Forum: F-22A Raptor

Joined: Dec 16, 2005 - 12:54 PM Posts: 0 Status: Offline

Thanks snypa777 Wink

I was not angry or anything with locum. After all as I said I love you all a lot. Cool

KALH TYXH KAI SE SENA FILARAKO, SYNEXISE NA GRAFEIS KAI ESY

(TRANSLATION from Greek: Good luck to you little mate as well. Keep up posting as well).

Laughing

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Dear Thodoris,
I did not intend to attack you personally, I was just trying to defend my position. I am a soldier, that means that I communicate directly, briefly, sometimes (very) rude/ agressive manner, I hate to give up, just keep on going until the end. Your posts are long, but they are well-written, polite and considerate, so keep on posting boy.

Joined: Dec 16, 2005 - 12:54 PM Posts: 0 Status: Offline

locum, my little friend thanks for your post and kind words also.

You know I was also a soldier, sailor to be more exact, so I know the type of language you are talking about and I can assure you that I can speak it too !

So it is fair to say that I like your posts a lot as well so keep on posting boy as well.

Thodoris. Thumb

WHY USAF NEEDS F-22A ~ PERSONAL OPINION

1. For the pride of Great USA, USAF must always have the most superior fighter on earth that will defeat any other fighter in the world in every aspect for as many years as posible.

2. Any exchange ratio that is less than 10:1 in A-A combat is humiliation to the greatness of USAF.

3. The life of USAF pilot the Great is much, much, much........more precious than any other fighter pilot in the world.

F-15C v.s EF-2K v.s F-22A

EMPTY-WEIGHT：
F-15C：12,973 kg ~ 13,427 kg（With AN/APG-63V2 AESA radar）
EF-2K：11,000 kg ~ 11,150 kg
F-22A：18,144 kg ~ 19,489 kg

STANDARD TAKING-OFF WEIGHT FOR A-A MISSION：
F-15C：20,350 ~ 20,830 kg
EF-2K：17,250 ~ 17,400 kg
F-22A：27,216 ~ 28,125 kg

WING-AREA：
F-15C：56.48 m2
EF-2K：50.00 m2
F-22A：78.03 m2

T/W，AB：
F-15C：1.038~1.062
EF-2K：1.055~1.065（May be increased to 1.113~1.172)
F-22A：1.129~1.300

T/W，MAX. MIL：
F-15C：0.639~0.654
EF-2K：0.703~0.710（May be increased to 0.808~0.817)
F-22A：0.822~0.850

WING-LOADING：
F-15C：360.30~368.80 kg/m2
EF-2K：345.00~348.00 kg/m2
F-22A：348.79~360.44 kg/m2

SERVICE CEILING：
F-15C：60,000 fts
EF-2K：62,000~65,000 fts
F-22A：70,000 fts

TAKING-OFF：
F-15C：900 fts
EF-2K：less than 900 fts
F-22A：800 fts

LANDING：
F-15C：3,500 fts
EF-2K：1,640 fts

FERRY-RANGE：
F-15C：5,745 km（6,103 kg internal fuel + 4,423 kgCFTs fuel + 5,395 kg tanks' fuel）
EF-2K：2,600 km（4,996 kg internal fuel ）
EF-2K：3,706 km（4,996 kg internal fuel + 1,000~1,500 L tanks*2）
F-22A：2,728 ~ 3,500 km（8,300~9,300 kg internal fuel ）

FLIGHT-ENVELOPE, 1G:

Fighters: F-22A RAPTOR／EF-2000 TYPHOON／F-15C EAGLE
Sea-level: 0.15~1.21 Mach／0.15~1.15 Mach／0.15~1.00 Mach
10,000ft: 0.15~1.40 Mach／0.19~1.40 Mach／0.15~1.10 Mach
20,000ft: 0.18~1.75 Mach／0.22~1.65 Mach／0.20~1.30 Mach
25,000ft: 0.20~2.00 Mach／0.28~1.85 Mach／0.25~1.45 Mach
30,000ft: 0.25~2.00 Mach／0.30~2.00 Mach／0.30~1.60 Mach
40,000ft: 0.30~2.00 Mach／0.35~2.00 Mach／0.40~1.76 Mach
45,000ft: 0.40~2.00 Mach／0.40~2.00 Mach／0.55~1.70 Mach
50,000ft: 0.50~2.00 Mach／0.45~2.00 Mach／0.65~1.60 Mach
55,000ft: 0.60~2.00 Mach／0.50~2.00 Mach／
60,000ft: 0.70~2.00 Mach／0.75~1.85 Mach
65,000ft: 1.00~2.00 Mach／0.88~1.70 Mach
67,500ft: 1.20~2.00 Mach／

