Message text written by Tim Ward
>After buying a Rotax 912S, I noticed the Air Shroud Hood doesn't come as
standard equipment. I am building a Classic monowheel with the classic
cowlings and a fellow builder who is doing the same except with a XS
installation kit, showed me his Air Shroud hood he obtained. What I want
to know is will I need one? If so what is it made of, especially the
resin type? Does it fit with the Classic cowlings?<
My 912S came with an air shroud. It is made of grp (probably using
polyester resin). I made an aperture in the front of the stbd lower cowl
just below and to the stbd of the spinner. I then made a short (about 40mm)
piece of grp tube which was Reduxed(with flox) to the aperture. The shroud
inlet was shortened and a piece of air ducting hose connected the two (the
ducting was pushed inside the shroud). The biggest problem was the shroud
inlet obstructed the connection of the fuel pipes to the mechanical fuel
pump. To overcome this I cut away just enough of the shroud and added a
concave layup to make room for the pipes (don,t forget to allow for the
firesleeve). This slightly reduces the internal diameter of the shroud but
it works OK because the cylinder wall temperature (CWT) stayed within
limits. Don't forget that measurement of CWT is recommended in the
installation manual. I seem to remember that Europa don't bother with the
ducting. They just line up the inlet flange so that it is close to the
shroud so that most of the inlet air goes inside the shroud. Take your
pick.
Regards
Nigel Charles
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