Have specs - Seeking airfoil expertise

[Mike James]

Hi everybody,

I'm building a new pusher-powered sport jet, and have the basic planform set. I would appreciate your opinions on the best airfoil choice for this application.

Overall length 60"
Wing span 42"
Root chord 20"
Tip chord 5.5"
Average chord 12.75"

Sweepback at 25% chord line:
Area (projected through CL) 535.5 sq. in.

Wing loading at 8 pounds 34 oz./sq. ft.

Expected Max speed 125 mph
Reynolds number @ 125 mph 1.25 million
Reynolds number @ 25mph 248,625

Since this is to be used with a pusher prop, there will be no propwash
over the wing. The wing will have plain flaps and LEF, and fuselage LEX, contributing to lift at high AOA. I expect to use a couple of degrees of washout.

Thank you!

[Ollie]

The NACA 63-015 at the root and NACA 63-009 at the wig tip will give a good turn of speed and good inverted performance.

The taper and sweep will give a vicious tip stall at medium to slow speeds without the flaps deployed unless huge (more than about 12 degrees) washout is employed and the wash out will spoil inverted performance. Airfoil selection won't affect this trade off much. You just can't have your cake and eat it too with this kind of a wing.

Flap coupled to elevator will give you the washout you need for medium speed aerobatics without spoiling inverted performance. The mixing ratio will have to be worked out in flight testing for each CG location and pitch trim. The closer the fuel tank is to the CG the better this scheme will work.

"Everything affects everything else."

[Mike James]

Thank you, Ollie.

I'd like to use an airfoil more in the 8% to 10% range, if possible, to look more scale-like, and to blend with the LEX better.

Is there a thinner semi-symmetrical section you can think of that might work? (Bob Violet's planes, as well as many other scale jets, fly with scale airfoils, which is why I think this would work at medium to high speed.)

I understand that this affects inverted performance, but that's not a major issue with me. I'm hoping that flaps and LEF will solve the low speed problems. (Fuel can be carried on the CG.)

Thanks!

[Ollie]

The NACA63-010 will work just as well or better at the wing root. You could even use an NACA63-006 at the tip if you had enough thickness for the LEF mechanism.

[Mike James]

Thank you again, Ollie. I appreciate your advice.

[rcjetpilot]

FYI

ROOT TIP
F-16 Falcon NACA 64A204 SAME
F-18 Hornet NACA 65A005 mod NACA 65A003.5 mod
F-22 Raptor NACA 64A?05.92 NACA 64A?04.29

[Mike James]

Thanks for the scale info.