I enjoy taking the time to try and visualize how fictional aircraft might actually work in reality. Unfortunately there are some that seem highly impractical from an engineering student's point of view.
One in particular is the Bella Ciela from "The Place Promised in Our Early Days." It features a set of blade-like wings that protrude out front and deploy into contra-rotating propellers, sustaining flight after its jet-assisted takeoff. The blades spin much slower than a conventional propeller as well.
I can get by the closed-loop wing. The V-tail has no issues as far as I can see. My main concern is the large rotating blades that extend far beyond the wingspan of the plane. Taking the Bella Ciela's design out of the equation and focusing on concepts alone..
- How feasible is it to use a propeller larger than the wingspan? Is there any law of physics that prevent this configuration?
- What immediate consequences would be seen in the airflow behind such a large propeller? Would the wings aft of the flow still be able to produce stable lift?
- The blades remain flat when stowed and act as an additional lifting surface; but I assume one could position them so that their loss of lift doesn't affect the balance of the plane (like in the sketch, with them centered)?
- Without twist, can a propeller still provide efficient thrust? Could you reproduce the twist's effect by instead varying the length of the blade's chord from root to tip?
- Are there standard equations for calculating thrust and drag of a propeller that does not have twist? Or of a propeller in general?
I can already see how drag would be a huge issue with spinning something so big. Is there a limit to how long propeller blades can get?
My apologies if I am asking [too many] questions that do not fit this board's criteria. This is just a concept that has had me Googling around for the past few hours. It's neat, and I hate dismissing things as just art without at least trying to justify them.