Roban 700 Size EC-225

Roban 700 Size EC-225

The Eurocopter EC-225 Super Puma, also now known as Airbus Helicopters H225, is the next generation of the famous Puma that has been a mainstay of twin engine long range passenger transport for decades. Powered by two 1,776 kW Turbomeca Makila 2A1 turboshaft engines, it can carry 24 passengers with 2 pilots and a cabin attendant at a cruising speed of 260 km/h with an impressive 857 km range. The big machine is 19.5 m in length with a 16.2 m 5-blade main rotor system and a max. take-off weight of 11,200 kg, with a retractable tricycle undercarriage. The Super Puma received its airworthiness certificate in 2004 and has been sold into some 19 countries in both military and civilian types.

Roban Models’ EC-255 is the 19th model in their 700 size Super Scale range and includes their SM2 mechanics that sit in the scale position under the engine covers. Thus, the entire cabin is open for scale detail and a fully illuminated cockpit is included along with pilots and passenger. Plenty of scale detail is included in the moulds along with add-on aerials, steps and running lights etc. The assembled mechanics are supplied with a 5-blade rotor head, 4-blade tail rotor and retractable undercarriage just like the full size. The model is 1700 mm long with a rotor diameter of 1560 mm, which gives a scale of about 11.5:1. The model is designed to run on 12S LiPo power driving a 450 Kv motor, which both have to be supplied by the builder, along with 3 metal geared servos for the 120º eCCPM swashplate control and a high-powered servo for tail control. The published specifications of the model follow:

Body length: 1680 mm
Width: 415 mm
Height: 510 mm
Main rotor diameter: 1560 mm
Main blade length: 700 mm
Tail rotor diameter: 280 mm
Tail blade length: 105 mm
Main shaft diameter: 12 mm
Tail shaft diameter: 5 mm
Spindle diameter: 8 mm
Battery compartment: 120 x 60 x 180 mm
Motor: * 1 x 750MX 450 KV brushless outrunner 12S capable
Speed controller: * 1 x 120A brushless, 12S capable
Servo: * 3 x metal gear cyclic, 1 x metal gear tail servo
Battery: * 44.4V 5000 mAh 35C
Flight time: +5 minutes
Take off weight: 8500 g
Flight Stabilization: * 3 axis flybarless gyro
Radio Control: * min. 6 channel with pitch and throttle curves
* Optional equipment

The Roban EC-225

Roban have certainly perfected their packaging as all the parts are carefully wrapped with smaller components packed in boxes while the main fuselage mouldings are securely fixed inside the strong cardboard box with the other boxes glued to the sides so nothing will come loose in transit. Then, to be doubly sure, the box is put inside another box. So, yes, the EC-225 arrived without transit damage!

The manual is down loaded from Roban’s website: (www.robanmodel.com/cms/index.php/home/instruction-manuals) – at the time of writing, it seems to be somewhat incomplete and was only in German. However, I am assured that by the time you read this, the EC-225 manual will be complete and also in English!

Pre-assembly

When the mechanics are in the body, access is very limited so it is important to first fit as much as possible and hence the Manual first shows the undercarriage being assembled and installed, which is already done for you! Two servos are pre-installed, one operates both rear u/c legs via a substantial cross shaft, while the other operates the nose leg. The nose leg is fitted with an oleo and twin wheels leaving you to fit the single wheels to the rear legs, which are correctly angled outwards. When extended, the legs are locked so the load is not taken by servos.

The next job is to glue in the supplied LED navigation lights and warning beacon. A control board is supplied along with extension leads, so everything has been thought of and it’s just a matter of gluing the right one in the right place, red on fin top, under belly and left stub wing with the green on the right stub wing. A clear led was included that is not used.

Mechanics

As mentioned the mechanics are supplied assembled and ready to accept the motor, servos, rotor head and the tail boom. These SM2 ‘compact mechanics’ are used throughout Roban’s super scale range of 19 models with the only difference being the position of the tail drive to suit the boom position of each model.

