How cold will you fly?

[flyer170]

The coldest I have flow in was -20 in an Aeronca Chief, long ago.
In my 170 -10 deg f is about it if I don't have to go any place special.
- 25 or colder I don't go any time. But this is NW WI. not AK.
I always pre heat the engine in the winter
It is difficult to keep the oil temp up. I have a survival kit plus two sleeping bags in the airplane summer and winter and adjust the contents accordingly. I always wear clothes when I'm flying that I could wear in the woods if I went down. For winter flying I really like Steiger mukluks, they are light weight, very warm and it is easy to feel the rudder pedels through the soles.
Bob

[GAHorn]

Lots of good info. I am always curious of peoples cutoff. One of my biggest concerns has been my oil temp. I have the oil sump blocked and the top half of the cowl taped off and I still only get the oil temp up to maybe 140, not to good. I have been flying pretty much once a week, all winter. My personal cut off is -30 . I wear arctic gear and a survival vest always... On another note I purchase my 53 b from a man in Kansas City MS. and flew it up a year ago. A very fun trip.

Don't worry too much about getting your oil temp up. I realize that common wisdom is to get it to 180 to "boil" out the water, but in reality anything above 100 will evaporate water if it's flown long enough, and the worst case is merely doing frequent oil changes. Most folks I know (including me) do oil changes every 25 hours/3 months even with an oil filter. Water is not going to be a problem in an engine that is flown regularly or has it's oil changed regularly. IMHO.

[futr_alaskaflyer]

Interesting...I guess that I look at it from the perspective that blocking those intakes to get your oil temp up will also serve to improve cabin heating, which at -20 or -30 is critical. With oil sump and lower air intake blocked I will cruise with an oil temp in the 170's even that cold.

Up here with the inversions you maybe taking off that cold, but can often get up where the OAT is much higher. Which makes MoonlightVFR's post so interesting. In my bird someone had removed the hose from behind the instrument panel at some point leading to the defrost and I had my A&P replace it this week.

[GAHorn]

I doubt the oil temp has much to do with cabin temp in a muffler-powered cabin heat system. Leaning it out to get max EGT and carrying a high power setting is probably more beneficial from a cabin heat perspective.

[hilltop170]

Any heater works much better when all the incoming cabin air leaks have been stopped. The obvious ones are door and window seals. Less obvious but potentially high volume air exchanges can come in from wing root areas which are pressurized or from the tail cone thru the rear baggage bulkhead or headliner depending on whether the tailcone is pressurized or not. Wing root leaks are a little harder to close up but make a dramatic difference. Leaking air vents are obvious also and can let in lots of cold. Duct tape over the wing intakes will stop that.

With everything sealed up some will ask how the hot air can get in from the heater if all the leaks are closed up. You can never seal all the air leaks into the cabin and there is leakage out of the cabin thru the flap tunnel, headliner, and other places. The air will always flow from higher to lower pressure.

The heater might flow better if an induced draft is set up somewhere in the plane. Later model 180/185s had small vents facing backwards just in front of the horizontal stab for just that purpose. The flip-side of an induced draft is how much is too much? With all incoming leaks sealed, exactly matching maximum heater air flow with outflow would seem to get the most heat into the cabin. Too much outflow will cause an increase in cold air from the outside.

I have also considered making a winter-only airscoop to slide over the heater air intake up front to effectively increase the size of the intake without actually modifying it. That small cup should flow more air into the heater muff if it was enlarged. Maybe someone has already done it?

I spent days sealing up leaks and improving airflow on the heater system in a Super Cub years ago. They are notorious for lack of heat. I made many flights locating and sealing leaks. When I was done, I could actually regulate the heat at a comfortable level to both the front AND back seat. I don't know why that couldn't be done on a 170. Has anyone tried it?

I'm going to keep my 170 in Texas and would rather have as many air leaks in and out of the cabin as possible but the guys up north could benefit from a good going-over to seal up their cabins.