FRONTAL RCS:
F-22A：0.00015 ~ 0.00060m2..........1~4 --> 1.00~1.40
F-35A：0.0012 ~ 0.0015m2...........8~10 --> 1.68~1.78
EF-2k：0.05 ~ 0.25m2...........333~1666 --> 4.27~6.39
F-15C：10 ~ 25m2...........66666~166666 --> 16.07~20.21

Radar Detection Range:
F-22A, APG-77：200~230 km for RCS 1m2 target.......Score: 222~256
F-35A, APG-81：160~185 km for RCS 1m2 target.......Score: 167~205
F-15C, V2/V3：144~185 km for RCS 1m2 target.........Score: 160~205
EF-2K, Captor：185~280 km for RCS 5m2 target........Score: 137~208
F-15C, APG-63：160 km for RCS 5~10 m2 target........Score: 100~119

So, what if the Raptor were to cost $500M a copy? Would you still buy it?
How about $1B? $1.5B? 2B?
At what point does its cost remove so much of our national combat capability in other areas that we would scream "Uncle!"?

Here's why the F-22 is needed ~ The answers from USAF

http://www.defense-aerospace.com/cgi-bi ... le=release

fezt wrote:

Raptor fighter pilot,
i have read your post, very nice indeed (really).
in short:
the Israeli fighter jocks who fly both the f-15I (e) and the f-16I (52+) say that in almost any war scenario, they would take the f-16I.
about your remarks of Israel not doing as well if they had f-16 instead of f-15, we will never know, what we do no know is that the f-16 got more victories then the f-15 and they were never hit in a dogfight (the f-15 got a hit from an enemy fighter, lucky for them the missile didnt explode, bet the f-15 got a direct hit and managed to get home safely).

I will not address the F-22 Vs F35 any more, for the reason that i did enough in the past and i do agree that we will only know the real truth in the future.
i am sure that the f-16 can do almost anything the f-15 can in less cost, about the new jets, we will wait and see.
cheers.
fezt.

Have you ever seen an F-15 in action? Better yet have you even been to an airshow? You don't see many fighters take off in less than 1000ft, pitch straight up and go out of sight in afterburner. This is something I've seen many F-15's do, but yet to witness a F-16. When it comes to thrust to weight ratio the F-15 is the clear winner. If you can out climb, out perform and have better radar systems, well what else can I say you have a distinct advantage.

Don't get me wrong the F-16 is a wonderful airplane, heck this entire site is devoted to it. You fight the fight your airplane was designed for. You use your advantages to exploit your opponents weakness.

The F-22 has a kickass radar, superior communications, STEALTH, thrust vectoring for those turning battles. We should all thank the lucky stars we have this aircraft and not the enemy, because trust me the Su-29 and all its variants are extremely capable airframes

Okay, in what dream world does the F-15 have a higher TTW ratio than an F-16? Which F-15 and which F-16?

Dream world? Hardly. My math for comparable aircraft (C models and clean configuration) I get 1.12 for the F-15 and 1.09 for the F-16. When you compare the thrust and the weights they are very comparable. The best the F-15 and the F-16 will ever do on TTW will be their respective A models. I know....the newer jets have more thrust but guess what? The newer blocks of jets weigh more, thats why they need more thrust, its that or the jets get doggier as they get that middle age spread. Now with all things being fairly equal in the TTW arena when you factor in variable geometry intakes on the F-15 its a much different ball game. The F-15 WILL break the speed of sound going straight up. As much as I love the F-16 (I have worked both BTW and you can throw in the A-10 and as of recent the F-22) it doesnt have the verticle climb prowess that the Eagle does.

