Mighty Mini Sea Duck

Horseman3381

Well-known member
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At Flite Fest 2019 there was a gentleman who was flying around a 60% sea duck he had built. He didn’t have plans for it and told me he had just printed out a set of scaled down plans and “winged it” as he was building. Ever since I saw it, I knew I one day needed to build one.

Finally Last fall I decide to modify the plans and build one for myself. I have gone through 3 variations of the plane to date, and believe I have all the kinks worked out.

The plane flies amazingly. With A-pack motors it is super docile and a nice easy lazy flyer. If you put F-pack motors in, it can slow down and fly docile, or you can turn it up and easily do loops and rolls to your heart’s content. Both motor configurations allow for easy take-off from land, water or snow.

I fly the plane with a 3s2200 on F-pack motors with a 6 min flight I generally have a little over 50% battery remaining. When I tried to fly with a 3s850 and 3s1500 I had to move the battery pretty far forward to get the CG to balance.

Here is a photo showing it's scale. The middle one is the FT Sea Duck and the bottom plane is a 180% Sea Duck. The 180% is no longer with us as I tried to get a little too acrobatic not enough mistakes high. I will rebuild it this fall while fixing a number of design flaws, and post about it when it rebuilt.
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Specifications:
  • 3’-0” Wingspan x 2’-5” Long
  • Building Materials:
  • 3 sheets of foam board
  • 2 popsicle sticks
  • 1 wood bbq skewer
  • 3 FT mini control horns
  • 2 FT mini firewalls
  • Y-Power harness (if using 4 channel receiver)
  • Up to 3 servo wire extenders
  • 4 channel receiver minimum
  • FT A-pack or F-pack Motors & ESC’s
  • (3) 5g servos
  • 5x3 3-blade props
  • 3s 850mah to 3s 2200mah battery
Plans can be found here: Resource Page

Build Notes:
When building the plane, follow the FT build video for the full-size plane. The only 4 differences between the Mini and Full-Size builds:
  • The wing spar is a single piece in lieu of 3 pieces. This should be mounted with the U spar in the upright orientation.
  • The aileron servos are mounted 90 degrees from the full-size version with the wires facing the fuselage.
  • In the pontoons there are only single spacers on each side of the strut instead of double.
  • On the fuselage rear bulkhead, there is a partial depth cut line ¾” from the bottom. When installing this, do not glue above that line as with the small top hatch, it is tough to access/mount the receiver in this plane, so I left this as an access hatch for that purpose. It stays closed with friction.
The plans are laid out where you can install functioning rudders if you want. However, with the smaller nacelles it will be a challenge to fit the rudder and aileron servos in the same nacelle.

I designed 3D printed headlights and a nose cleat for the plane as those are iconic features of the Sea Duck to me. I have included these in the resource as a .stl file with the plans.

Design Notes:
When I scaled the plans to 60% I made the following changed for version 1.0:
  • Scale up/modify all cuts and folds to work again with the 3/16” foamboard.
  • Modify the size of the nacelles to work with the mini power pod.
  • Update the wing configuration to keep the same shape as the full size.
For version 1.0, the build went pretty easy by following the build video for the full-size plane. There were a few spots where some trimming /modifying was needed, but overall went together easy. The biggest issue was that when using the CG location from the full-size Sea Duck, the plane was very tail heavy. The CG ended up needing to move forward 3/8”.

Version 1.1 contained the following updates:
  • Updated the location of the CG indicators.
  • Increase the size of battery tray to allow for battery to be mounted further in the nose.
  • Update the wing spar to a single piece.
  • Added hinge point on rear hatch to allow for easier access to receiver.
Version 1.2 (current) contained the following updates:
  • Reconfigured aileron servos cutouts to allow for easier/cleaner installation.
  • Modified the size of pontoons for easier/cleaner build.