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Cooling issues, once again!
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roberthatton1(at)googlema
Guest

Posted: Sat Jun 05, 2010 2:25 pm Post subject: Cooling issues, once again!

I have been following the cooling topic and wondered what the forum thought about using Evans coolant?  

   

I noticed Kevin uses Evans from his Death Valley flight description, but Mike Parkin threw his away!  

   

I am about to refill my radiators and was considering Evans as the way to go. I am based in Colorado and expect hotter temperatures in the summer than northern Europe and cooler ones in the winter.  

   

I would welcome anyoneâ€™s advice and experiences.  

   

BTW â€“ on my 912UL installation the Oil cooler was lowered and made a dramatic difference â€“ stable temperatures and no sign of overheating when the aircraft was flying in the UK. I am considering lowering the Oil Cooler for my 914 installation for the temperatures get up to the high end of the scale during climb out, but do stabilize in the cruise.  

     

Robert Hatton  

email: roberthatton1(at)googlemail.com  

  

       

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of GRAHAM SINGLETON

 Sent: Saturday, June 05, 2010 9:38 PM

 To: europa-list(at)matronics.com

 Subject: Re: Cooling issues, once again!  

  

  

       

You could be right there Frans. btw theory says that cowl inlet should be much smaller than rad area so that some pressure recovery can happen, also lips must be smooth.

 Graham  

    

         

  

From: Frans Veldman <frans(at)privatepilots.nl>

 To: europa-list(at)matronics.com

 Sent: Saturday, 5 June, 2010 21:27:33

 Subject: Re: Cooling issues, once again!

 

 --> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>

 

 On 06/05/2010 09:26 PM, Rob Housman wrote:

 

 Looking closer to both radiators, It appears to me that the oil cooler

 has closer spaced fins, thicker fluid canals, and an overall smaller

 useful area.

 It might be that this is the reason why lowering the oil radiator also

 causes the water tem/Navigator?Europa-List" ="http://forums.matronics.com" target="_blank">http://forums.matronics.                    &nbsptronics.com/contribution" target="_blank">http://www.matronics.com/contri================

 

 

   

  

  

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rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Sat Jun 05, 2010 2:49 pm Post subject: Re: Cooling issues, once again!

Hi Frans

My 2 cents from someone not yet flying.

First off I have an XS with Monowheel with standard stainless firewall and intercooler on starboard side, both hinder cooling. 

Here is some information. Not in any sort of organized order:

**Gilles did a beautiful job making a cowl for his tiny 914 powered craft. No two holes even in front, only one cooling air baffle intake. I think he has his radiators stacked one behind other. anyway here is some links:

http://contrails.free.fr/engine_aerodyn_radia_en.php

http://contrails.free.fr/tunnel_en.php

http://contrails.free.fr/diap/phpslideshow.php?directory=diapo_capot_if

He says very sucessfull install.

**With Rotax 914 it is best to make sure you are not running too lean. Using a carbon monoxide tester is an awful good solution. Not only can you measure each cylinder when making war emergency power (115%), you can also verify 100% and 85% is OK too. Throwing a little gas on the fire in fact helps keep things cool. I have incorporated a rich switch that activates the enrichment solenoid at will, I suspect 85% on up will run cooler when you enrich a little (computer does it for you over 100% power, best diode isolate your input so as to not hurt TCU). If you are interested will give full details. Again mixture is critical not running too lean at high power setting, mogas with alcohol will run leaner than mogas without alcohol, thus even if 914 was factory jetted, I question just how well the jetting is with the stuff coming out of mogas pump. Main jet, jet needle and needle jet control 85% on up mixture, main jet mostly at full throttle. I am going to run a bit rich and use mixture control to lean to my liking.

**Constipation is a big problem, Ira mentioned using an airspeed indicator to see where high and low pressure area is. You can read here what I am doing:

http://www.europaowners.org/forums/gallery2.php?g2_itemId=28737

I want to be able to cool in worst case scenario, and will warm things up with an oil thermostat and an air plug in the intake of radiator duct (reversed direction fan).

To unconstipate  going to drop aft part of cowl ~3/4 to 1", and widen the exit area of cowl a bit. I will also use two model aeroplane electric motors to exhaust through gills on ground and in climb. Will use a model aeroplane folding propeller  fan in radiator duct to help pressurize duct on ground and in climb. It will be reversible to hinder cooling (and hopeful drag) in cruise. You don't need much amps to cause an awful clog.

**I am going to get my radiator coated with a coating that supposedly increases efficency.

**I will have my exhaust coated with a coating that is supposedly time tested from Rotax research arm, limits some heat going into cowl. If I want to limit more heat going into cowl will wrap exhaust, but makes for harder inspection. BTW Gilles wrapped his turbo.

**I am installing Rotax cooling air baffle. One problem with the baffle is upon shut down it tends to hold in more heat than without the baffle. With my fans, will just let run on low upon shut down.