The SM2 mechanics use a 2-stage reduction with a toothed belt drive from the motor to a lay shaft behind the main shaft that drives the main gear through a reduction gear set. The lay shaft also drives speed up gears for a second shaft running down to a gear box that drives the tail drive shaft. This lower gearbox is similar to a tail gearbox that is cleverly rotated so the ‘output’ shaft is used as the input, which means the shaft is properly supported either side of the bevel gear. The side frames are carbon sheet, spaced with metal bearing blocks and motor mount etc. with carbon spacers further bracing the assembly. This layout means that the main drive components are very compact and will fit into the ‘doghouse’ with the tail drive dropping down behind.

I was keen to inspect the mechanics as in the past the gear mesh needed adjusting and I was pleased to find that the mechanics ran very smoothly with the correct gear mesh throughout and all the gears ran true.

The metal 5-blade rotor head is supplied fully assembled; all you need do is adjust the length of the pitch control rods – note the ball ends are slightly ‘handed’ with the moulded ‘number’ on the outside. I checked the screws were all tight and the blade grips rotated smoothly without axial play, which they did. I also noticed the blade axles are now retained with a cross pin – excellent!

Tail Drive

Attention turns to the tail boom, which is supplied cut to length and so just needs the tail tube drive installing – use grease on the bearing supports to help them slide in. The boom support clamps can be removed from the frames and fitted to the boom – a screw into the boom locates the rear one, while the front support is recessed to accept the boom, all of which makes it easy to fit.

The boom stays are ready to fit, although it is not clear where they attach to the mechanics. I drilled 3 mm holes – note these need to be low enough to clear the fuselage.

Servos and Mechanical Set-up

Powerful metal geared servos are recommended so I chose 3 Spektrum H6040 for the eCCPM and a H6080G for tail control, which I hoped will be powerful enough for the 4-blade tail rotor. The servos drop into place – I chose to use JR heavy duty arms with the ball on the inner hole. The reason for using a short radius, is that the s bellcranks double the output making the controls very aggressive. I believe this is to help keep the control assembly as compact as possible so it’s a good idea to compensate by using short servo arms.

At this point it is important to do the mechanical set-up because access to the tail linkages is very difficult when it is in the fuselage and anyway it’s easier to do on the bench! I plugged the servos into the receiver and the mechanical set-up was done in the usual manner of servos centred and the arms at 90º, then the swashplate bellcranks were set level followed by the swashplate at 90º to the main shaft. With the rotor head fitted (it uses a M4 shanked bolt and 2 M3 clamping screws), the blade grip angle was set – this gave -2º pitch, but would be changed later. I spent a lot of time setting up the blade grip angles using a digital incline meter to get them within a fraction of a degree – it is easier to get it right on the bench than working out which of the 5 blades is out of track when flying!

I fitted the tail servo and tail pitch rod that runs to a lever mounted to the intermediate gear box – I did need to ‘fettle’ the lever for it to move smoothly. At this point I like to check the mechanical smoothness of the drive train by turning the main and tail rotors looking for tight spots and excessive back lash, which have been present on earlier mechanics… The drive train is impressively smooth with no tight spots and the total backlash through 5 gear sets, is only some 5º rotation! This is a very good and shows Roban has made good improvements to the SM2 mechanics.

Fuselage Preparation

The retract servos are plugged into a 3-way extension and so run from a single receiver channel. When I tested these, the wheels did not fully retract or lock down fully so I increased the Travel Adjust to 150%. The wheels now retract about half into the fuselage, which is just like the full size and they lock down fully.

The two lighting systems (the consul lighting has its own control board) run off receiver power, so as the servos are at the back, I put the main lighting unit there as well, but I needed to run power to the front consul lighting. Extension leads are supplied but routing the lead under the floor through the bulkheads was not easy and took ages… It would be nice if this extension lead was installed at the factory – like the one for the retract servo!

I wanted to check how much current the lighting and retracts would draw, so I wired power through an amp meter: with the lights operating and the wheels up, 0.18 A and the same with the wheels down. With the model sat on the wheels the current went up a little to 0.23 A and during transition it was 0.23 A. This is not much current and as the KONTRONIK JIVE Pro 120+ HV ESC I would be using, has an 8 A constant, 20 A peak BEC, I was confident to run the whole system from the receiver. To tidy the wiring, I used a ‘Y’ lead for the 2 lighting feeds and plugged that into the ‘spare’ lead on the retract loom.

