Frans
Just back from holiday in US and seen your list of problems.
Have you seen the Tropical Chin Intake?
I have just fitted one to my 912S installation, still a long way from
flying.
It forms a sharp edged entry to the large rectangular inlet with a much
smaller eliptical entry formed from aluminium.
I think I downloaded it from the Europa Club but Popular Flying Assn
mentioned at the top of page 1.
Frustration is a killer!
Best Wishes
JR Gowing Kit 327 in Oz
----- Original Message -----
From: "JEFF ROBERTS" <Jeff@rmmm.net>
Sent: Sunday, June 06, 2010 3:52 AM
Subject: Re: Europa-List: Cooling issues, once again!
>
> Frans,
> I have the 912 set up so I might not know what I'l talking about but...
> I had the very same issues for the first 150 hours. Every time it got
> hot I was in trouble with temps at their limit. I made the shroud for
> over the cylinders. I lowered the oil radiator 2 inches behind the
> water, I sealed everything, I made new inlets in the upper cowl, and
> still didn't get it solved completely. I then finally lowered the
> metal duct down an inch or so, so the bottom radiator reached the
> lower cowl without the sealant and bam. My temps dropped 30 to 40
> degrees. I believe two things helped in this. The radiators we're
> getting more air but the big thing was by lowering the duct it opened
> the bottom for escaping air. Not sure if this all applies to you but
> if you have the duct up to high close to the muff all you need to do
> is lower it. You'l be needing to ad a flap in colder days to get
> things in the proper temp range.
> By the way the shroud did even the cylinder temps out but it didn't do
> much to cool the water or oil.
>
> Jeff R. N128LJ Gold Rush
>
>
> On Jun 5, 2010, at 5:28 AM, Frans Veldman wrote:
>
>> >
>>
>> Gentlemen,
>>
>> Although my initial cooling issues have been improved upon, I'm not
>> satisfied at all with the cooling of my 914.
>>
>> Now, with increasing ambient temperatures, I have to severely limit my
>> climb outs. Cruising is ok. During climb, both the water temperature
>> and
>> oil temperature approach the red line, more or less at the same time.
>> Water temperature recovers faster than the oil temperature after I
>> power
>> down. At this time I can barely make it to circuit height and then
>> have
>> to level off, build more speed, and then limit my climb with 200 ft/
>> min
>> until I'm in cooler air. The engine has now 32 hours on it, so it
>> might
>> still improve somewhat further, but I don't expect miracles from that.
>>
>> I had to do something.
>> First I made an additional exit in the cowling, under the turbo,
>> hoping
>> to provide more airflow. Whether the airflow in the cowling improved I
>> don't know, but it had zero effect on the water and oil temperatures.
>>
>> Temperatures inside the cowling seem to be ok anyway, no discoloured
>> spark plug indicator labels (still bright yellow), no melted tie-
>> wraps, etc.
>>
>> My conclusion was that the problem is not in cooling of the cowling,
>> but
>> somewhere in the efficiency of the radiators.
>>
>> So then I built a new radiator inlet, somewhat larger than previous
>> one,
>> with a lip to avoid digesting the boundary layer and making sure the
>> inlet receives ram air, angled straight into the airflow, and with a
>> diffuser for which I copied a profile out of a famous book.
>>
>> It was no improvement over my "free style" sleeker inlet and diffuser.
>> None. Very frustrating, as I ruined my nicely shaped and painted
>> original inlet for this.
>>
>> I need to do something, but to avoid ruining again something in
>> order to
>> solve this problem, I need to hear some experiences:
>>
>> 1) A shroud over the cylinders. I don't have it, but instead I have
>> two
>> naca ducts in the upper cowling, curved down to release air aimed at
>> the
>> cylinders.
>> Has anyone ever tried whether the Rotax shroud (or home made shroud)
>> makes any difference? Sure, it will cool the cylinders, but does it
>> have
>> any effect over the water temperature and/or oil temperature? Or is
>> this
>> again going to be a loss in time and effort?
>>
>> 2) In my setup the oil cooler receives exit air from the water
>> cooler. I
>> know there is a "trick" mentioned in the build manual for hot climates
>> to lower the oil radiator 2 inches to receive cold air instead of warm
>> air, but I didn't opt for this as I don't consider our climate as
>> extremely warm, and in winter the oild could actually get too cold.
>> Has anyone tried both options, and did it make much difference? Also,
>> did it have any influence over the water temperature? Relocating the
>> oil
>> radiator will be a large project, and I fear that after that I will
>> still have to limit my climb outs to avoid the water from boiling.
>>
>> Yesterday on the airfield I took a closer look at the Rotax 914
>> equipped
>> Dimona, which is used by the glider club to tow all day long gliders,
>> with full power at 50 knots, in all ambient temperatures. They never
>> have cooling problems.
>>
>> What I saw was shocking. The water radiator is fully exposed to the
>> airstream, no diffuser whatsoever, it is just part of the cowling,
>> as if
>> someone took out some skin of the cowling and fitted the radiator in
>> the
>> resulting hole. The oil radiator is mounted in an angle behind a naca
>> duct (I was taught that a naca duct does not provide ram air and
>> shouldn't be used for cooling a radiator?). Both radiators just dump
>> the
>> warm air inside the cowling! It can't be easier than that.
>> Then, at the bottom, the Dimona has a cowl flap which just opens the
>> cowling to dump *all* air overboard. If it is closed, all radiators,
>> as
>> well as all cowling ventilation, is blocked.
>> How can this system, which looks less sophisticated than our system,
>> while violating all rules and knowledge, work so well?
>>
>> Anyway. At the moment I'm grounded, can't fly like this, and after
>> spending a week trying to improve things with zero effect, I'm out of
>> options and I'm inclined to leave the airplane in the hangar and find
>> another hobby. :-(
>>
>> Seriously, what should I do?
>>
>> Frans
>>
>>
>>
>>
>
>
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