Jr.CubBuilder wrote:I just had the oportunity today to try out my propane pre-heater today for the first time. I had done some test runs outside the shop just to see if anything untoward happened, like a big fireball, but all went well.

I don't have any electricity on the ramp for my plane so the propane blower running off the car battery seemed like the way to go. It worked just fine. Tossed an old blanket over the cowl, wrapped the end around the spinner and stuffed the corners into the oil cooler duct. I probably gave it about 20 minutes of heat while I did my preflight, the temp. was in the high 20's F. That was enough to get the needle twitching on the oil temp by the time I was ready to depart. I think in the future I would do more like 30 minutes at that temp.

Let me just say that you gotta be REAL careful on pre-heats.

At 20F it ain't no big deal, but at 20, 30, or 40F below zero it is a big deal. You can blast heat into the cowl for a short period of time and get all the surface metal too hot to touch, and that oil temp will be, as you say, "twitching," but in reality all you have is hot metal 1/4 inch in from the surface, and a warmed up oil temp probe. Meanwhile your oil is sitting there in a big frozen lump, and it's not going to thaw out for another several HOURS worth of heat. Been more than one guy launch off at 30F below, only to come walking back to the ramp 30 seconds later with a seized engine.

Time is your friend with pre-heat, better is a Tannis or Tannis type heater plugged in over night with good engine covers. Or, like we used to do in the older days, drain the oil at night and bring it in with you when you go home at the end of the day's flying. Put the bucket on the heater for the night, and all ya gotta do is dump it in warm and you're set to go next morning.

And, don't forget your cabin. Want to eat a $600 gyro in just a few minutes??? Just spin it up at 40F below, and wonder why it fails on you on a whiteout day. Stick an electric heater under the dash while the engine's cooking, and drape a blanket over the glareshield to hold the heat in. Your gyros will thank you.

Gump

Jr.

Depending on the temps, 30 to 40 minutes may be plenty with a Dragon. I'd advise a couple of things, however:

1) Get a good engine cover. This will help to hold the heat you are putting into the cowling much better than an old blanket stuffed in the cowl inlets. Besides, if you fly out somewhere, and park for an hour, wouldn't it be nice to have a nice warm engine when you get back in to start again? The engine cover will assure that.

2) As the man says, EVEN heat is the key. Let it heat soak. Put the engine cover on it, heat it for 20 to 30 minutes at that temp, then button it up, and let it soak for 15-20 minutes. If it's -20, a Dragon will take at least 40 minutes, plus a heat soaking period.

3) ALWAYS watch any combustion heater. Do not be tempted to go get something out of the car and be gone for five minutes while heating.

4) I like to see the oil temp guage well off the peg at start, no matter how cold it is out, not just twitching.

Again, heat soaking the engine is the key. You want the whole engine about the same temp, including that very expensive piece of metal--the crankshaft. Which is surrounded by bearings, by the way, if you get my drift. It's in the middle.

A Dragon works fine. Just take your time. At +20, fifteen or 20 minutes of heat, followed by a heat soaking of 15 minutes with a good engine cover will be more than enough. You have to play it by ear.

Warmer is better, though.

MTV

Been using the red devel for 6 years now. Anything below 40 deg I heat. I am a plumber and anytime it is below 20 I am out thawing pipes which is more important than flying cuz it pays for the flying.

Did not think of the soaking but if make good sence. I thaw pipes with a welder. Probably not a good idea to hook up the leads at each end of the crank to heat it up.

Tim

You may want to invest in a quality cover, I retired my Red Dragon a few years ago. Now I use a Honda EU1000 and a oil pan heater. A good cover will make all the difference in the world when doing a pre-heat. I was using an old sleeping bag before I bought my Kennon cover and was surprised at what a huge difference it made.

Seems to me that if you're without power a generator with an electric oil pan heater and cylinder head heaters is a much better way to go than a combustion heater. You can bundle the engine and prop up, put a couple hours worth of gas in the generator and go do something else for a couple hours. When you come back your engine is tosty warm and there is essentially no fire danger so long as the generator is placed away from the airplane. You can put a small ceramic space heater in the cabin while you're at it.

