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T-REX 500 › Still wag have tried alot any suggestions
01-17-2009 09:11 PM  9 years agoPost 1
kaz172

rrApprentice

auburn, WA -usa.

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I built a trex 500 esp and had tail wag and did not have a locked in feel. I have a spartan gyro with 9257 servo. So I did the tail mod to take the looseness out of the tail grips and rechecked everything I think. So then I upgraded the second bearing on the tt, the new plexy glass reciever shelf thing for the gyro, zeal taped the gyro. The tail slider is nice and loose I think. I have not done the mod for the pushrod using a carbon fiber rod and putting the pushrod inside of it and not using the pushrod guides. I did move my esc up under the battery mount, and changed my throttle curve for normal mode to 0,40,80,90,100. I did read about finless's problem with his esc, I don't know if that just had to do with the solid g gyro or what, but I did not understand about how to check. I can adjust the gain from being a fast little wag to a big slow wag. When I hover it wags and when I give it throttle while in a hover the tail blows out about 4-5 inches and then corects then starts a wag. I have had this heli built for atleast 1 month now and have yet to take it to the field for fun. I used to have a 450 V2 so I am decent at setup. Any ideas, I am really not having fun with this thing. There is no damage to the heli it is brand new except for when I was playing with the heli in the garage and tilted it to the right and nicked the tail blades just a little. Please help do you think my 9257 is going out, how could you tell. Thanks Kyle

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01-17-2009 10:10 PM  9 years agoPost 2
Jamin_00

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Essex UK

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Have you checked the main bearings.My mate had a wag and checked everything it was a brand new set that were bad and were grinding which caused the wag.

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01-18-2009 01:23 AM  9 years agoPost 3
kaz172

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auburn, WA -usa.

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I checked by spinning them while in the heli but did not feel notchy. I did not take them out though.

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01-20-2009 04:11 AM  9 years agoPost 4
erict

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Ct

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sounds like something is loose in the drive train. one way shot? tail belt slipping or too tight? the esp has a tt.. never mind. maybe one of those gears is slipping. what headspeed? just a couple of things off the top of my head ...

good luck

eric

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01-20-2009 04:21 AM  9 years agoPost 5
dave75d

rrKey Veteran

Jacksonville, FL

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post batt and pinion. whats headspeed? i run 2650 in idle 2

ten grand in helis and all i can do is hover

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01-20-2009 06:02 PM  9 years agoPost 6
gtech

rrNovice

Riverside, CA

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if you are running the esc in govenor mode take it out and just use a straight throttle curve. I fought with the same problem for quit a while. I found that when in gov mode it causes the tail to wag. I think is from the constant adjusting of the motor speed. Mine is rock solid now. Mike.

SHUT UP AND FLY!!!!

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01-20-2009 08:33 PM  9 years agoPost 7
hovercraft

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USA

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I'm not sure what zeal tape is, but did you use the metal plate that came with your DS760?

Did you adjust the tail in rate mode so that, in a hover, with TX rudder trim at zero, the heli doesn't rotate left or right.

This is done by a mechanical adjustment on the rudder ball links, not electronically, as specified in the manual.

It took me a few short flights until I got it just right. A turn or 2, oops just a little more, dang...need one more turn.

At this point, bump your gyro gain up so that it is in HH mode.
My HH gain is 75% on my X9303. I am using a 3517MG for rudder and a Scorpion 3026-1400 w/15T revco pinion.

Also, make sure your left and right endpoints of your pitch slider doesn't bind(during DS760 programming).

The manual explains the above and that you must have your rudder trim on your TX centered and that yaw must be mechanically set in rate mode.

The above technique worked for me.

If you are hovering, then governor mode shouldn't have an effect(it didn't in my case). If you are experiencing headspeed fluctuations then there is a problem with that, whatever the cause(maybe it is the gov, worth a shot, just saying it didn't effect me).

Another thought....If you are using the Align metal tail grips, then you should use counterbalance(i.e. the HEIM JOINT mod). The force required to move the metal tail grip pitch away from zero pitch was measured by Robin, aka HEIM JOINT, at 40 ounces in his lab. I think he mentioned that the stock plastic grip required 15 ounces or so(in his video demonstration of the "tennis racket" effect and his measurements of the forces involved.

My point being that the 9257 has about 28 oz-in of torque. If your rudder servo arm radius is 10mm(to give the pushrod a straight shot to the pitch slider bellcrank thru the rod guides) then the max force that the 9257 can apply is 28oz-in x 25.4mm/in divided by 10mm = 71 ounces. If one has 2 or 3 oz. of drag in the linkage(pushrod drag, pitch slider drag, etc.), then about 42 ounces of force is required to move the tail pitch from zero pitch at hovering speed.
60% of the servo's force is being used just in moving the tail pitch from 0. That's a lot.

You can feel the effect by hand if you remove your main rotors, disconnect the ball link from the rudder servo, and spool up the head(as much as you dare with the heli anchored) and try to move the pushrod. If you then add some washers(cheap counterweight) to the bolts that hold the tail blade grips and repeat, you can really feel the difference.

HEIM machines calibrated weights(calibrated using test measurement instrumentation) for a wide variety of tail grips.

For me, by his video demo, it was definitely an eye opener(given the magnitude of forces measured).

