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FTFC20 Wind Freak designed by FoamyDM

FoamyDM

Building Fool-Flying Noob
#1


Original Post on outerzone: https://outerzone.co.uk/plan_details.asp?ID=5725
Selection
I chose this because the slight curve and Alula-like look caught my eye, and I wanted a plan that I could record a How I go from Inspiration to Full DTFB Plan. and I didn't want that to go longer than 1 hr.
The Basic Wing shape is a shallow Clark-Y wing foil. Being nearly entirely wing, the Incident angle is largely irrelaevent I believe. On this Craft, (like most wings) correct C.G. is critical. This plane is important to note the slight upward washout at the wing tips.
Plans & Preliminary Wing Loading:
CADDpgimage.PNG WFWingloading.PNG
Build Instruction/Notes:
Starting viewpoint - This craft has a Gently up-curved outer wing. the trick here will be adding strategic locations of Paper removal.
Pulled Highlights from the BLOG Below

Takeaways: Stop, Start Continue

Maiden Flight Vid:
Reserved
 

Attachments

FoamyDM

Building Fool-Flying Noob
#5
I Started Cutting last night
IMG_20191028_074704822.jpg
Cut out, trimmed and paper removed.
IMG_20191029_004748798.jpg
Trailing edges tapered with and iron on cotton, placed at/near the edge of the board.
IMG_20191029_005423992.jpg
Next step is to assemble the foldover support and get weights to keep it there while the glue sets.
 

FoamyDM

Building Fool-Flying Noob
#6
Small progress last night, but progress none-the-less
IMG_20191029_214535651.jpg
You can see I used the scrap curve from the spars. Only one side is needed. Pay attention to keeping the ends even. Otherwise the wing will glue-up warped. I just cut 1x3" pieces from scrap, for the spacers.
 

FoamyDM

Building Fool-Flying Noob
#7
I had some time and managed to finish this last night. At least for a glide test.
IMG_20191030_194649243.jpg
To get the curve, I glued in the spars inner bottomed half. Let that cool. Then I glued the outer bottom, the front edge, and top of both spars, then filed the wing over and weighed it down on the support. Like so:
IMG_20191030_194913069.jpg
When fully cooled - minutes. When complete I noticed the curve sprung back by about half. Oh, note where I put score lines on the inside (50%, 65% 80%) and removed strips of the top paper about a 1/8" wide, to relieve the compression. Trim any spare ends to the 45° end treatment and glue on the edge fins.

It was time for the fuse.
Basic 4 panel construction. I trimmed the inside rear of each side panel to accommodate the rear fin. Please note, this space is thin! You cannot fit much. I also added an extra piece of faom on the rear trapezoid at the fin to build up the height to match the wing. This did two things. 1 provides better air flow, give a surface for friction fitting the wing in. Lastly the very. Stab was flimsy, and reinforce on each side with a 1/2 length of bbq skewer imbeded in the side panel 1/4".

I had to adjust the control surfaces by approx. 1/4" each to accommodate the fuse width. Now all that was left to test it.
IMG_20191030_235459818.jpg IMG_20191030_235420627.jpg IMG_20191030_235411070.jpg
Looking good.
IMG_20191030_235446930.jpg

Testing
This portion went poorly. I flew it once for fun without nose weight. And it fluttered back-flipping to the ground. As expected it is a very tail heavy wing. So I started adding weight.
And more weight
And more weight.
I have nearly $2.50 in nickels pennies and quarters (8each) dumpped in the nose just to get it close. The CG marked is just in front of the front spar.
When given a moderate toss it would fly for about 20' then nose in -HARD. It's good I taped the fuse bottom and nose to protect against nightly dew. I had 1 toss the was about 50' before nosing down.
At one point I attached a steel drilling tooth to the bottom at the wing front. (I think it weighs 1 lbs) just to balance it.

I had a similar difficulty with the Alula clone.
I stopped when cracking the fuse in half a second time with little glide success.

Possible Sources for Adjustment
I checked the wing airfoil, and I don't have any reflex built in like the section prescribes

I'll try and get footage
 

FoamyDM

Building Fool-Flying Noob
#8
Had a thought about this build coming up to the weekend, but couldn't try it until yesterday in the dark.
Idea; Mount a long stick so I can fine tune the CG weight location easier. Smaller weight on a longer moment arm means a large window for balance.

I have a 59" broom-handle-turned-walking-stick (~1.3#/600g) that I rubber banded on. Balanced out and found the perfect spot, first try. about 2/3 down the stick. It turned out, the CG was at the marked CG holes.
Figure that?:unsure:
IMG_20191103_194726024.jpg
:giggle: but it is ONLY there. Stray an 1/8" (2-3mm) and nope. I tried many things. This was after I manually curled the TE up. (It crinkled the paper.:cautious:) however it flew. Flew nice too. When from the sidewalk at the porch to the ditch at the street. It was too dark for video. So I will try to get a shot tomorrow morning.

It is a TIGHT window. As a little nose heavy and it lawn darts. To far back and the porpoise, stalls and stabs vertically in to the dirt.
the trick is now, is how to make a FUSE that is long enough to balance the wing, but make it usable.

Here are my ideas;
1. Put a motor and big battery up there. (I'm thinking 8" folding prop. with a b-pack level motor)
2. Cut out large-ish holes in rear half of the wing and rudder, then cover with cello wrap.
3. Lengthen the Fuse by 6"
4. Do a combo!

What do you think?
 
Last edited:

FoamyDM

Building Fool-Flying Noob
#9
After getting out the ruler. I have a few corrections to the broom handle information.
1. The length is 48"
IMG_20191104_181501289.jpg
2. The balance mark is 25.5" from the front. OR the center of mass of the broom stick is 1.5" for. C.G. IMG_20191104_181456742.jpg
3. The handle weighs much less than I originally thought, 365g (~8oz.)
IMG_20191104_181744048.jpg

This means, I need a fuse with a net moment of 547.5 inch-grams. With a fuse CM 6" in front of the plane/wing C.G, I need it to have a mass of 91.2g. This is doable with a battery.