Mini Firefly
(Online Plans for original size)

29 Dec 11 - Update on problems experienced

Mini Firefly Mini Firefly Mini Firefly Mini Firefly

N° of launches / Time 0 0h 0m
Wingspan 13.5" 342 mm
Wing Area 144 □" 9.3 dmē
Flying Weight 1.21 oz. 34.3g
Wing Loading 1.21 oz. / □' 3.7 g/dmē
Wing Cube Loading 1.2 - Glider (ultralight at that)
Motor HobbyKing Micro Power brushless system with Gearbox (GPS-C03)
Propeller GWS DD 5" x 3" (EP-0503)
Batteries 1S1P Li-Po 120mAh to 160mAh
Speed Controller XP-3A Brushless Speed Controller - 3A - 1S LiPo
Receiver Spektrum AR6300 - 6ch (micro-connector) - 2.4GHz - 1S LiPo only
Servos Elevons - 2 x HK-282A Single-Screw - 2g - 2 Nm - 0.08s
Static Performance Not testable as yet
Flight Performance Not yet flown

29 Dec 11 - Some time ago I went to fly this and during the pre-flight check the elevons deflected proportionally to the throttle setting, and tried several batteries; on returning home I tried it again with the same results.  A few weeks ago I tried again and the effect seemed to have disappeared, only to return when a different pack was tried.  I determined that the effect must be voltage related as it only occurred with smaller (120mAh) packs and never with larger ones  (150mAh - 180mAh).  I need to make a testing rig so I can find out what current is being drawn by the motor.

2 Jun 11 - A friend sent me link to the Firefly thread on RC Groups.  The original Firefly is a 24"  span EPP model which uses a Kline Fogleman section.  I decided that a smaller version would be interesting for indoor flying and I could use the micro-geared brushless set-up sat around idle.  The Kline Fogleman section is basically a stepped section with a strip under the leading edge for approx 35% of the chord.  The model was scaled to match the propeller size the motor wanted, which resulted in a 13.5" (342mm) span.  The model was assembled from 3mm Depron with the lower mainplane piece and rear of the fin cut from a black sheet for contrast.  I was originally going to build it using a UHF RX but swapped to the AR6300 which was also spare.  The speed controller is an amazing little device and rated at 3A, far more than the battery can deliver.  I originally fitted 3g servos, but one failed during set-up so they were removed and replaced with some 2g servos.  When using a 160mA LiPo it balances without ballast, but a 6mm washer is required for smaller cells.

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