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RV-12 ULS Winterization Kits from Van's

I have one of these. The oil cooler portion works fine as a supplement to my oil thermostat to keep the oil temps in the green. The radiator cooler is too small for flying in conditions less than about 35 F. I like the simplicity of the design of the radiator cooler, but it is inadequate in my climate, even at the maximum setting. I was hoping to avoid the installation of a Bender Baffle, but I think that is my only option at this point.
 
COMMENTS ONLY - -

If you use a Thermostasis Oil Therm, your oil is good. It is confusing, but the temp we see on the display is the oil temp at the engine, not the tank. The "Bender Baffle" as some call it, has been my best mod for cold weather comfort. I have scheduled a Flyout for tomorrow. It will be about 18 degrees when I take off. I will be comfortable heat-wise. Once you greatly slow the air-flow thru the rad., it warms the engine coolant, and slows down the air SPEED going thru the rad. That combination gives very good heat. Yes, it takes a few hours to build the "Heater Damper Door", but worth it if you want to fly in cold weather.
 
If you use a Thermostasis Oil Therm, your oil is good. It is confusing, but the temp we see on the display is the oil temp at the engine, not the tank. The "Bender Baffle" as some call it, has been my best mod for cold weather comfort. I have scheduled a Flyout for tomorrow. It will be about 18 degrees when I take off. I will be comfortable heat-wise. Once you greatly slow the air-flow thru the rad., it warms the engine coolant, and slows down the air SPEED going thru the rad. That combination gives very good heat. Yes, it takes a few hours to build the "Heater Damper Door", but worth it if you want to fly in cold weather.

The Thermostasis kit has proven to be very popular. John was one of the early installers, and worked with us to develop the kit.

One advantage is that it is a year round package that doesn't need to be changed as the temperatures change.

The only disadvantage is that it is definitely a higher price point than a metal plate over the cooler.

Steve
 
The Thermostasis kit has proven to be very popular. John was one of the early installers, and worked with us to develop the kit.

One advantage is that it is a year round package that doesn't need to be changed as the temperatures change.

The only disadvantage is that it is definitely a higher price point than a metal plate over the cooler.

Steve

This kit that Steve sells is a must have.
 
Thank you for the feedback! Yes, I have the Thermostasis thermostat and the Aircraft Specialty hoses. It is a great system for heating up the oil faster.

I am confused as to why the temp at the oil tank is relevant, since the sending unit is located on the oil pump. My oil temp gauge reads 180 F most of the time, and the Rotax operating manual section 2.1 states that the normal operating temperature should be between 190 to 230 F. I added the Vans oil cooler baffle to get the temps into the green, which I could not do because the thermostat appears to open at 180. I would assume that Rotax would calibrate the appropriate oil temps based on where the sensor is installed.
 
Will try to answer oil temps -

Rotax wants the oil to be at that temp to keep water from forming in the system. If you have a Thermostasis, then the oil is getting into a needed temp range IN THE TANK. Since your display is reading the temp at the engine, it does not represent what temp the oil is in the tank. On very cold days, the oil going into the engine may appear much lower, but that is because cold oil is being blended at the Therm and goes back to the engine cooler than it actually is in the tank.

Hope that makes some sense.
 
The oil temp sensor is located at the oil pump housing, reading the temp of the oil as it enters the engine.
The oil cooler on the RV-12 is connected in series between the oil tank and the oil pump inlet, so if the oil temp on the indicator is at least in the bottom of the normal range, the oil temp in the tank is probably even higher.
 
GOOD EXAMPLE TODAY - - - -

Was about 4 degrees F at Alt today. I have Thermostasis. Oil temp at engine was 153 degrees on display. NO PROBLEM. Oil in tank is between 195 - 205 degrees. Very cold oil from cooler was blending with warm oil thru Therm, and 153 degrees was going back to engine.

