Today's Message Index:
----------------------
1. 12:15 AM - Re: Kolb-List Digest: 7 Msgs - 03/11/14 (George Bearden)
2. 02:42 AM - Re: Re: Drag Reduction Paradox (Robert Gillisse)
3. 04:49 AM - Re: Re: Drag Reduction Paradox (Pat Ladd)
4. 06:58 AM - Re: Re: Drag Reduction Paradox (Mike)
5. 07:31 AM - Re: Re: Kolb-List Digest: 7 Msgs - 03/11/14 (Charlie England)
6. 07:59 AM - Re: Re: Kolb-List Digest: 7 Msgs - 03/11/14 (Jack B. Hart)
7. 08:37 AM - Re: Re: Drag Reduction Paradox (Richard Girard)
8. 11:41 AM - Re: Re: Drag Reduction Paradox (Robert Gillisse)
9. 12:49 PM - Re: Re: Drag Reduction Paradox (Rick Neilsen)
10. 03:43 PM - Re: Drag Reduction Paradox (Larlaeb)
11. 05:20 PM - Re: Re: Drag Reduction Paradox (John Hauck)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | RE: Kolb-List Digest: 7 Msgs - 03/11/14 |
> showing the equivalent cross sections of a wire, a square rod
Saw that video. Convinced me.
> Note carefully the decimal point locations.
Umm.. on what diagram? "Streamline That Tubing"?
Do you know of a good source for the construction details other than buying
another complete book? As I looked at the diagram I felt it was missing the
dimension that locates the widest part of the streamline. Plus, I wasn't
sure what it means with the "4X Tubing O.D." Couldn't figger out fer sure
what it meant. Not the circumference is it? Seems that would be a useless
bit of info. Have any one of us built these? I have some dacron, thinking
about covering foam with dacron and paint maybe.
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Drag Reduction Paradox |
Ref> Vortex Generators (VG's)... just installed them on my Firestar (43 on
each wing) and the first thing I noticed was increased climb rate and bette
r control at low-speed touchdowns (lowered stall speed combined with better
handling is a win-win). Don't know about an increase in cruise speed, just
learned that drag is not a factor at higher speeds. =0A=0ARobert Gillisse
=0A2004 Kolb Firestar II=0A503 DCDI=0ACollegedale, TN=0A=0A=0A=0AOn Thursda
y, March 13, 2014 12:44 AM, Richard Pike <richard@bcchapel.org> wrote:=0A
=0A=0A=0Asmlplanet(at)msn.com wrote:=0A> I haven't noticed any one saying a
ny thing about vortex generators to help performance. I have a Mark 111 / 9
12=EF=BD 80hp with the enclosed rear area, fairing on the struts, steel
landing gear with tundra tires.=EF=BD After installing the vortex genera
tors I noticed a lower stall speed, increase in cruising speed and climb. T
here was also a decrease in fuel usage both solo and duel.=EF=BD My main
reason for installing them was the short field and beach landing and take
off...less roll out and was surprised by the above added advantages. =0A>
=0A=0A=0AYep. My experience exactly. Isn't it wonderfully simple and straig
htforward?=0A=0AEnjoy.=0A=0A--------=0ARichard Pike=0AKolb MKIII N420P (420
ldPoops)=0AKingsport, TN 3TN0=0AMy soul shall be joyful in the LORD; It sha
ll rejoice in His salvation. Psalm 35:9=0A=0A=0A=0A=0ARead this topic onlin
e here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=420251#420251=0A
=========================0A
===================
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Drag Reduction Paradox |
<<just learned that drag is not a factor at higher speeds. >>
Huh!,
I thought drag increased by the square of the speed (or something like
that) In essence the faster you go the MORE drag you create..
Pat
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Drag Reduction Paradox |
Pat=2C So did I=2C Pat.
I'm not trying to speak completely on behalf of Robert (who said "just le
arned that drag is not a factor at higher speeds" )=2C but what I "think" h
e meant was=2C (since he said something we all know is wrong)=2C "in re
gards to the addition of VGs and their affect on the top end of "my" plane'
s speed ranges=3B "I just learned that drag (of only the VGs) is not a fac
tor at higher speeds".
Yeah=2C took me reading what he said about three or four times before I f
igured out what he "may" have meant.
