Chinesespaceman_ Posted March 12, 2009 Share Posted March 12, 2009 Hi Richard, yes it's me the Chinesespaceman, not sure what's changed on my profile? Like you I am going with the PolyC rather than epoxy, but have not sheeted the wings or control surfaces. Am away this weekend, but will get at it the following weekend and post some photos. Cheers Gav Quote Link to comment Share on other sites More sharing options...
Chinesespaceman_ Posted March 22, 2009 Share Posted March 22, 2009 Hi Richard, I've applied Poly_C and 0.6oz glass to the leading edge sheeting on my wing. I got really bad warping of the sheeting - the wood swelled up in the areas between the ribs. Did you experience any such issues? I was careful only to give a very light first coat. Have now replaced the top sheeting on one side and ready to go again. Really nice to apply and no-mess, I can't see that I would ever use eopxy after having used this. I have emailed RC World to see if it is okay to first use a sanding sealer, stopping the Poly-C from soaking into the wood and making it swell as if soaked in water. Cheers Gavin Quote Link to comment Share on other sites More sharing options...
Chinesespaceman_ Posted March 22, 2009 Share Posted March 22, 2009 Hi Richard, I've applied Poly_C and 0.6oz glass to the leading edge sheeting on my wing. I got really bad warping of the sheeting - the wood swelled up in the areas between the ribs. Did you experience any such issues? I was careful only to give a very light first coat. Have now replaced the top sheeting on one side and ready to go again. Really nice to apply and no-mess, I can't see that I would ever use eopxy after having used this. I have emailed RC World to see if it is okay to first use a sanding sealer, stopping the Poly-C from soaking into the wood and making it swell as if soaked in water. Cheers Gavin Quote Link to comment Share on other sites More sharing options...
Richard Duvall Posted March 22, 2009 Author Share Posted March 22, 2009 Gavin, The instructions I read before use clearly warned of the risk of warping as Poly-C is water based; it recommended the use of sanding sealer first. I've used it and had not any problems at all. Quote Link to comment Share on other sites More sharing options...
Richard Duvall Posted March 23, 2009 Author Share Posted March 23, 2009 Having got to the stage where preparation is needed for the fitting of various components in the fuselage, I've done a trial fit of the engine and it looks as though I may have to cut a hole in the bottom of the cowl to make room for the engine rocker cover of my SC70. May also need to trim a little off the engine mount which snags the upper part of the cowl. Perhaps going for the biggest engine was not the right option! The good news is that the exhaust nicely fits into the space beneath the tank box and the plastic extension can either come out of the gap betwwen the bottom of the cowl and the fuselage or I can make a hole in the cowl which I am leaning towards as it would avoid the exhaust running so close to the fuselage. In the absence on any specification exactly where the engine should be positioned, I am assuming that it needs to be such that the rear of the spinner is a couple of mm in front of the cowl. I've also got to work out how to get extensions to the needle valve and the choke to operate outside the cowl. No problem in fixing extensions but the question is how to fit the cowl with them in place. Suggestions would be welcomed! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 23, 2009 Share Posted March 23, 2009 I use a long allen key through the front air intake to fix my extension which exits the port side of the cowling. A friend's version (which I set up and test flew for him on Saturday - it flew really nicely but as he's using a Y lead on separate aileron servos with no inbuilt differential needed more rudder in the turns than mine) has an SC52 which has the needle extension exiting on the other side just behind the small scoop - and he can tighten the fixing screw through the scoop! Quote Link to comment Share on other sites More sharing options...
Graham Lee Posted March 24, 2009 Share Posted March 24, 2009 Hi Richard I hope this can be of some help in positioning your engine and exits for exhausts. Place your engine minus exhaust on the mount and rubber band it securely to the mount Then place your cowling over engine and centre the drive shaft then position your engine (push or pull) as you say the prop back plate a couple of mm in frount of the cowl. I taped my cowl to the fuss at this stage I like at this point fit the prop and spinner to see what it looks like depending weather your useing a spinner with or with out a backplate. When your totally happy with your engine and cowl position drill through the cowl into your four wood retaining blocks and fit screws securely making sure nothing moves. Now remove the cowl and mark and drill for your engine mounting for bolts with ni-lock nuts. Replace your engine with bolts and your cowling with screws. At this stage you have to do a few measurements where you require exhaust and needle valve holes are required. Look through the engine cooler hole this will help Make a smaller hole than is required at these positions do the exhaust first so you can see by looking through the hole which way you have to enlarge the hole. and in which direction. Take your time, if you remove the cowl for any reason make sure you refit with all screws in place before doing any more alterations. With the needle valve, again be as accurate in measureing as you can drill a pilot hole and then insert a wire probe to see if it's inline with your needle valve. If you are way off you can refill this hole with epoxy and sand. When your inline with your pilot then drill clearence for your needle. I do not no your engine (Ibut I would imagine a similar proceedure for your choke I hope this all helps. Graham Lee Quote Link to comment Share on other sites More sharing options...
