Long EZ Wing and Strake Modification

[hdmx]

Performance aspects aside, many modifications are done because of personal preferences regarding aesthetics. For my "Long EZ" build I have invested lots of time in planning and re-designing to make an aircraft that does not only perform well but also looks great for me. The original Long EZ plans were designed also for an easy homebuilt construction which does not require a lot of tools or machines. With technological advancements, we homebuilders are able to construct more complex geometry with little effort.

I wanted to have an aircraft geometry that transitions smoothly. In this thread I want to focus on the kinks in the strakes as well as the wing and how the winglet is attached. Per original plans the strakes/wings have three large kinks at BL23 and BL55.5 which disrupts lines.

Image 1: Original Long EZ wing and strake

I don't know why exactly there is a kink in the trailing edge at BL55.5 but it was easy to eliminate this by adjusting the templates slightly. I also wanted to iron out the kinks in the leading edge of the strakes. This will be achieved with a new construction method. Instead of using the typical moldless construction, I opted to invest some time and money to make a negative mold using additive manufacturing which has become very cheap even for homebuilders. This is currently work in progress so pictures will be updated next year.

Image 2: Modified wing and strake

The other point to smooth out is the winglet. I went for a blended winglet with a smooth transition - leading edge of the main wing and winglet are in a plane. Airfoil is untouched. This leads to a somewhat odd looking trailing edge (in the area of the blend) but I'm okay with that. The winglet will not be added later on but is attached while constructing the foam cores, making the construction a little more complicated - but it also means that the wing spar can reach into the winglet. The blended part makes actuation a little more complicated as the original design can not be used. This is not final but I will use a bowden cable with a single bend to reach up into the winglet and then a mechanical lever system which will actuate the rudder.

Image 3: Modified wing with blended winglet

Some 3D printed tools and a homebuilt 3 axis CNC machine was used to mill out the blended part, which is also XPS. There's free software like Fusion 360 for CAM - works great. Due to height constraints (my machine can only mill parts up to 150mm in z-direction), I had to split the 90° blend into two 45° blend foam pieces.

Image 4: CAM - planning the CNC milling with a jigs, piece is milled from two sides

Image 5: Milling out a 45° blend foam core

Of course jigging foam cores is much more difficult with this design. I CNC milled some jigs and had to construct not one but two tables with jigs at different heights that were also perpendicular to each other

Image 6: Planning of the tables and jigs in CAD

Image 7: Shear web reaches up into the winglet

Image 8: Foam cores set up including the blended winglet

 

Just wanted to give you guys a small preview of my plans and what I have done so far. I don't know if this is helpful/interesting so please let me know if you are interested in more updates or not

 

Best regards,

Rene

[jridge]

Wow.  That's impressive.  You've put in quite a bit of work here.

I can't wait to see what other mods/changes you're incorporating.

Keep posting here.

Jeff