A Rocket Mass Stove by Juured in Estonia.

 
   
 
 

When a rocket stove burns it draws air in pulling the flames into the stove. You can feed a rocket stove by placing a long log in the fire box that sticks out the top while it burns at one end in the fire box. The wood is gradually consumed without any smoke escaping. This rocket stove is by Juured in Estonia. Rocket stoves have very efficient combustion, where the furnace temperature ranges from about 1000C up to 1100C.

 
 
 

This book by Ianto Evans and Leslie Jackson is without doubt the best guide you can find to building your own rocket mass heater.