One of the most imposing fighters ever built...

You would love me to say it's the Raptor right... but guess what, that's not the plane.

A couple of weeks ago I was given a book called Twenty-first century warplanes and helicopters After looking through the most important planes and started reading it I found out that the text about the Russian Su-27 "Flanker" sounded really promising, looking at the plane specifications and then comparing it with some of the best fighters today like the Eurofighter and the Raptor (only counting few) It became very clear to me that the Su-27 didn't a competetor when it came to speed, ceiling and thrust.

I do know that air-comat in the future will be all about BVR, stealth and missiles, and not about agility. but looking at the Flankers specifications I have to say that even the American president would have to admit that the Su-27 is engineering at the best.

The following text is an extract from the book Twenty-first century warplanes and helicopters.

Designed as a gigh-performance fighter with a fly-by-wire control system, the highly manoverable Su-27 is one of the most imposing fighters ever built. The first "Flanker-A" prototype flew on 20 may 1977 and entered service as the "Flanker-B" in 1984.The development of the Su-27 fighter was completed in the early 1980s, and the aircraft subsequently set mroe than 40 world records of altitudeand take-off speeds. It was a forerunner of an entire family of fighter aircraft, including the Su-27UB training variant, the Su-33 carrier-based fighter, the Su-37 multi-mission aircraftand the su-32FN two-seat spezialized version. The Su-27UB is a two-seated training version of the Su-27 wich first flew in march 1985. The aircraft is equipped to operate autonomously in combat over hostile territory, as an escort to deep-penetration strike aircraft, and in the supression of enemy airfields. The Flanker also provides general air defence on cooperation with ground and airborne control stations. The su-27 is in service with Russia, Ukraine, Belraus, kazakhsta and Vietnam, and is built udner license in China, where it is designated the F-11. A variant, the Su-20MK, has also been sold to india where licensed loca production began in 2000. There is no doubt that the Flanker is one of the most potent warplanes in service.

And if we are comparing the spefications, it is clear that the enignes of the Su-27 are without a match, same with speed and ceiling.

Su-27

Thrust: 12.500 kg (in each egnine)
Maximum Speed: 2500 km/h
Ceiling: 18500 m

F-22

Thrust: 15.909 kg (in each engine)
Maximum Speed: 1600-1800km/h
Ceiling: 16600 m

F/A-18

Thrust:14.545 kg (in each engine)
Maximum speed: 2082 km/h
Ceiling:15240m

EDIT: Correction about Su-27 thrust



[edit on 8-7-2006 by Figher Master FIN]

AL-31 engine produces 25 000kg of thrust?

combataircraft.com

This source say that AL-31F produces up to more than 12 000kg(27000-lb) of thrust, compared to F-119's 35 000-lb, which is more than 15 000kg. The F-16's F110-GE-129 and F100-PW-229 are also slightly better than the AL-31, producing 29,000-lb of thrust.

Originally posted by NotheRaGe
AL-31 engine produces 25 000kg of thrust?

combataircraft.com

This source say that AL-31F produces up to more than 12 000kg(27000-lb) of thrust, compared to F-119's 35 000-lb, which is more than 15 000kg. The F-16's F110-GE-129 and F100-PW-229 are also slightly better than the AL-31, producing 29,000-lb of thrust.

Good notice NotheRaGe...

yes, I checked this from a couple of web-sites and it seems that you are right. Strange that a book can lie so much


However it prooves that the plane can go much faster even though the engines are about the same...

Originally posted by Figher Master FIN
However it prooves that the plane can go much faster even though the engines are about the same...

The speed restriction on the the F-22 is mainly due to airframe materials. The F-15 could achieve Mach 2.5 with less thrust than both of them. With a weapons loadout the F-22 can achieve Mach 2 while the F-15 and Su-27 cannot. I also doubt that the Su-27 has a higher service ceiling than the F-22 as no one knows what it is yet.

[edit on 8-7-2006 by JFrazier]

Just to add, I doubt the Su-27 has a higher operational and absolute ceiling than the F-22. And the F-22 can out accelerate both the F-15 and Su-27 along with any other fighter in the sky.

Originally posted by NotheRaGe
AL-31 engine produces 25 000kg of thrust?

combataircraft.com

I think its purpose was to say combined thrust.

12,500 for each engine 2X = 25,000kg

Originally posted by chinawhite

I think its purpose was to say combined thrust.

