BJ-4 Information?

The BJ series of gliders were a collaboration of Pat Beatty and Fritz Johl.
The objective was to explore radical design options to find the next
quantum leap in performance.

Versions had everything from complex camber changing mechanisms to a
bicycle chain driven variable span system.

The gliders were revolutionary in many ways and enormously strong. They
were also made of obsolete materials for extreme performance. The BJ4
was made obsolete by the composite materials used in the Kestrel, ASW12
and the Nimbus - which it met at the worlds in Marfa.
One story from that contest is that on a retrieve, a passing driver had
the roof of her car removed by the wingtip of one of the BJ4s. The wing
was repaired but it was only some time later that it was discovered that
some of the rivets in the root centre section had sheared.The fit was so
tight that the damage was not visible.

There are a surprising number of survivors, both of the gliders and
their designers and builders. Dave Mortimer - The current chairman of
the Soaring Society of South Africa worked building BJs in his youth and
still has a BJ4 hanging in his factory. Peter Eich who also worked on
construction has a couple (BJ2 and BJ4) - I believe the BJ3 was
cannibalised for the BJ4.

Having helped Peter rig his BJ4 for static display a couple of times I
have two observations ,
1] the design and workmanship is exceptional, the flaps retract into the
trailing edge with tiny clearance, and
2] the weight is extreme. I thought my 19m Kestrel had heavy wing
panels. Definitely designed for high wingloading circumstances...

Pat Beatty died some years ago, his daughter Karin works for Jonker
Sailplanes. If you want more information you could start there...

If you know where to find him, Fritz Johl is approaching his century,
and building very large scale radio controlled gliders with - you
guessed it - amazing complex variable geometry wings.

There is an interview of Fritz done for the 2001 worlds in Mafikeng that
I will have to see if we can get into digital format...

Two outstanding gentlemen.

Cheers
Bruce