Phil Winks Posted June 13, 2015 Share Posted June 13, 2015 Very good indeed I see your going for a trophy here Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 13, 2015 Author Share Posted June 13, 2015 Thanks Martin, Phil. Yep, going that extra mile for another pot Phil! But not really. The Cub is more a build for myself. I didn't want a Cub that everybody else has and it had to be big and STOL plus I fancied the challenge. Aside from tidying a few bits up I've spent most of the afternoon installing the batteries and switches! A while ago I read a thread on here about retract servos stalling out and draining the RX battery causing the loss of the model and decided that wasn't acceptable to me. I installed a separate retract battery in my Corsair after that and with the Cub having high power digital flap/slat servos it will also need a separate battery in case the mechanism binds up. First job was to cut and install a ply plate to velcro the batteries to so they won't punch through the floor on a hard landing. A bracket was made from 1mm ply and 1/4 sq balsa to fit the two switches into and fixed to the inside of the cabin. The RX battery is a 6v 2600mah (for Spektrum RX) and the aux flap/slat/lights battery a 4.8v 2400mah I soldered up a three way adapter for the aux battery, cut the live wire for the flap/slat servos and soldered it to two lives from the adapter. The third live (and neutral) have a male servo plug to connect the light module to. I then cut the live and signal wire from a scrap servo lead and soldered the two remaining neutrals to it to plug into the last remaining socket on the RX to complete the aux circuit. It doesn't sound like much but it's taken most of the afternoon labeling connections, routing cables, soldering, heatshrinking joints and quite a bit of thinking & checking to avoid blowing up the RX or lights! Next up are the wing servo hatch covers, U/C covers and connecting the steering to the tail wheel then I can make a start on masking and painting! Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 14, 2015 Author Share Posted June 14, 2015 This evening I made the servo hatch covers for the wings. Started by making triangular fillets from scrap ply. These were glued into the corners and then a sheet of 1/16th ply cut to cover the hole. Unfortunately the aileron pushrod Z bend was rubbing on the hatch so I had to raise the servo by 3mm. A hole was cut for the servo spline to poke through. These just need sealing & painting now. I also made the U/C covers tonight. I used some card to make a template and then cut them out of 1/16 ply. I used 1/8 X 1/4 Spruce strips to reinforce the back and to form channels for the U/C wire to sit in. The covers were drilled & fitted with metal U/C straps fixed with M2 nuts & bolts. The excess bolt will be trimmed off when I remove the U/C for sealing and painting. Cosford airshow tomorrow so I won't get started until early evening but I hope to get those shock absorber covers made and some bits sealed and painted! Edited By Chris Barlow on 14/06/2015 01:34:44 Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted June 14, 2015 Share Posted June 14, 2015 I flew my old BH Cub a few days ago, and had the u/c covers on. Reckon they look good and Chris decided to make them for his. - which reminds me - one needs to be glued back on... Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 14, 2015 Author Share Posted June 14, 2015 Yep. Despite this not being a scale replica I think they're going to be vital to the Cub "image" Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted June 14, 2015 Share Posted June 14, 2015 Nice work as always Chris John Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 16, 2015 Author Share Posted June 16, 2015 Thanks John. Started painting last night so will have a bit of an update this evening. Not long to go now!... Quote Link to comment Share on other sites More sharing options...
Martian Posted June 16, 2015 Share Posted June 16, 2015 excellent neat work Chris Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 25, 2015 Author Share Posted June 25, 2015 Paint, paint and more paint! With a fishing trip and Weston Park I have had 4 days off but other than that I have been masking, priming or painting nearly every evening but it's nearly there! The cowl has been sprayed with 2 coats of high build primer, sanded with wet and dry, primed again and sprayed tonight with its second coat of white. This will be flatted down with 1200 grit wet and dry before a final coat of paint! The wings have been painted on the underside with 2 coats of Yellow and 2 coats of the colour scheme on the top. This will be lightly sanded with 1200G to redece the masking lines before a final coat of clear gloss. I also managed to get the registration done for the fuselage. I have gone for a Canadian registration as the inspiration for the Super cub was the Tundra STOL Cubs flying in Canada. I could have gone for an American registration but the US format limits creativity! Started with a jumble of vinyl letters. A strip of 2" masking tape was stuck down sticky side up and a base line marked on it... The letters were then carefully removed from the backing onto a scalpel and positioned sticky side up onto the masking tape. When complete and lined up the whole assembly was transfered to the fuselage. The masking tape was then peeled off leaving the letters behind. A couple had to be encouraged to leave the masking tape by holding onto the fuselage with a scalpel. And the final registration. This will be sealed with an extra coat of clear gloss to aid adhesion and prevent peeling. Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 28, 2015 Author Share Posted June 28, 2015 Painting and a clear coat of fuel proofer finished. Cowl came out OK. Glazing was done last night. I made card templates of all the windows before cutting them out of 40thou acetate sheet and fitting with canopy glue. They're a bit thick and heavy but crystal clear! Tail flash... Magnet added to cockpit glazed door to hold it open And cockpit roof glazed Even managed to get a sticker on it! Now a few things to finish off and tweak the controls and CG then ready for a maiden hopefully tomorrow night. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted June 28, 2015 Share Posted June 28, 2015 Looks fantastic Chris, I doubt the maiden will be any big deal for you, apart from a big grin. John Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 28, 2015 Author Share Posted June 28, 2015 Should be OK until I hit that flap switch... Quote Link to comment Share on other sites More sharing options...
