EXACTLY! The “problem” is far to often it has been found that MORE range is needed more often than not than was ‘specified/designed’. So the NEED to carry external tanks just to get the range needed most of the time. External tanks add MUCH more drag than a equal amount of (increased) internal fuel & they take up hardpoints that are no longer available for weapons.

If we stick to the Suchoi 27 vs F-15 example (the other comparable pair would be the F-16 vs MiG-29, but here the F-16 wins even without external tanks), we’ll see that both designs can take 8 missiles. The Suchoi actually can take up to 10, but necessity of 10 missiles is somehow dubious. So, 8 AAM for both, the F-15 actually can’t take more than that, even without any external fuel (so no external store is sacrificed for a2a missions).
The tanks add drag that should somehow be equal to the drag saved by semi-recessed missiles, maybe some drag remains. But when combat is on the doorstep, the F-15 drops its tanks and suddenly comes out with less weight, less drag and better performance than the Suchoi 27, which has to carry its empty fuselage volume all the way through combat and back home.

Honestly, if I want to have maximum combat performance, does it make sense to carry the volume needed for taxi and warm-up fuel during combat? Wouldn’t it make more sense to have a cumbersome external storage, that gives me that fuel, eats into my performance when I don’t really need it and which I drop when I need the performance?
Answer: yes, it does.
Prove: see all designs before and since the Suchoi 27 (except stealthy designs).

Again, internal fuel is the best BY FAR but conformal tanks are WAY better than external ‘drop tanks’ & in fact generate comparatively little performance penalty [more than the equivalent internal fuel but less than external ‘drop tanks’].

Conformal tanks are favorite for pure fighter-bombers, as trans- and supersonic performance isn’t needed or remains as secondary dash capability (with a2g weapons dropped, an F-15E does make it over the barrier even with CFTs). With a2g weapons it remains below M0.9 anyways, so extra tanks don’t hurt that much. A six-pack of Mk82 Snakeeye adds drag in preposterous dimensions, a 600gal tank looks like school boy compared to that.

BINGO! The F-15A NEEDS 2 external tanks (1220 gal) which add ~10,000 lbs (weight of fuel & tanks combined) in order to match the range or radius of the Su-27.

But the F-15A achieves in the end
– same radius
– with same weapons
– with same combat performance (approx., we don’t need to count beans)
with
– 3.5t less OEW
– 5000lbs (appr.) less installed reference thrust
but still retains (at combat, means tanks dropped)
– a better fuel ratio in combat (translates into more endurance, more burner time)!
– lower wing loading in combat
– has better TWR (at least taking zero-zero conditions, but both aircraft use quite comparable engine type and installation, so able to compare)

Now, for one combat flight, there will be 50 non-combat flights, where no tanks is dropped, no missile expended or carried at all.

Which one is the smarter design?

Answer by the designers of all supersonic aircraft before and since anywhere in the world (except stealthy designs): the F-15.
Answer by the designers of the Su-35: the F-15.

what about:
Romania nothing in ’09
Bulgaria nothing in ’09
Kroatia nothing in ’09
Greece nothing in ’09
Canada nothing in ’09
Danmark
Japan nothing in ’09
Saudi second order nothing in ’09.

Anyone more in the loops for buying fighters?

Bulgaria is technically bankrupt, so will be Greece and Romania in a few years to come. Japan has more federal dept than the USA (not relative, absolute!).

Swiss competition: Rafale, Typhoon, Gripen
Indian MRCA: Rafale, Typhoon, F-16I, F-18E, MiG-35, Gripen
Brazil FX: Rafale, Gripen, F-18
Libya (they didn’t sign anything final with Russia yet): Flanker, Rafale
Nederlands: F-35, Gripen

Swiss: Typhoon
India: F-16 with big workshare, or nothing in ’09
Brazil: Rafale with a box of red wine, or nothing in ’09.
Libya: Nothing in ’09 as long as barrel below 70 bucks
Netherlands: F-35, or nothing in ’09, still a few years to go

Remember that most countries feeling the economy downturn even harder as the West.

Anyway , my last comment about that, i wanted a more detailed explanation from martinez about these tables, the tendency between speed/heigh, if external tanks are used (or can be used) at 13000 mts, the relative consume of fuel in the different configurations, nobody has made these comments,that is what im looking for in this thread, you can keep your techno-babbling for yourself

At least I can do techno-babbling, and don’t need just to pretend I know what I am talking about.
Post 123 is advised.
http://forum.keypublishing.co.uk/showpost.php?p=1342812&postcount=123
Sorry, techno-stuff again, if necessary I can dump it down a bit.

After some serious searching I found another interesting source, once again Russian. It shows specific excess power at NZ=3 (at has various other charts but I found this one most interesting). Anyways, it shows the F-15 on par with the Su-27. Don’t know how accurate the sources are, and which exactly are the assumptions, but at least they prove my point: both play in the same league, not worth arguing about.

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You know, nominal values (the M2.5 for example) are not always the practical and real ones, stop being an annoying brat Sens, with your techno babbling please and leave aside for a moment your trademarked “Your lack of basic knowledge aside” phrase..

