Don and Blaine had interesting points in their recent posts. These got me thinking again.
Don pointed out the increased efficency during circling with higher dihedral and Blaine pointed out that a gyro can make spiral stability a moot point to the pilot of any aircraft. But this question still rings in my head...what is a good compromise for effective dihedral angle (EDA) for a thermal soaring ship? I have to assume that the addition of a gyro can only improve the handling and not the efficiency. Having read (and reread) Blaine's articles on Spiral Stability in Model Aviation published years ago, I seem to remember that he indicated that upwards of a 10 degree EDA was good. For straight wing panels, that means a 20 degree bend in the wing rod. Wow, that's a lot! Mike Garton just wrote an article in his Model Aviation column about this area of aircraft stability. If I'm not mistaken, Mike said that many of the straight wing planes produced recently have about 5 degree EDA. Since most wing rods are bent to a 5 degree bend, that makes the EDA only 2.5 degrees for all those aircraft. I may have mis-read Mike's article, but he may have made a mistake there. The point I'm making here is that many TD planes have very low EDA's. Through my experience, I've settled on a preferred EDA of about 5 degrees as a good compromise for spiral stability and landing performance. This has always produced a sweet handling plane for me. I'm not saying that 5 degrees is ideal for contest work though. As anyone with an Addiction or Compulsion (or many other) aircraft will attest, these low EDA planes land with very high accuracy. Mike Garton mentioned his landing accuracy findings in his article, but I wonder if they can be applied universally. He said that higher EDA didn't affect his landing accuracy. I suggest that low EDA probably does reduce the ability of cross winds to disturb a plane's trajectory. Mike presented his data points on this subject, I'm wondering if other pilots have ventured there? It may be time for me to have Don Richmond make a higher bend angle wing rod for some 'spuriments. Don Stackhouse mentions that he has figured out the mathematics regarding dihedral and turning, I'm hoping he will expound here on his findings. Martin Brungard Tallahassee, FL "Soaring: Where screwing-up is an art" _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