If I'm incorrect=2C and he meant precisely what he said=2C well..........
...maybe he will explain what I missed=2C too.
Mike Welchdo not archive
From: pj.ladd@btinternet.com
Subject: Re: Kolb-List: Re: Drag Reduction Paradox
=0A
=0A
=0A
=0A
=0A
=0A
=0A
<<just learned that drag is not a factor at higher speeds. =0A
>>=0A
=0A
Huh!=2C=0A
I thought drag increased by the square of the speed =0A
(or something like that) In essence the faster you go the MORE drag you
=0A
create..=0A
=0A
Pat=0A
=0A
=0A
=0A
=0A
=0A
============0A
============0A
============0A
============0A
=0A
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: RE: Kolb-List Digest: 7 Msgs - 03/11/14 |
On 3/13/2014 2:15 AM, George Bearden wrote:
>
>> showing the equivalent cross sections of a wire, a square rod
> Saw that video. Convinced me.
>
>> Note carefully the decimal point locations.
> Umm.. on what diagram? "Streamline That Tubing"?
>
> Do you know of a good source for the construction details other than buying
> another complete book? As I looked at the diagram I felt it was missing the
> dimension that locates the widest part of the streamline. Plus, I wasn't
> sure what it means with the "4X Tubing O.D." Couldn't figger out fer sure
> what it meant. Not the circumference is it? Seems that would be a useless
> bit of info. Have any one of us built these? I have some dacron, thinking
> about covering foam with dacron and paint maybe.
For the decimal point reference: in the table in that article: 0.085 for
streamline vs 1.03 for round. Streamline has less than 1/10th the drag
of a round tube. Also interesting to note that a round tube has *higher
drag* than a square tube (which would be 1.00, the reference).
I agree, the '4x tube OD' in the drawing is rather vague. I think he's
saying that the length of the streamline is 3x tube OD, the max width of
the streamline is 1.07x tube OD, and the length around the curve of the
streamline is 4x the tube OD. I can only assume that he's trying to give
some rough specs for 'rolling your own', without the required (rather
convoluted, for non- mathematician) calculations.
Don't some of the ultralite suppliers sell plastic streamline tubing
that just snaps around round tube?
Charlie
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: RE: Kolb-List Digest: 7 Msgs - 03/11/14 |
At 12:15 AM 3/13/2014 -0700, you wrote:
>
>Do you know of a good source for the construction details other than buying
>another complete book? As I looked at the diagram I felt it was missing the
>dimension that locates the widest part of the streamline. Plus, I wasn't
>sure what it means with the "4X Tubing O.D." Couldn't figger out fer sure
>what it meant. Not the circumference is it? Seems that would be a useless
>bit of info. Have any one of us built these? I have some dacron, thinking
>about covering foam with dacron and paint maybe.
>
>
How I made trailing edge and strut fairings:
http://www.jackbhart.com/firefly/firefly105.html
http://www.jackbhart.com/firefly/firefly91.html
Jack B. Hart FF004
Winchester, IN
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Drag Reduction Paradox |
From: http://en.wikipedia.org/wiki/Drag_equation
[image: F_D\, =\, \tfrac12\, \rho\, v^2\, C_D\, A]
where
*FD* is the drag force <http://en.wikipedia.org/wiki/Drag_force>, which is
by definition the force component in the direction of the flow
velocity,[1]<http://en.wikipedia.org/wiki/Drag_equation#cite_note-1>
*=F1* is the mass density <http://en.wikipedia.org/wiki/Mass_density> of th
e
fluid, [2] <http://en.wikipedia.org/wiki/Drag_equation#cite_note-2>*v* is
the velocity <http://en.wikipedia.org/wiki/Velocity> of the object relative
to the fluid,*A* is the reference area <http://en.wikipedia.org/wiki/Area>,
and*CD* is the drag
coefficient<http://en.wikipedia.org/wiki/Drag_coefficient> -
a dimensionless <http://en.wikipedia.org/wiki/Dimensionless_number>
coefficient <http://en.wikipedia.org/wiki/Coefficient> related to the
object's geometry and taking into account both skin
friction<http://en.wikipedia.org/wiki/Skin_friction>
and form drag <http://en.wikipedia.org/wiki/Form_drag>.
It's that V squared that increases the drag with velocity; i.e. go twice as
fast and you produce 4 times the drag.
