Steve Hargreaves - Moderator Posted May 13, 2007 Share Posted May 13, 2007 Just after some members views on an ARTF Pitts Special I currently have on the bench. I would expect the wing strut mountings between the wings to be exactly in line so the strut can work in tension between the wings. On my model, if you place the wings over each other with the centres aligned I find that the upper & lower strut mountings are about 1/2" out ie the lower mountings are closer together (horizontally across the wing) than the upper ones so when the wings are in place the struts, instead of being vertical are canted out at about 10 degrees....this obviously means you can't tighten the screws up fully or the wood would split.I've spoken to the importers about it & they have checked the stock & say they are all the same & that the prototype was built by a BMFA Chief Examiner who didn't think this would be a problem.....personally I think it is....It seems strange because everything else on the model is beautifully made & fits very accurately including the struts if they were allowed to sit at 90 degrees to the wing.Any thoughts??? Quote Link to comment Share on other sites More sharing options...
Tony Jones Posted July 23, 2007 Share Posted July 23, 2007 SteveAFAIK that's a scale feature. I don't know how the struts are fixed to the wind on your model but wouldn't slightly angled brackets do the job?Best wishesTony Jones. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted July 24, 2007 Author Share Posted July 24, 2007 Hi Tony......yes it probably would...or spacers or anything like that. Following on from my post I had a discussion with Pete @ Planenutz who checked with the factory & they confirmed that the struts should be angled in this way. After a bit more thinking it occurred to me that the reason is probably to allow for some variation in the build of individual planes. If the struts were designed to be vertical & the distance between the wings was a little larger than planned then the (pre-made) struts would not fit without bending the wings....as the struts are offset any variation in distance between the wings can be accomodated by the struts simply being more (or less) vertical.....thats my (new) theory anyway & it keeps me happy!!!!!Incidentally the Pitts has now flown & it flys beautifully....very, very pleased with it despite the fact the undercarriage mounting plate pulled out on the second landing but thats another story concerning the wrong or inadequate glue & materials used in our ARTFs.....I think I've seen your name on one of the threads dealing with this issue so I'll say no more!!! Quote Link to comment Share on other sites More sharing options...
Tony Jones Posted July 24, 2007 Share Posted July 24, 2007 SteveGlad to hear all is OK and she flies well. Photographs I have of the real plane show that it has angled struts. I have a Cermark 1/4 scale Pitts special and the struts are fixed with the best system I've ever encountered: nylon wing mounting bolts with knurled heads captive in the struts. The alloy knurled heads sit in a cut-out and can be turned very easily with your fingertips. The Pitts has a reputation for being tricky, but yours and mine clearly have no real vices. Best wishesTony Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted July 24, 2007 Author Share Posted July 24, 2007 I have lots of pictures of G-IIII which is a Pitts S2B that I went up in for a 30 min aerobatic flight for my 40th!!! The guy even let me fly the thing through a few loops & rolls etc...+5G at the bottom of a loop is pretty entertaining......awesome!!! Not bad for £125...he flies out of Barton near Manchester if you're interested!!!!Sadly all the pictures I have of it are at an angle rather than head on so you can't see if the struts are angled!!! No matter...as long as it flies good & doesn't fall apart it will do for me!!!I've seen the Cermark version, a guy at the club has a blue one with an OS120FS...it looks great & as you say the strut mounting is fantastically effective....my li'l Pitts uses four M3 bolts per strut!!! A bit of a pain but thats Biplanes for ya!!! As you say the Pitts has a reputation for being a bit of a handful.....there was a lot of tutting & sucking air through teeth when I wheeled my little one out...everyone thought it would be a real handful but its just a pussycat (so far!!)....!!! Quote Link to comment Share on other sites More sharing options...
Evan Pimm 2 Posted July 24, 2007 Share Posted July 24, 2007 Actually, when you use the wing flying and landing wires to take the loads, per full size, the struts are always in compression. If you look at lots of full size bipes, there aren't many with struts at 90 deg to the wings, most of them angle the struts. Why? Dunno, but I guess someone out there does.Evan. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted July 24, 2007 Author Share Posted July 24, 2007 No wires on mine....its draggy enough as it is!!!!! Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted July 25, 2007 Share Posted July 25, 2007 If you want to see a really neat and easy way of fixing interplane struts on a full size aircraft and SOOOOO easy to duplicate on a model, go and look at Miller's Tales in the current AMI (August issue) Quote Link to comment Share on other sites More sharing options...
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