Re: [RCSE] Initial CG on a scratch ship...

[Harley Michaelis]

Title: Initial CG on a scratch ship...

Brent. . .I would never tow a ship on its first flight. Can't you find a little hill or mound and start with some hand tosses?    Having quite frequently seen inquiries about an initial CG, it might be of value to follow the steps I do with a new ship to avoid calamity. All of mine are scratch built and each is a little different, so it has to be sorted out for each one, step by step.    Just go to the Genie pages at http://genie.rchomepage.com/ and get into File 8. ----- Original Message ----- From: Douglas, Brent To: soaring@airage.com Sent: Thursday, April 20, 2006 10:39 AM Subject: [RCSE] Initial CG on a scratch ship... Just trying to get a rough idea where to start here, what formula you might use to come up with a starting CG . Picture a 200 inch wing, root chord about 11 inches, tip about 5, straight leading edge, tapering TE. Modern airfoil, HQ 2.5, 12 - 10 percent thick.    My thought was to go mid span, take some percentage of the chord there, then mark the root that far back - example:  30% of 8" becomes 2.4 inches - mark the root at 2.4 inches from the leading edge.  2 questions - how far off is that logic, how far off is 30%?      I'm towing this ship for the first flight, so I'd like to be pretty close, erring to the nose heavy side. Thanks! Brent