Why doesn't the USAF uses ay aircraft with delta wings?

While other countries like France have developed their military planes almost exclusively on delta wings, the US has had very few delta planes (Douglas F4 Skyray, Convair F-106, Convair B-58, F-16XL), none flying in the last 30 years or so (the F-16XL lost to the F-15E).

Why is that?
Does it obey a design philosophy or just a taste on aircraft?

Thanks

Okies, I don’t know the answer, but I have some theories (opinions) and one of them may seem like American arrogance, but I am American so there you go.

I assume that the US is further along in aircraft research than other competing nations. Only because we spend so much cash on the tech, and we all must admit it shows in the aircraft as well.

If this is the case, it’s not too much of a stretch to assume that delta wings have shortcomings that don’t lend themselves to more advanced aircraft. What they are I have no idea, but the logic is sound.

Let’s look a little deeper. Delta wings provide a great deal of lift while remaining stable at mach speeds. That’s an advantage, but what has the US found that makes that a lesser advantage over non delta shaped wings?

I think I may know a possible answer. Airborne refueling. The USA has the ability to refuel pretty much at will anywhere in the world. So it does not need huge delta wings in order to create more lift for hauling more fuel. The USA can keep its wings better designed for speed and maneuverability. Its not that other nations don’t use airborne refueling, but we can make a strong argument that the USA has more refueling ability than most, and some nations do in fact not have the ability. If they want range, they need to carry it with them. And the delta shaped wing is better suited for it.

So…If you can refuel at will, why design your plane for handling more fuel? And conversely, if you cannot refuel at will, you need to sacrifice performance to a degree and carry enough fuel with you. And the delta wing can provide that.

I know it’s outside the box thinking, but I bet the truth is close.

We can assume it’s not a straight up performance decision, as the USA has tried and tested every wing shape out there. So there must be a very good reason that it has nothing to do with direct performance vs. performance


[edit on 13-3-2006 by skippytjc]

The USAF has used delta wing aircraft, notably the Delta Dagger and Delta Dart interceptors. It has also seriously considered purchasing delta fighters such as the F-16XL (which lost to the F-15E Strike Eagle) and X-32 JFS proposal (though the proposal was changed to a conventionally tailed design due to spec changes but only ever flew as a delta).

Originally posted by planeman
The USAF has used delta wing aircraft, notably the Delta Dagger and Delta Dart interceptors. It has also seriously considered purchasing delta fighters such as the F-16XL (which lost to the F-15E Strike Eagle) and X-32 JFS proposal (though the proposal was changed to a conventionally tailed design due to spec changes but only ever flew as a delta).

I thought the poster was asking why we dont currently use them if other nations are using them currently. The US has a history that includes delta aircraft, but dont use them at all now where as other nations are developing new tech that uses them. Why?

I am not aware of ANY pure delta designs currently under serious development by any nation for combat aircraft. The closest would be the tailess diamond designs seen in US UCAV and to a lesser extent some British UAV research.

The Mirage 2000 is not a 'pure' delta, it is an compound-delta design with small fixed canards forward of the wing leading edge. Similarly designs such as the Saab Gripen, Eurofighter Typhoon, Dassault Rafael and J-10 are all canard fighters without 'pure' delta main wings.

If any country is developing delta wings, please let me know.
Cheers,

They do ?
Convair F106 Delta Dart ?
North American XB-70 Valkyrie ?
Lockheed SR-71 Blackbird ?
Oh yes & the ever so secret ones that are not yet public.

planeman,
May I say the LCA ?

Delta wings need a much higher landing speed than either fixed non delta or variable geo wings. Also, the actual angle of the plane coming in to land has to be alot more nose up than either of the others.

If you have ever looked at a mirage lll series coming into land, its nose attitude looks like it should be taking off! Theres also an issue about lift at take off and the forces of rotation being detrimental - Ill dig all the links but im pretty sure that for fighter aircraft a delta is not a good idea.

aerodyn.org...
A scientific look at delta wings.

en.wikipedia.org...

Heres a good overview. Basically its all about the energy loss in a turn whilst dog fighting.

[edit on 13/3/06 by MadGreebo]

Originally posted by echoblade
planeman,
May I say the LCA ?

You may! Good one. Mind you that is another modified delta type wing with a dual angle leading edge.

People are not really being very clear on what is/isn't a delta wing.

The F16's wing can be described as "delta".

Other recent US "delta" designs:
external image





[edit on 13-3-2006 by planeman]

Mod Edit: Image Size – Please Review This Link.

[edit on 13/3/2006 by Mirthful Me]

Aww planeman, I was all poised to leap in and point out that the F-16 uses a delta wing then I read your last reply

Also the SR-71 was a delta so I don't know how they are less useful on advanced designs? Come to think of it isn't Aurora supposed to be deltoid?

[edit on 13-3-2006 by waynos]

The SR-71 used a delta wing, but performance wasn't really its strong point. Somebody earlier had a link that pointed out how much energy is lost in turning. The delta wing seems a little less useful only in the more advanced fighters, other planes that don't rely so much on maneuverability can be aided more by delta wings. Example: delta wing bombers can use the additional lift to carry more fuel and fly deeper into enemy territory where tankers are unable to go.

