The Swap Meet Gemini Biplane
Rebuilt, Right, for More Use
Until the Foam Gave Out
By Carl Murphy
Complete Airplane as Received
Start of July 2017 The tail surfaces have warped so bad as to be useless. I’ve had hundreds of foam airplanes, I’ve never seen anything like this. The original tail was cut off, a start of patching on a used Fun Cub tail was begun. This foam was too old to justify the effort expended.
The (miss) Adventure Begins
With a budget in the hundred dollars for new outlay range (I have some stuff already) a used, complete, Multiplex Gemini (evidently ready to fly, just needed a battery) changed hands for three Andrew Jacksons the second week of March year 2017.
Despite flying RC in San Diego County (CA) since 1995 I’d never been to the Weed Whackers flying field in Lakeside CA (once country, now metropolitan San Diego County) and felt the need for a new project, without actually spending much. My previous attempt at a general purpose RC airplane for use the weeks and months on end in my camper, bought on a whim as Hobby People went out of business (The DT-760) is chronicled in a previous SEFSD article. I threw the DT-760 out, every bit of it. I did learn though, from other SEFSD club members, that the little connectors for power it came with were undersized, cutting back the performance by a fifth or more. I paid the Editor (club members for twenty years us) off in lobster recently.
From watching others fly, this improperly set up foamie is the rule, not the exception. This used Gemini must have flown (sort of) but, as purchased it must have flown poorly.
Follow along, in story form as the mistakes are corrected (the original motor thrown out, servo linkage so tight it wrecked a servo, replace both (poorly mounted) wing servos, improvements made, reinforce the whole airframe (making it a Reinforced-Gemini) motor testing with different batteries and motor controllers etc. Different than a vast majority of what is in print, the outcome is not pre-assumed to be “everything went great on the first try” as a used, complete, known by type from hundreds of personal flights with having owned and flow four of this type, fun to fly RC Biplane in impact resisting foam with electric propulsion, is reworked by an almost, but not quite, broke, new owner.
But I’m warning ya, I can make a fool out of better financed RC pilots with my stuff.
By Robert Stinson
You may have seen this flying at the SEFSD field and wondered what it was. Is it a real plane, did it really have a third motor on the tail? The answer to both questions is yes! The plane is the Canadair CL-84 Dynavert, developed for the Canadian Armed Forces in 1964. Four were built, two still exist in museums. In an age before “fly by wire” electronics, the design was truly visionary. Top speed was 321mph, certainly faster than the helicopters of its time. However, its uniqueness and the rapid pace of helicopter development kept it from being adopted operationally.
The model has two modes, hover and forward flight, both controlled by an onboard computer. In hover, the two main motors provide lift and roll control while the tail motor, which rotates left and right, provides pitch and yaw control. Stability in transition to forward flight is handled by the computer. A big servo in the fuselage pivots the wing. In forward flight, the tail motor shuts down and control is by standard elevator, ailerons and rudder. The real plane did not tilt the tail motor, but achieved hover control via variable pitch propellers, and flaps and ailerons in the main propwash.
The Dynavert model sometimes gets mistaken for a V-22 Osprey, but the Dynavert preceded the Osprey by 40 years. One main difference is the CL-84 tilted the whole wing, while the Osprey only tilts the motor nacelles. This latter is a distinct advantage, as when the Dynavert wing is vertical it makes a great air dam! If the model is flown in a breeze, it sometimes has to tilt close to 45 degrees simply to keep stationary.
An example of the real one is on display at the Canada Aviation Museum in Ottowa.
By Jeff Struthers
This has been a fun project, giving a new “Lease on Life” to an old airplane.
The aircraft in question is a Multiplex Sonic Liner and was only available years ago. I liked the look of it then, but as I was just starting out in R.C. Flight, I knew I would crash it. Eventually Multiplex took the aircraft out of production. Bob Stinson and I think this was around 2007.
I pretty much forgot about this airplane until early this year, when I was in Discount Hobby. I decided to walk back where the new boxed aircraft were to see what was there and wow, here was a Multiplex Sonic Liner. Still in the box, with a $ 46.00 price tag on it!
We have all felt the rush of finding a cool aircraft that fits within our budget, but how about for $46.00? Way cool. So, box in hand, I found the store owner John and asked about this. He said a customer had it sitting around for years, unbuilt and it was missing the battery / upper hatch cover. The cheap price was reflective of the missing part which John and I both thought could be made from Home Depot styrene insulation foam.