I am much in favour of improving the internal efficiency of the cooling
system, but it is perhaps worth reminding folk that the efficiency of
the propeller can also transform cooling. Those of you in the club can
read the report of my change from a low twist prop to a high twist one
in edition 65 of the Europa Flyer, p4 archived on the club website. In
essence most propeller blades seen on Europas (but not on WW2 fighters,
turbo props or Red Bull Racers) have low twist, perhaps 12 degrees
difference in blade pitch between the tip and 1/3 radius. This is not
nearly enough and means that at any speed above idling on the ground the
inner part of the blade is not keeping up with the air flow and is
effectively diverting air away from the cooling air inlets of the
Europa. Any plane optimised for speed has prop twist in the 24 to 26
degree range, and fitting such a prop totally transformed/abolished my
cooling issues with my 914, as well as improving performance to a degree
equivalent to an added 7.5 HP. Happy New Year, David Joyce, GXSDJ
On 2017-12-27 08:06, Roland wrote:
>
> Hi Ruedi,
>
> I've read the thrilling story about vapour lock in the EF. You've certainly
> handled
the emergency as well as possible. Most important you went away from the
scene unhurt despite the very dangerous U-turn after the EFATO. Thanks very
much for sharing this experience at this point.
>
> As for the high oil temperature (120C after take off on maximum power), I
> think
this shouldn't be a general problem (as apposed to vapour lock of course for
obvious reasons), especially in summer. The redline is 130C and I see
oiltemperatures
approaching and sometimes even exceeding 120C in extended climbs on
a regular basis with the 914 Turbo.
>
> Rotax wants the oiltemperature to reach 100C MINIMUM at least once on each
> flight
to boil the moisture out. So my understanding is, that oiltemperatures too
low are much more critical and that was also confirmed by Rotax stuff in a chat
on the AERO in Friedrichshafen. A modern semi synthetic oil should be well
capable to deal with high temperatures - that's what it was also designed for.
Full synthetic oil even more so, which I do not (yet) use for the single reason,
that I sometimes can't avoid 100LL when travelling.
>
> That said in my Europa the CHT's were the critical bit before I finally found
a perfect set up with almost all cooling air forced through the radiator, a
water
thermostat and the (7-row) oil cooler partly blanked in winter.
>
> Regards
> Roland
> PH-ZTI
> XS TG 914
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=476809#476809 [1]
>
Links:
------
[1] http://forums.matronics.com/viewtopic.php?p=476809#476809
[2] http://www.matronics.com/Navigator?Europa-List
[3] http://forums.matronics.com
[4] http://wiki.matronics.com
[5] http://www.matronics.com/contribution
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