You can always build a Type IXc that includes an FA-330 Bachstelze (Wagtail) gyro-kite that German U-boat crews used for observation purpose. Model is a highly detailed ABS vacuform with plenty of resin & metal parts suitable for display or RC conversion. Not sure if you could get up enough speed to actually tow a gyro coptor, but it would look great for a display when you aren't on the water. Kit is from Ota Gerza: http://www.rcsubs.wz.cz/en_index.php?sid=modely

http://www.rcsubs.wz.cz/en_index.php...ogale/ota&ii=3

http://www.rcsubs.wz.cz/imgota/ix_5.jpg