The wings and tail section are glued in place (above left) and “eyeballed” into proper alignment. Pins through the root ribs hold the wing alignment, and glue bottles hold the tips at their proper dihedral angle while the glue sets up. The nose block (above right) is made from ¼-inch thick balsa with a brass tube bushing and a macramé bead for a thrust bearing. Simplicity is the order of the
day for the Flummox. The completed airframe (below left) requires only the addition of the rubber peg and she’s ready to fly. The model balanced almost perfectly without rubber, so the motor peg was located equidistant from the c.g. as the prop hook to maintain balance without added ballast. A small plywood disc (below right) is used to reinforce the fuselage at the rear motor peg.
Day 2
With the airframe basically finished, the only thing left to do was to build the nose block. The block was cut from 1⁄4-inch balsa and the front and rear sections glued togeth- er and sanded to shape. The block was set up and drilled for the right thrust and the brass tube prop shaft bushing glued in place. The prop hook was bent from .032-inch steel wire and the prop secured with a 90-degree bend so the prop would freewheel. And finally, the fuselage sides were reinforced with 1⁄64-inch ply discs and drilled for the 1⁄8-inch alu- minum dowel motor peg. All said and done, the airframe weighed in at 17.1 grams with- out rubber.
Test flights
Without rubber, and with the nose block in place, the c.g. looked pretty good, and af- ter a couple of test glides appeared to be a good starting point. In the meantime, the rain was finally letting up, so I figured the time was right for a few trim flights. A 15-inch and a 20-inch loop of 3⁄16 Tan rub-
ber were made up for the initial test flights. Originally the nose block was set up with 21⁄2 degrees down, and 2 degrees of right thrust. Both proved to be too much, so shims were placed under the nose block to make the nec- essary adjustments up and left.
FLYING MODELS
The model also had a tendency to “death spiral” under power, so the vertical tail was trimmed down as well. It was finally deter- mined that the 15-inch loop was too short and the excess power was unmanageable over about 400 turns. By going to the 20- inch loop things settled down nicely and be- gan delivering flights in the 30–40 second range on 750–800 turns.
Above 800 turns on the 20-inch loop, the model wasn’t happy either and became very sensitive to trim. But being in the relatively small park, going to a longer loop and more turns didn’t seem like a wise move, especial- ly since I had already gone wading in the ar- royo to retrieve the model from an excep- tionally good flight once already. Besides, the breeze was coming up and the rain was starting to fall once again, so I considered the day and the model to be a grand success, packed it up, and headed for home. In the end, the model ended up with no down, and about 1 degree of right thrust. A very small dab of tail weight was needed, and about 3⁄4 inch was removed from the top of the vertical tail to tame the initial death spiral. The model naturally leaned toward a right hand power flight, and by adding just a little washout to the left wing was able to open up the circle for a very nice gentle climb and subsequent glide back down.
So, if it’s a quick building fun flying sim-
ple little sport model that turns your crank, this might be just what the doctor ordered. Chances are you’ll never win a contest with it, but for good old fashioned no pressure flying just for the pure fun of it on relative- ly small fields, the Flummox is just the ticket.
Upon re-entry the glide is smooth and level. You probably won’t set any records with the Flummox, but it is a terrific small field flyer.
35
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68