What module next?

Maybe by flying like a "brick" the OP doesn't mean how the thing turns, but how it "feels". I actually share his sentiment somewhat. Let me illustrate through a prop example. The F6F can turn tighter and faster then a F4U, especially at lower air speeds. However, despite not turning as well, the Corsair (as long as you keep it fast) somehow feels "livelier". Not sure, if i am describing it well. I think it's not just the responsiveness of the controls but also about their "softness" ???? I better stop, before i start writing poetry :P

Suffice to say, imagine if the Su-27 and F-15 were exactly the way they are now, but their turning performance was the same or reversed. It's that "feel" that makes them fly differently.

I think the OP probably means that F-15 needs a bit more care about AoA when pulling the stick too far for turns, and this leads to it feeling a bit trucky after losing some speed.

Eagle is one of the top 3 in agility among current jet fighters (well the non-SFM ones anyway), and certainly the one with best thrust / climb / acceleration, but I guess when it comes to turns it doesn't feel as carefree as the Mirage or Su-27.

Like others mentioned, the Eagle has plenty control authority, and maybe that authority leads us to bleed energy really quick and get the aircraft out of its sweet-zone rather easily, hence leading to a feeling of sluggish handling, even though when flown correctly it is a beast.

No I mean it flies like a brick, I know how to fly fellas. I use Cobra mode on the Su27 all the time. To me the Su27 has more of a smooth feel then the F15 which is why I prefer the Su27. I do not mean that the F15 cannot maneuver, it's just not as graceful imo.

No I mean it flies like a brick, I know how to fly fellas. I use Cobra mode on the Su27 all the time. To me the Su27 has more of a smooth feel then the F15 which is why I prefer the Su27. I do not mean that the F15 cannot maneuver, it's just not as graceful imo.

Comparable to flying a brick. Not sure I agree.. a flying brick to me would be an F4.. With enough power even a brick will fly I.e. F4/orbiter. While Yes the F15c is an extremely stable aircraft it surely isn't deplorable in regards to agility. The issue that you're facing is the lack of instability that the su27 has. The "aft" CG that the su27 has allows a quick response in Nose pitch coupled with the LEX and large control surfaces allows for response in the upper AOA.

Take away the "band aided" fixes to the SU27s wing design away and you will then have a flying brick.

The thing with the f15 is that the wing design is pretty close to perfect.

If you look at the F22 you will notice is is pretty close to the same as the f15 but with LEX. Both are cropped delta. I would not be surprised if the original design phase of the wing for the f22 wasn't borrowed from the f15. [should state 2nd design after the original concept was trashed by Lockheed] What I'm trying to get at is that the su27 would be a dog with out an aft cg and LEX. If you add the same features to the f15 then you essentially have an f22 which can perform the same maneuvers and more then what the Su27 is capable of doing. and YES the f22 can do the cobra with out the use of TVC

but back to on track I can see what you're getting at in terms of how it flys. I just can't see explaining it as a "flying brick" more to me I would say it flys like forward hockey player. Vs the su27 that is a defensemen with figure skates ON! one wrong move and you've got broken ankles err Wings/vertstabs

 

but back to on track I can see what you're getting at in terms of how it flys. I just can't see explaining it as a "flying brick" more to me I would say it flys like forward hockey player. Vs the su27 that is a defensemen with figure skates ON! one wrong move and you've got broken ankles err Wings/vertstabs

Yeah, grace would have been a better choice. And that said I can get some smooth turns on the F15!

The SU-27 is a great airshow plane. Too bad they didn't put more effort into the radar and missiles.

The SU-27 is a great airshow plane. Too bad they didn't put more effort into the radar and missiles.

What's wrong with the radar?

What's wrong with the radar?

It didn't quite compete with this, perhaps?

Okay okay that's IRL not in-game, whatever. :P

The thing with the f15 is that the wing design is pretty close to perfect.

If you look at the F22 you will notice is is pretty close to the same as the f15 but with LEX. Both are cropped delta. I would not be surprised if the original design phase of the wing for the f22 wasn't borrowed from the f15. [should state 2nd design after the original concept was trashed by Lockheed]

Oh really?

