Eury
rrProfessor
Location: Ankeny, IA, USA.
| BuiltOK, it's built with the exception of gluing the boom supports, linkages and electronics setup.
The Head
The head is pretty standard, it uses mixing arms on the grips, like an Xcell, Century, and any number of other helis. I'll document this in the order it is built.
Swash and Washout
First the swash is assembled, it's a very nice unit, nice and smooth with no play in it. It came pre assembled, but all the balls and screws needed to be locktited, as there was none from the factory.
Next up is the washout unit. Again, pretty standard stuff, black anodized metal block with black anodized arms. The arms ride on bearings, however, there is binding when tightening the bolts all the way up, so they had to be backed out a bit and are relying on locktite to hold them on. One VERY nice feature here is how the pins that hold the washout links to the arms are retained, the arms have a set screw that engages the pin. Awesome design there, much better than clips or the friction fit that so many other helis use. One concern I have in this area is the anodizing inside the part. I see that wearing over a short period of time and increasing the tolerances. As it is, the washout has no play on the mainshaft, and is very smooth. I have a feeling it's going to get a bit sloppy on the mainshaft over time. The instructions then have you place the swash and washout on the mainshaft in preparation for the head. The antirotation pin and guide are a very good fit with almost no play between them.
  
Head Block, Grips
Fairly standard stuff here. The head uses 2 O-rings on each side that fit into the head to provide dampening. I've provided a picture of the grip with the bearings and spacers assembled on the spindle, basically the same design as every heli you've seen, which is good because it's proven, and works well. The mixing arm mounts are a separate part from the grip itself and bolt on, then the mixing arms themselves.
Here's where I ran into more difficulties. The mixing arms have 2 bearings in them, but they do not seem to have any flanges or spacers inside to keep the bearings seperate, instead they rely entirely on locktite to keep them in place. I did a little research and looked at pics on the QWW site and elsewhere, and it seems that the standard practice on these is to assemble them so the outside bearing ends up inside the arm butted up against the inside bearing. I'm not a huge fan of this, with the bearings out at the ends retained properly, the arm is well supported and has less of a lever effect on it. It's probably not going to cause issues, but I'm not a fan of it. Where the problem is on the one I put together is in binding. First, it calls for 2 spacers (a 3x5x1 and a 3x5x3) between the arm and the grip, all held on with a 3x14mm screw. Sounds fine, unfortunately there are no 3x14mm screws in the hardware kit. Dropping it down to a single spacer allows the use of one of the provided screws, but nothing I could do short of backing the screw out slightly with make the arms move smoothly. The issue is with the spacers and the bearings loading on each other. Any tension on that screw either freezes the arms in place, or just makes them very hard to turn, and as the screw is backed out the arms get notchy, then finally smooth. It can be used like this, as long as you have faith in locktite holding it with no torque on the bolt. Personally, I don't have that faith. This could be solved with correct use of spacers and shims, but not with what is provided in the kit.
Next up is putting the pins into the bottom of the headblock. This is a great idea, the pins screw in rather than being pressed like so many others, allowing replacement.
  
Flybar cage/assembly
The flybar rides in a seesaw through the center of the head, and is supported by a fully enclosed flybar cage. As mentioned before, the bearings in the side of the block that the seesaw pivots on are not shielded, I would like to see them shielded. The seesaw has a nice smooth movement with no binding. The instructions never indicate when or what balls to attach to the side of the seesaw, so I guessed based on pictures and put a set of the shorter balls in at this point. There are matching holes on either side of the seesaw, which works well, but it would have been nice for QWW to put the holes staggered on opposite sides so we could have some options as far as flybar inputs.
I said it at the beginning, and I'll say it again, I like the Flybar cage. Actually, I like it even more now, I didn't notice before how it separates in the middle with no screws for ease of installation. I really like the design of this part. On installing the flbar and cage to the head, I discovered that there is a huge variance between the width of the seesaw and the cage (as seen in the picture). The instructions don't indicate that it should be there, or how to deal with it. Looking around, I had 4 brass spacers left over from a previous assembly that fit in there and took up most of the gap. However, there is still a small amount of play there that can't be taken out with the provided hardware. A shim kit sure would be nice here. The instructions also don't mention mounting the ball links to the flybar cage, so if you don't anticipate it and install them at this point, you're going to be pulling the assembly apart again in a few steps. Luckily I anticipated it, and made up a link to the proper size and installed it. (they provide lengths later in the manual, although they don't tell you what size rod ends to use, there's 2 sizes. Bizarre.)
   
Center up the flybar, and tighten up the SHCS on each side of the cage, and the flybar assembly is done, and the head is ready to be bolted on. The instructions here call for a 3x14mm SHCS, and I used the one pictured.
Anyone see a problem? That's right, it's not a shouldered bolt. This NEEDS to be a shouldered bolt. Digging around the hardware kit, there isn't a usable replacement. All of the shouldered bolts have the shoulder too long, and everything else is simply threaded the whole length. If you buy one of these helis, DO NOT use this bolt, it will shear at some point, the threads are not capable of handling the loads that are being imposed on it.
Assembled
The heli is now all built after bolting on the boom and fins. All that is left is making up linkages to the proper sizes, assembling the boom supports with the provided carbon rods and aluminum ends and installing the electronics.
 
I've took a couple of pictures that help you get an idea of the size. The heli with the red TT paddles is a Predator Carbon Gasser with a G231 in it. As you can see, the OD 20 is slightly shorter in length, and slightly taller in height. The width of the 2 is comparable. Next up is comparing the size to something everyone is familiar with, a 600N. There really is no comparison, the OD is much larger in every dimension, and with no electronics in it beyond the 3 cyclic servos, and no pipe, it weighs more than the 600N does RTF without canopy as seen.
Predator comparison
  
600N comparison
 
This last pic is maybe the most interesting of all. This is a pic of all the hardware I have left over. Granted, I still need to install the blades, canopy and boom supports, but I have about 2 pounds worth of screws left. The problem of missing hardware isn't because I didn't get enough, I got enough to build 4 helis, I just didn't get all of the right sizes.
I'm thinking about a conclusion to write on the mechanics, I'll get to it before the end of the day, I just have to decide how to put it.
Nick Crego
I swear to God, I'll pistol whip the next guy that says Shenanigans |
That's not correct, that takes some pretty good loads, and will fail, resulting in a very fun auto, or a large repair bill. After the build is complete, if there is an extra long link like that in the parts box, I will replace it, as the rest of the long balls have about 2mm worth of threads, assuming it won't foul the center section of the slider.
I do really like that aspect of the head.
