Canard Community Forum  

Go Back   Canard Community Forum > Finishes and Finishing
FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #16  
Old 06-13-2007, 11:24 AM
Waiter's Avatar
Waiter Waiter is offline
LongEZ-RG
 
Join Date: Dec 2004
Location: Northwestern Ohio
Posts: 1,096
Default Re: COLOR vs TEMPERATURE

I love this stuff

My neighbors have given up:

They are used to seeing me at all hours of the days and nights with wierd gadgets, lights, and other strange looking gizmos, shining them into the sky, on buildings, and at the ground.

i.e.; How many of your neighbors have a fully assembled airplane sitting in their back yard?

Waiter
__________________
F16 performance on a Piper Cub budget
LongEZ, 160hp, MT CS Prop, Downdraft cooling, Full retract
visit: www.iflyez.com
Reply With Quote
  #17  
Old 06-20-2007, 10:42 PM
DustinD DustinD is offline
Member
 
Join Date: Jul 2004
Location: Saint Michael, MN
Posts: 128
Default Re: COLOR vs TEMPERATURE

For what it is worth the back of your hand is better than your palm at sensing temperature. I found that the back of the skin right after the knuckle at the root of my fingers was the best. It also has the lowest thermal mass effect, partially because I can get a "reading" a bit faster. Not that this will help you with your problem though.

Maybe if you use a thermocouple you could drag it slowly over the surface. That way the thermocouple can get up to the same temp as the FRP.

I am also interested in what you find out about how much of an effect different shades of gray have on the temperature.

I wonder if you could find some sort of paint that is more reflective of IR, but also has good emissivity. I know with some materials they can be great at absorbing IR, but also be poor at emitting it.
Reply With Quote
  #18  
Old 06-21-2007, 09:06 AM
Jack F. Jack F. is offline
Actively building
 
Join Date: May 2005
Location: Moorestown, NJ
Posts: 58
Default Re: COLOR vs TEMPERATURE

Quote:
Originally Posted by DustinD View Post
I wonder if you could find some sort of paint that is more reflective of IR, but also has good emissivity.
One of the guys from the local EAA chapter told me that Cirrus is now painting their planes in colors other than white. He said something about a paint breakthrough. I couldn't find anything on the web about it, other than the cirrus website showing pics of planes in gray shades. Can anyone offer additional information about this rumor?

Jack Fairchild
Winning the fight with the FHC hinges!!!
Reply With Quote
  #19  
Old 06-21-2007, 09:29 AM
Waiter's Avatar
Waiter Waiter is offline
LongEZ-RG
 
Join Date: Dec 2004
Location: Northwestern Ohio
Posts: 1,096
Default Re: COLOR vs TEMPERATURE

During my research, I googled for paints that offered high reflectivity (low absorption) in wavelengths above 800nm (above the visible range).

I did find a couple test reports, but the temperature differences between the normal and the high reflective was only about 5 degrees.

If you find anything, by all means, let me know.

Waiter
__________________
F16 performance on a Piper Cub budget
LongEZ, 160hp, MT CS Prop, Downdraft cooling, Full retract
visit: www.iflyez.com
Reply With Quote
  #20  
Old 06-21-2007, 10:57 AM
Clutch Cargo's Avatar
Clutch Cargo Clutch Cargo is offline
w/ Spinner and Paddlefoot
 
Join Date: May 2004
Location: Cape Coral, FL
Posts: 602
Exclamation Re: COLOR vs TEMPERATURE vs HEAT vs MELting...

I think (which means my opinion is...) that it would be a good idea to find out at what temperature the foam (behind the hardened epoxy/fiberglass shell) starts to degrade.
When Mythbusters did a peice on the temperature on the inside of cars, (trying to see if a biscuit container and other items would explode if left in a hot car) the mean temp was around 140 degrees inside. Black objects will give up heat to wind and normal convection in calm air. Swimming pool heaters and some "pre-heaters" warm the water prior to going into the hot water heater to save energy. The water temp coming out of a (previously static) flow is in the mid 160's F. However, if you focus the sun's energy you can get up to 250 degrees F! I don't think you would do that to your airplane!
It's in the lower 90's here in FL. So, I just took my trusty Fluke 61 infrared thermometer and did some sampling: (all in degrees F., all 5 hours in direct sunlight)
1. Hot tire: 157
2. White painted surface:114
3. Shiny black painted surface: 124
4. Dull black painted surface: 132

The hot tire wins because it's dull and black and the air inside doesn't take any heat away. It's heat loss is going to be due to convection.

