Winter preheat

[jmvolpp]

Here comes winter and the necessity of preheating our contrary-when-cold A-65s. As my hangar is without electricity, I'm in the process of engineering a manifold for a dual burner propane heater (sits on top of 20# tank), the plan being to attach an aluminum dryer vent hose for each air inlet or side of the cowl. Depending on the heater throttle setting (L,M,H), I think it puts out up to 15,000 BTU. But one of the past forum posts suggests using the Coleman SportCat catalytic heater, rated at 1500 BTU, placed directly inside the cowl. Physically, it appears it would fit in the left side, and I'm assuming it won't hurt if it's not perfectly vertical when running, but isn't that quite a fire hazard? And if safe, is its output sufficient to heat the engine in a reasonable period of time?

Mike Volpp
N44305

[hangarb7]

Re: Winter preheat

Hi Mike,

I'm lucky enough to have electricity in my hangar so it takes about 45 minutes for my Pelonis ceramic heater to heat my engine to an all over warm condition to the touch of the engine case. This heater is 5200btu's and assumes starting at 30 degrees F. Colder takes longer, and occasionally I take a 1500 watt hair dryer and blow air into each exhaust pipe (I have two pipes as I have a dual exhaust).

I put the flex hose into the bottom back of the cowling, put a heavy blanket on top, draped over the sides of the cowl, and by the time I do my preflight chores and pump the tires, etc, the motor kicks on the first flip.

I made a simple cardboard cover for the front of the heater and cut a 4" hole in the front for the flex hose, winding it in like a screw to hold it in place. Squash the other end of the hose to slip into the cowl. You can feel the warm air coming out thru the front of the nose bowl.

But let's be reasonable. I remember this comment that someone made about putting a heater inside the cowling. With how rapid these old birds burn after ignited (I doubt you would put it out in time to save anything), does it make any sense at all to do that? It might burn the hangar down, too.

Keep the heat source away from the gas fumes is what I say.

Jack D.
'46 BC12D

PS I also air out the hangar by opening the door before I start just in case there are any latent fumes from fuel, paint, acetylene tanks, etc.

[mhorowit]

Re: Winter preheat

There have been some interesting discussion on pre-heating on this forum. Of particular interest was the discussion of just what it is one is attempting to accomplish. Something about the need to warm bearings(?) ; anyway, the heat of the case wasn't a good indicator of adequate pre-heating. - Mike

[hangarb7]

Re: Winter preheat

Something about the need to warm bearings(?) ; anyway, the heat of the case wasn't a good indicator of adequate pre-heating. - Mike

Hi Mike,

And I agree with that. However, I do not have any real method for determining the internal temperature and figure that if the outside of that big chunk of metal gets warm, that inside it is probably better than super cold. the previous owner of my airplane kept this bird in an open front T hangar, and never preheated in the 12 years he owned the airplane.

I'm not saying that is correct, but what I'm doing is far better than a lot of people do with their airplanes. My airplane has approximately 1700 hours on the original engine from 1946 and runs very sweet.

By the way, I never got an indication this past weekend of temps in the green until I was flying for ten minutes, and I let her warm up idling for about fifteen.

I figure I'm giving it the old college try

Jack D.

[barnstmr]

Re: Winter preheat

My airplane has approximately 1700 hours on the original engine from 1946 and runs very sweet.

Surely you don't mean that your engine has never been overhauled since new???? It isn't uncommon to see an engine make it to TBO, but to make it 50+ years in doing so is quite uncommon.

[Len Petterson]

Re: Winter preheat

1745 hr TT Airframe and engine.
oilpressure 35 psi hot.
but new mags!
Len

[Peter Collin]

Re: Winter preheat

I have an engine cover for my 150 that I keep in a unheated hangar for the winter. I just use drop light in the engine compartment (75 watts). I plug it in the day before and I see 40 degrees on the CHT the next day. I would think after 12 + hours the engine has reached the same temperature throughout, the temperature doesn't drop noticable after you take the light out.

