Solving the Aspect Ratio for a canard UAV

[sligo565]

Hi Fellas,

Please find attached a conceptual design of the UAV I am currently designing. I may feel like a dunce asking this but how do i find out the Aspect ratio of my UAV?

Is it merely:

b^2/S of my wing + b^2/S of my fore wing

OR

(b of wing + b of fore wing)^2/(S of wing + S of fore wing)

Or is it something else?!!

[mraero]

Hi sligo565,

The Aspect ratio is defined for each surface versus the aircraft as a whole. So, in your case you will have an aspect ratio of the wing and an aspect ratio of the foreplane. For either surface the aspect ratio is calculated as b^2/S where b is the span of that surface and S is the area of that surface.

Hope that helps. Best of luck with your design!

Rich

[sligo565]

Apologies for not understanding, but does this mean that i add these together to get my whole Aspect ratio or do i leave them apart?

Reason for asking is that i want to find my CL CD etc of the aircraft

[mraero]

You will leave them apart. You will calculate the lift and drag contributions of both surfaces, then add the contributions together to understand the whole. Is that more clear?

[sligo565]

Is indeed thank you!

[macboffin]

Are you not aware that one large prop is much more efficient than a bunch of small ones? Let alone considerations of wiring lengths/weights and current losses!