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Other › The tail of my L400 is not holding too well :)
01-13-2009 12:11 AM  9 years agoPost 1
ke6d

rrApprentice

San Jose, CA

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Since the day I put it together, something about the tail of my L400 that caught my attention - It is not holding solid as my other 4 helis. At first, I was using a Futaba 9257 servo with the GY401. The tail is holding, but I could tell that it is a little "mushy", as soon as I started to fly backward (or raising the nose into tic-toc) the tail would blow badly. I use a large enough servo arm, and adjusted the gyro travel pot to between 80-100%. The HH gain on the gyro is current set at 80%. I could never get the HH gain to the point that the tail started to wag even at 95%.

Convincing that the 9257 is not strong enough for the L400, I replaced it with a 9254 full size tail servo. Now the tail is behaving much better. I can now flip and tic-toc with out blowing out the tail. The tail blows as soon as I started to fly backward. I noticed that during a hover, the tail of my L400 does not hold solid as my T-Rex 600, T-Rex 450 or the Hurricane 550. The tail has the tendency to drift a tiny bit, then comes back.

I have tried pretty much everything I could do with GY401 (this gyro came from my T-Rex 600 and was working very well before I took it out) and am about to swap it for a JR770-3D gyro but I was afraid that I was not the gyro problem but some other factor such as the way I mounted the gyro on to the open frame (my other heli frames have a solid plate that I can tape the gyro on. The L400 has a split in the middle of the frame so when I tape the gyro on, the middle part of the gyro is exposed)

Can someone look at my L400 pictures and tell me what I missed?

Thanks,

Dan

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01-13-2009 01:11 AM  9 years agoPost 2
Terrabit

rrElite Veteran

Seattle, WA - USA

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It is mounted directly over a bearing. You could be getting some noise. Have you tried relocating it? That would be a simple test. Just remember that if you flip the gyro, you'll have to reverse it.

It's wierd that you can turn the gain up so high. Have you checked the input/output voltage with a multimeter?

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01-13-2009 01:23 AM  9 years agoPost 3
ke6d

rrApprentice

San Jose, CA

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Thanks. Now you mentioned about mounting the gyro directly on top of a bearing, I looked at the picture, and sure enough, the GY401 is in the area of the front tail gear bearing.

I also noticed that the tail seems to hold better on some flights. Sometimes it just blows out right away.

I will look for a different place to mount the gyro, but it is going to be tough to find a flat area on the L400 frame.

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01-13-2009 01:49 AM  9 years agoPost 4
ke6d

rrApprentice

San Jose, CA

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May be if I cut a square metal plate and mounted on the frame where the gyro sits right now, then tape the gyro on top of the metal plate. Grounding this plate with the tail boom, the motor block, and the negative motor wire may help in cutting down the noise going to the gyro and static altogether. What do you think?

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01-13-2009 02:02 AM  9 years agoPost 5
Terrabit

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Seattle, WA - USA

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I honestly don't know. That might work. It didn't seem to effect my L10 with G770. Though an L10 would generate a bit less static due to the lower headspeed. I can't imagine it would hurt to try.

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01-13-2009 02:24 AM  9 years agoPost 6
ke6d

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San Jose, CA

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Thank you Terrabit. The headspeed thing that you just mentioned explained a lot. I went out flying yesterday. The first flight was ok. The tail was not solid but it was holding. I was able to tic-toc, flip, funnel, and inverted flying as I normally do for 5:00 min. I had a "40+ charge" FlightPower pack on. The headspeed was around 2600 rpm.

On the next flight, I put on a new pack (5+ charge), then proceed to take off. The headspeed was noticeably higher. As soon as I pulled into a tic-toc, the tail blows 90 degrees. I quickly recovered then did a sharp turn around intending to land. The L400 almost rolled over on its own after the turn (it was not me. The heli was already flying straight, then decided to roll slowly) I recovered it the second time, then landed it immediately.

Yesterday weather in CA was warm and dry. I now believe that higher headspeed + static was the cause of the tail problem on my L400.

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01-13-2009 03:02 AM  9 years agoPost 7
OICU812

rrMaster

Edson, Alberta, Canada

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As oth4ers mentioned, move it back and if you can get a small plate to isolte then cool to try. The 401 will only of couse go so far. If you do decide to change it down the road, do not go with a 770, rather spend abit more and get a Spartan or Solid G, much much better gyros.

...Once upon a time there were Nitros, flybars and frequency pins...

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01-13-2009 03:42 AM  9 years agoPost 8
Ronald Thomas

rrMaster

Gainesville, Fl, USA

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I actually used a large Futaba servo wheel and it fit perfectly. It helps isolate the gyro and gives you a solid mount.....Ron

Team MikadoUSA 480XXTreme, 550SX, 600SX, 700XXTreme, 800XXTreme!!

