Sterling101 Posted October 18, 2016 Share Posted October 18, 2016 I've wanted a Spitfire for a while but didn't fancy any of the off the shelf ones as I prefer to build myself so I set about looking into converting the FliteTest Spitfire into depron and adding my own touches to make it a little stronger and customise it a bit. I had the plans printed out but forgot to resize the canvas before sending it off to print so it got scaled to fit and A0 sheet instead of being a 1:1 print which meant that instead of a 42.5" span it came in at just over 49.5" - about 115% size. Not too much of a problem though as it still (just) fits in the car with the whole thing intact so I've not needed to look at removable wings yet. The first thing I did was cut the wing spars out and look at how to strengthen them. I decided a 3mm lite ply skin on either side of the spar pieces was a good idea as it gave them some rigidity which was sorely missing with out (I could bend the spar over 90 degrees to the point of breaking before reinforcement). I also got some 4mm birch ply and braced either side of the join in the centre of the wing on the angle where the two halves meet. This made the spars pretty well spot on strength wise but still allowed just enough flex to keep them from over stressing the lite ply. Other than that the main things I did before maiden was to add more box sections to the fuselage at the rear as it would twist wildly without anything to hold the shape. And the big important part was I built the battery box out of 3mm lite ply and used 4mm heavy ply for the motor mount. I based the battery box around the FT power pod design but made it fully square with the back end closed up to provide some rigidity. This was hot glued into the fuselage so the motor was all but tucked into the nose which seems to give quite a nice look to it (be even better with the proper spinner on it!). Because I didn't go with a removable power pod I made a top hatch to get to the battery. Using 3mm grey depron I skinned the front turtle deck as per the plans then cut out a section to give me access. Quick tape hinge on one side and held the other side down with a bit of tape. I added a quick cockpit cover from a piece of laminate film that I'd got lying around after laminating a parking permit which fitted perfectly! The motor I'm running is a DYS D2836 1500kv with an APC 8x4 prop. I'd got both hanging around so decided to drop them on and see how it flies. Maiden went well despite being windy but I discovered I needed to alter the linkage points as they had to be ramped up to 100% throw to get any kind of authority out of the ailerons and elevator. Did a second flight and all seemed ok so I decided it was good enough to carry on with. Quote Link to comment Share on other sites More sharing options...
Sterling101 Posted October 18, 2016 Author Share Posted October 18, 2016 So I built the rear turtle deck up in depron and re-made the nose cover with a better hatch design after the original one popped open on the maiden as it was just taped down for the first flights. After that was all done I covered the model in brown paper and PVA and gave it a coat of paint. I also popped a fixed landing gear I'd had for a while onto it so I could test at the airfield. Second set of flights were in VERY windy conditions and it still handled it fine if a little hairy turning cross wind. I needed to add some more nose weight but at the time I hadn't got anywhere to put it at the field so I taped a bit of lead underneath the nose but it wasn't ideal. The test was good though and the only problem I had really was I lost a wheel on the first flight so ended up having a scrappy landing on the runway so I removed the main gear for the second flight. I've linked the playlist on YouTube of the flights below. Gives a reasonable idea of how it flies right off the bat though. Since then I've built up a "ballast box" under the motor where I can add weight if needed for balancing up more but sadly the weather is very much against me now to test again. Still a good experience and I think it will be a great plane to fly in calm conditions if the flights so far are anything to go by! 1 Quote Link to comment Share on other sites More sharing options...
eflightray Posted October 18, 2016 Share Posted October 18, 2016 Now if only you had bought the Autumn 2010 RCM&E Special, you would have had the free 70" span Spitfire plans Also Depron, (actually 72" span), there is nothing like a Spit in flight, nice model, well done. Ray. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted October 19, 2016 Share Posted October 19, 2016 I like that Sterling 101, it looks like a quick build and a proper "chuck it in the car-go and fly" model. I wouldn't have worried about the bendy spar though, all it actually does is to maintain the distance between the wing skins, the bending stresses are transmitted horizontally through them and the spar is there to ensure that happens by stopping them buckling. You do need a strong point to fix the undercarriage though! Good one mate. Quote Link to comment Share on other sites More sharing options...
Sterling101 Posted October 19, 2016 Author Share Posted October 19, 2016 Posted by Colin Leighfield on 19/10/2016 19:02:45: I like that Sterling 101, it looks like a quick build and a proper "chuck it in the car-go and fly" model. I wouldn't have worried about the bendy spar though, all it actually does is to maintain the distance between the wing skins, the bending stresses are transmitted horizontally through them and the spar is there to ensure that happens by stopping them buckling. You do need a strong point to fix the undercarriage though! Good one mate. Took around 4 hours to build including the additional work to strengthen things up. Definitely needed a bit more around the spar though as without it I could bend the wing up almost 90 degrees. Nice hefty lump up birch ply underneath though for the undercarriage to stick down to. Just need some better weather now to get it back in the air again! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 19, 2016 Share Posted October 19, 2016 I agree it looks like it flies very nicely. You are probably right about needing fairly calm conditions. If the wings are indeed that flexible just be careful about adding too much weight or you may find they start to flex in flight and that tends to really upset its flight characteristics. Quote Link to comment Share on other sites More sharing options...
Sterling101 Posted October 19, 2016 Author Share Posted October 19, 2016 Posted by Simon Chaddock on 19/10/2016 23:02:18: I agree it looks like it flies very nicely. You are probably right about needing fairly calm conditions. If the wings are indeed that flexible just be careful about adding too much weight or you may find they start to flex in flight and that tends to really upset its flight characteristics. After the mods and wrapping the wings are now very strong with very little deflection even in Sunday's high winds. I was surprised exactly how well it flew in gusts that were making me shift around in the pilot box. Just need the weekend to stay dry and a bit less wind is always welcome Quote Link to comment Share on other sites More sharing options...
Sterling101 Posted October 29, 2016 Author Share Posted October 29, 2016 Last Sunday's test flight in bloody high winds. Still flew well though, just needed more speed on landing but still learning and no damage done. However on the Saturday I had a failure on the tail so had to retrieve from a tree and rebuild the back end. Now much stronger, bit heavier, but still immensely flyable even in winds that make it hard to stand upright on the flight line! https://youtu.be/_aS2iKyo834 Edited By Sterling101 on 29/10/2016 22:02:43 Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted October 30, 2016 Share Posted October 30, 2016 It certainly looks like a good flyer, you must be pleased with that. Quote Link to comment Share on other sites More sharing options...
Sterling101 Posted October 30, 2016 Author Share Posted October 30, 2016 Just need to get it airborne in still conditions to get it trimmed in. It has now lost around 250g since that flight so should fly quite well hopefully. Typically the one weekend where I was away and couldn't fly the weather was perfect for it! Quote Link to comment Share on other sites More sharing options...
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