1zf3eae.jpg
 
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Was about 4 degrees F at Alt today. I have Thermostasis. Oil temp at engine was 153 degrees on display. NO PROBLEM. Oil in tank is between 195 - 205 degrees. Very cold oil from cooler was blending with warm oil thru Therm, and 158 degrees was going back to engine.

John - is 200F CHT accomplished by blocking off coolant radiator? Good trick with near 0F OAT...
 
Yes - - -

Another design of mine. Many call it the "Bender Baffle". That is why I can fly comfortably, even at 4 degrees outside temp. Nice warm air comes from the rad. by forcing the temps up, and slowing the flow down. It also helps warm the entire engine.
 
Thanks for the input. I'm still confused though. If Rotax wants the temp sender on the oil pump, and specifies a recommended range of temperatures, why would you be comfortable flying below the recommended temp at the oil pump? You can get the water out of the tank, if the tank oil is hotter, and that is good. But aren't there other reasons why you would want the oil temp at the oil pump to be within Rotax specs? Does the temp affect the flow characteristics of the oil? If the oil is spec'd to be at a certain temperature before it enters the engine, there's gotta be a reason I would think. Thanks again for your patience with my questions! :)
 
Will try - -

I don't believe Rotax needs the oil at the spec temp going into the engine, just need it to warm up at some point to stop moisture build up. They want the oil at 122F to take off at WOT, so 153 is fine in this cold air case. The Thermostasis is great for warm or cold weather warm up. The oil will certainly get cooled off by only slowly going thru the cooler, but it will still blend as needed to keep working well.

Also, adding this. I don't think Rotax ever planned on someone like me adding a thermostat into the system. They wrote the oil temp spec assuming it would all flow thru the cooler and not go thru what I designed. It works, and works very well.
 
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It seems to me that if the oil-cooler-bypass thermostat is set at 190 degrees F and if the oil temperature sensor is located relatively close downstream of the thermostat, then the oil temperature should be 190 degrees or more. Since the oil temperature is only 153, then it seems that the thermostat is not working right. Why is the thermostat not opening to bypass the cooler? Or am I not understanding how it works?
 
The thermostatic valves typically used on Rotax installations are unable to shut off all oil flow to the oil cooler. This is a safety feature to prevent the oil in the cooler circuit from ever getting super cooled and potentially becoming so viscous that it would restrict oil flow if temperatures rose and the cooling capability was needed during the flight. A Lycoming engine oil cooler circuit works the same way.
So if the residual flow is being cooled too much because the OAT is very cold, even the use of a thermostatic valve will never bring the temp up to the normal range.

The Rotax 912 operating manuals says....

Avoid operation below normal operation oil temperature
(90 to 110 ?C / 194 to 230 ?F)


This temp is what you see on the gauge. Not what you think the temp is reaching in the tank.

The oil cooler cover plates were developed to give operators a simple means of elevating the oil temp. In very cold conditions it may still not be possible to achieve the minimum recommended, but the closer you can get to that, the better.
 
Joe - -

INITIAL NOTE : The Thermostasis unit is considered a 98% bypass. Not at all like the automotive designs which are considered 10% bypass.

The Therm forces oil to go thru the cooler when the desired temp is reached. Oil comes back from the cooler TO THE THERM and is blended with hot oil from the tank and sent to the engine. The tank oil can be 200, but the blended oil going back can be 153 as you saw on my display when it was VERY cold outside.

I understand this is a confusing issue. There should be a tank temp option which would help everyone understand how a Therm affects the flow and blending.
 
I understand that thermostat bypasses between 90 and 98 percent of the oil around the cooler and up to 10 percent of the oil goes through the cooler. My RV-12 does not have an oil thermostat. I suspect that if 90 percent of the oil cooler were blocked off, then the oil temperature would be greater than 153 F, even if it were 0 F outside. But do I want to fly in those conditions to find out? :D
 
I do understand how it works John (we actually have one installed on the RV-12iS).

