Heng Long Tanks - Advanced Modifications

[tomhugill]

I look forward to seeing what you can do. Whilst many of us don't have access to the really shiney workshop toys it's nice to see what can be done with them! Guido and Edwin have posted some marvellous work in this vein and it's nice to see some more!

[ALPHA]

I'm Sticking to my guns on the points raised on bearings....as I do believe Weight is a contributing factor and that by installing bearings you weaken the "host" part
in other words by over boring the hole to accommodate the bearing...you thin out the wall of whatever you are installing it into ...there isn't much there in the case of a wheel....thus causing a imperfect mount for the bearing...causing it to wobble in the bore...the extreme trickle down effect would be the bearing fails because of improper rotation ....and ovalizing of the bearings themselves

Bushings on Lighter tanks work fine...are easy to change out ...and cheaper than bearings...addressing the issue of plastic to metal contact.... I have tanks over six years old that haven't showed any signs of bore enlargement...and even if they did...sliding a brass bushing in addresses that issue without having to purchase another set of wheels

PROS AND CONS to everything... in this case ...I do believe weight is a factor

ALPHA

[ALPHA]

An added note.... in RC cars.... the situation is different.... Weight is still a factor... but what is different is the Speed...cars move at greater speed...so the friction coefficient is higher....the "HEAT"...will change the composition of most plastics... reason bearings are better than bushings or surface to surface contact ...So in Cars Speed and Heat are deciding factors

Application changes with vehicle ....you might run a Car full out for five minutes and feel heat on axle points...do that with a tank...NAH

It's actually one of the reasons I like tanks

ALPHA

[CanadianBulldog22]

ALPHA,

Good point.

[CanadianBulldog22]

I decided not to cover my topics in numerical order. Next up, Topic #5.

Topic #5: Brushless Conversion

Dc brushless motors have always been a good replacement for a conventional DC motor if you want any RC vehicle to go faster. This is nothing new to any of us. I feel there are a few things that can be done to ensure the conversion works on a dependable level. The problem that I found was heat build up inside the tank chassis. In most rc cars/trucks/planes there is a certain amount of air that passes directly over the motor to take away heat. Heng Long completely seals the chassis of its tanks (I assume for keeping water and dirt out). This heat has no place to escape and the motors overheat quickly. I installed a CPU fan on the rear side of the tank and created some filtered air vents so i can pull all the hot air out of the tank, I also like the look of the fan on the back. (Those of you who are more into it looking authentic will object, and that is understandable)

Now that I have discussed my opinion on overheating. I now want to list the motor specifications I found during my research. If you guy object, please let me know.

Equivalent Brushless Motor

28 mm can diameter (380 size equiv.)
3.175mm Shaft
10 tooth, 48 pitch pinion gear

A KV of around 2000 on a 3S lipo will make it fly.

Also, if mixing the two channels is beyond your radio, or if you want a more stable solution. I use a v-tail mixer from my older rc glider. A v-tail mixer basically takes two servos, automatically mixes the signals so that the elevators and ailerons of v tail gliders work together. It also has the advantage of being able to control 2 brushless motors on tank tracks. The aileron function of a glider is basically the same as pivoting around on a tank, two servo like devices running in opposite directions. This isn't necessary, you can just mix the channels on your own radio. If you are using the stock radio, this doesn't work.

I will post some pictures soon.

Chris

[CanadianBulldog22]

Follow Up,

If you can find a SENSORED brushless motor that would be the best scenario in my mind. For anyone who has used a sensored motor before, they have amazing torque and no cogging. This means you could still move at a crawls pace with the tank. The downside to the upgrade I discussed above is that the non-sensored brushless motors require a minimum rpm before enough back emf if generated to sense the rotor location. (Google back emf, brushless motors for more info).

The only company i found that makes a sensored motor that will fit without major mods is this one by Novak. I couldn't find one anyone for a reasonable price.

http://www.teamnovak.com/products/brush ... index.html


Chris

[Merlin707]

Hi Chris, just seen your response to my initial post, thank you for changing it and thank you for sticking with us.

Reading through your thread I'm sure you will be a valued member for the knowledge you are offering.

You have a private message too.

