DIY: 4G6 Crash Proofing and Performance Enhancing mods! Updated 27July2010

[timewerx]

Details and links to the mods are below the disclaimer.

Please read this, very important:

Disclaimer:

I will not be held responsible for any injuries, damage to your heli, voiding warranties, property damage, and casualties inflicted by this mod for any reason including the following:

-Improper replication of the mods i.e. did not use recommended material, did not precisely follow measurements.
-Not assuming an attitude of safety in proceeding with test flights after applying my mods. All the mods below may affect the handling of the 4G6 to such extent you may need to revisit both your mechanical and electronic setups.
-Using other motors than specified. These mods has only been tested with the stock motor (both KV11000 and KV10000 versions) and with HP08-2 1S up to 20T pinion using stock Walkera ESC. The mods has not been tested yet with high performance motors such as HP08 2S which will produce higher RPM and higher risk of rotor components, including the mods, flying a apart at max rpm.
-Using defective stock parts. Make sure your stock 4G6 has been fully flight tested in full stock configuration to ensure everything is working.
-Using defective materials. Ensure that all materials you use, including glue had the highest quality for these mods
-Do not apply my mods to helicopters other than the 4G6 (or maybe the Novus CP125 too)!!
-The experimental and DIY nature of these mods mean this is not by any means professional work! Just by doing these mods, you are accepting the risks in the pursuit of making your 4G6 a better product. Even if you did everything by the letter, there are still chances of failure although very small, but it's still there! Proceed at your own risk, you have been warned!!



The following mods will make the stock 4G6 the only fully crash-survivable CCPM helicopter model in the world yet, while also improving the performance at the same time!!

Please click the following pictures to take you to the step-by-step instructions, thank you!


Compatible with: 4G6(S), V120D02, and 4G3


Compatible with: 4G6(S), V120DO2, and 4G3


Compatible with: 4G6(S), V120DO2, and 4G3

Compatible with: 4G6(S) and 4G3


Compatible with: 4G6(S), V120DO2, and 4G3


Compatible with: 4G6(S), V120DO2, and 4G3


Compatible with: 4G6 and 4G3


Compatible with: 4G6(S), V120DO2, and 4G3


Compatible with: 4G6


Compatible with: 4G6(S), V120DO2, and 4G3


Compatible with: 4G6(S) and V120DO2



Compatible with: 4G6(S) and V120DO2


Compatible with: 4G6(S) and V120DO2


Compatible with: 4G6(S) and V120DO2


Compatible with: 4G6(S) and V120DO2

Indoor Cyclic and Collective test with all the mods applied



Thanks to all Helifreak members who gave useful feedback in refining my mods, and those who
donated to keep me flying! You know who you are!

[dizzymarkus]

Would it be easier to make the mods to the tail drive shaft end instead?



Markus

[timewerx]

Originally Posted by dizzymarkus

Would it be easier to make the mods to the tail drive shaft end instead?

Markus

I've already thought of that, it won't.

If you pull the tail drive shaft, and most likely, you will if you try to remove the tail end bevel. You will have to remove the landing skid and main gear in order to replace it to the front tail gear. Conversely, you'll have to do the same if you apply the mod to the front tail gear.

Also, the carbon shaft wears much faster than the metal tail shaft. You'll find re-tightening the gear much sooner than if you've done it on the metal tail shaft.

Maintaining the tail shaft bevel, you never need to remove landing skids and main gear unless you accidentally pull the shaft bevel

[dizzymarkus]

cool ty for the info -- I was "thinking" with you lol

Markus

[timewerx]

Lol! Yea, it's a puzzle really.

I think with a little more sophistication, you can turn these into very reliable system designed to hold itself up in the inevitable without the weight penalty.

Hopefully, I could adapt these mods to bigger sizes as well. But I got nothing such atm.

P.S. I think I did it at the right time!, my LHS ran out of stock of the tail gear set and this is my last good one!

[Steve Joblin]

Your ingenuity is amazing!!! Great stuff! You do an incredible job documenting and describing your great ideas! Keep it up! Please... Keep it up!!!!!!

[JBuck]

One question,

In the gear mod, why cut the plastic tube in half? and after cutting it why keep it there? Doesnt the tube keep the right bearing in place by pressing against the left gear? After u cut it is it doing anything being there?

