Tiedown engine pre-heat

You need a apu with cell phone activated start. This would be the perfect application for Honda to make a Efi electric start Honda 1000, tied into the fuel system with one of those exhausts kits on eBay the routes the exhaust and cooling air out the back of the aircraft. It could purr away in the baggage compartment.

Will it ever happen? NO!

Get to know the FBo give them some good tips and maybe they would let you leave a Honda 1000 with them and for 10 bucks a time maybe they would toss it in the cart run over and plug in your plane for you.


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Mtns2Skies said:
I intentionally didn't clarify because I was curious about all cases. What about when in the deep bush? What about at a large airport when transient? What about at a home base with no FBO but still tied down?

This too was prompted by Ted's engine maintenance guide but more of a how do I then protect my engine (thermally) If I don't have access to electricity?

Now wrong answers here :)
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Unfortunately, here at POA you find that sometimes the best thing is to just PM the guy who really does know about this stuff.
 
Fearless Tower said:
Honest question: what is your airplane and your life worth? Ted has a good point about problems with red dragon preheating.

I always looked at it (making a separate trip out to the airport to plug in the preheaters) as a small price to pay.
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To be fair, the specific situation on the 310 was also a real corner case. It was so bitterly cold that night that you couldn't turn the props by hand prior to use of the Red Dragon. That was the point where it was cold enough that a single start could cause a catastrophic failure, which it did.

A more typical case is one of those where you get extra wear from a cold start on an engine that wasn't properly pre-heated. And, to reword a famous quote, "If you don't preheat your engine on that plane, you'll regret it. Maybe not today, maybe not tomorrow. But soon, and for the rest of your engine's significantly shortened life. Or worse, YOUR significantly shortened life." Unlike a car, you won't hear a rod knock in an airplane... until the rod comes out of the crankcase. You'll hear that.

Fearless Tower said:
Unfortunately, here at POA you find that sometimes the best thing is to just PM the guy who really does know about this stuff.
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I wonder where one could find such an individual... :idea:
 
operation of a Red Dragon Pre-heater ...

Unfortunately it's not fool proof. but if you are smart enough to fly an aircraft, you should be able to follow the instructions. But unfortunately we have pilots who should not be playing with fire.
 
GMascelli said:
Ughhh..... I remember the days of rolling out 300' of extension cords. It sucked!! I had a small generator that worked but always thought it would 'walk' during the night so I stayed with running the extensions.
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A simple bicycle cable and padlock will secure your generator to your airplane. The trick with using a generator is to have a heater that works in a predictable amount of time. My first Reiff system was the original standard system and it was anemic. Mr. Reiff sent me the higher output Turbo XP bands and that solved my problem. In temps around 10* I run my generator for about two hours for adequate preheat. Three hours is better. I always use an insulated engine cover and usually use prop and spinner covers. My new EX Cub isn't even covered yet and it already has a new Turbo XP heat system installed.

For me a 50 or 75 watt sump pad and a Little Buddy warm air blower was the second best heat solution. It took at least twice as long as the Reiff and sometimes three times as long if the wind was blowing. Not as efficient with a portable generator as the Reiff. A sump pad alone isn't adequate in Alaskan temperatures unless you have at least 12 hours and fairly warm winter temps. And no wind. Sump pads alone on a cold day are a great way to frost plugs and make you do a much more thorough preheat. With short days that's not a good plan.

Red Dragons take way too long to heat oil. Guys are impatient and usually apply too much heat for too little time. Shock heating, anyone? You've probably talked about shock cooling. Which is worse? My own poor opinion of a Red Dragon comes from watching my own Red Dragon flame thrower start the duct hose on fire. The fan effectively forced the flames and debris into my engine compartment. I almost lost my plane that morning. No surprise given what that heater is and how it works. That was the last time I used one. It was always inconvenient to use and not very good for the job. A lot of heat spent on anything inside the cowl and not well directed to what needed heating.

