Valid range of wing efficiency

[Guest]

Oswald efficiency factor range [/p] [/p]The following is a quote from a web search which CLEARLY states the definition of wing efficiency. Why is this an issue?? when FS2002 creates a CFG file (when first loading/running the model) it will often create a value for WING EFFICIENCY which could be 2.00, 6.50, or even 12.50 and is outside the valid range. This could indicate a condition in the AIR file which does not accurately represent the aircraft. Since there is little documentation on the AIR file, these properties will be learned by experimantation. [/p] [/p]14:30 11/14/2002The Oswald efficiency factor [ e ], accounts for thefact that, because aircraft design is a compromise, nowing or airplane is as efficient as is theoreticallypossible. The theoretical maximum value for the Oswald efficiency factor is one.The smaller the value of e the less efficient theaircraft. The Oswald efficiency factor affects theeffective induced power required, i.e., the powerrequired associated with the production of lift.Typical values for light aircraft are from 0.5 to 0.8.Based on flight test results, the Bonanza, with gearand flaps up, i.e., clean, has an Oswald efficiencyfactor of approximately 0.56 to 0.65. Extending thegear and/or flaps has some effect but not a large oneon the value of e.© David F. Rogers, 1996 [/p] [/p] [/p]The valid range of wing effciency is: 0.0 - 1.0 [/p] [/p] [/p]Typical wing efficienciesTwin Engine - Widebody Aircraft - 0.85 Twin Engine - Commuter Aircraft - 0.85 Multi Engine - Widebody Aircraft - 0.84 Twin Engine - Propliner Aircraft - 0.81 Multi Engine - Propliner Aircraft - 0.80 Single Engine - Light Aircraft - 0.80 Military Aircraft - w/ external stores - 0.70 Vintage Bi-plane - w/ struts & bracing wire - 0.70 Generally speaking, efficiencies fall in the range of 0.67 to 0.88 -- from old vintage planes at the low end, to modern jetliners at the high end. With this simple chart, one can gain a general or `ballpark' idea on this parameter. [/p] [/p]Note: content is for general FS development, comments welcome. [/p]Gregory Abbey - Edwinnengineering

[Guest]

Thank you Greg, for an interesting and informative summary.It would appear then that my team's Socata TB20GT's oswald_efficiency_factor=0.860 is well within the 'Valid Range' of values, and is representative of a modern, highly efficient wing and fuselage design.

[Guest]

>Thank you Greg, for an interesting and informative summary. >>It would appear then that my team's Socata TB20GT's >oswald_efficiency_factor=0.860 is well within the 'Valid >Range' of values, and is representative of a modern, highly >efficient wing and fuselage design. [/p] [/p]Socata TB20 [/p] [/p]Hi Bill.. [/p]Yes.. I have flown your Socata TB20 project, but only around the Island of Honolulu. { smile } [/p] [/p]Base on the above table, and the efficiency factor that you quoted, I'd say the Socata TB20 has a state-of-the-art wing design!! Additionally, do I have permission to post the graphic of you in the left seat of the Socata?? { grin } [/p] [/p] [/p]Gregory Abbey - Edwinnengineering

[wsieffert 0]

I don't think fs2002 is making the Oswald efficiency factor greater than one. Some aircraft designers force the Oswald efficiency factor greater than one. If you try and use FS2002Pro Aircraft Editor, it will NOT allow an Oswald efficiency factor greater than one if you touch any of the aerodynamic properties. When you try saving, with a number greater than one, it stops and tells you to decrease the number.

[Guest]

Thanks for posting the table of nominal efficiency ranges. I was just at the point where I am considering this factor for my ultralight a/c. I was able to cheat a bit because my wing is the Clark-Y unmodified except for mimicing the attractive flat (apparently canted) wing tips of the Aviat Husky, which uses a modified Clark-Y airfoil. So I just used the value from the FSEd file for the wonderful model by Steven Grantand Fred Choate.The Husky A-1B OE factor is 0.76534 and assume they took this value from Aviat specs.I set mine to 0.76 the a/c is clean for an UA without many wires, just two wing support struts using an Eppler strut profile for efficiency.I have not seen the OE greater than 1, but I suppose you could edit the config file to force it, but as far as I know, the air file only gets modified from the data in FS Ed, so the range check should catch it.