Kev Crozier tests the aerobat from ST Models - 26/9/11
When RCM&E’s publisher roped me in to help out with articles for the 50th Anniversary Special (2010), I suggested it would be a good idea to feature a couple of kits. The first covering one of the ‘retro’ kits that are making a comeback, and the second being a ‘state-of-the-art’ electric aeroplane to show how far things have progressed.
I'm currently having a ball flying a JR Super Voyager E helicopter using a four cell li-po set-up but I wanted a small electric aerobatic aeroplane to tuck under my other arm when hiking the short distance to my local flying patch. With my trusty JR tranny in my rucksack, together with a few fully charged Li-Pos and a flask of hot coffee, I would be all set for a full morning of flying fun. And since I wanted all of my four cell packs for the heli, the plane would need to fly on three cell packs, a number of which I already had available from flying a foam jet. The F-16 in question almost fitted the bill and was a lot of fun but with a one piece fin, I was yearning for a quick build foam aerobat with a decent rudder to enjoy some ‘proper’ aerobatics.
Enter the ST Model ‘MX-2’ which fitted this brief perfectly. Distributed to model shops across the UK by Ripmax, the MX-2 has a wingspan of 1210 mm and is pre-fitted with a 920 kV brushless motor, a 30A speed controller and four mini servos. The model is moulded from white EPO foam, which looks to be tough and fairly ding proof. A couple of large sheets of self adhesive stickers are supplied to add a rainbow of colours, giving a livery that is very pleasing to the eye. The only drawback is that there is just the one colour scheme so if your club mates take a shine to this model then you could soon be surrounded by a squadron of MX-2 clones. ST has alternative sticker sheets for this model, so it would be great if Ripmax could offer these as an option, just to add a little variety.
The MX-2 is a very fast build. Applying the stickers is the most time consuming task. The comprehensive instruction book shows the model being finished in its original ‘white’ state, but I would recommend applying the stickers to the individual components before assembly. It is much easier to stick them to flying surfaces which are lying flat on the building bench rather than putting them on after assembly.
The first task is to attach the ready made undercarriage.
This screws to a plastic plate moulded into the EPO foam. The screws supplied have fairly soft heads and the plastic is quite tough, so be sure to use the correct size screwdriver to avoid rounding the heads.
There are tales on the internet forums of the undercarriage on this model ripping out but it seems pretty tough and I have not had any problems. All the landings so far have been fairly neat and onto short grass. If you fly from longer grass it may be prudent to take off the spats to stop them from catching and bringing the model to a dead stop.
ON WITH THE PROP
The model is supplied with a 12 x 5 electric propeller, which has been carefully matched to the model. Having spoken with two or three pilots who have flown the MX-2, they say it flies perfectly well on this prop. But another experienced pilot recommended changing it for an APC as the original is quite flexible. If you are a fairly new pilot, I would stick to the kit prop as it may be more forgiving if you nose over the model during the landing. But if you are confident in your flying abilities then it may be worth changing to the stiffer prop to get maximum thrust from the motor set up supplied. I fitted an APC.
The prop adapter is of the collet type, which tightens onto the motor shaft as the prop nut is tightened. A neat spinner,
with cooling vanes built in, completes the front end. The next task is to push the fin locating shafts through the tailplane and then clip the tail assembly onto the back of the fuselage. It clicks into place and is held in position by a moulded square peg pushed through the side of the fuselage. A simple and effective solution.
With the tailplane in place, the elevator and rudder can be connected to the relevant servos using the short wire pushrods and screw-locks supplied. The servos are pre-fitted inside the fuselage with only the output shafts exposed. When the servo horns are fitted they are very close to the fuselage sides, so much so that the Z bends in the pushrods dig slightly into the foam. But this is not a big problem as the pushrods soon carve out an arc after a few blips of the controls. If you are worried about the pushrods rubbing then you can use the tip of a small screwdriver to deepen these arcs to clear the wires. Ditto the aileron pushrods, one of which I found to be rubbing against the foam.
3D FLIGHT - STEVE ROBERTS PUTS THE MX-2 THOUGH ITS PACES
When Kevin asked me to test fly and write a short ‘report’ on his new toy I jumped at the chance! I arrived at the field to witness Kevin fitting the wings to the MX-2. I couldn’t believe how easy it was to fit them. I just loved the way the wings slide into the fuselage and are held in place with just two quarter turn bolts. Genius!
The battery was fitted though its nice little hatch under the cowl’s chin and the controls were checked. Kevin had setup three flight modes on his JR DSX9 radio with various amounts of control movement and exponential.
A quick range check with the JR RD721 receiver and DSX9 transmitter showed no problems so the model was taxied out onto the strip and lined up on the runway. Kevin was ready with the camera and so the throttle was opened. The model tracked straight as a die and lifted off in no time. One click of left trim, one click of down was all that was needed. So it was immediately pulled up into a vertical climb to see what the performance was like. I was quite surprised to see the model track vertically with little or no correction, and with a nice climb rate. Vertical rolls were performed which seemed a little slow even on high rates and seemed to just send the model off track. I felt that there was a little too much aileron travel on high rates. It just seemed to create drag. Cutting the travel back actually improved the roll rate, still leaving plenty of control authority for the slow, high alpha stuff.
Personally I would like to have more movement on both the rudder and the elevator although high alpha and prop hanging manoeuvres are achievable with the current settings. Harriers are particularly nice, both upright and inverted, with very little wing rocking, just leaving the throttle cracked open a little, and are easily controlled by the rudder. Transitioning the harrier into a high alpha pass and figure of eight only needed a little more throttle to stop it descending and then balancing the controls as needed.
Large IMAC style aerobatics are a breeze with the MX-2. Loops, multi point rolls, spins etc. all just fall into place. Knife edge flight is also very nice but as I said earlier, I would like a little more rudder which Kevin is going to sort out for the next sortie. But the controls are well balanced and only a touch of up elevator is needed to hold the MX-2 steady.
Wingspan: 1210 mm
Length: 1106 mm
Motor: 920 kV Brushless (included)
Battery: 3 cell Li-po
Propeller: 12" x 5" (included)
SRP £122.99 or £174.99
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