babyhuey

Hi bladeboy,
Yeah I have a 37 and I like it even though I haven't flown it much. I bought it off ebay used and it has problems so I started modifing it with a longer Trex tail and a 60 alloy head.
It looks cool but I haven't flown it yet as we have had windy rainy weather for over a week.
I will try to post Pics on here later.

Thanks for the help everyone,
Huey

mozzzy_2000

How should the #36 fly in totally stock form? Mine is pretty lousy. I have to turn the gyro sensitivity almost all the way down to stop the tail wagging and the you have to virtually go 75% throttle before it lifts off its skids and then its just barely holds a hover with almost zero climb at full throttle.
I know these are known for the lousy electronics and I do have a brushless setup to swap over but in stock form I am rather godsmacked at gutless the stock motor is.
Any thoughts?

Rattlecat

With a stock radio you will have some trouble fine tuning it. The 36 will fly very well when mechanically optimized and fine tuned with a programmable radio. These things aren't like an on-off switch. They are a fine responding analog machine. Sounds like you could adjust the off set knob PLT or PIT, I forgot which is which. It is the one that swings the blade range up or down not the one that increases or decreases the range.

CH

Rattlecat

I did 5 test flights this morning and found I had not noticed how sloppy my altitude control had gotten. Now my turns are more professional. Nothing loosened up, but I do need to adjust my mid stick down to get better altitude control for landing. I guess I have the throttle too high mid down. I now remember tweeking it up a month ago when the air was thin and the heli was mushy. Now that it has cooled to the 50 - 60*F range, I need less headspeed.
I wish I had done the anti rotation mod long ago.
CH

HeliSmith

I went belt and it is great but my next project DF4 will be BL main and dual brushed tail. I am almost done with the son's heli and I will make a video.

drobin

CH, what do you think of using molylube on the head.I have some left over from my vcr and tape deck repair days.
dave

Rattlecat

Just replace the aluminum ball links with Align stainless steel balls and links, and do not use any lube. It only makes the wear particles stick and make an abrasive paste. The only one that may not fit is the one on the bottom of the mixer arm to blade grip link. There is a close swing between the ball and flybar bushing arm.
Some silicone grease on the area where the washout base slides on the main shaft is good. But don't use anything except maybe graphite on the aluminum, and even that is a waste of time.

CH

Mcflyman

For sale 1 #36 like new 6 new pairs of main blades. No electronic included
PM me with an offer

mozzzy_2000

No electronics! Wow that actually makes it a decent heli! lol man o' man are the electronics trash in these things trash or what!

mozzzy_2000

What radio systems have you guys upgraded too? I'm particularly interested in the spektrum Dx7 at this stage. Looks like a pretty nice bit of kit. The fact that I eventually want to get into something bigger makes think I should get a quality radio that can grow with me. Thoughts?

drobin

The DX7 is an excellent radio.And you can use it on almost anything you want to fly.

bladeboy

Hi guy's
I noticed the tracking is out on mmine i span the heli up with it in my hand there is plenty of lift,,

But it realy want,s to twist in my hand,s poor little rotor has'nt a chance of stopping it..

I did read some info in the thread a little way's back,,,but i had trouble eyeballing which blade was out either red or blue..

.......thank,s guy's[sm=75_75.gif]

brettw

Hi Guys,

Does anyone have a Walkera cnc tail? If so can you post a few pictures of it mainly from the back at full right stick and with the sticks centered setup for a stable hover.

From reading this forum there does not seem to be anything that I have done incorrectly. http://www.walkera-heli.com/forum/viewtopic.php?t=15

I have two issues.

1. The ball links that move the hub on the shaft hit the L arm link at full right stick.

2. To keep the heli from spinning the tail hub needs to be almost all the way over towards the boom, which may not be a problem apart from my first issue.

The only thing that I have found is that the boom that comes with the cnc tail is longer, would this make that much of a difference and is it worth cutting it back to the stock size?

Any help would be great.

Cheers

Brett

Rattlecat

Well, I finally bit the bullit and did the Rollin Thunder frame mod for easy main gear removal. I feared it would make the frame weak and MORE flexy, but I couldn't see any difference. Now I can pop the main right off.
I think the tail drive's one-way sleeve could be changed to be easily removed and if you could drop the owb sleeve out, both gears come right out without a frame mod.
Now after fixing the anti rotation problem, my owb is sticking again. I will look at the two set screws on the owb sleeve and see if they are cocking the owb. I forgot to put my shim mod under the owb sleeve. With those you keep the owb sleeve tracked better.

UK people : I call the little screws SET SCREWS not grub screws. Grub screws remind me of those nasty little lawn eating GRUB WORMS that I had a problem with. So, THAT is the reason I don't call them ^%$&^%*^(*& GRUB SCREWS.

