At the height of their success in the World Aerobatics Championships, the Russian Sukhoi company launched the SU-26m as a refinement to the already successful SU-26. Sporting a growling radial engine and mid-wing design, the full size SU-26m stood out among its peers as a fast aerobat with a spectacular roll rate, high pitch manoeuvrability and unrivalled vertical penetration. The plane’s superior performance proved good enough to scoop the 1986 World Champs for the Russian Team.
The best scale models preserve at least some flying characteristics of the full size, and it was a pleasant surprise to find this 480 size recreation from Horizon Hobby achieves this. A thin wing profile and deceptively slippery shape mean the model is most at home flying big fast scale-like aeros guaranteed to put a smile on your face. The perfect small model for scale aerobatics then? Well, let’s have a closer look.
The 43” span model is designed around a 3S 2100mAh lipo and 480 size brushless motor. Deciding at an early stage to stick with the stock setup I used all the components recommended in the manual, these being as follows:
• E-flite Park 480 motor, 1020kV
• APC-E 12 x 6 prop
• E-flite 40A lite pro brushless ESC
• 4 x Spektrum S75 micro servos
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My one deviation from the book was to use a 2250mAh 3S Li-Po battery.
Assuming you’ve assembled similar ARTFs before you could almost dispense with the manual, the construction method being almost generic. Here’s why I suggest you follow it though – it makes the whole process so easy. Every step is illustrated and explained in detail and nothing is left ambiguous. An object lesson in how to document a product. Even with a conventional build there are the usual gotchas to watch out for – slicing through the covering prior to gluing the horizontal stab in place is especially perilous given the close proximity of 3/8” thickness of flatplate balsa beneath.
Despite a conventional balsa and liteply construction the major components have an impressive strength to them and my attempts to twist the fuselage while holding the wings produced no noticeable deflection at all. This bodes well for good flying performance and is certainly down to no fewer than 14 longerons running the length of the fuse. A fully sheeted front half to the fuselage adds to the sturdy impression and will hopefully contribute to a higher resistance to future hangar rash.
MISSING PRESUMED EXTRA
A few things you won’t find in the box are wheel spats, a spinner, pilot or dummy radial engine, all of which feature as optional parts available from your local E-flite stockist. With a street price of around £130 it seems a little churlish to charge extra for these items. They’re not pricey in themselves but most hobby shops seem not to stock them so need to order them in.
I can live without a dummy radial but without spinner and spats I reckon the model wouldn’t look half as good.
RUSSIAN TO FINISH
Do remember to leave a 1mm gap when gluing the ailerons and elevator in place. Less than this and you will lack full deflection when trying to set the recommended high rates – not necessarily a drawback if 3D flying isn’t your thing. Do also stick to the recommended maximum deflection on rudder and elevator, these being 50mm each. Allow your radio to command more movement than this and you will find the rudder horn can clash with the elevator trailing edge, which could lead to the elevator becoming locked fully down when rudder is applied. That kind of thing can really spoil your whole day if you discover it for the first time at the bottom of a blender!
Fully assembled and with battery on board, but lacking pilot the model weighed 994g, significantly more than the 850-910g target weight listed in the manual. With the 12 x 6 prop running flat out my wattmeter recorded 26.8A and 315W. That’s more or less 145W/lb, which ought to suffice.
Strangely the E-flite manual omits to mention expo settings but I used 30% on aileron and elevator and none on rudder, which has turned out to be perfect.
I chose an early start to maiden the plane in the calm still air of a fresh summer morning. Accelerating briskly she took her first trip into the air at just over half throttle after a ground run of around 15 feet. No reluctance to aviate there! Once aloft and trimmed there was a distinct lack of precision noted in the control response, a sponginess which failed to inspire confidence. Fine corrections appeared not to take effect followed by a sudden over correction as more stick was applied. The clue to source of my woes came when I found the situation worse at higher airspeeds.
The inescapable conclusion was that the S75 servos were not up to the job. With the model safely back on the ground and some simulated aero loads held against the control surfaces the hypothesis appeared to be proven, as the micro analogue servos made heavy weather of pushing the control surfaces around.
In place of the S75s I have fitted a pair of micro digital servos on ailerons and a Hitec HS-65 on elevator. I can live with a spongy rudder so have left the S75 fitted to that surface. With upgraded servos onboard, maiden mkII was a far more enjoyable experience and finally gave me a chance to evaluate the little Sukhoi’s characteristics.
No real torque swing was observed in the take off run, the wide-spaced undercarriage keeping the brief ground run stable until the point of lift off. With the sticks left alone the model is very stable in straight and level flight, and given a day without turbulence will fly gorgeous straight and true low passes. Any downwards trajectory sees the airspeed build quickly even with modest power applied so heed the warning in the manual and avoid full throttle on downwards runs.
I found the much delayed onset of stall to be a harmless affair, a small nod of the nose and then she’s flying again with no alarming tip stall or similar bad habits. Landing approaches can therefore be approached with confidence but do require around 20% throttle to keep the air flowing over control surfaces.
Although rudder authority is good, in knife-edge flight a fair airspeed is required to allow the inclined fuselage to provide enough lift. A small degree of negative coupling is present and a transmitter mix of rudder to elevator will help your mind concentrate on things other than holding in elevator during knife-edge passes. Slow flight is eminently controllable with plenty of warning before reaching the stall as the controls become progressively less effective.
Once inverted a small push of down elevator is required, confirming my suspicions that there’s scope to move the centre of gravity back. How to achieve this is less clear, since my battery is as far back as possible and I’ve had to add 20g of lead at the tail just to get to the specified C of G position. Either more lead could be added at the tail or I could sacrifice my nice aluminium spinner.
With the stock C of G I found prop hanging difficult to maintain, but not impossible. Harriers exhibit wing rock which can be controlled with the appropriate aileron input but a more rearward weight balance is likely to assist. On high rates, rolls are a blur and snap rolls are, well, snappy sir. Blenders are best not approached too fast as structural loads can soon build up and with a flat plate tailplane only so much can be taken before flutter becomes a risk.
Although park flyer sized the plane can cover ground quickly and needs to be flown in a large open park or proper club field. It’s well mannered but should only be considered by intermediate pilots and above.
The Sukhoi is 3D capable but isn’t optimised for that style of flight and comes into its own when flying big aerobatics in a scale fashion. It would certainly make a good small freestyle plane, happy to blur the boundaries between pattern and 3D flight according to how the mood takes you. Having flown it over the course of several months I’ve found this flexibility to be a positive advantage, often providing a reason for it to be taken to the field in place of another model.
The undercarriage has taken the odd hard knock without the mounting plate coming adrift and that is a rare virtue in this class of model. All in all, despite my reservations regarding price and optional extras, I do think it represents good value. The model has an evident high build quality which should lend it longevity and has a charisma when flying which makes the ownership experience a satisfying one. Most telling of all, it reminds me of the full size.