Rick Girard
On Thu, Mar 13, 2014 at 8:57 AM, Mike <mdnanwelch7@hotmail.com> wrote:
> Pat,
> So did I, Pat.
>
> I'm not trying to speak completely on behalf of Robert (who said "just
> learned that drag is not a factor at higher speeds" ), but what I "think"
> he meant was, (since he said something we all know is wrong),
> "in regards to the *addition* of VGs and their affect on the top end
> of "my" plane's speed ranges; "I just learned that drag (of only the
> VGs) is not a factor at higher speeds".
>
> Yeah, took me reading what he said about three or four times before I
> figured out what he "may" have meant.
>
> If I'm incorrect, and he meant precisely what he said,
> well.............maybe he will explain what I missed, too.
>
> Mike Welch
> do not archive
>
>
> ------------------------------
> From: pj.ladd@btinternet.com
> To: kolb-list@matronics.com
> Subject: Re: Kolb-List: Re: Drag Reduction Paradox
> Date: Thu, 13 Mar 2014 04:49:05 -0700
>
>
> <<just learned that drag is not a factor at higher speeds. >>
>
> Huh!,
> I thought drag increased by the square of the speed (or something like
> that) In essence the faster you go the MORE drag you create..
>
> Pat
>
> *
>
> ==========
> arget="_blank">http://www.matronics.com/Navigator?Kolb-List <http://www
.matronics.com/Navigator?Kolb-List>
> ==========
> http://forums.matronics.com <http://forums.matronics.com>
> ==========
> ="_blank">http://www.matronics.com/contribution <http://www.matronics.c
om/contribution>
> ==========
>
> *
>
> *
>
===========
onics.com/Navigator?Kolb-List>
===========
===========
om/contribution>
===========
>
> *
>
>
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Drag Reduction Paradox |
You are right, Mike...in the CONTEXT of what I was writing,=0Anaturally I w
as referring to the associated drag factor of the VG's... not drag=0AIN GEN
ERAL. That would make me look stupid if I said that. Do you see that Pat?
=0ADiscussion... How Much Drag would those 1/2 inch high, slightly angled V
G's produce=0Aat a position 'about' 10" behind the leading edge with the wi
ng at an=0Aangle of attack commensurate with , say, 65 MPH?? I believe ther
e would be a=0Avacuum there. Hmm. Where (and when) does the air separate?
=0A=0A=0A=0AOn Thursday, March 13, 2014 10:05 AM, Mike <mdnanwelch7@hotmail
.com> wrote:=0A =0A =0APat,=0A- So did I, Pat. -=0A=0A- I'm not tryi
ng to speak completely on behalf of Robert (who said "just learned that dra
g is not a factor at higher speeds" ), but what I "think" he meant was, (si
nce he said something we all know is wrong),-=0A- - "in regards to th
e addition-of VGs and their affect on the top end of "my" plane's speed
-ranges; -"I just learned that drag (of only the VGs) is not a factor a
t higher speeds".=0A=0A- Yeah, took me reading what he said about three o
r four times before I figured out what he "may" have meant.=0A=0A- If I'm
incorrect, and he meant precisely what he said, well.............maybe he
will explain what I missed, too.=0A=0AMike Welch=0Ado not archive=0A=0A=0A
=0A________________________________=0AFrom: pj.ladd@btinternet.com=0ATo: ko
lb-list@matronics.com=0ASubject: Re: Kolb-List: Re: Drag Reduction Paradox
=0ADate: Thu, 13 Mar 2014 04:49:05 -0700=0A=0A =0A<<just learned that drag
is not a factor at higher speeds. =0A>> =0A=0AHuh!, =0AI thought drag incre
ased by the square of the speed =0A(or something like that)- In essence t
he faster you go the MORE drag you =0Acreate.. =0A- =0APat =0A =0A==
==========0Aarget="_blank">http://www.matronics.com/Nav
igator?Kolb-List=0A============0Ahttp://forums.matron
ics.com=0A============0A="_blank">http://www.matron
=========
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Drag Reduction Paradox |
I asked the question of drag from VG at a drag reduction form at Oshkosh a
few years ago. The response was that VGs when properly used clean up
aerodynamic issues to the point that they don't increase drag at speed and
sometimes even decrease drag.