My own coldest preheat was at -44*. I used my 1000W gennie and Reiff heater for 4 hours. My coldest start was in single digit temps with a huge storm coming in. It was literally a black wall. I had to go now or stay for days. No time for a good preheat. I started my 0-520 after turning the prop several times by hand to loosen things up. It fired and with steady feeding of the primer I kept it running. Not ideal but in that case it was necessary.
 
Another benefit of my Reiff system, and the same would be true for Tanis, is with directly applied heat I don't need as much thermal insulation in my cover. I had an engine cover made with half the insulation that most covers have. It's much easier to carry and my covers go with on every winter flight. The pic shows my wing, tail, windshield, prop, spinner, and engine covers tucked into the compression sack that's sewn onto an inner seam of the engine cover. The bale of covers is smaller than a familiar Honda 2000 generator. Now THAT's handy!
 

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Stewartb said:
My own coldest preheat was at -44*. I used my 1000W gennie and Reiff heater for 4 hours. My coldest start was in single digit temps with a huge storm coming in. It was literally a black wall. I had to go now or stay for days. No time for a good preheat. I started my 0-520 after turning the prop several times by hand to loosen things up. It fired and with steady feeding of the primer I kept it running. Not ideal but in that case it was necessary.
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I had a few starts in 10F with no preheat on the Aztec. I had one time when it simply wouldn't start one engine, although usually it would start. It would be coughing and sputtering for a few minutes until all 6 cylinders kicked in, though.
 
Stewartb said:
Do you have one? Is that what you use?

I've had one for 20+ years. Red Dragons suck. They're dangerous and they do a crappy job of preheating an airplane. There are lots of better options.
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Wondering why you dislike the red dragon and why you feel they are dangerous. I use a generator to power the oil pan heater for 3 hours or so then put the red dragon on for 30 to 40 minutes to warn the cylinders. Seems to work good for me.

I will say the red dragon is a small PITA. Propane bottle, hook up to 12V to run the fan. I have a 4 inch hose 12 feet long to direct the warm air into the engine. I run the fan motor off a battery charger powered by the generator. I always babysit the red dragon when I use it.
 
How about a technical question for Ted?

When I rebuilt my Lycoming with assistance from a very experienced engine builder we wanted to be in the middle of the ovehaul manual's bearing clearnce tolerances for main and rod bearings. He specifically didn't like tight clearances. I assume the specified clearances are to normal room temperatures but don't recall that being addressed. If room temperature is the standard, what would the clearance variable be at say... 30*? How about 0*? Is there any published info about aircraft engine clearances in different temperatures?
 

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Stewartb said:
How about a technical question for Ted?

When I rebuilt my Lycoming with assistance from a very experienced engine builder we wanted to be in the middle of the ovehaul manual's bearing clearnce tolerances for main and rod bearings. He specifically didn't like tight clearances. I assume the specified clearances are to normal room temperatures but don't recall that being addressed. If room temperature is the standard, what would the clearance variable be at say... 30*? How about 0*? Is there any published info about aircraft engine clearances in different temperatures?
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I think being in the middle of the tolerance is generally a good idea with respect to bearings on these engines. The tolerances were not meant to be optimal, they were meant to be functional. I don't have (and don't recall) any charts that showed clearances at various temperatures, but that data was calculated at some point in time years ago when these engines were designed.
 
Stewartb said:
My mechanic's father tells stories of winter hunting for polar bears in Cubs. He doesn't talk about getting them started as much as keeping temps up while flying low and slow. They came up with some cool ideas for cowl flaps. Those old-timers were tough dudes but they don't act like it was anything special.
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Somewhat OT but does relate...

During the multi CFI ride we were seeing -18C at 11,000 and had to do a full engine shutdown of course, to meet the requirement.

During the shutdown and restart demo, the engine's single point temp probe fell to 67F. Poor engine, we had to restart it cold. It went from 275F to 67F in the amount of time to shut it down, demo feathering it, and restart it with a 120 knot dive to assist.