Now, water boils at 212 degrees at sea level, (Im 21 ft above sea level) I wonder what the first type of foam would melt? How much of a margin could you live with? How bad do you want your airplane to be black? Isn't it enough to have a "snarky" looking airplane? But, "snarky" and black?
If the answers to the above questions were all "yes", then you didn't read all the questions!

I did some research on latitude and it seems the further north you are the less effect the sun's rays have on heating, ie. It takes much more area up north to attain the same "heat" factor as down in the lower (closer to equator) latitudes. (unless you're in the southern hemisphere, then "up" (north) is warmer).

So don't be a "Chicken Little" ("The sky is falling, the sky is falling"!) till you do the "Chicken Little" dance!
__________________
Plans #618, a tub, and everything I need to go to chapter 11 except: TIME! and a cold beer

"I'll do the "thinnin'" around here, Bobba Looey" ! - Quicksdraw McGraw
Reply With Quote
  #21  
Old 06-21-2007, 11:09 AM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: COLOR vs TEMPERATURE

Eracer had dark purple on his leading edge, when he cut them off to redo, he does that kind of thing in his search for perfection, he reported no foam problems, he was happy.

good point clutch, i think in my future testing i will do it on a mocked up wing section.
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #22  
Old 06-21-2007, 11:13 AM
TMann's Avatar
TMann TMann is offline
Got Foam?
 
Join Date: Mar 2007
Location: Omaha, NE
Posts: 756
Default Re: COLOR vs TEMPERATURE vs HEAT vs MELting...

Quote:
Originally Posted by Clutch Cargo View Post
Now, water boils at 212 degrees at sea level, (Im 21 ft above sea level) I wonder what the first type of foam would melt?
I have 4 types of foam in the oven in the kitchen right now and should have an answer for you shortly (provided I can finish this experiment and get the house aired out before my wife gets home!)
__________________
T Mann - Loooong-EZ/20B Infinity R/G Chpt 10 N200LZ
Got Foam?
Mann's Airplane Factory
We add rocket's to everything!
Reply With Quote
  #23  
Old 06-21-2007, 12:07 PM
WileEZ's Avatar
WileEZ WileEZ is offline
No Freaking Clue!
 
Join Date: Apr 2007
Location: Kirkland, WA
Posts: 56
Default Re: COLOR vs TEMPERATURE

I'm interested in this!

I have a killer paint job in mind I would like to use on my airplane.

Maybe I should build a trike with an enclosed body canard style, something like the one below and paint it to see how well it would handle the sun?

By canard style I meant, an outer layer of BID, and three layers of uni (90 degrees, 45 degrees and 135 degree) with 1/2" diviny foam and the innermost a layer of BID.

Hmm I really need to find me a shop to work in somewhere.

WileEZ
Attached Thumbnails
Click image for larger version

Name:	1981-_Feora_big.jpg
Views:	42
Size:	128.6 KB
ID:	3783  
Reply With Quote
  #24  
Old 06-21-2007, 06:03 PM
DustinD DustinD is offline
Member
 
Join Date: Jul 2004
Location: Saint Michael, MN
Posts: 128
Default Re: COLOR vs TEMPERATURE vs HEAT vs MELting...

Quote:
Originally Posted by TMann View Post
I have 4 types of foam in the oven in the kitchen right now and should have an answer for you shortly (provided I can finish this experiment and get the house aired out before my wife gets home!)
Are you sure that radiant (if it is electric) or uneven heating inside the oven is not going to fudge the results? you may need a heat spreader or IR blocker.

If you put the samples on a metal pan with aluminum foil to protect the pan from melted foam goo, and then put tinfoil on the top and bottom rack to stop direct radiant heating it may work better.
Reply With Quote
  #25  
Old 06-21-2007, 06:09 PM
TMann's Avatar
TMann TMann is offline
Got Foam?
 
Join Date: Mar 2007
Location: Omaha, NE
Posts: 756
Default Re: COLOR vs TEMPERATURE

D@mn...... Your right! I should have used a cookie sheet at least. I don't think I'm going to get all this melted goo cleaned up before she gets home. I shouldn't have just put them on the rack.

