Pre-Heat

[onex0036]

Heavens, much too complicated. Get a small stick on block heater, they're made of red silicone and go on with a special adhesive. Use the area on the right forward lower block area. Heats up in no time and the cord can be neatly coiled up inside the cowl and accessible at the lower outlet. No prep required as indicated by all of you. Available from any automotive supply house. Got mine from our Canadian Tire Corporation store!

Pierre Marcotte
Onex 0036, Aerovee
Cornwall, Ontario, Canada

[jgpainter2]

Hi Mike. This is what I do to preheat my Sonex/Aerovee. Go to the Wolverine engine heater website, and note model 9.0,125 Watt round 3" heater. This unit sells for $60. Then, realize that VW made a sump plate WITHOUT a drain plug for their later (1970's ish) engines. This was to force lazy mechanics to clean the strainer when doing an oil change, as the whole plate had to be removed. True story. The Wolverine heater attaches PERFECTLY to this sump plate without modification. It glues on and has a 6' power cord which I ran up to the fuel access door. Then, also from Wolverine, I bought their automatic power cube, which plugs into any outlet, and provides power when the temps are down around freezing. It does not allow power flow at warmer temps. My plane is kept in an unheated hangar in Heber, Utah, and the temps routinely drop below freezing. The heater works so well, that I elected to incorporate a rheostat and keep it set at about 50% power. This usually finds my oil temp in the 60's and cyl head temps about the same. Convection and conduction both come into play here. I cover the cowl with a thick quilt, and block the cowl inlet openings to trap the heat. works perfectly and is CHEAP ! Good luck. George. N1020X.

[mike.smith]

Hi Mike. This is what I do to preheat my Sonex/Aerovee. Go to the Wolverine engine heater website, and note model 9.0,125 Watt round 3" heater. This unit sells for $60. Then, realize that VW made a sump plate WITHOUT a drain plug for their later (1970's ish) engines. This was to force lazy mechanics to clean the strainer when doing an oil change, as the whole plate had to be removed. True story.

Except I have a drain plug and an oil temp sensor in my Sonex machined sump plate, so that particular product won't work. Now if they had a donut shaped heater...

[mike.smith]

OK. This is experimental aviation, and now that I have these heating pads, even if there is another solution, I'd like to find a way to make these work:

http://www.amazon.com/gp/product/B007PA ... UTF8&psc=1

I have tried using a simple rheostat, and also a 600 watt wall dimmer switch:
http://www.amazon.com/gp/product/B00JJC ... UTF8&psc=1

I thought they would regulate the flow of electricity and therefore the temperature. But they don't. As far as I know these pads are just simple resistance heaters (long loops of wire heated by the electrical current). No matter where I set the rheostat, the electricity is either full-on or full-off. I can move the dimmer anywhere above "off" (5%, 25%, 50%, 90%, etc), and the pad always goes up to full temp, around 350+ degrees.

You can tell I'm no electrical engineer (it's a minor miracle I was able to successfully design my Sonex electrical system). So if there ARE some electrical engineers out there, I'm wondering if you might have some ideas.

Again, I know I might be able to use some other product (hair dryer and other blown-air solutions don't work for outdoor, overnight use), but I need a "project" anyway, and I don't like getting beat by an inanimate object! :-)

[dtwolcott]

Mike
Rather than a rheostat to limit the voltage I think you need a thermostat that measures the temperature at some point on the engine that turns the heater on and off based on a set temperature.

Don
Waiex 132

[mfazio]

Mike,

Do you really need to throttle the output of the heating element? I'm no expert, but would think you want the final temperature of the engine as close to operating temperature when you are preheating. Running the engine up to that temperature is probably the ideal but hardly necessary. Would it be easier to put the element on a timer and run it at full heat for a period of time to get to your target temperature? From what I have read there are issues with condensation in the engine if you keep the engine on preheat for extended periods of time. I'm curious about what temperature others keep their heated hangars at to keep the avionics and engine at reasonable temperatures. I have heard some with heated hangars also preheat the oil before flight as well.