Thanks,

[raptorddd]

i aslo have another question in the gear mod the plastic gear hole has a shape where one part is like flat is this what we need to take away how can i know how tight or loose should it be.??
very good idea
thanks timewrex

[timewerx]

Thanks Steve! After all, you're the one who got me into this mess!

I was looking for the most crash-resistant CP, 4G6 turned out to be one of the most true enough. But it's crash resistance isn't enough for me, two broken blades a week, and one tail gear, for me, that's much!

Originally Posted by JBuck

One question,

In the gear mod, why cut the plastic tube in half? and after cutting it why keep it there? Doesnt the tube keep the right bearing in place by pressing against the left gear? After u cut it is it doing anything being there?

Thanks,

True and great question!. But we don't want folks by-passing this step as it can be potentially catastrophic to the handling of your 4G6!

Since we rounded off the tail shaft bevel gear, the tail shaft no longer stops at the gear. Something has to stop it so that it won't drift to the left and cause actual tail drift during flight or worse, complete loss of tail control. Static tests have demonstrated this shaft drift in no time even with the complete plastic tube in place!

This is when we use the plastic tube(spacer) as a stopper instead - together with CA glue. We cut in half otherwise, it would make a huge mess if you try to squeeze CA glue to it and it will stick to the bevel, and worse, spread to the bearings.

And now since, nothing is stopping one bearing from falling out, we also need to CA glue it too but in very small amounts so when you need to replace the bearing, it won't take much effort to remove it.

To sum, do not bypass that step, it's quite vital to avoiding loss of tail control in flight.

[timewerx]

Originally Posted by raptorddd

i aslo have another question in the gear mod the plastic gear hole has a shape where one part is like flat is this what we need to take away how can i know how tight or loose should it be.??
very good idea
thanks timewrex

No problem, yes, you're correct, it's the flat part.

For me, it's wasn't very tight at all. Tight but easy enough for the bevel to be turned around the shaft with my two fingers and of course, if I try to turn the main gear while keep the tail rotor from spinning, the bevel slipped and the front tail gear didn't strip.

Take her up for a test flight, if the tail hold is solid despite how insane the rudder inputs you give, then you got the tightness right

If you got it too lose(causing bad tail hold), put exceedingly tiny amount of CA glue, let dry for some time and finally, free the bevel gear with your finger from the shaft by turning around the shaft, make sure that you didn't over tightened it. Conversely, you can use the CA glue method for maintenance as the gear will get lose over time from crashes and vibration.

It may take some trial and error or you may also try a bit loose with bad tail control and very slowly add CA glue until the tail becomes solid in all aspects of control.

[JBuck]

Makes scene.

Great!

Thank you

[JBuck]

OK,
I removed my other half. I told her to pack her things and get out. I than went flying and crashed but I still stripped a gear.

What am I doing wrong?

lololololol

[timewerx]

You definitely removed the wrong half!

I think you've set the bevel too tight or possibly, some CA glue went to the bevel - avoid that situation!! You should be able to turn it around the tail shaft easy enough with your fingers. The point of the mod is that the bevel slip around the tail shaft during crash instead of stripping the front gear. Go back to Step 2

If it's stripping, cut more material off the bevel so it becomes lose so the front gear won't strip anymore. Don't over do it though.

[raptorddd]

this is the best mod of all.
thanks timewrex.

I removed my other half. I told her to pack her things and get out. I than went flying and crashed but I still stripped a gear.

What am I doing wrong?

guess she didnt left at all.

wouldnt it be easier to see a video if it isnt too much to ask.?
to see how tight it should be.

[timewerx]

Originally Posted by raptorddd

this is the best mod of all.
thanks timewrex.



guess she didnt left at all.

wouldnt it be easier to see a video if it isnt too much to ask.?
to see how tight it should be.

Gee thanks! But it is for a good reason, other than curbing the costs, I never know when I leave one place so ordering parts online is very risky for me. Back at home, ordering will cost you a lot more than you can imagine, there are no LHS back home that supplies 4G6 parts either. I almost regretted purchasing my 4G6 until I succeeded with the mods! Also, it will be much faster to learn if you're not fearing of a crash(except for 3D, maybe tough crashproofing against a high speed inverted crash that may involve the mainblades striking the tail boom!)