Phil Winks Posted June 28, 2015 Share Posted June 28, 2015 Then the flap starts eh Chris seriously though looking good mate edit: Do you not have to wait a week or so for the fuel proofer to cure completely??? Edited By Phil Winks on 28/06/2015 20:43:28 Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted June 28, 2015 Share Posted June 28, 2015 Looks good, Chris. Also bought that 2 1/2 inch spinner you wanted for the Cub. Hopefully I will see the maiden some time this week... Quote Link to comment Share on other sites More sharing options...
Martyn K Posted June 28, 2015 Share Posted June 28, 2015 That looks absolutely superb Chris. Beautiful Well done Martyn Quote Link to comment Share on other sites More sharing options...
Martian Posted June 29, 2015 Share Posted June 29, 2015 Cracking job Chris it looks superb Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 29, 2015 Author Share Posted June 29, 2015 Thanks guys. Still to many bits to fettle to commit to the flying field so no maiden tonight. Phil yes the fuel proofer should have a week the cure (and I would recommend leaving it as long as possible) but I have found through impatience that as long as it's left a minimum 3 days, as for overcoating, and exhaust efflux is cleaned off properly after flying it seems to get away with it! The underside of the fuselage was sprayed on Friday evening whilst up side down but the sides and top were sprayed Saturday afternoon so they might still be a little "green" Quote Link to comment Share on other sites More sharing options...
Martyn K Posted June 29, 2015 Share Posted June 29, 2015 What did you use for fuel proofer Chris? Edited By Martyn K on 29/06/2015 19:08:57 Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 30, 2015 Author Share Posted June 30, 2015 Martyn, I used Spectra clear gloss fuel proofer. I will be re-covering a Tiger Moth later this year so might try something new. Tonight I finished off a couple more bits. Just the little details that will keep it from plummeting to the ground! Checked the radio and control surfaces for binding, range and direction again. Also checked the flap/slat operation to make sure no varnish has got into the slides to make them sticky! Last check was the failsafe again, which had reversed and sent the servo to full throttle! When I installed the RX and set up the sevos the throttle servo had to be reversed so I reset the failsafe by re-binding the RX. I have checked the correct operation several times during the build by deliberately turning off the TX first. I'm not sure why it has reverted back to full throttle but I will be watching out for that in pre flight checks and am quite glad it didn't happen with the engine running! A simple strap was made to secure the fuel tank.. The U/C bungees were bound with red nylon to prevent them from slipping off the anchor point and to ensure all the strands work together. Still have to make the boots to cover them yet. I also tested the fuel tank for leaks by filling it through the filler valve and found I had connected the pipes the wrong way round! The only recourse was to remove the cowl, take out the valve, swap the pipes over and refit the cowl again! Glad I wasn't at the field for that one! I also fitted the Alloy spinner Paul brought back from Wings 'n Wheels which took a little fettling with a dremel to clear the prop. Now it really is ready to fly (hopefully tomorrow now) I have still to fit bracing wires to the tail plane, fit boots to the u/c, make an instrument panel and fit a pilot & seats but with less than 2 weeks to go I need to know if there are any flight problems to sort out first! Edited By Chris Barlow on 30/06/2015 00:34:06 Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 30, 2015 Author Share Posted June 30, 2015 Oh and checked the CG which was 80mm from the leading edge. It should be 85-90mm so with the tail bracing it should be spot on with no additional tail weight. Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 30, 2015 Author Share Posted June 30, 2015 Took the Super Cub out for a visit to the field tonight. The wind was a bit gusty but absolutely 90 degrees to the strip! Built her up and performed a range check, full control and direction check (again) Fueled up and check for leaks Then took the Kunai up for a spot of thermalling whilst hoping the wind might die down a bit! It didn't! Still, we ran the engine up and set the throttle range on the TX, check the throttle cut then re-fuel, re-start and taxi out to the strip! Crosswind or not tonight was the maiden! Pointing diagonally down the strip and with Paul next to me as my trusted backup I opened up the throttle. The tail popped up almost immediately due to the plane still being slightly nose heavy so a little back pressure on the stick and she