Bell/Hiller head for the Axe CP using parts from the Blade CP Pro

Here's a list of what I ordered:

Blade CPP parts:

(1) Bell mixer main blade grip set (EFLH1171)

(1) Bell mixer arm and pushrod set (EFLH1172)

(2) Pitch control link set (EFLH1151)

Axe CP parts:

(2) Axe CP linkage set (HMXE7627)

misc parts:

Esky EK4-0002 carbon fiber blades

[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXG842&P=7]Fourmost Precision Solder Washers[/link] (used as shims to reduce endplay)



The install is a bolt-on procedure except for one little spot. The flybar links. The Blade's grips are wider so they may rub the links. This fix was easy though. I heated the links with a hairdryer and stretched them out. They only had to be tweeked 1 or 2mm to clear.

Next up the link-balls are different sizes. The Axe's are 3.75mm and the Blades are 3.5mm. To remedy this issue I made hybrid links which have an Axe link on one side and a blade link on the other (see pic). I also trimmed the Axe the lower set of links (the links that go from grip to swashplate) down a bit so their dimensions were closer to the fixed links that come with the Blade parts. This may or may not be necessary, but it’s something to be aware of.

Now the installation of the grips. I removed the Axe grips leaving the large hub washers in place. Then I popped out the bearings and installed them in the Blade’s grips. BTW at this point don’t forget to install the brass spacer that comes with the Blade’s grips.

OK now the order of the install on the feathering spindle from the center hub out:

1st stepped washer>the blade grip<2nd stepped washer<a 3mm i.d. Fourmost shim<the Axe’s spindle screw and washer. That’s it!

I went with new blades as well. E-sky EK4-0002 from Heli-Direct, but you can use the stock blades too all you need is some spacers for the wider gap in the Blade’s grips. Extra Axe hub washers (part#HMXE9900) work pretty well.

There is one other thing. It's not a problem, but something to be aware of. The new grips are designed for 3 bearings per side. However you can only use two bearings per side because the Axe's hub is wider than the Blade’s as can be seen in the pics. The reason I bring it up is the bearings come pre-installed in the aluminum grips so I'm not sure if they would work.



The first pic is of a Blade CPP rotorhead, note how much narrower the hub is.
The second pic is of the finished conversion on my Axe. Notice the links connecting the grip to the hub and swashplate.

What does the Bell/Hiller do. How does it help in performance or control. just wondering.

[link=http://www.rcgroups.com/forums/showpost.php?p=7846666&postcount=3426]Here's a link[/link] to some info I posted a while back on the subject.

So basically it's just that little link from the swashplate to the flybar carrier? So what's the flybar do in a Bell-Hiller setup? Add gyroscopic stability?

Kinda, yes. It connects cyclic control, directly to the swashplate instead of going through the flybar first. This decreases cyclic response time giving the pilot quicker control.


The flybar does the same thing it does in a Hiller set-up. It helps to stabilize the heli. It's only the responses to cyclic stick inputs that change. Since they become faster many think helis with B/H heads are harder to fly.

i did the conversion. YES, it is harder to fly. i had hover down solid and then was all over the place after the mod. BUT, now I really enjoy the responsiveness of it. fly my buddies stock axe every now and then and it just isn't as fun. plus i don't think you can do the 3D flight as well without the mod imo.

That's true to an extent. Some 3D can be done. Rolls and inverted flight and maybe even a loop can be done with a Hiller head. More aggressive 3D such as funnels and flips would need the more responsive B/H head.