YHR

As there has been much interest about the mods done to this gun I have prepared a quick little tutorial.

First picture shows the Heng Long recoil unit. In the picture I have already removed the plastic that would normal rest on the Heng Long rotating cam elevation unit. As I am now using the new elevation unit I know longer require this. I have drawn in the outline of the plastic that was removed.



THis picture also shows the bbl inserted into the rear of the gun. Doing this means you don't have to make any mods inside the gun or reattach the spring.

Second picture shows the recoil unit with a contact switch in place and the necessary wiring to get it to work. Also I am using a graphic to represent the gun motor, which is not visible in the picture.



So let me explain what is happening in this little circuit.

1 Power is supplied to the gun motor from the smoker jack. The resistor (20 ohm)drops the voltage to the recoil unit to slow down the return speed.

2. The power is routed through the contact switch on the gun. In its current position the contact switch is closed, and the power is fed from the HL board to the motor. If this was hooked to a battery the gun motor would be running and the gun would be moving back to it's fully extended position.

3. As the gun extends the contact switch is tripped open by the returning striker(A). As soon as the switch is open the power is interrupted and the motor shuts off with the bbl in the fully extended position.

4. To fire the gun you move the left joystick. A quick blip up. This supplied power to the motor, moves the gears to release and allow the spring to pull the bbl back. As soon as this happens the contact switch on the gun closes, and power for the smoker jack is allowed to power the motor again, and the cyle repeats.

If you wanted a gun flash, you would hook up a superbright LED with the short lead to the yellow wire, and the long lead to the Brown wire.(Add a 68 ohm resister to protect the LED. When you blip the throttle up this will power the LED to simulate a flash(Of course if you hold the left joystick up the LED will stay lit and not look very convincing. However all you need is a momentary connection to start the recoil motor and this works fine for a flash.)

That is all that is required to mod the Heng long recoil mechanism to achieve the results I demonstrated on the Sherman.


I won't bother talking about the internal gun mods, as they are not required if you use this alternative. However a tutotial was done on RCuniverse by someone else ,and in that, it describes all the internal mods that are required if you don't want to , or can't use this gun 180 degree from what it was intended.

Red/Black/Black 20 ohms should work. However you need to be aware of the current capacity of the resistor. IF you use a 1 watt 20 ohm resistor you should be good. Or I have recently learned if you took three 68 ohm resistors and wired them in parallel you would have a net resistance of 22 ohms that could handle three times the current. I harvested this resistor off of a HL ESC.

You know where to find me if you have any questions.

Update. Just wired this up in my stug. Wouldn't you know it the Heng Long smoker jack has red as negative and black as positive. So use a volt meter to check the pins before you wire it up. In my illustration red is positive.

borealis

Very well explained, thank you

rgallant

Thanks ! excellent work.

sjgusmc21

YHR, thank you very much for taking the time and pictures to explain this! I just finished installing the Asiatam unit in my Tiger I, all in all very easy with only a few glitches there were figured out. I have one of these units and will put it in my next project. Where did you get the relay at? Radio Shack? And I know you mentioned this, but what is the 'new' elevation unit? Thanks again and truly appreciate all the help and guidance you give here on this forum!

gigantohawk

Great tutorial...saved to favorites.

sir_francis

What recoil sysetem is it? I've asiatam one for Tiger 1.

YHR

I thought the title would have given it away!!!!!.. It is a Heng Long recoil system.

calvinlo

Thanks for the pictures - they really help!

Just a question - I've not tried it yet, but I wonder, When you reverse the recoil unit, I suppose you also need to switch the elevation unit to the other side? If so, it is difficult to do so and secure it?

YHR

Yes, unless of course you turn it upside down as well. Haven't tried that, but it might work.

I am not sure why, but when I wired up my stug I had to add a diode at the motor to prevent current getting to the flash LED when the motor was running. When I drew this up I caught that, but because my Sherman never had this issue I assumed the Flash LED was doing its job, but on the stug this became a problem. So if by chance you find your Flash LED energized when the motor is running you may have to add this diode.

sir_francis

From title I thought it was a recoil sistem for heng long not once produced by heng long. I've never seeon one of these.

YHR

I'm sorry, I was trying to be funny. Yes these are the relatively new recoil devices. THey first appeared on the Stug, but you can buy them for retro fitting if you want.

sjgusmc21

YHR, can you tell me where you purchased the contact relay? Is this a standard 'Radio Shack' item? Thanks again for the tutorial.

