft. I have to say again, the loss of energy becomes smaller with increasing height, and 1 G is not reached till 60k. The main point remains: the Raptor has no advantage, in fact with what we know it´s inferior to the Viper in this situation.

What's your point? That it can sustain slightly more g's at one particular point in the sky. Okay.


Below mach 1, this data and Raptor - Viper difference will vary, but not by much. The 10% Raptor disadvantage can be converted into a match or a slight advantage (it can also fall to a greater disadvantage, of course), they´re different aircraft. But this variations will be slight. All the way up to mach 0.95/50k, the Raptor is a common-place performer. 30 years ago it would be great, yeah, against Vipers which were 10 times or so cheaper by that time, and Eagles that were about 5 times cheaper.

And if I don´t use many performance points, it´s just because the heavy misinformation surrrounding this aircraft. There just isn´t available many performance data. And you haven´t speaked about the acceleration data, which corroborates the rest of the post: common-place performance, with acceleration somewhere between production and prototype Viper, and nowhere near its goal of super-agility and plenty of energy.

Mediocre? Mediocre? Did you just use the word mediocre in a description of the F-16?


No, no. I said that among all the Viper blocks, the block 15 is rather common-place or mediocre from the energy-maneuverability point of view. It´s definitely worse than the block 30, and possibly worse than any of the blocks with powerful engines due to lower thrust-to-weight. It´s also worse than the first blocks which had a smaller tail and were slightly lighter but had the same power. My point was, the data you see in the graphs, is not from the best performing F-16. There are better Vipers for the sustained-turn issue. Viper is one my very favorite airplanes.

All the data you have is 1-g roll rate


Eh?The chart doesn´t specify g-load, instead gives AoA - which gives you lift and in turn gives you Gs. So it essentially is for G loads. Yes, there can be additional changes when G load is involved (for example, the original Hornet wing was too weak and its roll rate suffered at high g, also at high q). But essentially it is this. Normally and up to a certain point, angle of attack and G go hand-by-hand.

If you did, you would have to tell a different story.....


This is plainly F-22 bias. It is you who have posted only opinions saying that the data I´ve compiled is meaningless. You have no clue on what is the true performance but Air Force claims (which I don´t remember saying the roll rate of the Raptor was better than Viper, by the way -in fact I don´t remember then providing many actual, substantial data aparte from the posted here).


As for the high AoA roll rates, I didn´t quite understand you. Yes, we assume that there are additional yaw movements - but how does that contribute to agility or roll rate? I frankly have no idea no this specific subject, all I´d heard was about yaw instability at hig AoA (which was the factor behind the roll rate decrease it I remember) but not that it was in benefit of agility.

I don´t know exactly how the increased weight would affect roll performance, but most likely it will degrade. The problem with YF-22 was not huge AoA, it was common-place angles where it could not match Viper - as opposed to the testimony of the test pilot. Note also that the test pilot can have mistaken and mis-recalled the roll performance of the Viper, without intentionally lying, but the result is the same - misinformation.

That's just it - it is a WHOLE BUNCH BETTER when you look at the system as a whole, and not a couple isolated performance points.


The point is, do you know with certainty what´s exactly the whole, what makes the Raptor so great? Or do you just belive what lockheed and the Air Force say?

Oh, but it does.


It´s bigger, has poorer visibility from the cockpit, and has worse subsonic roll and sustained turn performance. Definitely no.


Speakthetruh:

First of all, thanks :D :wink: You´re partially right. However, with the adequate information any outsider of the program can know its performance and other things. Also I´ve posted some actual USAF data. I think it´s better trying to understand and know within our limitations to determine just how good the aircraft is, than simply giving up and saying that it´s work for other people. And there´s a good deal of Raptor data which anyone can understand and needs to know - hey they´re spending our money so we deserve to know at least the main points of what´s going on.

By now, Riccioni´s claim seems to be confirmed - the Raptor has Eagle-like performance.


Now for all the forum:

Note the price goal. It was to be no more expensive than the Eagle - absurd claim wich was useful to sell the plane to Congress. One has to quote the Pentagon Paradox - there are only two phases for a major military program: too early to tell and too late to stop. Som 3 or 4 years ago, when it began to become clear that the Raptor was ridiculously expensive, Raptor advocates switched to the new point - that we have already spent to much money and now the airframes are in fact cheaper than building more legacy fighters.

