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SLEC Chipmunk build blog


Tim Flyer
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Cheers Ron . Yes the alloy tubes and angles are really useful. They were great for the wing sheeting. I have just cut out the ailerons and flaps . Fitting with correct gaps after capping always takes some time, and I’m being careful to make each flap the same size. One downside of building I have discovered is that aliphatic on the fingers makes my typing even worse ! 😊

Edited By Tim Flyer on 15/10/2019 10:54:17

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Here are the flat hinges going in with help of Xcel hinge cutter . The profiling is done after hinging as usual ( otherwise slotting would be difficult) . The flap has a half angled profile as it just goes down. The aileron has the usual double profile . To profile more razor planing and sanding is needed.

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Hi Jon I’m afraid I haven’t got the B yet but hopefully will do it very soon ( next few weeks/ days) if the weather improves. We are having an instructor visit our club this weekend and hopefully we will get a test date arranged soon . 😊.

I have now finished the flaps and ailerons on both wings . I must say the Kavan flat hinges I bought from SLEC are very good quality and made the job easier. The flaps and ailerons are finally fixed after covering. As in all building labelling is important. It’s very easy to get mixed up otherwise. I label everything with a felt pen . I took time to get a satisfactory fit .. if perfection required that would have taken even longer , it’s always a “best guess” fit approach as covering film or paint tighten gaps considerably. Next job is gluing in the wing joiner to the right wing . The left side has the joining box with the two bolts .

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0424e542-a67b-4567-be3d-4851235c8fc0.jpegToday I glued in the ply wing joiner into the right hand wing. Firstly I checked the fit . The ply joiner needed a little sanding to allow the inside ribs to but together. Luckily the wings were straight and the fit on both sides of the rib were ok so I didn’t need much extra work . The left hand wing is bolted to the joiner at the field via the two bolts accessed from the central left hand wing joiner pocket. The gluing in of the joiner into the right hand wing must be done carefully. Otherwise you might get a one piece wing!! I used some masking tape and was careful with the epoxy. The wing is very big and fills my small workshop( I had to have a tidy up too!) . Anyway for most of today I will have to leave the wing alone in there to give the epoxy plenty of time . I will not separate the wings until tomorrow to allow complete hardening. Hmmm maybe I will go flying 😉

Edited By Tim Flyer on 17/10/2019 11:03:40

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Here is the tailplane and elevator construction now complete. I added small balsa gussets to the right and left aerodynamic balancers on the elevator. That was to avoid hangar rash as they are quite vulnerable to knocks. The instructions were a bit vague on the elevator jointing with the joiner wire and lite ply plates . I made them the hard way taking ages with balsa tongue joints. An easier way would be just to make the complete Balsa frame . Let it dry then sand to fit the reinforcing plates, rather than all the measuring and cutting I did ! 1e004638-7dd1-4ff6-895c-fb64ddd8c5c0.jpeg

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I have finished off the tailplane and elevator now and sanded the elevator taper to the trailing edge. I haven’t sanded the tailplane leading edge in order to avoid unnecessary hangar rash before finishing.
Today I started the fin and rudder construction. That is fairly simple but also needs careful razor saw cutting. One small matter to note is to check part labelling . The instructions gave the wrong part number for the fin base , but the plan was correct. I have found it very important to check the dimensions of each required piece of wood before cutting to avoid mid labelling errors . The dimensions are conveniently listed on the back section of the instructions. The fin and rudder are now being left to set before sanding the curved profile.

3b507092-1482-4347-87cf-6a9ab77d3e54.jpeg

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One slight difference between plan and instructions which I believe I have solved ( yet to be confirmed when I get to near completion of fuselage!) is the fin base . The plans show balsa parts “TC15” and “F34” beneath and the instructions call for part TC 13 which is actually a totally different sized liteply elevator support panel ( already used!) . Anyway it’s fairly obvious that the kit supplied balsa TC15 part actually combines part TC15 and F34 . I made sure when sheeting the fin I just covered the “TC15” area.
Next job is finishing the rudder adding balance weight and brass wheel tube

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The last small “tweaks” of putting in the balancer weight and brass tube in the base have been done. The instructions are quite helpful and give good advice on using cyano to soak through pinholes after the brass tube is fitted. The tail wheel wire fits tightly and it’s also important to de-burr the bras tube before gluing in otherwise fitting the whe wire will be tough. The balance weight on the front of the rudder is apparently to reduce potential rudder flutter.

