john stones 1 - Moderator Posted May 14, 2015 Share Posted May 14, 2015 That looks well Chris, will it be an on board glow or will you cut the cowl ? John Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted May 14, 2015 Author Share Posted May 14, 2015 Thanks Martian. Did you see what I meant about the slats? I was hoping to get some ideas from the other builds but you & Martyn have used fixed slats and Ian has had to cancel his build so I've had to make it up as I went along! Just hope they work OK. John I have an auto remote glow I can use or just a remote for the stick. I am tempted to use the auto because that might aid throttle pick up from idle a bit more? Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted May 14, 2015 Author Share Posted May 14, 2015 Phil, treated myself to a new folding bench this week! Finally found some in stock near me! Quote Link to comment Share on other sites More sharing options...
Martian Posted May 14, 2015 Share Posted May 14, 2015 Yes I did Chris you did a lovely job with your slats and flaps actually excellent is a better word, on mine the slats on the full size are fixed and work by AOA ,I've seen some videos of the Zenith and Cubs in action their short distance take off and landing is incredible although they have different methods, look at this world record holder in what looks like a Cub Quote Link to comment Share on other sites More sharing options...
Martian Posted May 14, 2015 Share Posted May 14, 2015 Zenith STOL comp Quote Link to comment Share on other sites More sharing options...
Phil Winks Posted May 14, 2015 Share Posted May 14, 2015 Posted by Chris Barlow on 14/05/2015 17:33:02: Phil, treated myself to a new folding bench this week! Finally found some in stock near me! Nice one Chris you'll soon be wondering how you did without it Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted May 17, 2015 Author Share Posted May 17, 2015 Thanks for the links Martin that's exactly what I aiming for. Something that'll take off in 8' and land at a walking pace! The competitions held at Valdez were my inspiration for this Cub! Time for an overdue update I think! The elevator torque rod has been made with 12g wire with a brass horn soldered on the centerline. This means the elevator pushrod will be retained inside the fuselage and hopefully always operate the controls evenly! The pushrod was made the trad way with 1/4 dowel and wire but bound with 100lb fishing braid & cyano! I noticed there was a bit of twist at the tail and with the airframe still a little nose heavy decided to stiffen up the rear fuselage with cross grain 1/16 balsa to the bottom and braid bracing "wires" down the fuselage. ...and installed tubes for the rudder cables to exit the fuselage. The tail and fuselage were then covered with white solartex. White tail light wired up and installed... And rudder control horns & tail wheel. Due to my rubbish eyesight (well that's my excuse) the underside of the wings and tail are covered in yellow tex. This is almost semi translucent so will have a coat of Cub yellow paint before the final clear fuel proof varnish. Red fuselage beacon installed... ...and finally a quick look down inside the fuselage at that wire bracing again. This has removed almost all the twisting motion at the tail end on its own with almost no additional weight! Quote Link to comment Share on other sites More sharing options...
Martian Posted May 17, 2015 Share Posted May 17, 2015 Lovely neat work Chris Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted May 17, 2015 Author Share Posted May 17, 2015 More progress this afternoon, I covered the wings! Really doesn't sound like much but each wing has taken approximately 5 hours! Each of the horns on the torque rod were drilled with a 1mm pilot hole through into the carbon tube, opened up to 2mm then finally 2.4mm and threadded with an m3 tap. These holes were then filled with an m3 grub screw. I really don't want these horns to be able to rotate on the tube once the wing is covered! Next each of the control surfaces were covered, 3 per wing half. The underside of the wing was then covered along with the top of the "D" box. Once covered the slat was inserted back into the wing and reconnected to the pushrods. Again I don't want anything coming loose under the covering so after the clevises were adjusted to fully and equally retract the slat they were secured with a locknut and piece of fuel tubing. Finally the top of the wing was covered and the flap and aileron hinged with tex and connected up. Then I started again with the other wing half! The cub is getting a bit big now so assembled photos have to be taken outside. I can assemble it on the bench for testing & setting up but can't get far away enough to fit it in a photograph! So whilst there was still enough daylight she was assembled on the lawn. Grass still needs cutting! Covered slats extended... And flaps fully deployed. Still to do are covers for the servo hatches, wing struts, glazing and a cowl. The engine is on hold whilst I reconsider the options. A 2 stroke as originally planned will give the rpm and power required but I just know I'd prefer the sound of a four stroke when cruising around. The more I think about it the more I think I'd prefer a .91 four stroke! Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 17, 2015 Share Posted May 17, 2015 Can't argue with your engine thinking and can't fault your building either Soon be done Chris, then the glazing to do John Quote Link to comment Share on other sites More sharing options...
