Cold Weather Aerobatics

[Crankshaft]

With the winter approaching in Europe I wonder what precautions other aerobatic pilots normally take when it comes to cold weather.

Where I live it typically is about -10 to +5° C (at ground level) in winter time. No limitations is given in my POH but I remember since I used to do aeros in gliders that a few of them (composite a/c) had load restrictions below certain temperatures due to the decreased structural stress tolerance in low temperatures.

How do you anticipate for this? No aerobatics at all or only low g manoeuvres? Any typical temperature you wouldn't fly aeros below, etc.

[Torque Tonight]

I have done aeros in a few different types and have never encountered a temperature limit - but they have all been metal, not plastic aircraft.

My favourite flying weather is the cold, clear winter day with infinite visibility. Perfect for aeros and the cold conditions will give you a few extre horsepower to play with.

[alphaLaura]

I reach my own temperature limitations well before the airplane does! I flew in very cold conditions last winter and spent a long time on the ground getting the temperatures up off the stops, but from an engine management perspective, when it's ready to fly, there will be no rough running during power checks. The POH says I can start the aircraft once it's more than -20 Celsius OAT. Whether I would enjoy flying upside down while it's -20 celsius is another consideration...

[Pilot DAR]

In the case of any certified areobatic power plane, it is very unlikely that there would be changed structural limitations based upon temperature. I would be very careful, however, with engine management. The rapid and complete power changes during some maneuvers are really hard on cylinder cooling. I do areobatics in the winter, but they are kind of sloppy, 'cause I do not operate the engine to extreme. With good engine monitoring equipment, you can notice cylinder head temperature changes exceeding 100F per second, if you're not very careful.

Have fun, enjoy the good vis, and very stable air, but consider the person who'll have to pay for engine maintenance one day....

[Unusual Attitude]

"I do areobatics in the winter, but they are kind of sloppy, 'cause I do not operate the engine to extreme."

....must remember to use that excuse next time my aero's are a bit 'gash'! ;)

[ShyTorque]

If in doubt, check the flight manual for the temperature envelope for which the aircraft is certified.

[RatherBeFlying]

Check the manufacturer's manual for such things as extra baffles on the cowl intake. Cooling the engine too fast is not nice to the engine, especially pulling the throttle to idle when pointed straight down and rapidly gaining airspeed:eek:

While I may happily pull the engine completely to idle turning base; when it's -20C up there and there's no baffles, I'm inclined to leave it at 1500 rpm. Use extra flaps or sideslip for more descent rate.

Remember that most of the wear and tear on the engine occurs during the first 30 seconds of starting and that preheat decreases that wear.

[Crankshaft]

I appreciate your thoughts. Thank you!

But the reason for my original concern is not the engine iself. Also I am quite confident that the main structure of the aircraft such as wing spars or fuselage can withstand the G-loads even in cold weather.

What I really think about is other components of the aircraft that might not have direct impact on the safety. When carrying out a high g manoeuvre you get some bendings on the wings for example. The wing spar takes the load but everything attached to it also gets a share of the bendings and twistings: Plasic fairings, fuel tanks, hinges, the painted fabric, etc. In extreme temperatures things that is normally very flexible (plastic for example) can be extremely stiff and vulnerable.

[Agaricus bisporus]

Shytorque's answer is the only relevant one.

Beyond that, if neither the manufacturer, the certificating authority nor the aviation industry as a whole (including generations of stress and design engineers)have considered this significant why should anyone start worrying about it now? After all, the effects of temperature on aerostructures is hardly a new or unforseen phenomenon.