What I'm trying to get at is that the su27 would be a dog with out an aft cg and LEX. If you add the same features to the f15 then you essentially have an f22 which can perform the same maneuvers and more then what the Su27 is capable of doing. and YES the f22 can do the cobra with out the use of TVC

That's like saying an F-15 would suck at BVR if it didn't have a radar or an F-18 would suck at carrier landings without a tail-hook. Then adding these things to whatever we like and claiming it is now a superior BVR carrier based fighter. - Completely baseless speculation.

Give him a break, after all haters gotta hate.

What's wrong with the radar?

Nothing until the F-15 shows up.

Oh really?

 

 

 

 

That's like saying an F-15 would suck at BVR if it didn't have a radar or an F-18 would suck at carrier landings without a tail-hook. Then adding these things to whatever we like and claiming it is now a superior BVR carrier based fighter. - Completely baseless speculation.

Give him a break, after all haters gotta hate.

Both wings on the f15 and f22 are cropped delta wings with altered dimensions for stealth and area. For the most part the airfoil design I.e. cross section is relatively the same.

As far as my saying that the SU sucks with out the LEX is simple. The wing/airfoil design is inferior to that of the F15. This has nothing to do with fanboyism. The Russians were unable to manufacture a wing/airfoil that is comparable or onpar with that of the f15 wing/airfoil. [At the time of the su27 design inception either due to a cost point or due to limitations in their production environment] Thus to compensate they had to include LEX.. If you were to re-design the f15 wings leading edge[not dimensions or air foil design] to allow adding Leading edge flaps and altering CG by changing what INT fuel tank is used first you will then out maneuver the su27 in all aspects of flight. Before you comment about CG and fuel. The Su27 must burn through its forward tanks to get an aft CG allowing the cobra maneuver.

Now as far as your anology of removing a tail hook or radar does not have bearing in how this conversation was going.

As far as my saying that the SU sucks with out the LEX is simple. The wing/airfoil design is inferior to that of the F15. This has nothing to do with fanboyism. The Russians were unable to manufacture a wing/airfoil that is comparable or onpar with that of the f15 wing/airfoil. [At the time of the su27 design inception either due to a cost point or due to limitations in their production environment] Thus to compensate they had to include LEX.

Comparisons aside, this is factually wrong. TsAGI deliberately included the leading edge wing root extension as the vortices they generate nearly doubles the lift generated by the wings at high AOA. This wasn't to compensate for a poor wing design, it was included simply to add lift under high AOA conditions. The LERX on the Su-27 wing is a much larger version of the idea that was first flown on our very own F-5.

Whether or not the wing developed for the Su-27 and MiG-29 is superior or inferior to any western designs is irrelevant to the fact that the LERX were deliberately added not to compensate for an otherwise poor wing design but to provide lift at high AOA, a condition that the designers knew the aircraft in question would experience.

Comparisons aside, this is factually wrong. TsAGI deliberately included the leading edge wing root extension as the vortices they generate nearly doubles the lift generated by the wings at high AOA. This wasn't to compensate for a poor wing design, it was included simply to add lift under high AOA conditions. The LERX on the Su-27 wing is a much larger version of the idea that was first flown on our very own F-5.

 

Whether or not the wing developed for the Su-27 and MiG-29 is superior or inferior to any western designs is irrelevant to the fact that the LERX were deliberately added not to compensate for an otherwise poor wing design but to provide lift at high AOA, a condition that the designers knew the aircraft in question would experience.

I distinctly remember reading an article or maybe a documentary in regards that during the design of the su27 they tried to roughly copy the wing design of the f15 and was unable to do it.. Not sure if that was due to cost or due to the inability to actually manufacture it. There was also mention in that article about the need for lex to give the chosen wing design to match or out perform the f15.

I'm sorry I do not have a link. as its been a few years since I seen/read it.

Given your statement how is that not in the same confines of what I said before? Could what you say not be considered that the extra lift is needed in high AOA due to wing design and to accomplish this LEX is needed other wise it would not be able to perform adequate enough when compared to the f15 wing? The su27 was developed specifically to go up against the f15

Just the same I read somewhere also about the f15 wasn't given LEX for the reason they concluded the wing design was great and the cost adding lex wasn't justifiable. Wish I still had the links/articles for that.