Martian Posted May 18, 2015 Share Posted May 18, 2015 she's looking the business Chris I look forward to seeing it at Greenacres and the pink passion of course Quote Link to comment Share on other sites More sharing options...
Martyn K Posted May 18, 2015 Share Posted May 18, 2015 Looking absolutely great Chris. Is there a photo around of the full sized that you are modelling this on? I like the colour scheme Martyn Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted May 18, 2015 Author Share Posted May 18, 2015 After much consideration over the last couple of weeks I have decided to go with a .91 four stroke so last night I did a quick shopping trip to HK and ordered a new engine! ASP FS91AR £109.00! I just know I would quickly tire of a two stroke gurgling on near idle for slow fly bys! Martyn, there isn't really a full size this is based on. A lot of the planes used for the STOL comps are custom jobs. I was initially planning on blue and orange for the colour scheme but realised when flying my Harvard in yellow trainer colours that yellow is much easier to follow. At the same time I didn't want to do it all yellow like a J3 and decided on white for the fuselage & wing tops in keeping with a factory Super Cub. I will probably add trim lines in blue or red to break up the plain covering and to seal the edges on the wings. Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted May 18, 2015 Share Posted May 18, 2015 Yeah! Quote Link to comment Share on other sites More sharing options...
Phil Winks Posted May 18, 2015 Share Posted May 18, 2015 Thats looking great Chris, good to see you've got your priorities sorted models V gardening, models must win every time Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted May 19, 2015 Author Share Posted May 19, 2015 Thanks Phil. Yep there'll be plenty of time to cut the grass after the maiden! I don't know if I'm working very slowly, being too particular or just doing the jobs that take a bit of time but tonight I spent the best part of 4 hours making a wing/jury strut for one side! After a little deliberation on choosing a suitable material for the struts I settled for 3mm ply. The struts were cut with a balsa stripper making several passes from each side. Reinforcing plates were cut from 0.8mm epoxy sheet and a 25mm long off cut of pushrod for the threaded adjuster. A 2mm hole was drilled into the end of the strut, the pushrod inserted with cyano and the plates glued either side with cyano again. When set the epoxy plates were filed flush with the strut and the pushrod threaded with an m2 die. A ball joint was then screwed onto the end of the strut, like so. The pre installed spruce blocks in the wing were drilled out to 1.5mm and the ball joints screwed down. Washers under the joints prevent the balls from crushing into the spruce and binding the plastic against the wing. The fuselage ends of the struts were then cut to length and the angle marked on the rear strut. The angle was cut and the two struts joined together with an epoxy plate either side. With the two struts now joined together the position of the jury strut was marked and short lengths of nylon tube were bound to the struts with braid and cyano. An offcut of pushrod was used to keep the bearing tubes in line with each other. A pushrod was then bent to shape, cut to length and the cut end threaded and an m2 clevis screwed onto each end. 2 epoxy plates were cut and drilled to fit the clevises and inserted into slots cut into pre installed 3mm liteply plates, fixed in with cyano. Still got the fuselage mounting to do but after 4 hours This is how far I got! Tomorrow night I get to do the other side! Hopefully it won't take as long! Edited By Chris Barlow on 19/05/2015 01:26:22 Quote Link to comment Share on other sites More sharing options...
