Wag aero sportsman 2+2 help! Help! Help!

Hey y'all and thanks for the membership and any help I can get from this forum.

I have decided I'd like to build a PA 14 style a/c. Wag Aero came to mind and I bought a set of plans for the Sportsman 2+2.

Got to the point of getting the wing section copied and stuck together and have hit a snag right away:evil:

If I set my leading and trailing spar centers as they say (at 31"), the chord is an inch short AND the top capstrip doesn't line up on the plans.:roll:

Wag Aero have been zero help at this point and (under the direction of an Aeronautical Engineer) have searched for the type of wing section and a table of X-Y coordinates to check the wing drawings. Like rocking horse poop, I've had no luck, or maybe I'm just not asking the right question.

Can anyone help...TIA.

R

richardscreen said:

Got to the point of getting the wing section copied and stuck together and have hit a snag right away:evil:

If I set my leading and trailing spar centers as they say (at 31"), the chord is an inch short AND the top capstrip doesn't line up on the plans.:roll:

Click to expand...

I'm not really following. You copied the wing profile plans, then lined up the reference lines?

Copying might have changed dimensions. In any event, paper plans can expand or contract with humidity.

I'm building wood wings from the same plans. The wing profile is essentially the same as a super cub's. Christian Sturm's website has drawings. Here is a link to the wing profile:

http://www.supercubproject.com/drawings/pdfs/A3310184.pdf

One caution, though: the Wag nose has a larger radius than what's shown in the drawings. I've decided to stick with the larger radius after talking to various Wag builders.

In any event, I lofted the wing profile using the drawing linked above as a starting point. I then cut up the actual drawing, not a copy, and laid it over the lofted profile. I noted subtle differences, faired lines, and built a jig to that. Chord is right on and centers are at 31".

Look here. http://www.supercubproject.com/drawings/

Oops, Vic beat me to it.

BTW, I'd recommend getting the Northland flashdrive: https://store.straight-level.com/north-land-pa-18-super-cub-drawings/


And order relevant drawings for the PA14 and PA12 from Cub Club.

https://www.cubclub.org/technical-information/blueprints

More plans=more to study=better understanding of the big picture.

One more by the way--

From the drawing linked above, I converted the decimal inch units to millimeters, simply because I didn't have a decimal rule handy but I had a metric one.

I was surprised that the x axis stations were very close to round number metric units. I'm sure the original profile was drafted in centimeters.

FWIW, I generated a table in Excel for the dimensions:

31" is correct... same as -18 etc.... (I just measured one sitting here)

R,
I'm building a 2+2; don't copy the plan for the ribs, cut out the pattern and make your rib jig from that (wood wing, correct?) I've documented everything on my very long build; it's all here on my website marty2plus2.com

Marty

I just got home from work and about to go to bed, but I had to take a quick look here.

Thank you all so much for your input. In just a couple of hours I got all the information I needed to proceed.

Again thank you all, my new friends RVBottomly, Marty57, Skywagon8A and Mike mcs repair.

Question Marty

Marty57 said:

R,
I'm building a 2+2; don't copy the plan for the ribs, cut out the pattern and make your rib jig from that (wood wing, correct?) I've documented everything on my very long build; it's all here on my website marty2plus2.com

Marty

Click to expand...

Do you have a picture of your plan all matched up prior to building your jig?

richardscreen said:

Do you have a picture of your plan all matched up prior to building your jig?

Click to expand...

Marty might have something better, but I dug out the drawing I used last summer and one of my original plywood layouts. The drawing was cut up and taped on the reference lines:



Here is a photo from early on where I drove brads directly through the drawing, removed the drawing, and then faired lines with a batten.



Later, I decided to use the Piper dimensions set out above in post#5. No picture, but use a straight piece of sturdy and smooth plywood, lower edge being the base line, and measure out x points (stations) and then mark the two y points for each station. Drive in brads or finish nails and fair with a batten.

When I laid the drawing over the faired lines last summer, the lines were very close to the laid-out measured lines. This evening I tried it again with the jig I used, and centers are 1/16 short:



Even more bizarre, the nose was almost 9/16 short:



Paper shrinks and expands. In this case, sitting in a heated shop for 6 months led to longitudinal shrinking. That's why it's best to compare to the numbers from the Piper specs referenced in post #2.

Hope that helps.
Vic