FWIW

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01-20-2009 08:53 PM  9 years agoPost 8
pjh

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Hampshire England

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I think you will always have problems is your throttle is set up as you say...quote" and changed my throttle curve for normal mode to 0,40,80,90,100."unquote
That should read in normal mode for instance....0,80,80,80,80 in otherwords a straight throttle curve after the first point on the tx curve and idleups for instance 85,85,85,85,85 and so on. hope that helps

The older i get the faster i was

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01-20-2009 10:04 PM  9 years agoPost 9
avconslt

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Houston, Texas

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Kyle,

You need to replace the Zeal tape with the original foam tape that comes with the gyro! My Trex 500 is set up pretty much just like yours and I had the same problem, until someone told me to replace the Zeal tape with the original foam tape and the tail wag went away! Apparently the Zeal was meant for nitro helis to take out the vibrations and has too much play in it for the Trex 500 gyros! Give it a try I think you will be surprised!

Richard

o

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01-21-2009 04:03 PM  9 years agoPost 10
kaz172

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auburn, WA -usa.

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Hi thanks for all the idea's. I don't know the headspeed but I am running stock motor and esc with the 13t pinion on a protek 6s1p 2200mah. I just put the small wheel horn on and on the outside not middle hole and adjusted the normal throttle curve to 0,80,80,80,80. I just hovered about 2 feet off the ground in the garage and all was good, no wag atleast in a hover, big improvement. Does that sound ok with the normal throttle curve or am I just masking somithing up. My 450 used to be in normal mode with an adjusted throttle curve and the tail never wagged with a 401. Does anyone have a different normal throttle curve with no wag? I am using the metal plate for the gyro, I used the regular tape that came with it but it wagged with that so I bought the zeal tape after alot of good reviews. I guess I forgot to say that I did the Heim mod on the tail, and also the heim weights. When I get a chance I will fly alittle outside and post back thank you all.

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01-21-2009 08:59 PM  9 years agoPost 11
pjh

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Hampshire England

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I think you need to do some reading my friend. The suggested throttle figures were only that"suggested" The important point is that the throttle always stays constant except for that first startup. that is why the idleup curves are a straight line eg:95,95,95,95,95 or 37,37,37,37,37(or any other set of numbers).in fact that figure depends upon the headspeed you want and the throttle% in your tx that gives that speed. I know I haven't explained this very well but in order for your gyro to be able to keep up with the heli you must have constant revs. I would leave the tail alone and get that esc set up properly.good luck it sounds like you are nearly there.

The older i get the faster i was

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01-21-2009 09:32 PM  9 years agoPost 12
pjh

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Hampshire England

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this might help
http://video.helifreak.com/?subpath...e=esc_setup.wmv

The older i get the faster i was

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01-22-2009 03:00 AM  9 years agoPost 13
dva

rrNovice

Maricopa, AZ

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500ESP
500L motor w/ 13T
6s 2350 25c zippy packs
Spartan Gyro
Futaba 9457 servo
I have 0 87 95 on my 9303 for normal mode and have no tail wag. Had no tail wag with a 401 also.

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01-22-2009 09:05 AM  9 years agoPost 14
pjh

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Hampshire England

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dva,
I understand you have no wag because you are flying at over half stick(unless inverted) ie:a v curve on fixed end points but......your heli headspeed between 0 and 87 will be constantly changing but your pitch curve won't let the heli take off will it. In gov mode your throttle curve should be flat after the first stick position.

The older i get the faster i was

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01-22-2009 10:13 PM  9 years agoPost 15
kaz172

rrApprentice

auburn, WA -usa.

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Thanks all. I went to the field today to fly for the first time because for some reason the tail did not wag as much just a little in normal mode 0,80,80,80,80 in Idle up at 95.95.95.95 it held except for backwards wagged just a little and felt diferent in forward flight the heli just felt a little wierd. I had my esc already setup by finless at 1,2,1,2,3 does that sound ok? I think I just need to mess with my gain as the tail feels slow and unresponsive at certain spots on the stick maybe i need to adjust something I have 20% expo and 100 dr on the rudder channel and my gain was at 37 i think for the gear channel with my dx7. I do have the Heim mod weights on the tail so I am probably needing to bring the gain down some. Thanks for the help with the normal throttle curve like I said the tail still wags in flight but it is alot better, plus I just put it in idle up as soon as I take off. I still have the zeal tape holding the gyro on with a velcro wrap around it do you think that is my only problem now or is something else. I will have to buy somemore 3m tape if you think that is the best. Thanks

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01-23-2009 12:03 AM  9 years agoPost 16
dva

rrNovice

Maricopa, AZ

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dva,
I understand you have no wag because you are flying at over half stick(unless inverted) ie:a v curve on fixed end points but......your heli headspeed between 0 and 87 will be constantly changing but your pitch curve won't let the heli take off will it. In gov mode your throttle curve should be flat after the first stick position.
I am running the 0 87 95 in normal, 95 87 95 in idle 1 and 100 94 100 in ilde 2. As for the pitch I will not take off until over center stick in normal mode because center stick is 0º pitch. I do not run governer mode becasue I have had problems in the past with govener mode.

With a throttle curve it helps keep the head speed more constant when a load is applied.

DVA

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01-24-2009 12:41 AM  9 years agoPost 17
kaz172

rrApprentice

auburn, WA -usa.

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Just took tail apart to make sure the thrust bearing was lubed (have done it once but thought I would really cake it on this time) and noticed that the regular bearing on the inside of the blade holder when turned it felt a little notchy, not like it was really stuck or anything but just felt some notches in it while turning. WOHOO, do you think this is the culprit to my tail wag and trouble with my tail. Does notches in the tail make the heli wag? Can I replace with off brand bearing 5x9x3 or should I stick to the align Item# 5x9x3. Thanks kyle

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01-24-2009 04:28 AM  9 years agoPost 18
dva

rrNovice

Maricopa, AZ

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you can pick up bearings at helidirect.com

http://www.helidirect.com/product_i...roducts_id=1200

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