Martian Posted May 19, 2015 Share Posted May 19, 2015 lovely stuff Chris,I agree it seems a disproportionate amount of time is taken up doing the struts I have yet to do mine , oyu have streaked ahead of me now Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted May 21, 2015 Author Share Posted May 21, 2015 The other wing didn't take quite as long to make the struts although the struts themselves were already made, just needed fitting! So with the struts done and an aluminium strip made for bolting to the floor to connect the struts to the fuselage it was time to face the inevitable! The cowl. A few phone calls around and a search of the internet didn't produce any suitable cowls, or anything close enough as second best so it meant I had to make one! I started with some pink floor insulation, 50mm thick. Three pieces were glued together with PU to make a block 150mm X 160mm X 200mm which was shaped with a saw, rasp and sandpaper until I had the shape I wanted and which would accommodate the change of engine to a four stroke. The chin intake was shaped to house the rocker cover so hopefully all the engine will be inside the cowl. So far no photos because my HUDL was on charge and I was on a roll! Now I had a pink foam blank I had to decide whether I was going to make a negative mould in plaster and laminate that in GRP or try a lost foam method which I have tried before years ago, and made a mess! Having followed Peter Garsdens lost foam Tornado I decided to give it another go. The foam blank was wrapped in yellow packing tape and the first layer of tissue and resin applied. The chin was reinforced with an extra layer as the majority of the front will be cut out. After the first layer had set and lightly scratched/sanded a second layer of tissue was applied. This was also scratched to provide a key then a third layer, this time 54gsm glass cloth was applied. After the final layer was set the bigger hollows were filled with body filler and the whole cowl sanded smooth before a final thin coat of resin applied. After washing my hands and taking the HUDL off charge I managed to get the first photo! Ready for the fun part! Dissolving the plug! I opened up a circle through the tape at the back of the plug and poured in a small amount of acetone... Nothing! A test piece revealed this pink foam wasn't reacting to acetone at all and it was just sitting on the surface like water! I do know however that it does dissolve with petrol (We turned a young labourers moped upside down on a sheet at work to fix the bike and spilled petrol on the sheet, which over the course of 10 minutes turned into a puddle of pink goo! So a slight change of plan and I tried again with petrol! That's more like it. Hopefully, and with care the packing tape will stay intact & all the goo will come out in a yellow bag... and leave behind a nice clean GRP cowl. This was rushed inside the house & given an instant bath of clean cold water to remove any of the foam/acetone/petrol mix that might have got onto the GRP. Although thin and light it's quite rigid but will require some additional GRP to the inside to reinforce mounting areas and cutouts. And finally, a quick assembly to see if it fits the nose of the cub and what it'll look like. That's it for now, Time to pack the caravan with planes and family for a trip to Greenacres! The GRP will be well cured by the time I get home! Quote Link to comment Share on other sites More sharing options...
Jim Mchugh Posted May 21, 2015 Share Posted May 21, 2015 Just a stunning build log! Who said blokes can't multitask.... Can't wait to see the Mosquito... Greenacres will be ready for you. Bacon butty at 9:00 AM tomorrow morning then field prep and setup... Edited By Jim Mchugh on 21/05/2015 21:22:37 Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted May 22, 2015 Author Share Posted May 22, 2015 Thanks Jim. Should have the Mossie with me this weekend along with the Atom. Just the Cub missing from the set! Awesome job by the GMAC team to clear the site so quickly! Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 12, 2015 Author Share Posted June 12, 2015 Little progress over the last couple of weeks due to flyins at the weekends but now begins the big push to get it finished, painted and flown! Cowl test fit with the engine installed. The rocker cover fits nicely inside the scoop... and big cooling cutouts should keep everything running sweet! Holes for choke and idle adjustment... Fuel tank re-fitted after changing the engine mount, and fuel pipes in position. I treated myself to a 90 degree adapter to keep the silencer tight to the cowl and closer to the centre line. Throttle linkage & snake installed... ...and connected to a servo inside. More later as last night I made a start on the glazing but the Hudl was flat again! Hopefully I'll start getting some paint on her this weekend. Quote Link to comment Share on other sites More sharing options...
cymaz Posted June 12, 2015 Share Posted June 12, 2015 Chris, big cooling cutouts is not necessarily a reciepe for success. Baffles inside the cowl forcing the air onto the engine and the old rule of thumb, 3x exit to that of entry area, are worth looking into. Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 13, 2015 Author Share Posted June 13, 2015 Not really planning on needing baffles but I have considered making up a dummy boxer engine to fit behind the cowl, or at least mesh over the holes! A few more updates on progress so far. The door window was added by hinging from the top with solar tex Magnets added to the door which close onto metal plates fixed inside the cabin A couple of cut down coffee stirrers used to hold the window closed behind the door and one more to make the handle to open it with. Roof hatch has also been made with cutout for glazing And windscreen glazing also cut and test fitted from a card template Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 13, 2015 Author Share Posted June 13, 2015 With the windscreen fitted it was possible to mark it's position on the bonnet. My wife went shopping for me today and picked up some more building materials. Funky Felt Sheet! This was used to create a flocking effect behind the windscreen inside the cockpit. The bracing bars were also added. Finally tonight the wiring was tidied up and labeled and a plug soldered to the tail marker light. Quote Link to comment Share on other sites More sharing options...
Martian Posted June 13, 2015 Share Posted June 13, 2015 excellent Chris Quote Link to comment Share on other sites More sharing options...
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