Matronics Email Lists :: View topic - Air foil for cable...

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

Air foil for cable...

Matronics Email Lists Forum Index -> Kolb-List

View previous topic :: View next topic

Author Message

nickc(at)mtaonline.net
Guest

Posted: Tue Jan 11, 2011 11:36 pm Post subject: Air foil for cable...

Kolber’s,

 

A year or two ago someone posted drag values for parts of a Kolb, if I remember right. I was amazed at the drag values for the cables on the tail.

 

One of you, with a lot more skill than me, can probable come up with an airfoil for a cable! 

 

Winter is not over yet, what do you think?

 

Thanks as all ways for all your knowledge!

 

Nick Cassara

Palmer, Alaska

 

Kolbra #1

 

  [quote][b]

GeoB

Joined: 16 Jun 2009
Posts: 207
Location: Fresno, CA

Posted: Wed Jan 12, 2011 12:55 am Post subject: Air foil for cable...

 	  Quote: 	
		   I was amazed at the drag values for the cables on the tail.


	


I would like to see the drag values too.



I have been thinking about this issue- now, I am not any kind of aircraft guru, completely new to aircraft- so I am just 'seeding' the discussion with an idea.



Have you ever used Shoo-goo? Great stuff. Much stronger and tougher than silicone seal, yet comes in a squeeze tube.



I wish the feller in the lab coat in the video had demonstrated the drag of a tube faired on only one side, because that is what I am thinking- run a bead of shoo-goo down a cable, shape it into a 'V' between your fingers somehow.



A Kolber posted pics somewhere showing aluminum v-shaped fairings he had a sheet metal shop brake for him. They were rivited to the sides, forming a trailing edge streamlined shape. Don't know how effective they are (he had no test data either) but it gave me the idea on the cable streamlining.

_________________
GeoB

"Members of Congress should be compelled to wear uniforms like NASCAR drivers, so we could identify their corporate sponsors"

pj.ladd(at)btinternet.com
Guest

Posted: Wed Jan 12, 2011 2:54 am Post subject: Air foil for cable...

With all the current excitement about cutting drag  it occurs to me that most of the examples shown have been for much higher speeds  that the ones we generally fly at.

  

 I forget the maths now but doesn`t drag increase at  the square of the speed or something like that?

  

 Streamling lift struts etc might be worth it, and  it looks nice, but is it worth it for cables at speeds of 50 to 70?

  

 WW1 biplanes used tear drop shaped cables certainly  but they were operating at around 100mph and few of us reach that and live to  tell the tale.

  

 Just a thought

  

 Pat

   [quote][b]

elleryweld(at)aol.com
Guest

Posted: Wed Jan 12, 2011 4:46 am Post subject: Air foil for cable...

--

elleryweld(at)aol.com
Guest

Posted: Wed Jan 12, 2011 4:46 am Post subject: Air foil for cable...

would it reduce drag on a cable if you was to fold a peice of vinal tape in half to leave a 3/4 inch trailing edge?  let the testing begin 

--

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Jan 12, 2011 4:58 am Post subject: Air foil for cable...

At 02:26 AM 1/12/2011, Nick Cassara wrote:



  	  Quote: 	
		  One of you, with a lot more skill than me, can probable come up with an airfoil for a cable! 	


 Streamlined wires have long been used in aircraft.  There are a couple of companies that still make them today.  They're solid wire, rolled to the streamline shape, then threads have to be formed at the ends... they're special order, of course, made to the specific length you need... and expensive.



 Years ago, in U-control (control line) model airplane racing (these models can go 200+ mph, on 60' cables of around .015 diameter), somebody figured out that the lines were 80% or more of the drag, and came up with what was termed "funny lines"... basically a streamlined enclosure to hold the two lines close together, one behind the other.  The original was a thin wall tube slipped over the front wire, and a bit of tap wrapped around and stuck to itself forming a tab in back, forming a crude airfoil shape.  The rear wire ran through the gap in the tape immediately behind the tube.  Later, molded plastic shapes were used.  IIRC, they cleaned up in the speed events at the Nationals that year... and funny lines were promptly banned immediately afterwards.



 -Dana

 --

 Beam me up, Scotty, it ate my phaser.

    [quote][b]

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Wed Jan 12, 2011 7:32 am Post subject: Re: Air foil for cable...

This is overexposed, but you get the idea: OD 5/16" X 5/32" X 35", ID 1/8" X 1/4". Got it at the local RC hobby shop, thinwall aluminum, weight 1/2 oz. Ought to be able to slip a tail brace wire through it during cable assembly, Goop it to an end fitting to keep it from pivoting. Use 2 pieces, each one attached at an end fitting, leave the middle of the wire uncovered so you could still fold the tail? Maybe squeeze it thinner so that it has less cross section?



Food for thought...



Richard Pike

MKIII N420P (420ldPoops)

SL.JPG

Description:

Filesize:

35.93 KB

Viewed:

3746 Time(s)

radiobluebook(at)gmail.co
Guest

Posted: Wed Jan 12, 2011 8:26 am Post subject: Air foil for cable...