YHR

Yes I bought it from Radio Shack, or the source as it is now called. I removed the metal lever.

fsciorelli

YHR

I just noticed bubbajoe put a similiar tutorial on the rccomand website. Can you comment on how your method compares to bubbajoes? Are they complimentary? Are there differences in functionality? Thanks

YHR

The first person I know that hi-lighted this was 971wright. That was months ago. My first 4 upgrades were done basically the same except for the capacitors on the motor. I never did anything to mine, so I am not sure about the "Noise" the bubba refers to. I just haven't had an issue with mine.

What I recently discovered though, is if you run the bbl out the "back of the gun you don't need to even take the gun apart.

So the mods others have done are easy to do and the results are great. My Sherman is exactly done that way. However now that I know you just flip the gun 180 and run the bbl through the back, I question the need to bother with this other mod anymore. I just did my stug and the results are the same with very little work.

If you were planning on the old cam style elevation unit, then you might want to consider this earlier mod as you would need the plastic ramp on the back of the gun. The orignal way also allow you to keep all the mounting the same. So I think if you were moding an existing tank then maybe the effort to do the internal mods to keep the mounting the same is worth it.

The one issue I have had with the internal mods, is you have to ensure the bbl doesn't go to far back, otherwise the gear will not engage the rack on the block, and the motor will just run with no recoil action happening. I had to then add a stop to the inside of the gun to always make sure the gear would engage the rack. Not sure if bubba addressed this, but you need to be aware of it as you may find that as a problem of this mod..

If you are however doing a kitbash or scatchbuild I think I would be tempted to flip the gun as it is the easiest thing to do

My Stug and Sherman were kit bashes so I wasn't to concerned about the stock mounting points.

So you have two choices to improve the Heng Long recoil, and probably two different unique circumstances to consider before deciding on which one works best for you. .

sjgusmc21

YHR, thank you again for taking the time to post this tutorial. Yourself along with Bubba and others have really helped me (and countless others I am sure) to understand and make great modifications to our vehicles. It is kind of funny, as I have no problem setting up a RC Heli, airplane, boat and even a 6 foot submarine, but man, when it comes to these HL tanks, the tutorials, examples, and guides that you guys have given have helpe me TREMENDOUSLY! Not to mention lowering the costs of some items, such as this $11.00 recoil unit! Just wanted to say thanks again! Stacy

fsciorelli

YHR,

Thanks for a good pros/cons description of the two methods. I am rather green in the hobby, so I would lean towards bolt-ins and minor mods, versus full up kit bash/scratchbuild.

sir_francis

Very low price. I spent much more for asiatam recoil system.

Dmon1996

Just want to bump this how-to up to the head of the pack. I just used it last night and it works wonderfully! All I can add is to be VERY careful on microswitch placement. I finally got mine just right by wiring it all up and testing while holding the microswitch in place with a c-clamp (lightly). This way you can adjust to get an instant jerk back without the inertia carrying the block past the release even though the switch is clicked off. Once satisfied, run the crazy glue in between the switch and the recoil unit.

YHR

The 20 ohm resistor should slow the return rate down to make the microwitch set up much easier. I found without the resistor, the momentum of the gun carried it past the microswitch, and the thing would just fire constantly

Alard

I went one further and split the resistor into two 10 ohm resistors. One was connected between+Supply and the motor,and one wasconnectedbetween the ground and the switch contact that returns the gun to battery.
Thatway, there is only 10 ohms in thecircuit that moves the gun forward til it releases, and 20 ohms in the circuit that returns the gun to battery. This was done to make sure that the slight forward movement of the gun on firing was less noticeable, and the recoil happened more quickly, the return is a little slower. It looks pretty good, except my KV-1 jumps so hard that it's hard to see unless you lift the tank off the ground.

cmpang

Thank you YHR for such a good tutorial. I have just completed the mod. here is some video:

Before the mod:

http://www.youtube.com/watch?v=rF5IlfPl5Uk



After the mod:


http://www.youtube.com/watch?v=dV5v03ooiCk

Alan123

Great mod well done.

I just hope Mr Heng Long gets hold of this and starts making his recoil units correctly from the start to save us all the trouble of having to mod our tanks. Not to mention that he might thereby improve his product and its appeal.

That KV1 movie before and after was very convincing.

Cheers

Alan

YHR

Glad you could use it.

I have taken all the pictures I need to do a tutorial on extending the travel of the Heng long. Just need to find the time to put words to the pictures. My latest Sherman Firefly has the extended travel. This does involve taking the gun apart though, so more in line with Wright 971's original gun mod modified to extend the travel on the block.

cmpang

Great to hear you have extend the recoil travel. I also attempt the extension but found that the travel is limited by the position of the catch in the last gear. Actually it is the diameter thus the perimeter of the last gear that determines the travel.

Please post the details when you have finish the description....