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Old Nov 17, 2012, 10:12 PM
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[QUOTE=tracknoob;23295261]
Was enjoying some circuits, then pitch pumps, then some super fast piros with the plastic Erazor. Well, upon post mortem, it seems that the grub screw on the tail shaft slipped, and it suddenly quit responding to rudder input.[QUOTE]

Sorry to hear about your tail rotor letting go. I had that same thing happen.
I had just lifted off when I heard an odd buzzing noise. Just as I touched down again the tail rotor let go. Yep. The grub screw came loose. It was probably loosened by a minor tail blade ground strike on the previous flight. I put Lock-Tite on, re-tightened it and its been good ever since.

But, I guess seeing the bottom half of the heli spinning around as fast as the upper half leaves an unconscious impression, as I now check that screw before every flying session and every time the tail blades kiss the ground.
Ditto on the chick dance.
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Old Nov 18, 2012, 12:53 AM
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What, I was the second one had ER tail rotor let go on Saturday? I heard a loud noise, landed it, answered a phone, spooled up again forgot to check, and popped.... Since I changed screw which secure the tail rotor holder from M2x5 to M2x8, yesterday was the fouth time this screw shear off. Sigh........
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Old Nov 18, 2012, 07:46 AM
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The Infamous Tail Rotor Screw

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Originally Posted by tracknoob View Post
heh heh


When I picked it up to inspect, the tail rotor was free spinning, but the belt and shaft etc were not moving at all. I think they should have put a flat on that shaft! It's just a undercut radius to help you locate where to align it, but that doesn't help with good seating of the grub. If I wasn't using a known good preassembled tail unit, I'd definitely file a flat on that shaft and use plenty of good old Loctite on the grub screw.
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Originally Posted by GTstrudl View Post
Since I changed screw which secure the tail rotor holder from M2x5 to M2x8, yesterday was the fouth time this screw shear off. Sigh........
This argument about the tail rotor screw not holding securely reminds me of the long running argument on the V200D01 forum about soft, easily striped main gears.
Instead of a flat to seat the screw, the groove in the tail shaft indicates to me that it's a designed in weak spot. The tail rotor can disengage from the tail shaft, but the groove keeps it on the shaft. If that screw was not allowed to lose its grip a torsional overload, like a ground strike, might cause a failure farther up the drive line. So, instead of a screw coming loose you might get a bent tail shaft or a broken belt. Take your pick.
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Old Nov 18, 2012, 11:37 AM
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Three tail blowouts on three separate ER's! Not good. Need a Mod for that!

11:35 now. If I go get my 4.0 packs and charge them, I can have the 600 in the air by 3pm. High of 50 at 3pm. Fly for an hour.. Yeah, I think I will..
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Old Nov 18, 2012, 05:56 PM
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Dusting Off The T-Rex 600EFL

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Three tail blowouts on three separate ER's! Not good. Need a Mod for that!

11:35 now. If I go get my 4.0 packs and charge them, I can have the 600 in the air by 3pm. High of 50 at 3pm. Fly for an hour.. Yeah, I think I will..
It's been two months since I had the 600EFL in the air. I sure am out of practice at handling that big ole' bird, especially after spending so much time on the 450! I kept a lot of expo dialed-in which makes it more difficult when landing. It sure felt good to fly her though!

I'm back home with the 600EFL on the dining room table. This is the first time I've had the 600 back home for several weeks. Boy, it sure seems big! I'm trying to wrap my head around the Trekker's size. It will hang off the ends of the table.

Same ole' HeliGriff highlights, from today. Nothing new.. turn your sound up!

HeliGriff T-Rex 600EFL DFC 11.18.12 (3 min 6 sec)
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Old Nov 18, 2012, 08:55 PM
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Quote:
Originally Posted by dsobbe View Post
This argument about the tail rotor screw not holding securely reminds me of the long running argument on the V200D01 forum about soft, easily striped main gears.
Instead of a flat to seat the screw, the groove in the tail shaft indicates to me that it's a designed in weak spot. The tail rotor can disengage from the tail shaft, but the groove keeps it on the shaft. If that screw was not allowed to lose its grip a torsional overload, like a ground strike, might cause a failure farther up the drive line. So, instead of a screw coming loose you might get a bent tail shaft or a broken belt. Take your pick.
Are you guy still using M2x5 for the screw which secure tail blade holder?
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Old Nov 18, 2012, 09:57 PM
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Quote:
Originally Posted by dsobbe View Post
This argument about the tail rotor screw not holding securely reminds me of the long running argument on the V200D01 forum about soft, easily striped main gears... instead of a screw coming loose you might get a bent tail shaft or a broken belt. Take your pick.
Yup, always something in the chain to be broken when the irresistible force meets the immovable object!

I got a chance to do a quick test hover on it in the driveway and all seems well (except blade tracking off maybe 1/8 inch). Given it's now got a new boom, gears, mainshaft, feathering shaft, swash, flybar, blades, etc, it does not surprise me that it might need a tweak or two, but hopefully this time everything that rotates is properly secured and Loctited.

