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Winter operations / lowest temperature for starting / preheating methods (merged)

What I still don’t get is how people manage to get away with setting up a heater, at some airfield in the open, or some hangar.

The standard health & safety yellow jacket personality type would go ballistic.

If it wasn’t for that, it would be easy to develop some sort of “oil” burning device, fan assisted so it can be a few m from the aircraft, which warms the engine up just enough (above 0C is enough) even from -30C. You can work out the energy required to raise say 200kg of ally+steel by 30C, and how much petroleum fuel would be needed. A nice exercise for the reader

Administrator
Shoreham EGKA, United Kingdom
In my experience, if the climate is calm enough ,usually one of the conditions is met- a) you keep the plane in warm hangar, b) there is power available on the apron or c) they don’t mind you using the diesel heater to warm your engine.. But my experience is limited to the northern corner of europe..
EETU, Estonia

A quick calculation:

Aluminium 0.91kJ/kgK
Iron 0.45 kJ/kgK

200kg engine made from 50kg aluminium and 150kg steel. 45.4kJ for the ally and 67.5kJ for the steel (iron actually but close enough). That is per K so for a 30K delta that is 3387kJ. Kerosene is 4300kJ per kg so you would need 0.78kg to heat up the engine.

In practice much of the heat will “go up the chimney” but you get the idea. Unless I dropped the decimal point somewhere, it takes very little. And in most scenarios much less energy will be needed.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

In practice much of the heat will “go up the chimney” but you get the idea.

Yes, and I suspect using hot air for engine heating will put a much bigger fraction of energy out the chimney than using those silicone pancake electric heaters glued directly to the engine block, and powering them from a portable generator. Incidentally, these need not be certified in any way – E-Z Heat at €200 apiece is a gold-plated option, one can get a generic one instead for a fraction of the price.

Apart from that, one more efficient way to preheat the engine is to drain the oil after flight, and preheat it on a stove to 80-100°C when pouring it back in before next flight. For a Lycoming/Continental, ~6 kg oil at 1.7 kJ/(kg·K) is about 10 kJ/K. Comparing it to Peter’s calculation, we can get about 10 K worth of engine heating by pouring in a full sump of oil that is 100 K hotter than the engine. In practice, it may be more efficient because the warm oil will directly reach the engine innards – the very parts in need of heating.

Last Edited by Ultranomad at 08 Feb 14:52
LKBU (near Prague), Czech Republic

Rather than messing with oil at say +100C (which would be lethal on spillage onto skin) how about pass the oil through a heater while it is being poured into the engine?

If the oil is heated to a (temperature controlled) +100C, calorifically the result should be the same as heating up say 10 litres to +100C and pouring it in.

OTOH heating up the oil in bulk sounds pretty good because you could do it “out of sight” and then transfer it into the engine with a little pump like the one I use for refilling the TKS fluid tank (£10 on Ebay). At about 10kg net, you would want a trolley with an insulated container.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

OTOH heating up the oil in bulk sounds pretty good because you could do it “out of sight” and then transfer it into the engine with a little pump like the one I use for refilling the TKS fluid tank (£10 on Ebay). At about 10kg net, you would want a trolley with an insulated container.

…Or, as a low-tech version, just a huge tea kettle with a locking lid. My grandmother kept one for big tea parties.

Wear gloves, insert the spout into the filling tube, and you will be safe and won’t spill anything.

LKBU (near Prague), Czech Republic

I know Im bitching but how about insisting the airport operator try a novel new way of thinking? Perhaps with their hand ever so ready to take money from you that in exchange they provide some services. A Damn electric plug is not the end of the world as far as their finances go. People in cold climates plug their cars in. Thats ok but when you have an engine worth the price of a mid priced car, ok with VAT, the price of luxury car, asking for a plug is not unreasonable. In the US as more and more people got Tanis or Rieff heaters the airports started to supply electrical power.

Peter if you go back and re read Bushes article it says preheat should be done anytime the temp goes below 0 C and 32F and is considered a cold start. “A single cold start can produce more wear than 500 hrs of normal cruise operation” The colder the worse the wear. “Starting an engine below -7 C and 20F is nothing short of a capital offense against your power plant”. I spoke to Savvy maintenance and they said it was just smart to Preheat any time the engine is in the 30s F. Once again the colder the more it should be done.

I actually preheat any time I havent flown in two weeks unless the temps are 22C and above. Having the oil circulate fasted I believe would cause less wear.

Im going to bring a long extension cord with me for this upcoming ski trip to Salzburg. Hopefully someone will take pity and move the plane close to an electric outlet.

One more thing regarding cold. I went skiing in Vt one year and the outside temp was around -20F. The planes engine was nicely preheated but the cabin wasnt. Guess what happened to all my gyro instruments? That was an expensive ski trip. Just sharing experiences.

KHTO, LHTL

I home built a heating system and spent about 80 euros on it in total for parts from my local home depot.
It can raise the cylinder head temperatures by by 15C above ambient within 1 hour and up by 26C above in about 3 hours.

When I am away from my homebase in Winter, I always try to make sure I can book a hangar for overnight parking at my destination.
The options for preheating outside are just miserably bad.

Switzerland

About €100 with readily available equipment, pretty much the same results as @By9468840 described


Temp readings at t=0

Temp at t=20 mins

Unfortunately hangar policy does not allow running of unsupervised heating devices so first I do on arrival at the field is fire up the heater, do my usual checks and let it run for probably 10 more minutes
A power switch with SIM card is working perfectly remotely controlled by texting from my phone, but as stated above, strictly forbidden. :-(

Last Edited by slowflyer at 10 Feb 13:34
EDAQ, Germany

Is there no system where instead of burning fuel with a naked flame, it could be passed over a catalyst (or anything) to release heat in some way?

A bit like the two part hand warmer devices one gets when Skiing? Any chemists out there?

United Kingdom
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