mark wrote:

Dream world? Hardly. My math for comparable aircraft (C models and clean configuration) I get 1.12 for the F-15 and 1.09 for the F-16. When you compare the thrust and the weights they are very comparable. The best the F-15 and the F-16 will ever do on TTW will be their respective A models. I know....the newer jets have more thrust but guess what? The newer blocks of jets weigh more, thats why they need more thrust, its that or the jets get doggier as they get that middle age spread. Now with all things being fairly equal in the TTW arena when you factor in variable geometry intakes on the F-15 its a much different ball game. The F-15 WILL break the speed of sound going straight up. As much as I love the F-16 (I have worked both BTW and you can throw in the A-10 and as of recent the F-22) it doesnt have the verticle climb prowess that the Eagle does.

I have the numbers I crunched today at the office and they are different from yours. However, they are not with me right now but I'll post them tomorrow. Their respective TTW is actually almost exactly the same (Block 50 F-16, 29,000 lb. thrust engine, full internal fuel vs. F-15C, 2 X 24,000 lb. engines, full internal fuel). I obviously know the later models weigh more. In fact, the F-16, in percentage terms, gained a lot more weight than the F-15 over time. Notwithstanding, late models of both have almost exactly the same TTW. Now, anyone can jump in here and correct me if I'm wrong, but at subsonic and transonic and low supersonic speeds, the F-15's VG intakes do not make one iota of difference in terms of thrust, drag, accelaration or climb rate. Moreover, it is my understanding that the F-16 can in fact break supersonic climbing straight up. Again, anyone can jump in here and correct me if I'm wrong.

Elite 1K Joined: Aug 19, 2004 - 09:19 AM Posts: 1092

I'm not quite sure how people are doing their calculations, but the whole T/W ratio argument isn't nearly as clean cut as people make it out to be. First off, T/W ratio is somewhat meaningless when you talk about the uninstalled, sea level static thrust of the engine in max AB. Put it in the aircraft and you need to build up a little bit of speed at sea level before you start to see actual net thrust values equal to or greater than the uninstalled test numbers. We're talking about Mach 0.5 +/- 0.1. Once you start moving though, the aircraft begins to generate drag and you no longer have simply T/W. You have (T-D)/W. D = drag, and when you double your velocity, your drag increases by a factor of 4. I can say for a fact that the F-16 has, in general, a lower drag coefficient than the F-15C in the subsonic regime. Not much lower really... they're very comparable. Let's call them equal though. In that case, the F-16 is producing a little under half the drag of the F-16 because its reference area is 300 sq. ft. versus 608 sq. ft. for the F-15.

Luckily for the F-15, it has twice as many engines as the F-16. In terms of T/W ratio, the best performing F-15 is the F-15C with F100-PW-220 engines. The best performing F-16 in terms of T/W ratio is actually the F-16C Block 30 or the F-16C Block 50. The difference between the two in the subsonic regime is minimal. The Block 50 does better above the Mach... especially at low altitude. So let's just take the Block 50 F-16C and the F-15C w/PW-220 engines. Consider both aircraft in the clean configuration with full internal fuel. The T/W ratio numbers favor the F-15C by a very small amount. The F-16C is going to generate less than half the drag of the F-15C. The F-15C's two engines, in general, put out a little more thrust than its fully fueled clean weight at low speed/altitude. The same is true for the F-16C Block 50, but it has a slightly lower T/W ratio (both are above 1.0) than the F-15C at low speed/altitude. It is going to be generating slightly less than half the drag of the F-15C, so at low speed/altitude you will have (T-D)/W nearly equal for both aircraft.

Now for the kicker... neither the F-15C or F-16C have engines whose thrust goes up by a factor of 4 everytime you double the velocity. Sure... AB thrust generally increases in these aircraft as speed increases. At sea level above the Mach, thrust is going to be WAY bigger than it was at Mach 0.2 let alone static values. We're talking as much as a 50% (or more!) increase at sea level from Mach 0.2 to Mach 1.2. However, we're not talking about an increase that is proportional to the square of the velocity. Thrust does not quadruple as the airspeed doubles. But drag does. Drag increases faster than thrust.

