Mike Smith Posted August 20, 2014 Author Share Posted August 20, 2014 To secure the lower cowl, I've made a couple of retaining tabs which you can see glued to the bulkhead, between the upper and lower anti-vibration mounts. The lower cowl slides up into these from below. It is then secured by a small screw into the bulkhead near the bottom - this is accessed through the air intake. Quote Link to comment Share on other sites More sharing options...
kc Posted August 20, 2014 Share Posted August 20, 2014 That looks fine Mike. There are several other ways of bending balsa 1. see many of Peter Millers builds ( Jezebel for one ) where he glues one end down and when glue is dry bends the rest by using a heat gun. 2. Putting masking tape, Solarfilm, Solartex, tissue etc on the outer surface allows balsa to bend more. Try it on a bit of scrap! 3. ammonia but it's not worth the health risks. 4. two thin layers are often better - for example 2 layers of 1/16 will work better than one layer of 1/8. Either when using sheet or when planking. Edited By kc on 20/08/2014 17:50:24 Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 20, 2014 Author Share Posted August 20, 2014 I'm thinking of using method 4 for the over-wing section. On the subject of the wing, I've beefed up the wing seat area with some 1/4" balsa to give a little more glue area. Quote Link to comment Share on other sites More sharing options...
kc Posted August 20, 2014 Share Posted August 20, 2014 I managed to get a bendy piece of 1/16th balsa to curve around that sort of radius in one layer without any trouble. I presume it's a fixed ( non removeable ) wing on your version? If so the top part is glued to the wing. It's much more difficult making a fairing to fit the wing and be detachable to get at the wing bolts. Much easier to make a flat top to the wing and then the curved part to go on top. Reason is the wing is so thick at one point that the fairing has to be very thin there. Very tricky compound curves!. Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 20, 2014 Author Share Posted August 20, 2014 Yes, it's a fixed wing... gluing as we speak... so that should simplify things. I'm just wondering if I might need to add a central former on top of the wing as it's quite a span. Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 20, 2014 Author Share Posted August 20, 2014 The lower cowl and battery hatch fit together surprisingly well Quote Link to comment Share on other sites More sharing options...
kc Posted August 21, 2014 Share Posted August 21, 2014 I plotted a central former for a tapered cowl by drawing both end formers on top of each other onto a bit of balsa.( centred and at the correct height ) Then put a series of dots half way between the two ( done by eye but measuring if needed) Joining the dots produced the line to cut to. Result is a former which is correct for halfway between the others. I could have halved the distance once again to make further formers to fit at the quarter distances. Edited By kc on 21/08/2014 18:01:16 Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 21, 2014 Author Share Posted August 21, 2014 I put in two additional formers in the end, plus a stringer (I think that's what you call it) I then steamed the 1/16" balsa sheet round a piece of plastic pipe. ...et voila! Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 21, 2014 Author Share Posted August 21, 2014 The first layer pinned into place over the formers... a little tricky to get the shape right due to the compound curve caused by the wing profile. ...and the second sheet, curved and ready to fit Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted August 21, 2014 Share Posted August 21, 2014 Real nice job of the front end Mike, I would be tickled pink with work that good Why the anti vibration mounts on electric ? I thought they were less likely to produce it, but I could be wrong (again ) John Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 21, 2014 Author Share Posted August 21, 2014 Thanks John, the only reason I'm using the AV mounts is simply because I've copied a few design details from my Mini Panic and they were recommended for that. My only concern is that my LMS hasn't had any of these in stock for ages so I got these from Farnell and they seem a little softer than those on my Panic. As you say, they're probably not essential with electric, although my previous project (the Citabria Pro) which didn't use AV mounts managed to rip the front bulkhead off twice due, I think, to some kind of resonance. If these mounts prove to be too soft, I can either replace them with the harder ones if they ever come into stock, or some rigid stand-offs. Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 25, 2014 Author Share Posted August 25, 2014 The top sheeting over the wing is now complete... ...and meets up nicely with the top hatch/cowl (the difference in colour is mainly down to the use of some sanding sealer on the hatch) ...and for completeness, seen here with the lower cowl too Edited By Mike Smith on 25/08/2014 18:50:39 Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 25, 2014 Author Share Posted August 25, 2014 And now for the final piece of the jigsaw... the upper decking for the rear of the fuselage... 1/8" sheet, gently curved round F3. You'll notice I added a small strut between the fuselage sides to prevent them collapsing inwards under the pressure of the upper decking I topped this off with a couple of layers of 3/16" sheet (not pictured here), carved and sanded to a rounded profile. Edited By Mike Smith on 25/08/2014 20:16:16 Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 25, 2014 Author Share Posted August 25, 2014 The original plan calls for 1/64" ply sheet for the canopy, but I ended up making mine from 1/16" balsa sheet. I decided to form this first round a piece of 1/8" shaped the same as F3 (only slightly smaller). I feathered the inner edges to accommodate the curvature of the decking ...and once happy with the fit, I glued it in place onto F3 and the upper decking Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 25, 2014 Author Share Posted August 25, 2014 A quick preview of the completed airframe... Quote Link to comment Share on other sites More sharing options...
Jack Banner Posted August 25, 2014 Share Posted August 25, 2014 That looks very good indeed. I am sure it will fly a treat. Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 25, 2014 Author Share Posted August 25, 2014 Thanks Jack, I certainly hope it will. I did a quick fit of the main components and the CoG wasn't a million miles from where it should be so I'm keeping my fingers crossed that it doesn't need any lead to balance it. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted August 25, 2014 Share Posted August 25, 2014 I agree, very good looking model and great work John Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 28, 2014 Author Share Posted August 28, 2014 Thought I'd knock up a simple tail skid. I was going to put a steerable tail wheel on, but it looked a bit too big and clunky. Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 29, 2014 Author Share Posted August 29, 2014 A couple of shots of the internals: Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 29, 2014 Author Share Posted August 29, 2014 Ready for covering Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 29, 2014 Author Share Posted August 29, 2014 Now for the bit I hate... covering commences!! Quote Link to comment Share on other sites More sharing options...
Jack Banner Posted August 30, 2014 Share Posted August 30, 2014 Not finished yet Mike? Quote Link to comment Share on other sites More sharing options...
Mike Smith Posted August 30, 2014 Author Share Posted August 30, 2014 LOL... sorry Jack, am I not progressing fast enough for you? I had a bit of a setback... when checking the elevator, the solder joint on the internal control horn failed so I had no option but to "extract" it via a bit of keyhole surgery. I should have silver soldered it but didn't... you live and learn. I will now fit an external horn and new pushrod. The following pics bring you right up to date with the project. Quote Link to comment Share on other sites More sharing options...
Jack Banner Posted August 30, 2014 Share Posted August 30, 2014 I thought something must have happened to slow you down! I also suspected you were going to make a lovely job of the covering and I was right too. It looks pretty sharp. Are you going to maiden it tomorrow? Weather looks half decent round here for a change. I may get to fly. Quote Link to comment Share on other sites More sharing options...
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