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Roland
Joined: 30 Nov 2009
Posts: 334
Location: EDLE
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 Posted: Mon Aug 08, 2016 11:35 pm Post subject: Re: Fwd: Re: Cooling issues XS 914 on the ground |
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Bud, thanks for your offer. I already tried to attach photos but will try again later. I removed the mentioned sealing again, since it obviously made the situation worse.
Again, in flight the setup worked perfect under all conditions-I even didn't came close to CHT-limits when climbing FL200 in summer without a level off.
CHT reading should also be correct since I once shut down at 118°C and could hear the coolant boiling a little bit.
Regards
Roland
PH-ZTI
XS TG 914
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budyerly(at)msn.com
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| Posted: Wed Aug 10, 2016 9:48 am Post subject: Fwd: Re: Cooling issues XS 914 on the ground |
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OK Roland,
I am confounded by your ground cooling issues. I was checking out an
Instructor pilot for N12AY at 95F and he took a full 20 minutes with a tail
wind doing ground checks then taxied for another 5 then ran up and we did in
fact hit 245F on the ground. On takeoff it stayed at 245 and we leveled at
1000 AGL after takeoff for 2 minutes and temps dropped below 240 then we
climbed to 5000 AGL never hitting 245 again. On a stock setup, you should
see the same.
Some find Drop box works very well for photos rather than albums but photos
are a pain no matter what we do. I love how instant communications burns up
so much of my day.
Regards,
Bud Yerly
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Roland
Joined: 30 Nov 2009
Posts: 334
Location: EDLE
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| Posted: Wed Aug 10, 2016 11:42 am Post subject: Re: Fwd: Re: Cooling issues XS 914 on the ground |
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Bud, that is really amazing. How can it be, that you can make 25 minutes of ground operations at 95F in a tailwind with a standard setup? OTOH my CHT also drops immediately several °C when changing from climb into a cruise setting. But when I landed after a 2 hrs cruise flight last weekend and reached the parking position in a brisk tailwind the CHT rose literally one °C every second.
Overheating with the XS cowling is quite common, even in middle Europe. David Joyce or Frans Veldmann or the Scandinavian Europa owner I met last weekend can tell a story. Because of that issues many many Europa owners made their own - sometimes radical - modifications and because of that Neville Eyre designed a better cowling with a lower air inlet. When I walked along the parked Rotax-powered aircraft at the fly in last weekend, there wasn't even one of them with a cooling duct similar to the Europa.....
Today I sealed a gap of 1 mm between the tunnel and the radiator. I also managed to increase the gap between the tunnel edge and the firewall (which is completely in front of the gear frame). As I said, I removed the sealing between the upper tunnel edge and the cowling again because it increased CHT. Removing the thermostat is still on my to do list.
I'm afraid no pictures at the moment, although the size is within the allowed limits.
Regards
Roland
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Roland
Joined: 30 Nov 2009
Posts: 334
Location: EDLE
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| Posted: Thu Aug 18, 2016 11:37 pm Post subject: Re: Fwd: Re: Cooling issues XS 914 on the ground |
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Hello all,
I succeeded in the improvement of my cooling problems! Yesterday (28°C/82°F, MTOM, light wind around 5kt) I made two flights with climbs to 5500 ft with several minutes at the holding point and after landing also several minutes to cool down the turbo. I didn’t try the limit of 118°C CHT (it boils around 120°C), but at 103°C temperatures only went up very slowly (2200 RPM, climb pitch, something like 1°C every minute). Mind you, my CHT climbs rapidly to 90°C due to my water thermostat. My estimate is, that I match or at least come very close to the figures Bud Yerly quoted for ground operation.
In the climb I didn’t even come close to oil- or CHT-limits. In a steep climb at MCP/80KT/MTOM I only touched 110°C oil (mind you with a 7-row oil cooler!) and 107°C CHT. On the other hand the oiltemperature fell to 75°C in the quick descent from 5500ft, which might be too much in winter, but it’s easier to address a problem of running to cool….
On the second flight I closed up the gills on the upper cowling, which didn’t make a big difference. But since they seem to mitigate heat buildup at low revs and just before/after shut down (where I had the biggest problems) under the cowling a bit, I’ll leave them open.
So how did I achieve the improvement? (Bud, I followed your advice and tried to think like an air molecule 
I let the gap between the top of the cooling tunnel and the cowling open, since closing and sealing it added 5°C to the CHT and also increased the oiltemperatures especially in the climb significantly. My theory: since the front openings in the cowling are rather small, it seems like the gap - in sum - more contributes to cooling of the engine than its closing/sealing adds to the airflow through the radiator. Also the gap is just in front of the oilpump and thus obviously cools the oil several °C. In this regard I didn’t follow Bud’s advice for the mentioned reason but maybe will reinstall the sealing in due time to test with the new setup.
I opened up the gap at the air exit from the lower cowling just in front of the firewall (which is completely in front of the nosegearframe in my aircraft) to about 1 inch.
I cut away the edge at the air exit of the lower cowling completely.
I sealed a gap of 1mm between the top of the tunnel and the radiator. I made also sure, that the complete cooling tunnel is properly sealed.
(I already had) an aluminum sheet at the bottom of the lower cowling to force all air flowing through the tunnel through the radiator, leaving only a gap of ½ Inch below the radiator for the 7-row-oilcooler mounted behind the radiator, 4 rows overlapping with it.
I bended the lower ends of the cooling tunnel in such a way to the inside (I know that this is unconventional), that more air/heat from under the cowling could exit only compromising the heat exit from the coolers a little (if any).
I sealed the joining between the upper and lower cowling, the fuselage in front of the windscreen and the two access holes on the top thoroughly with a Tesa-sealing band (very simple and cheap).
Still on my to do list is the removal of the water thermostat to increase the margin to the CHT-limit significantly.
After all I’ve learned from the countless individual solutions, that there is no such thing as “plug and play” (a Woodcomp SR 3000 aside) to address the cooling issue of the XS cowling. I’m even afraid, that my actions might lead to another result in another Europa (e. g. the Mono). Finally I have to agree with Bud Yerly, that one can improve the given setup to a point, where you can live with it 99,9% of the time. Still, Frans and Ilona did the most sophisticated solution but with huge modifications, that are definitely beyond my own skills.
I’m a lucky man now, thanks to all who contributed to this thread 
Regards
Roland
PH-ZTI
XS TG 914
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