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Old Jul 21, 2012, 07:42 PM
Safety : practice & promote!
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I took the Trex outdoors today and flew two batteries. I also flew 4 batteries in each of my V911s and 9958s. Frankly, I'm pretty disappointed with the TRex. I was being blown all over the place in wind that the V911s and 9958s could handle quite well. What to do? Well, here's my list of things to consider:

- The headspeed just seems low on this guy. I programmed in a pretty aggressive throttle curve so that I could get the head speed up pretty darned fast. I think replacing the 100X main motor, which has a 9 tooth pinion, with a MSR/9958 motor with an 8 tooth pinion, or, probably better, a V911 or Bravo SX motor with a 7 tooth pinion will help. I'll have to try them on the main gear and see if I can get a good mesh with either one of those.

- The cyclic just doesn't have a lot of authority. I'm bummed that even with my Xtreme swashplate that in theory *SHOULD* have maxed out how much I could tilt my blades, I still had a lot of troubles pushing upwind. I kept ballooning and even had a crash where I was pushed to the side and hit the pavement in a little roll. HIt the throttle hold first though so I don't think there was any damage. Not sure what to do about this.

- The blades are pretty wide and are swept up at the end. I'm thinking that this may have something to do with the low headspeed. Big fat lifting surfaces that work like sails when the the wind blows into them. Perhaps trimming down the blades or finding some other blades to put on might be appropriate. That would increase the headspeed as well. The guys in the MSR/MSRX threads have talked about doing that to help handle wind.

Hmmm...some good options to think about.
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Old Jul 21, 2012, 09:02 PM
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From what I understand, a lower tooth pinion will lower the max head speed. Lowering the main gear teeth count will increase the head speed.
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Old Jul 21, 2012, 09:24 PM
Safety : practice & promote!
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Quote:
Originally Posted by Daryoon View Post
From what I understand, a lower tooth pinion will lower the max head speed. Lowering the main gear teeth count will increase the head speed.
Hmm...okay, I guess I had it backwards. Well, food for thought.


I just flew both of my batteries tonight but I only got 2 minutes of flight out of them both before the heli couldn't maintain altitude! What the heck?

I've heard that main or tail motors going bad might potentially be a cause for batteries to give out prematurely. I can't imagine that it's terribly likely that both of my "new(?)" batteries are crapping out right now at the same time. I'll fly again and see what might be going on.
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Old Jul 21, 2012, 09:38 PM
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Well, crap. This time, I took a freshly charged battery and had the heli hover right in front of my face rather than flying it all over the place. I put back a "linear" throttle curve. However, my flight time was about 3 minutes before the heli couldn't maintain altitude.

The main motor was pretty warm...maybe my main motor is starting to crap out already?
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Old Jul 21, 2012, 09:53 PM
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Just flew the other battery. This time, I only got about 1:45 before it dropped down to ground effect. Both the main motor and tail rotor were pretty hot to the touch. Not so painful that I couldn't keep my fingers on them, but it was definitely up there....

Hmm... could be bad motors? I flew two 4 minute flights earlier today but I was flying them outdoors in the wind so that might have helped cool things down?
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Old Jul 22, 2012, 12:29 AM
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Okay! Some success!

Remember that experiment earlier where I tried soldering an eflite plug to my skids so that I could use both kinds of batteries? Well, it occurred to me tonight that maybe--just maybe--I had introduced a bad solder joint there or something.

So, since I have another spare set of skids on the way to me, I went ahead and completely desoldered the power wires from the skids and spliced an eflite plug directly onto them. Now my skids aren't connected to anything so I can't use the Align batteries but now I can plug in one of my Turnigy NanoTechs.

I flew 2 full 4:30 minute flights with a 7-minute cool-down period between them! No problems. The heli seemed to have more punch on takeoff, too. Until something else "breaks", I'm going to call this one solved.

Now I just have to find a nice way to secure my Nano-Techs onto my TRex skids. I'm using a wire right now. Unlike the V911, the canopy is too fat for me to just shove the battery into it. What I probably need to do is fabricate a small lightweight cage or something out of plastic. I wonder if the skids from another heli that can comfortably hold an eflite battery would fit on the Align.
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Old Jul 23, 2012, 12:12 PM
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Tbe

Hello everyone, first post on these forums.
I've been flying fixed pitch single rotor for a few months now, and I've gotten fairly comfortable with flying and repairing my helis. I recently picked up a Trex 100x, bound it to my 9x and started flying it around.
At first, I had some serious problems, major TBE and on increasing throttle, it would yaw slowly for about 15 degrees, then swing quickly to 180 degrees and cut hard left. I adjusted the gyro gain and it's now holding direction much better (still some fine adjustment to go), however the TBE just won't go away.
So far I have: loosened all flybar links to the point of unrestricted movement; lubed the feathering shaft and checked for obstructions; loosened jesus bolt to make sure no deformation. There is no restriction at all in the blades/flybar. I can breathe on the paddle and change the pitch of the blades. All this has reduced the TBE to the point where it's fairly manageable, but it still hovers in a 3-4 foot area instead of holding position.
I have not disassembled the swash, as it looks fine (no separation or binding). Servo arms and all linkages are not binding. One thing I have noticed is that the main drive gear is warped. Could this cause the TBE?
Any ideas or suggestions would be greatly appreciated. Thank you.
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Old Jul 23, 2012, 04:23 PM
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hi larrydust, welcome to RCG! Nice to hear from another TRex 100X owner.

