Talk:Delta wing

‹See TfM›

Advantages

"The primary advantage of the delta wing design is that the wing's leading edge remains behind the shock wave generated by the nose of the aircraft when flying at supersonic speeds, which is an improvement on traditional wing designs."

Isn't this just a matter of the sweep rather than the delta planform? For example, the English Electric Lightning and MiG-19 have rather severe leading edge angles for this reason, even though they are not deltas. -- Paul Richter 09:52, 22 Nov 2004 (UTC)

The delta wing has much the same advantage as the swept wing:primarily a delay of critical mach of 1/cos(angle of sweep)

The wing is as if it were flying at reduced speed, reduced Mach number, and reduced dynamic pressure.

 effective speed = V cos(L)
 effective Mach  = M cos(L)
 effective q     = 0.5 rho V^2 [cos(L)]^2

where L is the sweep angle, V the airplane's speed and M its Mach, rho the air density and q the dynamic pressure.

The dynamic pressure term shows that the wing will have not only reduced drag but also reduced lift since:

Lift = Cl x A x q where Cl is the coefficient of lift and A the Area Drag = Cd x A x q where Cd is the coefficient of drag and A the Area

Suppose a swing wing aircraft is flying at its critical Mach number. If the wing then is swept back from 0 to L degrees the lift reduces by a factor of [cos(L)]^2, and the Mach compressibility effects on the wing's airfoils decrease eg shock wave formation. It is then possible to increase the speed by a factor of 1/cos(L).

These are simplifications for a swept wing; deltas are similar but far more complicated in real life due to the formation of vortices at the leading edge root that has a positive influence on handling and lift.

Alexander Lippisch

I don't know why Dr Alexander Lippisch is not mentioned in regards to the Delta wing: he had developed flyable swept wings in the 1930s and 1940s and proposed a surpersonic delta in 1940. In 1945 his DM-1 glider was shipped to the USA for study. His P.13a represents perhaps the first proposal to develop a supersonic delta.—Preceding unsigned comment added by Frederick Munster (talk • contribs)



You are right. The reference to Neythen Woolford is a furfy I believe. He is a kid on facebook and appears in no other published histories of Delta wings I have ever read. I'm suspect someone has vandalised the entry and sustituted their own name to achieve notoriety. It is demonstrable that Lippisch was the pioneer of Delta wings in Germany prewar and postwar GregOrca (talk)

Carnard

The explanation of the canard in the 3rd paragraph is a bit confusing. I've cleaned up the language a bit, but the point is still unclear. Attributing designs incorporating canards to unstable platforms and FBW doesn't seem accurate. The F-117 and F-16 are inherently unstable and neither have canards. FBW and instability (due to more radical, effective designs) do exist symbiotically these days, but that is independent of canard use. While the EF-2000, Rafale, etc. are more advanced designs and use canards, that has more to do with the increased effectiveness of delta-wing aircraft with canards, not necessarily instability or FBW.--Jonashart 20:13, 27 July 2006 (UTC)

That 3rd paragraph reads much better now. Sorry, took a while to get back to reading it. Nicely done, whomever is responsible.--Jonashart 15:44, 19 April 2007 (UTC)

Reorganise?

The article seems to alternate between historical ordering and description.

Perhaps the better structure would be:

1. history
   1. before WWII
   2. later development
   3. current status
2. discussion
   1. advantages
   2. disadvantages
3. list of types

m.e. 05:25, 24 November 2006 (UTC)

Support. - BillCJ 05:41, 24 November 2006 (UTC)

suggested in the 17th century by Polish inventor?

Claims that Kazimierz Siemienowicz had pioneered delta wings had been rejected [1] before, but were re-introduced once again [2], giving e.g. a NASA source that says .... proposed ... delta-shaped stabilizers to replace the guiding rods.... These stabilizers are simple fins, as on an arrow, not large lift-creating wings for a supersonic airplane. The sources do not back up the claim "Conception of this wing and its name" and the addition to Category:Polish inventions. -- Matthead  Discuß   11:09, 20 July 2009 (UTC)

If that is the case, be WP:Bold and remove the claims. --TraceyR (talk) 13:40, 10 November 2009 (UTC)

"undesirable characteristics"

This sentence seems to be complete rubbish:

"Pure delta-wings fell out of favour somewhat due to their undesirable characteristics, notably flow separation at high angles of attack"

Flow separation at a high angle of attack is exactly what is desirable....

