Cormorant MPUAV Exhaust Nozzle Door

Photo of Darren Cooper, Anthony Sanchez, Jon Urrutia Students: Darren Cooper, Anthony Sanchez, Jon Urrutia

Sponsor: Lockheed Martin

Date: Fall 2007


  • Must withstand temperatures up to 350°F
  • Must be resistant to saltwater corrosion
  • Must open/close and lock within 2 seconds
  • Must allow room for an inflatable rubber seal to be installed
  • Must withstand a 5 psi pressure differential
  • Must have a safety factor above 1.5
  • Must fit within the nozzle dimensions provided by Lockheed Martin
  • The door must lock in both the up and down position


To design an exhaust nozzle door with a locking mechanism to prevent water from entering into the Cormorant's engine during saltwater submersion.


The solution proposed by the design team consisted of a triangular door with four rib stiffeners welded to the back of it. The ribs are then welded to a shaft that is supported by bearings, thus creating a door-hinge assembly. The door is actuated by a Yates pneumatic cylinder which is fastened to the door between the two inner ribs. The team chose pneumatics because the Cormorant had compressed air tanks on board already to pressurize the hull of the craft. The locking system uses two locking pegs that fit into holes placed in the rib supports. The same set of pegs is used to lock the door in both the up and down position. The lock pegs are actuated by a spring extended pneumatic actuator. The spring extended feature of the actuator causes the locks to passively slide into the lock holes without any additional power. The locks can then be released using the pressurized air to retract the actuator, which in turn retracts the locks.

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