Latest fighter aircraft designed trend

[mvsgas]

I was just thinking about all the fighter designs lately.

You look at the MIG 1.44, J-10, Rafale, JAS-39 and Eurofighter Typhoon they all have similar aerodynamic designed ideas. I think they are all modified delta wings right? They all have froward all moving planes or canards. Yet two of the most successful aircraft designers, Lockheed Martin and Sukhoi, choose to go with a different designed ideas. LM with F-35 and F-22 and Sukhoi with SU-35, SU-30 MKI/MKK, SU-34/32.

--I wander why is that?

--What do you guys think is the reasoning behind this designed difference?

LM, I think, choose those designs because of Stealth requirements, What do you think?

There has to be many benefits with a modified delta wing with canards when so many different aircraft manufactures choose this. I was just think what do you guys think.

[Pilotasso]

The trend depends on manufacturer experience. If you look at americans side you see their F-22 and 35's have followed a different aproach (more conventional). Full authority cannards on the european planes and the chinese J-10 are however new. They used to be just fixed vortex generators.

[GGTharos]

Stealth has little to do with it. Ask yourself: What does a delta wing and full authority forward canard give you? ...

Then compare with the design of the F-22, and F-16/F-35 ... I think you'll get your answers then!

[mvsgas]

That is the the thing GG, I'm not sure about the benefits of modified delta + canards. Is it better maneuverability or a compromise between maneuverability, drag, lift and weapons caring area? Is it because of the delta wing performance at hight mach speeds? This is the thing I was wandering. I know I can probably find some info somewhere in the net but it is not as interesting as reading what you guys have to say about it.

[GGTharos]

Delta gives you a lot of lift area, and it has no problem in terms of supersonic flight. You get very low wing loading which means your instantaneous turn rate will be very good, although unfortunately it also serves as an airbrake when you do this.

It also allows you to carry a LOT of weight on your wings.

 

Forward canards potentially give you very good authority in high AoA regimes where the tail could stall out, but I haven't seen any F-18's or MiG-29's worry about that so far.

 

For supersonic cruising performance, LM decided to go with vectored thrust - I don't recall the specifics, but it allows more fuel efficient supersonic flight. It also have a lifting body, so its wing loading is also low - much like an F-15.

 

In the end, it depends on what you want to achieve with your fighter - note that none of the delta wings were really designed for sustained supersonic operations, but I doubt this has much to do with the wing - the F-15 turns into a delta for high speed flight, as does the F-111, tornado, and other aircraft. The straight wing in those aircraft however appears to help maneuverability at low level and speed.

 

Sadly, I can't give you a real answer as I don't know it myself. :)

In the end it's the requirements of the purchasing/ordering nations and experience of the aircraft builders that shape what they think is the best bang for the buck.

 

Personally, I wouldn't want to fly a delta: If you didn't get your kill in one turn, you'd now have to deal with an energy-tactic using bandit pouring down on your tail.

[mvsgas]

Do you think thrust vectoring has to do anything with supersonic cruising?

I'm really asking not trying to be cynical or anything

I think it has more to do with the fact the aircraft had clean aerodynamic configuration (when not carrying external store of course) like a A-5 or a RF-8 which IIRC could get supersonic with less AB/re-heat power that for example a F-4S escorting them because they did not carry any external store and had less drag.

Or it could be because the engine have a lot more power now.

Edit

Or it could be a combination of the two things

Edited August 7, 2008 by mvsgas
adding a thought

[RedTiger]

I'm with you here mvgas. I don't get the European obsession with delta wings. Like GG said, it depends on what the end user wants and what the builder thinks will work best.

 

But for deltas...Western European air forces think triangles are nifty looking? :dontgetit:

 

The delta design stands in sharp contrast to what the two super powers designed at the end of the cold war. The US continues along those lines. You mentioned that vaporware MiG, aren't all the PAK FA concepts drawings very similar to the Raptor?

[GGTharos]

Do you think thrust vectoring has to do anything with supersonic cruising?

 

So sayeth the guys who designed the raptor. I wish I could find the quote for you :(

 

I'm really asking not trying to be cynical or anything

I think it has more to do with the fact the aircraft had clean aerodynamic configuration (when not carrying external store of course) like a A-5 or a RF-8 which IIRC could get supersonic with less AB/re-heat power that for example a F-4S escorting them because they did not carry any external store and had less drag.

Or it could be because the engine have a lot more power now.

 

Both - the F-22 can supercruise, so you know the engines are 'that hot'.

Flying clean naturally does nothing but help out.

