Originally posted by Number23
Why? What are the advantages/disadvantages of the delta/canard layout?
Simply put (for the designs you mention) - high speed maneuverability.
The US don't seem to like canards from the outside, but looking closer, they didn't design a new fighter for high speed maneuvering before TVC
became a serious option.
This allowed them to prioritise radar shape on the F-22 (avoid the canard fuselage junction in the forward quadrant radar 'wetted' area) while using
TVC to trim the aircraft for supersonic flight (giving them back good maneuvering capabilities).
There are a number of factors to consider over which is better, some of these are:
1. A canard generates upthrust when pitching nose up, while a traditional elevator generates a downthrust - thus a canard should
better sustained turning performance.
2. A canard can generate a little upthrust in steady level flight, allowing for a smaller wing - meaning less inertia & damping, thus better dynamic
response rates (in pitch and roll).
3. A canard when pitching nose up will induce a downwash over the main wing, reducing its effectiveness, which conflicts with (1) and (2). Increasing
the distance from canard to wing can help offset this (Eurofighter).
4. A canard can be used as a replacement for a LERX for high AoA flight, and its normally more efficient in cruise. Close coupling of canard and wing
helps achieve this (Rafale).
5. With a canard, the main wing can be placed further back, hence the c.g of the aircraft is further back, hence the gear is further back, hence more
aggressive rotation angles can be used for take-off. The canard also is better at inducing rotation than a tailplane.
6. A canard requires a junction between wing and fuselage - this junction is harder to hide on radar. Its preferred to hide this behind the main wing
on an elevator (like the F-22).