67
AeroVee 2.1
Rev Z. 01/14/2015
Sonex Aircraft
LLC
© 2014 All Rights Reserved
(Width of Tunnel)
3-1/2"
6-3/4"
Exhaust Cut-out
1"
30
O
Exhaust Outlet Lip
This is a view of the exhaust cut-out before the lips are added.
APPENDIX A - SONEX COWL OPENINGS
Exhaust Cut-outs
The size of the exhaust outlet(s) is a critical for proper cooling.
The Sonex requires 47 to 50 square inches of outlet area for
the cooling air.
The cowling provided with your kit is one of two types: a VW
cowl with premolded exhaust tunnels (detailed below), or a
Universal cowl, detailed on the next page.
VW Cowl with Pre-molded Exhaust Tunnel
The VW cowl with pre-molded exhaust tunnels was phased
out in favor of the Universal cowl in 2004. The change was
made to eliminate the cheeks on the side of the cowl.
The VW cowl must have the exhaust outlets cut open to the
proper size and have air deflector lips added, as shown in the
accompanying photos. In addition, .025" aluminum sheet is
riveted to the exhaust tunnel to protect the fiberglass from the
hot exhaust gasses.
This view of a completed cowl clearly shows the air deflector
lips which are added to the front of the exhaust cut-out. These
lips create a low pressure area which draws the cooling air
through the cowl. These lips are particularly important when
the airplane is in a climb attitude. This aircraft is fitted with
the old-style 4-piece exhaust.
The exhaust lips can be molded from fiberglass, as shown here,
or made from .025" aluminum and riveted in place.
Aluminum-lined
Exhaust Tunnel
This tunnel has been lined with .025" 6061-T6 aluminum to
protect the fiberglass from the heat of the exhaust. The alumi
-
num wraps around the inside as well, but only extends a few
inches back. The aluminum lining is needed only for aircraft
fitted with the 4-piece Sonex exhaust, which was phased-out in
2005.
