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jindoguy(at)gmail.com
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 Posted: Wed Jan 16, 2008 6:20 am Post subject: Streamlining struts |
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I've published this method before, but the conversation is current again so I'll reprise. My friend Ralph Senter invented this back in the day when hang gliders had spars exposed to the wind.
Get a piece of .015 to .020 Mylar sheet 6 times as wide as the circumference of the strut you wish to streamline and long enough to go end to end. Fold in half on the short dimension, crease lightly and stick it together with double sided sail makers seam tape. Sew along the long edge. Ralph used a zig zag stitch so the stress was spread out better than a straight stitch. Slip this sleeve over your strut and it's streamlined. No structural issues and far cheaper than buying new metal.
Sheet mylar can be had from blueprint reproduction business's or found on the web.
Rick Girard
[quote][b]
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slyck(at)frontiernet.net
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| Posted: Wed Jan 16, 2008 9:19 am Post subject: Streamlining struts |
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I recently bought a replacement roof panel for a shed because of wind damage.The old one was the corrugated translucent fiberglass. The new one is polycarbonate.
If you could find a piece of that in flat sheet it is extremely tough and flexible.
-just thinking out loud.
BB
On 16, Jan 2008, at 9:18 AM, Richard Girard wrote:
[quote]I've published this method before, but the conversation is current again so I'll reprise. My friend Ralph Senter invented this back in the day when hang gliders had spars exposed to the wind.
Get a piece of .015 to .020 Mylar sheet 6 times as wide as the circumference of the strut you wish to streamline and long enough to go end to end. Fold in half on the short dimension, crease lightly and stick it together with double sided sail makers seam tape. Sew along the long edge. Ralph used a zig zag stitch so the stress was spread out better than a straight stitch. Slip this sleeve over your strut and it's streamlined. No structural issues and far cheaper than buying new metal.
Sheet mylar can be had from blueprint reproduction business's or found on the web.
Rick Girard
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1planeguy(at)kilocharlie.
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| Posted: Wed Jan 16, 2008 10:11 am Post subject: Streamlining struts |
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<snip>
The new one is polycarbonate.
If you could find a piece of that in flat sheet it is extremely tough and flexible.
-just thinking out loud.
BB
<snip>
polycarbonate is the generic name for LEXAN…same as your windshield…
Jeremy Casey
[quote][b]
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R. Hankins
Joined: 18 Jan 2006
Posts: 185
Location: Grants Pass, Oregon
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| Posted: Thu Jan 17, 2008 11:06 am Post subject: Re: Streamlining struts |
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Rick,
Do I have this correct? For a 1 inch tube:
Circumference = 3.14"
6 * 3.14 = 18.8" wide
I tried this with paper to see what it looks like and it just seems like a lot of material for a 1" tube.
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Roger in Oregon
1992 KXP 503 - N1782C |
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mdnanwelch7(at)hotmail.co
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| Posted: Thu Jan 17, 2008 11:27 am Post subject: Streamlining struts |
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Roger,
I don't mean to interupt your conversation with Rick, but the formula for circumference is;
3.14 X Diameter (usually referred to as: pi*D) If you are talking about a 1" tube, then the circumference is 3.14 X 1" = 3.14".
Mike Welch
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Shed those extra pounds with MSN and The Biggest Loser!!
http://biggestloser.msn.com/
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R. Hankins
Joined: 18 Jan 2006
Posts: 185
Location: Grants Pass, Oregon
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| Posted: Thu Jan 17, 2008 11:55 am Post subject: Re: Streamlining struts |
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Mike:
The original formula given by Rick was:
Circumference * 6
Which for a 1" tube becomes 3.14 x 6.
