Uwe Heuer designed the Marumba 2m to have near-zero lift at zero control deflection. The flaps and elevons work in opposition to produce a "snap-flap" effect. Uwe is an advanced designer and pilot... just look at the videos of his wings in flight.

I suspect that the control surface layout he used must have very little pitch input from the flaps.

Marumba Flugerprobung - incl. Rückenflug (1 min 41 sec)

And this for some slower flight, (about 2 deg down flap and 2 deg up elevon... just a guess)

Hangpfeil Marumba bei 3 Bft (2 min 32 sec)

And this showing its bungee launch ability,

Pfeilnurflügel Marumba, Testflüge an Flitsche (3 min 55 sec)

Beautiful!

There is something about a swept wing with winglets. Exotic, slick and simple.

~Bryan

This is off-topic but I feel it is really important to document my results (good or bad) so everyone can judge for themselves.

Of course, the best way to document and judge a new RC plane design is to show it in flight but I've been having trouble getting the plane centered in my videos. If the plane is flying low or on the ground, it's at the bottom of my video or cut off. If the plane is at the apex of a launch, it's at the very top of my video or cut off. The problem is that the camera is fixed to my head but my eyes are looking up during flying or looking down at landing. It's tricky to track a plane with your whole head.

So.......I've made a high-tech, adjustable tracking device .
Some old RC control linkage parts were used to mount to my cap and a piece of spring steel was bent to just appear in my field of view. I'm not focused on it during flight so it's just a blur but should be visible enough to allow me to use it as a sight to aim the camera at my plane at all times.

I'll try it the next time I fly and see if it really helps or if it's just a distraction .

Your sight (training wheels) will certainly help you to train to simply point your head at the plane. It is not natural to face directly at what you're looking at so it is a learned behavior. Doing so will take a little attention away from flying. For me, facing the plane, it is second nature at this point.

Having an angle adjustment on the camera is also a big plus. GoPro has a excellent adjustable headband not to mention an app that allows you to see the live image on your phone so that you can center the frame before you fly. How dare you not turn to your phone to solve this problem!!! What kind of Millennial are you?

A truly bad solution to this problem is to use a wide angle lens in which the plane will be a tiny dot in the frame.

Remember: If it's not on video, it didn't happen......

Helmet cam is the way to go..............

Check out the smooth pans and perfectly framed shots in this video. I used an action camera for the perfect focus without the need for auto focus, which is always a problem, so it is too much wide angle, but the assumption is that the viewer is smart enough to go full screen on high resolution.

Hyper Hatchet - A few landings (4 min 11 sec)

Millennial? Ha!
I'm a baby boomer . I didn't have a smart phone until I was in my 40's.

Great video. You really have your plane centered but my favorite part is your "touch-and-go" off the sand!

My servos are about 10" outboard from the root so I needed a way to cut a channel for the servo wires. I've done this in previous wings by cutting a "U" channel in the foam core, then capping the opening. I was looking for a simpler way this time so the wings were laminated without any precut channels and I made a simple drilling jig with a 2x4, a couple clamps, my drill and a cheap, 3/16" dia. 12" long drill bit I got from Harbor Freight.

It was a little tricky getting things lined up on X,Y and Z but it worked. I clamped the drill in place and slid the wing (on its saddle) onto the bit.

The elevons were cut out using a razor saw (pic 1). Blue tape is an easy way to indicate where to cut.
Control rod channels were drilled by hand using a homemade bit from a 1/8" dia. brass rod and using more blue tape as a guide.

Here is my design for the fuselage. The two boxes in front are the battery and Rx volumes.
The profile is just the same airfoil scaled large enough to fit the electronics and to extend fore and aft for CG balancing and gripping for launch.

It will be made from balsa sheeting and spread tow carbon similar to the prototype.

It's looking good Bryan! The only videos I ever shot were with a camera screwed to the top of an old hard hat. I took stills and shifted the mount until it was about where I wanted it, the used a red Sharpie pen to mark the frame's center on m y sunglasses. It helped me keep the dots on the plane.

Thanks for the encouragement Ed. My biggest challenge to building is lack of motivation and it has been waning .

The servos and control linkage is finished along with extending the servo wires. I found a neat way to route the control rods and servo wires. I used a length of heat shrink tubing (pic 1). It was stiff enough to slide through my wing channels and I simply placed the control rod or the wires inside the tubing, then pulled it back out.

It's always exciting to see the wings together for the first time. It looks like the wing tip chord is huge compared to the root chord but they are actually the same length .

Finally got into some lift yesterday. The static margin is back to around 10% and I added 10 feet to my launch tubing. My Frsky Rx has an altitude sensor so I should learn how to data log so I can maximize my launches.

My hi-tech, adjustable video centering device was tested and it works but it's almost information overload to worry about centering my head along with flying my plane! It only worked when I was actively thinking about it but maybe this would become second nature with more flight time??

I do like the prismatic tape on the LE. There were a couple times where I got disoriented on the flight orientation. I'll probably move up to 1" wide tape from the 0.75" tape that is currently on the LE.

FW 1 bungee launch 2 (2 min 59 sec)

A thermal flight in the dead of winter in Tennessee!
Imagine that. Pretty satisfying. We still have snow on the ground here in Crossville.
The flash from the LE is quite useful. You are getting flashes from both the top and bottom of the wing.

Anybody else flying gliders down in Chattanooga? Would like to see a competition between your swept wing and a conventional DLG............another video opportunity.

I find that if I point my shoulders (square to the plane) at the plane, the camera will follow nicely.

Also you might experiment with pointing the camera down a bit so that the plane is near the upper frame. This will show the ground/trees which adds useful reference, also true for landings and launches.

I have a competition grade DLG (Snipe) and I'll tell you right now, there would be no competition!
The Snipe will easily out-thermal this flying wing.
But that's OK with me. I understood this at the outset of this project. The lure of the wing offsets its lack of performance