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HomeAircraftHelicopterHelicopter Main Discussion › DFC link giving in
05-25-2015 08:51 PM  3 years agoPost 1
rudyy

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E. Amherst, NY

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If one DFC link gives in, will you still be able to have cyclic control to certain extent with the remaining DFC link to one of the main blades or you are completely done with it?

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05-25-2015 08:59 PM  3 years agoPost 2
Dr.Ben

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Richmond, VA, USA

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The remaining link will drive the swash inner ring. What happens next is contingent on whether the disconnected blade feathers itself or severely lead/lags. If the former you might make it down. If the latter it'll be a kaboom because you'll likely have a boom strike in flight.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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05-25-2015 09:04 PM  3 years agoPost 3
Aaron29

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USA

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You aren't planning this any time soon, I hope, Rudy?

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05-25-2015 09:07 PM  3 years agoPost 4
kthane

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Pensacola

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Most likely thing to happen is the heli going off like a shotgun.

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05-25-2015 09:11 PM  3 years agoPost 5
rudyy

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E. Amherst, NY

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I am trying to figure out what is causing the crash of my 700N this morning. The last thing I remembered is the heli just acted weirdly all of the sudden with the cyclic and I immediately hit throttle hold. The heli still crashed but the extent of the damage was reduced. The only clue I have is the broken DFC rod end, but with Dr.Ben's explanation, it was caused by the crash itself.

I examined all the servos on the bench and nothing is stripped, and I shook all the wires and nothing was loosened or disconnected.

So, it remains a mystery to me.

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05-25-2015 09:30 PM  3 years agoPost 6
don s

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Chesapeake, VA

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What is "weirdly"?

I had a link go one time and I heard a poofy fluttering sound. Almost nailed the auto too, almost.

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

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05-25-2015 09:32 PM  3 years agoPost 7
kthane

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Pensacola

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Well, it was probably not a dfc link letting go as that looks something like this:

Watch at YouTube

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05-25-2015 10:12 PM  3 years agoPost 8
BobOD

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New York- USA

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Not always. Sometimes the disconnected blade will remain stable and the heli gets mushy feeling with occasional jerkiness.
But, it's a bomb ready to go off.

Team POP Secret

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05-26-2015 05:07 AM  3 years agoPost 9
dkshema

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Cedar Rapids, IA

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I lost a pitch link quite a few years ago on a Hirobo Freya. Right after takeoff about 15 feet off the ground. The heli pretty much exploded in flight. Boom strike and that was all she wrote. Guess I didn't get that lucky feathering thing.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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05-26-2015 12:04 PM  3 years agoPost 10
Cobra 46

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Cambridge il usa

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I had a link come off my FB X-cell one time it didn't exploed. It just had very little control. It landed in the side of a tree, Man did that make some noise !!!!! Got it out looked it over,
New link and back in the air !!

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05-26-2015 12:46 PM  3 years agoPost 11
dchekas

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Farmington, CT

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I've witnessned the DFC links pop off several times in a row mid flight on a 700E.

The reason was the pilot had the wrong dampers installed (85 Duro rubber instead of the hard plastic they require).

While it made a very distinct noise, he was able to land the model every time.

Not every case may get this lucky, but a popped link doesn't always spell instant doom.

Team Align, Team Futaba, Team Byron Fuels, Team Thunder Power

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05-26-2015 02:16 PM  3 years agoPost 12
Cobra 46

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Cambridge il usa

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It might have somthing to do with how tight the blade are on the head .

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05-26-2015 02:21 PM  3 years agoPost 13
fastflyer20

rrKey Veteran

N. Tonawanda, NY

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Sorry to hear that Rudy, I wish you waited until I got to the field before you crashed....

Tom
CAUTION - my posts are based on my experiences, yours may be different.

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05-26-2015 05:38 PM  3 years agoPost 14
Aaron29

rrProfessor

USA

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It sounds like maybe a FBL sensor and the link died in the crash.

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05-26-2015 05:51 PM  3 years agoPost 15
oldfart

rrProfessor

Vancouver, Canada

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When a pitch control link pops off, or breaks, the possibility of a boom strike depends on the design of the rotor blade. If the blade design is one in which the chordwise CG is located where it will result in a neutral pitch stability, then the blade will feather at 0 pitch and one will still have full control of the other blade. This will usually mean the heli will still be controlable, but with much less maneuverability.

If the blade has a chordwise CG that results in it leading or lagging in flight, then it will not feather and will rotate in the grip and take out the boom.

This is why, when a link breaks or pops off, some helix will not have an "in air" boom strike while others will.

Phil

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05-26-2015 08:03 PM  3 years agoPost 16
rudyy

rrElite Veteran

E. Amherst, NY

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It sounds like maybe a FBL sensor and the link died in the crash.
I wiggle every single wire on the test bench and nothing happens. The only suspect right now is the vibration that causes the FBL sensor to act abnormally. I am going to rebuild the engine before getting it airborne again.

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05-26-2015 10:06 PM  3 years agoPost 17
Aaron29

rrProfessor

USA

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Sorry poor choice of words I meant to say the FBL caused the crash. And the link died from the crash.

A bad sensor maybe.

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05-27-2015 12:09 AM  3 years agoPost 18
RappyTappy

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Traveling the USA

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I had a ball link come off on my FB Fury back in the day and It stayed in one piece and let me get er down, just felt like something was off and when I tried to go negative the heli had a hard time coming down and control was delayed, FB for the win lol

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