ACHIEVING THE BEST REFLEXED AIRFOILS FOR FLYING WING USE IN THE SMALL PLANE CATEGORIES

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Norman

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Link doesn't work for me.
The link works for me... well the parts that my browser security add-on doesn't block by default. It appears to be a South American download page for GENERAL AVIATION AIRCRAFT DESIGN: APPLIED METHODS AND PROCEDURES by SNORRI GUDMUNDSSON which is only 8 years old and still being sold by retailers for between $95 and $600. Here's a Google books link to it
 
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WINGITIS

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Voidhawk, I am on a VPN with NZ selected.

You click the BLUE bar(ARCHIVA)...then top left cross icon flashes for a few seconds...

Then there is a Robot CapTHING, that you click, but nothing comes up

Then you click the BLUE bar again and it starts downloading.

K
 

WINGITIS

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I Just tried it with and without a VPN and you just sometimes have to press the ARCHIVO blue line a few times with a few seconds in between to get it to work...

That is with FIREFOX.
 

Dana

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WHAT IS THE HBA POLICY ON SUCH LINKS THEN?
(I HAVE ASKED FOR MODERATION BY REPORTING THIS MESSAGE)

Posting links to copyrighted material, if not the copyright owner's website, is not allowed. Besides depriving the rightful author of income, it exposes us to legal issues.
 

WINGITIS

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Another small change to the RN Spreadsheet, V2.2, Cosmetic.

No more for now...
 

Attachments

  • MICROLIGHT REYNOLDS NUMBER CALCULATOR V2.2 AUGUST 2022.xlsx
    12.3 KB · Views: 2

WINGITIS

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Just to keep everyone's interest up, here is a recently discovered, RATHER OBSCURE British reflexed airfoil from the early 1920's.

Enjoy..
 

Attachments

  • BRITISH 1920S REFLEX 299 0.2TE.txt
    7.6 KB · Views: 0
  • BRITISH 1920S REFLEX ORIGINAL.txt
    518 bytes · Views: 0
  • BRITISH 1920S REFLEX POLARS.png
    BRITISH 1920S REFLEX POLARS.png
    75.4 KB · Views: 1
  • EARLY 1920S OBSCURE BRITISH REFLEX AIRFOIL WITH ORIGINAL CO-ORDINATES-IMAGE.png
    EARLY 1920S OBSCURE BRITISH REFLEX AIRFOIL WITH ORIGINAL CO-ORDINATES-IMAGE.png
    77.5 KB · Views: 1

Norman

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Just to keep everyone's interest up, here is a recently discovered, RATHER OBSCURE British reflexed airfoil from the early 1920's.

Enjoy..
Now that's an oddball. Do you have any information about its origin? If not the airfoil name maybe what plane it was used on. The pressure coefficient (CP plot) is all lumpy and any attempt to smooth the top just degrades it. After several tries at smoothing the whole shape I looked at small local changes with the mixed inverse method. There's a bad spot on the front lower surface that's causing a huge separation bubble at low AoA (<4°). Smoothing that spot can't get rid of the bubble completely (because that's just the nature of a concave lower surface) but it does reduce the size of the disturbance. Attached is my best out of 8 and the L/D plot at Re=1,000,000:
 

Attachments

  • British 1920s reflexed LD.png
    British 1920s reflexed LD.png
    20.3 KB · Views: 0
  • BRITISH 1920S REFLEX bottom modified.TXT
    5.6 KB · Views: 0
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WINGITIS

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Now that's an oddball. Do you have any information about its origin? If not the airfoil name maybe what plane it was used on. The pressure coefficient (CP plot) is all lumpy and any attempt to smooth the top just degrades it. After several tries at smoothing the whole shape I looked at small local changes with the mixed inverse method. There's a bad spot on the front lower surface that's causing a huge separation bubble at low AoA (<4°). Smoothing that spot can't get rid of the bubble completely (because that's just the nature of a concave lower surface) but it does reduce the size of the disturbance. Attached is my best out of 8 and the L/D plot at Re=1,000,000:
To my knowledge it has never been used on a plane.

I found it in some documentation that is very obscure!

The airfoil is just named "AEROFOIL (D)"

I know how it was created and the method is not the greatest, because I have tested it somewhat, but I guess that was the best they could do at that time....

I put it up for reference.

Yesterday I also found, with a little help from my AI engine a small error in the NACA 2R112 airfoil on the Bigfoil site.

Their NACA 2R212, which is the reflexed one is correct.

I contacted Mike at BIGFOIL and he is happily correcting the 2R112 foil at present, just in case anyone was looking at that one, its the BF-109 one.
 

WINGITIS

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Here is a paper with some CFD analysis versus XFOIL results for some common example airfoils.

It allows people to compare and get the feel for how the point of stall Polar's can vary from what XFLR5 shows and by what factor they may vary.

It is only one paper and there are many others but it covers many of the questions that have been discussed on such matters and has, in some part, a bearing on all the polars shown in this thread..
 

Attachments

  • A_CFD_Database_for_Airfoils_and_Wings_at Post-Stall angles of Attack 2013.pdf
    6 MB · Views: 5

Sraight'nlevel

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Reynolds number is real ...what I have experienced so far...the bigger the better....when creating lift.
 

WINGITIS

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Reynolds number is real ...what I have experienced so far...the bigger the better....when creating lift.
Yes that is the trend, if you raise the RN on any test/analysis tool the value of lift will go up in most cases.

But the key is to match the RN you test at to the actual operating requirements you are optimizing for in terms of Chord and Speed of your aircraft.

The RN at stall is less than VNE.
 

WINGITIS

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At the paragliding and hang-gliding sites?
Thank you, but those would be NON-RIGID wings, which are excluded from this thread in the introduction.

But if there are perhaps some SEMI-RIGID ones of thickness that we do not know about that can be analyzed using airfoil analysis tools such as XFLR5 for their reflex properties, well we would definitely like to see them.

Post up images and perhaps the DAT files(as TXT) of their profiles so we can take a look.

In thinking about it someone out there could have conceived a semi rigid fabric covered airfoil that changes its shape with load from one design to another with varying reflex, something to think about for us all.
 
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