Merton Ruck Posted November 7, 2007 Share Posted November 7, 2007 I am in the process of completing a refurb on a D17 stagger wing for a friend,but am at a loss as to where the c.g should be. Anyone out there help please. merton Quote Link to comment Share on other sites More sharing options...
Ernie Posted November 12, 2007 Share Posted November 12, 2007 Hi Merton, Difficult, isn't it..I wouldn't try to calculate it, too much to loose. Why not build a small, but scale balsa glider, and experiment a bit. ernie Quote Link to comment Share on other sites More sharing options...
Evan Pimm Posted November 13, 2007 Share Posted November 13, 2007 The CG will be where it always is-25% MAC. Just jack the model up to flying attitude, measure from the leading edge of the foward wing to the trailing edge of the rear wing and balance the model 1/4 of the distance just measured back from the front wing leading edge. The Beech wings are straight and about the same size so this method will give a safe balance for those first flights. After that well, just 'salt to taste', as they say.Evan. Quote Link to comment Share on other sites More sharing options...
Les Turrall Posted January 2, 2008 Share Posted January 2, 2008 Hi Evan, Will this formula be appropriate to determine the CG of an Ultimate Bi plane with swept back wings, with each wing panel having the same root and tip dimension? Quote Link to comment Share on other sites More sharing options...
Evan Pimm Posted January 2, 2008 Share Posted January 2, 2008 It will, provided you use the chord position 1/2 way out from the centre to the tip. On the wings as described this will be the much maligned MAC, or Mean Aerodynamic Chord. Measure just the same, front of forward wing to rear of aft wing. With the Ultimate, being an aerobatic model you could probably start with the CG at 30% with reasonable safety. Evan. Quote Link to comment Share on other sites More sharing options...
Les Turrall Posted January 3, 2008 Share Posted January 3, 2008 Hi Evan, Many thanks for your prompt reply. Sorry for being so thick, but do I measure the 30% at the position of the MAC or at the fuselage side. Your patience is appreciated!!! Kind Regards Les. Quote Link to comment Share on other sites More sharing options...
Evan Pimm Posted January 3, 2008 Share Posted January 3, 2008 Les, project the 30% at the MAC position to the fuselage. It will probably look like 70% at the top wing centre (or similar). There are no stupid questions, but plenty of silly answers. Intelligence is simply the ability to know the difference.Evan. Quote Link to comment Share on other sites More sharing options...
Les Turrall Posted January 3, 2008 Share Posted January 3, 2008 Evan, Very many thanks for your kind assistance. Your help is greatly appreciated. Les Quote Link to comment Share on other sites More sharing options...
Evan Pimm Posted January 4, 2008 Share Posted January 4, 2008 Pleased to be able to help. Evan. Quote Link to comment Share on other sites More sharing options...
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