TBE is a tough one to solve. Since you've done so much with your existing parts, I'd hate to say it but you *might* need to start swapping out parts with new ones to see if that helps. I've had to debug TBE on some of my coaxials when I first got into the hobby and it pretty much revolved around swapping out flybars and linkages until it went away. I know that's probably not what you wanted to hear ($$$) especially if it doesn't immediately solve your problem.

Have you crashed your heli? Is it possible that your mainshaft might have a little warp in it?

I know that this little heli can be made to work well because I have one that does.... good luck with it and let us know how things are going. Some RCG folks take close-up shots of linkages and rotor head and post them for others to see and comment on. Might help?
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Old Jul 23, 2012, 05:56 PM
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Thank you for the welcome and response!

I have had a few crashes, but I just checked the main shaft and it appears to be straight. Damage so far has been a bent tail boom (which I straightened out) and a cracked canopy. There is no other damage that I can see. I've uploaded a couple pics in case there is something I've missed.

Is it possible that the flybar is too loose now? I had lightly sanded down part of the rotor housing to allow for better movement. I didn't think it would be a problem, but now I'm wondering.

I'm just now noticing that when I spin the gear by hand that the swash is "jiggling" a little. Looking at it from behind, the servo links are and swash guide pin are moving left/right as the shaft spins. I'll probably try to take apart the swash later tonight and see if that helps.
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Old Jul 23, 2012, 06:58 PM
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Hmmm... it seems like it would make sense not to make the screws too loose. Shouldn't they be tight enough not to be wobbly but loose enough that they move freely?

Is your flybar straight? Do the paddles move in the same plane? Is your flybar balanced (e.g. paddles the same weight)? I'm not entirely sure how to test the last part but I do know some guys that do when they make custom paddles for their V911 helis. Let me know if you want to try that and I'll get you in touch with some guys who know more about that then me.

(EDIT: you can check this thread out for instance... http://www.rcgroups.com/forums/showthread.php?t=1611495 it's all about the S107G but some of the principles are the same)

(EDIT 2: here's some more good info... http://www.rchelicopterfun.com/toilet-bowl-effect.html)

FWIW, Amazon.com sells most of the Trex 100X parts, as far as I can tell. Nice if your LHS doesn't stock them.
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Last edited by RoboHeli; Jul 23, 2012 at 07:01 PM. Reason: added URLs
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Old Jul 23, 2012, 07:02 PM
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(note, I just added a couple of URLs to the previous post)
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Old Jul 24, 2012, 11:47 PM
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TBE gone!

TBE is gone. I spent a few hours going over the swash and finally got rid of the TBE.

On close inspection, I found minor binding between the upper swash and the ball pivot. After removing the ball pivot, I found an imperfection on the inside of the upper swash. This small piece of plastic was keeping the ball pivot from moving freely. I've attached a photo of the upper swash. It's tough to see, but it's inside the ring, on the lower part.

I sanded down the inside of the upper swash until there was unrestricted movement of the pivot ball. In fact... I may have taken off too much. I can pop the ball pivot out by tapping it, instead of having to dig it out.

However, after putting it all back together... the dreaded "Toilet Bowl Effect" is gone! I am able to hold a steady hover for a while now, and was even able to do a few laps in my small room. It slides a little, but I can adjust my flying style to it or mix it out on TX and it's not really an issue.

Now to put in some flying time with this bird!
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Old Jul 25, 2012, 03:42 AM
Did you check the FAQ already?
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Congrats on fixing theTBE. Perhaps more people with this heli have the same cause for their 100s/100x TBE.
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Old Jul 28, 2012, 08:44 PM
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Battery recommendation

I have about twenty flights done on each of the original 150mAh batteries that came with my TRex 100x, and they don't seem to be very good. The longest flight I've had (out of approx. 40) is 3m45s. My average flight times are closer to 2m30s. I only use the stock CH-100 charger. (My other helis average 7-8min on their 150mAh batteries.)

The main and tail motors are not hot at all. After a 2 1/2 min flight, they are barely warm to the touch. I have decided to try a new set of batteries and hope for the best. Does anyone have any batteries that they have had good results with? Preferably ones which fit the stock skids, and can use the stock charger.

I saw these at HK. Any opinions?
http://www.hobbyking.com/hobbyking/s...Trex_100_.html
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Old Jul 28, 2012, 08:55 PM
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Hi larrydust!

I fly the Turnigy Nano-tech 160s with the Eflite plug. I modded my TRex so that I could use those batteries instead of the stock ones. That way, all of my helicopters use the same battery.

If the TRex nano-techs are exactly the same battery as the ones I'm using:

http://www.hobbyking.com/hobbyking/s...dProduct=11893

then you should bet able to get 4 minutes+ fairly easily. I only ever fly to 4 minutes as a general rule so I can't speak for how much you can push it after that. Mind you, I've seen that the heli doesn't have a lot of lift compared to others (maybe slow headspeed?) and so the lack of lift is the first thing you start to see.

Still though, can't beat the price, right?
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