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Knoll53's blog
Posted by Knoll53 | Sep 13, 2014 @ 07:22 PM | 1,202 Views
Final round of flap testing after they were lengthen towards the root by over and inch. Pitch response is a problem with flaps. Even modest nose up input causes a stall. If flies OK without flaps.

Razor's Edge - Flap test after body work (3 min 57 sec)

Posted by Knoll53 | Sep 07, 2014 @ 07:03 PM | 1,433 Views
3rd sighting in 6 weeks of a pack of 3 California Condors. Most video lost to auto focus. One of them dropped out and landed while the other 2 disappeared into the distance for 20 minutes, then they returned and soared around the perched one. I left after 1/2 hour and the perched one was hanging tough.

California Condors at Garrapata State Park (2 min 30 sec)

Posted by Knoll53 | Sep 01, 2014 @ 07:22 PM | 1,032 Views
Flying in calm conditions finally settled on 5% static margin for the most aft safe CG. At nearly 12 oz/s.f. and a 4" airfoil, that's about as daring as I get. The flaps proved to induce a little nose down in the calm conditions, which made it difficult to fly with a high AoA for final flare. This plane needs to move even with flaps. I'll add an inch to the flaps before final finishing. Nickels formula was not that far off.

Soberanes, no wind. no thermal, so lots of testing (6 min 13 sec)

Posted by Knoll53 | Aug 31, 2014 @ 09:44 AM | 1,196 Views
Final layout with field tested "nearly" pitch neutral flaps.
Posted by Knoll53 | Aug 30, 2014 @ 11:03 PM | 1,365 Views
Today found a little choppy lift and just put the nose down a bit and let it cruise............this plane is much happier when it's moving. The flaps are 2" shorter now and happily are pitch neutral. They are an absolute requirement for a wing this skinny. There is a learning curve for the tiny flight envelope, but I'm beginning to get it.

Razor's Edge in choppy lift (2 min 1 sec)

Posted by Knoll53 | Aug 24, 2014 @ 07:33 PM | 1,727 Views
Down right windy today which apparently make the local wildlife frisky.
Air Plank and the hawk (2 min 14 sec)

Posted by Knoll53 | Aug 24, 2014 @ 07:04 PM | 1,633 Views
Again some condors flew through in mid afternoon. Only got a few glimpses with the new camera.
California Condor & Air Plank (1 min 21 sec)

Posted by Knoll53 | Aug 23, 2014 @ 11:28 PM | 1,394 Views
Posted by Knoll53 | Aug 17, 2014 @ 08:11 PM | 1,561 Views
Posted by Knoll53 | Aug 17, 2014 @ 07:40 PM | 1,523 Views
Toyed around with a variety of CGs and elevator throws today in the calm hot air of Soberanes Point. The best performance and elevator response is with a very aft CG which brings less than stable handling, but so far, that is my comfort zone with this plane. This flight has the aft CG and you see that it is not exactly on rails. Video cut short due to autofocus problems. Going all manual focus next time.

Razors Edge at Soberanes (0 min 33 sec)


Next up to completely glass the wing in order to combat flutter.
Posted by Knoll53 | Aug 16, 2014 @ 11:44 PM | 1,646 Views
Found an hour today before work and got some testing in after the flap and pod rekit. Nice calm conditions at 9am. Had to rework the CG because the reference mark was lost. Trying different CGs today shows that this plane really performs better with an aft CG. Also, the tip stall is not a problem with a forward CG and IS a problem with the high performance aft CG.
First Bungee (4 min 57 sec)



Short story is that the flaps are pitch positive, as in a lot of nose up. After a few flights, settled on 15% down elevator mixed into flaps to tame things down but am surprised the Nickels formula is so far off. Checking my work now.
...Continue Reading
Posted by Knoll53 | Aug 12, 2014 @ 08:23 PM | 1,551 Views
After a few flights, it's clear that if any wing could benefit from flaps to slow the action down, it is this one. New servos are on their way.....

If it turns out that the flaps mitigate the stall behavior, I'll mix them into the elevator.

Flap sizing based on Nickel's formula.
Posted by Knoll53 | Aug 10, 2014 @ 04:48 PM | 1,576 Views
As expected, this tiny thin wing is not shy about stalling and falling out of the sky. The flight envelope is plenty big, but when it DOES spins you had better be ready. Today proved that it will spin to left every time. Flying with a light touch on the elevator is the solution. The elevator response is very response for a swept wing so I think that the CG is back far enough. For awhile, flew with 2 quarters taped to the nose and performance was noticeably less, i.e. could not soar these light conditions.

Razor's Edge light lift (2 min 27 sec)

Posted by Knoll53 | Aug 10, 2014 @ 10:47 AM | 1,821 Views
Here's a tiny Rhinohide covered flying wing. This one came in at 14.5 oz. AUW or 8.7 oz/s.f., almost a floater but with a 4" chord it moves out nicely. This is the first flight right off of the building board. It has a dramatic spiral dive tip stall that can be "activated" by a variety of moves. Proper CG and limited elevator deflections tame it nicely for slope flying.

Razor's Edge First Flight (0 min 55 sec)

Posted by Knoll53 | Jul 17, 2014 @ 12:49 PM | 2,240 Views
Inspired by a short discussion, here's my approach to a forward swept wing prototype. It features single surface elevator and flaps with a rudder for roll and yaw. Still thinking about how much dihedral to use. Some where in the 3 to 5 degrees range.

What I like about this configuration is that for nose up the elevator/flap deflects down, thus increasing camber and AoA. Good for slow thermal flights and in reverse good for fast slope flying.

Wing skins
PolyC and glass (1 min 16 sec)



Food Wrap at fuse did a nice job of controlling loose glass edges and compressing all. final finish needed minor sanding to remove small ridges.
...Continue Reading
Posted by Knoll53 | Jun 24, 2014 @ 10:56 PM | 3,789 Views
I've been flying a Zagi lately and the only thing it needs is the option of high wing loading.
Posted by Knoll53 | Mar 24, 2014 @ 09:21 AM | 3,401 Views
Looks like I'll get a stab at a rudder enabled, thick plank with dihedral with a rebuild of a Saracen. I'm adding wingtips, a new fuse, tail and elevons. Was surprised to find that the fuse plug became quick stiff after one coat of Poly C. I'll glass right over the plug without tape it first, so the hope is that the Poly C with reduce the amount of epoxy needed.

Saracen redo (0 min 17 sec)

Posted by Knoll53 | Feb 19, 2014 @ 11:47 AM | 3,143 Views
Using the TLAR method for pitch neutral flaps on a curvy, hard to analyze wing.
Posted by Knoll53 | Feb 08, 2014 @ 12:47 PM | 5,656 Views
Inspired by the FootLoose Floater.....it's big brother.

Kent