Wide Body option

for Challenger II

Part of the problem with doors on the Challenger II (I don't know about C1) is that it's designed with a sharp cut-in from the rear of the door to the fuselage.  This causes drag and turbulent air going back to the tail.

People have said this is a large part of the problem with yaw stability when flying with doors.  Some people have put vortex generators on the doors to minimize that effect.

Some clever person decided to make the fuselage conform to the doors.  He put curved tubes at the rear of the cockpit, just behind the passenger's shoulders. These tubes match the curve of the door.  When the fabric is put on the plane, it is stretched over the new tubes.

Now, with the doors on, you have a smooth surface from the widest part of the windshield, down the doors, down the fuselage sides to the engine.

Here, just at the edge of the rear cockpit, you can see the curve they’ve added to the shape of the fuselage. Once the fabric is put on, it gives a seamless, smooth airflow back to the pointy rear for no turbulence and minimum drag.

Some building details:

http://www.erieairpark.com/wide_body.htm

I'm told this was originated by Paul Arney of Bala, Ontario, Canada.  Paul tells me he sent the drawings to QCU.