Today's Message Index:
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1. 07:43 AM - Re: Drag reduction (KIRBY, DENNIS T GS-13 USAF AFMC AFNWC/ENS)
2. 08:08 AM - Re: Re: Drag reduction (b young)
3. 08:28 AM - reduced drag and speed. (b young)
4. 09:03 AM - Re: reduced drag and speed. (John Hauck)
5. 12:00 PM - Re: Re: Drag Reduction Paradox (Jack B. Hart)
6. 12:04 PM - Re: Drag Reduction Paradox (Arizona Flyer)
7. 12:25 PM - Re: Re: Drag Reduction Paradox (Sky Biker)
8. 09:39 PM - Re: Drag Reduction Paradox (Richard Pike)
Message 1
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| Subject: | Re: Drag reduction |
Hauck wrote: << Loose fabric makes a lot different airfoil than tight fabric.
As tight as the fabric is on my wing, I still get a concave lower wing surface
in flight - The more concave that surface, the slower the airplane will fly,
but probably kill a lot of top and cruise speed. >>
?! I did not know this! Will hafta check it out the underside of my wing, next
time I fly.
Rick Girard wrote: << Pareto Principle? To generalize, we could say that 80% of
the drag of a Kolb is caused by 20% of the drag producers. >>
Rick is correct - I have also seen it written (by Barnaby Wainfan, in one of his
Kitplanes columns) that to reduce drag, the most benefit will come from tackling
the biggies first: Streamline any struts in the airflow (like wing struts
and landing gear legs), use gap seals for all the moving control surfaces, close
up any open areas on the fuselage (Kolbs pods are notorious for this), and
try to avoid sharp bends along the path of the airflow. On my Mark-3, this happens
as air flows past the aft edges of the doors - it's a pretty sharp corner
for the air to flow around.
My stock Mark-3 had open sides on the upper-rear area of the pod. I covered this
area with Lexan sheet, and that helped. Hauck was right about the windshield-to-wing
junction being a source of stagnation - lots of drag there. I made
an aluminum fairing to smooth the airflow at that area. That helped too.
Boyd suggested that now, with all my clean-ups, I actually CAN get that extra knot
or two added to my top airspeed if I now dial in an additional degree to my
prop pitch. At the same power settings as before, I should now see a bit more
airspeed. Didn't think of that - I might try it.
Dennis Kirby
Tackling the drag on my Kolb, one molecule at a time
do not archive
Message 2
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| Subject: | Re: Drag reduction |
maybe a quarter to half degree.... a full degree may be a bit much....
boyd
>>>>>>>>>>>>>>>>>>>>>>>>>>
Boyd suggested that now, with all my clean-ups, I actually CAN get that
extra knot or two added to my top airspeed if I now dial in an additional
degree to my prop pitch. At the same power settings as before, I should now
see a bit more airspeed. Didn't think of that - I might try it.
Dennis Kirby
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Message 3
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| Subject: | reduced drag and speed. |
kolbers... maybe I should explain my thought process,,, it seems logical
to me... but I am a retired plumber, not aerospace engineer.
I think when Dennis has reduced drag, he said he is at the same speed, ru
nning the same power settings, at the same rpm... ( at least that is what
I comprehended).. but with reduced drag. the same rpm is not the same p
ower setting,,, this is evident by the reduced fuel consumption. when m
aking changes, it is best to change only one thing at a time. thus you can
quantify the changes to the results. now that Dennis has reduced the dra
g, and kept notes on the changes,,, IMHO in my humble opinion,,, in orde
r to quantify the changes, he has to get the power setting back to the orig
inal settings. he could do this in 2 ways,,, first, increase the rpm ti
ll he reaches the same fuel burn, that should show an increase in speed,,,
second, and the purest change here is increase load on the engine equal
to the drag reduction, by increasing pitch, so he gets the same rpm at the
same fuel burn that he had before drag reductions. with the same rpm a
nd fuel burn the net difference in speed would be the benefit of reduction
of drag.
I am sure there are some on the list that could tell me if I have thought t
his through correctly,,, or if I am full of wishful thinking.
boyd young
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Message 4
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| Subject: | reduced drag and speed. |
Hi Boyd Y/Kolbers:
My qualifications to comment on this are few. I am a retired soldier.
Beans and bullets is about all I know.
