Lightning - delta wing

[nzhills]

Hi
On the Lightning, does anyone know why Petter, (the designer of the initial LIghtning), go for what amounted to a delta with a notch taken out of it and a tailplane? Would much be gained from a Skyhawk or Mig 21 like setup, i.e. a complete delta with a tailplane? There’d be more wing area, the wing close to the root would be thicker thus giving more possibilities for undercarriage stowage and putting fuel in the wings and he could of added some sort of flap. Conversely by putting the notch into the rear of the wing the total drag would have been less in a turn than the unnotched one, (aspect ratio would be lower on the non-notched example and thus the induced drag would have been higher). What are your thoughts?
Mark

[fdr]

Hi
On the Lightning, does anyone know why Petter, (the designer of the initial LIghtning), go for what amounted to a delta with a notch taken out of it and a tailplane? Would much be gained from a Skyhawk or Mig 21 like setup, i.e. a complete delta with a tailplane? There’d be more wing area, the wing close to the root would be thicker thus giving more possibilities for undercarriage stowage and putting fuel in the wings and he could of added some sort of flap. Conversely by putting the notch into the rear of the wing the total drag would have been less in a turn than the unnotched one, (aspect ratio would be lower on the non-notched example and thus the induced drag would have been higher). What are your thoughts?
Mark

The lightning did have flaps....
the angled (swept) flaps are effective at high deflections, there is a vortex structure that develops due to the crossflow, and that is stable, and can increase CL at high flap deflection angles, where otherwise CL is only marginally increased, but drag increases... The flaps on the lightning are quite effective. The MiG-21 had a nice fowler flap design, the A-4 had a split flap which is OK for CL but comes with lots of drag. The Mirage, no flaps, the constraint of having a tailless delta.
the aspect ratio of the notched delta was substantially greater than the other deltas, and drag at high alpha is far better. The notch still achieves a vortex lift at high alpha from a vortex formed immediately behind the LE, that gives a greater alpha capability than a straighter wing would have, common to all deltas.
Petter designed a neat MLG that was a clean installation and which had an efficient structural mass fraction.
fuel volume was restricted by the design, and that also misses out on wing bending moment relief, but the plane was built for fairly high g anyway, so the structural penalty of having fuselage fuel only for clean config is not that great.
Having 2 big bunsen burners made the plane work for it's intended task, that of being a point defence interceptor, short range, rapid response, high rates of climb, and fair turn rates for operating inside an ADIZ environment. Similar brief for the MiG-21 and Mirage, but the 21 could do a fair ground attack, and the Mirage had some capability. The scooter was predominately a ground attack aircraft, and had a very good load carrying capability for its tiny size.
Petter designed a neat plane. The change of the outer sweep and its twist improved the handling at low speeds, but many British aircraft went through similar wing LE changes to improve handling.

[alf5071h]

The decision may have been influenced by the debate about the setting of a high or low tail plane.

The high-tail, delta wing Javelin had many low speed problems. Many of the theorists (RAE) backed the high tail option for supersonic aircraft, but Petter resisted.

The Short SB5 research aircraft evaluated both high and low set tailplanes at low speed; the fears of the low set tail were unfounded.

The notched (split) delta platform with separate low set tailplane had advantages over a pure delta.

https://en.wikipedia.org/wiki/Short_SB.5

https://en.wikipedia.org/wiki/English_Electric_Lightning (https://en.wikipedia.org/wiki/Short_SB.5)

[Asturias56]

Mason (British Fighters) said they started out the design with less sweep but kept increasing it to cut drag no mention that a delta was ever considered - and it was only meant as a high speed test aircraft to start with.

Gunston (Early Supersonic Fighters of the West)has about 30 pages on the Lightning - According to him (and Beaumont) the Brits were impressed that as standard F-86 could break the sound barrier with swept wings and that's what they put on the P1. There was enormous amounts of heat and arguments about the tail plane but the wing? Hardly mentioned. It worked.

[hans brinker]

Thought this was a thread about lightning striking the wing of a Delta Airlines airplane, in light of the recent 787s/350s with lightning damage. Went from mildly confused to somewhat embarrassed. Back to scheduled programming...

[gums]

Better luck next time, hans!

Gums chuckles...

[Zar_1]

Mason (British Fighters) said they started out the design with less sweep but kept increasing it to cut drag no mention that a delta was ever considered - and it was only meant as a high speed test aircraft to start with.

Gunston (Early Supersonic Fighters of the West)has about 30 pages on the Lightning - According to him (and Beaumont) the Brits were impressed that as standard F-86 could break the sound barrier with swept wings and that's what they put on the P1. There was enormous amounts of heat and arguments about the tail plane but the wing? Hardly mentioned. It worked.

Didn't the F-86 have massive amounts of Mach Tuck and Aeroelastic Flutter near the sound barrier??

[fdr]

Better luck next time, hans!

Gums chuckles...


that was Mr Petter, not St Peter....

[washoutt]

The wing looks like a normal swept wing, but for its wingtip. Instead of a trip aligned with the direction of flight, the tip is aligned perpendicular. Is that a constructional consideration? I imagine that a tip perpendicular to the direction of flight is easier to construct and probably stronger than a normal tip, with a very thin and long aft part.