Airfoil series MID-36,-37,-38,-39 for F5Js
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by Slobodan Midic (c)
Airfoils Mid-36 up to Mid-39 are thin with small cambers so they are
suitable for RC flying models class F5Js. Models equipped with these
airfoils have good penetration to the wind and because of very small
drag sinking speed is small. Series have added designation "s" behind
F5J, what means "speed" to the difference of "normal" series Mid-31
up to Mid-35, for quiet weather, when the power factor is of the first interest.
When I designed these airfoils have in the mind F5J, but smaller and
lighter models of 2.5m span, where wing are not very loaded by
bending forces. Normally who will use this series for regular F5J to FAI
rules, span 4m, must take into account enough strong spars for these
thin airfoils.
Geometric Characteristics
Foil.....th[%c]..cb[%c]..r[%c]
--------------------------------
Mid-36...7.50....2.35....0.51
Mid-37...6.95....2.35....0.43
Mid-38...6.47....2.12....0.39
Mid-39...6.00....1.90....0.38
Note: th=thickness, cb=camber, r=radius of leading edge, c=cord
Most interesting disposition of airfoils from root to the tip is:
Mid (36-37-38-39). Of course different combinations are possible but
disposition like (37-37-38-39) is of minor importance for the better
speed, or better power factor.
Novi Sad, 10.Oct.2017
Slobodan Midic