Which equals 18.8"
Which seems like a lot of material for a one inch tube when you try it.
do not archive
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Roger in Oregon
1992 KXP 503 - N1782C |
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slyck(at)frontiernet.net
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| Posted: Thu Jan 17, 2008 11:58 am Post subject: Streamlining struts |
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pi are not square... pi are round
BB
do not archive
On 17, Jan 2008, at 2:24 PM, Mike Welch wrote:
| Quote: |
Roger,
I don't mean to interupt your conversation with Rick, but the
formula for circumference is;
3.14 X Diameter (usually referred to as: pi*D) If you are talking
about a 1" tube, then the circumference is 3.14 X 1" = 3.14".
Mike Welch
> Subject: Re: Streamlining struts
> From: rphanks(at)grantspass.com
> Date: Thu, 17 Jan 2008 11:06:00 -0800
> To: kolb-list(at)matronics.com
>
>
>
> Rick,
> Do I have this correct? For a 1 inch tube:
> Circumference = 3.14"
> 6 * 3.14 = 18.8" wide
>
> I tried this with paper to see what it looks like and it just
> seems like a lot of material for a 1" tube.
>
> --------
> Roger in Oregon
> 1992 KXP 503 - N1782C
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=158836#158836
>
>
_________________________________________________________________
Shed those extra pounds with MSN and The Biggest Loser!!
http://biggestloser.msn.com/
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jindoguy(at)gmail.com
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| Posted: Thu Jan 17, 2008 1:06 pm Post subject: Streamlining struts |
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Roger, mike, et al. Got my wording wrong, sorry. Should be 6 times as wide as diameter, not circumference. Hoerner in "Fluid Dynamic Drag" found that the ideal shape for streamlining a body was an ellipse 3 times as long as it was in diameter. If you figure 1/2" for the seam, then add 1" to the total width.
So for a 1 1/2" diameter strut, you'd need a piece of mylar 10" wide.
Rick
On Jan 17, 2008 1:55 PM, R. Hankins <rphanks(at)grantspass.com (rphanks(at)grantspass.com)> wrote:
[quote]--> Kolb-List message posted by: "R. Hankins" < rphanks(at)grantspass.com (rphanks(at)grantspass.com)>
Mike:
The original formula given by Rick was:
Circumference * 6
Which for a 1" tube becomes 3.14 x 6.
Which equals 18.8"
Which seems like a lot of material for a one inch tube when you try it.
do not archive
--------
Roger in Oregon
1992 KXP 503 - N1782C
Read this topic online here:
[quote][b]
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beauford173(at)verizon.ne
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| Posted: Thu Jan 17, 2008 2:05 pm Post subject: Streamlining struts |
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..yeah...and DEEP, too....
beauford
do not archive
---
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mdnanwelch7(at)hotmail.co
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| Posted: Thu Jan 17, 2008 3:29 pm Post subject: Streamlining struts |
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Rick,
et al?? et al!!!? We're just simple folks here. Just say "You'ze guys!!"
Chuckling... Mike Welch
Do not archive
________________________________
Date: Thu, 17 Jan 2008 15:00:57 -0600
From: jindoguy(at)gmail.com
To: kolb-list(at)matronics.com
Subject: Re: Re: Streamlining struts
Roger, mike, et al. Got my wording wrong, sorry. Should be 6 times as wide as diameter, not circumference. Hoerner in "Fluid Dynamic Drag" found that the ideal shape for streamlining a body was an ellipse 3 times as long as it was in diameter. If you figure 1/2" for the seam, then add 1" to the total width.
So for a 1 1/2" diameter strut, you'd need a piece of mylar 10" wide.
Rick
On Jan 17, 2008 1:55 PM, R. Hankins > wrote:
Mike:
The original formula given by Rick was:
Circumference * 6
Which for a 1" tube becomes 3.14 x 6.
Which equals 18.8"
Which seems like a lot of material for a one inch tube when you try it.
do not archive
--------
Roger in Oregon
1992 KXP 503 - N1782C
Read this topic online here:
_________________________________________________________________
Helping your favorite cause is as easy as instant messaging. You IM, we give.
