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Old Yesterday, 11:08 AM
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Wing sections, Goldberg Eagle 63 and Berkeley Ryan Navion

Hello my friends, Two issues:

Goldberg Eagle 63: A friend of mine, is surprised by the fact that Carl used a funny airfoil section in the Eagle 63 instead of the one used in several other trainers such as the Kadet. Any experts out there know what advantages he found using this airfoil instead of the Clark Y of the Kadet?

Berkeley Ryan Navion Super 260: I'm planning to build this model. The excellent plan restored by Planeman only shows the wing section of the left wing more or less in the middle of the panel. On one advertisement (attached) when the original kit was launched (1955) Berkeley states that Henry Struck, the model's designer, used an airfoil at the root changing to the tip to other. The original plan only includes the airfoil shown on the attached image. What happens if I develop all the ribs from this section? Will the model behave differently or become unstable? Why did Struck used this changing airfoil? Opinions welcomed and thanks to all my friends.

EDUARDO
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Old Yesterday, 02:19 PM
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Eduardo-

I heard a rumor (probably read it on the Internet, so it must be true) that Goldberg developed his airfoils by tracing the outline of his right shoe. Maybe that's how the Eagle 63 was done.

There's some discussion here about airfoils for Berkeley's Navion. I'd probably use the scale airfoils (NACA 4415 & 6409) 'cause I'd fly as a scale plane. I used the scale NACA 2416 & 4409 on my 72" Chuck Hollinger Fairchild PT-19 and really like the way it handles (though those have flatter mean line (better inverted) than the Navion's 4415 & 6409). Use Profili or similar to interpolate from root to rib.

If you're more after some aerobatics, I might go with something semi-symmetrical like on Musciano's plan, or just go with an old standby like NACA 2414. If you do this, or otherwise use the same section root-to-tip, be sure to include washout.

BTW, in NACA 4-digit airfoils, the first digit is the max y value (camber) of the mean line (midway between upper & lower surfaces), in percent of chord. The 2nd digit is distance of of this max from L.E. in tenths of chord. the last 2 digits are thickness in percent of chord. This from "Theory of Wing Sections" by Abbott & Doenhoff, which includes formulae.

I like Berkeley's Navion, too. Be sure and keep us informed....

-Dave Plumpe
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Old Yesterday, 02:31 PM
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Quote:
Originally Posted by DPlumpe View Post
Eduardo-

I heard a rumor (probably read it on the Internet, so it must be true) that Goldberg developed his airfoils by tracing the outline of his right shoe. Maybe that's how the Eagle 63 was done.

There's some discussion here about airfoils for Berkeley's Navion. I'd probably use the scale airfoils (NACA 4415 & 6409) 'cause I'd fly as a scale plane. I used the scale NACA 2416 & 4409 on my 72" Chuck Hollinger Fairchild PT-19 and really like the way it handles (though those have flatter mean line (better inverted) than the Navion's 4415 & 6409). Use Profili or similar to interpolate from root to rib.

If you're more after some aerobatics, I might go with something semi-symmetrical like on Musciano's plan, or just go with an old standby like NACA 2414. If you do this, or otherwise use the same section root-to-tip, be sure to include washout.

BTW, in NACA 4-digit airfoils, the first digit is the max y value (camber) of the mean line (midway between upper & lower surfaces), in percent of chord. The 2nd digit is distance of of this max from L.E. in tenths of chord. the last 2 digits are thickness in percent of chord. This from "Theory of Wing Sections" by Abbott & Doenhoff, which includes formulae.

I like Berkeley's Navion, too. Be sure and keep us informed....

-Dave Plumpe
Hu Dave. I'm recovering from laughing for the last 30 minutes after your comment on Goldberg's sections.

As for the Navion, I like the section shown on the plan because it is easier to build and also looks more scale. Musciano's section looks a little odd for this model. My intention is to fly the Navion and watch this most beautiful design boring holes in my Colombian beautiful sky, so I think the plan's section would be good enough. You mention 2416-4409 from Hollinger's PT-19. Which one would you prefer for the Navion? And finally, you mention Profili for ribs interpolation. I have no idea on this, can you give me more information? I am bad on using CAD but I can use CorelDraw if possible or any similar software to get each rib. As for the full-size Navion's airfoils I have seen that the tip section is undercambered!!!!!! Naturally I'll inform my friends here on my Navion's progress.
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Old Yesterday, 04:31 PM
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Eduardo-

I think the rib shown on the plan would do fine for hole-boring. It's about a 14% section. You'd get slightly better aerobatic/inverted performance with a semi-symmetrical section like a NACA 2414, but the plan's flat-bottom section might look more scale. Include washout if you go with constant section root-to-tip.

