Matronics Email Lists :: View topic - Strut fairing questions.

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Strut fairing questions.
Goto page Previous 1, 2

Matronics Email Lists Forum Index -> Kitfox-List

View previous topic :: View next topic

Author Message

andynfultz(at)bellsouth.n
Guest

Posted: Sun Sep 16, 2007 4:18 pm Post subject: Strut fairing questions.

John,



  Would you mind sharing what that "aerodynamic rule of thumb" is?  I'm

about to start working on my 7/8" struts in the next few weeks and would

like to streamline them as well.  I do know that a round tube causes a lot

of drag.  Thanks.



Andy F.



--

- The Matronics Kitfox-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kitfox-List

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Sep 16, 2007 4:35 pm Post subject: Re: Strut fairing questions.

I have to check from Hoerners book but i think it around 4 to 1 ratio

- The Matronics Kitfox-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kitfox-List

_________________
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/user/kitfoxflyer
Hundreds of Kitfox Movies
Most viewed Kitfox on youtube
Most popular on youtube
Highest rated on youtube

propellerdesign(at)tele2.
Guest

Posted: Mon Sep 17, 2007 12:20 am Post subject: Strut fairing questions.

Hi

  

 It depends on the Reynolds number, a cyl (tube)  with Re <10^5 have drag coefficient 1 - 1,3, and with Re >10^6 = CD  0,30

  

 With an airfoil of length 3:1  (0,333)  and Re >10^6 = CD 0,04

 with a Re under 10^5 the length have to be 5:1 (0,20) to get same drag CD 0,04 

  

 a 2" diameter tube at 100 MPH have Re 1,56*10^5  

 8" long and Re is 6,26*10^5 and CD will be 0,012  with reference to the surface area

  

 so with say total 10 meter of 2" tube the drag  will be 60-80 kg

 and with airfoil 3 kg at 100 MPH

  

 And a NACA 67-020 or NACA 67-025 will have little  more then half the drag a NACA 0020 - 0025 will have if made  correct.

  

 Jan

 [quote]   ---

- The Matronics Kitfox-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kitfox-List

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Sep 17, 2007 4:43 am Post subject: Strut fairing questions.

Dave check the ratio on the extruded spars on your  floats and let us know.

 

[img]cid:201543212(at)17092007-235D[/img]  

 Noel Loveys, RPP, AME intern

 Campbellton, Newfoundland, 

 Canada

 Kitfox Mod III-A, 582, B box, Ivo IFA

 Aerocet 1100s

 noelloveys(at)yahoo.ca (noelloveys(at)yahoo.ca)

 

 

 Do not archive

 

 

 



[quote] --

- The Matronics Kitfox-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kitfox-List

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

av8rps(at)tznet.com
Guest

Posted: Mon Sep 17, 2007 11:34 am Post subject: Strut fairing questions.

All,

  

 For any of you having a little trouble interpreting Jan's  formulas, here's the laymens formula for determining fairing sizes as I remember  it;

  

 For every inch of thickness of the  part you want to streamline, you need a fairing 4.25 times wider.  In other  words, if you have a one inch round strut tube, you will need a streamline  fairing with a 4.25 inch wide chord.  Interestingly, the shape of  streamlined chromoly and aluminum for aircraft generally do not meet this  rule, as for the most part they have too narrow of a chord (Go  figure?)   

  

 Now this is just a general rule of thumb, and it's off the  top of my head.  So if you want more technical than that, talk to  Jan...

  

 Paul Seehafer

 Kitfox IV 912ul amphib 

 [quote]   ---

- The Matronics Kitfox-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kitfox-List

propellerdesign(at)tele2.
Guest

Posted: Mon Sep 17, 2007 12:31 pm Post subject: Strut fairing questions.

Well spoken.

  

 Re number is the length in mm (millimeter) times  airspeed in m/s times 70. (there is a formula for inch, feet and miles  too)

  

 in short, wing struts is UNDER CRITICAL Re. so need  4 to 1 or 5 to1 in length versus thickness. and / or laminar layer control  ( Think golf ball) to trip the boundary layer into TURBULENT layer that have  energy to follow the airfoil.

 can be made of Dyno tape (old one) with big V typed  all the way. or cut length vise with a zigzag scissor (for fabric) and the  cut turned into the airstream, applied both side of wingstrut. at highest  point, or just forward of.

  

 CD is Drag Coefficient that relates to something  like wet area or frontal area (different coefficients) 

 To get the actual drag, CD times the reference area  times Dynamic pressure. simple as that.

  

 and at level flight drag equal thrust, and lift  equal weight (almost)

  

 Jan

 [quote]   ---

- The Matronics Kitfox-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Kitfox-List

Display posts from previous:

	Matronics Email Lists Forum Index -> Kitfox-List	All times are GMT - 8 Hours Goto page Previous 1, 2
Page 2 of 2

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum