The kit - Assembly - Installation - Flying - Conclusions - Specification
I must admit that I have been eyeing the current breed of ARTF electric assisted gliders with interest for some considerable time. When the opportunity arose out of the blue to review the 'Stratus Sports', I literally jumped at the chance. Such was my enthusiasm that less than a week after saying, "Yes, please", the model was flown for the first time - in pouring rain! Well, there was some boring old festival called 'Crossmass', or something, going on at the time!
There's really not a lot to this. There is a moulded fuselage, which is made from a polythene type of material, a moulded foam three-piece wing with a hard glossy skin, moulded tail surfaces, a 'tree' of plastic parts, a sheet of die-cut ply parts and a bag of fittings which include the motor and a folding propeller. Add to that an instruction leaflet and a large sheet of very nice decals and there you have it.
To complete the model you will need a three channel receiver, two small servos (not necessarily 'mini'), some kind of speed controller (not really necessary), or switcher (necessary). Either of the latter two items should have a BEC (battery eliminator circuit) with low voltage cut-out. Finally, you will need a seven cell battery pack of 1200 to 1700 mAh capacity. and a suitable fast charger.
All of the fittings that are attached to the fuselage are bolted or screwed in position. There are also moulded-in positions for cooling air inlets and outlets. I must admit that I eyed these with some suspicion because they remove material from the fuselage at what appear to be high stress points. The motor is retained by two screws which go through the front of the fuselage into the end of the motor can. A large metal washer on the outside serves to clamp the fuselage material securely. An adapter is then held on to the motor shaft with a grubscrew and the spinner backplate/prop hub is then retained by a nut and washer.
The leading edge of the wing is retained by a single peg, which is actually a piece of aluminium tube. This has to be glued into a wooden block which is already moulded into the wing. A saddle fits inside the front of the wing opening on the fuselage to accommodate the peg. This is retained by two screws. The trailing edge of the wing is held down by two countersunk screws which go down through the wing into another saddle, which is also retained by two screws.
Moulded into the fin/rudder assembly are two wires, with threaded ends, which go down through a moulded plastic saddle, then through the tailplane and fuselage and are retained by two plastic 'nuts'. The rudder and elevator hinges are moulded-in and are rather stiff. You are advised in the instructions to cut away the rudder and re-hinge it using adhesive white strips which are part of the decal set. This works well, but leaves the bottom end of the rudder floating around in the breeze.
The three wing panels are simply epoxied together. At each joint there are three 'Liteply' dihedral braces. The centre section has moulded-in spruce spars, top and bottom, and the braces fit inside them. The tip panels simply have a hole for the braces. Note that the braces are asymmetrical and the longer side goes into the centre section. The braces must be correctly positioned in order for the wing sections to line up properly.
The model is completed by the canopy which consists of inner (black) and outer (clear, tinted) mouldings and a soft plastic head (flesh-coloured). The inner section has two keyhole-shaped holes which engage two screws in the lip of the fuselage cut-out. By squeezing the fuselage, the canopy can be removed. Some careful trimming is required and the eventual fit of the canopy to the fuselage depends on the alignment of the inner and outer halves.
Rudder and elevator have plastic horns which are retained by two screws and a plastic plate. The pushrods are ready-shaped pieces of wire, with a 'Z' bend at the servo end and an adjustable clevis at the horn end.
Two servos are mounted on a ply plate which is screwed to two plastic pillars which are also screwed to the lip of the wing opening. A similar arrangement, with a narrow strip of ply, is also mounted further forward in the wing opening. These two serve as saddles to support a larger piece of ply which then serves as the battery support.
This whole assembly can be fitted, or removed, either collectively or in pieces via the wing opening or the canopy opening. The assembly was not entirely clear from the instructions because the positioning of the support pillars is rather different in the instructions than it is indicated by the 'pips' moulded into the fuselage. The length of the ready-made pushrods is consistent with the position required by the pips. Only after flying the model did I realise that the entire assembly can be moved about to adjust the models CG position (you have to drill new holes for the pillar screws and change the pushrod length too).
The receiver is fitted under the battery platform and there is a limited amount of room available, although all of the current generation of slim receivers should fit. The battery platform also contains a hole for the on/off switch, just under the canopy. However, the thought of an electric aeroplane with an internal switch didn't appeal to me, so I cut a hole in the fuselage instead.
The instructions do suggest the use of a speed controller, but this is really not needed and I used a switcher unit. I was a little worried about the effect of a 'hard' start on the folding prop, but this has not been a problem.
The advised position for the CG is 73 mm behind the leading edge. As built, mine came out substantially ahead of this. However, better nose heavy than tail heavy, so I decided to go ahead and fly, starting with a few test glides.
It needs quite a hefty 'shove', even in a brisk breeze, but the glide is superb, although fast. It helps if you fly 'Mode 1', as you can hold on elevator trim while you launch. Thus encouraged, I gave it another launch and then switched on the motor, which resulted in a surprisingly steep climb (for a 7 x 3 propeller on a two metre span model weighing three pounds). The flight was terminated after about seven minutes - it was raining, remember - and I went home happy to discover that there was still four minutes of power left in the battery.
Further flights confirmed an initial impression that the rudder response was very slow. All flying to date has occurred in very windy, blustery conditions, and an increase in rudder response would certainly help. The flying speed is quite high and the model really scoots around the sky, which helps in turbulence.
With an available motor run of about five minutes, the longest flight to date is around 18 minutes. Remember that this is in January and the model has never been flown in anything approaching calm conditions. I can't wait for those calm summer evenings.
Subsequent flying in better weather revealed that the model was indeed nose heavy, with a sunstantial trim change between power on and power off. Moving the CG back to the advised position made a vast improvement. To acheive this it was necassary to drill new holes for the battery/servo platform and move it back, together with a shortening of the pushrods.
It really likes to move and trimming for the slowest glide does not give the best performance. Letting it fly faster gives a flatter gkide and a lower sink rate.
With a very small amount of effort, you can be the proud owner of a very practical machine with an excellent performance. The glide is fast and very flat, while the motor/propeller combination gives a good rate of climb. The wing alone weighs a mere ten and a half ounces, is superbly moulded and is very efficient.
The rudder response is, perhaps, a little sluggish in turbulent conditions, but is otherwise adequate.
Having accidentally tested the crash resistance of the wing fixing, the aluminium tube retaining dowel bends under load and is easily straightened.
|Wing Span||1920 mm (75.6")|
|Wing Area||36 sq dm (560 sq in)|
|Overall Length||1050 mm (40|
|All-up weight (as tested)||1.36 Kg (48 ounces)|
|Propeller||7" x 3" folding|
|Control requirements||3 channel receiver with two servos, motor on/off switch, or speed controller with BEC|
|Battery||8.4 volt 1200 - 1700 mAh|