"Douglas Eagleson" wrote:

http://www.aoe.vt.edu/~mason/Mason_f...AlphaNotes.pdf

Here is a study that mentions a critical aspect of the issue of canard flight.
High angle of attack allows for very fast roll rates in general. A wing
designed for high angle of attack becomes a superior wing in general.

Where does it say that? What was the max roll rate of the Wright Flyer? AJ-37
Viggen? A-4E Skyhawk? F-5E Tiger?

Several transport aircraft and a few tactical aircraft have been tested using
the Coanda effect to allow flight at very high AoA. However, that high AoA
capability sacrificed considerable capability at low AoA / higher speed. Show
me where a high AoA capability has added to overall wing performance...

On page 9-10, regarding the general case, it says:

"Control effectiveness tends to diminish as the angle of attack increases."

It follows with a SPECIFIC DESIGN case:

"Here, differential canard is used to make up for the loss of rudder
effectiveness."

Note that NOTHING is said about a lack of horizontal stab, or inherent
superiority of any general scheme! Note also that several aircraft (e.g., F-14)
use differential horizontal stab to augment roll rate, so a canard has no
inherent advantage there.

Please show me a roll rate vs AoA chart for ANY fighter airplane (or ANY
airplane, for that matter, that has higher roll rate at higher AoA!


Also, it specifically supports my contention that performance characteristics
are DESIGN SPECIFIC! On page 9-5, specifically referencing lateral and
directional control of canard aircraft, is:

"One of the complications associated with canard aircraft is the wide
variation in these characteristics with canard setting. The trailing vortex
system from the canard interacts with the leading edge vortices of the main
wing, forebody vortices and also the vertical tail. Thus the lateral/directional
characteristics of canard configurations play a large role in deciding if a
canard configuration is practical."


A f-22 uses a special thrust vectoring to achieve high angles of
attack, it does not use a superior wing design. A major fact shown
was the roll rate as angle of attack is varied. Reliance on thrust
vectoring to compensate for a wing design reduces the roll rate.

Roll rate is a speed to turn in. And the degree of roll appear
amendable to only a f-16 challenge.

In dogfights it has a deficiency. In stealth it likely has
superiority. Maybe a tradeoff was accepted. As long as pilots know of
this limitation they may alter tactics to overcome lower performance
ability.

In decision making many factor appear and my guess is it is to be
termed a fourth generation dog fighter and a fifth generation stealth
fighter.

Roll rate is another envelope variable and the lack of speed to turn
appear to make another maneuver available to be considered. A basic
cork screw as a prelude to turn is either to be followed or not
followed by the attacker, say an F-22. A leading enemy can expect the
F-22 to not follow.

An F-22 cannot keep up.

As a result all acts to avoid the US fighter can be successful break
off maneuvers. If you do not match the cork screw, you also loose. A
whole class as a basic dogfight disappears.

It is a huge compromise design, the non-canard F-22.