JEFF ROBERTS wrote:
> We'll it's time for me to put my plane back together after a long annual
> and a few mods. I have been considering going back to using 50/50
> instead of the Evans.
This is funny. I was just about to start a topic about this.
Probably this spring I'm going to start up the engine for the first
time. I'm about to pour in some coolant in preparation of this rewarding
event. But after reading the archives, I still can't decide what coolant
to use.
My Rotax 914 is factory equipped with a 1.2 bar cap. Can this cap be
used for 50/50 and Evans?
What do people advise? My situation is as follows:
I have an intercooled 914, will be using the high twist Woodcomp
(3000W/3) and have extensively modified the cooling properties of the
cowling:
1) I cut away the entire "duct", and have some sort of a scoop under the
cowling with a diffuser and adjustable flap on the exit. The idea here
is to reduce drag, reduce frontal area, and to improve cooling at the
same time because the air-entrance is now lower on the belly, perfectly
in the prop-wash.
2) I used the circular openings in the front for taxi- and landing
lights. For the cylinder cooling I made two nasa-ducts in the top
cowling, with the air aimed between the front and rear cylinders. The
air openings have a slightly smaller surface than the original openings,
but they are situated in a better position, and the air is aimed
directly to the parts that need cooling.
For these reasons I estimate that my Europa has better cooling
properties than the factory Europa. Most flights will be carried out in
economy cruise on higher altitudes. Although the climate in the
Netherlands isn't very warm, I plant to travel a lot and will visit
warmer countries during the summer season.
As far as I understand from the archieves Evans has less risk of boiling
over, but has less cooling capacity. Since my cooling is hopefully
better than standard, I think that boiling over won't be an issue. So,
there is no advantage of using Evans here, is that right? At the same
time there is no need for the improved cooling capacity of 50/50 either.
If it doesn't really matter, I favor 50/50 because it is readily
available, can replace/add it anywhere during travels if need arises,
and it is more economical.
Concerning the cooling of the Rotax: The local glider club uses a Dimona
with a 914 for towing. That thing has never had any cooling issues,
while it sometimes has to wait very long (student glider pilot is being
teached, or a lot of traffic on the adjacent runway), operates on hot
days, and is performing long full power climbs exclusively. The whole
cooling problem with the Europa appears to be cowling-related. That's
why I modified the cowling, hoping to get the same cooling performance
as the club Dimona. ;-)
--
Frans Veldman
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