Mallard Bipe (oz7759)

About this Plan

Mallard Biplane. Radio control sport biplane model. For sport or pattern. Wing area 850 sq in, for 60-61 power.

Quote: "For some reason the majority of modelers find biplanes a fascinating type of aircraft. Today's trend toward nostalgia may explainit; it may be simply that the two-winged appearance turns us on. Who knows, the answer may be our dual personalities. In any event, I have been intrigued by bipes for a long time, and the Mallard represents my efforts to design an up-to-date two-winger that can match the maneuverability of a pattern bird, be relatively easy to build and fly, and yet have a real bipe look.

My home is in a wooded area where I have watched wild ducks on the wing landing and taking off. Their multi-colored appearance and maneuverability in flight led me to the name Mallard.

Mallard uses a tall fuselage to spread the two wings and, thereby, reduce any interaction between the two lifting surfaces. This also eliminates the construction of a fussy, difficult-to-align 'bird-cage' cabane, so typical of biplane designs. The trike gear is another unique feature that is a great help for smooth takeoffs and landings. If you look closely at the fuselage design, you will see that it has the look of a pattern ship, complete with sub-fin to smooth out four-point rolls.

The original thought was for retractable gear, but the ones I had available just wouldn't fit in the lower wing. You may want to include retracts, and I suggest Sonic System's, since they have a very low profile. This design's thrust toward pattern capability stems from my previous designs: Pathfinder, Super Pathfinder and the XL.

It has been said that there is a grow-ing discontent with RC Pattern, particularly C and D - a compelling reason to go to biplane aircraft and their particular style maneuvers. The new proposal to shift C to a bipe event (with D exclusively FAI) seems to make a great deal of sense. I believe my design will meet the Sportsman class requirements for the NSPA, as offered by Jerry Nelson, and it will make a good trainer for this event. Adding ailerons to the bottom wing should help ensure a hot roll rate, for the snappier advanced maneuvers.

Art Schroeder flew the ship on its first flight. That proved my theories. It's very maneuverable, with relatively soft stall characteristics. The ship is as fast as most pattern birds with a 60, but it can be calmed down with a good 40. It can do all the maneuvers that any pattern aircraft can - plus! I won't say more on its flying abilities, except to say its a real beauty.

CONSTRUCTION Building the ship can be accomplished in a two week period, including application of MonoKote.

Wings: The wings are very easy to build and details on construction of half the top wing should be enough, Use medium-hard balsa for spars and medium for ribs and sheeting. Pin a 3/8 x 1/4 spar to the plan and glue each rib individually to it. I usually use five-minute epoxy for this step. Epoxy the top 1/4 x 1/4, the 3/32 leading edge strip and the top 3/8 x 1/4 tap spar in place. Allow this assembly to set for about ten minutes and remove from plans. Add 1/4 x 1/4 spar on the wing's lower surface.

Draw a line across the ribs for the inset ailerons, and cut off each section in order to glue in the 3/16 x 1/2 strip. Set the aileron torque rod in place; this is a 1/8 rod that rotates inside a brass tube. Use the exact angles on this rod as specified on the plan. Cement in place the small balsa blocks at each hinge section, as per plan, and sheet the top section of the wing with 1/16 sheet. Put this section aside and build the other half in the exact same way..."

Mallard by Dan DeLuca, October 1974 AAM.

Update 31/05/2016: article pages, text & pics added, thanks to RFJ.

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