To put it simply, there are a lot of aerodynamic surfaces on my New Glenn model. The most important are the main fins, which are located at the aft end of the rocket. These fins are 1/4″ thick clear acrylic fins (currently still in their protective blue plastic cling wrap). They are of a through-wall design, so they will be epoxied to the motor mount tube as well as to the inside of the aft module. A small fillet of epoxy will also be used on the outside joint. They have a root chord of approximately 10.8 inches, a tip chord of 5 inches, and a height of 8 inches (measured from the 6 inch primary airframe). The root chord is contoured to match the profile of the rocket as it transitions from the 6 inch primary airframe to the 7.7 inch aft module. While alignment is handled primarily by the slotting, the fins also utilize locking tabs, which fit into laser cut notches in the middle and aft centering rings. The primary function of these tabs is to keep the fins square with the airframe during construction, but do provide an extra level of assurance for minimizing fin cant.
The second set of fins are the forward canards. Located 29.5 inches from the nose end of the rocket, these fins actually provide a destabilizing force. For this reason, the rocket will have to fly with at least 1 kg of payload. Each of the four canards has a root chord of 4.3 inches, a tip chord of 1.4 inches, and a height of approximately 1.8 inches to maintain the scale of the rest of the rocket. These are made from 1/4 ” thick plywood and are painted white and blue. Unlike the main fins, the canards are surface mounted so as not to interfere with the main parachute, to whose bay they are mounted. To provide additional attachment strength, each canard will be held by two pair of 3D printed PETG brackets with 10-24 binding posts. These brackets will be epoxied onto the airframe and provide approximately 1 square inch of bonding surface per bracket pair. Due to launch rail considerations, these canards will be mounted 45 degrees off their intended position, aligning with the main fins.
The final set of fins are the strakes. These two fins are also made from 1/4″ thick plywood and painted white and blue. Like the main fins, they are contoured to match the profile of the transition in the aft module. They have a root chord of approximately 14.9 inches, a tip chord of approximately 2.8 inches and a height of approximately 2.6 inches to maintain scale. Like the canards, the strakes are surface mounted, but this is because they were not originally considered for inclusion in the model, so the appropriate accommodations were not provided. To provide additional attachment strength, each strake will be held by two pair of 3D printed PETG brackets (same as used for the canards) with 10-24 binding posts. The strakes, each 180 degrees apart, will be mounted 45 degrees off of the main fins and 90 degrees off from the launch rail.
Aerodynamics were not a major consideration (or rather, more drag was considered better to lower the max speed and apogee for a certification flight), so all fins will keep their square leading and trailing edge profiles. This also has the benefit of decreasing the work required on the fins and maintaining the same standard of quality for each fin.