CH

babyhuey

HI Bladeboy,
First holding the Heli in your hand and running it is VERY DANGEROUS!
Second, Your tracking won't make your tail twist. the operation of the gyro is reversed or too weak, the head speed is to low or a combination of the two.
You need to put on training gear and on a smooth surface see if the Heli spins on the ground. If it does reverse the gyro with the switch on it's side and try that. Then if it is stable but spins when you use the rudder reverse channel four on the TX.
Also make sure that the gyro sensitivity isn't too low or the gyro simply won't be operating.

I think that's all,

Huey

babyhuey

Hello Brett,
I have that tail on a 37 and haven't noticed any problems with it hitting or binding. The longer boom should make the tail rotor more effective so I doubt that is the problem.
I am going to look at my Heli and make sure that mine doesn't have that problem and I will get back to you.

Huey

brettw

Thanks babyhuey..

Brett

Rattlecat

Better rethink tracking, pitch/headspeed balance, poor efficiency blades, and slop in the head parts. They all contribute to rotor drag, and a badly out of track rotor can develope an equivalent blade frontal surface area of 3+ x. That can mean a LOT of drag.
My slider has it's neutral nearly in the center of the tail shaft, because I optimized the rotor. I can switch from normal to HH and not see much if any trim change in hover.
I would need to check the tail mechanism, but if it's configured like the rest, then it indicates a rotor drag problem or possible slipping tail drive component. Usually when slipping they go totally bad FAST. Also operating it like that could cause a servo failure if your gyro does not have a limit function.
You may find a really loose turn table and securely fasten the heli to it, then observe the tracking and slider position. But since I don't know your mechanical aptitude, need to warn that it could break loose on you, so be extra sure it is locked down good.

CH

Orion1024

Brett,

Do you mean the slider needs to be almost all the way to the left? I do have a CNC tail unit, but not the Walkera one (it's the Sonix CNC). I tried it on the MX400 and it didn't work...looks like the tail gear pitch is wrong for the MX. Anyway, for the low tail speed on the 36, I don't think the alu tail unit is really necessary or that beneficial. Do keep in mind that you might be able to move the tail rotor hub over to the right - this will give you more range for right rudder (when the slider moves to the left). I have my tail hubs as far right as they will go. Some other things to keep in mind... If your motor or battery is underpowered, the heli won't hold well because there isn't enough power to drive both the main rotor and tail rotor when you give it a lot of collective (will yaw left). There can also be a sizable power loss if you aren't using deans and adequate gauge wires. As Chophop mentioned, poor blade tracking will also increase drag and cause vibrations that will interfere with the gyros ability to hold. On my 36 with the stock gyro, I need to set the gain to about 60% to get it to hold reasonbly well. I still use the stock gyro in rate mode, so I also have revo mixing set up on my 6EXH...by using revo mixing you can decrease the gyro gain some (down to about 50% for my setup). For setting up the gyro, make sure the servo horn is close to 90 degrees to the boom and mechanically adjust the slider position so the heli doesn't turn when hovering with the trim at neutral on the TX. Then you can increase the gain to get it to hold better, but the yaw rate will decrease...so it's a compromise between speed and holding ability with the stock gyro.

Rattlecat

See if you can find the dayglow stickers to use as tracking tape. They make a world of difference. I use the pink and green because they are so contrasted, really shows. I roasted 3 batteries, overheated the motor/esc because I didn't set the tracking at all speeds, when I got up to flying speed, it was far out.
CH

Orion,
I think the blades may have been out of balance when you tried the DF36 tail on the MX400. They make a similar sort of buzzing sound. As a mater of fact, they were doing the same on a 36 lately, I put a strip of scotch tape on one tail blade, it got worse, so I removed it, and put one on the other tail blade and my 36 suddenly was so smooth I was amazed. I thought the vibes were from the main rotor. Same thing on the MX a few weeks ago.
Both belts on the 36 and MX400 are the same , a B371T MXL. The MX one is cut a bit more narrow. I think the vibes may come from no undercutting on the Walkera cog pulley. When the bottom of the belt teeth compress around the the cog, they need relief in the cog's tooth profile, meaning a sort of inward cut near the bottom of the pully's teeth. We are paying 1/3 the cost of industrial grade power transmission components. Also, the 36's shaft is probably not true which will show up on the MX due to the 5:1 tail reduction and higher speed.

I went and checked, the MX pulley does not have relief, but they must have compensated by making the teeth more narrow on the pulley so the belt can bunch up. My Walkera pullies are on the helis so I can't check it for now. I did check an Align pulley and it has square teeth, not trapezoidal. And as I remember, they run a square tooth belt. They probably don't want to put up with the teeth chipping on the dovetail cutters. Believe it or not, those filled resins wear the molds out pretty quick, and they are going to have to keep cutting new mold inserts.
Maybe later I'll show a photo of some precision grade pulley teeth so you can see what I mean.

