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  #31  
Old 12-27-2012, 08:28 AM
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dhammer dhammer is offline
 
Join Date: Nov 2007
Location: Keller, TX
Posts: 151
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Quote:
Originally Posted by David Z View Post
As I had it explained to me, the -40 cutoff is because that's where the steel axels and other metal parts get too brittle. It also takes noticably more power to taxi because the wheel grease is so thick.
Used to fly into the Alaska North Slope where I've seen less than-65F. The cutoff for turbine aircraft wasn't the outside temp, but what happens inside. At altitude the standard temp is -57C and the gear etc gets that cold every flight.

Jet A starts to jell at -40C and engines are limited to -40C on the oil temp for starting because it does the same thing. While there on site visits we used Jet B (-50C) and ran the engines every half hour so we didn't get stuck there until spring thaw.
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  #32  
Old 12-27-2012, 09:05 AM
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kevinsrv7.com kevinsrv7.com is offline
 
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Posts: 145
Default Canopy and the cold

Does anyone have bad experiences with cracked canopies?
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  #33  
Old 12-27-2012, 09:37 AM
mtnflyer mtnflyer is offline
 
Join Date: Jul 2007
Location: granby co
Posts: 180
Default 20V @30 below

A newly purchased RV 4 was pulled out of a heated hanger on a 30degree below zero morning, he was on his first cross country and taking the 4 home back east, when the canopy cracked in about 5 different places.... They spent about two hours stop drilling, safety wiring and duct taping then he was off. I had just spent my life savings on ordering my own 4 kit so it was a good lesson on the care and feeding of these airplanes....
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  #34  
Old 12-27-2012, 05:44 PM
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bweiss bweiss is offline
 
Join Date: Sep 2006
Posts: 155
Default Temp limits

My personal limit (because I think you should have one) is zero F. The reason for 0 and not -5 is it is easy to remember. My rationale is simply that if I had an off field landing I felt I could survive longer in zero on the ground than -5 F on the ground.
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  #35  
Old 12-28-2012, 06:03 AM
IFlySlow IFlySlow is offline
 
Join Date: Dec 2010
Location: Reading, PA
Posts: 59
Default ummmm.....

Quote:
Originally Posted by kevinsrv7.com View Post
Does anyone have bad experiences with cracked canopies?
I doubt anyone has any GOOD experiences with cracked canopies!
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  #36  
Old 12-28-2012, 10:06 AM
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Ironflight Ironflight is offline
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Join Date: Jan 2005
Location: Dayton, NV
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Quote:
Originally Posted by kevinsrv7.com View Post
Does anyone have bad experiences with cracked canopies?
Yup - I can cite several cracked canopies on RV-8's that correlate with cold weather - at least two of them on the same bird (sorry "Doll"....). The Val's canopy cracked after a cold night at Big Bear, followed by hitting some significant bumps in turbulence shooting down to LA.

Speculation is that this is more common with the -8's because of the long canopy....but that is, of course, anecdotal. I have yet to hear of it happening on other models.

Paul
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RV-8 - N188PD - "Valkyrie"
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  #37  
Old 12-28-2012, 10:07 AM
49clipper 49clipper is offline
 
Join Date: Dec 2006
Location: Belleville
Posts: 306
Default 49clipper

How about temps for the oil in cold weather? I fly all winter, but not normally below about 15f due to comfort, but I can't keep my oil over 150f even at 30f oat. I bypassed my cooler (since it did no good to block it off completely), checked the sensor (and found it to 14 degrees low), and even only put in six quarts of oil and the change, and I can only get 150f on the oil. I am down to trying to block off the exit area in order to warm it up. CHTs are all from 160-225 at 30f outside. Lycoming says no less than 165f on the oil, but I can't get there.
Any ideas?
Jim
RV-6 O-320-D1A carbed.
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  #38  
Old 12-28-2012, 05:53 PM
humptybump humptybump is offline
 
Join Date: Feb 2011
Location: USA
Posts: 3,179
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Quote:
Originally Posted by DonFromTX View Post
To be a real wimp, move down here! We call Dallas waaaaaaay up North in Yankee land.
Had to look for your location. I did my primary flight training south easy of you. We called it "North Mexico"
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  #39  
Old 12-28-2012, 08:17 PM
Don Blackburn Don Blackburn is offline
 
Join Date: Jan 2005
Location: Cochrane, ON Ca
Posts: 3
Default Flying in cold weather

Up here in Northern Ontario, Can. We fly down to 0 degrees F or about -20 C. Hoping it we rise during the day while out Ice fishing.... Just plane fun. Sorry for the pun.
Working Wings of a RV- 4
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  #40  
Old 12-29-2012, 07:14 PM
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Alan Carroll Alan Carroll is offline
 
Join Date: Jul 2007
Location: Madison, Wisconsin
Posts: 778
Default cracked canopies

Back when I was building I was curious about the effect of cold on plexiglass. I did some experiments with small samples that I made by riveting together two squares of plexi with the aluminum pop rivets used to hold the canopy to the frame. The squares where assembled with their edges slightly offset, so that I could put stress the rivet holes by clamping the assembly edge-wise in a vice.

The assemblies then went into the freezer overnight. I put them in the vice immediately after they came out, and squeezed. The net result of several such tests was that I was repeatedly able to shear the pop rivets, but never did manage to induce a crack in the plexi! From this I drew two conclusions: 1. plexi is strong stuff, and 2. moderate cold, by itself, does not necessarily make it crack.

I'm not sure what this means in the real world, but I suspect that cold helps existing cracks to propagate but doesn't actually cause them. Since doing the tests I've flown my RV-8 through 7 northern winters, commonly in 0?F temps and below. My canopy skirt does show some evidence of movement of the aluminum rivets (paint cracks above the heads in the aft skirt), but no there are no cracks in the canopy (yet).
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