Hi, just finished my prototype:

Before building the FZ3, i decided to build a prototype first, as there will be a few differences with the FZ2.

The PT is build from 3mm depron, glas covered and painted wih "RC colors", 4w HET motor, 3cell. Sizing of the PT is made as such, so that the cubic wing loading is the same as for the original FZ3. Aileron and flap are resized in order to have a representative flying experience as would be with the FZ3.

I simplyfied the front wheel, it's more like a skid, not streerable, just to find out if it is possile to take off with this odd setup (cg in the center of the 3 "feet" and the winglets-feet being far behind the cg).

I made some attempts to make the skid a retract with a servo, but the forces are huge during takeoff, the frontskid itself and also the servo broke on several occasions. Decided to have a front skid without retract. This turned out fine, the wing has to make a nice speed, before it's able to takeoff. This is due to the odd setup, the wing cannot be tilted to catch more air. The skids are designed to have the wing at an angle of attack of 6° during takeoff.

Having 30° of sweep, with winglets upside down, showed me that the wing is stall prone at low speeds, especially during landing: the ailerons lack authority at low speed. In order to keep the design clean, I decided not to add top winglets, but installed fences instead. These should be a able to limit the spanwise crossflow, which induces the stall behavior. Yet to see if this change turns out as expected.

http://www.rcgroups.com/forums/member.php?u=271334

Vincent, that looks so COOL! Even without the LG the lines are great. I like that underslung fuse and the dropped winglets. Actually, it would look as good inverted. DO you have any pics that show the fences?

... Oops, just saw your blog with the views I requested, so as Emily Litella would say, "Never mind." The video there indicates a beautiful build, too. This plane gets more and more interesting.

Hey, thanks Potshot, nice to hear you like the design.

For now, the front skid is left as such, the retract function was great, at least it worked nice on the workbench. But during takeoff, it cracked.

I leave the premiere to the FZ3, which will get a proper retract will steerable wheel. I know it will never look as cool as with he skid....hmm perhaps i should rethink the skid.

The skid of the PT can be removed for landing in high grass, while being handtrowed.

So were the fences as effective as you anticipated?

don't know yet, waiting for better weather conditions

Originally Posted by vincent123

don't know yet, waiting for better weather conditions

I know the feeling. Long time until Spring.

Tested the wing fences today, it feels a bit more solid, more authority during landing. Nevertheless, ailerons seem a bit too small for a swept wing, no prop at high speed, but while landing i need more throw.

Some footage of a takeoff:

Flying Wing With Landing Gear (1 min 48 sec)

Very cool, Vincent. BTW, what are these?

Just two pins to fix the front landing skid

Ah. Thanks!

Proceeding to the FZ3 build, based on the Prototype

Still using a skid?

Nope, plan is to use a full option spring loaded retract, steerable, and hidden behind a kind of "door" (or how do you call that?).

Still having the trailing skids, which are actually the up-side down winglets.

1 face sheeted, 3 to go!