Aerodynamics Discuss the concepts of aerodynamics here

angles and dihedral

Old 10-11-2009, 11:56 PM
  #1  
pattern14
Super Contributor
Thread Starter
 
pattern14's Avatar
 
Join Date: Feb 2009
Posts: 1,241
Default angles and dihedral

Hi all, decided to replace the multiple repaired wing on my cheap parkflyer, an SDM "Skyhawk". Decided on a 2mm coreflute, cf sparred, 1.3 metre span with a symmetrical airfoil. Flat middle section, dihedral tips, similar in chord, span and design to the original. My question is related to airfoil and wing ancidence. The original wing had a very thin section under- cambered design. Would a fully symmetrical airfoil need a deffernt angle to provide the same sort of lift? It is very easily adjusted so it is no big deal to change things; I was just looking for a reasonable starting point. The plane is a floater any way, if that helps. Thanks in advance.... pictures of the original included.
Attached Thumbnails Click image for larger version

Name:	Me 163 008.jpg
Views:	140
Size:	192.4 KB
ID:	111158   Click image for larger version

Name:	Me 163 007.jpg
Views:	156
Size:	208.7 KB
ID:	111159  
pattern14 is offline  
Old 10-12-2009, 04:37 AM
  #2  
Moxus
Gremlin
 
Join Date: Jun 2008
Posts: 641
Default

a fully symmetrical wing needs angle of attack to produce any lift at all.
a non symmetrical wing, and especially a undercambered wing, will produce lift at 0 angle of attack.
however, in the air i dont thing you are going to notice. you will compenaste for it automatically by applying elevator, and its not going to be a headache.
but why do you want a fully symmetric wing, and in combination with dihedral?
the only reason that i knew for fully symmetric wings is to fly as good upside down, as the right way.
but dihedral dont work very well with that flying upside down business.
Moxus is offline  
Old 10-12-2009, 05:21 AM
  #3  
pattern14
Super Contributor
Thread Starter
 
pattern14's Avatar
 
Join Date: Feb 2009
Posts: 1,241
Default some more info...

Hi Moxus, thanks for that. The fully symmetrical wing is built in 3 sections, and will be used as a flat wing as well, with strip ailerons, at a future date. Just saved me building 3 different wings; sort of a modular concept. The experimental bug bit me a while ago and I can't shake it off...cheers...
pattern14 is offline  
Old 10-12-2009, 06:12 AM
  #4  
JetPlaneFlyer
Super Contributor
 
JetPlaneFlyer's Avatar
 
Join Date: Mar 2009
Location: Aberdeen, Scotland
Posts: 6,121
Default

Originally Posted by pattern14 View Post
Would a fully symmetrical airfoil need a deffernt angle to provide the same sort of lift?
The simple answer to that is that a symmetrical airfoil will never produce the same maximum lift as an undercambered airfoil.

As Moxus said; symmetrical airfoils are only usually only chosen on models that need to fly as well inverted as they do the right way up. When flying the right way up a symmetrical airfoil does not perform as well as one with suitable camber. A symmentrical airfoil is a bad airfoil to use on a thermal soaring type sailpane as flying speed and sink rate will be increased.

Also as Moxus said.. you will need a higher angle of attack compared to the old wing but elevator trim will look after it, you will most likely find that you need to fly noticably faster with the new wing than with the old anyway.

Steve
JetPlaneFlyer is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Lloyd
Scratch and Kit Built Aircraft
10
02-04-2009 06:11 AM
C140
ParkFlyers
6
06-03-2008 02:34 AM
Prof100
ParkFlyers
9
07-13-2007 12:19 PM
Cyprus Flyer
ParkFlyers
7
03-14-2007 11:08 AM
jconwell
Scratch and Kit Built Aircraft
2
01-14-2007 09:25 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Quick Reply: angles and dihedral


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

Page generated in 0.09472 seconds with 14 queries