How dare you call sferrin “a great fool”!!! shame on you!!……and stop arguing with yourself, makes you look stupid.

:rolleyes: :p 🙂

Does anyone have official figures for the Su-27UB fuel and an explanation of the range decrease, possibly:
1) Higher drag of the two seat cockpit and the 1500 kg weight?
2) There is a decrease in Su-27UB internal fuel? Looking at images it does look like the second seat eats into fuselage space, so I could believe this.

The official figure for the Su-27UB seems to be 9400 kg–the same as that of the single-seater. This appears to have been accomplished by raising the rear cockpit quite a bit, sort of placing it above the existing fuselage, more or less preserving whatever fuel tanks and other equipment that were already there. The increase in volume and frontal area results in significantly reduced range, going by the published figures, for the same internal fuel capacity due to higher drag (the weight increase probably matters much less), which would logically seem to affect acceleration as well.

Janes has 6600 of the 11775 litres being normal operational fuel load. “Higher figure represents internal auxiliary tank for missions in which maneuverability not important”

That’s a bit of an oversimplification, assuming that the “auxiliary” fuel is burned first in order to reach the “normal” load and regain full maneuverability. At the very least, I would be shocked if the fuel system worked any other way.

Brasseys has 9400 kg of which 6000 kg is normal and the remaining 3400kg is an ‘internal auxiliary tank’.

I kind of doubt that it’s just a specific tank because I’ve seen this figure change over time in steps from 6000 kg down to 5270 kg. Unless anyone knows otherwise, the figure seems to correspond roughly to a total takeoff weight, including a full load of AAMs, that gives the Su-27 and its derivatives a 1.0 or higher thrust/weight ratio. In this case, the reason that the “normal” fuel load kept getting smaller would be that the airframes of various derivatives have grown somewhat in weight over time. Admittedly, I don’t know for sure whether this is true, or just a convenient but coincidental explanation. There has to be some reason for it, though.

UB or not UB?
[ATTACH]160140[/ATTACH]

It’s not the UB, and the easiest way to tell in this case is the shape of the tips of the vertical stabilizers.

Of course it is a powerful jet with a very advanced manoeuvrable capability and today still have a stealth capability – but is it worth its price when stealth is not an insurance any longer?

There are no absolutes with regard to stealth. For now, it allows true VLO aircraft the first shot in virtually all engagements, but even if this advantage will someday erode, hypothetically speaking, having very small signatures would still help in other ways, such as making ECM more effective.

You can’t win in a dogfight even if you have a stealth aircraft like F-35.

It can still help some–foreign pilots participating in Red Flag claim that the F-22’s signatures confound their weapon systems even when they’re within visual range. Weapons aren’t perfect, either, and it’s reasonable to expect diminished PK against stealth aircraft.

You can’t use a so advanced aircraft fully without an operator in an extra seat.

This depends on how much the avionics can help out, which is a lot more now than it has ever been in the past.

AESA has the possibility to pick up every stealth aircraft when using a right frequence planning and if you are using the right electronical countereasures equipment.

It’s possible to detect any stealth aircraft, but it’s still going to be much harder to detect, track, and shoot it down when you take into account everything that goes into electronic warfare.

So you’ve got Jackie Chan in an empty warehouse at night with the lights off shining a flashlight around and you’re up on a balcony with a sniper rifle and night vision goggles. Who would you rather be? :p

Chuck Norris. 😀

btw, what do you think of roe restrictions? in practically every recent conflict, us fighters have engaged well within their armament envelope, just to be sure of the target, what of the jsf’s stealth then? isnt it a risk that it’d be detected?

I suppose they could sneak up behind the bogeys, in that case, circumstances allowing, although I’d much rather be in an F-22 if it comes to that.

or do the apg-77,81 etc have some new fangled “for sure” nctr tech..?

From what I’ve been hearing and reading, the F-22 is exceptional at accurately identifying targets. Dozer, for one, is convinced that the half-hour-long encounter he had with MiG-29s–spent mostly trying to get an ID and clearance from the AWACS–would have been over in seconds had he been flying an F-22. Although ROE is not up to line pilots, it seems that they have a lot of confidence in the F-22’s systems.

the F-35 will be a excellent performer within WVR’s Arena. Yet, it will rarely happen…………..First Look, First Shot, and First Kill!:diablo:

Oh God, not again.. I was pretty pi$$ed off by this utterly cheap Hollywood phrase with the Raptor,

The phrase speaks the truth about what every good pilot should try to accomplish with his fighter. It’s just that the F-22 and presumably the F-35 help make this task stupidly easy for their pilots.

there is really no need to bring it up with the 35, as well… :rolleyes:

Yes, there is no need because everyone should have realized this by now. 🙂

Flanker pilots often have to use differential thrust in order to stabilize the aircraft during high-alpha maneuvers, while there is no such need with the Raptor, due to its superior aerodynamics.