Profili is a computer program for plotting wing ribs. You can pick a standard rib section from its built-in library or design your own, then specify chord and planking thickness and print it out. You can also specify different root and tip sections, chords and number of ribs for a tapered wing. I used Profili 1.2. I see they're up to version 2 now. You can download it from here. Looks like you can download a crippled version for free, but for the basic version for modelers they want 15 euros. I'm sure there are other airfoil-plotting programs out there, probably some are free.

I've attached the 12 ribs for the Berkeley Navion, assuming the center 5 ribs are identical. Note how the section varies smoothly from root to tip. There's some bumps around the nose of the 4415 you'll have to smooth out. The plots show 1.5mm planking (I assume your balsa is metric). If you want to print the pages, print them at full size (not scaled to fit). The 3 pages are on US Legal size paper (8.5x14 inches), but I'd think would print out OK on metric paper - if not, holler and tell me what size paper.

-Dave
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Old Yesterday, 04:53 PM
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Dave:
Thank you very, very much for the ribs which came as a wonderful surprise. Thanks again!!! By the way. I'll install spars etc. as per plan. I'll cut ailerons and flaps after assembling. My favourite way. Very interesting the rib software. I'll get one and give it a try.

Yes, we are metric so we get 1.5 balsa here. No problem with the "nose" on the ribs. I won't print them, I'll vectorize them with CorelDraw for my laser cutting machine.
In the mean time, I am just starting the fuselage. All formers are on the plan except some cabin ones but I have already worked them out with Corel. Not an easy model but quite challenging.

As for Goldberg Eagle 63 section, Your opinion; Do you think there would be any improvement or non improvement if I change to Clark Y? This is for a short kit I'm cutting for a friend of mine.

Thanks again

EDUARDO
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Old Yesterday, 06:19 PM
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Eduardo-

I'm certainly no airfoil authority, but the Eagle 63 rib does look strange to me. The relatively sharp nose I'd think would make it stall earlier and the flat rear end wouldn't seem to provide any lift - it's the curved airflow that lifts. Unless someone claims it has special qualities that are great for trainers, I'd go with the tried 'n true Clark Y.

I'm not familiar with CorelDraw. If it could input .dxf or .dwg files, I could've provided the info easier. I brought up the plots in Profili, exported the individual ribs as .dxf files, imported them into Autocad, labeled and arranged them, and "printed" to pdfFactory to make the .pdf file. I still have the Autocad .dwg file, if that will make your task easier.

-Dave
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Old Yesterday, 07:22 PM
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Quote:
Originally Posted by DPlumpe View Post
Eduardo-

I'm certainly no airfoil authority, but the Eagle 63 rib does look strange to me. The relatively sharp nose I'd think would make it stall earlier and the flat rear end wouldn't seem to provide any lift - it's the curved airflow that lifts. Unless someone claims it has special qualities that are great for trainers, I'd go with the tried 'n true Clark Y.

I'm not familiar with CorelDraw. If it could input .dxf or .dwg files, I could've provided the info easier. I brought up the plots in Profili, exported the individual ribs as .dxf files, imported them into Autocad, labeled and arranged them, and "printed" to pdfFactory to make the .pdf file. I still have the Autocad .dwg file, if that will make your task easier.

-Dave
Definitively Goldberg plotted his airfoils with his fashion right shoe!! I'll tell my rfriend to use the Clark Y!!

The drawings you sent me are fine for vectorizing in PLT for laser cut via CorelDraw. No additional information is required.
Thanks again and best wishes!!

EDUARDO
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Old Today, 08:25 AM
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Goldberg's shoe airfoil: would that be a Florsheim?

Jim R.
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Old Today, 08:39 AM
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What's Florsheim?
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Old Today, 12:19 PM
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Quote:
Originally Posted by JRuggiero View Post
Goldberg's shoe airfoil: would that be a Florsheim?

Jim R.
I'd think Keds, most likely. S'pose there's much difference at our low Reynolds numbers?

Eduardo: Florsheim & Keds are/were shoe brands. Florsheim relatively upscale, Keds bottom scale tennis-type shoes. At least back in my day.

-Dave P.
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Old Today, 07:03 PM
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Not available here. Thanks for clearing the matter
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