MTT

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Hi, guys I have the following question. I just started building a DFS Reiher III, a german glider from the 30's, from a plan, its 1:5 scale, and will have 3.8 meters wingspan.
The plan has a NACA 6409 airfoil for the wings. I don't know if this airfoil is good or bad, the only thing I don't like about it, is that it has a very pronounced undercamber, so I feel that it will be pretty difficult to cover with iron on fabric like 21st Century or the likes. Thats why am thinking of using another airfoil, maybe the SD 7037. Would that be a good choice ? Any other recommendations ?

Thanks, Michael

CoosBayLumber

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I have a J.A.S.CO. Thermic 72 and it specifies the same airfoil as yours. I think it was popular during the 1930's for gliders. The airfoil ought to work as intended.

I have several other older gliders with undercamber wings. Zero problems with covering them. Remember you have to cover them in three steps. Bottom 2/3rd, then top, then front 1/3. Stick the covering to everything on bottom surfaces.

Take a look at the plan for the Sinbad 62 at Jo Jusko plan site at Fort Worth M.A.Club for example of undercamber wing.


Wm.

Dragon Soaring

IMHO the NACA airfoil will look better on it

The under camber = lots of lift but small speed range
7037 will give better performance

With the 7037 I would add flaps for camber changing

SeeYa

SZD16

Use either the HQ3.5/12 or the S4233 both of which are very good airfoils that can carry a bit of weight.....and they look scale to boot.

Vince

My Feedback: (1)

Try the following link for a vast library of airfoils.

http://amber.aae.uiuc.edu/~m-selig/a..._database.html

Vince