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Delta winged aircraft such as the Dassault Mirage III have an approach speed of 170 knots as specified by the manufacturer.

The Mirage F1 was designed to have a lower take off and landing speed than the Mirage III, what would it have taken to reduce the Mirage III landing speed to 135 knots by increasing wing area and reducing wing loading, and installing the F1 engine, and adding leading edge extensions (without adding canards)?

Could this be done by reducing maximum speed to say Mach 1.4 instead of Mach 2 without sacrificing climb performance?

Some figures: Mirage III Thrust: 60.8 kN Rate of climb: 83 m/s (16,300 ft/min) Wing Loading:274 kg / sq m

Mirage F1 Thrust: 70.6 kN Rate of climb: 243 m/s (47,835 ft/min) at high altitude

There is a formula relating change in stall speed to weight of aircraft, not sure if it is applicable here.

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  • $\begingroup$ It would be more efficient to reduce the static margin, as done on the Mirage 2000. $\endgroup$
    – Peter Kämpf
    Jun 1, 2019 at 16:28
  • $\begingroup$ Peter, do you mean moving the cg rearwards and reducing pitch stability, requiring fly by wire? $\endgroup$
    – stackex555
    Jun 2, 2019 at 9:29
  • $\begingroup$ Yes. That was done on the 2000, too. $\endgroup$
    – Peter Kämpf
    Jun 2, 2019 at 13:16
  • $\begingroup$ 20% decrease in approach speed would be possible? May not be possible to guess accurately without in depth study? $\endgroup$
    – stackex555
    Jun 2, 2019 at 15:36
  • $\begingroup$ Holding a bunch of stuff constant, to get from 170kt to 135kt approach speed at the same coefficient of lift, you’d have to increase the wing area by about 1.6. That extra wing would be extra form drag. Not sure how much of a contribution on total drag the wing is for the Mirage. $\endgroup$
    – MikeY
    Jun 2, 2019 at 22:46

2 Answers 2

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What you describe would probably work. In fact rate of climb and operational ceiling would improve. So too would maximum payload. But Mach 1.4 would have been a bad joke.

But your question reads a bit like "How can we improve on the Mirage III wing without doing all the things that were subsequently done to improve on it?"

One approach taken on the contemporary Convair deltas; F-102, F-106 and B-58, was to apply leading-edge camber with a conical profile, apex at the root and widening towards the tip. Developed by NASA, the technique significantly improved low-speed handling and, because it was designed to stay within the root shock cone, had surprisingly little effect at supersonic speeds. The second two designs were both capable of Mach 2. Even the F-102 just about reached your Mach 1.4, despite poor area ruling.

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"Could this be done by reducing maximum speed to say, Mach 1.4?"

Yes, but then it becomes valueless as an interceptor.

The delta does not lend itself to lift enhancing devices needed for slow flight, such as slats and flaps, nearly as well as a straight wing. Increasing camber is perfect for landing as it also increases drag.

Lowering wing loading will lower landing speed, but sacrifices top speed, because of increased drag. The larger wing will improve climb performance and maximum altitude.

But there are more options, the swing wing, seen on the Mirage G, or a smaller, more efficient wing.

And another, keep the blazing top speed, and simply build a longer runway.

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