Danny Fenton Posted March 16, 2014 Author Share Posted March 16, 2014 Oh no Steve, that will never do.. Quote Link to comment Share on other sites More sharing options...
Tony K Posted March 16, 2014 Share Posted March 16, 2014 Nice work. Do you think you will acheive the weight expectation? You hoped for a maximum of 15 lbs back in December 2010, are you on target? Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 16, 2014 Author Share Posted March 16, 2014 Hi Tony and thank you Interesting question I must confess the model has gotten a lot bigger than the 74" span would suggest. I will try and weigh all the major assemblies so far, should be good for a laugh Cheers Danny Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 16, 2014 Author Share Posted March 16, 2014 Hi Tony, well I assembled the model on the scales. This includes the complete airframe, including tail feathers etc, also all the servos, esc's, rx, retracts, motors, wiring, lighting. 3310g or 7.3lbs So we need to add to that some wheels and legs, some petg glazing, glass cloth and resin, and paint. So I reckon we are on for 10lb if I am careful..... with a span of 74" and a Chord of nearly 12" that gives us something like 888 sq ins, so if we say 3310g then we have a wing loading of around 60g/sq.dm or in old money 19.8 oz/sq.ft Not sure if that's good or not, hope so Wheres BEB and Hooperman when I need them Cheers Danny Quote Link to comment Share on other sites More sharing options...
Tony K Posted March 17, 2014 Share Posted March 17, 2014 Mr. Hooper's "rules of thumb" suggest 16 oz/sq.ft as a reasonable target. Your Apache is tending towards the corpulent at 23% more. Something to watch perhaps? Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 17, 2014 Author Share Posted March 17, 2014 Hi Tony, Not sure about such things. I did find a website that allowed you to button in the figures and it would work it out. Hence coming out at 19oz/sq.ft and thats IF I squander the remaining 2.7lbs on finishing and paint and hit 10lbs The site suggested 10oz/sq.ft for gliders, 15 for trainers, 20 for sports models and 25 for fighters Just not sure how realistic those numbers are.... Cheers Danny Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted March 17, 2014 Share Posted March 17, 2014 Danny I think 20 oz/sq ft is quite light for a model of this size. My (smaller) 1.6m Do27 weighs in at 25 oz/ sq ft and flies very nicely indeed. Quote Link to comment Share on other sites More sharing options...
Tony K Posted March 17, 2014 Share Posted March 17, 2014 Danny, just looking at your figures. Please correct me if I am miscalculating but if your wing area (74" x 12" is about 6,1 sq.ft. Then 10 lbs divided by 6,1 is roughly 1,6 lbs/sq.ft or 25 oz/sq.ft. Edited By Tony K on 17/03/2014 12:15:51 Quote Link to comment Share on other sites More sharing options...
Tony K Posted March 17, 2014 Share Posted March 17, 2014 Why do I keep getting a smiley instead of closed bracket? Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 17, 2014 Author Share Posted March 17, 2014 : followed ) will give a special character... add spaces and you will be okay Tony I owe you an appology, I used the current weight in my calcs not projected 10lbs so yes 27 is pretty high according to this site, but is this reality? 10lb for a 74" model doesn't sound to bad. I have a YT Hurricane that weighs 14lbs and less wing area though I wouldn't want to go that heavy, it does come in a bit hot Cheers Danny Quote Link to comment Share on other sites More sharing options...