Richard Duvall Posted March 24, 2009 Author Share Posted March 24, 2009 Graham, Thanks for your advice above, especially the temporary rudder band fix - so obvious but I didn't think of it! Apart from resolving the extremely tight fit of my engine, the only problem I am left with is how to attach the extension to the needle valve after the cowl is fitted or how to get the cowl on with an extension already fitted to the needle valve! (choke would be a similar connection). I'm currently wating for the glue to dry on the 2 cowl halves as up till now I've been doing my trial fits with them just taped together in case they needed trimming down at all - they don't! Quote Link to comment Share on other sites More sharing options...
Richard Duvall Posted March 24, 2009 Author Share Posted March 24, 2009 Martin, Sorry I missed your posting at first! Use of allen keys through the air intakes sounds good; I'll have a go later. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted March 24, 2009 Share Posted March 24, 2009 I forgot to say that I don't bother with a choke on my 4 strokes. Assuming you use a pressure pipe then all you need to do is place a finger on the silencer and turn the prop a few times until is sounds a bit sloppy...most 4 strokes (and many decent 2 strokes) will then start on a back flip. Alternatively, get someone to pulse their finger sympathetically (to avoid flooding) on the silencer end while you apply the starter. One less hole in the cowling and I think you'll find it as good if not better than using a choke. Quote Link to comment Share on other sites More sharing options...
Bruce Richards Posted March 24, 2009 Share Posted March 24, 2009 The other option is to remove the needle and have a hole in the cowl big enough to insert the needle, with the extension attached, after the cowl is in place. Quote Link to comment Share on other sites More sharing options...
Graham Lee Posted March 24, 2009 Share Posted March 24, 2009 Hi Richard On my ASP 61 the knurled end of the needle has a drilled hole and a grub screw at the side of it to grip a wire extension. I am taking your engine does not have this, but you will have to extend your needle valve any way you can.You can then put the needle in with the cowl on. Suggestions A female/male connection is req from the end of your needle,perhaps from a brass wire wheel collet or similar containing the required grub screw and a piece of wire centralized (capping the collet with a metal disc) drilled for the wire extension out side the cowling. Soldering the collet to the wire. I have seen a piece of wire attached to a piece of dowling drilled for a tight fit over the knurled portion of the needle. A small 90 bend at the end of the wire in both cases. Similar for your choke if you need it, I agree with Martin on this. If you look at my pics my needle valve comes out level with the out side of the cowl but will req a small extension in use Regards Graham Lee Quote Link to comment Share on other sites More sharing options...
Graham Lee Posted March 24, 2009 Share Posted March 24, 2009 Hi Richard Here's another tip for you to get a good looking back plated spinner fit to cowling When fitting engine & cowling fit a tempory 1/16 piece of solar filmed covered balsa (piece it or hole in the middle) with the film faceing the cowl-between the backplate of the spinner and the cowl. Use resin and micro-ballons around the back of the filmed balsa attaching it to the nose of the cowl. When it sets the resin will not stick to the film just pull the balsa with film away. Sand to the finish that's how I did mine. See pics. Regards Graham Lee Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted March 24, 2009 Share Posted March 24, 2009 With out reading all six pages of this thread I don't know if this has been mentioned but Flying Scale Models from Model Activity Press recently ran the plans of a 1/4 scale Chipmunk. The magazines also included masses and masses of full size detail and superb 3-views. I know they were in the January and February issues and also almost certainly the December issue. I had the Jan and Feb issues and removed the Chipmunk material for possible future use. Back issues are available. Quote Link to comment Share on other sites More sharing options...
Mark Godbeer Posted March 30, 2009 Share Posted March 30, 2009 Hi Richard I am getting near needing to make holes for exhausts and things, so some of the ideas have been useful. I have just used Poly C for the first time, it looks good so far. I had not heard of it until i saw this thread. two local model shops had not heard of it either, they looked at me as if i should have tried a pet shop instead!! I am using it with glass cloth on my Fuselage fin & tailplane. The Wing, Elevator & Rudder will be covered with Solartex. I was lucky enough to get real close to a couple of Chipmunks this weekend, and will even be flying in one soon. It enabled me to get some good detail photos. Heres a pic of me like a kid in a toyshop. first time in a Chippy cockpit since 1976. I think the cockpit has shrunk since then Quote Link to comment Share on other sites More sharing options...