Blame it on FCS, not aerodynamics..

The Raptor’s FCS does not use differential thrust (or differential vectoring, for that matter), as it still has more than enough aerodynamic control power to stabilize at virtually any angle of attack and low speeds. The Flanker, on the other hand, becomes unstable much above 35-40 degrees (at least I read this in Aerospace during the early 1990s as a quote from a TsAGI researcher, and it would help explain the limiter), although as we’re all aware, it is capable of spectacular transient maneuvers at high alpha. If Su-27 pilots could use roll inputs to the FCS to stabilize like the F-22 uses differential tail, then I suppose they would, but pilots say they have to use differential thrust (from various articles in AvLeak and other publications–if I still had links or dates, I’d gladly give them to you, but I’m not making this up).

It may seem as though I’m trying to make too big a deal out of this, and truthfully, I am :), but the point is really to counter years of people claiming that the F-22’s aerodynamic design would necessarily be inferior to that of other fighters, let alone the Su-27, as a result of stealth. Looks like it isn’t, and that’s an understatement.

The f35 is being designed to be as agile as the f16,

This was meant in terms of climbing, turning, and acceleration, by the way.

do you really see the f16 outperforming the Eurofighter ?

No, but the F-35 will handily outperform both in the strike role in terms of payload over range.

Yes thats true about the T/W

And that’s all that is germane to my arguments. 🙂

but it does say in the most “important” fields they are superior here’s the quote, ” The US Air Force claims the F-15C is in several respects inferior to, or at best equal to, the MiG-29, Su-27, Su-35/37, Rafale, and EF-2000, which are variously superior in acceleration, maneuverability, engine thrust, rate of climb, avionics, firepower, radar signature, or range.”

It’s a fair statement to make in non-specific terms, and I agree with the USAF that more F-22s should therefore be procured. The latter is precisely why they originally made this statement, which was either quoted or paraphrased on the FAS website. Of course, then when Boeing complains about the USAF putting down a fighter that they’re trying to sell abroad (in its more advanced forms), I’m sure that the USAF will put in a good word for it privately to other air forces. They’ll say that the new AESA and avionics are top-notch (true) and the upgraded (IPE) engines give it power superior to that of potential adversaries (also true), but to the public, the Pentagon, and the Congress they will say that the beat-up old F-15 (earlier variants) is outdated and only the F-22 will be good enough. It’s a bit of doublespeak, but I don’t blame them for trying.

Besides, if the USAF were so worried about 24 Su-27SMs, they might send the 100+ F-22s they currently have against them. 🙂

Well thats where the topic went and I stand by my posts, and I assue you Russia’s airdefence network (which there’s non in the world like) will be more than able to shoot everyone of them down, U.S. stealth is soo “overexagerated” but that another topic lets not discuss it on this thread.

That’s the spirit! And I disagree with an equal measure of baseless confidence! Take that! Oh, yeah? Yeah! 😀

More refined “aerodynamicly” is what makes it “leaner” than the F-15.

My choice of the term “leaner” refers to lower structural weight and less internal fuel, which is analogous to a person with smaller bones and less fat. Given the Su-27’s leading edge flaps and other more modern aerodynamic features, it undoubtedly has an advantage in maintaining energy during hard turns, but I doubt it’s much slicker, if at all, while merely cruising (additionally, the Su-27 will have to burn fuel at a faster rate during actual combat). The main difference would be in the additional drag from the F-15C’s external tanks, of course, at least before they are dropped. According to the figures you quoted, carrying drop tanks all the way yields a maximum range of 4445 km compared to 4000 km for the Su-27, despite the extra drag. Dropping the tanks, whenever that becomes necessary, further improves on the F-15C’s range advantage (as long as they aren’t dropped too early, although in that scenario it would matter less anyway).