Tony K Posted March 18, 2014 Share Posted March 18, 2014 ... and I apologise for interrupting your build thread I did a search of the site and found the following information from BEB. Quote, "But there is indeed a figure which is more related to performance - the "cubic wing loading" - this divides the weight (oz) by the (wing area - sq ft) ^1.5 This tends to give values that relate better to what you might expect the plane to fly like. Floaters being at the 6-7 end, scale jobs 12-ish and fast racers coming in at 15 or so. These figures apply pretty well independent of size - or at least to some degree. BEB" On my calculator 6,1 ^ 1,5 is 15 and 160 divided by 15 is 10,6. By that reckoning there should be no problem. Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 18, 2014 Author Share Posted March 18, 2014 Phew.... I am glad you did post Tony, wing loading is not something I normally look at but I should, trouble is I try to build fairly light, and the weight is what it is, no calculations are going to change that But forewarned is forearmed. The wing is effectively a metal skinned Piper Cub wing, and I would expect it to be fairly sedate, but having said that, this is my first R/C twin! If you hadn't piped up my carelessness would have gone unchecked. So please keep interrupting Spent all last evening messing around with U/C legs. I would like to make some oleos as all the commercial ones are too long, this beasty has little short legs! Anyway for expediency (they can be changed later) I may just bend up some piano wire jobbies. Trouble is I don't really have the lengths sorted. Even the wheel/tyre size is up for debate. The tyres are 6.00:6 for the nose and 7.00:6 for the mains. These numbers seem to indicate that the wheel hubs are 6" nose, and 7" for the mains. Tyre width is the latter figure and is 6" No diameter is specified in the service manual. Ton has the mains as 3" My 3 views scales them to 3.25" I think I will go 3" on the mains and 2.75" on the nose. Its easy to change at a later date. Right better make some drawings and get the wire bender out Cheers Danny Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 18, 2014 Author Share Posted March 18, 2014 Had a little play during lunch, I have used a much thinner piano wire than the Eflites came fitted with. The intention is to have some oleos if the model performs well. So not to much effort in these, however they were a pain to bend, and I am dreading trying to do another one the same Anyway, I need to ask some advice. The piano wire is much smaller than the hole in the U/C blocks. I was thinking of soft soldering two brass tubes to the leg, to pack it out. I don't want to silver solder as the extra heat will take the strength out of the piano wire. It is after all only packing so soft solder good enough? Cheers Danny Quote Link to comment Share on other sites More sharing options...
cymaz Posted March 18, 2014 Share Posted March 18, 2014 Make a brass bushing ?? you could jb weld it in and then put a locking pin straight through Quote Link to comment Share on other sites More sharing options...
Martyn K Posted March 18, 2014 Share Posted March 18, 2014 Hi Danny That is basically what I have done on the Magic. 8g is just over 4mm thick, the undercarriage retract was sized for 5mm legs so I simply sleeved it (the leg) with brass tube and swaged the end slightly. I didn't even need to solder it. It isn't going to move, the retract will die first. The tube was a very tight fit though - it needed hammering into place over the leg. Martyn Edited By Martyn K on 18/03/2014 13:53:28 Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 18, 2014 Author Share Posted March 18, 2014 Mmmm thanks guys, not sure I will be able to drill the piano wire cymaz, and the tube slides over fairly easily Martyn. I might try soft soldering. Cheers Danny Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 18, 2014 Author Share Posted March 18, 2014 It was a little difficult to know how far inside the solder flowed, but I think it went a good way in. I attacked it from either end anyway just to be sure. Fits nicely now Cheers Danny Quote Link to comment Share on other sites More sharing options...
cymaz Posted March 18, 2014 Share Posted March 18, 2014 OH....why can't I be that neat Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 18, 2014 Author Share Posted March 18, 2014 It didn't look so neat before I cleaned it up Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 18, 2014 Author Share Posted March 18, 2014 Well after 3 years and 3 months the Apache is able to stand on its own. This is quite a milestone Had to do the old rough assembly shot didn't I Really looks the part I think, and Hank has made himself right at home. Last seen reading "Assymetric flight for Dummies" I hope he was paying attention....... Excuse the mess..... Cheers Danny Quote Link to comment Share on other sites More sharing options...
cymaz Posted March 18, 2014 Share Posted March 18, 2014 Danny, just an observation but if the nose leg starts to keel over on landing you might find it goes off line and bends badly. I know this, I had a single strut nose wheel leg on my Seagull dual ace. It was a nightmare. However, I bought one of these double leg struts. They are very strong and superb. If you get trouble then there is a solution. Fults leg strut Oh forgot you have a retract nose wheel, sorry. Might still fit though. Edited By cymaz on 18/03/2014 18:43:37 Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 18, 2014 Author Share Posted March 18, 2014 Hi Cymaz worth remembering. If this flies okay, then I will sort some oleos for it but thanks all the same CheersDanny Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted March 18, 2014 Share Posted March 18, 2014 looking GOOOOOOOOOOOOOOOOOOOOOOOD bet your chuffed. Quote Link to comment Share on other sites More sharing options...
Ton van Munsteren Posted March 18, 2014 Share Posted March 18, 2014 Wooooo Danny what a beauty it is , that really put on my fase With every new pic Iam having more regrets that I havent started the Apache as well. Ton Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted March 18, 2014 Share Posted March 18, 2014 Posted by cymaz on 18/03/2014 14:51:37: OH....why can't I be that neat Because you're not Danny Fenton......... Looking good, Danny. tim Quote Link to comment Share on other sites More sharing options...
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