One More Thing to Worry About on My Maiden

[eltreato]

Backstory: I am just finishing converting a 500 from FB to FBL that I purchased used recently.

Problem: So I bought FBL head from Helidirect installed it, installed servos, I have no idea what servos or size he was running before me. I got it all setup and noticed something that looks like will become a problem. The aluminum head has two prongs on either side that jut down about half an inch and are to guide the plastic follower plate from the FBL kit. My problem is that when I give 12 degrees of negative pitch the follower plate looks like it's about 1.5mm from sliding off the end of these rods getting me stuck in a negative pitch state resulting in a crash. Now it looks like I will have to lengthen my servo links by 1.5mm and shorten my swash links by the same length. I was silly to think that I could just use the same length links as used with the flybarred setup. I could completely see this taking down a heli for someone who didn't catch it, especially give the lack of documentation that came with the FBL head assembly.

That's all!

[dr dremel]

Isn´t the washout hub (follower plate) supposed to be screwed down to the main shaft, flush against the head block when converting to FBL? At least that´s how it is with the Mini Protos (my Protos is still FB).

[eltreato]

That would make sense wouldn't it? The more I thought about it, the crazier it seemed to me that it would float up and down as the follower arms moved. There is one, maybe two small holes in the plate where a screw could go, but I'm pretty sure no holes in the main shaft for a bolt to hold it in place. Perhaps it is meant to be bolted on with a bolt that pushes up against the man shaft hard enough to keep it from moving. I need to look into this.

[alexf1852]

It's a little confusing. You said you bought the FBL head but your description seems like you have the stock FB head with a FBL conversion kit. Those two pins on the main head are only on the stock FB head. That plastic piece (washout hub?) you describe with the follower arms screwed on and slides up and down on the two vertical pins, has a set screw hole on one of the sides. You need to push the hub all the way up against the head and slightly tighten the set screw. But be careful not to apply too much pressure to tightening the set screw, or you will strip the washout hub. Just light finger tight is enough. Test by lightly trying to pull the washout hub down with your fingers.

Also, there is a manual for the FBL conversion kit on MSH's site. You don't normally have to change the servo rod lengths. But it might have been on the low side from the previous owner. I would check them against the manual. I think the stock measurement is about 28mm.

[alexf1852]

After checking the MSH site, I remember that MSH never made a manual for the new version of the FBL conversion kit. You can look at the manual for the mini Protos starting at page 23 to see how the new fbl conversion goes together. But bottom line is you need to tighten that set screw on the side of the washout hub. If there isn't one in there, then it should have come with the conversion kit.

[corrosionate]

The plastic follower block that slides on the two shiny pins SHOULD be anchored to the main shaft with a grub screw and should butt right up against the bottom of the head block and stay there. The FBL comversion kit comes with the plastic piece that's already drilled for the grub screw ( or at least it did a few years ago), but when I broke mine, I simply grabbed the one from my flybar parts and drilled a hole in it. Found a small grub screw and screwed it in there snug. Don't over-tighten.... But it looks identical to the correct fbl piece and has gone hundreds of flights with no issues for me.

Not sure how the newer kits are set up...

Sounds like I'm saying the same as the last couple posts, but yeah, the FB hub would float, the FBL hub needs to stay put. If you don't have one with a hole and grub screw in it, you can drill the one you've got.


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[eltreato]

Thanks guys, it sounds like I'm missing a set screw/grub screw. I didn't see one when I built the head. I will go through my pile of leftovers from the flybarred head to see if it somehow ended up in there.

All the best!

[eltreato]

Well if I ever had a grub screw it is long gone. Fortunately I found one off the pinion of a long since replaced 450x motor. It's a bit short, but gives enough bite on the plastic plate and main shaft. Even if it does fail, by adjusting all my links by 1.5mm the plate could conceivable still travel on the main shaft without sliding off the pins from the head.

Thanks everyone for your helpful input on this issue. I will be reviewing my pitch setup one last time given these changes and hope to do my first flight this weekend.

All the best.

[Mikej]

If you are converting from FB you will probably have some grub screws holding the flybar in place that you could use...

[eltreato]

Good point Mike. You know I have a bag of all the parts leftover from the FB head, but the flybar itself isn't in there as the bag is too small, I'll check on it, thanks for the suggestion.b

[eltreato]

Just to follow-up I got the maiden flight in today, it was uneventful, just the way I like them. I was running at 80% flat curve and wasn't impressed by the power in this heli so I will crank it up for my next flight. I suspect the belt may be a bit tight robbing me of some power. Other than that I am really pleased with this heli.