The shelter must be fully covered the propeller with no gap.

搭设防护棚一定要做到全覆盖无缝隙！

youdao

After the vortex distribution is solved according to the boundary condition of no-flow-penetrating through the blade surface, the velocity reduced by the propeller can be calculated.

根据桨叶表面流动不穿透条件解出升力面奇点后，然后再求它们对流场的扰动。

youdao

For those who like their historic buildings to come in the shape of stately homes, ancient monuments and places of worship, it's probably no compensation to hear the awesome propeller is housed in a cathedral-like chamber.

BBC: NEWS | UK | Magazine | Concrete steeped in history

It is no different from a pilot hopping into a single-propeller Cessna and attempting to fly to the moon.

FORBES: How Impossible Dreams Can Destroy Value In Mid-Sized Firms