**Using something like an automobile windshield washer pump and spray head misting radiators with water could keep you cool till you hit on something that works. I have a 2004 Volvo V-70 turbo and it has two, 3 stream spray head mister that does a pretty good job, you would only need one. This is completely off topic, but if you ever get someone tailgating you when driving and there is no need for someone to be doing this, spray your windshield washer, I mean continuous, yes it will cost you a refill but will make the tailgater back away (way annoying to tailgater) and gratifying to you. Have a friend do this to you to see just how well it works.

**Instead of guessing put some temp measuring instruments in various locations FWF, once you get a baseline you can see how you are doing. That goes too for measuring pressures.

**As far as dropping oil radiator, think an awful good idea (or move it), remember Europa radiator is a lot deeper than other MFGs use. 

**My decision to go route of tweaking supplied cowl/cooling system instead of major rethink, is not only time required (ask Paul about speed of such a project), but distinct fooling probably needed after the fact that  it may never be to my liking before I lose interest and ability.

Kudos to Gilles to bringing his cowl/cooling to fruition!

Ron Parigoris

grahamsingleton(at)btinte
Guest

Posted: Sat Jun 05, 2010 2:57 pm Post subject: Cooling issues, once again!

Frans

might be worth doing an oil flow test flight. Paint old engine oil on the fromnt of the cowling, fly at climb speed for a few minutes to stabilze the airflow pattern then land and take photos.

All the EZ gurus do this and they have impressive results, especially Gary Hertzler, he's my favourite guru.



Graham

From: Frans Veldman <frans(at)privatepilots.nl>

To: europa-list(at)matronics.com

Sent: Saturday, 5 June, 2010  11:28:25

Subject: Europa-List: Cooling issues, once again!



--> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>



Gentlemen,



Although my initial cooling issues have been improved upon, I'm not

satisfied at all with the cooling of my 914.



 

  [quote][b]

tonyrenshaw268(at)gmail.c
Guest

Posted: Sat Jun 05, 2010 3:11 pm Post subject: Cooling issues, once again!

Hey Paul,

I'd like to give you a call and don't have your no? Would you be able to beam it over, and your address? Are you a Skype person, and if so, what is your Skype name.

So, how are your mods going on your plane?

Reg

Tony R.



On 06/06/2010, at 2:43 AM, Paul McAllister wrote:



 	  Quote: 	
		   Hi All,

 

 I am curious to know if there are any examples of standard XS cooling set

 up's that do not have the oil radiator lowered that work fine.

 

 Thanks,  Paul

tonyrenshaw268(at)gmail.c
Guest

Posted: Sat Jun 05, 2010 3:25 pm Post subject: Cooling issues, once again!

Hey Frans,

Sorry to hear about your cooling issues, especially after your effort with mods. What is this PUR-foam all about please?? How many hours have you clocked up, and how are you finding the bird??

Reg

Tony Renshaw

On 05/06/2010, at 10:50 PM, Frans Veldman wrote:

 	  Quote: 	

 On 06/05/2010 01:22 PM, Lisbet og Gert Dalgaard wrote:

> Be 100% sure that no air are bleeding out through gaps around your air

> baffles!

 I replaced the entire Europa duct, but it mates with the cowling at some

 point of course. I didn't have the impression that it was very leaky,

 but at the moment I'm waiting for PUR-foam to cure (one side taped off

 of course) to see if there was indeed a leak. I'm hoping there was a

 leak, and I saw some bugs piled up in one corner just before the

 radiator, so that is a hopefull sign. 

 Frans

paul.the.aviator(at)gmail
Guest

Posted: Sat Jun 05, 2010 3:54 pm Post subject: Cooling issues, once again!

H Frans,



I have a few questions. Have you tried 100% power in straight and level flight.  If so, do you get sufficient cooling ?  



If you are able to get sufficient cooling at 100 or even 115% power while flying level then  you know that your radiator capacity is correct and you have issues with the inlet at high angles of attack.

 

Another possibility is that air is flowing out of your NACA vents at  a high angle of attack thus reversing the direction of air flow under the cowling while climbing.  The reason this is a possibility is that the low pressure area moves forward at higher angle of attacks.

 

A couple of suggestions.



1. A gentle flight around the pattern with an 'oil streak' test to see if the diffusers are working as expected.

2. 100% level flight test to see if you have sufficient cooling capacity

 3. Blocking the NACA vents and seeing if what happens in the climb.



Finally, Ron's suggestion of a spray bar is a good one, it will keep you flying until you get this all figured out.



Good luck,  Paul

 

  [quote][b]

Jeff(at)rmmm.net
Guest

Posted: Sat Jun 05, 2010 4:00 pm Post subject: Cooling issues, once again!

Just my two cents worth... Drop the Evans idea. 50 50 runs much cooler and you can get it anywhere. Why risk it. 

 Jeff R.  N128LJ Gold Rush



 

  

On Jun 5, 2010, at 5:18 PM, Robert Hatton wrote:

 	  Quote: 	
		  I have been following the cooling topic and wondered what the forum thought about using Evans coolant?

