Stan Craine reviews the Ripmax Trainer 40

After a five years lay off from flying and with the vain hope of my teenage son joining in, I purchased an A.R.T.F. high wing Ripmax Trainer. The large colourful box contains the two wing halves, a main fuselage, tail and rudder along with a couple of bags containing almost all that is needed to complete the model. The assembly manual is fairly comprehensive and far better than some oriental imports. What you will need are; Fast and slow setting epoxy, Superglue, Pair of good pliers for bending control wire ends, Small drill suitable for making a hole of the right diameter in the servo arms, Silicon sealant to prevent fuel passing the neck of the tank and soaking into the airframe, Short length of silicon fuel tubing, Masking tape The control surfaces are already hinged and pinned in place. The entire airframe is covered with a pre-painted plastic film. This covering was generally tidy but needed slight heating to remove wrinkles from the underside of the fuselage. This is a common problem. Supposedly due to the variation in climate between the Far East, where I believe the kit is manufactured and the UK. A small travel iron is a fraction of the price of genuine covering iron and works well if used with a bit of kitchen roll or lint free cloth.

Very good assembly instructions are provided so what follows is a few minor improvements, alterations and observations. Generally speaking the accessories were of reasonable quality but the plastic clevises seem a little “brittle”. If I could readily obtain different ones locally, I would have changed them. The spinner is a little too long and this prevents a good contact with the starter cone when trying to start the engine. For a small sum it would be worth purchasing one of similar diameter and replacing it. Wheel collets are provided and I prefer to clean the end of the under carriage leg and solder a washer on to it to prevent the wheel sliding up and binding with the leg. I then file a small flat on the tip for the collet screw to seat on. It’s difficult to land with one wheel missing! The alloy engine mount has a clamp type fitting where the engine mountings on the engine case are sandwiched between two metal plates and the engine mount itself. The underside of the mounting is grooved to hold the nuts whilst they are being tightened. Despite this I found fitting the engine awkward. A spare lock nut is provided for each bolt but I chose to fit nylon locking nuts. I was concerned that the engine may work loose and wreak havoc. The side of the fuselage is fairly thin so I glued a pair of ¼ inch strips of soft balsa along the inside of the fuselage to provide a wider wing seating area. Once that was done I was able to fit wing-seating tape on top of this. The reasons for this are three fold, one it increases the wing seat area reducing the chance of creasing the wing, two it helps prevent the wing moving and three provides a seal to prevent fuel entering the compartment. Joining the wings was fairly straightforward, my only variation being to use a dolly peg to ensure the trailing edge of the wings remained aligned. Once joined, masking tape was placed ½in either side of the central joint and slow setting epoxy was spread over the joint using a piece of plastic card. Remove any surplus glue and take the tape off by peeling it back on itself before glue has set leaving a tidy seam. This adds nothing to the strength but prevents moisture / fuel from soaking the joint Do not allow the glue to run, try to keep the wing horizontal to avoid this. I used fine felt tip pen to mark the tail surfaces prior to removing the covering for gluing. Careful use of a scalpel blade is needed to avoid damage to the balsa tail/ rudder but the covering MUST be removed to ensure the tail surfaces are glued correctly. ( See later ) One item I did find to be a trouble spot was the steerable nose wheel. The arm is set at 90 degrees to the wheel and parallel to the engine bulkhead. This limits the travel to the left. To reduce this problem I opened up the hole for the throttle wire and placed a piece of fuel tubing over the wire to act as a sleeve. The bulkhead was also sealed with a polyurethane varnish to prevent fuel soaking under the covering. Once happy with the fuel tank position I used clear silicon sealer to close the gap around the neck of the tank. The plan shows a three tube fitting on the tank but the one supplied only had two. This doesn’t make a great deal of difference it just means that you remove the pressure feed from the exhaust to fill the tank. A different colour fuel tube helps to identify the fuel feed from the pressure feed. I used a dolly peg once more to hold the control surfaces whilst I aligned the neutral positions of the servos. The peg is simply ( gently ) pushed over the gap between the control surface and the fin / tail etc to hold it in place enabling you to measure point at which to bend wire at servo arm end. The servo arms are connected to the operating rods with small metal fasteners. These are basically a threaded cylinder with a hole in the side and a screw protruding through the bottom. ( A common device found on a lot of ARTF models ) The easiest way I found was set the servo arm so that at neutral it was at 90 degrees to the body of the servo. Having selected an arm of suitable length I drilled the arm to fit the screw in the fastener. Insert a small screwdriver into tube and screw the retaining screw into the arm and then superglue the lock nut on the other side of the arm. The engine I chose was an OS 40LA. Other than running in as directed by the manual little else was needed to get the engine performing well with a reliable tick over. I found it unnecessary to adjust the slow idle screw and would suggest you don’t tamper with this unless absolutely essential. The servo arm linkage makes fine adjustment a simple case of slacken the grub screw and moving the connecting rod a fraction in the required direction.

