Plastic Figure Showcase Marx Exploding Submarine Marx-A-Copter Mark McDermott is another person who I have know for years. He has a wide and very interest collection. Recently Mark showed the Marx-A Copter which contains the exploding submarine on Facebook. Mark has given me permission to share these photos with you.
Plastic Figure Showcase Marx Exploding Submarine Marx-A-Copter The Set
The Marx-A-Copter set is an interesting set it contains a helicopter and an exploding sub. 
The helicopter is on a tower that flies around your playmat. The idea to fly it around to get it over the submarine. 
The idea is to tilt helicopter so you can dropped your bombs on the submarine.
Here we have the three bombs and man on a stretcher
The playmat is heliport with two lanes.
Plastic Figure Showcase Marx Exploding Submarine Marx-A-Copter Submarine
The submarine is done in red and gray. Mark said this submarine is different for the one from in Cape Canaveral playset. I be honest I have never seen either.
The submarine has three parts. The top is gray. Bottom and conning tower are red.
The spring goes on the red bottom. I will have to find ifthe spring is the same as the spring for civil war exploding bunker.
Here is instruction sheet showing how the exploding submarine works
Plastic Figure Showcase Marx Exploding Submarine Marx-A-Copter Box
The box has nice graphics
The side of the box has Sikorsky Service Center Sikorsky Helicopters is one of the first companies to develop helicopters.
This is a very interesting set. I see it could give hours of fun to its users. What are your thoughts.