Danny Fenton Posted June 22, 2016 Author Share Posted June 22, 2016 Hi Tony, sorry I didn't address your point about the hinge bearings. Bushing like this has been done for decades and is normal practice. If the model and hinges were bigger then it might be an issue. Denis Bryant specifies formica as the material from which the hinge parts are made, and yes he suggests small screws as the hinge pins. Even at 1/4 scale Dave Womersley does it this way too. His hinge brackets are from alloy, but the bearings are still screws. So although I appreciate your engineering concern about using a thread as a bearing surface, from experience it works just fine in this instance. Cheers Danny Quote Link to comment Share on other sites More sharing options...
Richard Steane 1 Posted June 22, 2016 Share Posted June 22, 2016 I've been reading the posts about hinge screws and thought that I would mention my solution to the problem by making a "shoulder screw" a photo of which I posted in November last year. This is a standard engineering solution to this kind of simple mechanism but is of course only possible if you have a suitable lathe. Progress on my Chippie is still stalled due to extension building work and will not resume until the new floor has been underboarded and the workshop becomes a safe environment for model aircraft. Cheers Richard Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted June 23, 2016 Author Share Posted June 23, 2016 Hi Richard, and a great solution it is too.. My point is however, that I think the normal bushed hinge will outlast the model so is all the extra work warranted? Anyway it only took a couple of hours to bush my wing hinges so i am closer to the maiden now. Just need to address the prop issue...... Cheers Danny Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted June 25, 2016 Author Share Posted June 25, 2016 Quite pleased, managed to carve a flying prop, looks very similar to the static prop! Static prop was whittled from a scrap piece of pine, the flying prop is maple. Full process shown in September RCM&E Cheers Danny Quote Link to comment Share on other sites More sharing options...
michael goddard Posted June 30, 2016 Share Posted June 30, 2016 Hi Guys. Just reading your build blogs on the chippie, (Very interesting0 build and have got to the bottom of page 21. The question is has it got washout? Interesting question as I`m building a 1/5 scale 82in wingspan model designed by Roger Pegg and John Kidd and they suggest a 3% progressive washout with Flaps and Ailerons built in the wing and then cut out after top of wing has been completed. There is and article about the build in the June 1994 issue of Radio Modeller. Cheers Mick G Quote Link to comment Share on other sites More sharing options...
Tony Smith 7 Posted July 7, 2016 Share Posted July 7, 2016 I think it was mentioned during the wing build, unfortunately I don't think you can search a thread so might be a matter of working your way through. It's a good read though. Quote Link to comment Share on other sites More sharing options...
mickmatt Posted July 10, 2016 Share Posted July 10, 2016 Hi Danny, Just a couple of questions, Have you flown your Chipmunk yet ,either with wires or wireless and also what motor did you fit, make and model would be interesting. Thanks in advance Mike Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted July 10, 2016 Author Share Posted July 10, 2016 to be honest I cannot recall if the wing has washout or not, I do remember there was a lot of discussion and some were going to increase it? Personally I have built it as per the plans. The model reportedly flys very well, and at 6lbs the wing loading is very low. Hi Mike, no the Chipmunk hasn't flow in either mode yet, though it is ready. I took it along to Greenacres this weekend and perched it by the Tx tent, so that people could see it. I ended up with three things broken on it, and nobody came up to me to chat about it, so I shall keep it safe at home from now on, my models only seem to suffer when I take them to show people..... I have decided just for the maiden to swap the wheels and stiffent the oleo, that way I can fly off grass, as tarmac is proving illusive. Cheers Danny Quote Link to comment Share on other sites More sharing options...
Andy Muckley Posted July 11, 2016 Share Posted July 11, 2016 Hi Danny sorry to hear that there was damage and i missed the chippy on display, i would have liked to have sen it again, but probably best kept out of harms reach Quote Link to comment Share on other sites More sharing options...
John Timmis Posted July 11, 2016 Share Posted July 11, 2016 HI Danny Sorry to hear that the Chippy was damaged , that really is very irritating for you. I do hope to see it again sometime in the future. Holidays & family activities have kept me away from Greenacres & Western Park this year; Cosford too is looking more than a bit iffy. It would be good if we could manage a ' Chippy survivors' gathering at some time for photos & a natter. I've been trying to take some flying photos of the Chippy but have not managed to get anything worth posting yet. Re the washout . Mine is built as per plan. Weight is 8 3/4 lbs, so not a lightweight. In about a doz flights it has been fine. But keep a safe speed on for landing & take care not to spin off the final turn. Cheers John. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted July 11, 2016 Share Posted July 11, 2016 A few weeks ago I tried to get to grips with my Chipmunk build and made some rapid progress, but since then I had to complete a substantial rebuild on the Seafang caused by my own piloting incompetence, then family holiday commitments plus some heavy professional issues have stuffed it completely. This week I am self-indulging on a six day break booked months ago in the Isle of Man for the Southern 100 races, on my motorbike. I get back on Friday, then on Monday I have been caught for jury service, four weeks away from my 70th birthday. Someone's out to get me. I'll get back to it as soon as I can. The real Chipmunk has got wash-out. I have put three degrees into mine. As this reduces the average incidence by 1.5 degrees, I have increased the root incidence by 1.5 degrees to compensate. It's surprising how much alteration you have to make to achieve that. I'm a strong believer in wash-out, I think it makes for a more efficient wing apart from addressing the tip stalling issue, but that's just my opinion. Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted September 14, 2016 Author Share Posted September 14, 2016 Well chaps my Chipmunk has flown. It was a bit blowy, but straight down the strip. I was warned that there seemed to be an area of sink right at the threshold of the runway, so I mentally intended to land further along the field, but of course I hit the sink and ran out of elevator. I didn't hit the ground but I also didn't get much of a flare. The speed, though not excessive, pulled the leg and the block loose on one side! I needed a great deal of up trim, which could be incidence issues, but I am tempted to try moving the c of g back a little, and increase the elevator throw. Anyway it flew really well, nicely balanced in the turns without needing much rudder. Apart from the U/C issue very pleased. Cheers Danny Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted September 14, 2016 Share Posted September 14, 2016 Congratulations with your maiden, Danny. I just hope for you that the u/c 'trouble' isn't really major. Great build, sir. Do you realize that following your build blog since nearly the beginning, made me decide to participate to the Ballerina Mass Build with, of course, not the most single clue what I was doing... Thank you for your inspirational posts, Danny. Hakuna matata Chris BRU - BE / CTR WP912 Control Edited By McG 6969 on 14/09/2016 20:51:30 Quote Link to comment Share on other sites More sharing options...
