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Archive for May, 2018
Posted by CorvetteC5 | May 31, 2018 @ 12:40 PM | 2,693 Views
Encouraged by the success of my 1-cell Twirl Tiny gyrocopter, and disappointed in the high loads placed on the motor and battery, I rescaled the Twirl plans by Al Foot and created a 2-cell version. It is still small enough, slow enough, and controllable enough to be pilot friendly during indoor RC flying. I deviated from the design of the Twirl a bit more this time around and didn't follow the geometries quite as closely. An advantage to this was the easier adaptation of my carbon fiber framework. As with my smaller Twirl Tiny, the Twirl Tween has a structural frame with a cosmedic profile fuselage and lightly load-bearing wing.

Originally scaled for a 20 inch rotor-to-rotor span, I left the carbon fiber wing spars long and went with it so the actual span is about 22 inches. Motor is a Turnigy 1811-2900 KV brushless, Lipo is a Nano-Tech 260mah 2-cell, ESC is a Castle Creations 6A, RX is an OrangeRX with Stabilizer, servos are analog 2.2 gram from Hobby King, wheels are by GWS. Weight is 64 grams without battery.

My Twirl Tween was unable to rise off the ground due to the stubby landing gear height. So I hand launched the first flight indoors during January 2018 with very encouraging results! Subsequent flights had me move the CG more-and-more toward the tail allowing for higher alpha and slower air speed. I also increased the right thrust of the motor another degree to compensate for the torque roll while in higher alpha flight. Thrust is not lacking from the GWS5030 propeller with easy vertical climbs and hovering. It is rather cool to see the rotor blades nearly stationary during a hover, only to accelerate again when moving forward.

- Curt
Posted by CorvetteC5 | May 31, 2018 @ 11:42 AM | 2,702 Views
This is my Twirl Tiny 1-cell twin gyrocopter that borrowed heavily from the great Twirl autogyro design by Al Foot. I scaled down his plans to 33.8% for a rotor-to-rotor span of about 10 inches, and adapted a frame work of carbon fiber to his geometries. After adjustments and alternations over several months the power is provided by a 7mm coreless motor with 4:1 ratio gearbox, 4 inch propeller, and a 130-140mah lipo. Weight RTF is 23 grams with a Spektrum Mini-Vapor circuit board for control.

For the first flight, I had installed a 8.5mm motor and gearbox but found thrust excessive and marginally stable. Below is what I wrote on March 29, 2016 to a friend who owns the Twirl:

"Flew the Twirl Tiny this afternoon for the first time in Mom's backyard. Close to dead calm air, but not quite. Took several attempts to obtain stable flight. I added about 25% of the available left rudder trim to counter the right thrust. Plus around 5-6 clicks of up elevator, and moving the lipo fully toward the tail to counter the shallow nose dive. Once flying straight and level the Twirl Tiny is responsive to the tail surfaces. Turning well to the left and right, more or less equally. Throttle needed was only about 45-47%, but even so it was fast. Too fast to be indoor flying friendly. Fun and encouraging!

A strange behavior occurred three times. The aircraft nosed upwards and the rotors slowed until the fuselage was hanging vertically underneath the propeller, and the tail...Continue Reading