I have the Reiff cylinder head / oil sump heater on my 140 and it works really well. Of course I don't need it here in California, but the last owner lived in Wisconsin. The cylinder head heaters only add .94 lbs and can be owner-installed in a hour or so.

A side note...it's important to wrap the prop in insulation, otherwise it acts as a giant heat sink for the engine.

up here in alaska its always a pre-heat day . what works for me is cutting a u shape on the end of the stove pipe from the red dragon that mimics the shape of my oil sump.By heating the oil it seems to radiate alot mor heat. 20 min is the norm. the red dragon is a godsend for thawing wings also, pop 2 inspection covers and hold the scat hose back a foot or so and in 10 min a wing thawed and dry

Be careful that you don't let the mouth of the scat tubing point directly at a painted surface for too long or your paint will start to bubble and any fiberglass parts (Maule cowls) will become soft. Speaking from experience on that one. As MTV stated: ALWAYS watch any combustion heater. Do not be tempted to go get something out of the car and be gone for five minutes while heating.

-Low

OH, and be reaaaally careful pointing a propane combustion heater discharge inside a wing. Propane contains HUGE amounts of moisture. If you point that thing into an open inspection cover, even from some distance, you may remove the frost from wings, but you also just pumped a LOT of moisture inside your wings. That is not good in my opinion, for the longevity of the wings.

The only problems with using a generator is four fold:

1) they take a while to be effective, as in a couple hours. There is a temptation to get in a hurry. Don't. If you've got something else to do (like go get breakfast) good--just don't sit there gnashing your teeth, then cut the pre-heat short.

2) While you are having breakfast, some scum ball may come by and "adopt" your brand new mega buck generator.

3) I have a Honda 1000 watt generator. It takes a good two hours to get even close to warm enough it it's below zero with a Reiff system. That generator will not run BOTH a Reiff system and a small fan forced heater. It's one or the other. A 2000 watt Honda would do this just fine, but more $$$$. I like the 1000 watt model.

4) None of the little generators I've used, including this Honda, will start if they are cold soaked. When I say cold soaked, I'm talking -10 or so, maybe warmer. So, if you plan to use this technique out in the woods, take your generator to bed with you.

Again, take your time. The Dragon works just fine, and it's a LOT cheaper than a generator, unless you already own a generator and the engine pre heater.

Just use the combustion devices intelligently.

MTV

MTV brings up some very good points.

I use the generator a bit different than most. I have it chained to the gear leg, and start it up the night before when parked outside. The thing runs about seven hours and the engine is always warm in the morning. When I arrive I gas it up and run a little cabin heater while doing the preflight an any last minute duties. I don't mind cutting the cabin heat short but never the engine.

I used to use a generator and space heater, I made a splitter out of a coffee can and a couple of soup cans and would put one heat hose under the cowling and one into the cockpit. I would then sit in the truck and watch everything. The engine was warm when the crank would turn free, like has been said you can get the outside of the engine so hot it will burn you and not have any heat into the center of the engine.

In the hanger (no heat, no door) I use a little quartz heater pointed in a safe area and an engine cover.

Shane

I know this is an old post but the subject is relevant each and every year so the subject doesnt really get old.