Now, let it be known I never said the su27 wing design was poor. I just said it was inferior to the design of the f15. The only "Poor design" IMHO of the SU27 is that gawd awful color they chose for the cockpit & the lack of using flush mounted rivets. Does anyone have any calculated numbers of the reduction of parasitic drag if the rivets were flush? I've always been curios about that.

Again I still stand behind my statement in that by removing LEX on the su or adding lex on the f15 & a relative CG between them will result in the f15 having the edge in all aspects of the flight envelope including HAOA.

I think I read somewhere or maybe it was in a documentary I watched while browsing on my phone sometime that said people spout alot of rubbish online:thumbup:

The LERX is to provide extra lift at high AOA. Its not to "compensate" for a deliberate poor wing design.

As far as my saying that the SU sucks with out the LEX is simple. The wing/airfoil design is inferior to that of the F15. This has nothing to do with fanboyism. The Russians were unable to manufacture a wing/airfoil that is comparable or onpar with that of the f15 wing/airfoil. [At the time of the su27 design inception either due to a cost point or due to limitations in their production environment] Thus to compensate they had to include LEX.. If you were to re-design the f15 wings leading edge[not dimensions or air foil design] to allow adding Leading edge flaps and altering CG by changing what INT fuel tank is used first you will then out maneuver the su27 in all aspects of flight. Before you comment about CG and fuel. The Su27 must burn through its forward tanks to get an aft CG allowing the cobra maneuver.

 

Now as far as your anology of removing a tail hook or radar does not have bearing in how this conversation was going.

This would be a more plausible theory if the Su-27 resembled a fuselage and seperate wing with LERX tacked on in the middle ala F-5. But it doesn't. It is a blended wing fuselage design with airfoil sections used throughout the airframe akin to F-16 in order to achieve a lifting body design which would allow for high lift retaining the low drag required for Mach 2 speeds.

Is the airfoil cross section of the F-15 wing superior to that of the Su-27 (ignoring the slats) perhaps, perhaps not. I'm not qualified to interpret that level of wind tunnel and flight test data.

Maybe not fanboyism but the notion that Sukhoi had to band-aid on LERX because they couldn't (and still can't as this design, like the F-15, is still in production with the changes limited to under the skin) design a proper wing sounds a lot like the American superiority complex to me.

Think of my analogy this way then, sticking canards onto a Mirage 2000 won't turn it into a Rafale.

I think I read somewhere or maybe it was in a documentary I watched while browsing on my phone sometime that said people spout alot of rubbish online:thumbup:

 

The LERX is to provide extra lift at high AOA. Its not to "compensate" for a deliberate poor wing design.

I don't keep a record of what I've read on line or watched online. It is a fact the su27 was designed to compete against the f15. It's also known that the Russians didn't have the technology advancements or the concern to spend top dollar in their designs. Hense the lack of flush rivoting. While I could be wrong but This is what I remember when I read/watched an article/documentary about the su27 mentioning the inability to duplicate the wing of the f15. It's not exactly outside of the relm of possibility that the Russians couldn't do or couldn't afford[justify] to replicate the wing of the f15 during the time period it was designed in.

as far as you're reiteration of the LERX to providing extra lift at high AOA is redundant I have not disputed that fact. The question that begs to be answered is with out them and the slats, could the Su27 achieve the same control over the same AOA envelope as the f15 wing? If it cant then they were needed to meet or exceed the design of the f15. Which is how I perceived the article/documentary I read/watched.

While what I said in my first port wasn't exactly meant in the context of the way I delivered it, it was in concept how the OP was referring to how things handled.

Now as I said in my last post I NEVER said the design was POOR I said inferior to the f15. This does not mean anything else. It means what I said. it is less, lower, quality/grade as compared directly to another object. Since I was comparing it directly to the f15 and did not generalize the wing as a whole to all other wings it was not a statement of overall quality.

OP - what did you go for in the end?

