Gemini is the first Elapor biplane from Multiplex and has been designed as an easy introduction to two wings. Since the model is called Gemini I can only assume that the link with the star sign (the twins) is the fact that it has two wings? Anyway, whatever it is that’s in the name there’s no denying it’s a good looking little model that appears to take a few design cues from the Ultimate biplane, which to my mind is no bad thing.
Moulded around an outrunner motor of the 600 class, with power from a modest 3s 1800 – 3300mAh Li-Po battery pack, the Gemini should be a relatively inexpensive proposition. You’ll forgive me for the following cliché, but when the box lid is opened one is presented with an Elapor foam model of exquisite quality. The box itself hosts a perfectly moulded polystyrene foam cradle so all the parts are placed in their own bespoke moulded slots for transport. Truth is, the cradle looks as if it took almost as long to design as the model.
Instruction wise, the manual, in typical Multiplex fashion is very precise and very well written, whilst complemented by black and white photos and drawings to guide the builder. Meanwhile the assembly process itself is very straightforward. I’m always highly impressed with the fit of the parts in a Multiplex kit; they certainly seem to produce some of the most accurately moulded foam components you’ll come across and building the Gemini has done nothing to dispel the notion.
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Based on my past experience with Elapor models, I chose to use a thick cyano’ glue with an activator spray to hold everything together, as although Multiplex suggest the use of medium-thick cyano’, the thick stuff allows a little more time to position parts before the activator bites. The method here is to spray activator onto one of the gluing surfaces, allow it to dry and then put the cyano’ onto the other surface before bringing the parts together.
The process of assembly simply comprises the two main fuselage stages, followed by the wings, with radio installation and decal application following on. The manual suggests that the elevator and rudder servos be installed before joining the fuselage sides together, although since I was undecided as to what servos to fit, I elected to build the fuselage and install them later. This made the task a little more fiddly but by no means difficult as the fuselage has acres of space inside to move the cables around and fit the gear.
For those with a really tiny car (or a motorbike!) the Gemini features an optional wing removal system that, although typically clever, I’ve not had any need to use. At just 36” span the model fits in the car fully assembled with bags of room to spare.
WINGS
Make sure you apply the top and bottom wing decals before you get the cyano’ out, as it’ll be a nightmare to try and apply them afterwards. The underside of the lower wing, of course, can wait until the servos are installed. Follow the manual to the letter here for it’s important to put the wing components in the right place as some of the parts are ‘handed’. Our first task here, then, is to assemble the centre cabane structure. This is a bit fiddly, but follow the manual and everything should fall into place. The remainder of the wing assembly is a breeze but I’d suggest you dry fit everything just once before you get the glue flowing – mistakes are easy to make but very difficult to fix once everything is covered in cyano’.
Motor choice could be a little daunting to the electric flight novice, although Multiplex suggest two options from their range so use these as a guide. I wanted a performance motor to pull my Gemini, my choice made easy by a call to RCM Direct, the guys there suggesting one of their own 28/14 6T motors, a speed controller to suit, a 2200mAh 3s Li-Po battery pack and an APC-E 10 x 5 prop.
Servos were a slightly different matter and in this respect I made a quick call to Brian Collins at BRC Hobbies to mull over the options. Between us we decided that a set of JP Titch 50 digital micro servos would work well and at £37.99 for a set of 4 my wallet was happy too! These little servos have a very impressive 1kg torque rating and move 60 degrees in 0.12secs, which is ample for a model such as this. Since the servos are digital, I decided to use one of my JR R700 receivers so as not to leave anything to chance. The R700 is a very capable receiver with no chance of bombing out under the strain of the extra current required by the servos.
With a trip to the field on the cards all I had left to do was apply the remainder of the decals to the airframe. Incidentally, this is by far the most time consuming part of the build but after a few hours the Gemini really starts to look the part. I even fitted the spats – something I normally try to avoid as both of the fields I fly from are grass and smaller models tend to trip-up easily. Having said this I was pleasantly surprised to find that the spats coped well during a quick taxi test on my back lawn. It was also very obvious that there were no shortages in the power department.
UP, UP AND AWAY!
Whilst the Gemini can be hand-launched, I much prefer to see ‘em fly off the deck so I lined her up, applied full power and watched the aeroplane literally leap into the air within 15ft. With the model displaying a stunning climb-out I found myself having to dial in a little down trim to address it, backing the throttle down to half at the same time. No other trim was needed to maintain level flight.
Aileron and rudder response is acceptably positive and throttling back, I detected that the model was very stable at low speed. With this I gained some height to see what the stall was like just in case the Gemini had some surprises in store, but my fear was put to rest when I applied full elevator at a snails pace and held it for a good few seconds before the model gently mushed, dropped a wing to the right and entered a slow downward spiral; she recovered instantly once the sticks were centred.
The lateral stability of the model is superb, indeed the Gemini stays exactly where it’s put with very little if any rudder input required, making four point and hesitation roll’s a breeze. Meanwhile, the rudder itself is powerful enough to allow full knife-edge loops on little more than half throttle.
One aspect I particularly like about this model and the power set-up I’ve used, is the unlimited vertical performance. You can stand the Gemini on its tail from little more than walking pace, then open the tap and watch it climb vertically, as fast as it flies horizontally. At quarter throttle there’s sufficient power to stooge around employing mild aerobatics but open the throttle half way and you can perform continuous loops without losing any height at all. Inverted flight is no problem with a touch of down to hold level and she’ll also bunt without losing height.
Prop-hanging the model couldn’t be easier; even I can do it with the Gemini!
What’s she like in a breeze? Well, she’ll cope okay but like most small electric models this one really comes into its own on calmer days. Whilst the 36” wingspan nods towards a park-suitable airframe, thoughts of flying the model in a small space should be ignored – this is a very capable, fully aerobatic biplane that won’t embarrass a 3D pilot and has a capability for speed that can easily match a .40 size i.c. model.
SHE’S A CRACKER
To be honest I wasn’t too sure about the Gemini when I first saw it, but now, I love it. It’s one of the first models I grab for a quick session at the field. It’s already stretching my skill set and it’s teaching me a few new tricks to boot.
Once again, I think Multiplex have hit the nail on the head with this one, it’s a cracking little model and another clever design that’s been beautifully executed with Teutonic precision. If you fancy a small aerobatic biplane then you need look no further than the Gemini.
RRP's @ June 2013 – £109 (kit), Tuning power set £130.
DATAFILE
Name: Gemini
Aircraft type: Sport aerobatic biplane
Manufactured by: Multiplex
UK distributor: J.Perkins Distribution
Wingspan: 36" (920mm)
Fuselage length: 36" (920mm)
Wing area: 537 sq. in.
All-up weight: 2 lbs (940g)
Wing loading: 9oz / sq. ft.
Rec’d motor: Himax 2816-0890 or 3516-1130 (high performance set-up)
Rec’d ESC: 45amp depending on motor used
Rec’d flight pack: 3s 2100mAh Li-Po
