I finally decided to "bite the bullet" and get the new 8mm head. As usual, Rusty's customer service was top notch and shipping was fast. I ordered it on Friday and had it in my hands by Monday.
While there are no instructions with the new head, building it is exactly the same as the 6mm head. The only difference are the dampeners. As most know, the new 8mm head uses 2 o-rings for dampening instead of the current style.
The o-rings are a little harder to put in. Here's what I did. After I had both o-rings properly seated in the head, I lubed them generously with some silicone grease (I use dielectric grease from Autozone - used on spark plugs). I then pushed the 8mm spindle through one side. Once the spindle was through one side, I put the other side against a block of wood and used it to hold the o-rings in while I pushed the spindle through.
After assembling the head, it did feel a little on the stiff side. This can be attributed to the new o-rings with stiffer dampening. To my surprise, the bolts for the flybar carrier are now 4mm. The seesaw itself is slightly thicker so the the 4mm bolts have more threads to "grab" onto. I chose to use some spare 4mm spindle black oxide bolts instead of the stainless bolts that are included. I just used my dremel and removed about 2 threads from the end of each bolt and that turned out to be the perfect length. I also used red loctite to secure the 4mm seesaw bolts to the seesaw.
The 8mm head is also a bit heavier. With the 6mm head, my X50 tipped the scales at 7lbs 10oz. With no changes other than the new 8mm head, my X50 now weighs 7lbs 13oz. Because of the added weight up top, I decided to order some 4mm Superstubz to use with the new head. The Superstubz are only 12g each compared to 23g for each of the 95mm V-paddles that I have been using.
As other have stated, the short links need to be shortened. I ended up using some slightly shorter threaded links I had in my box and then cut about 1-2 mm from the end of each plastic link. Then I reassembled the short links. With the mixing arm parallel to the grip arm, the short links ended up at about 24.65mm each (measured with my digital calipers). I then adjusted teh long links from the swash until the blades were at zero pitch at mid stick. No other adjustments were needed. I ended up with +/- 12.5 on the collective and +/- 8.5 cyclic (same setup as the 6mm head) without any binding.
At the field I switched out my 95mm V-paddles for some 4mm Superstubz. I also double-checked all the settings. Once everything was rechecked and the Superstubz aligned, I fueled her up.
I picked her up in normal mode (1750 rpm) and I notice a slight wobble. I checked all the surfaces and then flipped the switch into Idle Up 2 (2150 rpm). The wobble went away and she was hovering perfectly. Because I took my time zeroing out the blades on the bench, the tracking was dead on.
I flew a couple of circuits and she felt very good. She tracked straight as an arrow in FFF and turns were easy and predictable. I brought her back in front of me. I proceeded to do some pitch pumps. Damn is this new head responsive! I then brought her up a little and proceeded to do some stationary flips and rolls. Flips and rolls were not only perfect, but they were very quick. The Superstubz proved to be a perfect match for the new 8mm head.
This head is ultra responsive. It feels even more connected than the 6mm head. I was a little worried about the overall stiffness of the head when I first built it. But after the first flight everything started to loosen up nicely. The wobble that I experienced on the first flight, were gone by the time I finished the first tank of fuel.
Autos were very nice. I thought I would have a little wobble toward the end, but there was none. The first flight ended in an unintentional auto because I ran out of fuel. I was having so much fun flying and tossing my X50 around that I neglected to check the fuel level...LOL
I ended the 2nd flight with a nice high (about 200-300 ft) auto. The new head is very predictable during an auto. It is very easy to hear the headspeed decay as you near the end of your autos.
Overall I am Xtremely (pun intended) impressed with the new head. Although it is "beefier" and heavier than the 6mm head, I did not notice the extra weight in the air. She still felt very light. Response is amazing. The machining was absolutely perfect. There were no marks anywhere and everything lined up perfectly. I highly recommend the 8mm option to anyone thinking about it. There is nothing wrong with the 6mm head, but the 8mm head definitely feels more responsive.
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