My question is fairly simple: how does one decide on the ideal dimensions and ratios for a flying wing given the target cruising speed and payload or other relevant flight characteristics.
For a more conventional aircraft, I feel like I have a fairly good intuition as far as choosing the wing design to get the desired characteristics. Wing area is roughly proportional to payload for a given flight speed. An undercambered airfoil will be slower and lift more, but not perform well inverted. A more symmetric airfoil will be faster and more acrobatic. A relatively thin airfoil will be faster, but may have a high stall speed. A higher aspect ratio wing will be more efficient. etc.
Those are not ultimatum, but rather rules of thumb and variables I consider when I am designing a new aircraft.
In the case of flying wings, I feel like I have much less intuition about how my design choices will affect the final aircraft. Specifically, what are the (general) effects of increase sweep, more taper, a larger center section, and higher aspect ratio on flying wing flight characteristics?
The designs of many of the most popular flying wings follow a relatively similar ratio: the versa is pretty similar to the Ritewing Zephyr II is pretty similar to the TBS Caphirana.
Is this some optimal shape? If so, how come the Ritewing Zephyr III and Ritewing Drak, which are entirely different, perform so spectacularly?
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