The valve is plumbed into the system so that the oil pump pulls oil either directly from the oil tank (when the oil temp is cold) or from the oil tank through the oil cooler and directly from the tank, with this ratio controlled by the variable valve within the unit.

Depending on the actual oil temp, the thermostatic valve varies the amount of oil sent through the oil cooler but if the OAT is very cold it can not shut it off enough to keep the oil temp within the green as the photo of your oil temp indicates.

Bottom line.... if the valve where able fully control the oil flow through the oil cooler it would be able to deliver oil at the valve rating of 190 F. (or at 205 F if that unit were being used).
Since it doesn't, it doesn't matter what the ratio of bypass is (BTW I have never seen 98% published anywhere).

So it can mean only two things....

- Either that the engine isn't able to heat the oil enough to get it up to 190 because of the cold OAT... even if the oil cooler is barely doing any cooling

or

- There is still too much cooling taking place at the oil cooler even if the thermostatic valve is installed and doing the best it can to bypass the oil cooler.

My opinion is that it is the second one because if you partially block the oil cooler it raises the oil temperature.
 
Scott - -

You likely do not get to, or want to, fly in very cold weather, but here is what happens. Even in cold weather the 98% bypass Thermostasis directs almost all oil thru therm back to engine, with almost none going thru the cooler. After initial start up if you watch the oil temp in warm or cold weather you will see the oil temp go up to approx. thermostat value, then it pauses, and quickly starts back down. That is when the therm closes and forces some of the oil to go thru the cooler, which is why the indicated temp goes down fast, but then stabilizes, until it determines the blend level needed to keep the tank temps at therm value. From then on, you are seeing the blended return temp. The colder the weather, the lower the temp you see on the display. The tank is still at therm value temp.

I would suggest you call Thermostasis and talk to the owner. I am sure I have it correct.
 
I do understand how it works John (we actually have one installed on the RV-12iS).

Scott,

That?s awesome news to hear. It appears that Vans has come to the conclusion that a thermostat is a very worthwhile addition to the rotax engines in cold weather climates.

We have been selling a complete thermostat install kit since March, 2014 for the 912ULS rv-12 Aircraft. Unfortunately SLSA builders have repeatedly been told that there is no data to support installing a thermostat. Since Vans now appears on board with the idea of the Thermostasis, let?s work together to make it available for SLSA customers. We are already utilizing the same thermostat and have figured out the hose routing and lengths to fit into the cowl well. Also, there is detailed documentation for the installation.

It would be a great way to allow all the SLSA owners in cold climates the option of installing a thermostat.

Steve
 
Scott,

That’s awesome news to hear. It appears that Vans has come to the conclusion that a thermostat is a very worthwhile addition to the rotax engines in cold weather climates.

We have been selling a complete thermostat install kit since March, 2014 for the 912ULS rv-12 Aircraft. Unfortunately SLSA builders have repeatedly been told that there is no data to support installing a thermostat. Since Vans now appears on board with the idea of the Thermostasis, let’s work together to make it available for SLSA customers. We are already utilizing the same thermostat and have figured out the hose routing and lengths to fit into the cowl well. Also, there is detailed documentation for the installation.

It would be a great way to allow all the SLSA owners in cold climates the option of installing a thermostat.

Steve

The airplane it is on is an E-LSA (experimental) RV-12, because we have a lot more latitude in regards to general testing than with an S-LSA
It is being evaluated so it is not yet a sure thing for the future but a good possibility, but it if it happens for S-LSA, it will still be a while.

Our experience is that it does help with reducing warm-up time but it doesn't have a huge influence on elevating in-flight temps.

Based on Johns comments, maybe we need to add a bit more instrumentation to see what the oil temps are doing.

If it does eventually get approved as an option we will probably have a kit of our own that we will offer.
 
Scott - -

Thanks for being involved. I can tell you for sure that even in 4 degree F temps, the oil gets up to therm value as indicated on the display before closing some and then blending the return oil and causing the indicated temp to fall some.