I think a delta wing has poor performance at low speeds, perhaps this is why all fast aircraft, Mach 3 and above, usually have a delta wing.

I have a few reasons the "pure" delta wing hasn't been used.

Number 1: Delta wings are made for fast flight and quick getaways. How many aircraft are used exclusively to get in quick, achieve objective, and get out before enemy has a chance to respond? NO! Thats not USAF Tactics! F-22, F-35, F-15 all air superiority fighters. They are meant to beat down other aircraft, not evade them.

Number 2: Deltas aren't great for low speeds and do add quite a bit of weight to the airframe. More weight=more lift need and less maneuverability in air.

Numer 3: Composite designs take the most advantage of both worlds.

I'd say the F-117 and B-2, but that'd be wrong as they only resemble the fact. The F-117A uses a Daimon type style and the B-2 is more like a flying wing/key shape.

I'm not aware of any in service 100% delta formation aircraft. The A-12 I believe was delta formed, waynos, MadG feel free to correct me on that.

My question is about pure deltas, not composites. I would not give the F-16 as a delta since it has back tail wings (I forgot the technical term for them )
The US has had a number of composite ones. The SR-71, the D21 Drone, The X-32,
The F-14 and F-111 its wings evolved into a delta wing...

Composed wings are in my opinion a different animal...
However adding canards I believe still respects the delta wing principle as such. In that respect the Rafale, Eurofighter, J-10, etc., are delta airplanes. For example the manoeuvrability issue doesn't seems to affect the eurofighter. I have seen many shows that state the incredible manoeuvrability of the Typhoon...
So why is that?

One issue for deltas is a low level flying...

Take a Mig-21Bis into a low and fast run and You'll get a massage that you probably won't forget (a pilot i know says it's like riding a jackhammer)

I don't know if this applies to Deltas in general or only Mig-21

The Rafael/Typhoon/Gripen/J-10 and to a lesser extent to LCA are no more true "pure" deltas than the SR-71 etc. The canards allow slow speed/high AoA flight etc - generally seen as the main problem with pure deltas.

Also, 'pure' delta wings can be far cheaper to make than seperate tailed configurations, which was Boeing's logic with the X-32.

Low level ride - that point probably relates directly to the MiG 21 rather than deltas in general, witness the TSR 2, a delta wing bomber that was designed specifically to give the best ever low level ride (you should read the test pilot reports, such as mach 1.1 while terrain following and drinking a cup of tea with no hands on the controls at all, how British ) The ride comfort of the TSR 2 when low and fast is still unsurpassed, reportedly, so thats not it.

I think the quiestion is far more complex than any of us on here can explain (except maybe kilcoo, who knows about this stuff).

If the question is related to pure delta's then the question itself is wrong. The reason for this is that the USAF is the only air force ever to put pure delta's into service (and all of them built by Convair). All the rest are clipped delta's (Mirage, MiG 21 etc), double delta's (eg Draken, Flagon F) notched delta's (Lightning) compound delta's (Vulcan, Concorde) or delta canards (Typhoon, Rafale etc)

The pure delta is actually quite inefficient without some 'fix' or other applied to the design.

An example of this is the pure delta of the Avro Vulcan Prototypes which was subject to horrendous problems until the compound curved and drooped leading edge was introduced for the production B.1, This compound leading edge was even further exaggerrated on the B.2 version.

For reasons such as this 'pure' deltas were generally a feature of prototypes and research aircraft in Europe and never made it to squadron service.

It is quite wrong to think of the wings of modern deltas as basic triangular slabs, the design of modern delta wings is much more complex than that. If it is inferred in the question that the wings of the Typhoon, Rafale Gripen et al are aerodynamically on a par with those of the F-102 and B-58 then that is a misconception that should be done away with.

I only wish I had the technical skill to explain why but alas I don't. That is not to say I don't understand why, only that I cannot find the words.

Also, why does nobody recognise the F-22 has having a delta wing? It is very definitely a delta and is quite close in shape to the Typhoons in terms of the aspect ratio.

[edit on 14-3-2006 by waynos]

The Avro Arrow ran into someproblems with stablity at higher speed with the delta. the problem is i remeber it correctly was that at about mach 2 the air would get compress at the front of the wing and run right down the front of the wing and off the tip. This is the reason for the wing "fence" that was built into the mid of the wing as it would help redirect the air over the top of the wing.

i persoanlly have a different thoery the delta wing has many configuration altough i should say modifications to the true design from what i understand they are very stable when flying from what i have worked out is that america doesnt use them becuase america gets its manuverability of its aircraft through unstable designs so it also needs an unstable wing they compensate for this unstable design using fly-by-wire which creates a very stable flight with great turning and manuvrability. on the other hand from what i understand other people chose a different appraoch to the task they added canards to there design although they also use fly by wire they rely on canards to get a better turn and manuverability of there aircraft there basically 2 appraoches to the same problem.