Fredrum
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Everything posted by Fredrum
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After considering aerodynamics, moment arms and other scientific stuff too complicated to mention, the chords of the tailplane and elevator were determined by the size of the fin and rudder and the span was a bit smaller than an A4 sheet. All framed up. This is probably the only bit of metalwork on the model. I had originally planned to drill the holes for the wire elevator joiner, separate the elevators then glue in the joiner. It then occurred to me that I could just embed the wire and keep the leading edge intact thereby keeping everything aligned as built. I’m sure I’m not the first one to do this. All sanded, elevator tapered, leading edges of both parts shaped and the elevator trailing edges separated.
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Harry (third from left) fails his 'A' test for the 3rd time, but gets his revenge on landing.
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Not everyone was displeased when Bob bit the dust after flying too low.
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Very interesting Steve. It's good to see people experimenting. Well done.
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I see that one of the mods has changed the description of this thread. I was wondering how long I would get away with it. I’ll try to behave myself in the future. As a matter of fact, down our way, the new one is almost as good Here's a fin and rudder. Am I forgiven?
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wing rib help wanted
Fredrum replied to thunderstreak.keith's topic in Gliders and Gliding - General Discussion
I'd be happy to Keith so long as you don't mind sending it to Australia (may not end up any cheaper). You probably know what you're doing, but just in case, I do it pretty much the same as Ernie above. I found that balsa doesn't drill particularly well so I drill the holes in the templates, place a template on the balsa and drill through the template holes into the balsa sheet using a suitable sized brass tube sharpened on the inside with a Dremel then cut around the template leaving about 5mm or so all round. Bolt all the (very) rough blanks together and plane & sand down to the templates. I square across the spar cutouts and cut just short of the lines with a razor saw, clean out the bottoms with a narrow chisel (I have a ground-down cheapie) leaving some waste and fine fit the spars, which have already been cut, with a flat or triangular needle file. You can see the results here and here. It occurs to me that if you are making a tapered wing, you would have to make a set for each wing separately in order to have two identical sets of ribs. I hope I'm not teaching your grandmother to suck eggs. Cheers. -
That's a fascinating model Steve. Did you do a build thread for it? It would make a great free plan (any lurking editors listening?).
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How does it go over open structures Steve? That's a very interesting model BTW, what is it? I don't see any elevators. Is that a variable incidence wing? How does it fly?
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Posted by Dave Brooks on 18/03/2016 20:08:50: Looks like a neat job. Will be following with interest to see how it turns out. I have had some success with similar home brewed parkfly designs based on the 'looks about right' principle so no reason why it won't work out. If you really want to keep away from commercially produced covering it is possible to manage using brown packing paper adhered using thinned pva glue. It will also shrink slightly under a coat of thinned pva and can be superficially waterproofed using tape. This method has worked out well for covering foam cores but must admit I've not yet tried it on balsa frames. Yours look rather good and would doubtlessly end up with a better finish from a proper covering job so I suspect the previous recommendations are better. The primary advantages to the 'post office' method is that you can do a lot of wings for two quid's worth of brown paper and tape and can get hold of the materials at the nearest pound shop. Good luck with the rest of the build! Hi Dave. For some reason, I've only just seen your post. Thanks for the advice. The HK covering looks good, but if I get to the covering stage and I still don't want to buy some stuff, might build up a dummy structure and have a go at your post office method. In fact, it's probably worth having a go at it anyway. Cheers Edited By Fredrum on 19/03/2016 12:42:29
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wing rib help wanted
Fredrum replied to thunderstreak.keith's topic in Gliders and Gliding - General Discussion
Hi Keith. How are you doing the sandwich method? I've had great success with it. Super fast and super accurate. -
Thanks Steve. I have an OD parasol wing, open cockpit job that I've had on the drawing board for over a year and the fuselage looks uncannily like Peter Miller's Ballerina. As they say, there is nothing new under the sun. Had some 'me' time today so: One fuselage side frame... ...two fuselage side frames. Outlines sanded to shape. Nose sections filled with 3mm sheet & added some bracing under the tailplane. Just makin’ it up as I go along. Glued one side frame down onto some 1mm sheet the cut around the edges and added hardwood veneer doublers for the wing hold-down dowel gussets. Apart from the 1mm skin and the 3mm infill, everything so far is from 5mm sq sticks. The thick bits are two sticks glued together and the bracing is one stick stripped in half. No more for tonight; ran out of glue Edited By Fredrum on 19/03/2016 12:26:30 Edited By Fredrum on 19/03/2016 12:27:04
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The Marabu looks good Ken. Do you know what kind of temperatures you used on the film in relation to, say, Monokote?
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Thanks guys, although the word ‘designing’ is a bit strong. I drew up a plan with only the minimum of information needed i.e. simple lines for the wing structure and fuselage outline and internal structure. I settled on a 33” wingspan because it fits on two A3 sheets joined end to end and relied on the ‘that looks about right’ school of engineering. I agonized for ages on the clever name I’m hoping for an AUW of around 500g. Many times you read about model designers saying ‘if it looks right, it will fly right’… works for me. Incidentally, I find shrink film quite expensive. In keeping with the ‘fast & cheap’ ethos of this build, any advice on alternative coverings would be most welcome.