It´s an empty claim. There are Gao reports specifying exactly how much money has the Raptor budget right now, it is slated to be completed with 63bn. Of this, 28 bn was for R+D. That leaves you with 183 jets for 35 bn or 191mn per fighter. This is way more than twice the 1984 statement in current-year dollars, but good enough compared to the total cost which is more than thrice the original goal.

This matches quite well with Gao statement that the new multi-year contract would increase cost:

http://pogo.org/p/defense/do-060701-f22a.html

We would point out, however, that the unit cost to procure remaining F-22As has increased 8 percent when comparing the fiscal year 2007 budget (using multiyear procurement) to the fiscal year 2006 budget (without multiyear procurement). The unit procurement costs to complete the F-22A program in fiscal year 2006 was $166 million per aircraft for 56 aircraft. The unit procurement cost to complete the program in fiscal year 2007 using multiyear procurement increased to $179 million for 60 aircraft.


F-22 advocates should check recent history. It is not that they´re so expensive because we build very few of them; the number of aircraft to be purchased progressively dropped because there was not enough money to buy them. This is the reason why we have gone from 700 to a mere 180 fighters.



The initial error in the program remains, because reaching the stated goals was impossible. If you have to be a fighter, you need to be a flying engine - that is, your engine is a good deal of your overall weight, it has to be so if you want good thrust-to-weight ratio. Also you need large wings for maneuverability and a very aerodynamically-optimized aircraft - this is not a transport. The problem when you add supercruise is that the fuel needed jumps form a 25-30% of the take-off mass, to 35% or above. Your fuel fraction has to be larger to accomodate supercruise missions. All this means that there is no place for luxuries or dead weight, everything has to be packed and lightened in order to combine supercruise and performance.

Twin engines, sophisticated avionics, perhaps even thrust vectoring, all point to an inefficient design with loads of dead weight (higher empty weight not constituted by engine or aerodynamics), meaning by dead that it does not serve the main mission of supercruise and performance. But these are small problems compared to the Uruk-hai: stealth. When you add RAM materials and a huge weapons bay, you add a lot of dead weight. There´s just not room enough. Making the airplane larger ´´to make room´´ is essentially useless for this issue, because the higher weight needs more fuel to keep the fuel fraction, larger perimeter needs more RAM materials so this as well goes proportional to overall weight, you need bigger engines, etc. There´s just no way of combining steath with supercruise and high performance. At least, so it is with the usual radar stealth favored by the Air Force - in fact such an aircraft would be bigger and hence less stealthy visually.

Guess what happened to the weight limit - similar to the fate of the cost limit:

http://www.f-16.net/f-16_forum_viewtopic-t-5487-start-0.html

"We were never able to design an airplane with a 50,000-pound takeoff gross weight that came close to meeting the Air Force requirements," Mullin admits. "After two years of hard work, we convinced the Air Force that it was not possible. The weight requirement was changed.

...

"We were almost 9,000 pounds off on gross weight and $5 million off on unit cost,"


So it was, the YF-22 was at 58k+ pounds, 22k of it being fuel. Right now the Raptor is at the very least 43k empty with about 20k of fuel. For this reason, the intended, idealistic 1.4 thrust-to-weight ratio never became reality. Now it is about 1.05, hence the difference between original requirements and nowaday requirements. For the very same reason, the fuel fraction which was 38 percent in YF-22 has dropped to about 30.


What´s really remarkable is that all these problems were totally predictable and avoidable. Since the set of unrealistic requirements, to the extremely long development process, passing by the competition between technology demonstrators, little or nothing was done right. The results are clear and were effectively predicted many years ago.

http://www.d-n-i.net/fcs/pdf/3_reasons_why_atf_not_into_emd.pdf

The sky-rocketed cost, the delays, the shrinking force size, the disappointments with aircraft supercruise and performance - all have come true. They Air Force knew that it was about to happen if they didn´t carry out things well yet they let this program go down the toilet direct to disaster.
Resolution to most of these problems is For All to tell The Truth despite what it may lead to - E. E. Riccioni
Offline

Raptor_One

Elite 1K

Elite 1K

  • Posts: 1092
  • Joined: 19 Aug 2004, 08:19

Unread post19 Oct 2006, 18:03

Does anyone here have time to read this $hit? :D
Next

Return to General F-22A Raptor forum

Who is online

Users browsing this forum: No registered users and 15 guests