Thread: Bi plane wing
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Old 09-11-2020, 09:34 PM
  #3  
bandicootf16
 
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Hi Rune
Why do you think your wing is too big. What flight characteristic arenít you happy with. I guess the function of the wing is to provide lift to oppose the weight of the model. Lift is a function of wing area and airspeed. So in deciding on a wing area I guess the models weight and desired airspeed must be considered. A lighter model and or higher airspeed will mean less wing area is required. It would seem most bips have a wing area of about 90 dm^2. Naruke has been designing bips for many years. The Advantage has a area of 92.8 dm^2. The root is 350cm and tip 150cm with a span of 1760. This is for IC so probably a take off weight of 5500g. I think you have a FH Neo Stage Bip which has a wing area of 92.3 dm^2 and span of 1800 cm. The Futaba Leader G (and A1) has a wing area of 90 dm^2 and span of 1720. The original Leader had a span of 1770 cm. Iím not sure what the original wing area was but the G redesign seems to have an increased root cord from the original. The Nurila Glacial has a span of 1740cm. The area is not quoted but the wing would appear to be similar to the Naruke Advantage. The Akiba Accel has a span of 1740cm and an area of 82.8 dm^2. The root cord is 310cm and tip 125cm. This is certainly the odd one out and it also has a so called dogtooth as per his Fantasista and now Interceptor.

It it would appear that snap performance was a major factor in the Leader G wing design with reduced wing span and very small tip cord. This has been compensated for by increasing the root cord to maintain the wing area. Another consideration in Biplane design is wing efficiency. Increasing the distance detween the top and bottom wing increases efficiency which potentially means a decrease in wing area. The Accel has a very deep fuselage so this might be the reason for the lower wing area at 82.8 dm^2 as opposed to 90. I would guess the design weight of the Accel would be 4750g. Again this allows a smaller wing say as compared to the Naruke Advantage with a flying weight of 5000g plus. Akiba is very fussy when it comes to weight. A model can be too light for itís designed wing and Iíve seen him add weight to a model because it was too light and didnít fly correctly.

The sweep on the Futaba Leader G would appear to be about 20mm, as per the Neo Stage and Advantage. The trailing edge of the Accel is actually sweep forward 10mm at the tip.

I guess you canít go too far wrong in following the Futaba Leader G wing design, a large root cord of say 350 and small tip of 130 to 150 with a span as you suggested. A double tapper might be worth considering or an curved leading edge.



Last edited by bandicootf16; 09-11-2020 at 09:37 PM.