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December 4th, 2006, 12:50
| #1 |
| Senior Member  Join Date: Oct 2006 Location: Tempe, AZ
Posts: 460
|  Does frost alter the shape of airfoil?
I had a test question and the prof is claiming that only ice and snow disrupts airfoil. But gleim words it like it is. If anyone has a link to any faa website or any online source please let me know.
__________________ I am a firm believer that a fulfilled life is a life lived goal to goal. TT 76.2 hours  First Solo: 12/9/06  Private Pilot ASEL: 5/9/07 |
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December 4th, 2006, 13:12
| #2 |
| Moderator  Join Date: May 2003 Location: GRR
Posts: 8,632
| Re: Does frost alter the shape of airfoil?
Which question are you asking: "Does frost alter the shape of the airfoil?" or "Does frost alter the flow of air across the airfoil?" NASA Aircraft Icing Programs. "A Pilot's Guide to Ground Icing" has some pretty good information on frost and its affects.
__________________ . If life gives you lemons, throw 'em into a quart of vodka. ~Red Green |
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December 4th, 2006, 13:36
| #3 | |
| Senior Member  Join Date: Aug 2006 Location: Olathe, KS/ Grand Forks, ND
Posts: 421
 | Re: Does frost alter the shape of airfoil?
The frost disrupts the smooth flow of air across the airfoil. In the Gleim Private Pilot, Page 26, section 1.5. Quote:
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December 4th, 2006, 13:42
| #4 |
| Senior Member  Join Date: Aug 2000 Location: Salt Lake City
Posts: 632
| Re: Does frost alter the shape of airfoil?
No one takes off with it on their wings in the part 121 world. Gotta get de-iced.
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December 4th, 2006, 18:01
| #5 | |
| Senior Member  Join Date: Apr 2004 Location: abe
Posts: 868
| Re: Does frost alter the shape of airfoil? Quote:
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December 4th, 2006, 19:40
| #6 |
| Newbie  Join Date: May 2006
Posts: 6
| Re: Does frost alter the shape of airfoil?
Yes, even small amounts of frost can change the shape and airflow over an aircraft's surfaces. Frost reduces performance and changes flight characteristics by increasing drag and reducing max lift.  |
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December 4th, 2006, 19:58
| #7 |
| Moderator Join Date: May 2003 Location: GRR
Posts: 8,632
| Re: Does frost alter the shape of airfoil?
<moved to Tech Talk>
__________________ . If life gives you lemons, throw 'em into a quart of vodka. ~Red Green |
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December 4th, 2006, 21:22
| #8 | |
| Senior Member Join Date: Oct 2006 Location: Tempe, AZ
Posts: 460
| Re: Does frost alter the shape of airfoil? Quote:
How ever, the airfoil shape stays the same? I think I got my words mixed up on the test. 
__________________ I am a firm believer that a fulfilled life is a life lived goal to goal. TT 76.2 hours First Solo: 12/9/06 Private Pilot ASEL: 5/9/07 | |
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December 4th, 2006, 21:53
| #9 | |
| Old Skool Join Date: Sep 2006 Location: Memphis, TN
Posts: 2,448
| Re: Does frost alter the shape of airfoil? Quote:
Frost does not change the basic aerodynamic shape of the wing, but the roughness of its surface spoils the smooth flow of air thus causing a slowing of the airflow. This slowing of the air causes early air flow separation over the affected airfoil resulting in a loss of lift. A heavy coat of hard frost will cause a 5 to 10 percent increase in stall speed. Even a small amount of frost on airfoils may prevent an aircraft from becoming airborne at normal takeoff speed. Also possible is that, once airborne, an aircraft could have insufficient margin of airspeed above stall so that moderate gusts or turning flight could produce incipient or complete stalling.
__________________ Core Concepts of Flight If an error is corrected whenever it is recognized as such, the path of error is the path of truth --Hans Reichenback | |
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December 5th, 2006, 08:35
| #10 |
| Old Skool  Join Date: Sep 2003
Posts: 1,888
| Re: Does frost alter the shape of airfoil?
An interesting sidebar to this conversation is FAA SAFO 06014 (Safety Alert for Operators) and how it expands upon FAR 91.527. The FAR states that you can takeoff with frost on your wings if it has been polished smooth. However the SAFO states that you should only peform this procedure in accordance with an aircraft manufacturer's recommended procedure. A review of various manufacturers shows that none have an approved procedure for frost polishing. A SAFO is a safety recommendation and is not regulatory...but verbage in the SAFO hints that regulatory changes may be in the works. You can view these at http://www.faa.gov/other_visit/aviat...ne_safety/safo. |
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