Another one of the attempted whirligigs. In this case there was a 4 bladed propeller which came off the first whirligig attempt (still to be video'd). The machine almost worked in windy conditions, but needed slightly more power, so I made a 5 bladed propeller with a slightly larger diameter. Therefore the spare prop. The previous attempts using the 3-bladed and 6-bladed propellers didn't even seem close to working due to the unbalanced weight of mainly the wings. The obvious solution seemed to be select a design which had balanced wings, which in this case resulted in a biplane configuration.
View of the 4-bladed propeller and almost balanced wings.
The biplane layout deviates a little from the classical formats in that the upper wings are supported by what looks a little like the base of an inverted Vought Corsair wing, which adds a classical fighter but not biplane look to the aircraft (not realized during construction, but only during blogging). Construction of the wing supports was difficult, as it was narrow, and I didn't want to do a square woven mesh as used in the older monsters. To overcome this it is covered with a 0.9mm wire diamond mesh connected with jewelry sourced crimp ferrules.
The pilot has been given a classic cockpit windscreen and headrest fairing to improve the looks. To keep the structure rigid the cockpit supports were joined with ferrules which were crimped and soldered. The technique works well enough to use whenever a structure is not firm enough using crimped wires only. The pilots neck was meshed using the old weaving technique ... still has its place. And the standard crab claw head had to make it's appearance.
To enable the propeller to turn quickly while still having a reasonable wing flapping rate a planetary gear set was printed for the front-end. This is the same thingiverse sourced, print in one go, herring bone, planetary gearbox as used in my previous whirligig attempts. To mount the gear set a tin ring was constructed with silver soldered attachment points for wire supports. The wire supports were twisted to represent cylinder heads similar to what would be found in a radial engine. These are attached to the fuselage. The springs (cylinders) can easily be adjusted to allow the 'radial engine' to be centered. The propeller is attached to the gearbox via a universal joint. This was required to allow for some de-centering as would be expected with a wire construction.
The back of the planetary gearbox has a bent wire with two cranks to flap the wings and pilots head when the propeller is turned. The mechanism is relatively simple with the wings flapping in the opposite direction. This is done so that when gravity acts on the top wing, it assists the bottom wing to fight gravity, and visa versa. The pilot head has a lead weight added to try and achieve a neutral balance. This was done in an attempt to get the mechanism smooth enough to be wind powered.
Unfortunately friction, inertia and the difficulty to get the wire bits well centered seems to result in too great demands in the power department. That combined with living in an area where wind is not all that plentiful means that I cannot confirm that it is a whirligig. This is why all the video shots show it turning with external power.
To complete the monster it was covered in silk and varnished until it looks like old skin. The acrylic detailing in a predominantly blue colour scheme was added and varnished with a hard glossy artist varnish to protect the finish. Cast lead wheels were added to match those of the other whirligigs so that it could look like a series. The normal warnings about sucking the wheels apply, even though there is the acrylic detailing and varnish finish.
The birds eye view of the monster is added to show the swept back effect of the wings and the overall rounded bat like curves. Real planes don't generally have wings which are as swept back as these monsters, but it does look more like one would expect from a natural flying object. Wonder if there was ever a bird with four wings? Guess not.