I buy your theory.
While experimenting, you can use different prop settings to accomplish your
goal.
If it was me, when it comes to prop pitch, I would continue to use the same
practice as I always have:
Just bump the red line, for a 912UL it is 5,500 rpm, at wide open
throttle/straight and level flight. When you get that, you have gotten to
best performance for climb and cruise. The engine is happy. The airplane
is happy. Therefore, the pilot and experimenter is happy, I hope. ;-)
john h
mkIII
Titus, Alabama
: Kolb-List: reduced drag and speed.
kolbers... maybe I should explain my thought process,,, it seems logical
to me... but I am a retired plumber, not aerospace engineer.
I think when Dennis has reduced drag, he said he is at the same speed,
running the same power settings, at the same rpm... ( at least that is
what I comprehended).. but with reduced drag. the same rpm is not the
same power setting,,, this is evident by the reduced fuel consumption.
when making changes, it is best to change only one thing at a time. thus
you can quantify the changes to the results. now that Dennis has reduced
the drag, and kept notes on the changes,,, IMHO in my humble opinion,,,
in order to quantify the changes, he has to get the power setting back to
the original settings. he could do this in 2 ways,,, first, increase the
rpm till he reaches the same fuel burn, that should show an increase in
speed,,, second, and the purest change here is increase load on the
engine equal to the drag reduction, by increasing pitch, so he gets the same
rpm at the same fuel burn that he had before drag reductions. with the
same rpm and fuel burn the net difference in speed would be the benefit of
reduction of drag.
I am sure there are some on the list that could tell me if I have thought
this through correctly,,, or if I am full of wishful thinking.
boyd young
Message 5
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| Subject: | Re: Drag Reduction Paradox |
At 01:32 PM 3/11/2014 -0700, you wrote:
>
>>
>> file:///C:/Users/Charlie/Downloads/Streamline_SAA.pdf
>>
>> Charlie
>
>
>Um - Charlie? I don't think that's a web url -
I think it's a file on your hard drive.
>
>--------
>Richard Pike
>
Could this be what you are looking for?
http://www.jackbhart.com/firefly/pdrag.html
Jack B. Hart FF004
Winchester, IN
Message 6
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| Subject: | Re: Drag Reduction Paradox |
Also waxing your airplane will increase efficiency & speed. On my Rans S-7 after
I put wax on I gained 3 to 5 mph at cruise & top speed.
--------
"Life should be lived as a bold adventure, I refuse to tiptoe through life
just to arrive safely at death"
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=420213#420213
Message 7
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| Subject: | Re: Drag Reduction Paradox |
I haven't noticed any one saying any thing about vortex generators to help
performance. I have a Mark 111 / 912 80hp with the enclosed rear area=2C f
airing on the struts=2C steel landing gear with tundra tires. After instal
ling the vortex generators I noticed a lower stall speed=2C increase in cru
ising speed and climb. There was also a decrease in fuel usage both solo an
d duel. My main reason for installing them was the short field and beach l
anding and take off...less roll out and was surprised by the above added ad
vantages.
> Subject: Kolb-List: Re: Drag Reduction Paradox
> From: heracesthesun@yahoo.com
> Date: Wed=2C 12 Mar 2014 12:03:48 -0700
> To: kolb-list@matronics.com
>
>
>
> Also waxing your airplane will increase efficiency & speed. On my Rans S-
7 after I put wax on I gained 3 to 5 mph at cruise & top speed.
>
> --------
> "=3BLife should be lived as a bold adventure=2C I refuse to tiptoe th
rough life just to arrive safely at death"=3B
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=420213#420213
>
>
>
>
>
>
>
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Message 8
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| Subject: | Re: Drag Reduction Paradox |
smlplanet(at)msn.com wrote:
> I haven't noticed any one saying any thing about vortex generators to help performance.
I have a Mark 111 / 912 80hp with the enclosed rear area, fairing on
the struts, steel landing gear with tundra tires. After installing the vortex
generators I noticed a lower stall speed, increase in cruising speed and climb.
There was also a decrease in fuel usage both solo and duel. 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.
>
Yep. My experience exactly. Isn't it wonderfully simple and straightforward?
Enjoy.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
My soul shall be joyful in the LORD; It shall rejoice in His salvation. Psalm 35:9
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=420251#420251
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