The final job here was to check the fit of the fuselage tail section – it fitted perfectly with a good tight fit. Six M2 screws secure the tail section and holes are drilled through so the supplied blind nuts can be glued in place.

Motor and ESC etc.

All Roban 700 size super scale models are designed for 12S LiPo power and specify a 450 Kv motor, which with the standard gear ratio of 13.83:1, provides a governed rotor rpm of about 1300. I chose a KONTRONIK PYRO 700-45L (you need the long shaft version) and a KONTRONIK JIVE Pro 120+ HV ESC, which includes their excellent governor and very reliable 8A, 5 – 8 V BEC. Another benefit of using the JIVE Pro for any scale model is the variable spool up time (8 – 60 sec), and it also has an internal log accessed by optional modules plugged into the sensor port (see http://www.kontronik.com/).

The motor slides into place and the primary belt pulley is tensioned by a pair of screws that pull the motor mount forward before tightening the motor securing screws that lock the mount in place. It is worth checking the belt tension after a few flights.

I always like to use an EMCOTEC SPS (Safety Power Switch) that operates as an electronic switch between the LiPo packs and ESC, operated by a remote switch – I use the magnetic ‘remove before flight’ plug version. The advantage of the SPS is that you can connect the packs in complete safety and the system is only live when you pull the plug, it also includes an anti-flash circuit that prevents the spark when connecting some ESCs – the JIVE Pro has its own circuit for this…

Final Assembly

It was now time to fit the 3-axis gyro and as I have had great results with the Bavarian Demon 3X, I was very keen to try their new AXON. This is not the place for a review of the AXON but I will say that the set-up procedure is much improved – it was good before but now I can use my iMac and the interface is really very, very good AND they are working on a Smart Phone App to make it easy to program at the field. The AXON can be mounted with any axis in line with the model and in any attitude. I chose the horizontal plate under the servos, HOWEVER this is not perpendicular to the main shaft, so I made up a tapered plate to bring it to the correct angle and the AXON was fitted there. I chose to use the supplied wiring loom with a JR RG812BX receiver that was mounted on the side of the mechanics. The AXON can also be used with a serial input such as JR’s X-BUS, or with 2 Spektrum satellite receivers as well as with JETI receivers. The mechanics use 120º eCCPM swashplate control, so this was selected, the servo frame rate was set and I chose the ‘normal/scale’ flight response option. The AXON offers many new features including 3 ‘banks’ that can be selected from the transmitter via the head gyro channel, which allows you to try different flight settings. It also has Horizon and Rescue modes as well as a sophisticated Governor mode.

It was now time to install the mechanics into the fuselage. With the tail rotor gearbox removed, the boom slides into the body and with a little fiddling the mechanics drop into place. I found that with the front of the mechanics sitting flush on the woodwork, there was a 2 mm gap at the rear so I used a couple of thick washers to take up the gap. The fuselage tail section slides over the boom, making sure it passes through the foam positioner in the pylon section. You then attach the tail gearbox.

The total width available for the LiPo packs is some 120 mm and with my arrangement the max. length of pack is about 160 mm. As the model showed signs of being a bit tail heavy, I opted for heavier high capacity packs to help with the CG and give longer flight times – I chose SLS XTRON 5800 mAh 6S packs, which are rated at 30C/60C, they measure 160 x 45 x 55 mm and weigh 900 g. The on-line price for these is a very reasonable €111.10, and they are supplied fitted with XT90 connectors!

Scale Bits

We start with gluing in place the illuminated consul – I had already sorted out the extension lead for the lighting so it was soon in place. A nice detail is that the cockpit floor is finished with a rough textured grey paint to replicate the full-size floor. The 2 pilot seats are next – the head rests needing adding, these were followed by the cyclic and collective sticks that are nicely moulded with coloured button/switches. Next 11 passenger seats are glued in place – these are very light, a total of 87 g, while the pilot seats each weigh 30 grams which is fine because nose weight won’t go amiss…

Now we turn to the exterior scale bits AKA ‘knock off bits…’ two engine intake filters are supplied, as are various aerials and rather nice Pitot tubes. The passenger side steps clip into a series of holes making them very secure, which adds to the overall presence of the model.

