550X Swash Design

[IndividualWon]

Any idea why Align moved back to control arms above the swash on the 550X, instead of the direct to main blade grip arm like on the 550L?

[rhodesengr]

Just a general trend away from the DFC head. There are a large number of threads discussing the pro and cons of DFC vs swash follower type heads. For most, it probably doesn't make much of a difference. DFC is more likely to strip servo gears in a crash.
Here is one picked at random
https://www.helifreak.com/showthread.php?t=752146
and a good article on the topic
http://www.rchelicopterfun.com/DFC.html

[IndividualWon]

Originally Posted by rhodesengr

Just a general trend away from the DFC head. There are a large number of threads discussing the pro and cons of DFC vs swash follower type heads. For most, it probably doesn't make much of a difference. DFC is more likely to strip servo gears in a crash.
Here is one picked at random
https://www.helifreak.com/showthread.php?t=752146
and a good article on the topic
http://www.rchelicopterfun.com/DFC.html

Interesting reads; thx!

[Thestructured]

Basically so that people who complain about DFC can't complain about Align using DFC anymore.

Quality servos are unlikely to get stripped very easily even with a dfc head, and a traditional follower design does not ensure that you won't strip gears.

It's just personal preference but nobody really complains about a traditional head setup.

[bad007]

More direct feel, DFC = lower disc. Got DFC on all.

[rhodesengr]

Originally Posted by Thestructured

Quality servos are unlikely to get stripped very easily even with a dfc head, and a traditional follower design does not ensure that you won't strip gears.

I have bad crashes where nothing happens to the servos and mild crashes where the strip. I don't crash much anymore unless I have some sort of mid air failure. My last crash was a 700N DFC gasser conversion. It crashed because a tail blade flew off dues to a failed screw. Two cyclic servos stripped even though the crash was pretty mild. Main blades didn't even break.

[IndividualWon]

Not knowing ANYTHING about engineering; I would think from a balance perspective... The DFC design could create vibration that the radius arm design might not. Not that any of us would notice, but the DFC arms are away from the main shaft; if either of those DFC arms are grams heavier than the other.. Vibration. Thoughts?

[bad007]

Originally Posted by IndividualWon

Not knowing ANYTHING about engineering; I would think from a balance perspective... The DFC design could create vibration that the radius arm design might not. Not that any of us would notice, but the DFC arms are away from the main shaft; if either of those DFC arms are grams heavier than the other.. Vibration. Thoughts?

No vibration, the exact opposite , the radius arms are always being flexed at the joints, get sloppy and also can affect phasing. The grips on a DFC head have to be in real bad shape to alter anything. Besides I weight every part in head assy., piece by piece, measure thrust bearings with shims to match and then balance the entire head assy as a unit. Getting the disc closer to the mass makes for better agility. My 500l will get the DFC upgrade like my V1 550 and 500ESP this spring.

[Smoggie]

The head on the new 'conventional' flybarless head on the 700X is exactly the same height as the old DFC head... So there can be no advantage claimed on that score.

The potential downside of DFC are explained on the previous link: http://www.rchelicopterfun.com/DFC.html

With DFC phasing IS effected if there is any teetering of the feathering shaft, this is an inherent and unavoidable design constraint of the DFC concept. With DFC you have to use rock hard dampers to minimise this effect, and you need to keep your dampers and head bearings absolutely play free. Even so DFC does tend to wear the ball links on the bottom of the arms more than a conventional head.
The heavier DFC arms used to be prone to being thrown off the bottom balls at high RPM due to centrifugal force, but the newer style DFC swash with balls mounted tangentially solved that problem.

The direct feel that some enjoy isn't actually due to the DFC, it's due to the rigid dampers that DFC heads are forced to use. You get the same feel by running rigid dampers in a conventional head.

[bad007]

Originally Posted by Grumpy_Old_Man

The direct feel that some enjoy isn't actually due to the DFC, it's due to the rigid dampers that DFC heads are forced to use. You get the same feel by running rigid dampers in a conventional head.

Not sure, I always run hard TB Greens way B4 DFC came out. I also cut down the man shafts at bit to lower the disc to make it more responsive to cyclic input and it did make a difference. The swash followers seamed to always throw the phasing out over time as they developed slop. The DFC let the head get lowered even more and made another improvement in response. DFC Pros and Cons has been kicked around for a long time. First hand back to back comparison taking all of my original FBL heads to DFC, esp. my V1 550 that always had phasing issues I could not correct and flew for years, installing the DFC head made a night and day difference in agility. The phasing issue did go away to boot.
DFC is giving you the ability to lower the disc even more and increase handling. Remember how high original FBL head set? Pretty high and have since been lowered. Back then FBL elev bobble was a common complaint, not anymore and all due to lowering the head assy. My 500L will get the DFC and that's just to lower it about
8-10mm