Liam

[ALPHA]

If you bore the hole correctly, you should have no wobble....

Yup...that's the key....thing is not many have steady hands to drill a consistent hole in how many wheels with a hand drill....and not many have a drill press...so there is a greater chance of irregularities than perfect bores ...not to mention you are still thinning the surrounding material that was made for bushings or surface to surface contact...which means you are changing the tolerances set by the factory

as far as weight is concerned, you will not have enough weight on the tank to have any "Structural" effect on the wheel or suspension.

Yup that's what I've been saying...reason I said if the tank is under 12lbs ...there is really no need to install bearings...over that ...it's something to be considered because of the added drag........( the added weight )

when a Bearing is installed correctly the weight is distributed in the hub, not just on the bottom as you would believe. the plastic in your tank is a lot stronger than you think, unless you bore your holes out to the point where the shoulder of the hubs are less than say 10 thousandths of an inch, you will not have anything to worry about. On another note, most conversions to bearings require two bearings for each hub so side loading is not an issue either. Remember, the tank is supported but how many axles? if the tank weighs say 20 lbs or 10kilos and you have 18 axles like the King tiger has, then your loading per hub is .5 kilo per axle or 8 ounces US, so really do you believe your going to rip that bearing out of the hub? or cause the hub to create an out of round condition? Now you could argue that when an axle goes over something and it flexes there is more torsional loading, sure, maybe another .5 kilo of weight total 1 kilo felt by that axle... Remember no matter what you are distributing weight throughout all the axles.

On another point, bearing also allow a better reaction to the inertia, if you have a clark board you know what I mean, the tanks don't just stop, they will kinda coast to a stop...

Hope this helps you guys that were thinking of getting bearings.. Cheers!

OK...A little redundant...but that's cool...but basically what is written in this part is common knowledge or just plain common sense...bottom line for me is...these 1/16th scale tanks are toys... no matter how you look at it they are toys ...sure you can improve the workings with insurmountable degrees of upgrades...it would really depend on the owner what is practical and what is not...it's a toy...toys will break no matter what....if you took a stock Heng Long and poured a thousand dollars into it...it doesn't change that it is a toy tank....If I were to consider all the time and mathematics to improve upon someone elses design...I would go the route that others have gone... and design my own tank...like what Saxon does...that way you can rest assured the design will last
This way of boring out plastic installing things that weren't meant to be there is "BAND AID" stuff....a real improvement would be to machine your own wheels axles etc...so tolerances can be kept at a realistic level...and you do not WEAKEN any stock parts....you have to remember the host foundation...that is ...a good percentage of the structure is plastic
So if you are really serious..... do it right..make your own parts so you can apply the proper measures so nothing fails

Yup that's pretty much it...reason I'm sticking to my guns

ALPHA

[ALPHA]

Follow Up,

If you can find a SENSORED brushless motor that would be the best scenario in my mind. For anyone who has used a sensored motor before, they have amazing torque and no cogging. This means you could still move at a crawls pace with the tank. The downside to the upgrade I discussed above is that the non-sensored brushless motors require a minimum rpm before enough back emf if generated to sense the rotor location. (Google back emf, brushless motors for more info).

The only company i found that makes a sensored motor that will fit without major mods is this one by Novak. I couldn't find one anyone for a reasonable price.

http://www.teamnovak.com/products/brush ... index.html


Chris

Hey Bulldog.... you have to do a Search...look for some of another member EDWIN...his builds are just on another level ...much higher than your average builder.....He did a thread regarding brushless motors...it was really laid out well....once going over some of his posts...you will find he is not the run of the mill builder...the guy is a craftsman...machines his own parts...after evaluating stock parts... could be any brand ...even asiatam when it comes to the gearboxes

Anyway...what he did to maximize and stabilize the performance on the brushless motors was to add a flywheel to the opposing side of the stator..he had videos of the performance of his design .... it was really impressive...you really should try taking a look at some of his posts

ALPHA

[brizo58]

Hi All,
You say you were in the RC cars in the 90's . I myself was there in the late 70's so a bit more time then you. As a few chaps have said here there is a lot of very experienced model makers on this forum who know how to upgrade and make there tanks and other RC models more efficent. Well that's my two bobs worth. Brian...