 

I noticed Kevin uses Evans from his Death Valley flight description, but Mike Parkin threw his away!

 

I am about to refill my radiators and was considering Evans as the way to go. I am based in Colorado and expect hotter temperatures in the summer than northern Europe and cooler ones in the winter.

 

I would welcome anyone’s advice and experiences.

 

BTW – on my 912UL installation the Oil cooler was lowered and made a dramatic difference – stable temperatures and no sign of overheating when the aircraft was flying in the UK. I am considering lowering the Oil Cooler for my 914 installation for the temperatures get up to the high end of the scale during climb out, but do stabilize in the cruise.

 

Robert Hatton

email: roberthatton1(at)googlemail.com (roberthatton1(at)googlemail.com)



 

From: owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com) [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of GRAHAM SINGLETON

Sent: Saturday, June 05, 2010 9:38 PM

To: europa-list(at)matronics.com (europa-list(at)matronics.com)

Subject: Re: Cooling issues, once again!

 

You could be right there Frans. btw theory says that cowl inlet should be much smaller than rad area so that some pressure recovery can happen, also lips must be smooth.

Graham



 

From: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>

To: europa-list(at)matronics.com (europa-list(at)matronics.com)

Sent: Saturday, 5 June, 2010 21:27:33

Subject: Re: Cooling issues, once again!



--> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>



On 06/05/2010 09:26 PM, Rob Housman wrote:



Looking closer to both radiators, It appears to me that the oil cooler

has closer spaced fins, thicker fluid canals, and an overall smaller

useful area.

It might be that this is the reason why lowering the oil radiator also

causes the water tem/Navigator?Europa-List" ="http://forums.matronics.com" target="_blank">http://forums.matronics.                    &nbsptronics.com/contribution" target="_blank">http://www.matronics.com/contri================



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kevann(at)gotsky.com
Guest

Posted: Sat Jun 05, 2010 7:04 pm Post subject: Cooling issues, once again!

Hi Franz,

No, I do not have the cylinder shroud.

My engine now has 180 hrs. Before these last few flights all my flying was 

done at lower, winter, temperatures (I have spent my summers working in 

Alaska and decided to leave the plane in the hanger at KBIH till I get more 

confidence landing this thing.)

My oil cooler has been lowered from the begining, in fact all has remained 

the same except for adding the exhaust wrap and a cabin heater flap off the 

back of the cooling duct.

I just got back from flying today. OAT at KBIH was 38c. At 100knots 

indicated climb the oil stabilised at 230F and CHT at 245. The temps will go 

higher at lower climb speeds, but that is at 100% (not 115%) and 5500rpm.

I can tell that running for very long on the ground at these high OATs will 

not be good.



Kevin

---

Brian Davies

Joined: 10 Jan 2006
Posts: 124
Location: uk

Posted: Sat Jun 05, 2010 11:35 pm Post subject: Cooling issues, once again!

I run have run Evans from new, with completely standard  installation and no cooling problems.  Max OAT I have experienced is  28C.  I suspect some of the problems with Evans have been caused by  switching to it from standard 50:50 without getting rid of every last drop of  the old stuff before using Evans .  The instructions do warn of this  problem.

  

 Brian Davies

 912S Trigear



   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Robert  Hatton

Sent: 05 June 2010 23:18

To:  europa-list(at)matronics.com

Subject: RE: Cooling issues,  once again!

 

  

I have  been following the cooling topic and wondered what the forum thought about using  Evans coolant? 

  

I noticed  Kevin uses Evans from his Death Valley flight description, but Mike Parkin threw  his away! 

  

I am about  to refill my radiators and was considering Evans as the way to go. I am based in  Colorado and expect hotter temperatures in the summer than northern Europe and  cooler ones in the winter. 

  

I would  welcome anyone’s advice and experiences. 

  

BTW – on  my 912UL installation the Oil cooler was lowered and made a dramatic difference  – stable temperatures and no sign of overheating when the aircraft was flying in  the UK. I am considering lowering the Oil Cooler for my 914 installation for the  temperatures get up to the high end of the scale during climb out, but do  stabilize in the cruise. 

   

Robert  Hatton 

email:  roberthatton1(at)googlemail.com

 

    

From:  owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of GRAHAM  SINGLETON

Sent: Saturday, June 05, 2010 9:38 PM

To:  europa-list(at)matronics.com

Subject: Re: Cooling issues,  once again!



 

    

You could be right there Frans. btw theory says that cowl  inlet should be much smaller than rad area so that some pressure recovery can  happen, also lips must be smooth.

Graham

  

     

 

From: Frans Veldman  <frans(at)privatepilots.nl>

To:  europa-list(at)matronics.com

Sent: Saturday, 5 June, 2010  21:27:33

Subject: Re: Cooling issues, once  again!