My comparison was limited to the merits of external fuel and the relative power of the two aircraft. Somebody suggested that the Su-27 is more powerful than the F-15C, but the opposite is actually true in most cases in terms of T/W.

Not according to the U.S.A.F. http://www.fas.org/man/dod-101/sys/ac/f-15.htm

Read their statement again carefully–they said that a bunch of modern fighters are “variously superior” in a bunch of different aspects of performance. This does not imply any specific comparisons, such as the Su-27 having a higher T/W than the F-15C, and it certainly does not mean that all of these fighters are superior in all respects to the F-15C because that would be a lie. The real point was to make a broad statement about the need for the USAF to upgrade.

Yes the 18 F-15’s that have AESA/JHMCS’s are more formadible but not against the 24 Su-27SM’s.

A lot of different things are going on right now, and people in various organizations are trying to decide upon the best upgrade path. The topic at hand was how the F-15C hypothetically compares to the original Su-27, not how one force structure compares to another, and the same applies to comparing the upgraded F-15C to the Su-27SM. Besides, if the USAF were so worried about 24 Su-27SMs, they might send the 100+ F-22s they currently have against them. 🙂

It’s aerodynamic design is 1 of the features that helps “cuts” the fuel burn rate, from a normal fighter with another design.

It’s that special and unique, huh?

The external fuel figure for the F-15C here looks strange–why should it be different from that of the F-15A? To me, it looks about right for two conformal tanks, but I’m talking about two external 610-gallon tanks (at 6.7 lbs/gallon for JP-8).

It may look strange to you but not to: http://www.aerospaceweb.org/aircraft/fighter/f15/

What’s your point? The website wasn’t specific at all (deficiently so in this case), but I believe that I figured out what their numbers really meant and stated it. The numbers we use have to make sense no matter what the source.

Ah, this means that the Su-27 carries around a bunch of space that it supposedly doesn’t use all of the time. Obviously, this is difficult to reconcile with the USAF doctrine of loading tactical aircraft full of fuel for every combat mission (you never know when it might come in handy).

Wrong during actual patrols/comabt practices it filled.

This makes perfect sense to me, but then why is there the notion of a “normal” (as in usual, as in most common) internal fuel load at all? If you’re right, then the answer must be the other possibility I had brought up: marketing hype. This hype has fooled plenty of people over the years. The Su-27’s design is still a great and extremely versatile design regardless, but it’s not quite everything people commonly believe that it is–like all designs of a given level of technology, there are tradeoffs and compromises, and there’s nothing wrong with that.

MiG-23MLD, those are some good points about the strengths of the Su-34. 😎 Does it still have a rear-facing radar in that oversized stinger?

Comparing the fighters directly while loaded with full internal fuel is more problematic because the F-15C is a significantly leaner fighter, while the Su-27 is relatively heavy with internal fuel at takeoff.

LEANER?

Yes, going just by the numbers–internal fuel only with no weapons–the F-15C has a T/W ratio of approximately 1.14 while the original Su-27’s is approximately 0.97; also, the F-15C’s fuel fraction is 0.328 while the Su-27’s is 0.365. Therefore, the F-15C is a “leaner” fighter at the time of takeoff, sacrificing range performance with internal fuel for power.

With those bulging scabbed on extra fuel tanks all over it?

Colorfully described, but irrelevant because I was describing the difficulty of comparing these two fighters directly using internal fuel only, given their different design philosophies. Representative combat scenarios have to be used so that the F-15C is not unfairly penalized for having a shorter range on internal fuel and the Su-27 is not unfairly penalized for having a lower T/W. Doing so gives us a clearer view of the engineering tradeoffs inherent in both designs.

Aerodynamically the Flanker is a much better aerodynamic shape than the Eagle any day.

It sure seems to be in many ways, but the discussion was limited to things like power and fuel, and the Flanker does have to pay a price for some of its capabilities. The main reason I responded was the statement that the Flanker has more powerful engines–yes it does, but it is still a less powerful fighter than the F-15C under most realistic circumstances. My theme was that things aren’t always what they seem.

Outside of aircraft, the AK-47/AKM’s legendary ruggedness similarly requires a few additional parts over the M16’s direct-impingement system.

Rubbish. The M-16 has lots of little bits to lose or break.

I’m aware of that, but it’s beside the point.

The only thing it lacks over an AK is a piston rod and the piston rod in an AK is attached to the bolt carrier so it isn’t actually an extra piece.