It does not offer any help in warm weather other than to warm it up faster. Once the therm is closed, you get full flow thru the cooler. I don't feel it hurts even in hot weather, but well worth the cost for quick warm ups at any temps.

If you have installed one, then watch the temp very closely on take off and climb out. Keep watching until it starts to close and then it will stabilize at lower various temps depending on demand and outside air temps.
 
Our experience is that it does help with reducing warm-up time but it doesn't have a huge influence on elevating in-flight temps.

Scott,

That's a very interesting data point and very different than the data we have seen from approximately 50-60 Thermostasis installations.

It probably doesn't make much sense to install a Thermostasis kit ONLY to reduce warm up times. If that is what you are achieving with your installation, I definitely see the reason why Van's may or may not see the benefit to offering a kit.

However, here is some actual real world data that we have from our installation package. Some of this data is from the 190 degree unit, and some from the 205 degree unit. Almost all the kits we have sent out have been for the 190 degree unit. A few customers had already purchased the 205 unit on their own, so we just built the hoses for them. We have received lots of feedback regarding the unit and it all is very similar to the data shown below.

ATMOSPHERIC CONDITIONS

Temperature -2 Celsius on ground, -13 Celsius in flight

Warmup time on ground from 60 to 122 degrees

Without Thermostasis = 11 minutes
With Thermostasis = 6 minutes


Inflight Temperatures

Without Thermostasis temperature drop to 122 degrees in long reduced power descent
With Thermostasis temperature around 200 degrees in long reduced power descent


Cruise temperatures with thermostasis at -13 Celsius were in the 180-190 degree range."

wp6d82ce03_06.png
 
Inflight Temperatures

Without Thermostasis temperature drop to 122 degrees in long reduced power descent
With Thermostasis temperature around 200 degrees in long reduced power descent


Cruise temperatures with thermostasis at -13 Celsius were in the 180-190 degree range."

wp6d82ce03_06.png

Any idea why this doesn't jive with the experience John is having?

Was about 4 degrees F at Alt today. I have Thermostasis. Oil temp at engine was 153 degrees on display. NO PROBLEM. Oil in tank is between 195 - 205 degrees. Very cold oil from cooler was blending with warm oil thru Therm, and 153 degrees was going back to engine.

1zf3eae.jpg
 
Scott - -

Power demand is an important factor. Notice I was not demanding much power, so less warm oil was involved with the blending on return, and oil going even slower thru the cooler makes the blend even cooler. If I run the engine harder, the return oil does warm up more on return to engine.
 
John, I suggest that you cover up the top 1.5" or 2" of the oil cooler with duct tape as an experiment to see what affect that has on oil temperature in very cold weather. I suspect that the temp will go up to the thermostat set point. If the temperature goes up higher than the thermostat set point, then too much of the oil cooler is covered up.
 
Joe - -

No reason to. Oil in the tank is approx. therm value, and that is all that is important. Agree, your test could warm up the oil at then engine, but it is just not important.
 
Power demand is an important factor. Notice I was not demanding much power, so less warm oil was involved with the blending on return, and oil going even slower thru the cooler makes the blend even cooler. If I run the engine harder, the return oil does warm up more on return to engine.

That would make sense but look at the data chart.
It shows oil temp at 200 in a power off decent.... that would be a low power demand situation.....
 
Scott - -

If throttle is greatly reduced in cold, very cold, weather, the temps will back back down until the therm opens up and no oil goes thru the cooler. In moderate or warm weather, it will not change as much. You have to understand all the oil goes thru the therm one direction or the other, or a blend going back to engine. Once the cooler oil is blended in, the temps will lower going back to the engine.

I would like to see you add a temporary temp sender from the tank. With the Thermostasis, I think you will see the tank temp remain fairly constant. In hot weather, it will just climb due to cooler not being able to handle it.
 
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So a comment, and a question.

