Hi Mike,
Our cooling problem was temps reaching 450 deg F in the lower engine
cowl, near the exhaust. The heat melted tie wraps into drops of nylon,
took the temper out of the springs holding the exhaust on, and caused
damage to the cowl itself. We first found that the gills were allowing
air to escape without cooling much of anything. After closing them off,
we found that the cooling air was coming in the upper inlets, crossing
across the top of the engine and then going down the back of the engine,
between the foot wells, bypassing the cylinders and the exhaust area.
Closing off the area behind the engine, between the foot wells, forced
the air to act like it does in a conventional air cooled installation.
It forced the air to pass around the cylinders, top to bottom, and then
to pass around the exhaust, before exiting the lower, rear, of the cowl.
After the two changes mentioned above, the max in-cowl temps dropped to
250 deg F, and our oil temp in the climb dropped 20 deg F, from 240 deg
F to 220 deg F (100 deg F ambient at 12,000+ feet density altitude).
The key to our changes was to treat the engine as you would an air
cooled aircraft engine (the Rotax cylinders are, after all, air cooled).
Bring air into the top of the cowl, force it down around the cylinders
with ducting/baffles, past the exhaust, to finally exit the lower rear
of the cowl.
After making these changes we carefully monitored the temps at the top
of the cowl, near the ignition and carbs, to make sure we had not
negatively affected their cooling. Those temps remained barely above
ambient, only a few degrees different than before.
Regards,
Terry
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Mike Parkin
Sent: Wednesday, April 01, 2009 11:22 AM
Subject: RE: Europa-List: 914 Waste gate servo mounting position
question
Terry,
While I acknowledge your comments and development. My comments where
based on my experience with a monowheel AND on Andy Draper's comments
on the original Europa development with G-YURO. Plainly there are
variable issues with individual aircraft. I have the Graham Singleton
firewall fitted to my aircraft and have never had any problems apart
---From the Evans stuff seeming to push the cooling system past its
capability. However, what exactly do you mean by 'closing off the area
between the footwells'. Is this a problem that the Singleton firewall
avoids?
Regards,
Mike
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Terry
Seaver (terrys)
Sent: 01 April 2009 18:46
Subject: RE: Europa-List: 914 Waste gate servo mounting position
question
We spent nearly a year looking into and fixing our cooling problems. We
installed temperature probes throughout the engine compartment and
performed data logging on those temps, as well as engine parameters
(rpm, MP, oil pressure, oil and water temps, CHTs, and fuel flow). Each
parameter was sampled once every 2 seconds during flight and downloaded
to a lap-top after the flight. We found that the gills allowed the
upper cowl inlet air to escape without contributing much to engine
cooling. After closing them off, we found no significant rise in upper
cowl temps, but with a noticeable improvement in lower cowl temps.
Closing off the area between the foot wells was the final fix that made
the temps come down, from a max of 450 deg F inside the cowl to a max of
250 deg F.
Regards,
Terry Seaver
A135 / N135TD
XS monowheel with 912S
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Mike Parkin
Sent: Wednesday, April 01, 2009 9:31 AM
Subject: RE: Europa-List: 914 Waste gate servo mounting position
question
I do not have the "gills" open (left them closed since it has been
established that they were a development item providing little cooling
benefit on shut down(positioned too low) and are now a "leftover" item.)
Regards
Bob Harrison.G-PTAG
Bob,
That statement is just not correct. In flight, there is a noticeable
flow of hot air from the gills - obviously aiding the flow of cooling
air across the cylinders. Perhaps that is why you have had cooling
issues on Jabiru and Rotax.
Regards,
Mike
http://www.matronics.com/Navigator?Europa-List
http://forums.matronics.com
http://www.matronics.com/contribution
http://www.matronics.com/Navigator?Europa-List
http://forums.matronics.com
http://www.matronics.com/contribution
Checked by AVG - www.avg.com
04/01/09 06:06:00
|