Flow separation will always occur over a wing at a certain angle of attack. The higher the better...

This needs to be deleted or changed. Jez 006 (talk) 16:35, 15 April 2010 (UTC)

I agree that pure delta wings have fallen out of favour when compared with other planforms. I disagree that this is due to flow separation at high angles of attack or any other undesirable characteristic. This looks like somebody's original research. All wings exhibit flow separation at high angles of attack, not just delta wings. In fact, there are grounds for saying it is conventional wings that exhibit flow separation at high angles of attack leading to a stall, whereas delta wings don't exhibit a stall so flow separation can't be a problem.

Any discussion about the decline in popularity of the pure delta wing doesn't belong under the heading Delta-wing variations. Dolphin (t) 05:01, 18 April 2010 (UTC)

Glad you agree. It is the case that pure delta wings experience flow separation at lower angles of attack than double delta wings, delta wings with canards or delta wings with a chinard configuration, but this is not what has been written! I'll change it soon Jez 006 (talk) 11:03, 18 April 2010 (UTC)

It seems this paragraph is mostly incorrect as well:

"Another advantage is that as the angle of attack increases the leading edge of the wing generates a vortex which remains attached to the upper surface of the wing, giving the delta a very high stall angle. A normal wing built for high speed use is typically dangerous at low speeds, but in this regime the delta changes over to a mode of lift based on the vortex it generates. The disadvantages, especially marked in the older tailless delta designs, are a loss of total available lift caused by turning up the wing trailing edge or the control surfaces (as required to achieve a sufficient stability) and the high induced drag of this low-aspect ratio type of wing. This causes delta-winged aircraft to 'bleed off' energy very rapidly in turns, a disadvantage in aerial maneuver combat and dogfighting. This can be solved with relaxed stability, strakes and canards.[citation needed]"

For example:

"Another advantage is that as the angle of attack increases the leading edge of the wing generates a vortex which remains attached to the upper surface of the wing, giving the delta a very high stall angle"

As the angle of attack increases from what? It remains attached until when? Yes they generally have a higher stalling angle than conventional aerofoils but just to say a "very high stall angle" is pretty misleading... What defines a " very high" stall angle?

"A normal wing built for high speed use is typically dangerous at low speeds, but in this regime the delta changes over to a mode of lift based on the vortex it generates"

Delta wings are especially dangerous at low speeds, more so than normal wings. At lower speeds delta wings produce less lift and more drag than normal wings... This is why delta wings are more difficult to land, because at low speeds they experience a sudden loss in lift. This is why the concorde had such a high landing speed.

"The disadvantages, especially marked in the older tailless delta designs, are a loss of total available lift caused by turning up the wing trailing edge or the control surfaces (as required to achieve a sufficient stability) and the high induced drag of this low-aspect ratio type of wing. This causes delta-winged aircraft to 'bleed off' energy very rapidly in turns, a disadvantage in aerial maneuver combat and dogfighting. This can be solved with relaxed stability, strakes and canards.[citation needed]"

I can't agree or disagree with this, but there are no references. Since the previous sentences are not correct I doubt the accuracy of anything else that has been written.

Jez 006 (talk) 11:59, 18 April 2010 (UTC)

Conrad who?

I have read everything I could find on Conrad Haas and nowhere does it say he investigated or experimented with wings of any kind. All the documents ever talk about is triangular fins. I'm sure someone is going to tell me wings and fins are one and the same. They're not. All fins do is line up into the wind behind the center of gravity. The whole purpose and function of a wing is different. Wings support the weight of the air vehicle to which they are attached, and they do it specifically by not lining up into the wind but by assuming a non-zero angle across the wind vector so as to deflect air downward, lift being the "equal and opposite reaction" to the downward deflection of the air. So what the heck does Conrad Haas have to do with the invention of the delta wing? You don't need to know anything about flight trim to make a fin work, but if you don't know flight trim, you don't know the aerodynamics of winged flight. Sorry Conrad, but you did not invent the delta wing. Maybe it was the butterfly that just landed on your shoulder.Magneticlifeform (talk) 01:23, 20 October 2010 (UTC)