I also did heed the earlier advice and firmly seated the boom into the plastic housing making sure it was fully engaged with anti rotation pin, and fully seated into the housing as far as it can go, then clamped it into that orientation, later taking up the belt slack using only the tail piece for adjustment.

I was worried about running out of boom, but all seems to be fine, so since I've never noticed the tailpiece slipping, this method is probably the cat's meow for avoiding belt 'de-tensioning' due to hard maneuvers and/or over time, that seems to plague the cheaper 400-450 sized machines.

Will give it a more through test flight at the field tomorrow.
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Old Nov 18, 2012, 10:21 PM
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...I was worried about running out of boom, but all seems to be fine, so since I've never noticed the tailpiece slipping, this method is probably the cat's meow for avoiding belt 'de-tensioning' due to hard maneuvers and/or over time, that seems to plague the cheaper 400-450 sized machines.

Will give it a more through test flight at the field tomorrow.
On my ER450, the boom was securely all the way into the transmission. I would draw back on the tail assembly to tighten the belt. However, this does not leave much of the boom inside the tail housing. The tail assembly would sometimes cock to the right because of this. It seems that the boom should be longer or the belt shorter to me. Hopefully your fix is the solution!
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Old Nov 19, 2012, 11:33 AM
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Quote:
Originally Posted by dsobbe View Post
This argument about the tail rotor screw not holding securely reminds me of the long running argument on the V200D01 forum about soft, easily striped main gears.
Instead of a flat to seat the screw, the groove in the tail shaft indicates to me that it's a designed in weak spot. The tail rotor can disengage from the tail shaft, but the groove keeps it on the shaft. If that screw was not allowed to lose its grip a torsional overload, like a ground strike, might cause a failure farther up the drive line. So, instead of a screw coming loose you might get a bent tail shaft or a broken belt. Take your pick.
When my ER tail rotor disengaged, it's always get tail rotor and tail rotor holder disengaged together.
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Old Nov 19, 2012, 03:44 PM
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Will give it a more through test flight at the field tomorrow.
Put it through the paces this AM and it looks good except I had very little tail movement, i.e. piro rate... looking at the tail slider and fork, it was not moving from 'stop to stop' as I would normally expect to see, since that's the degree of travel I set up for. I was scratching my head for a minute until I realized that the boom I used to replace the damaged one already had a servo mounted on it, so it has a different arm length than the one that was originally installed! Doh! All I had done at replacement time was check 90 degree centering and basic operation, did not look at the limits. The GA250 gyro has a process for setting the left and right servo travel limits, so I just need to do that set-up again in order to 'recover' full servo movement. I can see that the servo is only moving about 30 degrees total. That's good for speed of response, but bad for mechanical advantage if I were to lengthen the servo arm to make that work instead of extending the servo movement limits.
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Old Nov 19, 2012, 06:06 PM
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Originally Posted by tracknoob View Post
Put it through the paces this AM and it looks good except I had very little tail movement, i.e. piro rate... looking at the tail slider and fork, it was not moving from 'stop to stop' as I would normally expect to see, since that's the degree of travel I set up for. I was scratching my head for a minute until I realized that the boom I used to replace the damaged one already had a servo mounted on it, so it has a different arm length than the one that was originally installed! Doh! All I had done at replacement time was check 90 degree centering and basic operation, did not look at the limits. The GA250 gyro has a process for setting the left and right servo travel limits, so I just need to do that set-up again in order to 'recover' full servo movement. I can see that the servo is only moving about 30 degrees total. That's good for speed of response, but bad for mechanical advantage if I were to lengthen the servo arm to make that work instead of extending the servo movement limits.
There's a lot to remember! Reminds me of when I spun up the 450 with the gyro reversed Glad you have under control!
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Old Nov 19, 2012, 06:18 PM
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Funny things happen that you never expect. I wasn't going to post yesterday's video because it is crappy, boring, and nothing new. Besides, I was so out of practice! Today, someone posted a nice comment about it on YouTube. You never know when you are helping other people. What you might think is insignificant may be exactly what someone else is looking for. Ah.. doesn't that just make ya feel all warm inside?

7
Seven
VII
IIII II
3+4

...more days. why do I always have things shipped over a holiday?
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Old Nov 19, 2012, 06:39 PM
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7
Seven
VII
IIII II
3+4

...more days. why do I always have things shipped over a holiday?
Sucks to be you
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Old Nov 19, 2012, 06:50 PM
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Sucks to be you
Oh.. that hurt! I see how this is playing!
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Old Nov 19, 2012, 08:55 PM
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Do try to miss the Christmas holidays. I placed an order a couple of years ago with a Chinese vendor and got caught up in Christmas, New Years, and Chinese New year! The order got returned to sender and I never received it. It took about six months for me to get a partial refund. Not good!
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