But he is essentially right.
Top speed aside, both will hit the stops at around M2 in a pure missile configuration.

That is not the whole story i dont care if you know that, but, for example g-envelopment graphics help a bit, also the 27 has demostrated a cruiser speed of M1.5 in a circuit of 1000 kms -with 1000 kg of load, rather low, but it was a circuit anyway-, the f-15 simply was not designed for that, there are a lot more factors like acceleration at heigh, output thrust at heigh/speed, etc, claiming that both planes are the same just by nominal values is not the real deal

Rubbish. In 1G flight there is no noticeable difference. Where should it come from? The Suchoi 27 has similar wetted area, similar intakes and in supersonic the AL-31 are even harder gas guzzler as the F100s (partly compensated by relaxed stability on the Su-27).

The su-27 use true 4th gen aerodynamics (like the F-16 -blended wing, lerx, and new aerodynamic topology), while the f-15 ones are more 3.5 generation

That’s good news for the Su-27 and it will achieve slightly better sustained turn rates by that. But wing loading is higher, so the advantage is partly canceled. For considerations about range it is without importance, and combat performance is similar most of the time, the “true 4th gen aerodynamics” don’t change night into day.

Anyway , about the big airline drop tanks, i think there are some structural problems related, when one try to reach an acceptable volume/weight rate for such big things, dont remember well, but i think ET’s were designed for the B-52?

As I said, for a mission of carrying stuff from A to B at a constant Mach number, no-one would consider external tanks. The B-52 was designed in the 1940s and 1950s, don’t take it as representative aircraft.

martinez, can you translate the pictures that you have posted? i dont understand russian either, and i think the tables show a relation between heigh and fuel consume, or im wrong?,please at least post an explanation..

Actually, I already read out the useful numbers and analyzed them, without any Russian knowledge, whatsoever. Come on, it ain’t that difficult. Don’t you consider yourself an expert?

You are wrong there, the su-27 is more a road runner with dogfighting capacity, the f-15 is a subsonic figther with a limited supersonic capacity, both are different beasts.

I am not exactly sure what you are basing your comments on.
Have played lot’s of arcade simulations?
But basically, sorry, you have not really a clue about flight performance, especially the practical side (forget top speed, peak turn rate and other record attempts).

And as it was said before, this is not the case for Su-27. The ammount of fuel that Su-27 carry is result from the blended wing/body design.

So, you tell me they designed the aircraft and – surprise – had extra volume left? Why did they make it so large in the first place?
Given that the engine was purpose-built (means the airframe scales the engine and not the other way round like the F-16,F-104 or F-4), they could easily have reduced the weight by using a single drop tanks, semi-recessing the larger missiles and arriving at lower weights.
But note that both designs (Su-27, MiG-29) of that time suffer from overweight, if pitched against similarly performing aircraft of the West. Reason is in my eyes not any inability of the involved designers, but (like with many Soviet-time designs) strange specifications.

A380 ambition was just the thing being big.
787 is a whole new ball game. So is A350. Plastic wing skins and main spars are a complete and utter nightmare to make and assemble. At least Airbus will learn by the mistakes on A400 and hopefully not put them into A350.
The industry was not and still isn’t ready for the CFR Plastic main Wing components. They are OK an a fighter or a stiff winged Bomber like B2 but the introduction of a wing that flexes, generally has a longer flight duration, carries talking baggage that doesn’t have a “Mummy!” handle etc. etc. is bringing assembly nightmares – in cost and difficulty.
Boeing is presently going through the same pain the A400 did 18 months ago. And it still isn’t resolved.

It I recall correctly the B787 center wing box is 75% conventional*. That it approximate the same percentage of “awesomeness” as the A380 had in its wing box. Spars are also made of metals. Composites are no Über-stuff, they make sense to apply in some areas. A 100% (of primary structure) composite aircraft for large high-cycle flexible aircraft is indeed rubbish. The intense hype around the B787 sometimes smokescreens the careful balance Boeing did between “advanced materials” and proven solution.
The problems are only partly due to the extreme revolutionary design (which it isn’t) of the B787, but are generally caused by the inability of the involved companies of delivering the stuff in time and date and quality. Like with the A380.

A reasoning like: “the B787 is so revolutionary, therefore it sees delays, therefore it is very revolutionary” is also rubbish. The A380 had a number of key innovations, funnily enough, none of these caused major concerns (at least none that led to major delays). These came from areas that were in no ways on the edge of technology, although they were big engineering challenges (but no scientific breakthroughs or “indsutry’s first”). The B787 “disaster” is one of management, it is what happens when you try to make it as the guys from Price Waterhouse Cooper’s tell you. Who needs 20 years of engineering experience when he has an MBA from a known university?

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*: before anybody starts feeling offended: conventional is nothing negative, actually, it is something good and positive. “Conventional” means proven, tested and understood. Any “unconventional” solution must be regarded with great care by any aviation engineer at first, and should generally be applied to aircraft with “Mummy!” handle.