Well, it’s an extra feature, isn’t it? Still not satisfied? OK, forget I mentioned it, then. My other two examples were more to the point in any case.

The Flanker is comparatively weighed down by its internal fuel load, especially since it doesn’t benefit much from carrying it all internally (drag is reduced, although this advantage is not as pronounced with external weapons hanging on it anyway).

And the weapons loadout is not effected by having to carry external tanks?

Of course it is affected, but since we’re talking about the F-15C specifically, I was thinking in terms of air superiority. The standard air-to-air load on the F-15C is eight AAMs, which it can carry regardless of how many external fuel tanks it is carrying. All it takes is a single centerline tank to match or slightly exceed the fuel fraction of the Su-27, leaving the two wing pylons (each capable of carrying a relatively heavy load) free for additional ordnance when required.

Not being able to pull 9 gs just after takeoff is not very important because who pulls 9gs today? High off boresight missiles and BVR missiles don’t require 9g turns.

Be that as it may, the point is that the Su-27 is not more capable than the F-15C in every way. Going strictly by the numbers, the Su-27 seems to be of a very similar level of technology indeed, with the exception of its more refined aerodynamics. The F-15C’s design is leaner and more powerful, while the Su-27’s design gives it some advantages of its own. However, with regard to the subject of external tankage vis-à-vis extra-large internal tankage, it seems that the use of external tankage can actually yield advantages in both performance and range under some circumstances, at the cost of taking up space for ordnance, as you pointed out.

I can easily believe that its engines and aerodynamics give it better fighter-type performance than the F-111

Very generous considering the F-111s fighter capacity is zip.

Well, I guess it just doesn’t pay to be nice. 😉 It’s not as though anyone expects the Su-34 to be a fighter anyway with that type of cockpit, which is not an issue with the Su-30 or F-15E, for example.

If F-15E level payloads are required then a Tu-22M3 makes much more sense.

Sometimes you have to use what you have, and I was just pointing out a relative deficiency (on paper) of the Su-34 system when compared to similar systems. While it has greater range than the Su-30 and better crew comfort for long missions, it doesn’t carry more ordnance. The poster to whom I was responding seemed to want to know whether the Su-34 was simply superior all around to systems like the F-111, and the answer is no, it’s an “in-betweener” with certain relative strengths and weaknesses.

I wouldn’t put my money on the F-15 going against the Su-27 if my life depended upon it.

My comparison was limited to the merits of external fuel and the relative power of the two aircraft. Somebody suggested that the Su-27 is more powerful than the F-15C, but the opposite is actually true in most cases in terms of T/W.

The US Air Force claims the F-15C is in several respects inferior to, or at best equal to, the MiG-29, Su-27, Su-35/37, Rafale, and EF-2000, which are variously superior in acceleration, maneuverability, engine thrust, rate of climb, avionics, firepower, radar signature, or range.

That is a rather vague statement made by an entity that has a strong interest in convincing the Pentagon and Congress to procure a next-generation air dominance fighter in greater numbers, namely the F-22. I happen to agree with them for many reasons that I won’t get into here, even though the F-15C upgraded with AESA and JHMCS would be a formidable platform for quite some time.

Although the F-15C and Su-27P series are similar in many categories, the Su-27 can outperform the F-15C at both long and short ranges.
http://www.fas.org/man/dod-101/sys/ac/f-15.htm

Range 3,450 miles (3,000 nautical miles) ferry range with conformal fuel tanks and three external fuel tanks. 3,100 nm (3,570 miles; 5745 km) ferry range with CFTs and drop tanks
2,400 nm (2,765 miles; 4445 km) with drop tanks
1,000 nm (1,150 mi; 1,853 km) Max Combat Radius
685 nm (790 miles; 1270 km) combat radius
http://www.globalsecurity.org/military/systems/aircraft/f-15-specs.htm
Range: 1,340km combat mission at sea level 3,530 km combat mission at high altitude (800 mi at sea level / 2070 mi at high altitude)

Range 1,500 km combat radius [typical] (Su-27)
1,800 km cruise radius
4,000 km maximum range
http://www.fas.org/nuke/guide/russia/airdef/su-27.htm

So as you can see combat ranges favours the Su-27 and obviously so considering it’s a rather larger ( empty weight differ by 30%) plane with a significantly larger internal fuel carriage ability

