In the end an unstable canard layout was adopted, as it would give the greatest benefits to performance, as it gives a high onset of pitch rate and low drag enabling the aircraft to be faster, have longer range and carry a larger useful payload.
Canard or aft tail configuration?
2102
One of the two basic variants were 2102, which was a F-16
look-alike, but smaller and with side intakes.
2105
The other basic variant was 2105 which was of delta canard configuration. It was also tested with a chin intake.
2108
2108 was an other canard layout.
For an instability of 5-10% at subsonic speeds, which was
desired, Saab decided that a canard layout would entail a
lower technical risk as the canard can be weathercocked
turning the aircraft into a slightly stable one. This
cannot be done with an unstable aft tail configuration.
Other advantages with a canard is more lift during take
off and landing, 10% better supersonic turning performance
and lower supersonic drag. Also envisioned was the
possibility to point the nose off the direction of travel.
The canard can also be used as an air brake after
landing.
2107
The version most likely to compete with the canard layouts
had a dorsal intake, which meant a short and straight
duct. Wind tunnel tests showed that it would work well at
high angles of attack and that 2107 had better turning
performance than 2105. Saab judged the risks with the
dorsal intake as too large.
2111-4
2111 had a HIMAT-like, Rockwell designed wing. Subsonic turning performance was increased due to a lower induced drag and its aeroelastic properties, without performace reductions in other regimes. Note the leading edge flap on the canard, the double slotted leading edge flaps on the main wing and the small control surfaces near the engine nozzle.Span was 9% greater than for 2105, sweepback 10% less, wing area 13% less but weight 3% greater. It was cancelled in 1982 as at that time it wasn't possible to manufacture it with the correct aeroelastic properties.
The final result
2110
The image actually depicts JAS 39 Gripen, which is a
slightly refined form of Saab 2110.
No comments:
Post a Comment