Rick Neilsen
Redrive VW Powered MKIIIC
On Thu, Mar 13, 2014 at 2:37 PM, Robert Gillisse <
thermal_hunter2002@yahoo.com> wrote:
> You are right, Mike...in the CONTEXT of what I was writing, naturally I
> was referring to the associated drag factor of the VG's... not drag IN
> GENERAL. That would make me look stupid if I said that. Do you see that
> Pat? Discussion... How Much Drag would those 1/2 inch high, slightly angled
> VG's produce at a position 'about' 10" behind the leading edge with the
> wing at an angle of attack commensurate with , say, 65 MPH?? I believe
> there would be a vacuum there. Hmm. Where (and when) does the air separate?
>
>
> On Thursday, March 13, 2014 10:05 AM, Mike <mdnanwelch7@hotmail.com>
> wrote:
> Pat,
> So did I, Pat.
>
> I'm not trying to speak completely on behalf of Robert (who said "just
> learned that drag is not a factor at higher speeds" ), but what I "think"
> he meant was, (since he said something we all know is wrong),
> "in regards to the *addition* of VGs and their affect on the top end
> of "my" plane's speed ranges; "I just learned that drag (of only the
> VGs) is not a factor at higher speeds".
>
> Yeah, took me reading what he said about three or four times before I
> figured out what he "may" have meant.
>
> If I'm incorrect, and he meant precisely what he said,
> well.............maybe he will explain what I missed, too.
>
> Mike Welch
> do not archive
>
>
> From: pj.ladd@btinternet.com
> To: kolb-list@matronics.com
> Subject: Re: Kolb-List: Re: Drag Reduction Paradox
> Date: Thu, 13 Mar 2014 04:49:05 -0700
>
> <<just learned that drag is not a factor at higher speeds. >>
>
> Huh!,
> I thought drag increased by the square of the speed (or something like
> that) In essence the faster you go the MORE drag you create..
>
> Pat
>
> *
>
> ==========
> arget="_blank">http://www.matronics.com/Navigator?Kolb-List <http://www.matronics.com/Navigator?Kolb-List>
> ==========
> http://forums.matronics.com <http://forums.matronics.com>
> ==========
> ="_blank">http://www.matronics.com/contribution <http://www.matronics.com/contribution>
> ==========
>
> *
>
> *http://www.matronics.c <http://www.matronics.c>=================
>
> *
>
>
> *
>
>
> *
>
>
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Drag Reduction Paradox |
I think most of the advantages of any streamlining you do are going to be more
in the area of efficiencies at lower speed (same speed with less power, better
fuel consumption etc.) than a much greater top speed. This is because drag increases
with speed exponentially as has already been stated and the improvement
you have made in the form drag by streamlining is pretty quickly overcome by
induced drag. I think the wing form of a Kolb is roughly optimized in size
and shape for somewhere in the 100 mph range and pushing that big high lift wing
will begin to take an unreasonable amount of power at some point even if substantially
eliminate a lot of the pod form drag. I'm not saying you won't go
faster, but the speed returns will rapidly diminish. Probably stating the obvious
but there's my 1.5 cents.
Allan
:D
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=420304#420304
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Drag Reduction Paradox |
Wonder how that relates to a Kolb? and what is "at speed" for a Kolb?
Most of the feedback I get from Kolb owners that install VGs is a slight
reduction in top speed. Don't know about cruise speed. Not much difference
between cruise speed for me, when I am flying Kolbs, and top speed.
Top speed in a Kolb in normally never comfortable. They were not designed
for speed.
I have a normal "sweet spot" cruise speed, and a "get to the next way point
a little quicker" cruise speed.
In my MKIII, anything over 90 mph starts to get uncomfortable and is wasting
a lot of fuel. Normal cruise, 5,000 rpm, 912ULS, is 80 to 85. High cruise,
5,200 rpm 912ULS, is 85 to 90, depended on I am loaded.
If your Kolb is getting a speed boost with VGs, I am happy for you.
john h
mkIII
Titus, Alabama
I asked the question of drag from VG at a drag reduction form at Oshkosh a
few years ago. The response was that VGs when properly used clean up
aerodynamic issues to the point that they don't increase drag at speed and
sometimes even decrease drag.
Rick Neilsen
Redrive VW Powered MKIIIC
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|