Richard Duvall Posted April 16, 2009 Author Share Posted April 16, 2009 I haven't posted many updates lately, mainly because I'm taking a long time with the painting process and there seems little point in repeating picture at different stages of painting. Updates will follow soon as I hope it will be ready for flying next month! In the meantime I'm stuck trying to identify one of the supplied plastic parts. I can't find and mention of it in the instructions nor see any sign of it on the plan. If any past or present builders of this kit can identify it I'd be very grateful. Quote Link to comment Share on other sites More sharing options...
Chinesespaceman_ Posted April 16, 2009 Share Posted April 16, 2009 Hi Richard, I'll have a look in my box of bits this afternoon and see if I can help. Initial thought - is it the duck tail that goes onto the very rear of the fuselage, extending underneath the rudder? Cheers Gav Quote Link to comment Share on other sites More sharing options...
Richard Duvall Posted April 16, 2009 Author Share Posted April 16, 2009 Spot on Gav - Soon as I got back up to my work room I recognised the shape of the rudder! How's your build progressing? Quote Link to comment Share on other sites More sharing options...
Chinesespaceman_ Posted April 16, 2009 Share Posted April 16, 2009 Hi Richard, I've not got too far lately. Been building a new "Hangar" and rearranging the garage as things wree getting unworkable. Have got as far as finishing the poly-C on the wing and have covered from behind the sheeted area with Solartex. I will take a photo and post it later tonight. Am looking forward to getting onto the fuselage and some progress. I think i have tried to re-engineer / over-engineer the wing to get it more scale like and caused myself no end of problems and probably not got the desired result. Anyway, it's all a learning curve. Catch you soon Gav Quote Link to comment Share on other sites More sharing options...
Hugh Coleman Posted April 16, 2009 Share Posted April 16, 2009 Richard, That's the fairing that sits between the Horisontal Stabiliser and the Rudder. It'll need some trimming. Looks pretty accurate to the real thing actually. Have a look here... http://www.dhchipmunk.com/ Cheers, Hugh Quote Link to comment Share on other sites More sharing options...
Chinesespaceman_ Posted April 26, 2009 Share Posted April 26, 2009 Richard, I am hoping you can help me here. The 5mm sq stringers F19 and F20 - do they both run up and into the F1 Balsa? My F1 balsa has a 6mm sq notch in it and I'm unsure whether thet have just cut this a bit too big, or whether it should be 10mm to take both stringers. I have found that he accuracy of the cut outs in the Fus formers is really poor, when I try to laminate the F2 balsa and ply the cut outs don't match. My F1 ply former has no notches at all, but I think the plan shows stringers going through the F1 ply former. What was yours like? Cheers Gav Quote Link to comment Share on other sites More sharing options...
Richard Duvall Posted April 26, 2009 Author Share Posted April 26, 2009 Gav, No, F19 finishes just in front of F2 - shown with a bevel on the plan. I don't recall having any trouble laminating F2 - have you got them the right way up? F1 Ply should not have any notches in it as it forms the front firewall face into the cowled area. Quote Link to comment Share on other sites More sharing options...
Chinesespaceman_ Posted April 26, 2009 Share Posted April 26, 2009 Hi Richard, Sussed out F19 thanks, I picked it up as you say with a bevel on each end. F1 ply okay then, I just can't be confident with anything in this Airsail kit! The laminated pieces on the wiong centre section were like that in my kit as well, the tooling they have used for my parts is really poor. Anyway, I guess that's the challenge. Cheers Gav Quote Link to comment Share on other sites More sharing options...
Chinesespaceman_ Posted April 28, 2009 Share Posted April 28, 2009 Hi Richard, more questions....... When I fit the stringer F20 as far back as F6 it induces a twist in the fuselage in the direction shown. I guess if it is fitted with the rest of the fus all pinned down to the bench it might come out straight, but I'd rather not have a stressed structure. The position of the slot in F6 forces a sharp downward turn and twist in the stringer. My thinking is to soak the stringer and then fit. I am really questioning if this looks right to you - I haven't put something in the wrong way??? Cheers Gav Quote Link to comment Share on other sites More sharing options...
Richard Duvall Posted April 28, 2009 Author Share Posted April 28, 2009 Gav, I obviously can't look at mine as it is all sheeted in now. But looking at the fuselage in that area the sheeting does have a curve to it so it follows that the stringers beneath must have the same shape. I do have a vague recollection of applying a bit of steam to something and it might have been that so your idea of soaking is in line with that. It does look right. Quote Link to comment Share on other sites More sharing options...
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