I have no idea what most of this text means, which makes up the section immediately after the lead:
The long root chord of the delta wing and minimal area outboard make it structurally efficient. It can be built stronger, stiffer and at the same time lighter than a swept wing of equivalent aspect ratio and lifting capability. Because of this it is easy and relatively inexpensive to build—a substantial factor in the success of the MiG-21 and Mirage aircraft series.
Its long root chord also allows a deeper structure for a given aerofoil section. This both enhances its weight-saving characteristic and provides greater internal volume for fuel and other items, without a significant increase in drag. However, on supersonic designs the opportunity is often taken to use a thinner aerofoil instead, in order to actually reduce drag.
What is a "root chord"? What is "area outboard"? What is a "deeper structure", and why does that save weight? (Am I right in reading "enhances its weight-saving characteristic" as just meaning that it saves weight? If so, that's an awfully wordy way to put it. If not, it'd be good to clarify what it does mean.) Why is there an "opportunity … to use a thinner aerofoil"; is that a consequence somehow of the "deeper structure"?
I'm sure this all largely makes sense to someone who already knows the information this section is trying to express. It would be excellent if some such person were to intervene to make this clearer for readers (like me) who don't. Greg Price (talk) 06:27, 29 January 2026 (UTC)
- Have added two wikilinks as a start, root chord. Nimbus (Cumulus nimbus floats by) 07:55, 29 January 2026 (UTC)
- The structural advantages of a delta (low aspect ratio) wing are explained at Aspect ratio (aeronautics)#In aircraft, aspect ratio is linked. Very basically a high aspect ratio wing needs strong spars that taper towards the tip (stress reduces), a low aspect ratio wing (including deltas) do not.Nimbus (Cumulus nimbus floats by) 08:12, 29 January 2026 (UTC)
- Another missing link was Thickness-to-chord ratio. A 5 metre root chord 10% wing has a depth of 0.5 metres, can squeeze wheels and fuel in, a 2 metre chord 10% wing with a depth of 0.2 metres can not, the wheels invariably live in the fuselage.Nimbus (Cumulus nimbus floats by) 08:26, 29 January 2026 (UTC)
- Very helpful, thanks! I've fixed one link.
- The place you added that last link Thickness-to-chord ratio is on "deeper structure". I don't see the words "deep" or "depth" anywhere on that page, though, so the connection isn't entirely clear.
- From your comment here, I guess the idea is that "depth" is what that article calls "thickness"? And then that the thickness-to-chord ratio would be roughly constant between a delta-wing and swept-wing design, so that the longer root chord allows greater thickness/depth at the root, making room for wheels and fuel as you mentioned. Greg Price (talk) 09:18, 29 January 2026 (UTC)
- Structural considerations could be added to the thickness-to-chord ratio article, it mainly discusses aerodynamics though there are some 'shape' notes. I would understand a 20% wing to have a deeper structure than a 10% wing without seeing a drawing. It's really a subject for an aircraft structure design article which we don't have, too broad a subject that a general encyclopedia would be unable to cover, there are many aircraft design papers available on the internet. Nimbus (Cumulus nimbus floats by) 10:17, 29 January 2026 (UTC)
- Would it be accurate to replace "deeper structure" with "thicker structure" in that sentence? (And retain the new link to Thickness-to-chord ratio.) If not, is there some other rewording that would capture the main point that sentence is trying to make but do so in plainer language? Greg Price (talk) 07:30, 30 January 2026 (UTC)
- I believe the writer has used phrasing related to an aircraft's x, y, and z axis where x is longitudinal/lengthwise (longer/shorter), y is lateral/widthways (wider/narrower) and z is normal/vertical (taller/deeper). A common development with fighter aircraft variants is increasing design weight as avionics, fuel capacity and payload increase, this needs wider mainwheel tyres to cope with the load. It's common phraseology to say this variant had deeper wheel wells. If the designer couldn't make the wells deeper they bulged the covering doors outward, they did both on the F-4 Phantom, bulged skin panel on the wing top surface and bulged doors. Nimbus (Cumulus nimbus floats by) 09:05, 30 January 2026 (UTC)
- Thanks, that makes sense. Given that the helpful article you added a link to calls it "thickness", I think calling it "thickness" will be clearer to readers than "depth"; so I've edited that phrase to say "thicker wing structure". Greg Price (talk) 06:24, 31 January 2026 (UTC)