One part of this discussion that doesn't show up here is portability. In order of preference based upon what is available to me, I like a full Tanis system. I say full because there are parts of the system that do a portion under the hood but not all of it. The complete system is safe and thorough. It can be used overnight safely, or more safely than most. In today's world, if you have really good access, some of these circuits can be turned on remotely with a phone. Running the heater all night isn't necessary but being able to turn it on four hours prior to the intended flight is great. The second level would be the stand-alone propane heater. I use a Red Dragon. This requires all the precautions mentioned above. This lives in my truck. I've used it to thaw my diesel fuel system in the middle of nowhere in AK when it got really cold. It is very effective and isn't isolated to heating airplanes. Lots of heat and lots of airflow. Airflow, by the way, is key. The hot air needs a place to escape so it's circulating. Leave one inlet near the spinner open so the now cool air can flow out. That way you're not trying to force air into a closed chamber. The last method for me is a Northern Companion type heater. It's light and small, and portable for backcountry use, which is important in the cub. It is effective, but less heat and less airflow. This will take a longer time. I also use it after I've heated the engine compartment/prop combo to heat under the panel while the engine heat soaks. One of the most important components of an effective preheat is the engine blanket. A good one does two things: It holds heat in (useful for making the preheat efficient, and once landed but planning on taking off again, it holds that hard-earned heat in), and it acts as an emergency blanket if forced down. Mine is a Wiggy's design, twenty-five years old, and is international orange. I have modified it with an opening in the cowl to let air out. As part of my engine blanket "system" are prop blade covers and spinner cover. As said above, the blades are a heat sink and dissipate heat quickly. That means that while the rest of the engine is warm and toasty, the bearings at the front may not be. This is a bigger deal on the bigger engines and big multi-blade props. Lastly, I hate to drain oil and refill, but its been used for eons and works. Having a quick-drain is essential to being able to do this and having a container to drain hot oil into and be able to put on a stove is another required piece of equipment to be carried and its messy (no way to avoid that part). Good luck, and happy flying during one of the most beautiful seasons to do so.

Another interesting option when away from home. 18V Lithium Battery / Propane forced air heater. Just need some flexible ducting.

https://www.ryobitools.com/power-tools/products/details/18v-one-plus-hybrid-forced-air-propane-heater

Draining oil always seems to come up in these discussions. But hardly ever if ever used today.

Back in the day, most bush planes were equipped with radial engines. And radial engines, by necessity, are dry sump engines. All the oil resides in a tank, rather than in a sump at the bottom of the engine. That oil tank is typically located aft of the engine. The Beaver, for example, has the oil tank located in the cockpit, between the pilot and copilot’s knees.

And, most of those engines carried a lot of oil (6.4 gallons for an R-985 if I recall).

Where I’m going with this is that the pilots in those days drained the oil and put it behind the stove in the roadhouse overnight to keep it warm. In the morning, they fired up a fire pot, and put it under the engine, with a tarp over the engine extending to the ground to trap that heat.

When the engine was warm, they’d fetch the oil and put it in the tank, fire up the engine and go flying.

The reason they drained the oil though was largely because there was no way to get heat from a fire pot safely to that oil tank. So the only way to get the oil warm was to drain it and heat it separately from the engine.

Since the vast majority of engines in use today have wet sumps, preheating the oil with it in the engine makes a lot more sense than draining the oil.

I worked airplanes north of 66 for twenty winters and never saw anyone draining the oil to take it inside at night. But I’ve seen some pretty innovative pre heat systems.

MTV

The Ryobi unit looks appealing. I am having a lot of problems locating a red dragon and might have to try that as an alternative.

Narwhal747 wrote:The Ryobi unit looks appealing. I am having a lot of problems locating a red dragon and might have to try that as an alternative.

There has to be a lot of Red Dragons laying around in AK. But that Ryobi unit might be a better design in any case.

MTV

Just a side note on the Ryobi unit that takes those 1 lb. cylinders. Granted, I am not located in the interior of Alaska, but in northern MN.It can get VERY cold here. Most all of the gear that I have used with those 1 lb. cylinders have issues when it gets very cold. They spit, sputter, or just palon quit from freezing up. If they have some way to mitigate some of the heat to the cylinder, thy work fine. But anything with those cylinders exposed to the surrounding air seems to cause them to freeze up. The Little Buddy heaters don't seem to be as suseptible to this but the sunflower type heaters and others all have this issue.

I think the Ryobi might be great for a day out ice fishing but for a full on pre-heat from a cold soak condition it may fall short

GumpAir wrote: Your gyros will thank you.

What are these old things called "gyros?"

What are these old things called "gyros?"

Another solid reason for either an AV-30 or G5

I would try to avoid anything that takes batteries to run. Once the battery is dead the unit is useless.
DENNY