-->  Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>



On  06/05/2010 09:26 PM, Rob Housman wrote:



Looking closer to both radiators,  It appears to me that the oil cooler

has closer spaced fins, thicker fluid  canals, and an overall smaller

useful area.

It might be that this is the  reason why lowering the oil radiator also

causes the water  tem/Navigator?Europa-List" ="http://forums.matronics.com"  target="_blank">http://forums.matronics.                     &nbsptronics.com/contribution"  target="_blank">http://www.matronics.com/contri================



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erichdtrombley(at)juno.co
Guest

Posted: Sun Jun 06, 2010 9:15 am Post subject: Cooling issues, once again!

Frans,



I have a one off custom FWF that uses the stock engine mount,  water radiator and oil cooler (located one behind the other which in many aspects is close to what you have done).  I had a very similar experience to yours in that I conducted my first flight in January when temps were mild and as summer approached I ran into major cooling issues just as you described.  I do not believe dropping the oil cooler will do anything for you if your design is like mine in that it is properly sealed around the inlet of the water radiator.  Because my water radiator and oil cooler are in line I have sealed the space between them on the top.  The sides and bottom are sealed around the sides of the cowling.  I will try and post a picture of this.  Anyway, what Rob states below about heat transfer is spot on.  You need to look at it as a system.  In addition the oil and water dog house which measures 2.375" x 7.375"  at the inlet, my initial design had two very small round openings (2" diameter) in a location close to the stock cowling.  



Like Kevin I am able to climb out at high power settings (usually 31" MP) to the high teens without issue so long as I don't go slower than 90 KIAS.  This limits the nose high attitude.  Any slower and I will start to overheat.  BTW I live in Las Vegas, NV and we have been know to have a warm day every now and then.  Yesterday we hit 108 deg F.   



This is what I did to solve my cooling problem which was pretty straight forward: I enlarged the 2" diameter holes to create a horizontal teardrop.  The extra air flowing over the top of the engine was sufficient to keep it cool both on the ground and during climb.  I also use Evans cooling which did increase my temps by about 10 degrees C over 50/50 water & antifreeze but provides a higher boiling point.  I was initially tempted to lower the oil cooler, however, this would have been a major modification with my design, so that was out and it was doubtful from a system perspective if this would have really helped.  It is another matter if I had the stock Europa cowling since there is a large gap at the bottom of the cowl and lowering the oil cooler fills this space preventing the air from bypassing around the radiator and oil cooler.  I didn't have this issue with my design as noted above.  So, two options were left, increase the size of the oil cooler and radiator, or open up the round holes to provide more flow over and around the engine.  The latter was the easiest to option and worked out well for me.  My guess though is that a larger radiator and oil cooler, retaining my original 2" holes would result is the least drag option.  Keep in mind I am near red line during climb usually around 125 deg C. on oil temp which leads CHT.   I hope the above is helpful.



Good luck.

Erich Trombley

N28ET Classic Mono 914  

Time: 12:38:50 PM PST US

From: "Rob Housman" <europa(at)hyperion-ef.com>

Subject: RE: Cooling issues, once again!



While it is true that "heat transfer is directly proportional to temperature

difference" that does not tell the whole story.  First, remember that the

relevant temperature difference is the difference between the temperature of

the fluid on the inside and the air on the outside, and even with pre-heated

air the second radiator could have the same delta T as the first radiator.

I'll grant you that there is probably a difference, however.

Also relevant, and non-trivial, are the area of the heat transfer surface,

the flow rate of the liquids inside the heat exchangers (radiators, in

common aircraft and automotive parlance), the flow rate of the air outside

these heat exchangers, the heat transfer coefficients for each of the fluids

involved, the heat transfer coefficients of the materials from which the

radiators are made, the effect of any scale or similar deposits on the heat

transfer surfaces (both inside and outside), Reynolds numbers for the

flowing fluids (a function of flow rates and fluid properties), and the

physical properties the radiators and of the coolant and oil flowing within

the heat exchangers.

Having said all of that, there is no doubt that "re-using" the cooling air

will affect heat transfer within the radiator using pre-heated air, and this

is undoubtedly why Europa recommend placing one below the other.

Best regards,

Rob Housman



Irvine, CA 



Europa XS Tri-Gear



A070



Airframe complete

From: owner-europa-list-server(at)matronics.com

[mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Robert Borger

Sent: Saturday, June 05, 2010 11:02 AM

Subject: Re: Cooling issues, once again!

Paul,

I don't see how it can.  Simple thermodynamics is against it.  Heat transfer

is directly proportional to temperature difference.  Both radiators are at

about the same temperature.  Once the air has been heated by the first

radiator its ability to accept heat from the second has been greatly reduced

if not eliminated.  

And this is assuming that the area below the radiators has been sealed so

that the air goes through the radiators and not under them, doing no good at

all.