Peter

[matsuthunder200]

Re: Winter preheat

Mike
I was just wondering how cold dose it get where you are. do you have a engine cover so that when you do preheat it holds in the heat?.
Here in alaska i have seen about every kind of pre heater there is .
Without elect, we are limited on what we can use for pre heating.
I use a single burner colman stove that burns avgas or regular unleded fuel.
I put the stove in a 5 gallon can that i made a door for... and have a 4 inch stack and use dryer duct to run from the can to the bottom of the oil pan.
the thing you haft to do for this to work is to cut 2 inch holes all the way around the can nere the bottom. This dose two things it keeps the stove from getting hot and it makes a draft so the heat gose thrue the dryer duct.
I have had this pre heater for about 15 years and i take it with me when ever i go on a trip where i spend the night. It takes one hour down to 0 deg
at -20 about 1and a half hours.
I added a picture of my bubble type insulater for the inside of the cabin it works great for winter flying it make it so there is just the cabin to heat up..

[hangarb7]

Re: Winter preheat

Surely you don't mean that your engine has never been overhauled since new???? It isn't uncommon to see an engine make it to TBO, but to make it 50+ years in doing so is quite uncommon.

Terry,

I am at work so I don't have my logs in front of me for the TT, but it is close to Len's at about 1745. I have the logs back to 1949. One cylinder had a valve job of some kind, I think in the '70s, and of course, mags replaced with Slicks and shielded wires and plugs. Carb was overhauled in the early '90s.

Starts almost always on the first blade and hauls me and a friend around pretty good. Certainly blows oil out the pipe, but since I've owned it almost five years, has passed compression cold every time easily.

I do feel blessed.

Jack D.

[flybikefarm]

Re: Winter preheat

I see two reasons to preheat. First the cylinders are steel as is the crank, the case is aluminun. These metals have quite a different rate of exspantion. Secoundly if the the oil is cold it is difficult for the pump to suck it from the tank. Many of these older engines have marginal oil pumps anyway, according to the complains about low oil presure at idle do to excess wear in the pump housing. I run all diesel equipment on my farm and the rule of thumb is if when you check the oil and it takes longer than 4 secounds for a drop of oil to fall from the dip stick, you either need to preheat or change to thinner oil. George

[Harbi]

Re: Winter preheat

Mike,

I have use a preheater like the one Lance has pictured. I use a Coleman single burner dual fuel stove. The one I have fits great in a metal coffee can. I drilled some 1/2" holes around the can below the burner about every two inches. I then cut a square hole for the burner control and drilled a larger hole for the primer pump. A 6" to 4" stove pipe reducer fits perfect on top of the coffee can. I used a small 4" stub pipe out of that (8"piece). I too used the 4'' alum. dryer vent. There is a company that sells an approved version like this. I think they use a MSR stove. I think the company name is Northern Companion preheater.

Wade Harbison
Tok, Alaska

[Forrest Barber]

Re: Winter preheat

All pre-heat is good, and remember the old trick of draining the oil, taking it home and bringing it back out heated and pouring her back in again after any pre-heat that you can devise. WE had a guy use his car heater with a plate over a window with a large flex hose to the cowling.

[N95179]

Re: Winter preheat

I use the Northern Companion heater when I'm not near an outlet. It uses an MSR camp stove like mentioned above, it's very compact and light weight. Doesn't take too long to heat it up for being so compact. It's great for the survival pack too...cooked some venison on Montague Island with it once.

[Len Petterson]

Re: Winter preheat

In the low lands of Ontario we dont NEED to go flying as we fly for fun but it is nice to know you can do it.
Alaska and and nothern Canada has weather what says 'you shall', or ----
The stove mention is made to run on cargas so it does not need naphta gas the clear stuff, correct.
We can acctualy have use for one ,not only for the aircraft.
thank's for the hint.
Len

[Norm G]

Re: Winter preheat

I put together a pre heater using a trailer/ motor home furnace that measures about 14X14. It easy to set it up and it was cheap. I got mine out of a 40ft junk trailer for free. The thing workes on 12volt or 110AC. Tie in your gas grill propane a couple of dryer vent hoses and your ready to go. A decent aircraft or car battery will run the heater and blower long enough to heat the engine on the coldest days.

Norm