Design Improvements for the Zenith 601 HDS: Wing Locker Doors
Wing Locker Doors
Air leakage from the wing locker doors onto the top of the wing
has a significant impact on the lift characteristics of the wing.
This may seem surprising, since the gap between door and
wing is small when examined on the ground. But the gap
increases somewhat in flight due to the low pressure on top
of the wing, and the air shooting out of that gap
disturbs the attachment of the airflow to the wing sufficiently
that lift is reduced.
To eliminate the negative impact of the air leakage, we have added
1/8 in. thick, 1/4 wide adhesive foam strips as seals to the locker
doors.
The material is readily available as window stripping material
from any hardware store. This is not the dark, almost black foam that
is hard to compress, but the white foam that is a bit like memory
foam. It can be almost completely compressed
and exerts little pressure once it
has been compressed and held for several seconds. As a result,
the foam exerts little pressure on the wing locker doors, allowing
them to close as tightly as before.
The seals have improved performance to an amazing extent.
For example, at 890 lbs gross weight and 4,800 rpm of the
80hp Rotax 912, cruise speed has increased from 97-98 kts before to
100 kts after installation of the seals.