Check six,



Bob Borger



http://www.europaowners.org/N914XL



Europa XS, Short Wing, Intercooled Rotax 914



rlborger(at)mac.com



Cel: 817-992-1117

On Jun 5, 2010, at 11:43 AM, Paul McAllister wrote:

Hi All,



I am curious to know if there are any examples of standard XS cooling set

up's that do not have the oil radiator lowered that work fine.



Thanks,  Paul

  



____________________________________________________________

New Era Diets (SHOCKER)

Simple weight loss secret to lose 12 pounds in 30 days

consumershealthreports.com  [quote][b]

frans(at)privatepilots.nl
Guest

Posted: Sun Jun 06, 2010 11:13 am Post subject: Cooling issues, once again!

On 06/06/2010 07:07 PM, Erich Trombley wrote:



 	  Quote: 	
		   I have a one off custom FWF that uses the stock engine mount,  water

 radiator and oil cooler (located one behind the other which in many

 aspects is close to what you have done).  I had a very similar

 experience to yours in that I conducted my first flight in January

 when temps were mild and as summer approached I ran into major

 cooling issues just as you described.


	


It looks indeed like your setup is quite similar to mine.

Just like you, I can't drop the oil cooler without major modifications.



 	  Quote: 	
		   This is what I did to solve my cooling problem which was pretty

 straight forward: I enlarged the 2" diameter holes to create a

 horizontal teardrop.  The extra air flowing over the top of the

 engine was sufficient to keep it cool both on the ground and during

 climb.


	


I have two naca ducts in the top cowling with a diffuser angled down so

it dumps the air on top of the cylinders. After some testing, I believe

that in my situation the answer should not be found in increasing the

cowling airflow. Reasons are:

1) There are no signs of elevated temperatures inside my cowling. No

color changes, no melted plastic parts, etc.

2) I had the large 3" stock cowling inlets plugged, but openen them

again in the hope that this would enhance cooling. Well, it didn't.

There was a very slight improvement in ground cooling, but not in flight.

3) As the Rotax engine is mainly water cooled, it is more efficient to

cool it by water than by air. All air taken away from the front of the

airplane reduces pressure recovery and results in more drag. So we

should try to use the cooling air as efficiently as possible. True, if I

remove the cowling completely the engine runs much cooler. But how much

drag are we creating with that?



The more I learn about this subject, the more clear it becomes to me

that two radiators in series is a bad design. The front radiator has no

free exit, the air flow is impeded by the second radiator. This severely

reduces air flow through the radiator. Less airflow is less cooling. The

second radiator receives hot air from the first radiator. Less

temperature difference is less cooling. Also this radiator suffers from

reduced airflow because of the drag of the first radiator.



So, as it already turned out that two radiators in series doesn't work

well in my case (and in the case of the majority of the forum members)

I'm going to change it.



(In your situation it works, but even with your enlarged cowling

openings, you are still balancing on the red line and have to limit

climbing to less than Vy. It is better than what I have now, but now I

have to work on it anyway, my goal is to solve the issue completely.)



The idea is now to take the oil radiator completely away, so the water

radiator can vent the air freely. For the oil radiator I will take a

smaller one (everyone reports too much oil cooling once the oil cooler

is lowered and it is no longer fed with hot air), fit it somewhere else

in the cowling, and connect it with a scat tube to a dedicated air inlet.



Additional advantage is that I can put a butterfly valve in the scat

tube and so reduce the cooling air for the oil cooler in winter (or

during warm up), which I think is better than a thermostat (less oil

line connections, and less drag: we are not going to spend energy to

drag air through a radiator while we actually don't want to cool the

stuff inside at all). For the moment I will dump the exit air from the

oil cooler inside the cowling. The 914 equipped Dimona does it that way,

and it tows all day long gliders with full power at no more than 50

knots, in hot weather, without any cooling issues. If really needed I

can give it a dedicated output, but for the moment I will try it this way.



The Rotax manual says that the water radiator releases 30 kW and the oil

cooler 7 kW. So, the oil cooler accounts only for about 20% of the total

heat release. I think it is a good idea to separate it totally from the

water radiator.



Thanks for sharing your experiences!

Frans

frans(at)privatepilots.nl
Guest

Posted: Sun Jun 06, 2010 11:40 am Post subject: Cooling issues, once again!

On 06/06/2010 12:49 AM, rparigoris wrote:

 	  Quote: 	
		   I have incorporated a

 rich switch that activates the enrichment solenoid at will


	


A good idea. I like it for emergency use, but to use a richer mixture to

solve cooling flaws is something I consider a last resort.



 	  Quote: 	
		   mogas

 with alcohol will run leaner than mogas without alcohol,


	


Good point. I use mogas, but haven't bothered too much to see if there

is alcohol inside.



 	  Quote: 	
		   Constipation is a big problem, Ira mentioned using an

 airspeed indicator to see where high and low pressure area is.


	


Good idea as well. Guess it is time to source ebay for a used ASI.



 	  Quote: 	
		   I will also use two model aeroplane electric motors to exhaust through

 gills on ground and in climb.


