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04-07-2018 09:54 AM  3 months agoPost 1
PaulBowen

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Victoria, Australia.

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I’ve often wondered why we don’t use teetering delta-3 tail rotors like on full size machines, particularly on our larger models.

I believe the early X-Cells used to have teetering tails and also the Logo 800 has a damped tail.

Futaba T18SZ, JR Propo XG14, Hirobo fanatic!

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04-07-2018 10:09 AM  3 months agoPost 2
IYKIST

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London united kingdom

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The Early Robbe Schluter Futura gold did have teetering and dampening in the tail blade hub, i think it did not made a noticeable difference in flight to justify it.

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04-07-2018 10:30 AM  3 months agoPost 3
wjvail

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Meridian, Mississippi

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The earliest X-Cell did have a teetering tail. It was accomplished by mounting the tail rotor hub to the tail rotor output shaft with a piece of fuel tubing between the two. The assembly was located, driven and secured by a small diagonal pin that ran through the hub and tail rotor output shaft.

I never had much problem with the arrangement but it did require maintenance (the tubing could get worn). It was from a time with wire drive tails and mechanical rate gyros. Almost certainly it would not hold up to today's flying.

I can't say it ever helped or hurt. I removed the teetering tail at the same time I changed to a more modern gyro and switched to a torque tube drive. Not surprisingly I noticed a massive improvement in tail performance so it was hard to say what effect the teetering tail had.

Figure #9. http://alshobbysite.com/rchelibase/xcell/1001pl-2.pdf

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04-07-2018 10:44 AM  3 months agoPost 4
PaulBowen

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Victoria, Australia.

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I think it would relieve some of the side loads on the blades and bearings. It would have no effect on tail performance.

Futaba T18SZ, JR Propo XG14, Hirobo fanatic!

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04-08-2018 03:35 PM  3 months agoPost 5
Dr.Ben

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Richmond, VA, USA

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It would appear if you are going to embellish/refine a simple tail rotor head design, Chinese weights give the greatest benefit to to the system. As noted, MA abandoned the delta hubs when issues arose with the 3mm allen bolts holding the grips in place were snapping in flight even with carbon tail blades (NOT due to the delta).

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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HomeAircraftHelicopterMain Discussion › Teetering tail rotors
04-08-2018 04:24 PM  3 months ago •• Post 6 ••
A&J

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Hudson FL 34667

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If you have notice the Goblin does not use a Ridgid tail rotor especially like the smaller 570s..

I could be wrong but I think the 700s are the same way So it can flap.

They used to do this with rotor heads
Number of helis did not have rigid heads

Especially before the flybarless system

Lets do the time warp againnn !

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04-08-2018 07:11 PM  3 months agoPost 7
TMoore

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Cookeville, TN

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A flapping hinge on a model is meaningless. It's needed on a full size to alleviate stress cracking of the shaft behind the hub, not so on a model. Models are overbuilt by several factors and just don't need a hub that flaps. The Magic introduced a flapping hub but it was a POS and I used to go back to the Superior hub and dual BB blade grips routinely on both the Magic and Scout.

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04-08-2018 07:55 PM  3 months agoPost 8
MDSCUSTOMS

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North Wales, U.K.

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The original Graupner / Heim machines also featured this on their tail rotors in much the same way as the XCell 60 mentioned by Wjvail above. Both of mine have it fitted

Mark

I'm only here coz I'm not all there !!

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04-08-2018 08:27 PM  3 months agoPost 9
PaulBowen

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Victoria, Australia.

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Thanks for the comments guys, all very interesting.

I can’t remember this subject ever being discussed before.

Futaba T18SZ, JR Propo XG14, Hirobo fanatic!

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04-08-2018 08:42 PM  3 months agoPost 10
ticedoff8

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Morgan Hill, CA. USA

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PaulBowen
I can’t remember this subject ever being discussed before.
I believe this has been discussed a lot.
But not in the last 20 years or so.
If I recall correctly, this was one of the "important" questions in all of the heli mags back into the 80's 90's.

The closest thing related to this is may be the tailrotor design on the Goblin series helicopters.
They use dampers on the tailrotor feathering shaft instead of the T-shaped hub (like Align).

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