Cyclicscooby Posted March 24, 2012 Share Posted March 24, 2012 So, i've picked up the odd snippit of info here and there, like having to increase the size of the rudder in some cases, but can anyone explain the finer details of this re-scaling process..?? I'm building a 1/8 CH750 STOL from a fullsize plan.. I've increased the whole rudder assembly, a bit..!! (Technical answer) and also added a bit of extra chord to the elev... I've copied the wing 100% tho... Is that gonna be ok.? I presume WHAT scale you choose makes a difference too... Smaller = bigger surfaces I presume.. Tell me all you know... Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
kevin wild Posted March 24, 2012 Share Posted March 24, 2012 Hi I remember reading in RCM&E quite a long while ago that there is a way of working out the size of the horizontal stab in relation to the wing and the distance between them. once the numbers a crunched it gives you a value (Vbar) which is a very good indication of stability. from this a safe c of g can be worked out Google Vbar and you may come accross the formuli. if not I'll see if i can dig the mag out and refresh my memory kev Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted March 25, 2012 Share Posted March 25, 2012 Chrissie It is rather going to depend on what sort of fllying you intend to do. You can certainly build everything to exact scale, it just that as planes get smaller things happen faster and most flyers don't like to have to wait (even for a fraction of a second) for a control surface to have an effect hence the full span strip ailerons that in full size would be reserved for out and out competiton but in model sizes appear on quite humble sports flyers. Scale control surfaces are also likely to require the same attention to CofG positioning as they do in full size. Scale rules - OK! Quote Link to comment Share on other sites More sharing options...
Cyclicscooby Posted March 26, 2012 Author Share Posted March 26, 2012 I did a search for Vbar, but only got Heli stuff pop up.. ?? I will look into it tho.. Thanks Kevin.. So basically, it wont hurt to make them a bit bigger.. As long as they're not smaller, it should fly... ?! Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
kevin wild Posted March 26, 2012 Share Posted March 26, 2012 Hi http://members.multimania.co.uk/A75Church/tips3.htm it's the part on vbar that I was talking about. if you calculate Vbar it will tell you how stable it'll be. for a high winger that you want to be a nice relaxed flyer then the Vbar shouldn't be too low. a couple of aerobatic planes i built years ago had Vbar of about .35 so It'll have to be higher than that kev Quote Link to comment Share on other sites More sharing options...
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