He stated one engine, but nevermind. Same applies for the F/A-18 F-404. They only each provide more than 7000 kg (16,000-lb) each, and 14.545 kg only seems write for both engine. The F/A-18E/F would have been more popular if they have such powerful engines to go supersonic when flying low level.

Indeed the Flanker is a beautiful, agile and powerful aircraft.

Play Flanker 2.0. It is a simulation dedicated to the Su-27 and the Su-33, which is the naval version of the -27. All performance characteristics are real-world based, and it is by far the most realistic simulation I've ever played. The 400 page instruction manual alone I have used as reference material for a wide range of things.

The book clearly states it is 25.00 kg in each engine.

About the F-22 cervice ceiling, Indeed it is impossible to know. but you can always speculate, and 50.000 feet is a good guess.

And JFrazier you said "The speed restriction on the the F-22 is mainly due to airframe materials". Indeed, but it isn't built of lighter materlias, so it's useless to speculate about possible speeds.



[edit on 9-7-2006 by Figher Master FIN]

idont know much about, acceleration , speed and all, but lets face it no aircraft beats the sukhois as far as manouverability is concerned. i mean if theres a dogfight between between a raptor and a Su-30, i'll place my money on the sukhoi.
provided both pilots are equally well-trained.


for me >>> nothn like a sukhoi

Originally posted by vishu
idont know much about, acceleration , speed and all, but lets face it no aircraft beats the sukhois as far as manouverability is concerned. i mean if theres a dogfight between between a raptor and a Su-30, i'll place my money on the sukhoi.
provided both pilots are equally well-trained.

for me >>> nothn like a sukhoi

Indeed, myself I'am all western, I do like the F-22 even though some of you think I hate it, however I was truly impressed by the agility of the MiG-29 at an air-show couple of weeks ago.

[edit on 9-7-2006 by Figher Master FIN]

Originally posted by Figher Master FIN
The book clearly states it is 25.00 kg in each engine.

About the F-22 cervice ceiling, Indeed it is impossible to know. but you can always speculate, and 50.000 feet is a good guess.

And JFrazier you said "The speed restriction on the the F-22 is mainly due to airframe materials". Indeed, but it isn't built of lighter materlias, so it's useless to speculate about possible speeds.

The materials make a big difference because composities, used extensively in the Raptor, usually don't hold up to the high temperatures of Mach 2+ as well as metal(aluminum, titanium, steel). Without those restrictions, I have no doubt that the F-22 would have a faster topspeed than both the F-15 and Su-27. Program leaders have stated that it is way too easy for pilots to reach VMax at sea level.

Secondly, if I was speculating, I have seen reports of the serivice ceiling for the F-22 at around 60,000 feet as pilots have stated that they have been able to supercruise at that altitiude.

The Su-27 is much closer to the F-15 than the F-22 and Eurofighter. It's main advantage lies in its large airframe which allows it to carry more fuel than almost any other fighter. This also makes it much more visible to radars however. In terms of accleration I'd put it behing the F-22 and Eurofighter. The F-22 has been known to pull away from F-15s in military thrust while the F-15s where in afterburner.

BTW, the F-15s top speed is stated as being 2,655km/h. The F-22 also has a much better T/W ratio than the Su-27 only adding to its advantages.


[edit on 9-7-2006 by JFrazier]

Originally posted by vishu
idont know much about, acceleration , speed and all, but lets face it no aircraft beats the sukhois as far as manouverability is concerned. i mean if theres a dogfight between between a raptor and a Su-30, i'll place my money on the sukhoi.
provided both pilots are equally well-trained.

for me >>> nothn like a sukhoi

The Raptor will hold its own against an MKI. It's pitch and roll rates are higher than any of the Flanker series. The only time I see the Raptor having trouble would be very low speeds. Other than that, the Raptor will have much more energy coming in and out of a turn which is very important in dogfighting.

Right now I think the ultimate dogfighter would be the MiG-29OVT.

I was under the impression that the limiting factor in the F-22's top speed was the intakes, not aerodynamic heating. IIRC the designers chose to optmize the intakes for stealth, sacrificing some top speed in the bargain.

Originally posted by xmotex
I was under the impression that the limiting factor in the F-22's top speed was the intakes, not aerodynamic heating. IIRC the designers chose to optmize the intakes for stealth, sacrificing some top speed in the bargain.

