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Base Unit Lift duct Thrust Duct Motor Mounts Front Cabin
Centre Cabin Air Duct Cover Skirt R/C Installation
The duct was built as per Mark's diagrams but then mounted onto a base that can be removed from the model for modifications etc.
The biggest problem here is getting enough thrust to push the model over the hump when operating over water.
Many propellers were tried but with the duct as designed the model never achieved hump speed.
Having built an experimental small model with a 10inch duct I mounted this duct on the Griffon model. Using a 10 x 6 nylon prop driven from a 680 motor, via a 2.9/1 gear box, gave a dramatic increase in speed. Remember the model weighs in at 12lbs so more power was required compared to a much lighter model. My friend's Griffon model achieves hump speed with a duct that is only 1/2 inch bigger than Marks design.
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