	


Well, I'm not too fond of this idea. It is somewhat strange to have to

use fans in a vehicle that has already a large big fan in front, and

which moves fast by nature. There is plenty of airflow available, it is

just a matter to find a way to let physics do the work for you.



 	  Quote: 	
		   I will have my exhaust coated with a coating

 that is supposedly time tested from Rotax research arm, limits some

 heat going into cowl. If I want to limit more heat going into cowl

 will wrap exhaust, but makes for harder inspection.


	


Keep in mind that heat release is actually a good thing. Heating the air

inside the cowl increases the volume of the air, and thus creates extra

pressure on the exit. This reduces drag. Jet engines work that way as

well. 

Further, the cooler the air escaping from the exhaust, the less noisy it

is, and the less turbulence it causes. This again results in less drag.

With a proper airflow inside the cowling (from top to bottom) you are

using waste cooling air from the cylinders to cool the exhaust tubes.

This heated air should just go to the exit, and nowhere else. If this is

the case, it is worth cooling the exhaust as much as possible.



 	  Quote: 	
		   Using something like an automobile windshield

 washer pump and spray head misting radiators with water could keep

 you cool till you hit on something that works.


	


This means I would have to install a water tank, carry water as ballast,

install electrics, etc. I think in the same time I could relocate the

oil cooler. If the vendors cooperate, I will be flying again within a week.



Frans

zwakie

Joined: 03 Aug 2009
Posts: 157

Posted: Sun Jun 06, 2010 1:08 pm Post subject: Re: Cooling issues, once again!

Frans, sorry to hear about your oil-cooling issues - but it lead to an interesting discussion that I follow with great intrest.



Next time we're both on the field, could you have a look at my setup? I have some ideas that I would like to run by you...

_________________
Marcel Zwakenberg
Europa XS TG || 912ULS || PH-SBR

rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Sun Jun 06, 2010 1:56 pm Post subject: Re: Cooling issues, once again!

Hi Frans



Sounds like you are getting off to a good start.



A few points to make, and a few I disagree with



**Ask any Rotax distributor in the know, they want a 914 to run well below edge of redline for longevity. Not too cold, but near the lower end is preferable. I think we can agree on this. Lockwood loves the temps on his aircam in the air, but hates them in water making a long taxi (twin 914 or 912S pusher)

**Now here is where I don't agree with you. True there is a big fan upfront, and seems foolish to also add little fans to unconstipate the cowl. In a properly designed cowl/cooling system I agree. I don't believe the Europa has a properly designed cooling system. I don't think it is too too draggy, but taxi on ground and climb it is for certain less than ideal. Unless you increase drag more than desired all the time, I rather dump some amps to do the deed on ground and in climb than engineer an entirly new system. It also gives a side benefit of being able to cool down cowl after shut down. Europa uses a smaller frontal area radiator than many other Rotax installations with same total area. This means you need a faster flow. In cruise you have that faster flow, but let me see you make that fast flow on ground and in climb? Lets see how Diamond works at 50 knots with Rotax radiator? I forget, perhaps Karl?? used a larger frontal area radiator with good results i think with intake similar to yours. Also some not only have larger frontal areas, they have more total area. Anyway I am installing a fan that can in-fact create a lot faster airspeed than the prop in those configurations ever could by themselves. You make a pretty weak case that temps are fine in cowl because you don't see any plastic discolored. My gut feeling is after a hundred hours you probably will. Plastic takes a while before it becomes discolored and brittle in many instances. Measure please so there is no doubt. I bet you find stalled air not making its way out as fast as you would like (I think upper aft a good place it gets stuck). The exit area of Europa is less than ideal, especial when you dump intercooler air in there. I disagree that heating cowl air is a good thing. Yes on fast glass, or a P-51 you can accelerate air faster and easier to airspeed on exiting and decrease drag a bit. That said you could close all intakes or exits on cowl and reduce drag a little more, of course this does not benefit cooling which is an issue. If cooling was not an issue, then drag reduction is a good thing to chase. On Europa you will almost for certain heat the exhaust and turbo heats darn engine up. There is not a trivial amount of BTUs given off from the exhaust and turbo, it can easily heat motor where through water, oil, air and gas (enough carbon monoxide per Rotax recommendations) cooling, will not enough to lower the temps to liking. There is enough intake air charging through Europa cowl, yours included where if you are heating it alot, it means air is getting constipated. I think it is very safe to say the discharge of a typical stock XS Trigear exit air or your plane is nowhere near as good a design as a P-51 or Gilles exit design. Measuring temps and pressures is best way to make informed decisions. Be more concerned on ground and in climb than in cruise. With top cowl off there is not much in way of constipation. The two gill fans are easy to try, it semi replicates having the top cowl off. The motors are probably under 10 bucks for the two, and props and hubs about the same. If you find they lower temps and pressures leave them in place. If they do nothing then take them off. Same goes with rich switch. If you can climb between 85 and 100% power and lower temps, then that is a good thing. Colors of spark plugs running mogas is not too reliable of an indicator. running 100LL is better, but you would need to shut down after a run at 100% and 115% to measure to get most reliable reading. Carbon monoxide the most accurate and reliable method. True burning a tad more fuel with rich switch, but way way easier on motor until you can verify with carbon monoxide detector. Soften heads and that =s BIG $. Also a good thing to fool with, if you see at 100% power when you richen the EGTs first go up before they go down, or even stay still for a bit, you are either lean of peak or at peak. A leak where you have a slight high EGT can be addressed too. Alcohol in gas will lean mixture compared to fuel with no alcohol. Type 64 carb on 914 does not compensate mixture via a 02 or carbon monoxide sender, they are fixed. Run alcohol, will run leaner. On a car run more alcohol, will compensate if it uses a o2 sender system.