So... why does the F-15C take off much quicker than the F-16C Block 50 (or any other block)?? Quite simply because it generates more lift with its big wing (more than double the F-16's reference area). To get off the ground, you have to generate more lift than your weight. A fully fueled F-15C in a clean config is not nearly twice the weight of a fully fueled F-16C block 50, also in a clean config. But it's going to generate more than twice as much lift for sure. This lift advantage gives the F-15C a shorter take-off role. The (T-D)/W ratios are about the same for the Block 50 F-16C and F-15C as they're going down the runway and about the same once they go wheels up and begin accelerating. However, the F-15C does not generally perform as well as the F-16C at low and medium altitudes because of its huge wing. This huge wing makes (T-D)/W less and less impressive for the F-15C at these low/medium altitudes. At some altitude this trend begins to reverse, and the variable geometry inlets of the F-15C enable it to keep going past Mach 2 where the F-16C simply hits a wall.

At low altitude and slow speeds though, the (T-D)/W ratio is, for all intents and purposes, equal for the F-15C and F-16C block 30 or 50.

First of all, let me thank you for this excellent post. It was really needed here.
I really, really don't want to be nit-picky here, but I do think one minor clarification is in order:

Raptor_One wrote:

and when you double your velocity, your drag increases by a factor of 4.

This is true only in certain conditions. Specifically, if you can assume that drag coefficient (Cd) is constant, which you usually can't do. Assuming a conventional drag polar, Cd will increase as lift coefficient (C_lift) increases - and visa versa. As airspeed increases (assuming constant weight and load factor), the required C_lift will reduce, and Cd will reduce as well, so you (typically) won't see the full factor of four increase.

Of course, for the vertical climb case the factor of 4 pretty much works because C_lift more or less stays at 0.0 the whole time and Cd should pretty much stay constant (at Cdo). Of course, if you are talking about passing the Mach while climbing, the whole game changes again as Cdo changes.

But your point is unchanged, as indeed:

Raptor_One wrote:

Drag increases faster than thrust.

Raptor_One wrote:

At low altitude and slow speeds though, the (T-D)/W ratio is, for all intents and purposes, equal for the F-15C and F-16C block 30 or 50.

Exactly my point, and I agree with most of what you write except this: during a vertical climb (a rather dumb way of gaining height, by the way, even if your TTW ratio is greater than 1), wing lift becomes irrelevant. Its drag, however, does not. If what you write above is correct, the Block 50 should have an F-15 in a vertical climb easy.

Elite 1K Joined: Aug 19, 2004 - 09:19 AM Posts: 1092

Raptor_claw wrote:

First of all, let me thank you for this excellent post. It was really needed here.
I really, really don't want to be nit-picky here, but I do think one minor clarification is in order:

Raptor_One wrote:

and when you double your velocity, your drag increases by a factor of 4.

This is true only in certain conditions. Specifically, if you can assume that drag coefficient (Cd) is constant, which you usually can't do. Assuming a conventional drag polar, Cd will increase as lift coefficient (C_lift) increases - and visa versa. As airspeed increases (assuming constant weight and load factor), the required C_lift will reduce, and Cd will reduce as well, so you (typically) won't see the full factor of four increase.

Don't worry, you're not nit-picking. I was trying to explain things as simply as I could without oversimplifying. I don't know if you've ever played the flight sim Falcon 4.0, but I helped put together some high fidelity F-16 flight models for one of the later "community versions" of the sim. The other primary developer and I put out a detailed manual with the flight models that showed the complete range of input data (CL vs. AoA, CL vs. CD, installed thrust, etc.) as well as output performance data including EM diagrams. To make a long story short, my experience making these flight models (as well as the EM diagram generator I coded in Matlab) gave me a thorough understanding of all the variables in play beyond what I learned studying aerospace engineering in college.

