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I have built this plane: enter image description here

But the nose cone is too light. I have tried adding different objects in the front but each thing was either too light or too heavy. How can I calculate the weight needed in the front?

Wingspan: 30cm (front wings)

Wingspan: 18cm (back wings)

Length of plane: 30 cm

Weight of plane: 12 grams

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2 Answers 2

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This aircraft is "close coupled" meaning the tail is very close to the wing. Lengthening the fuselage will make it easier to balance. This can be done both fore and aft of the main wing. Then add weight to the nose as needed.

Secondly, the tail can be flat. Let the wing do the lifting. Airflow interactions between a fore and aft wing can affect stability.

Finally, have the tail pitched down a bit to help raise the wing angle of attack in flight. You can do this with "elevators" or with the whole tail. The leading edge of the tail should be lower than its trailing edge, providing some "down force" in flight.

A little experimentation may be needed to get it right. Use balsa wood to save weight.

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  • $\begingroup$ this answer is very helpful. However, I made a triangle truss out of cardboard to save weight and it is very rigid. I think that balsa wood would work as well. $\endgroup$ Jan 23, 2023 at 10:45
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For starters put the CG at about 25% of the wing chord line. If you don't want to bother with the math, just balance it on your fingertips. Then slowly work the CG further aft to suit your taste. Further aft = more responsive elevator and rudder, but less inherent pitch stability and less directional or "weathervane" stability.

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  • $\begingroup$ I am new here, could you tell me what CG stands for? Is it central gravity? $\endgroup$ Jan 22, 2023 at 18:39
  • $\begingroup$ @TheRocketfan CG stands for center of gravity - where the balances and where it will rotate around $\endgroup$ Jan 22, 2023 at 22:10
  • $\begingroup$ @ThatCoolCoder. Thanks for the Info. $\endgroup$ Jan 23, 2023 at 5:26

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