Ha! what was I thinking ......... this is a self cleaning oven. Anybody know how long the clean cycle takes to clean up this mess? She gets home in 2 hours so if I start the cycle now I might make it.
__________________
T Mann - Loooong-EZ/20B Infinity R/G Chpt 10 N200LZ
Got Foam?
Mann's Airplane Factory
We add rocket's to everything!
Reply With Quote
  #26  
Old 06-21-2007, 06:27 PM
TMann's Avatar
TMann TMann is offline
Got Foam?
 
Join Date: Mar 2007
Location: Omaha, NE
Posts: 756
Default Re: COLOR vs TEMPERATURE

well ....... that sure could have gone a lot better.
Attached Thumbnails
Click image for larger version

Name:	FoamTest2.gif
Views:	24
Size:	44.2 KB
ID:	3784  
__________________
T Mann - Loooong-EZ/20B Infinity R/G Chpt 10 N200LZ
Got Foam?
Mann's Airplane Factory
We add rocket's to everything!
Reply With Quote
  #27  
Old 06-21-2007, 11:39 PM
eracer113 eracer113 is offline
Member
 
Join Date: Nov 2004
Location: aurora, Illinois
Posts: 197
Default Re: COLOR vs TEMPERATURE

Dust is correct on the dark purple paint on my E Racer. When I cut the winglets off my wings, which had been on the AC painted dark purple for 10 years, I could not see any deterioration of the foam or glass. The AC had sat in 92-93o heat for two-three days at a time. I will bring the cutoffs to Osh for anyone who would care to inspect them. I'm not sure there is an accurate way of measuring just how far into the glass the heat will go on an assembled and painted surface. Does the heat partially dissapate as it passes through the paint, primer, bubbles, and glass before it reaches the foam? All I know is it certinally did no damage to the foam in my wings over a long time period.

Jack
E Racer 113
Reply With Quote
  #28  
Old 07-18-2007, 07:28 PM
WileEZ's Avatar
WileEZ WileEZ is offline
No Freaking Clue!
 
Join Date: Apr 2007
Location: Kirkland, WA
Posts: 56
Default Re: COLOR vs TEMPERATURE

Steve Parkins and I did an experiment while I was in his "hanger" last Sunday.

We took a piece of completed fiberglass/PVC foam layup that Steve cut off from his strakes and set it up with a heater radiating heat on it as shown in the picture below.

We used a calibrated IR temperature sensor to measure the temp. Steve held it really close to the surface to make sure we're not measuring something else.

After a couple minutes the outside surface temp was 178 degrees (F), inside temp was 118 degrees (F) and the core (before drilling) was 86 degrees.

We left it for about an hour and came back and remeasured. Outside temp was 172 degrees, inside was still 118 degrees and Steve drilled a hole in the leading edge core foam and the temp was 123 degrees (all F).

We checked the foam to fiberglass laminate and could not peel it apart. We tried crushing it with our fingers and couldn't tell the difference between hot and cold crush. The foam might have gotten soft, but it was hard to tell the difference, if any.

I guess we'll need someone to make up a piece of foam laminate and paint it flat black and leave it out in the southern sun for, oh say, six months to a year and see what happens.

Anyone in the desert willing to do such a test?

WileEZ
Attached Thumbnails
Click image for larger version

Name:	S6300023.JPG
Views:	36
Size:	275.3 KB
ID:	3936  
Reply With Quote
  #29  
Old 07-18-2007, 07:45 PM
Marc Zeitlin Marc Zeitlin is offline
Member
 
Join Date: May 2004
Location: Tehachapi, CA 93561
Posts: 1,083
Default Re: COLOR vs TEMPERATURE

Quote:
Originally Posted by WileEZ View Post
We checked the foam to fiberglass laminate and could not peel it apart. We tried crushing it with our fingers and couldn't tell the difference between hot and cold crush. The foam might have gotten soft, but it was hard to tell the difference, if any.
That's Divinycell, which has a published maximum operating temperature of 70C-85C (158F - 185F).

Styrofoam is listed as having a temperature limit of 75C (167F).

Assuming that you measured correctly, you didn't get the foam to any of those temperatures with your heating method (which doesn't mimic the heat transfer properties of a horizontal wing with 8" of styrofoam in it).
__________________
Reply With Quote
  #30  
Old 07-18-2007, 10:46 PM
coolamber coolamber is offline
Member
 
Join Date: Apr 2007
Location: Henderson, NV
Posts: 70
Default Re: COLOR vs TEMPERATURE

I live in Las Vegas. I could put a piece of black painted foam outside for this test. I have a large enough backyard and could find a suitable spot for this experiment.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 01:03 PM.


Powered by vBulletin® Version 3.6.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.