christchurch and district model flying club

Seagull Arising Star

Electric, By Terry Sullivan

Part 2

Photos by Terry Antell, Model and all equipment supplied, By Simon Willey of Model Pro,, Except Datalogger from Mike Redmond of Aurorra Ltd

The first task was to remove the fitted motor mount, and the fuel tank neck piece was also removed to give a bit more room. The Radial mount for the motor was then placed in position, we found that the top bolts fitted perfectly, but the lower ones did not. Drilling the required 5mm holes proved tricky, as the standard length drill bit was not long enough to make room for the drill chuck, but a little creative thinking solved this. I had a bit intended or use with a cordless screwdriver that has a hexagonal end. This was put in a socket, and a short extension was put in the drill chuck. Removing the caged nuts from the holes from the original holes was simple, we just put the bolts in and tapped them out. Refitting them proved more awkward. More on this later.

The IC Motor mount removed. The 2 lower mounting holes are drilled out and can be seen as the outboard holes just above the nose wheel pivot

I then commenced construction as per the manual. The servo tray needed some trimming, but this is far better than the holes being too big! This also applied in the wing. One point on the wing, I found some pieces in the box and a picture in the manual that showed them fitted to the trailing edge centre section, but not a word in the text! Small potatoes for me, but a beginner, without advice from someone more knowledgeable, could worry about it, not knowing what they are for. I remember when I was building my first model a series of panicking emails to the designer to clarify a very minor point! Luckily he has a sense of humour! The main points of the construction were (1) fit wing joiner and glue the wings together, (2) remove the covering from the tail slots and the tail feathers and glue them in, (3) fit and connect the servos, (4) fit the undercarriage. Where gluing was needed I used a quality epoxy.

 Back to refitting the lower caged nuts for the motor mount. At this point we were still working through the wing hole, but later we realised that making a front hatch was both simple and helped a great deal. Life would have been far easier if we had done so now. The hatch was cut using an angled scalpel so that it already had an edge to rest on. Then a small lip was glued to the underside of the front edge to hook under the fuz top. Without this, we found that reaching the rear of the firewall to hold these in place was tricky, so a piece of 4mm studding was employed. The caged nut, which is the type that has spikes to grip the wood, was threaded onto the end and given a few turns. This was then pushed from the wing opening through the firewall from the back and out the front. A washer was cut to clear the fittings at the front and a nut put on. Screwing this up by hand and then with an open-ended spanner pulled the lock nut perfectly in place. Whilst the studding was in place, we also looked to see if there was any right thrust or down thrust. There is a bit of right thrust, but if there is any down built in, it is only a degree or so. However, the motor mounting to be employed gives the capacity to fine- tune this at a later date if required

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This picture shows the area immediately under the wing. The Datalogger goes opposite the Receiver. You can just see the aft end of the battery tray. The Rx switch is not fitted in the position provided but put in the side of the fuz above the main undercarriage as it makes no sense to me to have to remove the wings to switch off! By the switch you can see the Allen key for pushrod adjustment, held by a bit of heatshrink tubing taped on the side – I always lose these, but not now!

 Simon had supplied some 4mm bolts, washers and tubing sleeve to mount the motor, and these fitted perfectly, a dab of thread lock being applied as a matter of course.

The tubing, as well as making the mounting tidier visually, also spaces out the motor to the correct distance. The completed mount is strong enough to lift the model and hold it horizontally.

 With the motor secure, it was now time to turn our attention to the requirements for the Centre of Gravity. By trying things out we found that the Flight pack and Receiver pack needed to be well forward, as far forward as possible. A useful tip was passed to me at this stage, the material used to make the model has some treatment that means that self adhesive velcro is not very adhesive. Pouring a little runny CA on the area and allowing it to go off completely before applying the velcro cures this. Using this method, the Receiver pack was attached as far forward as possible on the right hand side.

I dislike having batteries not fully supported and protected against any bumps, so I taped a foam and balsa “bumper” to the front of the battery to prevent any damage in the event of an arrival. A model as simply constructed as this would be fairly easy to repair, but not if a ruptured lipo has caused it to be burnt to ashes! As there are the motor mounting studs at the front, protection against these piercing the pack was deemed wise. I also decided that it was unwise to simply have the battery resting in place, so a basic battery tray was fitted. I did this by first shaping a piece of square balsa stock to fit the front former, which is rounded to hold the fuel tank. I then used a sheet of balsa cut to the battery size and with a little scrap triangular stock glued to the sides and fitted this in, sloping it down to meet the firewall at the bottom and out backwards. The battery can then be secured using a rubber band at the back, which will also be used to prevent a battery short by putting one cable under it on one side and the other cable on the other when not in use.  The components were installed as per the diagram

 Another item I had to test and write up is BNB DPR –50 Data logger from Aurorra Ltd. Data that Simon sent me suggested that the motor would pull 53amps with this prop, so I changed the prop for a 12x8 one, as the logger only goes to 50 amps

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[Contents] [Chairman's Chatter] [Editorial] [Diary of a Flier] [Sealand Flies!] [Nietoperz] [Brian's Spitfire] [C&F 2007] [Seagull Arising] [Harry Spotter's] [St Louis Blues]