I have yet to find hard rules on when to preheat and to what temperature. Cessna, for an older model 172, just says to preheat the Continental when above freezing and that is about all the guidance they provide. Don't know if recent models have more advice.

I haven't built an Aerovee (yet!) but have not seen any guidance from Sonex as to when to preheat, how to preheat and to what target temperature? In an Aerovee do you have really tight tolerances on the crankshaft bearings as you would find on a production aircraft engine? There is the dissimilar materials issue to consider in an Aerovee but on an automotive VW I'm sure there is pretty of slop to allow oil to the bearings to allow you to start in in cold temps without detrimental effects.

Mike Fazio
Waiex #63( still building)

[mike.smith]

Regarding the questions about throttling the heat or using a thermostat: 350+ degrees is WAY too hot for simply preheating. Once the block warmed up to temp the oil would eventually end up at a similar temperature. There isn't much metal between the heater and the oil, at the oil sump plate. And the pads heat up to that temp in about 15 seconds, so a t-stat would be going on and off a LOT. And finally, when I DID put one of these under the oil pan, and it heated to 350+, any residual oil on the face of the engine began to SMOKE! That took about 30 seconds to happen. I don't like smoke.

Here is what Jim Weir said (he writes the AeroLectrics column in Kitplanes).

First the answer to your heating pad question ... you are correct that all that is inside is a simple resistive heating element. HOWEVER, I note that the operating temperature of the pad (as listed in the ad) is 450 dF. My Lord, man, that’s enough to strip paint. Or solder. Or remove flesh from bone. The wire inside is SO heavy and SO short that your poor old dimmer doesn’t stand a chance of being able to go low enough to control the temperature.

May I suggest that you return the pad(s) if possible and go down to Walgreens (or your favorite pill store) and get a regular old medical heating pad or three. Those will only go up to a hundred and twenty degrees or so, and that ought to be WELL enough to keep your engine warm. Hook them to the UNDERside of your engine ... heat being a rising phenomenon. Cover them with a blanket (thermal if you can find one) to keep the hotsies inside the mechanisms.

Second, that little thyristor control box is an unknown quantity. May I further suggest that you run yourself down to your local Home Depot (or whatever handyman store you like) and get a heavy duty light dimmer, metal box, plain old socket, and AC cord with bare wire connections (or a cheap extension cord and cut off the end). Wire it up like a plain old lamp dimmer and that ought to be more than enough for a heating pad or two. Just look at the wattage on the pad(s) and don’t connect more than the dimmer is rated for.

So I need to look for another solution. There are options available in different sizes, but none are really geared toward the limited real estate of the VW oil sump plate, with 2 fittings sticking out. All those electric options require 100% bonding of every square millimeter of the pad to the oil sump. Not even stamped serial numbers can be tolerated, according to all of the manufacturer's instructions.

The heating pads that Jim refers to are way too big to fit in the tiny cavity between the oil sump plate and the bottom-mounted oil cooler that I have. I had previously thought of that. Unless anyone knows of some really small heating pads (like 8" long and 3" wide).

[Bryan Cotton]

I have put these on two generators:
http://www.amazon.com/gp/aw/d/B000CSW2S ... SX200_QL40
Works great, but not low budget. Has a thermal sensor and runs off 220. The pad is for the battery and the other part for the oil.

[kmacht]

If you want to go the experimental route how about moving your oil temp sender and putting a frost plug block heater in its place. You would probably have to drill and tap the sump plate cover for a larger thread but as long as you didn't buy one that was too tall it should clear the screen.

http://www.amazon.com/Kats-11412-Watt-F ... 70&sr=1-38



Keith
#554

[DCASonex]

There is a second reason to use a heater, and that is to keep engine just slightly warmer than air around it to prevent condensation and corrosion. A constant low heat will do that better than an on-off control.
David A.

Mike
Rather than a rheostat to limit the voltage I think you need a thermostat that measures the temperature at some point on the engine that turns the heater on and off based on a set temperature.

Don
Waiex 132