 

It is possible that vectored thrust allows you to maintain a certain AoA to fly straight and level at those speeds without requiring elevator deflection or trim - that saves of JUST a little bit of drag (Actually, it's probably huge when supersonic, but what do I know) which adds up majorly over time.

[mvsgas]

I have read some where ( I think it was in CODE ONE magazine web site) that the horizontal stab do generate lift at supersonic speeds (at least on the F-16) I wander if the canards do the same? If I had to guess I figure that they probably do. I also wander if the intake in the F-22 acts as a LEX (leading edge extension) like the ones on the F-18,F-16,MIG-29 or SU-27?

Sure look like they do here:

[GGTharos]

The horizontal stabs always generate lift, but perhaps more so at supersonic speeds - perhaps enough that you'd have to trim them out - in which case TVC might be a cure for just that.

 

I don't know if you know how supersonic airflow works - it's basically a compressed (and no longer compressible) sheet of air, as opposed to the 'fluid' compressible air that we normally think of (ie. subsonic) and its properties change accordingly.

 

For example, you need more deflection of a surface than you need at subsonic speeds to achieve a particular number of g's ... now imagine you're flying at M1+, hauling stick for all you're worth, and suddenly you slow below mach .... oooooops. :D (Modern planes deal with this though by altering your inputs, be it mechanically or through fly by wire).

 

Edit: Here's some answers for ya :D

 

http://en.wikipedia.org/wiki/Delta_wing

Edited August 7, 2008 by GGTharos

[mvsgas]

Well there you have it, "Wiki" to the rescue again :D Cool "GG" thanks. I think delta wings have always made beautiful aircraft.

[mvsgas]

Well, reading around on the web. I guess making a aircraft with modified or delta wings and canards will give you the best compromise (agility, lift, drag, fuel, etc) without using thrust vectoring. I guess thrust vectoring would make an engine way more complex, prone to failures and expensive

[GGTharos]

Thrust vectoring does make things more expensive. One of the reasons the F-22 only has symmetric 2D TV is probably cost, and the fact that vectoring thrust in all sorts of other directions is probably not all -that- useful.

 

On the other hand, a wing different from a delta can provide you with better maneuverability in some flight regimes, which you see demonstrated in just about any modern non-delta aircraft, ie. F-16/18/15, Su-27/35, MiG-29/35 etc.

 

Notice how the superpower airforces have actually transitioned AWAY from delta wing designs - they all had some experience with delta wings and a number of delta wing fighters in the past.

 

In addition, even the F-16 was tested with a proposed delta wing, and as you can see, no delta winged aircraft are being accepted in so far!

[tflash]

Very interesting in how things evolved towards today's Typhoon and Rafale on the one hand and F-22/F-35 on the other is the case of the X-31 high manoevrability demonstrator: http://www.nasa.gov/centers/dryden/news/FactSheets/FS-009-DFRC.html

 

It is difficult to miss the similarities with the Typhoon design (and also IAI Lavy and Chinese J-10).

 

In X-31, Canard/Delta , FBW and Thrust vectoring where combined to achieve Supermanoevrability and STOL. I guess participating German companies (now part of EADS) liked the first two solutions better than the involved American companies and DARPA.

 

Dassault was very early on into Canard/Delta, they are not that big that they could afford experimenting with radically new designs. Canards solved a lot of the Delta's limitations; FBW added even more (you can do some airflow magic by computer-controlled canards).

 

I suppose the F-15 was such a sound design (it still even transpires in F-22) that US found it a way better solution than the quite complex and still limited canard/delta config). The F-15's wings seems so simple, but it must be a damned good design.

[Groove]

X-31:

 

 

I have more if anyone is interested :D

[tflash]

Wow, great picture! Which museum?

[Pilotasso]

 

Notice how the superpower airforces have actually transitioned AWAY from delta wing designs - they all had some experience with delta wings and a number of delta wing fighters in the past.

 

In addition, even the F-16 was tested with a proposed delta wing, and as you can see, no delta winged aircraft are being accepted in so far!

 

It was underpowered for such a big wing area. Overkill realy. Its whole design was based on conventional wing and horiz stabs. The delta was an experimental strappon, and it failed to atract orders.

 

 

Eurofighter or Rafale on the other hand lack no power for tight turns. Gripen has T/W ratio under 1:1 yet it seems to be very agile, with one of the most efficient aerodynamic profiles it gives the F-16 a run for its money.

 

Canard deltas being aerodynamic brakes is a myth realy. It comes a bit from Mirage III material wich was always a benchmark in compromises for the straight delta wing design but no longer holds true.