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01-14-2009 05:13 AM  9 years agoPost 9
kogibankole

rrKey Veteran

albuquerque/ibadan

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the 401 can hold surprisingly well...what are your transmitter settings? also whats the distance of the ball link from the servos center

if im not blade bogging youll find me pack puffing

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02-02-2009 06:39 PM  9 years agoPost 10
ke6d

rrApprentice

San Jose, CA

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I just want to post an update to the tail problem on the L400 that I have. I grounded the boom, relocated the gyro, change the 401 to Jr7703D. My L400 flies well on all the packs (30+ charge) except one brand new one, I could tell the headspeed went way up on the brand new pack 2700+ rpm. With the higher headspeed, comes the tail holding problem. The tail would respond correctly on a left turn, but hesitate on a right turn. The tail would swing right on a punch out (this only happens on the new pack that I have)

Since I did everything I could as far as the electronic placement is concerned, I was pretty much convinced that it has to be mechanical. I tore the tail section out and check for problem. I was able to track down to a notchy bearing on the tail grips. Replaced the bearing with a good one and sure enough I got tail wag at higher gyro gain (I could never get the tail on my L400 to wag even at 90% gain) It flies nice now after reducing the gyro gain to a gain that I normally use on my other helis (72% on DX7)

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02-02-2009 09:06 PM  9 years agoPost 11
Terrabit

rrElite Veteran

Seattle, WA - USA

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Are you using a voltage drop-down on your tail servo?

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02-02-2009 09:34 PM  9 years agoPost 12
ke6d

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San Jose, CA

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Yes, I have a 5.1 stepdown installed between the gyro and the 9254.

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02-03-2009 01:31 AM  9 years agoPost 13
gravydrive

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Jacksonville, FL

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Do you have your tail thrust bearings installed correctly? There is a typo in the manual.

http://www.runryder.com/t479071p1/?...rust+tail+grips

Murphy's Law Denier

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02-03-2009 01:39 AM  9 years agoPost 14
ke6d

rrApprentice

San Jose, CA

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I don't have a thrusted tail grips on my Logo 400. I was kinda wondering if the non-thrusted tail grips would be locking up at 2700-2800 rpm headspeed.

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02-03-2009 02:13 AM  9 years agoPost 15
OICU812

rrMaster

Edson, Alberta, Canada

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that is likely your problem, I truly suggest getting the thrusted tail.

...Once upon a time there were Nitros, flybars and frequency pins...

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02-04-2009 03:43 AM  9 years agoPost 16
aj0929

rrNovice

Taipei-Taiwan

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I'm a Logo 400 user from Taiwan...
And I have the same problem when I first get the kit!
My setup is: Scorpion HK3026-1600 with 17T
First I use a DS760 with 9256 for my tail.
It can lock well at Normal and Idel(headspeed is about 2500)
For a few great flight, I change to 18T and problem came out!!
When I switch to Idel(headspeed over 2800) the tail blowed!!
Then I change tail server to DS8900G, problem still the same!!
I changed everything include receiver...It still blowed!!

Finally I found...the original tail can't hold on a high headspeed!!
And the problem was went away when I change it to a thrusted tail...
Now my tail is solid as a rock over a headspeed 2800!!

Just share to everyone and sorry for my poor English...

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02-20-2009 12:11 AM  9 years agoPost 17
ke6d

rrApprentice

San Jose, CA

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I finally figured out the cause of my headache It was not the notchy bearing on the tailgrip, 401 gyro, 9650 or 9254 servo, but the "non thrusted" tail grip of the cheap "fly bar" L400.

This explains why my old batteries run fine with it, but the brand new ones cause the tail to "mis-behave" I was running a Scorpion 3026-1600 with a 16T pinion with a target headspeed of 2800 rpm. The Align 75A ESC does not have good governor mode so I rely on TC to set the headspeed that I want to fly. Trouble is when I put in a brand new pack, the tail of the L400 is just locking up and does weird things.

I finally put a CC ESC and set the governor mode at 2500, 2600, and 2800 rpm to test thing out. The L400 flies beautifully at 2500 but at 2600, the problem started to show. At 2800, it is unflyable.

I am certain now that I need a thrusted tail grip for sure. Right now, at 2500 rpm, I am having so much fun with it for the last 6 flights I must say that it is a whole lot more fun than my 6S T600 or Hurricane 550.

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02-20-2009 01:41 AM  9 years agoPost 18
Terrabit

rrElite Veteran

Seattle, WA - USA

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Go Quick UK or Kasama.

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02-20-2009 02:11 AM  9 years agoPost 19
pjpg

rrNovice

Georgia

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when you test out the thrusted tail I wouldnt use the cc esc in governor mode. Some setups or different rpms can cause tail problems with cc gov mode. After it appears it is working then try gov mode.

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02-20-2009 02:32 AM  9 years agoPost 20
jhhyah

rrApprentice

Taipei, Taiwan

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am certain now that I need a thrusted tail grip for sure
yes, it respond much faster. you need it at high headspeed.

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