I agree with George on running higher power settings and leaning aggressively. That makes a big difference no matter how bad the cabin leaks.

[jrenwick]

I have also considered making a winter-only airscoop to slide over the heater air intake up front to effectively increase the size of the intake without actually modifying it. That small cup should flow more air into the heater muff if it was enlarged. Maybe someone has already done it?

Richard,

Corey from Soldotna posted photos of this here: http://cessna170.org/phpBB2/viewtopic.php?t=3110 (toward the bottom of the first page).

I copied his idea on my '55 B-model, and it seems to work pretty well. The solution will vary for different model years, because Cessna changed the heater parts several times.

Best Regards,

John

[28Charlie]

Have you seen the cowl flaps some have made? I met a guy last week whose plane came from Wiseman with a very clean installation. He said he hasn't used it much. I would think it would be a better setup than blocking incoming air especially for the Lyc. conversions.
If your interested in another opinion on the 220 Franklin conversion, you should try Don Child. He's had his for 8 or more years now. I believe he had 60 lbs. of lead in the tail for balance. He's a member in AK. Use to fly for Reeves. Chuck

[hilltop170]

John- Thanks for the link to Corey's air scoop. That's what I had in mind.


Chuck- All of the cowl flaps I have seen have been there to increase the airflow to increase cooling. I would be real hesitant to decrease airflow with cowl flaps to increase engine temperature. That could be real risky, IMHO.

[GAHorn]

RIGHT-YOU-ARE, RICHARD!! Cowl flaps are to increase cooling at low airflow/high power situations such as during takeoff and climb. They are then closed to reduce excess drag during cruise and excess cooling during descent. A Cylinder Head Temperature gauge is FAR required equipment with any installation using cowl-flaps.

[hilltop170]

Went flying today, OAT was 15°F, CAVU, no wind, no turbulence.

With nothing more than tape blocking the front oil sump opening and both blast tubes to the oil pump/strainer housing, oil temp ran 185°F.

[thammer]

It almost looks like you crawled into the back seat to take that picture!

tye

[hilltop170]

Tye-
I just moved the pilot seat back, leaned against the door, and held the camera over the back seat. It works pretty well but I had to take several to get a good one. Don't know how I ever got good pictures before the digital cameras came along.

[GAHorn]

Can't quite make out the altitude. 4K? or 14K?

[cessna170bdriver]

Can't quite make out the altitude. 4K? or 14K?

Ah, George, more evidence of your advanced dotage? (Or maybe you need a computer built this century...)

The 10,000-foot hand on the altimeter is fairly evident to me. When I first saw this picture I remember noting that it is about at low-pass altitude in Tehachapi. I was wondering if the 14.1 on the gauge below the rate of climb is voltage or OAT.

Miles

[hilltop170]

George-
The water in front of the plane is at sea level, ±20'. It's called Turnagin Arm, just east of Anchorage, and was named by Capt. Cook in the 1700's while he was exploring for a passage to the Gulf of Alaska. After trying several dead ends, when they ran out of water at the end of the arm they had to "turn again".

I was at 4100'. Years ago I did climb this plane to 17,500' though. I started climbing at Odessa and got to 17,500' just in time to descend to Lubbock to take my Commercial written exam. My nails were a little blue and I had a headache (made a 93% on the test). The engine was REALLY quiet too, probably because it wasn't making much horsepower or maybe your hearing goes out with lack of oxygen, I don't know. BTW, I was about 25 years old at the time and routinely had "good ideas" like that. Luckily I lived thru them all.

Miles-
I flew thru Tehachapi Pass last September. Those wind turbines could sure ruin your day. The 14.1 is voltage, probably a little high for the Concorde sealed battery? OAT is still in the air vent. With all the air leaking into the plane while the interior is out, it felt more like -14°F with the wind chill.

Here's a better picture of the panel. The stall warning, knobs, piano keys, and plexiglass checkered panel are just about all that is original. I would sure like to find a 44" long cable with a pink knob to replace that black knob.