I’m looking forward to getting the fuselage started as is such a substantial size. For the last day I have been waiting for smelly paint to dry on my little Wot 4 that I repaired after a careless low level crash 😉. I must admit I totally hate painting! On this plane I plant to film cover , but will still need to paint the cowl and the wing fairings. I guess I will need to find some Oracover Red with matching red aerosols so there isn’t a bad colour clash between the main fuselage and cowling . Anyway painting is a fair bit later luckily!

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Very nice build, a Chipmung is a great aircraft. I had a Carl Goldberg one for many years and loved it. I have a scratch built airframe about the same size as this one that I need to finish, I used a Dynaflite kit as a basis for my one. I Have not worked on it in a year and a half but have decided that it must be finished. Thanks for the inspiration.

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Thank you for your kind words Chris.😊 Finishing your scratch build seems a great idea. It’s hard not to get waylaid into other projects. I suppose my restricted size workshop prevents me starting too many projects, and this one almost fills it ! A Chipmunk is such a nice flyer and so much of a “practical scale “ plane that it really makes sense to “keep one in the fleet”.

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I started preparing for the fuselage build this morning . Firstly I cleared the excess after run oil out of my Laser 180 before it spills all over the plan ! I then prepared the engine spacers . The width you need is clearly stated on the plan making it quite simple. I found a very useful short cut by using spacers I salvaged from an older wreck . Salvaging and reusing bits saves lots of time plus reduces waste! Dismantling of epoxy glued bits is incredibly easy using a heat gun! It saved me cutting and laminating new ply blocks. After a few minutes sanding I am left with two 22mm spacer blocks as required. The ply firewall is marked with an adjusted centre mark so measuring up will be easy. The engine will be mounted inverted but I will probably move it to around 4:30 to 5 o’clock so the fins are in line with the cowl intake. At this stage I’m also thinking about what exhaust I will use. Either stock laser or I might well fabricate a bendy pipe one which will give more choice on exit. There is a cooling outlet on the bottom of the firewall so I Will also consider the through flow of air out of that after entering through the front of the cowl . c24bb436-4801-4733-ab6d-0604e59f615d.jpeg

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After a bit of checking I have found what I think is a small error in the kit. The locating hole in the firewall I believe to be drilled in the wrong place . It is actually in the centre but it should be located 3.2mm to the left to allow the prop to centre with the built in side thrust . The right fuselage side is a bit shorter than the left which tilts the firewall to build in side thrust. The instructions say the hole is already offset but it is in the centre according to my measurements.

Edited By Tim Flyer on 29/10/2019 16:01:48

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I always ignore measurements like that. I just build it, fit the cowl an then plonk the engine on the front. As i deliberately mount the engine slightly short on its mounts I then make whatever modifications are needed to get the engine where it needs to be.

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This is my build so far, the Dynaflite seems to have the same design as the SLEC one. I enlarged the Roger Pegg / Radio Moddeler plan and made some changes to the tail surfaces to make it closer to scale. For the wing I went the foam wing route so that I could add the missing ribs. I got further than I thought, airframe is glassed, the wing needs filling and then MS primer so that rivit detail can be added. The idea was not to have a super scale aircraft but rather a nice flyable aircraft.cm3.jpg cm4.jpg

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Im in the 'scale at 10 paces' club myself. I have always wanted to do a fully detailed build with rivets and so on but once you are a few feet away you cant tell anyway and the time investment just dosent seem worth it. Even at 5th scale rivets might be only 1 or 2mm across anyway

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I have now decided just to mark the adjusted centre line on the firewall. I’m going to drill later like Jon suggested and just as I have done one on a number of other planes and do the drilling once the fuselage is built and I can check the cowl fit . That gives more time to decide optimal position. Possibly a 7 o’clock mounting might work well here and give the possibility for a more elevated fuel tank position , as long as my baffling is ok. 7 O ‘clock also allows easy needle valve access. Anyway all that will be finalised much later . Next the fuselage sides !

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