Brent Posted September 8, 2014 Author Share Posted September 8, 2014 In reply to levantor3.... I am going with stainless steel for its strength, polishing the weld up after is not a problem, I do recall Paul having buffing equipment he uses to polish his own welds and also has a large selection of cutting pastes in his workshop. Also mild steel is actually not as easy to get as stainless in the sizes required. im going to stick to the tried and tested method so the project does not fail because a lot of money will be invested into this model and I did ask Paul if mild steel would be better but he said just stick with stainless steel so that's what im going to do. Pavalo the original designer of his 1/4 scale cub that is the owner of the cub in the photo on the first page mentioned the paint used I just forget what it is so il have to go and check later. he also mentioned an acid bath before painting which shouldn't be a problem because I do recall my local powder coater doing the same thing on my motorbike frame after paul repaired the crack. that too was aluminium and highly polished and when it came out it was dull. I didn't see the process after that because I left but would have loved to see how he did it. KC I agree, the drawings I have are of the full size cubs framework but certain tubes have been removed from the drawing so as soon as iv put those tubes back in the correct place and removed the additions il be able to measure that drawing via adobe reader at 100 percent zoom and using its built in measuring tool. Martin I understand there's very little difference between the j3 and super cub, am I right in saying that some super cubs had wheel spats fitted? I am almost sure some did and it makes it look even cuter in my opinion and would be tempted to model the super cub. Thank you for the link I will have a good read later, shame there's no pictures of what parts it is describing for replicating them but amore then sure I can find what I need on Google images unless someone has close up photos of a walk round of a cub. allot of things can be found on the net but sometimes close ups of a certain area can be a pain in the a$$ to find and when you do find them they are usually too pixelated to use it as a reference photo. I wouldn't however like to plumb a tank into the wing and have such a long fuel pipe to the carb it screams out trouble to me. thought would be nice to plumb a wing tank into the main tank that can be isolated if needed. but maybe I am just being too ambitious ha-ha. I will be going yellow on the tubes visible in the cockpit as for the rest of the frame I guess it doesn't matter whether it be green or black or white as none will be visible. also here's the technical specs of Pavalos cub Wing span: 2680 mm. (105,5 inch Length 1780 mm. (70 inch Wing area: 100 dmq. (10.76 sq. ft.) Weight: 6/7 kg. (13/16 lbs.) Power: 20/27 cc. (1.20/1.60 cu. in.) four stroke Wing-load of only 67g./ sq.dm. Edited By Brent on 08/09/2014 13:44:46 Quote Link to comment Share on other sites More sharing options...
Brent Posted September 8, 2014 Author Share Posted September 8, 2014 Here's 2 pics I found of the super cub with spats and I think it makes it look a little different from other cubs. which gives it a little more character. what do you guys think? should I do the super cub or the typical j3, you don't see as many super cubs as you do the j3 Quote Link to comment Share on other sites More sharing options...
Erfolg Posted September 8, 2014 Share Posted September 8, 2014 Hmmm, although I mentioned shrinkage due to welding, it was very much it does happen, and can matter in full size engineering. Although where it matters, an allowance for shrinkage is made to ensure that machining operations will produce an item that is accurate enough for its purpose. In your case, it is a simple frame.How accurate does it need to be? I would guess if working from small 3 view type drawings, you will be hard pressed to even produce an accurate drawing. In all probability there will be question marks over the accuracy of the drawing you work from, where the source drawing will contain some errors almost certainly, then the printing processes and finally you scaling up by say. by 72 (1/72 drg). It is probable that not all manufactured frames are the same, due to mods, perhaps slight manufacturing errors. In my opinion, what ever you draw will be OK, without any need to beat yourself up over absolute accuracy and fabrication movements, not mattering a jot. As to the idea of grinding and polishing the joint. To me it does not sound a good idea. A good welded or brazed joint will have a good profile. I know that some industries do polish welds, though this is for purposes of cleaning, such as in the Pharmaceutical and food processing industries. Other industries leave the weld etc as produced even when radio graphing. My principal objection is the work and then, if it is a good joint, it will look good without work. I am sure that there will be others on this site who had the same message drummed into them, when being trained by their lecturers, that message was, "it is all about processing history and then the processing industry!" In the case of steel tubes, much of the properties comes from the manufacturing processes, principally the drawing component. Again I am sure that others will remember the idea, of refining the grain structure and size by drawing. Heating the tube up, will undo locally much of this work. For engineers, the HAZ, is very real, with real world implications, which are accommodated by material sizes relative to duty. For a static model, it would not matter a jot, for a flying model, you are making life hard by that route. Although many are impressed by much of what model engineers do, I just remind myself, that every month, year in year out, when I was 15, AEI (Metro-Vicks), took in about 20 youths, into the training school. These unfortunates would within months be working to an accuracy of greater than 0.005" using a file, steel rule, a futher month down the road, they would all use a file and micrometer working to an accuracy of less than 0.002". The same general processes would continue on lathes, milling machines. In short, I do believe anybody is capable of great things with training, perseverance and methodical working. At this point, the words of my farther come to mind "the difference between a tradesman, and the others is that they can work to time, as you will be doing piecework". It was at this point I decided it was an office job for me. Although if you find metal working fun, that is great and wish you the best. What impresses me about this type of model, is the willingness to spend thousands of hours on their love and joy. I just think, where is that slab of balsa, and if it looks something like, when i squint, well, the job is a good one. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 8, 2014 Share Posted September 8, 2014 That's another variant, the J5 Cub Cruiser. The most obvious differences between the J3/J5 and the Supercub are the latter has flaps, a much more powerful fully cowled engine and metal covers over the suspension bungees. Quote Link to comment Share on other sites More sharing options...
Brent Posted September 8, 2014 Author Share Posted September 8, 2014 Erfolg the 3 view of the fus that I have is from piper them selves at 1/10th scale both frame work pattern for the jig for the sides top and bottom and cross members, however I do not have the wing drawing from piper but I do know the bob nelitz 1/3 scale cubs wing was designed from that drawing yet again from piper aircraft so if I can get a pdf image of his wing plan I can resize to 1/4th to provide the scale wing my cub. I would need to make adjustments to pavalos wing struts and the way they mount to the fus by a few adaptions but really its only replacing what he changed. on his 1/3rd scale cub designed after the 1/4 he went and did the original cub designed wing and fus so he must have found it was easier and possibly less messing around and to go back and redesign the 1/4 scale cub and then build it to ensure it works and then have to remake all the cutting files he probably thought it was best left as is. Here is his magazine review of his 1/3rd scale... now this is mega and if ican produce something half as nice in 20 years from now i'l be proud. **LINK** Please note you require adobe reader for the link to open, I think il go with an aluminum control panel also . I wish I had more room I would love to build his 1/3rd cub from plans. But anyone who loves cubs must check that link out I promises you will not be disappointed Quote Link to comment Share on other sites More sharing options...
Brent Posted October 5, 2014 Author Share Posted October 5, 2014 Just a quick update, Will be starting the build soon . Plans are now printed out thanks to a member on here ( cheers Kevin the plans are fantastic quality.) Now to take them to my friend to inspect and then shoping begins on Stainless steel tubing required. will put link to build when I start it. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted October 5, 2014 Share Posted October 5, 2014 Should be a very interesting project - looking forward to watching its progress... Quote Link to comment Share on other sites More sharing options...
Brent Posted October 5, 2014 Author Share Posted October 5, 2014 Also very tempted to go with the L4 design military scheme because the exta glazing wont affect the fuselage strength as on most models Quote Link to comment Share on other sites More sharing options...
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