AndyD Posted September 14, 2016 Share Posted September 14, 2016 yea congrats on the maiden,ive been waiting for this, looks a lovely flyer ,i blame this build thread for ending up with the big and small BH chipmunks, Quote Link to comment Share on other sites More sharing options...
Fatscoleymo Posted September 14, 2016 Share Posted September 14, 2016 Great to see it fly Danny....l must get mine finished.....ready for next season. Well done..and thanks for the inspiration.. Fats Quote Link to comment Share on other sites More sharing options...
John Timmis Posted September 14, 2016 Share Posted September 14, 2016 Danny Congratulations on the first flight. Good to get that over & out of the way. Hope you're set for very many more now. It's a lovely model. Shame about the undercarriage, hope it's not to serious. Cheers John. Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted September 15, 2016 Author Share Posted September 15, 2016 The damage is not too serious but will mean hacking the wing open, and if this side failed so will the other, so they will both need attention. The repairs and strengthening probably wont be too difficult, the problem will arise trying to hide the repairs I think I have made the undercarriage less forgiving by using solid oleos rather than springy piano wire. The torsion arms should have worked here but perhaps minus the springy legs the load is to sudden. I am sure it would have been okay on tarmac, but on grass the drag on the wheels was too great. So if you haven't covered your wings yet it might be an idea to bolster this area? Cheers and thx for all the positive comments, they are much appreciated Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted September 15, 2016 Share Posted September 15, 2016 Congratulations on the flight Danny, clearly once the undercarriage is sorted you've got a reliable flyer here. I don't think that wire legs would have prevented this. The sudden bending motion is focused at the point where the leg goes into the wing and then translates into a torsional twist that ends up at the anchor point in the wing. Clearly the damage has been minimised by the design doing its' job, the problem is that it's a fairly flimsy structure without a lot of tolerance for events like this. It worried me from the start and mine is beefed up here, so fingers crossed. Mine is waiting for me to finish off the wing root fairings, once that is done the remaining work is covering, finishing and cockpit detail. All of the motor installation work, (except for exhaust) and radio/servo installation is done. I need to take a big gulp of fresh air and get stuck into it. Too many other things have got in the way this year, but it will happen. I'm hoping that the alterations I made including the undercarriage reinforcement, scale wash-out and hopefully some structural lightening will help, although it is possible that with the four-stroke up front and lighter structure behind the wing, the battery will need to go well back to get the c of g right. We'll find out. Quote Link to comment Share on other sites More sharing options...
Terry Walters Posted September 15, 2016 Share Posted September 15, 2016 Well that was nice news to start my day today! Well done Danny - looks lovely! I'm sure you'll sort the u/c out with your usual high standard! Terry Quote Link to comment Share on other sites More sharing options...
Martyn K Posted September 15, 2016 Share Posted September 15, 2016 Fantastic - Well done Danny. It looked great in the air and very smooth as well Perhaps CG go back a bit? Would help with the flare out. Sounds like you ran out of Elevator Martyn Quote Link to comment Share on other sites More sharing options...
stu knowles Posted September 15, 2016 Share Posted September 15, 2016 A bit of a sickener to have to cut into all that beautiful surface detail though.. Since I moved over to petrol model which don't spray oil over everything I have taken to test flying a bare and basic airframe as soon as the covering is applied. Not only does it give a boost to the remaining stages of the build it does give an opportunity to discover any issues before the final finish is applied. Its been a brilliant thread though, Thanks Danny, I've picked uploads of good stuff. Edited By stu knowles on 15/09/2016 09:20:50 Quote Link to comment Share on other sites More sharing options...
Richard Steane 1 Posted September 15, 2016 Share Posted September 15, 2016 Brilliant to see your chippy fly after all this time Danny. It must have been nerve racking but the low passes for the camera were great. The undercarriage damage is clearly at the anchor point to the rib and I don't remember if you followed the plan and used the single screw and clip or did something else. I was concerned about this and have anchored mine into a hole in a beech block that is then glued and screwed to the rib. Although I have sheeted over this area I could of course rework this (although I'm not sure how) once I get back to the build when my workshop is finally reinstated. Cheers Richard Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted September 15, 2016 Share Posted September 15, 2016 It's an absolute cracker and really does look almost real in the air. Well done Danny, another good milestone. Quote Link to comment Share on other sites More sharing options...
Nigel Day Posted September 15, 2016 Share Posted September 15, 2016 Looks a beauty Danny, well done. You can't fool me though, I bet you're really looking forward to redoing some of that detailing around the U/C. Quote Link to comment Share on other sites More sharing options...
Andrew Price 2 Posted September 15, 2016 Share Posted September 15, 2016 What Nigel said! Quote Link to comment Share on other sites More sharing options...
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