PRO-BUILT RIOT

Frank Skilbeck assembles the built-up balsa version of Max-Thrust’s popular high wing sports model

The original foam Max-Thrust Riot has proved to be very successful, with several original and updated V2 versions in our club. Plus, I had the XL version for a couple of years until a club mate persuaded me to pass it on, where it is still doing sterling service. So, the new balsa/ply Pro-Built versions now being distributed by Century UK have a fine pedigree.

Over the last couple of years, I have been drawn back to glow motors and I was looking for a home for an elderly OS 40 FSR. So, when this kit came up for review, I didn’t step back.

The balsa/ply Pro-Built Riot is part of Century’s range of ARTFs for either IC or electric power, comprising the Riot, the low wing Ruckus, the Double Trouble biplane and a Trainer. All are available ready covered or as a bare airframe for the user to cover. The Pro-Built range come with the parts required for you to either complete the model for IC or electric power.

COMPREHENSIVE

The Riot comes well packed in a fairly plain box, with just a sticker on the end to identify the model contained within. The review model was from the first batch and since then they have been rebranded from Pro-Build to Pro-Built to reflect the high degree of completion. First inspection showed a high standard of construction and a well applied covering. Although the Riot is available in a blue, red or yellow cover scheme, the wings and fuselage are all white, with only the rudder coloured, the appropriate decals providing the bulk of the colour scheme.

As well as the main fuselage, wings and tail, a full accessory pack is supplied, along with both an IC engine mount, fuel tank, electric motor adapter and a removable tray with hook & loop straps for securing either the supplied fuel tank or your chosen LiPo. The builder has to provide the servos and radio gear, a 40 – 46 sized glow motor and fuel tubing for the IC version, or a brushless motor and ESC for the magic smoke version. An Overlander 4250/06 800kV, 60-amp motor with a 4 cell 2600 mAh LiPo is the recommended set up for this option.

As noted earlier the review model was to be powered by an OS 40 glow motor but if using an electric motor, a well-designed ply electric motor adapter is provided, with a sliding engine bulkhead to accept motors of different length. The adapter then bolts onto the captive nuts, which are also used for the IC version engine mount. So, you could, if you wish, first fly it as electric and at a later date change things to fit an IC motor, noting that for the IC version the cowl has to be trimmed for the exhaust, needle valve and cooling air.

ASSEMBLY

Mention must go to the very well written and illustrated manual, with many useful building tips. No Chinglish here, so full marks.

Following the instructions, the first thing is to install the engine. This is a good suggestion as if done last the tailplane can get knocked as you move the fuselage around, especially if you have cramped working space. The engine mount is a two-piece design, which allows for different crankcase widths. A neat touch is the hole drilled though the mount for the throttle operating rod. 3mm cap screws and locking nuts are provided to secure the engine to the mount.

Next job was to apply the coloured decals before any more assembly. I must admit this is never one of my favourite jobs and while I did find it possible to reposition the decals if they had not been fully pressed into place, the static charge tended to attract the covering onto the surface and meant I had to lift it off and reposition it a few times. So, some care needs to be taken here to avoid tearing the decals.

The two-piece undercarriage simply bolts to the preinstalled captive nuts on what looks like a pretty substantial ply mount. The axles are bolted to the metal undercarriage legs and the wheels are held on with collects. On the review model the wheels caught slightly on the threaded axle run outs so rather than drill out the wheels I used a couple of electric propeller hub adaptors to act as spacers to ensure free running of the wheels.

The elevator, rudder and throttle (IC version) servos are then fitted and cut outs are provided for standard size servos. An adapter plate, with cut outs for smaller 9-gram servos, is provided, but for this review Century UK provided some Powertech 17-gram servos. This required the apertures in the adaptor plate to be opened out slightly, a simple five-minute job with a PermaGrit file.

TAIL

The tail surfaces are then glued into position. Epoxy is recommended and for this some of the covering film must be removed; as noted in the manual some care is needed here to avoid deep scores in the underlying wood, which would weaken the structure.

Before fitting the control surfaces, I took the opportunity to fit the control horns as this is easier than when they are on the model. The elevator and rudder control surfaces are attached using standard furry type hinges, using thin cyano. The elevators were fitted along with the pre-bent joiner, before the rudder and tail wheel assembly. The steerable tail wheel is supported by a robust metal plate screwed to the fuselage using a collet to support the weight – simple and effective.

The wire control rods to the elevator and rudder are ready sized, with Z bends at the servo and a threaded clevis at the control surface. They all run through pre-installed tubes, which not only provide support but also make installation a doddle. A similar rod is also used to operate the throttle, using a Z bend at the carburettor and a screw connector on the servo.

