RunRyder - Cold Weather and Engines

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Audacity Models Pantera 50 - Tiger 50 > Cold Weather and Engines

Herc
Key Veteran
Location: Cranbrook, BC - Canada

What does the Tiger crowd know about engines and the cold?

Today I got in 8 flights - 4 in the morning and 4 in the afternoon. Our temperature this morning was -20C and I would say it was -17 when I started flying. My normal engine temp is around 210F and this morning I couldn't get above 197. I had less lift than normal too. My climbouts were slower. This afternoon I went out at about -10 and same thing. Couldn't get the temp over 197. Seemed such an odd number. My temp guage seems to be working, so my questions are:

Does cold affect lift? Does the cold affect engine performance? I always thought a cooler running engine performed better to a certain extent. Would 13 degrees make that big a difference? Head's tight, backplate's tight, plug is good.

A little confused. I know guys fly in the cold so what am I doing wrong?

Shayne

02-19-2006 Over year old.

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tnorris
Senior Heliman
Location: Hico, Texas

Well the answer is yes to the cold effecting your engine. If the engine does not warm up to the proper temperature then you will most likely have less overall power output. I guess you can say that there is a little more drag on the motor becuase the cold weather is not letting the metal of the engine expand to where it is happy. That is why it is not a good idea to try and break a motor in when it is cold outside. I learned this from my old rc car days.

You might also be having some problems with the bearings not liking the extended flying time in the cold weather. This would be for the same reason, the bearing actually shrunk a little in the cold and is causing drag.

This is just my 2cents worth as I am not experienced with you kind of weather. I just know how cold can effect metal. One more thing you may want to think about. If it is -10C, imagine what the wind chill factor is under the heli.

Travis

02-19-2006 Over year old.

ARMSMASTER
Veteran
Location: spokane, wa

Just another note: Colder air also changes air density and will cause the slower climbouts. We also notice this change with a difference in altitude. The air gets thinner as it gets colder. That is why more engine and power is needed in airplanes and heli's at higher elevations. This is probally your biggest problem. Hope the info helps.

Sincerely,
Perry

Caution or the Earth will Swallow you Up!

02-19-2006 Over year old.

tnorris
Senior Heliman
Location: Hico, Texas

armsmaster is correct. The problem is what is called Density Altitude. I am a UAV pilot and we have to watch the Desnity Altitude pretty good. We have a hand held device that will tell you all that sort of info. Our problem is usually in the Summer time. We are at 950ft MSL where we fly and there are days that the Density Altitude will be around 4500ft. I was not sure how the sub zero cold would effect Density Altitude as it NEVER gets that cold in Texas.

Good job armsmaster on the comment.

Travis

02-19-2006 Over year old.

z11355
rrMaster
Location: 10000 is enough time wasted.

basically, besides altitude density and it's overall affect,
the rest of the physics statements are incorrect.

lift is directly proportional to density (see fundamental lift equation).

air density is inversely proportional to temperature

02-19-2006 Over year old.

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hootowl
Elite Veteran
Location: Garnet Valley, Pa.

Commercial jet pilots love climbing in cold weather. They can shoot up like a rocket.

Denser air allows improved lift.

Member Bog Troll Club #1

02-19-2006 Over year old.

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E J Atchison
Senior Heliman
Location: Winsted, CT USA

Density altitude is a factor, but not causing your poor climbout. Cold air is denser vs very warm air less dense. Everything is based around what is called standard atmosphere which would be (if I recall correctly) sea level at 70degrees F. A cessna 150 will barley climb on a very hot humid day, but does relativley well on a cold dry day.

High temp and/or humidity will reduce lift. Your poor climbout is caused by your engine producing less power. Some rc car people actually insulate their engine to get more performance when cold (do NOT lean it because it won't get enough lube. I don't know if anyone has tried reducing the cooling on an rc heli but I wouldn't want to be the first.

I'll admit I'm not a great pilot, but I can hover with the best of them.

02-19-2006 Over year old.

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Herc
Key Veteran
Location: Cranbrook, BC - Canada

Thanks for the comments guys.

We sit at 1013m so altitude plays a little into it I guess. I know when we fly teams into the mountains we have to limit our loads. Never really thought a model would be affected to the same extent.

It just seemed that the operating temp difference of only 13 degrees was making a big difference. But, if you take into account all the other interactions (bearings, etc) then I guess you have to pay the price somewhere.

Meanwhile, I'll happily keep flying in the cold and hope it warms up soon. The weather is too beautiful - no wind and clear - to not fly. Especially when there are so many others on the board that aren't able to get out.

helishop - thanks for that last bit about not leaning the engine. That's a very good point and something I did do yesterday and then richened it again. I realized that I could possibly have been in error doing it and thought I'd better leave well enough alone.

Cheers, Shayne

02-19-2006 Over year old.

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E J Atchison
Senior Heliman
Location: Winsted, CT USA

Glad to help.

I'll admit I'm not a great pilot, but I can hover with the best of them.

02-19-2006 Over year old.

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BARTGALAMBOS
Veteran
Location: Huntsville, Alabama! U. S. A.

Ever hear of an Intercooler?

Cold dry air is the best thing going for performance. It is dense, thus the engine gets more air. So if the engine gets more air, you then need to richen the fuel setting. See what I'm getting at. So at colder temps the engine gets more air and more fuel, thus creating more power. Now having said that, the blades operate much better in cold dense air also. All around the performance of your machine increases.

If you try to fly an airplane, off the runway at the Grand Canyon, in the summer, in very humid conditions, you will see that it takes about twice (est) the runway length. The engine does not produce as much power and the wings produce less lift.

Goodluck,

Bart

Precious Metal Investor!!!

02-20-2006 Over year old.

jvanscoyk
Veteran
Location: Tucson, AZ

Another thing to be careful about...

In the cold weather you are flying the plastics in the Tiger may become pretty brittle. Just keep that in mind. I've seen guys break landing gear legs in much warmer air than you are flying at.

Jim

must go faster, must go faster.........

02-21-2006 Over year old.

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Herc
Key Veteran
Location: Cranbrook, BC - Canada

Thanks for the heads-up Jim. I flew my TRex all last winter and yes, the plastic parts do get brittle. So far I've been amazed that I've had no hard, or unscheduled landings to test the landing gear. I do have spares just in case though.

40 flights now and not even a hiccup out of the engine. Knock on wood.

Just waiting for the 3D paddles, flybar, etc to liven it up a bit and broaden that "Tiger Grin".

Shayne

02-21-2006 Over year old.

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Audacity Models Pantera 50 - Tiger 50 > Cold Weather and Engines

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