Gregor99
Elite Veteran
Location: Western Wa
| Looks like I owe Tony an apology. Doug, thanks for pointing this out. I didn't notice this at first since most of the Esky purple parts are pictured as parts and not the assembled head. But as it turns out, the CNC head retains the original Esky control design for the flybar. Align, CopterX, RC TEK and just about everyone use a see-saw assembly that allows the use of a metal control arm with plastic ball ends.
The Esky design (same as the Blade CP, eck!) replaces the metal pushrod with a plastic loop which goes on either side of the blade grip. This allows them to run without a see-saw assembly. The unfortunate thing that I didn't realize until Doug pointed it is that there is no "Purple Part" replacement for the elongated oval push rod. You have to use the one from the plastic head. Below are a couple shots of the Esky head the Compterx for comparison. The Align head uses the same design as the Copterx.
Here's the Copterx for comparison. Note that Align and CopterX use a low slung flybar where the flybar sits below the main blades. As I recall there is some stability benefit to doing it this way. RC Tek uses the overslung flybar like we are all familiar with. I haven’t seen a good pro/con comparison of the two designs so I’m not sure how much difference it actually makes. For this discussion, the difference does make it hard to compare it to the Esky head. I’ve also added the RC TEK head, with its overslung flybar makes for a slightly easier comparison to the Esky design.
RC Tek
The next question will be, how much better is a metal see-saw vs a plastic "ring like push rod" (Esky's description). Since these are really two different designs, you can't compare the individual parts in a plastic vs metal debate like you can with blade grip, swash plate etc. The Esky design puts the plastic in spot where the force is straight up and down, no twisting or lateral force. The see-saw design puts the force on the part in a twisting motion. A plastic piece wouldn't work as a see-saw because it'd likely bend. Metal is pretty much required there. However plastic does work fine and is plenty rigid as the "ring like push rod". As a test I just tried applying force to my push rods and because they are straight, there's no flexing. In a crash, they may break, which is not a bad thing.
So what's the verdict on the plastic? I'll leave that up to the council and the court of public opinion. For me, I don't mind plastic in this spot. It doesn't look like it could flex enough in-flight that it would cause a performance issue. And it may even help protect the metal in the event of a crash. My issue with the "ring like push rods" is that they go around the blade grips. There are really two issues with this. The first is that you must disconnect them to service the blade grips and feathering shaft. Its minor, but it bothers me. The second is a little worse. The ring like push rods on my plastic head fit tightly around the blade grips. I my opinion it’s a little too tight. Despite having grease between the blade grips and the rings, the movement is not as smooth as I would like. This could improve when the grips are replaced with metal, since plastic metal is smoother than plastic to plastic. I'm also hoping the blade grips are a tad smaller and giving a little more room. All that said, there aren’t enough issues with the plastic or the design that I would put a blue head on. But it does add a small amount of doubt in my mind as to equalness (if you will) of the Esky head to the others. And it gives me one more reason to stick to plastic on the head, at least for everything above the swash.
So there you have it. For me the research was a nice lesson in the different head designs. Apologies go out to Tony, and thanks go out to Doug for pointing this out.
By the way, as I was researching this, I found this site that has illustrated pics and assembly instructions for the CNC head and tail.
Head
http://www.buzzflyer.co.uk/ESKY-CNC...Build-Guide.asp
Tail
http://www.buzzflyer.co.uk/Belt-CP-...embly-Guide.asp |
I just hope tony2Chins doesn't WHACK US!!! Just kiding tony2, The apoligy is Sincere, and it is Great to actually be able to see the three heads side by side for comparison. If tryan get's one, we will really get some honest performance reports on the Purply head.
