**** In a message dated 1/25/2005 1:07:30 PM Central Standard Time, [EMAIL PROTECTED] writes: Dave. . .there is no need to slit the Mylars to get a smooth tip. Go to page 24 of File 3 of the Genie pages http://genie.rchomepage.com/ to see how the Icing putty can be used to form a tip that looks integral to the rest of the bagged wing. ****
Harley, Thanks. As always a very useful and elegant solution. These wings are not for routine use but are simply for flight evaluation for polars. Consequently, popping them out of the bag with minimum work-up afterwards is handy. They're unpainted - one of a kind each. They are each used maybe a dozen times or so and then hung on the wall. Probably about 10 in all if things go according to plan. The project has evolved from some ideas floating around from back in Blaine Beron-Rowdon's time. The recent development of flight data recorders is the enabling technology. Using an Eagle Tree Systems recorder, we've been flying an NACA0009 airfoil on a 2M. Recording airspeed, altitude and time base allows derivation of velocity and sink rate - the essential data for a polar. Setting up the flight profile for about 30 to 60 sec of straight flight from a 400ft or so launch gets a good evaluation of the selected condition. Working through about 8 elevator trim settings gets a reasonable outline of the polar. The NACA0009 really stinks as a thermal airfoil. The abrupt stall in the polars is real. At low speeds it just quits flying. However, it's a great baseline case. A number of 'techniques' have been learned as well as the pros and cons of the recorder. Graduating to the 'Seagull' telemetry system from Eagle Tree will be a big help. They are also working on a modified unit that will be more specifically tuned to sailplanes. That's still being prototyped. Those tests should start in about a month (after Phoenix). The data from the NACA0009 suggests that the current polar model I'm using is optimistic for parasitic drag. However, I had thought that the estimates in my model were conservative - guess not. The kids I've been working with already have the Science Fair part of the project done so I'm now free to take this wherever I want - and I want more airfoil sections of good quality but with a minimum amount of work. Thus the emphasis on a 'quick and dirty' construction technique. If a preferred planform/aiirfoil comes from this, I'll make it pretty. Doubt it could ever be as pretty as the Genie work but I've found that after I fly something for a few months it gets mighty uglified anyway. Reports will be in my RCSD column in a few months. The Eagle Tree folks have been super in helping out with questions. The FDR is a very impressive unit - probably got about 50 flights on it so far and the information it provides is very interesting. Gotta squeeze one into a DLG someday. Thanks, - Dave R RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