Regarding drag; this is an interesting video that has been circulating on other groups. 

  

 http://www.youtube.com/watch?v=ftq8jTQ8ANE



 

 On Wed, Jan 12, 2011 at 2:53 AM, George Bearden <gab16(at)sbcglobal.net (gab16(at)sbcglobal.net)> wrote:

 [quote]--> Kolb-List message posted by: George Bearden <gab16(at)sbcglobal.net (gab16(at)sbcglobal.net)>

 

 	  Quote: 	
		   I was amazed at the drag values for the cables on the tail.


	


I would like to see the drag values too.



I have been thinking about this issue- now, I am not any kind of aircraft guru, completely new to aircraft- so I am just 'seeding' the discussion with an idea.

 

Have you ever used Shoo-goo? Great stuff. Much stronger and tougher than silicone seal, yet comes in a squeeze tube.



I wish the feller in the lab coat in the video had demonstrated the drag of a tube faired on only one side, because that is what I am thinking- run a bead of shoo-goo down a cable, shape it into a 'V' between your fingers somehow.

 

A Kolber posted pics somewhere showing aluminum v-shaped fairings he had a sheet metal shop brake for him. They were rivited to the sides, forming a trailing edge streamlined shape. Don't know how effective they are (he had no test data either) but it gave me the idea on the cable streamlining.

 n,

 www.matronics.com/Navigator?Kolb-List" target="_blank">http://www.matronics.com/Navigator?Kolb-List

 ronics.com/" target="_blank">http://forums.matronics.com

 Matt Dralle, List Admin.

 =====



[b]

Rex Rodebush

Joined: 10 Jan 2006
Posts: 209
Location: Branson West area, Missouri

Posted: Wed Jan 12, 2011 9:48 am Post subject: Re: Air foil for cable...

The experiment we saw on the video and many others are explained in the book "Shape and Flow, the Fluid Dynamics of Drag" by Ascher H. Shapiro, published by Doubleday Anchor.  It's out of print but I got a copy via the internet.



Rex

mdnanwelch7(at)hotmail.co
Guest

Posted: Wed Jan 12, 2011 9:57 am Post subject: Air foil for cable...

> would it reduce drag on a cable if you was to fold a peice of vinal tape in half to leave a 3/4 inch trailing edge? let the testing begin 

 	  Quote: 	
		  Ellery

  
	


 Ellery,

  

   Yes, I bet it would....a lot.  

  

   What about this idea?  I have a roll of heavy thickness aluminum tape, the 

 kind air conditioning installers use (that's who I go it from!!).  It has a protective

 tape on it.

   What if we cut the tape to length, then bent it lengthwise, down the middle?

 Then we pulled off the protective tape.  Next, carefully (!!) stick a length of 

 nylon string exactly down the center on the crease-line (this to hold the aluminum

 tape back a bit from the blunt edge, sort of trying to maintain the airfoil shape).

  

   Now, with the cable good & tight, try to accurately adhere the tape onto one

 edge of cable.  Once you have the orientation accurate, begin pinching the two 

 sides of the tape.

   It may take a couple of practice runs, but I bet a guy could make a really good

 looking aluminum tape cable airfoils.

  

 Mike Welch

 		 	   		    [quote][b]

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Jan 12, 2011 10:23 am Post subject: Air foil for cable...

It may take a couple of practice runs, but I bet a guy could make a 

really good

looking aluminum tape cable airfoils.



Mike Welch

How much drag reduction to you expect to receive from streamlining 8 to 10 

feet of 3/32" cable?



Doubt you or your Kolb would ever notice the difference.



The following does not pertain to cable air foils, but it does have 

something to do with reducing drag and improving air flow to the prop on a 

MKIII.



The first modification we made to my MKIII fuselage was replace the 7/16" or 

1/2" round 4130 tubes with streamlined 4130 tubes at the rear of the 

fuselage that brace the lower side of the rear engine mount.  Don't know how 

much good that did, but was bound to make some improvement removing that 

drag and air turbulence right before it was fed into the cleanest part of 

the prop arch.



Another thing we did that reduced drag was the main landing gear legs.  Only 

18" of .125" gear leg are exposed to the air stream.



Permanently enclosing the upper rear of the fuselage also reduced drag, as 

did the keel faring on the bottom of the fuselage.  The keel faring also 

cleaned up air going to the prop.



Still the quickest MKIII until someone comes along that can out run me, side 

by side.



Last race I had was at the Kolb Homecoming a couple years back with Steven 

Green and his MKIII powered with a 912ULS.  I beat hands down.  



If only I could have out run John Williamson and his 912ULS powered Kolbra. 

John was 10 mph quicker than Miss P'fer.  Skinny Kolbs are faster than fat 

ones.



john h

mkIII

Titus, Alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Display posts from previous:

	Matronics Email Lists Forum Index -> Kolb-List	All times are GMT - 8 Hours
Page 1 of 1

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