Thermostat or radiator shutters

[cap01]

after a couple of years of flying in a cold cockpit I finally tried the duct tape on the radiator and finally some heat . Now for a more permanent fix , thermostat or shutters . Not too sure about a thermostat without some kind of bypass but also not sure of how affective shutters would be on the back side of the radiator . Maybe some of the guys up in the real cold country would have some thoughts on this ? Thanks

[jamesmil]

we used a in line thermostate from" highwing llc" it works well summer or winter. we can have some 95' days in the summer and the temps are fine.
on those real cold days around 40';) the water temp is around 190'

[Dorsal]

Two concerns I have about the inline thermostats is;

- Restricting flow and increased pressure. They are certainly used in other Rotax applications so perhaps not an issue though some models use a by-pass.
- Restricting flow to the cabin heater as I think the heater T is down stream from the likely location of the thermostat. This might keep the coolant temps up but not provide more cabin heat.

For these reasons I went with AL tape on half the radiator, seems to work OK but I liked the idea of the coolant thermostat better. I use a thermostat on the oil and it works great. If others know why my concerns above are silly please chime in :)

[Dave S]

I theory, like the idea of a coolant thermostat, primarily for the sake of maintaining a constant healthy temperature for the engine.

In practice, I have not installed one simply out of wanting to keep the system as simple as possible.

I.C. (internal Combustion) engines operate most efficiently with as high an operating temperature as the materials the engine is made of and the oil will tolerate. An inline thermostat serves that purpose; and, provides the side benefit of a more effective heater. (same idea with oil thermostats...keep the temp up to a decent operating level)

My first concern with any kind of liquid or air restriction device like a thermostat or radiator shutter in my airplane is failure mode operation. A liquid thermostat has two failure modes...stuck open or stuck shut...(or something in between). The first is not an operational problem; however, stuck shut means the engine has to be shut down in time to prevent damage or it will shut itself down due to overheating...either way...no power. Having said that, I can't say how common that kind of a failure is with Rotax in line thermostats...I know I have had stuck shut thermostats in cars and you are all done pretty quick.

I have thought about a shutter designed so failure mode would blow the vanes open....although, control systems on certified aircraft (throttle, ICO, Carb Heat, cowl flaps) have no fail safe mode...they count entirely on the system not failing...so maybe failure mode concerns are over-rated.

I am pretty cautious about things like this.....my luck is best explained in terms of a contest I was in once....with 200 door prizes......There were 201 entrants including myself.....and I don't need to even say who didn't get a door prize.......:mad:.

I am leaning towards some kind of shutter system on the back side of the radiator as a more fool proof system; but, the fact that all is running well and the cabin is comfortable....oh well.

Dave S
KF7 Trigear
912ULS Warp Drive

[HighWing]

There is one other option for you guys with the in cowl radiator fed by the NACA duct. The 5 Outback with Series 7 FWF, I helped finish, has a "Door" on the NACA Duct opening that consists of the cowl skin cut along the curved sides and aft but with the short forward edge uncut to act as a hinge. A fiberglass "joggle" provides a seat for the door. and foam stiffeners were bonded to the door for rigidity. To avoid having to unhook the control cable when removing the cowl, we designed a mechanism that reversed the pull on the cable at the cowl firewall interface to a push motion. Fail safe was a spring set-up that would open the door in the case of cable failure. Pulling on the cable in the cockpit pushed the door closed through the nesting push fittings. Three photos attached.
Lowell

[farmboy]

I had my first flight today after installing a oil Thermostat,oil temp held at 158 degrees outside temp was 11 degrees farenheit. Before installation I was running 128 degrees.

Do I understand this correct that the 912 needs a bypass inline when a coolant thermostat is installed? I have a cabin heater so I want full heat and do not want too much pressure in system when thermostat is closed. Sorry if this has been discussed before but just want to do things right. Thanks for the help!

Series VI 912s

[HighWing]

A quick note on the HighWing LLC inline thermostat.

The thermostat was designed after a similar thermostat that was shown at some of the European airshows several years ago.

There is an internal bleed or vent just like in your Porsche or Corvette.

The system pressure is determined by coolant temps and the pressure cap on the Spider Tank.

They have been in use for four years.

Any feedback has been similar to jamesmil's

I have one on my new Model IV and since most of my hours have been in Phase One, constant monitoring shows very consistent temp rises - much quicker than bare naked - then holds the minimum during flight.

Respectfully,
Lowell

[cap01]

lowell , what thermostat do they use and what temp do they regulate to ?

[cap01]

farmboy , dont you think thats still a little cool for oil temp ? i also have the thermostat in the oil system but also have to cover the oil cooler in in the winter . i run the temp 190-200 f . the radiator cover is a slide arrangement with holes so i can vary the amount of air passing thru the cooler , ground adjustable . we dont normally get outside air temps in the as cold as you do in the winter either .

[wannafly]

I use a oil thermostat from Bullyhawk. It keeps the oil at 200 degrees and definitly helps warm the engine faster. In the real cool weather 32 F or 0 C...I still put duck tape over the oil cooler just to help out. At those low temps the oil will only reach up to 180. I do not have a water thermostat. I also put duck tape on the water radiator. If you look close at the photo you can see the tape. I leave two cooling veins open on both rads. So yesterday I went up it was -5 C or 28F and the oil was at 205 and the head temp was 210.
Question...I do NOT have a heated hanger or pre engine heat. Before start up I hand prop about 50 blades, then crank without mags on for 3 or 4 seconds(I now have indicated oil presure). Turn on mags, fuel pump, pull choke and it fires almost immediately.
With the oil this cold will this method hurt my engine?:eek:
I have 70 psi presure before it starts. I have head temp in about 4 minutes and my gauge starts at 120 degrees. The oil temp moves the gauge in 7 minutes also at 120 degrees. This is at a 2000 rpm idle.
Your thoughts....?

[kmach]

I am a believer in preheating an engine when it is below freezing. pour oil out of an oil can sitting outside below freezing and one that is at room temp, there is a big difference in flow.

the metals of the engine itself will have tighter ,closer tolerances by the low temps .

I use a reiff 150 watt preheat system , at -15 C / 5 F it takes 4 hrs plugged in to get these pre-start temps: 67F CHT's ,57 F EGT's, oil 63 F, coolant 44 F .

I usually plug it in to a timer and give it a minimum 5-6 hrs of preheat before planned flight, temps are usually in the 80's F before prestart.

unheated hangar, cowl cover, reiff preheat 150 watt are the conditions.

[HighWing]

what thermostat do they use and what temp do they regulate to ?
The thermostat is set at 180°. I don't know the specific part number, but it is available locally possibly as special order as it is smaller diameter than those you will find in your cars. The internal bleed is modified on the side of caution.
Lowell

[Av8r3400]

Lowell - You will hear from me shortly for an order on this, but do you know what application the thermostat is - in other words, what type of car does it fit?

[HighWing]

Larry,
I don't know the part number or application. I talked to Mark yesterday and he will email that info -
I do know that the diameter is smaller in diameter than the typical auto thermostat to reflect our one inch lines. He mentioned that some parts houses keep them in stock.
Lowell

[cap01]

lowell, with the 180degree thermostat , is that what you indicate for cht/water temp?

[HighWing]

Chuck,
In the winter, that is what the minimum temp gauge will indicate.
Lowell

[Eric]

Hello

On a car engine the thermostat opens a bypass line so that there is a way that the pump can circulate the coolant through the engine and the heater.
I have an old NSU Ro 80 and with te old system without bypass the engine had a lot of cooling problems.

For oil and water thermostats look at Silent Hektik ,the have them and there are some drawings with dimensions.

Eric

[SWeidemann]

Folks with Coolant Thermostats,

I'm in assembly mode on my Vixen with Rotax 912ULS and would like to know where in the cooling system does the In-Line Thermostat go? (A Highwing product I believe).

It can go "after" the spider on the coolant's way to the radiator or just "before" the water pump. (If I mount it before the water pump
I can use the coolant cabin heater hoses for a bypass).

Any and all experiences or opinions will be much appreciated.

Skot

[Slyfox]

these poor little airplanes are bad in the winter time. air leaks!!!. I have my redneck ways when it comes to this little plane. I use heated air off the radiator. yup, a plastic oil funnel and scat tube into the airplane from outside. it does work pretty good down to 25 degrees f. after that , too cold. I also use a heated vest plugged into the battery. and thin gloves. If I had a thermostat this wouldn't work. I use a piece of aluminum with a couple after market ties for installing an air cooler on a car and stick it on and cover up the radiator. works like a charm. no weight, I'm very weight conscience. I love the performance of my plane. so no more weight than I need. I do have the oil thermostat way cool. and have the reise system for both the block and the oil tank. I leave mine on 24/7. I jump in the plane start and run to the runway and take off. about 5 minutes wasted.

one more thing, I remove the cowls and put a plastic wrap around the windshield bottom and around the firewall back to the door. this really helps out.:D

[kmach]

Hi,
I dont think before the water pump is a good idea, the thermostat restricts flow at times which i think would be very hard on the water pump.

I have my thermobob thermostat about 8" above the radiator "IN" , after the expansion tank.

No room on my setup to have it closer to the expansion tank on my setup.

[Paul Z]

I purchased an oil thermostat from John McBean, easy to install, and works great. Mounts behind the engine to the engine mount. It never fully restricts the flow of oil. This is the same one used on the rest of the SLSAs.

[HighWing]

Mine is mounted like Kevin's My outlet to the heater is just down stream from the thermostat. If I felt I needed the external bypass, it could be mounted between the inlet and outlet of the heater. As a note, HighWing LLC is no longer in business, but the thermostats are still available through my partner's new business. In keeping with the guidelines of the forum and not being an advertiser, send me an email - preferably - or a PM and I will provide the contact information.