EDIT : You know, as a matter of fact, it seems I remember the Walkera pulley actually having the opposite of a relief cut, a sort of outward curve near the bottom. More like an HTD type timing pulley.

CH

Orion1024

Yeah, I did try the 36 tail unit on the MX and it does work, but I was having a problem with the slider cutting a groove into the shaft and then sticking. The MX tail spins roughly twice as fast, so I would think the tail shaft needs to be very straight or it won't last long. The 36 tail shaft is just too soft...I don't think it will hold up for too long. I was having the problem with the Sonix CNC tail on the MX - the tail pulley has teeth that are shallow and are flat on top...it was chewing up the belt. I put the original tail unit back on and the belt wear stopped, but it still buzzes intermittently and starts to yaw. I haven't touched it for months, but want to get back to it soon and try to figure out what's wrong. It's possible the shaft is slightly bent or somethings out of balance. That's one downside to the high tail speed - everything is a lot more critical. Are you sure the belts are the same? I compared the pitch over the length of the belts and after about 1/2 the length the teeth don't line up anymore. They seem to be ever so slightly different. Damn shame I never did get it working right cause I got everything else setup so nice! Oh well, maybe next year.

brettw

Hi Guys,

Thanks for the replies. Ok here goes..

Its 9pm at night over here so cant test the heli.. However can answer some of the questions
and show you a pic of where the tail needs to sit for a stable hover. Its bad....

It all started when I touched the tail on the ground bent a few parts, yes I know I
was warned against it however got the Walkera cnc tail and head (head not on yet).

Anyway nothing else has changed apart from the new tail so im guessing its was starting to slip before or
there is something fundamentally wrong the way I have set it up.

Mechanically im ok, been racing rc cars and planes for way too long..

Tail servo has full travel in each direction.
Motor is Align 430L 3550 BL motor 11t pinion
Battery is a mix of 2200-2400mah 12c
Deans fitted and adequate guage wires.

Orion when you say your tail hubs are set all the way over to the right doesnt that mean that the tail moves on the hub the
same direction of the Tx stick which is incorrect? (From my understanding). If i do this do I just reverse the gyro and tail servo?

The forum http://www.walkera-heli.com/forum/viewtopic.php?t=15 says that the Walkera cnc tail is leading edge however this is
not consistant with what CH said further back when I putting it on.

Thinking back now the heli was wobbling (not vibrating) in the only flight that I managed to get in on the weekend. CH could be onto something about tracking or something that has too much slop.

Cheers

Brett

Rattlecat

Brett,
I think something is causing a LOT of rotor drag. If I had that much blade deflection on mine, it would be piroing insanely fast. I only need a tiny deflection.

If your rotor is ok, try turning the blades 180* around in the holders, turn the blade grips 180* and reattach the balls to the tail slider, reverse the gyro and servo direction. Now it is setup for trailing edge deflection and the slider position will go twoards the other end of the shaft. I don't know how far, and that is the last resort solution.

Orion, Both belts are a Uniente B371. I will need to check the tooth pitch thing, but maybe one belt you compared is stretched or shrunk from being improperly cured in the mold.

I think I may start cutting my own sprockets, or trim them from industrial grade sprocket rod, but plastic sure saves weight when you can use it. I got a metal one for my belt drive FP experiment and it feels like a lead sinker.

CH

Rattlecat

Orion,
About the tail slider binding, I put an Align AGNH1141 tail slider assy on ($12) because it has dual pin drive. The single pin slider drive cocks the slider and makes it dig into the shaft. And it also has a hinged ball link arm. So far so good.
Those are also better for the gyro, it can stablilize the heli easier without the slider binding. You probably need a new tail shaft if it is scored.

I have my MX400 on ice until I get a set of HS-65HB's for it. Sigh, another $100. Oh, and I use an HS-56HB on the tail. I contacted Hitec and they said they use carbon brushes in their servo motors, not the cheapo wire brushes like in the Walkera 4 tail motor and in some cheapo servo motors I did a post mortum on. That would be why they can last for years. Not much motor spin going on in servo duty, just brush stress from reversing direction.

CH

Orion1024

Brett,

Moving the tail hub to the right has the same effect as the slider moving to the left, so it will actually give you more range for right yaw. Its still the same as the stock setup - slider moves left and heli turns right, slider moves right and heli turns left. I agree with Chophop that you shouldn't need that much blade deflection just to keep the heli straight. The first thing I would suspect is that either the front tail drive pulley is slipping or the tail hub is slipping. If it's neither one of those, maybe your belt is twisted and causing a lot of drag. Or, possibly the tail blades or holders are too loose and the blades are vibrating causing turbulent airflow and losing much of their thrust.