was away! Quite a bit of up elevator and a click or two of left aileron and she was flying nice a straight despite the bumpy thermals and wind! Quite fast too so I reduced the throttle to just under 50% for cruising around! Ailerons were very responsive with almost the correct amount of differential, needing just a little rudder in the turns to keep her looking neat. Now I wouldn't really have tried a maiden in tonights conditions but being a David Boddington design, and a Cub, and looking at the wing section and area I wasn't too concerned about a regular flight. Until Paul suggested gaining some height and trying the flaps. So back to 75% throttle and a little elevator and she climbed away nicely, probably to nicely because due to the size she was actually quite high up! I turned her into the wind so she was pointing away from us and reduced the throttle to almost idle and let the speed die off, then deployed the first stage flap/slat. Nothing. Due to the height we couldn't see if the flaps were down or not but she wasn't ballooning up, rolling over or dropping into a spin. But she wasn't coming down either even with the engine just above idle. Not sure if the flaps/slats were deployed, stuck or I'd hit the wrong switch we tried full flap... This time there was a noticeable nose up change, corrected with a little down elevator, but really not much. I suspect the slats are creating lift at the front of the wing and the flaps lifting the rear of the wing almost equally. Deciding there were no nasty surprises in store I increased throttle to 50% and reduced the flap to zero, lowering the nose at the same time just in case. A descending circuit later she was at a more normal height so I tried half flap again. This time we could see and the flaps were hanging down nicely with a slightly pronounced bump at the ends of the leading edge of the wing where the slats were poking forward. And still no change in pitch! A full circuit at first flap and I called a landing. Edited By Chris Barlow on 30/06/2015 23:02:09 Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted June 30, 2015 Author Share Posted June 30, 2015 The landing approach was quite long with first flap with the intention of having loads or room to scrub off the speed. Being a maiden I was quite prepared to abort and go around a couple of time until I got the landing speed right but with about 50' to go to the threshold the engine cut! No problem as I was already lined up with the other side of the strip expecting the crosswing to push me across to the center line so I lowered the nose and carried on. Maybe it's due to the 8.8lb weight but the wind didn't push her across anywhere near what I expected so using rudder and aileron I slipped her sideways to the correct line but she was still quite fast. If the engine had still been running I would have throttled up and gone around but that was no longer an option, and she was now over the threshold about 15' high. Since full flap is set to nearly 80 degrees I was expecting them to create a lot of drag so deployed them knowing I needed down elevator at the same time, which was good because down was what I needed! Unfortunately despite a very nose down attitude she was maintaining height down the strip although the speed was dropping off. At the end of the strip she was about 3' high and just clearing the long grass, but now very slow. I saw her sink a little so reduced the down elevator to a little up and she flared a little then came down with what could have been a nice three point landing, if she were still over the strip! As normal the grass snagged her and pulled the nose down but as the speed was extremely slow that was about it. Paul retrieved her from around 10' past the end of the strip and a carefull inspection revealed no damage and still about a quarter of a tank of fuel. Further running of the engine revealed it was getting a little hot so baffles to close off some of the air inlet holes and to direct the air over the crank case were planned. Despite the deadstick and overshoot I was comfortable with the flight and had the engine not died I know I would have gone around a couple of times until the landing speed was good so I'm quite happy to class this as a successful maiden and the Super STOL Cub has now graduated to a flying aeroplane! (and subsequently gets a picture) Edited By Chris Barlow on 30/06/2015 23:05:10 Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted July 1, 2015 Share Posted July 1, 2015 Nice work Chris, good debrief as well John Quote Link to comment Share on other sites More sharing options...
Martian Posted July 1, 2015 Share Posted July 1, 2015 well done Chris excellent Quote Link to comment Share on other sites More sharing options...
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