....my gull wing flying wing (http://www.rcindia.org/electric-planes/2015-sweepstakes-entrant-42'-gull-wing-fling-wing/) for 2015 Sweepstakes is almost ready...while 'drawing the lines' I got tempted to make a bird type plane.

....so here are some pics of the progress so far....

......I decided to use bamboo for the spar....here's a perfect piece - (but its also perfect for my crossbow project)....so will have to shave one.

....some more pics.....the spar came out good !

......how time flies ....I realized it was 3am......and stopped after sticking the KFm layers.

....I decided to try a technique I read about for curved wingtips - and it worked beautifully !

Use a heat-gun and bottle for the radius.

Very important :

1.If you decide to use this method, ensure you have a large slab of stone - the ones they use for flooring....or couple(=2 for weight) of regular floor tiles with a clean edge - place this along the whole chord - aligning in a way that there's a clear half inch margin AFTER your aileron.

you can choose bottles of various radii depending on your choice - but ensure it is cylindrical - wine bottles work well.

2. Coro becomes brittle if heated too many times....try to get it right in 1-2 tries. It is necessary to tape it after done to prevent tears.
3. Cut the aileron after moulding the tips.

....the wing tips will continue with the KFm step as normal....another layer of foam comeing there and it will be thinned out to the extreme tips.

Controls:

Stage one: Just elevons should work fine.....depending on how this goes>
Stage two: flaperon+ elevator

Also, there will be no vertical fin specifically......if the curved wing tips are found to be inadequate then I will introduce a fin - using 1.5mm clear acrylic sheet - as soon as I can find it(any leads welcome here)

.....And this would be a prop in slot leaving both nose and tail for all the creativity !

.....the pelican just takes my breath away 

Working with bamboo:

...had the unique opportunity to watch an old man cutting bamboo strips for curtains on the footpath, while stuck in Bengaluru's notorious traffic jams - a good 10+ mins without moving an inch.

and I just wanted to try my hand at it and got hold of some youngish bamboo....and made myself two knives( actually completed the one with shoe lace handle(4mm) after 22years - and the other with the PVC tube handle(6mm) in a day.....a fair amount of bellowing, holding, hammering, quenching, and all of grinding and honing was done by self. The blue sheath is a pvc tube again, moulded using the heatgun- check the belt clip)....so what does this have to do with working with bamboo ?

you need a heavy knife with a thick blade and a sharp tempered edge ! the NT cutter is dangerous for bamboo ! the old man just made a notch, split it and ran his blade right through, prying a bit at the knots !

and - avoid using CA if you can - it makes bamboo brittle !

... I just wanted to show off my knives  

Great knives - you made them yourself ?  What metal did you use ?

Just a piece of information/tip for those interested in making their own knives -

use old leaf springs from heavy vehicles - known as "spring patti " locally.

The original Maruti 800 - (japanese one) had leaf springs of excellent quality

@ saikat.....glad you enjoy making knives.....have shared some youtube links on PM.....quite amazing !

.....finished the wing and quite thrilled with the results....here are some pics.

....the right wing tip was done FIRST and came out better than the left.....although the angle is same on both sides, the kink cant be undone. On the bottom, the curve is quite similar when you run your fingers over it.

learning - use same techniques for both sides - used my palm for the right and a set square for the left - hence the sharp bend.

the foam piece in the blue background is the wing tip filler.

Good going bmblm. intresting.

....thank you!

here are some pics of the progress.....

....notice in the front view.....the LE thickens towards the tips....I have added a 3mmx25mm foam strip sanded so as to give a 'slat' kind of an effect - just like the REAL birds - the wing has an AR of about 6+ bordering on the side of 'high' AR, as far as flying wings are concerned, so I have read.

....with the high propensity to 'Tip Stall' with such type of wing.....as I learnt from my previous build, it made sense to include the wing cuff.

.... it feels really nice to run your fingers underneath the wing, and feel the camber change

......and in the side view, the dented nose is evidence of the several test launches....to get the cg....this has been tricky  

....but fun

....drying after two coats of paint !

........just for the record, I maidend the Fenix this afternoon around 5pm at Hoskote.

my hand-eye coordination right now is less than desirable to do anything meaningful....

I got a video.....but let me give you a blow-by-blow account tomorrow  

the date/time stamp on the video is from 2008....so you will have to ignore that....

let me enjoy the videos 

 

  watch !

 

Long Live Omar Sheriff !!!
He passed away. Featured in todays newspapers...
Well done BMBLB

Quote from: ponappa on July 11, 2015, 10:28:23 AM
Long Live Omar Sheriff !!!
He passed away. Featured in todays newspapers...
Well done BMBLB

....May his Soul rest in peace. I got goosebumps reading this post....
updates follow after sometime.

What happened to the flying bird

here are a few pics of the completed bird.

at 415g RTF, it is un-put-down-able 

notice the slats.....

Maiden Flights:

....I'd have had about 20+ test glides (just bare plane) to get the CG and get a hang of the plane......first without fin and THEN with the fin.
it is un-flyable without the fin with just elevons!! the best glides were about 60-75 feet....gentle, flat....nice !

Once fully rigged, it weighs about 415 g, with a WL of 5.03 oz/sft this is with the 850mAh(68g).

the CG is where it should be and feels quite good in the hand 

Launch 1: 25% throttle, 30% throws. Climbed nicely but no response to control inputs...so cut off and landed gently - insufficient throws AND no reflex, as I learnt.

Launch 2: 45% throws, and set the elevators at 5mm deflection (Up) from neutral and launched at a little more throttle....climbed nicely, but the prop came off.

Launch 3/Flight 1 - 00:30 - 02:35
Launch 4/Flight 2 - 03:05

Summary:

The V-Tail KFm Eagle is a fantastic first "Bird Type Plane" to build and fly - it looks great in the sky....but I wanted something different for my first BTP.....something with a wider flight envelope, and should resemble the flight of a Bird of Prey !

The Fenix dives, climbs, rolls and glides beautifully....the sweep really looks neat when coming in fast and low. As you can see from the videos, its quite stable.

...just listing down some points here:

1. 'Self-designed'
2. Does look and fly like a bird
3. Justifiably uses a subtle yet VERY effective feature of 'Slats'/wing cuffs which are essential to mitigate tip stall, especially for a moderate - high AR(for flying wings). You actually need to fly with and without to know the difference !
4. Explored design/stability concepts like Static Margin and Neutral Point.
5. Actually saw the need for 'Reflex' (I think this is what the upward deflection of Ele is called??)
6. Coro+Foam fusion for durability
7. Curved wing tip - been done with foam before, possibly first in coro   ( here I come, EasyStar)
8. Wing Loading well within range, actually lighter considering coro !!
9. CG arrived at by test glides as the tail feathers push the CG further back than just the wing in addition to using the calc.
10.And a few interesting/simple things for further observation  

Hope you enjoyed this !

 
Ah, so birds can loop...
Given enough power
A fine achievement. Congrats.

loved the flight  superb