The Joined 1 was developed in an attempt to break the world speed record for model gliders and the airfoils chosen reflect the intention to go fast. The EH1/7 is a thin low camber section.
The Joined 1 has no washout and this is unusual for any flying swept wing. John Yost, the team aerodynamicist was surprised that it would fly at all. It was extremely pitch sensitive at speed and Hans-Jurgen said that he had to line it up and take his hands off the sticks during the speed runs. Any attempt to alter its line was met with wild pitching.
Consider that the FAI speed course is a measured distance of 200 meters and the maximum height is 50 meters. Now consider that the Joined 1 covered the distance in about 2 seconds.
This gives a speed of 360kph or 223 mph! or about 1/4 of a second reaction time at the height it had to fly.
Unfortunately the timing was done with a human pushing the button and the reaction times become significant at such small increments in time. Thus the record was not allowed.
The Joined 2 is identical in construction except for leading edge devices and 4mm of washout. This is measured from the trailing edge at the wing tip, introduced from the halfway point of each wing.
These modifications greatly improved the low speed handling characteristics but slashed the top speed to around 260kph or 160mph.
Here you can see Hans-jurgen setting up for bagging the wing
Here is another shot which shows a where the spar was situated. Don't position it like this!
Check out that skinny EH1/7 airfoil. Thank you John Yost!
This is a view of the leading edge devices (LED's)on the Joined 2
And here is another view from the side.