As I have posted and intelgurl confirmed, the F-22 designers have pretty much rendered variable intakes obsolete. The intakes on the Raptor internally regulate airflow so they really don't have any affect on performance although they are designed for stealth.

That doesn't mean that it's not the intakes that limit the V-max, just that the designers chose to sacrifice absolute top speed for stealth by designing fixed intakes that work well over a wide range of speed ranges. The F-22's ability to supercruise makes absolute top speed less crucial - a plane that can go Mach 1.8 for an hour is effectively faster than a plane that uses afterburners to go Mach 2.5 for five minutes, even if the maximum attainable velocity is lower.

All design involves compromises, and the F-22 has sacrificed maximum speed for more useful sustained speed and stealth. The fact that it was (IMHO) a smart compromise doesn't mean it wasn't a compromise at all.

I think another limiting factor on the F-22 vmax is its sheer volume. as I said on another thread, its centre section is a huge box that accommodates all its main weapons load internally, this must have an adverse effect on velocity because of the sheer volume of air that has to be moved out of the way as it progresses. This is much more than the volume that has to be moved for an aircraft with external weapons and must have an adverse effect on top speed.

However this is only a feeling I have as I am no aerodynamiscist, maybe someone like kilcoo could clarify this for me?

MiG-31 is what you need if you want speed and ceiling out of a fighter, forget the rest.

Originally posted by JFrazier

The materials make a big difference because composities, used extensively in the Raptor, usually don't hold up to the high temperatures of Mach 2+ as well as metal(aluminum, titanium, steel). Without those restrictions, I have no doubt that the F-22 would have a faster topspeed than both the F-15 and Su-27. Program leaders have stated that it is way too easy for pilots to reach VMax at sea level.

Secondly, if I was speculating, I have seen reports of the serivice ceiling for the F-22 at around 60,000 feet as pilots have stated that they have been able to supercruise at that altitiude.

The Su-27 is much closer to the F-15 than the F-22 and Eurofighter. It's main advantage lies in its large airframe which allows it to carry more fuel than almost any other fighter. This also makes it much more visible to radars however. In terms of accleration I'd put it behing the F-22 and Eurofighter. The F-22 has been known to pull away from F-15s in military thrust while the F-15s where in afterburner.

BTW, the F-15s top speed is stated as being 2,655km/h. The F-22 also has a much better T/W ratio than the Su-27 only adding to its advantages.

[edit on 9-7-2006 by JFrazier]

Indeed, but it has restrictions so it is pointless to speculate about possible speeds.

Originally posted by Waynos

I think another limiting factor on the F-22 vmax is its sheer volume. as I said on another thread, its centre section is a huge box that accommodates all its main weapons load internally, this must have an adverse effect on velocity because of the sheer volume of air that has to be moved out of the way as it progresses. This is much more than the volume that has to be moved for an aircraft with external weapons and must have an adverse effect on top speed.

However this is only a feeling I have as I am no aerodynamiscist, maybe someone like kilcoo could clarify this for me?

Yes, everything is packed in one place. But then again i doubt that it would be better to have the weapons external, like you and Fred discussed in an other thread with the Super Hornets carrying 12 (correct me if I'am wrong) external missiles, that has to create som friction.

Yes FIN, that is a source of drag but the way I see it is that for a plane to move through the air a certain volume of air has to get out of the way to accomodate it, if you see what I mean. The Raptor has to shift a greater volume of air by comparison with other aircraft because all its weapos are contained in a box so the raptor is also hauling the air all around the weapons themselves that is contained within the fuselage around with it, requiring a greater volume of air to be shifted out of its way.

here is a crude diagram I made to try and explain what I mean, the upper Waynos F.1 has external; weapons which create drag but is itself a quite slender design, the lower waynos F.2 however carries its weapons internally, this gives it good LO and low drag but requires a more voluminous fuselage in which to accomodate them. The total frontal volume (including weapons) on the F.1 is therefore considerably lower than it is for the F.2.

This is what I mean by a design compromise that possibly limits the max speed of the F-22, or any other fighter with internal weapons.



This was why combat aircraft designers moved *away* from internal weapons carriage in fast jet era, despite it being commonplace in WW2 and also why the F-22 requires such hugely powerful engines in relation to its size in order to supercruise. It is also why Concorde had to have 4 abreast seating and why there has never been a widebody SST

[edit on 11-7-2006 by waynos]