We have to be careful with the notion of “combat radius” because these can entail very different mission profiles. The hypothetical scenario I described in my last post favors the F-15C in terms of range and performance when it carries two external tanks, which is typical. If you want the actual numbers I used, here they are:

Start of mission:

Su-27: 16380 kg empty weight, 9400 kg internal fuel, 2×12500 kgf thrust, 0.97 T/W, 0.365 fuel fraction

F-15C: 12700 kg empty weight, 6200 kg internal fuel, 2×1854 kg external fuel, 2×10782 kgf thrust, 0.95 T/W, 0.438 fuel fraction

Fighters meet at the midway point when the F-15C drops the empty tanks:

Su-27: 16380 kg empty weight, 5692 kg internal fuel, 2×12500 kgf thrust, 1.13 T/W, 0.258 fuel fraction

F-15C: 12700 kg empty weight, 6200 kg internal fuel, 2×10782 kgf thrust, 1.14 T/W, 0.328 fuel fraction

Obviously, some very simplistic assumptions are made for this hypothetical scenario, such as equivalent fuel burn rates, but their listed maximum ferry ranges in these configurations are fairly close, with the drag of the F-15C’s external tanks apparently balancing the additional thrust needed for the Su-27’s larger size.

As you can see, at the midway point, raw power is similar but the F-15C’s fuel fraction is better, which shows us the advantage of carrying external tanks; it’s like a less extreme version of having multiple rocket stages. Closer to the F-15C’s base, the Su-27 will have better power but an even worse fuel fraction, of course, and as others have pointed out, the difference in power is mitigated to some degree by the F-15C’s ability to jettison excess fuel quickly. Closer to the Su-27’s base, the F-15C’s power advantage will be greater and its disadvantage in fuel state will be less severe. The key figure above is the F-15C’s superior fuel fraction with external tanks.

Fuel Capacity (F-15A)
internal: 11,600 lb (5,260 kg)
external: 11,895 lb (5,395 kg)
(F-15C)
internal: 13,455 lb (6,105 kg)
external: 9,750 lb (4,425 kg)
http://www.aerospaceweb.org/aircraft/fighter/f15/

The external fuel figure for the F-15C here looks strange–why should it be different from that of the F-15A? To me, it looks about right for two conformal tanks, but I’m talking about two external 610-gallon tanks (at 6.7 lbs/gallon for JP-8).

Maximum internal fuel, kg 9,400 (Su-27)
http://www.sukhoi.org/eng/planes/military/su27sk/lth/

Fuel in four integral tanks: three in the fuselage and one split between each outer wing. Max internal fuel capacity is approximately 11,775 litres (3,110 US gallons or 2,590 Imp gallons), while the normal operational fuel load is 6,600 litres (1,744 US gallons or 1,452 Imp gallons). The higher figure represents an internal auxiliary tank for missions in which manoeuvrability is not deemed important.

Ah, this means that the Su-27 carries around a bunch of space that it supposedly doesn’t use all of the time. Obviously, this is difficult to reconcile with the USAF doctrine of loading tactical aircraft full of fuel for every combat mission (you never know when it might come in handy).

A question that I’ve always had is whether operators of the Su-27 and its many variants ever fill the aircraft with their “normal” internal fuel load–which is little more than half of the maximum capacity–as part of their doctrine. If not, then perhaps the whole notion is just marketing that makes the Su-27’s performance numbers look better in order to increase sales, much like how the USAF keeps trying to make the F-15 look worse so that they can get more F-22s.

There are no provisions for external fuel tanks, except in those versions where it is specifically indicated.

Certainly not the basic Su-27, as far as I’ve ever seen.

So given that it’s obvious which is going to go further and very probably faster….

Neither aircraft are going to go much faster than the other–probably Mach 0.85 or below for most of their missions, at least until they’re preparing to attack. The F-15C with external tanks has a superior fuel fraction, therefore it will generally go farther and/or have better T/W performance at most points during missions.

In long-range encounters, with its superior radar the Su-27 can launch a missile before the F-15C does, so from a purely kinematic standpoint, the Russian fighters outperform the F-15C in the beyond-visual-range fight. The Su-35 phased array radar is superior to the APG-63 Doppler radar in both detection range and tracking capabilities.

This is not something I had intended on getting into, but I doubt that the Su-35’s (probably the Su-30MK variants in the real world) radar is superior to the AESA that equips some (and eventually all) F-15Cs.