The horizon tail plane takes a bit more attention as the leading-edge slat has to be glued in place – to make this stronger I used very small screws through the underside of the ribs. The tail plane fits neatly into a recess in the tail pylon – I glued and screwed this in place, which meant removing the tail rotor and panel so I could drill into the end of the tail plane. I used a silicone glue with 2 M3 self-tapping screws to hold it in place and hopefully prevent it vibrating in flight!

This leaves the decals, which I find the easiest job to mess up! The good thing is that Roban have improved the quality of the water slides – they are now pre-cut so cut them out oversize, soak it in water until ready to slide, position and gently slide the backing out, leaving the decal in place. Now use a soft cloth to squeeze out excess water and air bubbles – then leave it alone to dry completely!

The five 700 mm semi-symmetrical main rotor blades are supplied ready painted with a grey leading edge. I checked the weights: 3 were 135.0 gram, one was 135.2 and the last 135.7 gram, which is good enough! The 105 mm tail blades are nicely finished with red tips and grey leading edge.

The finished model fitted with rotor blades but no LiPo came out at 7.67 Kg, which gives a flying weight of 9.47 Kg.

Flying

Finally, the day arrived for the Super Puma’s maiden flight- it seemed to take ages for the weather to co-operate with myself and Ian Peckett, who had offered to take the flying photos. The AXON manual suggests starting with low gain settings on both the tail and head – I have the tail gain on a 3-position switch, and the head gain on a rotary switch so both can be adjusted from the Tx. As the JIVE PRO was set in Governor mode, the throttle ‘curve’ was set at a 70% straight line from about 30% stick travel allowing me to control the rotor rpm and be able to hover the model before selecting Idle Up (70% straight line) for circuit flying. The Pitch curves were set at about -3º, +4.5º at mid stick and +10º at top stick.

Batteries charged and checked, the gyro direction was checked – again, so with Ian ready I open the throttle… The rotors started nice and smoothly and picked up speed with no vibrations, then it became light on the wheels and up she came into the hover. The blade tracking was perfect and there was not a vibration to be seen, it was also running very quietly with no noticeable gear noise – wonderful! The controls were rather fierce so after about 5 minutes I landed and used dual rates to reduce the overall cyclic response plus adding a little exponential to soften the centre stick response. I checked the battery levels – about 35% used, so I hovered for another 5 minutes while Ian took lots more photos. On landing, the motor, ESC and batteries were only slightly warm to the touch – excellent!

The second set of XTRON LiPo’s were fitted and with a little more gyro gain selected, the second flight began. This time I selected Idle Up for circuit flying and what a joy it was! This is quite a big model and may not be the prettiest, but in the bright evening sunshine it looked terrific and I immediately felt at home with it flying high and low circuits with banked turns, for the camera. Despite its size, it has a surprising turn of speed and the tail power was much better than I expected. This was another 10-minute flight which left some 25% capacity in the packs!

Summing Up

The ec225 Super Puma is another stunning model from Roban with great presence in the air – a real crowd pleaser! It is a large model but should fit in most family cars, although a large estate car makes transport easier, although it needs restraining or it will roll back and forth breaking those ‘knock off’ bits!

The mechanics run very, very smoothly and quietly without any visible vibrations – even the horizon fin is rock steady! Time spent setting up the 5-blade rotor head was certainly well spent because the tracking looked perfect. I have not yet checked the rotor rpm, but at 70% throttle I estimate 1200-1250 rpm, which suits the model very well and gives an easy 10-minute flight on the SLS XTRON 5800 mAh LiPo packs.

This model was the most straightforward model to get flying properly, which I am sure is due to both the improvements in Roban’s SM2 mechanics and equally the AXON, which just worked brilliantly from the first lift-off – all I have done is to optimise the gains from the transmitter – wonderful!

So there it is, a large Super Puma with loads of scale detail, that looks terrific. It may weigh 9.47 Kg but it will fly beautifully for 10 minute on a single set of LiPo’s – what more could you want?