KIT REVIEW: Ultrafly Ultimate- An Electric Scale Aerobatic Biplane by Bob Murray
Just when you thought the art of model building was dying in this day with the advent of the ARFs along comes the Ultrafly Ultimate. Whilst it is not of the balsa and plywood school, there is sufficient building to allow you the satisfaction of saying “I built it.” Ultrafly describe the Ultimate as an ARF however I feel that stretches the ARF definition just a little.
After talking to the electric flight gurus at Model Flight, I chose to use an E-Flite Park 480 brushless motor controlled by the new Ultrafly Apollo 25 programmable speed controller. The gurus further suggested I should use a Dualsky 2250 x 3cell 11.1volt X-power LiPo.
The E-Flite Park 480 is an out-runner, that is, the magnets are fitted inside an external rotating drum and the wound field coils are inside on the stator, as opposed to the in-runner (for want a better term), where the coils are inside a stationary housing and the magnets are on a rotor inside the ring of magnets. The principal advantage is the result of the interface between the magnets and the field coils having a greater radius on an out-runner. This configuration produce more torque, hence they can normally be used without a gearbox.
For control I chose to fit the exciting new Spektrum DX6 2.4g radio, with 4 of the new E-Flite 75 micro servos. This radio now has MAAA approval.
The Ultimate is a scale model of a full size aerobatic biplane. Ultimate was a company that started out manufacturing wings to upgrade the Pitts specials that have been around the aerobatic scene forever, or so it seems. They then went on to complete the job by building the fuselage, completing the Ultimate.
Opening the colourfully decorated box reveals a collection of moulded foam components and some sheets of die-cut depron that are the horizontal and vertical stabilizers, and their control surfaces as well as the interplane struts. Also included are a number of large sheets of coloured decorative decals, a pre-bent wire under carriage and even a pair of moulded wheel spats, the instruction suggest leaving then off for rough field use there also a tail wheel and wire as well as a tinted canopy.
While Ultrafly supply a 30ml bottle Speed Lock foam safe glue it is left to you to source some 5-minute epoxy and some CA.
The instructions call for small selection of tools such as a sharp knife, scissors, a small drill, screwdriver, pliers and a soldering iron.
All of the moulded parts like the fuselage halves and both wings are moulded in a fine textured styrene and have a very clean smooth surface, requiring only a light touch with very fine sandpaper to prepare it for the decals or painting your own custom livery.
Both wings have grooves moulded into the lower surface for the fiberglass reinforcing rods. I find it interesting that the designers have chosen to use fiberglass for the wing reinforcement but chose carbon fibre for the cabane and interplane strut reinforcement.
Both materials would have been chosen because of its particular stiffness or flexibility to suit its application. Both wing mouldings come with the ailerons still attached that you have to cut off and sand hinging clearance, the ailerons are then hinged with some the clear pieces from the decal sheets.
The E-Flite 75 wing servos were a perfect fit into the cavities moulded into the lower wing and fuselage halves, secured by the Speed Lock foam safe glue. The illustrations in the instructions appear to show some adhesive tape wrapped around the servos prior to gluing, that would be a good idea, to prevent the glue from seeping into the servos before it sets, the tape would be also be easier to remove than the glue for later use of the servo. After hinging the ailerons but before the final assembly, I applied all the decals but for the small one that goes onto the front of the fuselage, which could only be applied after the fuselage was joined.
Decal application; a word of warning. Identify all of the decal locations, relative to their positioning on the upper or lower wing surface. I did not, and suffered the consequences. I placed the lower wing’s parallel blue leading edge decals on the upper surface. However only the sharpest eye will detect such a blue in the finished product. The quality of the decals is first class making the application simple and blemish free.
The instructions suggest, without saying so, that the servos should be installed after joining of the two fuselage halves, my aging digits have difficulty working in such confined places. I could find no reason why they should not be installed before bringing the fuselage halves together.
I actually installed the Park 480 motor and all radio gear prior to gluing the fuselage halves together, (see photo) which also included the rudder and elevator pushrods.
The battery is secured by some Velcro attached to the bottom of the battery cavity, this made installation and removal a little difficult until I hit upon the idea of using a piece of plastic card as a separator for the Velcro. (See Photo)
The Apollo 25 amp programmable speed controller enables you to set brake to “off” for applications such as the Ultrafly Ultimate, but you can engage the brake to ensure folding props will fold in a glider application.
The low voltage cut off can be set for either NiCad / Nickel Metal Hydride or for LiPo’s. Unlike the nickel based batteries, that can be totally flattened and then can be recharged without any problems, LiPo’s on the other hand will be damaged if allowed to discharge too far (below 3volt per cell). The Apollo will automatically sense the number of LiPo cells and cut off power to the motor before the Lipos will be damaged.
I chose not to install a receiver switch, enforcing the disconnection of the LiPo, as a further safeguard against inadvertently damaging the LiPo.,
Brushless motors can often benefit from a little timing tuning and the programming card allows four settings: Auto, Low, Standard and High. For the initial flights I chose Auto, and will experiment with the timing adjustments later.
Flying: Balanced as per instructions 100mm back from the leading edge of the upper wing. I would describe the Ultimate as being very neutral, it goes where you point it. The control throws as per the instructions are set up for hovering and 3D type manoeuvres. My personal taste is for something a little softer and I reduced the throws accordingly. The Ultimate rolls very axially requiring just a tad of top rudder at the knife edges and only a small amount of down elevator whilst inverted. Spins can be induced with just elevator and rudder, and recovery is almost immediate on release of the controls. Using an APC 11 x 4.7 Slo Fly prop the Ultimate hovers very easily and provides flight times in excess of 15 minutes. Flying weight with the 3S2250 Dualsky LiPo is 720 gm.
Bob Murray
"Thanks for the GREAT review.... Mike"
I
want a quote on how much freight it will cost to send items to me.