Didn't feel "right" but wasn't much choice. I really hate beating up other people's gear.

Usually in that airplane we keep the MP at 15" until the single point probe says the engine is back up to 200F at least before applying any more power. We couldn't get it above 175F at 15". Had to baby it back up in temp.

Sure as heck wasn't going to pour the coals to a cold turbocharged engine right after starting it up at 67F, that's for sure.

Did I mention we chose the engine that normally runs a little hotter on purpose? I wonder how cold the other one would have gotten.

Irony: We had preheated both engines on the ground for a couple of hours prior to the flight. Ground temp was forecast to be 40F and was really just above freezing. Maybe 34F.
 
I've been told by other Connie flight engineers that they have shut down the 3350s and watch them ice up to the point they would not come out of feather.
 
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We're we talking about draining oil and setting it on the stove in the kitchen? This is a fun read.
 
Playing with numbers for differential expansion - You can figure 160 degF for .001 inch per inch differential expansion between aluminum and steel.

Thus a Lycoming main bearing fitted to .0011 clearance (the minimum main bearing clearances from the obsolete Lyc manual I looked at) of a 2 3/8" diameter crank main diameter at 68 degF will be at zero clearance at -6 degF.

Probably even more critical, is the increase in viscosity of the oil at low temperatures. The engine manufacturers seems to have established a limit viscosity of about 2000 Centistokes for unassisted cold start although some of you seem to have pushed this to 5000 (!) Cst.

At the other end of the temperature spectrum at a max temperature of 220 degF the typical viscosity is about 15 centistokes. The leakage out of a clearance is roughly proportional the cube of the clearance and inversely proportional to the viscosity. By playing some more with the numbers the lube volume to all of an engine's expensive surfaces (cam, followers, cylinder bores etc) can easily vary by a factor of 1000.
 
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Are there any reasonably sized deep-cycle batteries that would have enough juice to heat the engine?
 
Man this is all fairly primitive.

Any portable generator is going to put far more energy in heat down its exhaust pipe than it will through any wires. So if you have one of those, why not just duct the genset exhaust into the engine compartment and call it good?
 
Atypicalguy said:
Man this is all fairly primitive.

Any portable generator is going to put far more energy in heat down its exhaust pipe than it will through any wires. So if you have one of those, why not just duct the genset exhaust into the engine compartment and call it good?
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Many will claim that the exhaust gasses and moisture are corrosive. But others will use propane burners which also make exhaust and moisture. I used a weed burner and some gutter downspouts for two winters. There is always the chance of setting the plane on fire, but everything carries risks.

I used a small generator to run an electric heater inside the airplane to warm it up while the weed burner heated the engine. Could have killed two birds with one stone.
 
Could also just run some flexible duct for the exhaust into the cowl and run the end out again, capturing the radiant heat from the duct but avoiding the soot etc.

I remember using a wood stove, a shower exhaust fan and some dryer duct with a foam box to post cure some international canoe hulls we made with resin inusion one time. Target mold temp was 170 inside the foam box before running the resin in. Similar to this Northern buddy thing except combustion gases still went up the chimney.
 
Atypicalguy said:
Could also just run some flexible duct for the exhaust into the cowl and run the end out again, capturing the radiant heat from the duct but avoiding the soot etc.

I remember using a wood stove, a shower exhaust fan and some dryer duct with a foam box to post cure some international canoe hulls we made with resin inusion one time. Target mold temp was 170 inside the foam box before running the resin in. Similar to this Northern buddy thing except combustion gases still went up the chimney.
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You only get radiation heating with that method, so not a lot compared to radiation, convection, and conduction when the hot gasses are swirling around the cylinder fins. But it is not a bad idea, since I have an oil pan heater to use the generator for the oil pan and interior heaters, plus get sone extra heat from the exhaust at the same time. I just don't see it working on its own very well.
 
I agree. Radiant heat sources need to be super hot to be effective.
 
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