Here's my 48in KFm 2 Blended Wing, Double tapered flying wing with  some interesting learnings.

 Some specs:

 Span: 48in
 AR: 6, average chord : 8in
 Ele: 2226 1800kv motor, 10 A, 6x4 and 5x5, 3S 610-850 mAh
 AUW: 410-425g depending on batt.
 WL : About 5.6 oz/sft.

 

....the journey from the maiden to how it flies now has been quite interesting.....here's the story in brief.

As is natural with such wings, I expected it to be pitch sensitive....however on launch at 0.25 throttle, she took to air effortlessly. On trying to turn, it banked sharp left, spiralled and dived down. With some throw adjustments, she was only a shade better in the subsequent flights - twitchy, unpredictible and a pain to fly 

...I just experienced a very classic behavior - the dreaded tip stall.

Stage 1 mods: Increased the width of the aileron by 0.75 in and added Vortex generators/stall fences on either side.

- noticeable change in performance.

Stage 2 mods: Increased the chord of the fins so as to be in line with the TE of aileron.

- again, noticeable improvement in flight as this increased both yaw and roll stability.

 Stage 3 mods: glued/taped a 8" drinking straw to either wing tips at the leading edge - these are called wing cuffs/dog tooth.

+ added a wooded spar at the KF step to reduce the wing flex along the aileron (it already has CF tubes in the coro flutes, but not sufficient as it needed more 'section'. this spar changed the CG and had to add about 20g on nose weight.

 The WL to start with was about 5.13 oz/sft....all the mods resulted in a WL of 5.6 oz/sft.

 She now flies beautifully and have been able to get about 20+ min flights with power + gliding and some juice left in the battery.

 Overall, very satisfied with a slightly unconventional low WL, double tapered, flying wing.

 

....in pic 1, you would see a small white dot on the leading edge of the wing (away from you)....thats the straw glued/tapered as a wing cuff.

 

@bmblb,
Good to see some original experimentation.
Pl post more pics of dog tooth, and describe effect on performance.
Regards.

Thank you, Iyer Sir. Here's a pdf http://phil.zatetic.com/school/AAE_415_Presentation.pdf you'll find interesting....a co-enthusiast shared with me. Actually,this is my second blended wing....the first one was a 1m span, kfm4 airfoil with a WL closer to 6 oz/sft.................she flew great from the maiden on.

a closer look at the dog tooth

This picture makes it clear!
Using a straw is a great desi jugaad 

Great project. Shade early.could have been part of sweepstakes

Nice build

Nice build.

Thank you All for your interest and pardon me for not acknowledging earlier. I wanted my 100th post to be the Sweepstake entry.....here it is....a gull wing flying wing http://www.rcindia.org/electric-planes/2015-sweepstakes-entrant-42'-gull-wing-fling-wing/msg229212/#new

Iyer Sir....the straw is not my idea....as I had mentioned earlier, a co-enthusiast had already tested it and recommended it.

Nevertheless, designing this plane and introducing the changes discovered along the way and seeing the turn around in its performance have all been a huge high.

makes me feel real hardcore 

just kidding 

.....only surviving video of this beautiful flier......need to edit it.

......version 3: pics and video