Does anyone - besides Mr. Millholland - knows what is the wing section used in these designs?
I'm a backyard aerodynamicist and will be building a cabin eagle in the near future (2nd semester 2017). Thus my interest.
Cheers,
Azevedoflyer
Azevedoflyer- As you have seen, from Dan's posting, this has been talked about a few times, and of course it never hurts to be reviewed. During that time, this statement was made-
The consensus at one point according to John Bolding was that the NACA airfoil that is closest is the 4414. However the airfoil has been modified to be a straight line on the bottom.
Also the fact is that the airfoil is a direct duplicate of the Airbike/Minimax airfoil, which is claimed to go by the name of "WP-2" if I am not mistaken. The story goes that Wayne Ison sat down with a #2 wide pencil and drew the airfoil in a stroke of genius...
You may have more results going down the WP2 or mini-max google search rabbit hole trying to run down the actual coordinates...
Edit:
Wayne Ison apparently co-founded Fisher Flying Products, so that may be where the airfoil originally came from...
So the consensus is almost always derived to say-"some of this, some of that
." While that may not answer your question, I will try to shed some light on the whole aspect of "What and why"
1st- building a wing with a flat bottom is far easier, if you build using a flat table for support while working on the top of the wing. If you don't build this way, then perhaps this is not such a big deal. I find that most do, in building the eagle type of wing.
2nd- There are plenty of CAD programs, that will create a perfect spline line based on published X-Y plot points., These of course can then be turned into DXF files for routers or any other CNC based cutting machine. Often creating perfect parts in minutes rather than hours. That is exactly how I created my supplemental plans for the wing. By doing so, I could pre-check and then mate check that each part I drew would fit to the wing build. It would be pretty safe to say, that all mfg. of fair volume aircraft are doing this. i.e., when they make a bell crank, they might make 50, not one at a time, because they know it is going to fit. This is true on nearly every part now. There is absolutely nothing wrong with building each part to fit., as long as you build in the correct order and know that this part goes in the place it was built for.
3rd- There are all kinds of wings for this speed range and thus all kinds of ways to build them. I think it would be safe to say, this is a traditional way, and has worked well for many years. And perhaps nearly the lowest cost way in terms of materials. Would a factory set up to build 50 sets of wings today in this manner? Not likely, but we are not a factory.
4th- The plane, if made to fit all these different wings (and all CG work and calculations) would "probably" fly about the same, because of the speed range. But always note that when one change is made on a aircraft design, it almost always creates 10 more changes... Just the nature of the beast. I will often say and tell. I did not change how the wing was built, or how it attaches to the aircraft, or how the aileron moves, or the shape of nearly all the parts....in other words, I did not do a design change. I simply showed often in 3-D drawings, how the parts should come together. And I also showed many of the parts in full scale, that if built like showed, will fit the other parts of the drawings. Will the wing fly faster, higher, further, better? Not a single one of these points, could be detectable in real life.
5th- and perhaps most important- This is
homebuilt aircraft, 100's of slight deviations happen, even if everyone had the same plans. AS long as structure ways did not get altered, you should be good to go.
Best of success.