Anyway unconstipating air will most likely benefit your cooling. Now if you are thinking you can use big fan upfront to cool in the worst conditions you will see and have motor running cool enough, I am all ears. BTW  against popular belief according to factory before shake up, cowl gills do in fact evacuate air from cowl in climb. Flying with doors off (photo shoots)  prove that (reached out and felt warm air coming out). Also allow s for better cooling upon shutting down motor.

In your case I think first is unclog the exit of the radiator by moving the oil radiator. 

As far as the water cooling goes, make something pretty temporary, this way instead of overheating that is pretty terrible on motor, you can cool with the water till you figure out. Same goes with rich switch, same goes for gill fans. I would hate to see a damaged motor.

On a 85F day at sea level, I want to be able to take off at 115% power and climb at best angle of climb for 30 seconds and then best rate of climb in fine Airmaster pitch for another 3.5 minutes, then 100% power till I get to 18K near gross and have temperatures happy. I also want to be able to taxi in 85F for longer than I care for and not only be able to take off, but have temps at a reasonably low level.  Thats is my goal.

Have ability to cool worst case, then oil thermostat to keep oil temps warm automatic, and have reversible radiator intake duct to act as a cowl flap, constipate amount of air flowing through and reduce drag a bit and keep oil and coolant temps up. First start on a cool day will warm up faster with intake duct clogged with a low powered reverse fan as well.

Good luck, please keep us up to date.



Ron Parigoris

mikenjulie.parkin(at)btin
Guest

Posted: Sun Jun 06, 2010 11:35 pm Post subject: Cooling issues, once again!

Frans,



 	  Quote: 	
		  >For the oil radiator I will take a

>smaller one (everyone reports too much oil cooling once the oil cooler

>is lowered and it is no longer fed with hot air), fit it somewhere else

>in the cowling, and connect it with a scat tube to a dedicated air inlet.


	


Please take care here.  On my installation it is not just the oil that runs

cool, the whole engine runs cooler than desired in the cruise.  When people

are reporting that the oil is too cold, I think many have lower CHT/Coolant

temperatures as well.  With the original tandem cooler arrangement I found

that the temperature indications were virtually identical at all times.

With the oil cooler lowered the oil temp does lag the water/CHT temps but

once stabilised, water and oil read much the same.  I have oil, water and

CHT gauges.



Regards,



Mike



Do not archive

frans(at)privatepilots.nl
Guest

Posted: Tue Jun 08, 2010 4:24 am Post subject: Cooling issues, once again!

On 06/06/2010 11:56 PM, rparigoris wrote:

 	  Quote: 	
		   **Ask any Rotax distributor in the know, they want a 914 to run well

 below edge of redline for longevity. Not too cold, but near the lower

 end is preferable. I think we can agree on this.


	


I don't necessarily agree with this. There is a practical reason to

limit the temperatures of the cylinder heads: above a certain

temperature the aluminium softens. But you can't reverse this reasoning:

there is no additional benefit to get further away from this redline

than necessary. In fact, a lower temperature worsens the efficiency of

the engine, causes worse fuel atomization, etc.

The same with the oil temperature. The red line is there because above a

certain temperature the oil starts breaking apart. But you shouldn't

stay further away from this red line as neccessary. I think we all know

that colder oil is not working well, that is why we have a lower limit

on the oil temperature after all.

I wouldn't see why running well below the edge would increase the

longevity. The heads melt or they do not.



 	  Quote: 	
		   **Now here is where I don't agree with you.


	


You have some points here. It is just that I think that having to rely

on electrical fans is not elegant, and electrical fans can fail. I

prefer to make the best use of the air flow we already have by the

nature of flying, but there is no real wrong or true here.



 	  Quote: 	
		   I disagree

 that heating cowl air is a good thing.


	


I didn't say that. I said: "heating up the air before it leaves the

airplane is a good thing".

With other words: you should try to heat the air up on its way to the

exit... but make very sure that it exits indeed and doesn't linger

around in the cowling. With a proper airflow from top to bottom, the

turbo and muffler are the very last things the air will encounter. It

could be beneficial to pick up heat from it as much as possible, to

increase the air volume and have something to offer to the void behind

the cowling or cowl flap. The more volume of air you exit, the less drag

you have... until at some point you even get propulsion from the hot air

exiting the cowling (but true, we aren't likely to achieve this stage

with an Europa).



