Test Flight Report – Paradigm One

by Obi Mapua

1. The Paradigm is a “2-meter” pattern plane for F3A pattern competition designed by Obi Mapua. It has a fuselage length of 77 ½” (1.97 m) and a wingspan (now) of 74” (1.88 m). The fuselage is made primarily of balsa wood. The wing is foam core with balsa sheeting over the core. The model is finished in Monokote. Power is Supertigre 2300 (23cc-1.40) with a Mintor tuned pipe. Prop is a 17 x 10, Takeoff RPM is 7800-7900. Radio is a JR PCM 9X. Model weight is 10.5 lbs. (4.77 Kg.)

2. The Paradigm 1 had 2” (52 mm) from each wing clipped. The wingspan is now 74” (1.88 m) from 78” (1.98 m) (recommended by Ken Hirose). This one modification is the reason for the flight test.

3. The reason for this modification is to improve snapping and spinning, as with the 78” span wing, there was a reluctance to spin and tendency to “over snap”.

4. The test flight would be conducted at the Cattle Creek flying field on 27 May, 2006. Test pilot would be Alex Vergara and Obi Mapua. Albert Roa , scheduled test pilot, was unavailable due to a family emergency. The weather was hot and extremely humid (90F) with the sky in a strong gray haze. There was very little to no wind at all. Take-offs were left to right.

5. First test pilot was Obi Mapua. Immediately after takeoff some slight down trim was noted. Two clicks on up elevator (pitch) trim cured the situation. The Paradigm was put through stall turns, slow roll, and avalanches. The verticals showed a slight tendency to go left. The stalls were clean, although the rudder had to be applied precisely or the model would “flop”. It seemed that “flopping” is stall turns was more prevalent now. The slow rolls were very easy to do and relatively straight and could be performed well even at lower speeds. Spins were much easier to enter and needed very little to no aileron input. Avalanches were very good to execute as the model would stop the snap at the right position and attitude. Some power would be needed after the snap to prevent the model from dropping straight down. The down-lines of this Paradigm are quite fast. Landing was smooth and easy.

6. Second test pilot was Alex Vergara. He made two flights with the Paradigm. Various maneuvers from the Masters and FAI-F3A-P07 schedules were executed. Alex remarked that the model has an abundance of power and the vertical are long, there is a slight but marked, torque pull to the left. He would constantly add right rudder every time he added full power. He also noted that the elevators were quite powerful and this made the model quite pitch sensitive. In the point rolls, he liked the precision of the model. The model showed very sharp “pointing” in the point-rolls. Alex also remarked about the way the model stopped abruptly in snapping and spinning. There was no tendency to over or under snap/spin. The Paradigm could be flown either in a “fast” or “slow” style, depending upon the preference of the flyer. Obi likes to fly slow, Alex has a faster style of flying. Alex flew his maneuver much larger similar to Ken Hirose’s execution some of the P07 schedule. Alex commented that the Paradigm was capable but needed more right thrust on the engine. He also commented that the model was fast, or tended to accelerate, on the down lines. Landing was smooth and predictable precise. (Note: Albert set up on the transmitter- JR PCM 9 channel idle-up, engine kill and “spoileron” landing). “Spoilerons” are when both ailerons move up. There will be a marked pitch-up, so this is coupled with some down trim on the elevator. Obi tried one landing on the spoileron and found this made the easy landing easier.

7.Alex and Obi flew the Paradigm two times each.

8. Recommendations:
a. Needs more right thrust on engine. This will cure the tendency of the model to drift left in up-verticals.

b. Thicker tail surfaces. This will dampen the sensitivity of the elevators in pitching, and the rudder sensitivity in knife-edge. The “flat plate” stabilizer, elevator, fin and rudder also do not drag the model enough to slow it down in the down-lines. (A thicker set of tail surfaces will slow it down slightly, but perhaps not as much as the engine braking of a four-stroke engine) At present the tail surfaces are only 3/8” thick. These need to be “airfoiled”.

9. A new design, the Paradigm 2, is on the drawing board (actually in my computer’s CAD program). It has several new features, to enable it to fly the new aerobatic pattern schedules. The new features are: double tapered wing, wider fuselage, pipe tunnel in fuse, taller fuse, airfoiled tail surfaces, and smaller fin. Attached is the 3-view drawing. Note that the wingspan of the Paradigm 2 is at 75 in. This will be reduced to 74 in.