This would be a more plausible theory if the Su-27 resembled a fuselage and seperate wing with LERX tacked on in the middle ala F-5. But it doesn't. It is a blended wing fuselage design with airfoil sections used throughout the airframe akin to F-16 in order to achieve a lifting body design which would allow for high lift retaining the low drag required for Mach 2 speeds.

 

 

Is the airfoil cross section of the F-15 wing superior to that of the Su-27 (ignoring the slats) perhaps, perhaps not. I'm not qualified to interpret that level of wind tunnel and flight test data.

 

Maybe not fanboyism but the notion that Sukhoi had to band-aid on LERX because they couldn't (and still can't as this design, like the F-15, is still in production with the changes limited to under the skin) design a proper wing sounds a lot like the American superiority complex to me.

 

Think of my analogy this way then, sticking canards onto a Mirage 2000 won't turn it into a Rafale.

Might help if the included picture was that of the production model SU

Let me help on that

While it is a lifting body design, so is the f15.. I'm not quite sure it's as blended as you make it out to.. How ever I do agree to some extent. Same thing as so you could claim is the f15 all though less distinct to the that of the su27 and A LOT less then that of the mig29 IMHO

your analogy on the m2000 to the raphale is a bit outside of what I'm discussing.. It's hard to argue the point but at the same time since they are made by the same company and not meant to counter the latter it is a bit ambiguous.

The bottom line is this. The su27 was designed to go up against the f15. It is in my personal opinion from what I've read that in order accomplish this LERX/slats were needed.

The Sukhoi design, which was altered progressively to reflect Soviet awareness of the F-15's specifications

Might help if the included picture was that of a su27 instead of a mig

That is the prototype for the Su-27, not a MiG. Google Sukhoi T-10.

That is the prototype for the Su-27, not a MiG. Google Sukhoi T-10.

Thanks for that.. The image didn't look right for a SU so I went off of the rear empennagewhich looks identical to the Mig29

My understanding is the LERX's were not a band-aid, they were present from the initial concept. The LERX required many hours of wind tunnel testing to perfect a shape that generated lift and also enough pitch downforce at positive AoA due to the aft CG. IMO the su-27, in addition to being an answer to the F-15, was the product of concepts deemed cutting edge at the time and were actively being developed in the west.

The development took a very, very long time. The T-10 design was a failure and required a complete rework known as the T-10S which added the leading edge flaps and flaperons. Still, multiple prototypes were destroyed or damaged from in flight break up due to nature of static instability and the heavy, complex wings it required. This required several further iterations to correct.

I don't think it's as black and white as one airfoil being superior to another. I think the su-27 was obviously more difficult to make air-worthy. No F-15 prototypes were lost in development but that doesn't make its airfoil superior, only more predictable.

Might help if the included picture was that of the production model SU

 

Intentional. That is the T-10 prototype, it was to illustrate the blended design better and to show it was a part of the initial design.

I'll give you this, the T-10 had deficiencies that showed it would be inferior to F-15, namely vibrations and poor stability at high AOA, the fix for this was to clip the wingtips and move the fins out to the edge of the fuselage and extend them into ventral fins under the engine nacelles.

At the same time the wing leading and trailing edges were straightened to accommodate slats and flaperons.

Ok yeah that analogy is a bit vague, what I'm getting at is you can't have a Su-27 without LERX, it is such an integral part of the design that the other changes would make it a different plane altogether.

NASA did build some pretty sweet F-15s souped up with canards and TVC among other features, HIDEC and ACTIVE. These were able to demonstrate some impressive AOA prowess, but is difficult to judge if the same things could be applied to a combat capable F-15.

 

Take away the "band aided" fixes to the SU27s wing design away and you will then have a flying brick.

 

The thing with the f15 is that the wing design is pretty close to perfect.

The F-15 has a "perfect" wing? Interesting. The following exercise should prove interesting then. Which of the following planes has the "best" wing? The tables are CL, CD and CL/CD respectively. The blue, the red or the green?

EDIT: just to make things less biased. All the planes here are US made, they are fighters of comparable generation and they employ no lift aids (no flaps or slats).

Are you gonna tell us what fighters you're talking about or is that not dramatic enough?