 

Superpowers ditching the deltas? The interpretation I got is that these countries chosen conventional designs for money and less development risks instead, not because deltas were inferior. For these reasons historicaly any modern jet designed in the US or modern Russia with more elaborated wing configurations outside established expertise were always ditched independently of being deltas or not (included pelican tails).

Edited August 7, 2008 by Pilotasso

[Groove]

Wow, great picture! Which museum?

 

German Museum Munich.

 

http://www.deutsches-museum.de/en/flugwerft/information/

[RedTiger]

 

I suppose the F-15 was such a sound design (it still even transpires in F-22) that US found it a way better solution than the quite complex and still limited canard/delta config). The F-15's wings seems so simple, but it must be a damned good design.

 

I dug this up about the F-15's wing design:

 

"McDonnell Douglas had spent more than 23,000 hours wind tunnel testing over 100 different wing/body combination before it felt it had the bet wing shape for what it now termed its 199-B design. Considerable time was spent optimizing the airfoil for minimum drag in both low- and high-altitude flight regimes. What resulted was a sophisticated, highly cambered wing shape devoid of any high-lift devices as seen on the slatted F-4E, and one which conferred excellent maneuverability, even under high g-loading. Because the Eagle had only a simple flap and aileron on each wing, assembly and maintenance were straightforward. Less obvious, though, was that McAir engineers had built a three-spar wing with redundant load paths that would allow the Eagle to sustain significant battle damage to its wing without losing the capacity for control throughout the basic maneuvering necessary to limp home and land." - F-15: Eagle Engaged

 

In another book I have, it shows some of the wing/body combination. Some are fixed, some are variable swept, but some of them are indeed very delta-like, however none are a true delta. They all have all-moving tails, kinda like the MiG-21.

[Alfa]

Very interesting in how things evolved towards today's Typhoon and Rafale on the one hand and F-22/F-35 on the other is the case of the X-31 high manoevrability demonstrator: http://www.nasa.gov/centers/dryden/news/FactSheets/FS-009-DFRC.html

 

It is difficult to miss the similarities with the Typhoon design (and also IAI Lavy and Chinese J-10).

 

In X-31, Canard/Delta , FBW and Thrust vectoring where combined to achieve Supermanoevrability and STOL. I guess participating German companies (now part of EADS) liked the first two solutions better than the involved American companies and DARPA.

 

Dassault was very early on into Canard/Delta, they are not that big that they could afford experimenting with radically new designs. Canards solved a lot of the Delta's limitations; FBW added even more (you can do some airflow magic by computer-controlled canards).

 

I cannot add anything useful to the discussion regarding the benefits of Delta vs "conventional" wing design, but I think the point about designers tending to stick to what they have the most experience with might hold true - e.g. after multiple delta wing Mirage variants, Dassault did design a version with conventional wing configuration(Mirage F1), yet reverted back to Delta wings with the more recent versions(Mirage 2000) and again with the Rafale.

[GGTharos]

I think you got the wrong interpretation. It seems that deltas were easier to design - at least, going by the wiki.

 

Superpowers ditching the deltas? The interpretation I got is that these countries chosen conventional designs for money and less development risks instead, not because deltas were inferior. For these reasons historicaly any modern jet designed in the US or modern Russia with more elaborated wing configurations outside established expertise were always ditched independently of being deltas or not (included pelican tails).

[mikoyan]

Deltas are good design for a small fighter, they allow you to carry more fuel and give you lots of area to lift your airplane, they also give you great instantaneous turn performance (not sustained) that is true for earlier and some modern delta jets. If you see a mirage-2000 demo the pilots do a lot of instantaneous turns but not a lot of sustained turns; still it is very impressive haw fast the mirage can point its nose. Deltas are easy to construct too, and give the airplane a stronger structure. The mirage 4000 was a bigger twin engine version of the mirage 2000, it had canards too. For some reason the airplane didn't look as agile as its smaller brother, maybe that is one of the reasons for ditching the design?

The f-22 seems to have a delta wing too, what it is most interesting about it is how the ailerons work on this jet, wen the airplane is puling up the ailerons also pull up, as the slats go down, Maybe this is is to increase the was out and to reduce drag?

[mvsgas]

I wander if on the F-22 the ailerons go up or they look like that because the flaps go down

[mikoyan]

I was able to see an f-22 on static display here in GA and I was puzzled by the big washout of the wing tips and how tick wingtip was.

[Pilotasso]

I think you got the wrong interpretation. It seems that deltas were easier to design - at least, going by the wiki.

 

That is a straight delta design, like the one on the mirage III. It isnt used for a while. ;)