Taylorcraft wing airfoil

[PA1195]

Hey Dr. Tim try to get the dimension from the Tern. It's local and I know the pilot Gordon Clark wouldn't mind. I have more pics of the setup but lost your e-mail. Personal it to me and I'll send them.

I also wonder if the current TCDS holder of the Tern has prints? http://www.interstateaircraft.com/Contact.html

I assume the upper rear jury strut bracket shown in #10 fastens to the back of the rear spar. From that I can measure the wing hinge back and down distance minus assumed rib depth. On the flap then chord, thickness, hinge location from the LE/TE and distance below.

Alternatively the pics of the Taylorcraft hinges in #10 show that mod to the aileron hinges. If we assume they took an aileron hinge - mod it - then did the same to an aileron to match the dropped hinge point you'd have most of what needed to CAD the relative positions. Build the brackets and cove area with a built-in upper lip plus any torque transfer compression tubes between the spars like Piper.

As far as aileron cove design the Cubs (J-3>PA-18) use a similar design to the Taylorcraft. However the Cruisers PA-12>14 uses a sloped up cove like the Tern with a changed Frieze aileron with sharp LE that drops below the wing I guess to tame adverse yaw. When flaps were installed on the PA-18 the sloped cove was used in front of the flaps.

Gary

[PA1195]

Here's some 23012 flap designs: https://ntrs.nasa.gov/archive/nasa/c...9930091739.pdf

Gary

[otrcman]

Gary,

Looking at TR-664, it appears that the drag increase at low angles of attack and flaps zero sort of offsets any gain on the low speed end with flap deflected. That, in conjunction with the rather abrupt stall makes the 23012 appear to be a dead end street to me. Perhaps using spoilers to put more weight on wheels so braking effectiveness is improved during landing roll would shorten landing distance just as well as reduced touchdown speed with flaps.

Dick

[astjp2]

Gary,

Looking at TR-664, it appears that the drag increase at low angles of attack and flaps zero sort of offsets any gain on the low speed end with flap deflected. That, in conjunction with the rather abrupt stall makes the 23012 appear to be a dead end street to me. Perhaps using spoilers to put more weight on wheels so braking effectiveness is improved during landing roll would shorten landing distance just as well as reduced touchdown speed with flaps.

Dick

Washout reduces the abrupt stall to a nice flutter

[PA1195]

Hi Dick. I read this first in 1975 and maybe once since so did reread thanks to your thoughtful comments. I'm not an engineer and my landing goal would be to land as slowly and short as possible with a low AOA for best forward visibility. My takeoff goal would be to minimize the takeoff distance. Obstacle clearance requires balancing lift vs drag at a given thrust over a critical distance. Therefore that Vx might require a longer takeoff to achieve the ROC required to top the tree. For Vy retract flaps to minimize drag.

I've never flow a flapped 23012 plane but have flown others (Beaver, various Cubs, Citabrias, and Cessnas - mainly C-185). Flaps are a tool to use when needed and I've yet to wish I hadn't deployed them. But yes for speed vs power the plain Taylorcraft wing is probably best providing the landing gear isn't the limiting drag - like floats or large 31" Tundra tires for example.

The stall can be tamed with VG's in my experience to the point of flying nose high with nothing but clouds for view. Washout softens the stall but at some expense of overall lift. That's a personal choice.

My dislike of the airfoil is that it takes more AOA to create lift over even the common Cessna 2412 (and especially with Sportsman Cuff,) Bellanca's 4412, and Cub's USA-35B mod. Run a C/L plot of 23012 vs the others and compare. It's sometimes a minimal difference but present. Taylorcraft set the wing incidence at 3.8* to minimize L/D in cruise and add lift. Others are set at about half that value (+-2*). They made the wing area large to reduce the loading per unit.

As weight increases over the original designs 1100-1200# more lift is needed to achieve the same T/O and landing performance (opinion). Yes more power and better prop helps acceleration and climb but comes at a price in balancing CG and increased fuel capacity needed to feed a mission profile. Flaps and L/E devices can be a useful tool in that situation and that's what happened when other manufacturers adopted the airfoil. They wanted both speed and lift and flaps helped them achieve that goal I believe.

Gary