Having waited for a nice bright day with little breeze, about twice a year in the UK between October and March, I took the trainer to the local flying site. Having checked servo throws, throttle setting, confirmed centre of gravity, range checking the radio etc. (again ) I refueled, started the engine once more ( Having warmed it up already ) checked mixture setting by inclining the fuselage 45 degrees I finally put the plane on the tarmac runway. Viewing the runway ahead I saw a lump of turf directly in line with my intended flight path. Well to be safe I thought, I pushed the tail plane forward to adjust the direction slightly. It was at this point that my shin made contact with the right tip of the tail. Despite this being a light contact the leverage was sufficient to SNAP the left fuselage side and top decking along with the joint at the front edge of the rudder. I am not exaggerating, this contact was very slight and I am absolutely amazed at the damage that was done. There is no way that I would superglue this damage and consider flying without checking the underlying structure. See picture Removal of the covering revealed a very thin fuselage side (Almost transparent) and a distinct lack of adhesive on the fuselage former that is positioned just behind the crack. This little episode has shattered my confidence in ARTF models. A repair has been made but I will consider building from kits as a better option in future, at least you know what’s under the skin. To be fair, I may have been unlucky with this model in regard to the quality of materials and building. Another identical model used by a fellow member of my club ( About 10 years of age!!! ) has given good service and flies as you would expect of a trainer with a flat wing section. Now waiting for better weather, the second attempt I’m hoping will at least see it move off the ground.

The Ripmax trainer has redeemed itself and has proved to be a delight to fly. Despite my previous "minor" adjustment to the models airframe, it flew straight off the board and needed very little trim adjustment. With the control surfaces set up as per the instructions it will perform all the manoeuvres a trainee pilot could need. The dihedral and flat bottomed wings don't help in my aerobatic routine! Landings have proved easy providing they are into wind! The model is lightly loaded and can be affected by any sudden gusts or side winds. Ground handling is excellent, this is the first model that I have been able to taxi into the take off position, land and then bring back without a good walk at some point in between.The excellent ground handling has been greatly assisted by the OS40 LA (fitted without side thrust ) which has proved to have plenty of power and superb tick over. No forced dead stick landings being a big plus for a novice . The foam rubber tyres will need replacing fairly soon and it would be worth fitting slightly larger wheels especially if flying off grass.The only other modifications I would suggest is to slot a small piece of plastic or nylon into the wing tips as these will scuff the ground first on those," less than perfect landings". The only other modifications I would suggest is to slot a small piece of plastic or nylon into the wing tips as these will scuff the ground first on those," less than perfect landings". To date all my attempts to return it to its component parts have been unsuccessful. Overall the Ripmax Trainer and the OS40LA have been an excellent combination but " Handle with care" when transporting.

Article by Stan Craine for Bumpy Green Model Aerodrome
March 2004