Comparision of two basic canard configurations and their effects.

1. Canards
Close coupled or long arm?

2. What is canard
French for “duck”
Ducks have a layer of feathers around the
neck which improves aerodynamics
Canard is a control surface in front of the
wing
Lifting canard
Control canard

3. General effects
Loaded canard decreased drag at
supersonic speeds
Provides upload vs traditional tail download
Reduced need for elevon trim
Less drag in level flight
Unloaded canard only adds minor drag,
but improves lift and reduces drag in turn
Improved STOL performance

5. Close coupled canard
Increases instability level
Low pressure area at forward part of the wing
> dynamic instability
Does not shift to stability during supersonic flight
Improved pitch rate through angle of attack
range
Improved pitch onset and turn onset rate

6. Close coupled canard
Improved lift at high angles of attack
Improved instantaneous turn rate
Little effect at speeds above Mach 0,9
Reduced necessary wing twist
Reduced drag for a given angle of attack
Delayed stall; reduced trim drag
Significant improvement in L/D ratio

7. Close coupled canard
Vortexes improve wing response to control
surface inputs and improve control surface
effectiveness
Improved transient performance
Roll onset rate in particular
Improved control effectiveness at high angles
of attack

8. Close coupled canard
Reduced drag during supersonic cruise
Reduced centre of lift shift
Less trim drag
No effect on lift or drag during supersonic
maneuvers
Stall and spin recovery

9. Long arm canard
Canard vortex bursts early due to lack of
influence from the parent wing
No drag improvement at high AoA
No improvement in roll onset rate
Lift improvement limited to increase in
reference area caused by addition of canard;
no effect on the parent wing
Requires greater static instability margin to
achieve same overall amount of instability >
no dynamic instability

10. Conclusions
Close coupled canard is a better choice for
applications where maneuverability is
required
Long arm canard may be better for cruise
performance
Both canard configurations are superior to
a traditional wing-tail configuration

11. Presentation by Picard578
http://defenseissues.wordpress.com/
http://defenseissues.wordpress.com/2014/08/23/close-coupled-vs-long-arm-canard/