Regarding the video, I would if I can, but the video capability of my camera is as bad as my piloting!:o

I think even if I can show by video it still wouldn't tell how tight it is... We need a torque meter or something!!

But maybe this could help (I actually tried it so don't laugh at yourself doing it!):

-Remove the rudder servo rod by the servo and pull it all the way forward - this should fully feather your tail blades(maximum pitch)

-Blow as hard as you can over the tail blade tip while holding on to the main blades or main gear so it won't spin. You should be blowing towards the direction of the nose. Now, if the tail shaft slipped or tail rotor rotated, you've set the bevel too loose. It should be just tight enough so the tail rotor don't move or spin if you blow real hard against it.

-Or you can try a vacuum cleaner in reverse or a dust blower to blow air against the tail , see that the bevel is tight enough not to slip or spin the rotor - also try this method on a non-modded gear and see if it doesn't strip the front gear, if not, then a dust blower will be a good basis of tightness!

-Or you can also try the CA glue method, begin with a loose bevel. You will have a huge loss of tail control initially, then very little by very little add, CA glue(and free the shaft after glue dries so it doesn't stick to the bevel!) until the tail becomes solid. You'll do this later anyway even if you got this mode right!

-I hate to say this, but also due to my lack measuring equipment atm, if what I say above fails, then it's left to trial and error (again we go back to step 2). You may lose one or two front gears in the process but once you got it right, it will be Christmas everyday!

[timewerx]

Also please make sure the main gear isn't lose against the front tail gear (someone here suggested this before, I forgot who)

If it is lose, adjust it via the main shaft collar. Because if it is lose, you will likely strip the front tail gears as well as have a bad tail hold.

[Badmedicine]

Something I noticed today, while taking apart my 4g6, the tail boom would slide in and out of the main frame probably an 1/8th inch, replaced the screw in the frame with a slightly longer one, being careful not to crush the boom when I snugged it down, the other thing I noticed was where the main gear meshes with the tail gear, didn't have much contact, it was just barely meshing with the very edge of the tooth of the gear, there is a nub of plastic where the main shaft goes into the main gear that hits on the lower bearing, I filed down the nub, just a little at a time, until the two gears meshed properly, now the main gear is getting a full tooth bite on the tail gear. The main gear still lines up with the drive motor pinion fine, it just moved from the bottom half of the pinion, to the top half of the pinion. Now if my main shaft would come in, I could test it

[timewerx]

Originally Posted by Badmedicine

Now if my main shaft would come in, I could test it

You mean crash-test it? I hope you don't!

The safest way to test it is prevent the tail rotor spinning with your hand while you turn the main gear with your other hand without the battery in the helicopter. The bevel in the tail shaft should slip instead of stripping your front tail gear!

After 5 crashes now(without stripping the front tail gear and only a little dent on the main blade, woot!), I need to re-tighten the bevel now. A little drop of CA glue, seems to be working - just force-turn the bevel around the shaft after the glue dries to prevent binding - and cause your front tail gear to strip again in a crash!

[mprasm]

You will crush that boom eventually if you tighten the screw. Especially from crashes or vibe. On the other hand, you want that boom to be clamped down tight and not move back n forth. Cut a tiny piece of elongated plastic (usually from hard wrapping shell) and put it in between the screw and the boom. The screw will press on to the hard plastic and the plastic will bear the pressure/friction instead of the CF boom.

[timewerx]

Incredible, thanks Mrprasm! I could use it too

It's one of the glaring design flaw from Walkera, I dunno if other manufacturers adopt the same practice. Although the square boom is a big improvement over their circle boom. The square boom could take the pressure of the screw much better than the circle one like on my 4#3b.

What Walkera could've done is glue a hard plastic that would cover a significant front portion of the boom, and give it notches that would fit the screw. Unfortunately you can't do such mod because it won't fit. The closest is what Mrprasm gave advice.

The key to a strong graphite attach is glue, not screw!! I've learned this lesson from my other hobby - badminton. I've never seen a graphite shaft attached to the racket handle and the neck by screw - screw that! They use epoxy! Imagine smashing the racket on a hard cement floor or your team mate's racket without damage, it's incredibly durable!