The cowl for the engine needs to be trimmed for the exhaust and then fitted. I found that with the OS 40 FSR the cowl did not overlap the fuselage very far and I had drilled the holes for the retaining screws too far from the edge of the cowl to get sufficient purchase into the fuselage sides. A couple of hardwood strips on the engine bulkhead saved me from having to redrill the holes in the cowl.

WINGS

With the fuselage just about complete it was onto the wings. Here there is very little to do – fit the aileron servos, hinge the controls and hook them up.

The servo covers are sized for 9-gram servos but have a partial perforation to allow for standard sized servos. Again, as I was using Century UK Powertech 17g servos a few minutes work with a file opened up the mount sufficiently. Draw strings are provided to pull the servo cables through. Usefully, the Powertech servos can be ordered with 200 or 450mm leads and with the longer leads no extension cables are required.

The wings join together using a strong aluminium tube, with a wood alignment dowl, and are kept together with locating tabs on the leading edge and twin retaining bolts at the rear. This enables the wings to be easily separated for transport and installation could not be easier as the supplied retaining bolts are designed to be finger tightened so no tools are required to put the model together at the field.

RADIO INSTALLATION

Century UK also kindly provided one of the Microzone 10 channel, 2.4 GHz transmitters and matching eight channel receivers that they are distributing, and these were used to test the Riot

Thoughtfully, a shelf is provided just in front of the servos and above the fuel tank and this is an ideal position for the receiver. On the electric version it is okay to just to fix the receiver with hook and loop tape, but for IC models I prefer to mount the receiver in foam to isolate it from any vibration.

For the receiver battery I used a four cell AA NiMH pack, wrapped in foam and installed just under the fuel tank. A slot in the fuselage, just under the wing is provided for the receiver switch. Note that there is a slot on each side of the fuselage, and it is best to use the one opposite the exhaust to keep it away from any oily residue.

Pleasingly, the model balanced right in the middle of the recommended Centre of Gravity range, with no need to add any additional ballast – a testament to good design.

For the initial flights I dialled in the recommend starting control movements on the low-rate setting, with around 50% more for the high-rate setting.

UP & AWAY

After a lengthy wait for the lifting of the Covid restrictions it was off to the field. My first visit was not very successful as the old engine was proving reluctant to co-operate. As a precaution I fitted an old spinner to save the new one from any starter damage and this can be seen in some of the photos.

After taking the model home and giving the carb a thorough strip down and clean the engine was back on song and on its second trip to the field the Riot was ready for its maiden flight. The model was lined up into wind, the throttle opened and the ensuing take-off was a smooth affair – it is a Riot, after all!

Just a couple of clicks of trim and the Riot was grooving around, the suggested starting control throws proving ideal for a smooth but responsive model. All normal aerobatics are easy; rolls are quite axial, stall turns effortless and loops on the OS40 are as big as you like. Inverted just needs a touch of down and spins need the model to be almost stopped in the air and rudder to get it to drop a wing
Knife edge wasn’t quite as easy as the model pulled to the wing and needed some down elevator held in. Luckily some ‘Revo Mix’ can be dialled in on the MC-10 Tx to balance the controls.

As the engine wasn’t fully dialled in it was running at a slightly fast idle and this made landing a long affair. Later flights, with a slower idle, have enabled the model to be slowed down more for landing, but this is probably the biggest difference between the IC and the electric (and foamy) versions, where the windmilling propeller provides more drag, slowing the model up quicker.

SUMMARY

The balsa Pro-Built Riot provided no nasty surprises and despite being some 60% heavier than the foam Riot it proved every bit as easy to fly. The model has lots of neat touches that show a lot of thought has gone into the design. Overall construction is very good, as are the supplied accessories.

For a pilot looking to move on from a trainer or a foamy the Pro-Built Riot is a great stepping-stone to flying a slightly heavier and slippier model. It is perfect for practising and obtaining a BMFA ‘B’ certificate, or just a great everyday model for an experienced flier.

Mine has now completed around 15 flights and it has been flown in winds over 15 mph, with the OS 40 FSR proving to have more than adequate power. A 46 maybe a bit OTT and I reckon that the Riot would fly well on a 32.

So, in summary, it’s well designed and built, easy to assemble, easily transported and great fun to fly. What’s not to like?

DATAFILE

Name: Pro-Built Riot
Model Type: High wing sport
Manufactured by: Max-Thrust
Distributed by: Century UK (www.centuryuk.com)
RRP: Check website
Wingspan: 1380mm (54.33″)
Length: 1160mm (45.7″)
IC Power: 40/46 two stroke glow
Electric Power: 4250 800 kv motor, 60A ESC, 2600-3300 4S LiPo
Flying Weight: EP – 2.25 kg, IC – 2.23 kg (as reviewed)
Functions: Throttle, Rudder, Ailerons & Elevators