I don't understand how the ventilation system is intended to work on the
Europa. That is, I note that most are fitted with NACA inlets on the sides
for fresh air inlet but I haven't seen any standard way for air to exit the
cabin once it gets in. Elsa had two 3" vents added to the baggage bulkhead
but this seems minimal for good cooling in hot weather. It seems as if
efforts are concentrated on getting air into the cabin rather than
considering the complete path. While it is true that increasing the inlet
area will likely increase the pressure and thus the flow, it seems that flow
could also be increased by adding additional outlet area. Is leakage around
the retraction and brake levers into or out of the cabin, i.e. is this the
intended exit point?
Is the location of the NACA inlets critical? Kim Prout's vents didn't satisfy
him initially and he eventually added little extensions which protrude into
the airstream to increase the flow -- this increases drag above that of a
normal NACA vent of course. NACA inlets are supposed to be located at a
relative high pressure point; where is this on the Europa?
Further, once air is passed through the baggage bulkhead where does it go
---From there? I don't see any outlets specified on the plans. My understanding
is that allowing air to escape perpendicular to the airstream through
existing holes e.g. around flap hinges, tailwheel shaft, and servo tab drive
would cause increased drag. Air passing out through the opening between the
fin and rudder probably causes little drag but the openings through the rear
bulkhead are so small that probably only a small fraction finds this path.
Per the recent articles in "Kitplanes" I would guess than a NACA type
extractor vent located on the fuselage top slightly aft of the wing trailing
edge (relatively low pressure here?) might be appropriate. Has anyone tried
this?
Is the seal at the wing fairing sufficient to prevent leakage there via the
spar openings?
What about sealing of the tunnel bulkhead around the flap drive; how is this
done? Is it necessary? Are accordion type seals as used on axel shafts of
front wheel drive cars appropriate?
Any thoughts by those who have trod this path before would be appreciated.
Regards, John
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