You've obviously got the same (or better) understanding of the aerodynamic coefficients, flight performance equations, installed thrust behavior, etc. No comparison is simple unless you use a computer to compare two aircraft in a specific area like (T-D)/W ratio. I'm not even sure what the best comparison method would be right off the top of my head. Like you say, the faster you go in level flight, the lower your 1G AoA will need to be. And hence you'll be flying closer and closer to CDo (CDmin is probably a more accurate term for real-world aircraft though). At low calibrated airspeed, neither the F-15 or F-16 are going to be flying at CDmin. Then again, there's an area in the drag polar around the exact CDmin where CD doesn't vary much with CL. But then you run into compressibility effects as the Mach number nears 1.0 and CDmin begins to shoot way up. CDmin generally goes up by about 0.02 from subsonic to supersonic conditions, right? And CDmin for the F-15 and F-16 at subsonic conditions is around 0.02 +/- 0.002, right? That transonic regime sucks bigtime... hehehe.

Quote:

Of course, for the vertical climb case the factor of 4 pretty much works because C_lift more or less stays at 0.0 the whole time and Cd should pretty much stay constant (at Cdo). Of course, if you are talking about passing the Mach while climbing, the whole game changes again as Cdo changes.

It's pretty hard to say which of the two aircraft would climb straight up faster. It probably depends on what speed and altitude each plane entered the vertical climb, and how far the vertical climb went up to. One would simply have to write up a simulation to determine the outcome. Looking at snapshots of each aircraft at one single altitude and one single airspeed doesn't convey the entire picture. Another thing I'm pretty sure of is that neither the F-15 nor F-16 can accelerate through Mach 1 in the pure vertical when starting off in the vertical at a very slow speed. There's no way either of those aircraft are going to take off, raise the gear, and immediately go vertical and THEN accelerate up past Mach 1. Now perhaps if you allowed both fighters to get up to about Mach 0.9 or better and then pull up into the vertical, they'd be generating enough thrust to continue accelerating past the Mach. I doubt either one would get much past Mach 1.0 though, and they'd quickly reach an altitude where T-D became less than weight and poof... right back to subsonic speeds. There's really no point in trying to climb like this anyway... it's certainly not efficient.

Quote:

But your point is unchanged, as indeed:

Raptor_One wrote:

Drag increases faster than thrust.

Yeah.... that's certainly always true. In addition, thrust will eventually start to decrease if you get fast enough due to ram effect. Drag just keeps on going up though. In addition, all but the oldest F100 series engines (and all of the F110 engines) will begin to spool down the fan RPM at insanely high (stagnation?) pressure levels to prevent compressor discharge pressure from getting too high and blowing up the engine/aircraft. Thrust can still continue to increase for a while, but not at the same rate so to speak. Anyway... I think we both agree that these types of comparisons are much more involved than simply looking up a fighters fully fueled gross weight and its powerplant's uninstalled SLS AB thrust and plugging the two numbers into a calculator. That kind of simplistic T/W ratio is practically useless when it comes to real world comparisons of two different aircraft.

Elite 1K Joined: Aug 19, 2004 - 09:19 AM Posts: 1092

idesof wrote:

Raptor_One wrote:

At low altitude and slow speeds though, the (T-D)/W ratio is, for all intents and purposes, equal for the F-15C and F-16C block 30 or 50.

Exactly my point, and I agree with most of what you write except this: during a vertical climb (a rather dumb way of gaining height, by the way, even if your TTW ratio is greater than 1), wing lift becomes irrelevant. Its drag, however, does not. If what you write above is correct, the Block 50 should have an F-15 in a vertical climb easy.

I was only talking about wing lift in terms of take-off run. The F-15 can generate more total lift as it rotates and thus lift off sooner than the F-16. It's also going to generate more lift due to ground effect if I'm not mistaken (compared to the F-16). As for a vertical climb, I have no idea which aircraft would climb to a certain altitude faster in the pure vertical. It all depends on the altitude and airspeed they start off at in the horizontal before they pull into the vertical. I don't know how to visualize the performance of these two aircraft in my head when you have so many variables changing during the process of a vertical climb. Velocity will change, density will change, and installed thrust will change. I'm probably forgetting something else too. Regardless, with those 3 variables changing during the climb (assuming you don't get so fast that CDo starts increasing too), you need to work out the differential equations. It's a computer simulation... not something you'd want to do by hand. In fact, this is exactly the kind of problem that computers were built to solve.