I flew with the Van's winterization kit installed today for the first time. I was able to get the radiator cover plate on without removing the lower cowl. I pulled the hinge pins, and was able to flex it far enough down/forward to slide the plate into place. It was pretty warm for our recent weather, about 35 F. I used the medium oil cooler plate and the oil temp was steady at 229. On the way home after lunch I switched to the smaller plate -- took maybe 2 minutes. 213 on the way home. CHTs were between 199 and 204 the whole trip.

The question: How the heck are you seeing EGTs over 1300? What are normal EGTs in the RV-12? See photo below. I feel like I'm burning way too much gas. Those EGT and fuel flow numbers are normal for my plane.

53817178088__79630A73-6670-4C7A-A64F-074CDF07C6DB-e1516508728632.jpg
 
As a point of reference the following screens are typical for my summer flying - first two OAT 77F and last 55F.

i3w36c.png

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The carbs are configured so that the mixture is richest at or near WOT.

This is another reason that using an appropriate prop pitch that requires throttling back aways at anything other than rather high cruise altitudes (above 10K) is beneficial for performance.
 
The carbs are configured so that the mixture is richest at or near WOT.

This is another reason that using an appropriate prop pitch that requires throttling back aways at anything other than rather high cruise altitudes (above 10K) is beneficial for performance.
That's how I'm set up. The only time I see WOT is during takeoff and climb, the rest of the time I have to throttle back some. My static ground RPM is right at 5K, as I recall. Maybe a tad higher. But I'm consistently burning over 6 GPH, and my EGT rarely gets over 1220 or so. Just seems like it's running awfully rich to me.
 
A few questions...

• Are you really burning 6 GPH as measured by replenishing fuel or are you looking at fuel flow on D-180?

• Is the specific K value for you fuel flow transducer input to the D-180 in setup?

• Spark plugs look like rich burn?

• 912ULS really burns 5+ GPH at high cruise power setting. Don’t believe others reporting lower burn rate.

Fuel Consumption Chart for 912ULS
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2dabs5v.png
 
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• Are you really burning 6 GPH as measured by replenishing fuel or are you looking at fuel flow on D-180?
Yes, I'm really burning in excess of 6 GPH. Usually 6.5 or more if I'm pushing 5300 RPM. My D180 agrees with the gas pump within 1/2 gallon or so after burning 15 gallons.

• Is the specific K value for you fuel flow transducer input to the D-180 in setup?
Yep.

• Spark plugs look like rich burn?
Nope. Plugs look perfect. Exhaust pipe has black soot.

• 912ULS really burns 5+ GPH at high cruise power setting. Don’t believe others reporting lower burn rate.
Ummm... would it be indelicate of me to point out that you say that immediately after posting pictures from your own plane, showing 24.9 MAP / 5160 RPM and 4.9 GPH? <insert smiley here, mate...>

My fuel burn does seem bang on with the chart though. Where did you find that?
 
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I can usually get my fuel burn down to 4.5 GPH AT 5100 RPM and about 21?MAP, but I agree that in high cruise (>5300 RPM) 5.2 GPH is probably more accurate.
 
I installed the Van's "Winterization Kit". Oil cooler part is easy to deal with, but the radiator part is so tight that even with "Silicon Spray" all over it, it will not move up and down unless you take the cowl off. Guess I got it set to a good position the first time as the numbers are right and I haven't had to move it.

That Thermostasis is sounding real good about now.
 
Oil Therm Testing

https://youtu.be/BF_uqyqRJRg

My 205 Thermostassis element was getting tired I think. I installed a new one. Sorry about the video. Hard to fly and hold a phone etc. It is again working like it was when new. The temps on the ground were about 24F degrees ( -3C ). As you watch on climb out, you can see the oil temps increase to well over 200, then the therm closes and forces oil from the cooler to mix with oil from the therm. You can see the temp drop quickly, then stabilize. The tank oil is still warm, but the blended oil going from the Therm to the engine is lower. Hope this helps understand. The temp on the display is not the tank oil, but the blended oil going to the engine.
 
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