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jindoguy(at)gmail.com
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| Posted: Thu Jan 17, 2008 4:44 pm Post subject: Streamlining struts |
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Mike, Just trying to be polite. My Grandma, God rest her soul, always told me it doesn't cost a thing to be polite. But it's You'ze guys from now on. 
Rick
On Jan 17, 2008 5:26 PM, Mike Welch < mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
[quote]--> Kolb-List message posted by: Mike Welch < mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)>
Rick,
et al?? et al!!!? We're just simple folks here. Just say "You'ze guys!!"
Chuckling... Mike Welch
Do not archive
________________________________
Date: Thu, 17 Jan 2008 15:00:57 -0600
From: jindoguy(at)gmail.com (jindoguy(at)gmail.com)
To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)
Subject: Re: Re: Streamlining struts
Roger, mike, et al. Got my wording wrong, sorry. Should be 6 times as wide as diameter, not circumference. Hoerner in "Fluid Dynamic Drag" found that the ideal shape for streamlining a body was an ellipse 3 times as long as it was in diameter. If you figure 1/2" for the seam, then add 1" to the total width.
So for a 1 1/2" diameter strut, you'd need a piece of mylar 10" wide.
Rick
On Jan 17, 2008 1:55 PM, R. Hankins > wrote:
--> Kolb-List message posted by: "R. Hankins" < rphanks(at)grantspass.com (rphanks(at)grantspass.com)>
Mike:
The original formula given by Rick was:
Circumference * 6
Which for a 1" tube becomes 3.14 x 6.
Which equals 18.8"
Which seems like a lot of material for a one inch tube when you try it.
do not archive
--------
Roger in Oregon
1992 KXP 503 - N1782C
Read this topic online here:
[quote][b]
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pj.ladd(at)btinternet.com
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Thom Riddle
Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)
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| Posted: Fri Jan 18, 2008 11:26 am Post subject: Streamlining struts |
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Roger,
You reach a point of rapidly diminishing returns (streamline effect)
if the ratio of the airfoil length (fore to aft) to tube diameter
(airfoil thickness) goes past about 4 to 1. So for a tube diameter of
1" the airfoil material need not be more than about 8" (4 x 2) plus an
inch for deviation from straight line, or about 9" should do it for
each airfoil section.
Thom in Buffalo
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_________________
Thom Riddle
Buffalo, NY (9G0)
Don't worry about old age... it doesn't last very long.
- Anonymous |
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R. Hankins
Joined: 18 Jan 2006
Posts: 185
Location: Grants Pass, Oregon
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| Posted: Sat Jan 19, 2008 12:11 am Post subject: Re: Streamlining struts |
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Thom,
That agrees with what I came up with using a piece of newspaper, some scotch tape and a one inch tube. I left my copy of "Aerodynamics for Engineers" on the shelf, along with my Mark's handbook for Mechanical Engineers. Sometimes a 20-20 eyeball will get you close enough. I assumed that rick had substituted circumference for diameter and tried a six inch wrap, but it looked too short. I then cut one so that it "looked" about right and came out with 8 1/2 inches.
I would like to try applying streamlining to all of my exposed tubing this spring sometime and report the results to the list. I don't expect a huge difference, but I should see some. I'll do the same thing with VG's one of these days.
Hoping for sunshine.......
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Roger in Oregon
1992 KXP 503 - N1782C |
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planecrazzzy
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| Posted: Sat Jan 19, 2008 3:42 pm Post subject: Re: Streamlining struts |
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I made these Stream line sleeves....
I found a 18" piece of alum cheap....
Sheared it in half....
"Rolled" each 9" piece....24" Radius ???
Used a Break to bend them in the middle ( Knife blade )
Welded the seam....
Tight fit over my Lift struts....
Used 3 bolts on top ( Other bolts are 90 degrees )
They stopped my Lift Struts from vibrating in flight....
Gotta Fly...
Mike & "Jaz" in MN
.
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JetPilot
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Stopping the vibrations is reason enough to do that, did you get any speed gain with the stream line sleeves ?