a bit too high-tech methinks
the biplane on the right clearly has a cubic force-field
(
PedroHin Come along & ride on a Flantastic Voyage,
Sat 20 Apr 2013, 12:52,
archived)
The slow blade penetrates the shield
(
Klangtarnflatchslapper looks just like a Telefunken U-47,
Sat 20 Apr 2013, 13:00,
archived)