Twin Pond Master (oz7935)

About this Plan

Twin Pond Master. Electric twin sport seaplane model. For 2x Speed 400 motors and 4 channel radio.

Quote: "Electric Seaplane For 2 x Speed 400 Motors by Bob Hoey and Bill Warner.

My good friend Bill Warner lives on a small lake. Several years ago I built an Ace 'Puddlemaster' and Bill built a 'Pond Side' (both are the same airplane, designed by Scott Hartman). Both airplanes flew just fine and we quickly learned the fun of seaplane flying. We also learned some of the advantages of electric powered seaplanes. The most obvious - there was no noise to bother the neighbors.

Since we are both scratch-designers/scratch-builders from the early days of U-control, we quickly began to seek ways to modify and improve the PM's performance. We were annoyed by the pitch trim change associated with the high thrust line. One thing led to another, and Bill decided to replace the single, pylon-mounted Speed 600 with two Speed 400's mounted on the wings. Bill went through two design cycles, reducing structural weight and adding improvements each time.

After completing and flying his second Twin PM, and optimizing the battery selection, it became obvious to both of us that this was a real winner! With the wheel dolly taped in place it is even fun to fly off the runway. The Twin PM retains the same basic hull features, wing airfoil and tail shape as the original Puddlemaster, but there are some significant changes in addition to the twin-engine arrangement:

(1) Wingspan and chord were increased.
(2) Strip ailerons were added.
(3) Dihedral was reduced.
(4) Fuselage was lengthened.
(5) Structural weight was reduced.

The two 7.2 volt Speed 400's are wired in parallel and powered with either a 7,8 or 9-cell, 2000 mAh NIMI-1 battery pack, (8-cell works best). Flight times average eight minutes.

Fuselage: The fuselage sides are cut from two sheets of 3/32 x 4 x 36 in balsa. The sides are larger than 4 x 36 so you will need to add extension splices at the bottom and rear as shown on the plan. Use the fuselage side view for the pattern but add 3/32 to the height over the entire length to compensate for the sloping sides. Mark the bulkhead locations on the inside of each side piece.

Start by gluing the 3/32 wing support doublers and aft fuselage extension doublers to each side. Also locate and glue bulkhead 3A to the aft side of bulkhead 3 with the upper edge exactly 3/4 in below the top of bulkhead 3. Mark a centerline location on the bottom of each bulkhead. Sand a taper in the aft doubler as shown on the drawings. Set the two fuselage sides upside down and on edge on a flat surface and glue the two sides together at the rear..."

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