Hi,
what are the pros and cons of duck wing configuration ?

Thanks, Mark

Are you asking about a CANARD layout?
Allan

Canard is the French word for duck.

This sounds quackers to me!

I heard than Canard (Duck) configuration is unstable.
Mark

Actually, a canard is very stable. When the stabilizer stalls, the nose drops and restores the lift.

What IS unstable is the pilot's viewpoint since the airplane appears to be flying backwards.

Dr.1

Like any layout the canard can be either stable or unstable based on where the balance point is located. Where it becomes difficult is in the yaw plane where due to the CG being very far to the rear of most designs there is a need for a very large vertical tail area or the design needs to sort of be a mid wing like much of Rutan's design work.

My Canard, seen at the left, is very stable. I have flown it in gusty 30MPH wind and had a ball. I am more daring with it because it is a SPAD. I have the CG a bit to the rear. When it was further back it could get into a high speed stall that was deadly if there was little altitude. As scary as anything I have ever seen flying. I also had to reduce elevator travel to prevent the high speed stall. I insist that the plane accept any control input I give it. It does. If the wind is up and I want to fly, I take the Canard.

interestingly my canard (own design - based on Andy Lennon's canard design chapter in RC Model Aircraft Design) is quite tricky to fly in gusty conditions. It's far easier in still air.

It is hard to land - the landing approach has to be very shallow - this I believe is because the rear wing is nowhere near stall and is always in a (relatively) low drag configuration, with small amounts of induced drag?

The design has swept aft wings and fins on the wing tip.

it is stable in pitch though - can't stall aft wing.

I find my Starliner to be very stable (Mk IV version pictured below), yet responsive. One of my favorite manuvers is to climb up about 200ft then dive down under full power, level out about 30ft off the deck going about 100mph, roll over to 90 degrees of bank and pull full up elevator. The plane will do a 180 degree turn in about a 50ft circle. You can hear the air turbulance off of the canard during the turn. Gets everybodys attention every time!

On landing, I slow down to just above minimum speed on downwind and hold a slight nose up attitude with elevator and use power to control the descent. Over the runway at about 2ft, all power is off and flare out. The plane touches down on the mains real nice.

It is a fun plane!

Later!