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Symmetrical wing Bloody Wonder

stay-fun

Helicopter addict
#1
Hi guys!

Here's my version, my modification to the Bloody Wonder! I've had a couple of planes, but the bloody wonder is the one I liked most of all of them! There were only 2 things I needed to change: I wanted a rudder, and a symmetrical wing. The rudder mod is already on this forum, and I've done the exact same as Bolvon72 did. The reason why I wanted rudder is that I can do coordinated turns. A symmetrical wing improves inverted flight handling, less forward pressure on the elevator stick would be needed.

Things that this plane can do after my mod:
- inverted flight with only little to no forward pressure on elevator
- knife edge flight
- flat turns (without bank)
- super tight loops and rolls (the 'regular' BW can do that, too)

Things that this plane can probably do:
- hover
- a whole lot more that I don't have the skills for :D

Making the wing


IMG_20140519_193520 (1280x960).jpg

(please note the wing is up side down here)

The reason for wanting a symmetrical wing is to fly inverted with less forward pressure on the elevator stick.

I started with making the wing. I took the dimensions of the original bloody wonder, but make it symmetrical using drawings of the FT 3D (which has a symmetrical wing also). I kept the distance from the leading edge to the spar the same, and also the thickness of the wing is the same. Only now, there are only score cuts at the leading edge, the front and end of the spar.


IMG_20140617_205236 (1280x960).jpg
(all dimensions in centimeters)

I highly recommend to draw a line for the leading edge on the back side of the foam board, in the middle 5 cm. I didn't do it, but it'll become very handy later on to align it with the fuselage.

The tail (horizontal stabilizer) needs to be added to the wing. I refer to the bloody wonder build video for how to do that.



Making the fuselage

I decided to let the bottom half of the wing 'sink in' the fuselage. So a part of the fuselage needs to be removed. In order to do this, I put the wing on the fuselage, and made marks where the leading edge, trailing edge, and the edges of the spar are. The whole wing is thickest at the spar, total thickness is 4 foam thicknesses (2 cm), so at the spar I need to cut 1 cm out. I drew a line, and connected those to the leading and trailing edge, and cut it out:

IMG_20140519_203939 (1280x960).jpg

IMG_20140519_204243 (1280x960).jpg



Joining the wing and the fuselage

Alright, that was the easy part. Now, the wing has to be joined with the fuselage! This is a little tricky. First of all, at the middle part of the trailing edge of the wing, there needs to be a score cut, so the horizontal stabilizer can be perfectly horizontal, and the symmetrical wing also. The score cut is exactly between the aileron score cuts. If you don't do this, the symmetrical wing will not be lined up properly!


IMG_20140519_204309 (1280x960).jpg
Wrongly aligned wing, without score cut!! Note the gap behind the wing!


IMG_20140519_204525 (1280x960).jpg
This is the wing with score cut to the horizontal stabilizer. In the picture it's up side down (you're looking at the bottom of the wing)


IMG_20140519_204619 (1280x960).jpg
Wing and tail/horizontal stabilizer correctly placed on top of the fuselage. As you can see I haven't bevel-cut the ailerons yet, and that makes the importance of the score cut in the middle of the wing very visible.

Now, to glue the wing in place. First I glued the horizontal stabilizer to the fuselage, making sure everything is nice and square. Due to the score cut at the trailing edge, the wing itself can bend over completely (as shown in one of the pics below). Now, push the wing down. Here I noticed that it may be pretty difficult to make the wing flush with the fuse! So what I recommend, is to use the line you drew at the leading edge, and use that to make it perfectly align with the fuselage, so it isn't crooked. It is not in the picture, I found this out at the time I was lining up the wing. I think I got kinda lucky and it worked out nice.


IMG_20140519_205426 (1280x960).jpg
The wing attached to the fuselage, with only the horizontal stabilizer glued.


IMG_20140519_204626 (1280x960).jpg
It is best to put 2 dabs of hot glue onto the fuselage where the spar is going to sit in, then lowering the wing into it, making sure the leading edge is parallel to the top fuselage (use the leading edge line you drew, which I didn't...). When dried (or cooled down, since it's hot glue), fill up the entire space between the fuselage and the wing with hot glue for a strong bond. Then add the rear part of the fuselage, as Josh describes in the bloody wonder build video.


IMG_20140519_210758 (1280x960).jpg
And now you have a symmetrical wing!



The power pod

There is one more complication... The power pod! Since the wing sinks in the fuselage, we also need to remove some from the power pod to make this fit. Not a big deal.

IMG_20140601_130515 (1280x960).jpg

Side note: one thing you'll notice is that my power pod is slightly taller than the standard version. This is because I wish to fit my battery inside it, rather than on the outside. I'm running 1300 mAh 4s packs, and they're pretty tall so I needed to make room.

I made sure with the pod that I don't take foam away from the very rear part of the pod, and the very rear part of the pod needs to extend beyond the symmetrical wing. This way, you will be sure your motor isn't at an angle.

I don't intend to describe how to make the ailerons work and the rudder, you can find this perfectly in the bloody wonder build video, and Bolvon72's rudder wonder article.



IMG_20140531_222643 (1280x960).jpg

Final edits

I was flying it and loved it! One thing I still couldn't pull off, was a decent knife edge. At first I wasn't sure if it were my limited skills, or the plane. Then I got a tip from a friend, to make winglets! The vertical stabilizer/rudder is so big, that in knife-edge the front of the plane just drops too much (which I was experiencing). So I installed winglets. I made them in a waterdrop-shape, 17cm long, 10cm high, and the maximum height at 5cm behind the leading edge. They're still a bit on the small side, but they do the job very well! Looking back, it would have probably been cooler to make the winglets the same shape as the vertical stabilizers. I'll do that after a crash that requires a rebuild. For now, I'm soooo much enjoying my new plane! It definitely is my current favorite! :):):)

IMG_20140601_113111 (1280x960).jpg IMG_20140601_113122 (1280x960).jpg IMG_20140618_073330 (1280x960).jpg



The power setup I use:

- metal geared turnigy servos (I managed to strip the elevator servo in flight in my standard bloody wonder)
- OrangeRX 6ch receiver
- Align 35A ESC (overkill, but I had it lying around)
- [NTM propdrive 28-26a, 1200 kV with an 8x6 prop.] Now replaced by Sunnysky 2216 1200 kV.
- Turnigy nanotech 4s 1300 mAh lipo.

Note that I live at 1.5 km elevation, and typically we need higher pitched props to offset the lower air density, compared to sea level.

Annnnnd here's the long awaited video!



(I know, not too much inverted yet... I'm still learning ;) )