BTW, thanks for the information you sent!!



Frans

rparigoris

Joined: 24 Nov 2009
Posts: 791

Posted: Tue Jun 08, 2010 6:59 am Post subject: Re: Cooling issues, once again!

Hi Frans

I hear where you are coming from, and somewhat agree. In a world where the Mfg. did their homework and published the proper info, and you had gages that spoke the truth running near redline is not too too bad a thing.

In real world Rotax found that oils that they blessed, and temps they published can cause problems. Not only did they change some coolant temps but wanted you to monitor more info if you use 50/50 mix. Now as far as instruments, an error on the low side can occur easily. In europa and many cowls, inside temps can increase to point where regulator, ignition modules, plug wires and other wiring can and do take an extra beating the hotter they get.

Ron Parigoris

frans(at)privatepilots.nl
Guest

Posted: Tue Jun 08, 2010 2:22 pm Post subject: Cooling issues, once again!

Hi Guys,



It looks like I might have solved my cooling problems!



What I did:

I took the oil cooler completely out of the duct. The cooling duct now

only supplies air to the water radiator.

The oil cooler is now mounted on the starboard footwell. It is fed with

cold air via an internal simple wedge shaped diffuser, connected to a 2

inch scat-tube that runs to the front of the airplane, to a 2 inch hole.

(2 inch is pretty minimalistic for this huge oil cooler but a 2 inch

scat tube is what I found in my airplane surplus box.) The warm air

exiting the oil cooler is simply dumped inside the cowling (and can

still absorb some more heat there).

I closed off the front round 3" air inlets completely to reduce pressure

inside the cowl. This to further promote air flow through the more

usefull air inlets. (For cylinder cooling I have two small naca inlets

in the top cowling aimed at the cylinders).

I built an exhaust augmenter to suck the warm air out of the cowling.



So, this evening we ground tested the system.

First thing we noticed was that it took an unusual long time to warm up

the oil. Also the water temp was lagging quite a bit.

After the engine was warmed up sufficiently I revved the engine up to

4200 rpm. In previous tests I used this setting to measure the time

until something reached red line (usually water and oil touched the red

line at about the same moment).

Well, this time I couldn't reach any red line with this power setting!

Temperatures just stabilized in the middle of the green zone. Unbelievable.

So, after some time I decided to just give it all. Full power.

It took two minutes before finally the oil reached the caution zone. The

water was still in the green zone at that time.

I let the RPM drop, and the oil temperature came down again.



So, at least the ground cooling problems seem to be over. (Ok, I should

test again with really hot weather, but it looks like that that is not

going to be a problem.) This is with a minimal amount of air stolen from

the front of the airplane: Two naca ducts for cylinder cooling, one 2

inch hole for the oil cooler, and the trimmed down cooling duct opening

for the water cooler. Far less than the Europa normally has, so it

should be a relatively very low drag setup.



Whose idea was it to have the two radiators behind each other? I think

this was a grave design error.



If weather cooperates, we can tomorrow do some flight testing. I will

let you know.



Frans

fklein(at)orcasonline.com
Guest

Posted: Tue Jun 08, 2010 2:38 pm Post subject: Cooling issues, once again!

On Jun 8, 2010, at 3:16 PM, Frans Veldman wrote:



 	  Quote: 	
		   I built an exhaust augmenter to suck the warm air out of the cowling.


	


Frans,



A couple of photos, interior and exterior, of your augmenter would be  

much appreciated.



Looks like you've solved your cooling problem!!...congratulations,



Fred

frans(at)privatepilots.nl
Guest

Posted: Wed Jun 09, 2010 9:09 am Post subject: Cooling issues, once again!

On 06/09/2010 12:16 AM, Frans Veldman wrote:



 	  Quote: 	
		   If weather cooperates, we can tomorrow do some flight testing. I will

 let you know.


	


Flight testing complete. Could take off at 115%, without any

temperatures increasing during the prolonged climb out at 115%, with 75

knots. Water and oil stabilized at 90 C. This was with the cowl flap

halfway closed, and an OAT of about 20 degrees.



Can't believe what a difference it made to split up the two radiators.

(This is more than just "lowering" the oil radiator: they now don't

share any cooling air anymore). Amazing that just a 2 inch hole with

cold air for the oil cooler is doing much more than sending all the air

from the water radiator through the oil cooler.



Now the oil radiator is gone from the duct, and I have surplus cooling,

I can slim down the cooling duct and tunnel, and probably gain a few knots.



I think the lesson to be learnt here is that the combination of oil

cooler and water radiator is too restrictive to the cooling air. You can

compensate this poor cooling by promoting air flow over the engine, but

this is more costly in drag terms than to just give the oil cooler a

dedicated air inlet of 2 inch.



Frans

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