MODDING HENG LONG'S 1:16 TIGER

Heng Long Tiger ElMod

The Heng Long Tiger was my first radio-controlled tank, purchased shortly after I'd been bitten by the bug from online browsing. I've always liked the look of the iconic WWII German Tiger tank-- the Tiger had been my first 1/35 static armor kit, and it seems a natural first choice for a newbie RC tanker. Out of a desire to support the local economy and... well, actually I was too impatient to wait for an online purchase, so I bought it at the local hobby shop. That was probably a mistake, since there's no telling how long it had been there gathering dust.

UPGRADES, ROUND 1

The initial round of Tiger upgrades weren't elective; my store-bought Tiger had cracked suspension arms out of the box, so I ordered some fairly cheap metal ones. At that time, I wasn't really attuned to how expensive this hobby could be, so I was thinking that the most economical route was the wisest-- (relatively) cheap tank, (relatively) cheap parts. My first experience with modding the HL Tiger wasn't pleasant: The wheels were pressure-fitted to the plastic arms with aluminum pins: It was hellish to remove them, and several of the arms broke during the process (that did make the process go faster though).

Installing the metal arms wasn't much easier. First, screwing the arms and washers from the inside of the chassis was a real challenge because there wasn't room to use a screwdriver with adequate torque. My tank didn't have the metal side support rails in the chassis that I later learned had become standard in more recent issues by Heng Long. This meant that the arms would be held in place by washers against the bare plastic chassis-- not ideal for keeping the wheels aligned. To make matters worse, the arms didn't have allen screws to secure the wheel axles to the arms. Just like the original plastic arms, I had to pressure fit them on, by hammering the wheel axles into the arms.

I was not impressed with the engineering design behind these aftermarket parts and the fix didn't leave me feeling very confident about the long-term prospects for the tank. If it needed repairs or adjustment, I knew the wheels would not come off easily. Nevertheless, with Asiatam metal tracks, sprockets and idlers, it ran okay, so I replaced the turret with Creeping Death's hopped-up airsoft version with recoil & laser machinegun. I bought some 6mm glow-in-the-dark pellets and paintballs and played around with that for a while. Great fun! Then it was on to new toys, like the Tamiya King Tiger.

Infrared, Reconsidered: Initially, I'd thought that the infrared battling thing couldn't be nearly as much fun as firing real projectiles at stuff. I began to reconsider, mainly because of videos of Tamiya tanks showing synchronized cannon blast sound, muzzle flash and barrel recoil... very cool! This isn't actually an IR battling thing; it's really a shift in focus to a more authentic-looking/operating RC tank. 1:16 airsoft has limitations in this regard: The barrel's diameter has to be large enough for the 6 mm pellet, and you can't stuff a flash unit in the muzzle (since it would block the pellet-- duh!). While IR-configured tanks wear the goofy Dalek-esque IR detector, you can remove it when you're not doing IR battling.

My experience/experiment with Airsoft paintballs confirmed one thing: If you're investing time and effort into making the tank look realistic, you don't want to be firing paintballs at it! My Pzkpfw IV had been a paintball test victim, and removing all vestiges of the red paintball dye from all the nooks and crannies wasn't really possible except via a paint-over. Further playing around had left red spatters on my fence, tool shed, etc. that the garden hose and rain didn't wash away. So although I thought I'd leave one tank as an Airsoft shooter, I changed my mind and decided to sacrifice the Creeping Death Tiger turret to the IR conversion. Yeah, Airsoft was fun, but for blasting things with real smoke and sound, I have real guns.

My first Airsoft-to-IR conversion was Heng Long's Pzkpfw IV (so I'd have something to test my Tamiya King Tiger's battle system with). The conversion via Darkith's DBC went well and I'm very pleased with the extra features that the DBC adds, but I wasn't entirely satisfied; even if I were able to sync the recoil/flash/sound perfectly, that wouldn't solve the basic problem: the Heng Long sounds suck. I'd become much more sensitive to that after hearing the King Tiger's sounds.

UPGRADES, ROUND 2

Heng Long Tiger ElMod volume control
The volume control and on/off switch were moved to the rear during round 1 of upgrades. Some structural parts were cut off to accommodate the speaker since the original hull had a molded battery box; these had to be reattached to work with the Asiatam hull's screwless attachment method.

The Asiatam Hull: Upgrading the Heng Long Tiger wasn't going to be an easy (or cheap) job. Fortunately, at just the right time for me, RC Command began selling Asiatam's metal hull upgrade with metal arms, adjustable idlers, and torsion bars-- very similar to Tamiya's. Cool! This should take care of the drive train issues, and gave me hope that the Heng Long Tiger could actually be upgraded to the level of my King Tiger, and was worth investing with some serious time and bucks. Even though I got the package deal that included metal Late war road wheels, I wanted to model an Early/Mid war Tiger, so I needed to retrieve the original plastic wheels. Uninstalling them from the original lower hull was almost as much fun as putting them on the metal arms, except this time the plastic hull was splintered getting the suckers off.

The Electronics: I wasn't sure how I was going to handle the electronics. For a price, Tamiya electronics would have taken care of most of it, but I wasn't sure how much trouble and additional spending would be required to outfit the HL turret with recoil, flash and elevation. I was tempted to just buy the full option Tamiya Tiger kit and not have to think about it... but that would have been too wasteful and excessive, even for me. Maybe it was just sour grapes but I started thinking that I didn't want the Tiger and King Tiger to sound and work the same: I've got three tanks, so why not have them sound and work differently? This was a good excuse to investigate this "ElMod" thing that I'd heard so much about.

I did have questions and uncertainties about the ElMod system. In the forums, the boosters are pretty vocal about the features of the system, but there have been a few complaints about the newest board revision being a step backwards, about certain hopped-up motors burning out the circuits and about extremely short battery runs. I was willing to consider those as isolated cases (you can't believe everything you read on the Internets, now can you?). I was more curious about how well-integrated the ElMod system was. A tank that you cobble together through upgrades from various manufacturers is likely to present some compatability challenges for a third party system. (This is at the heart of the "Mac versus PC" thing that I've mentioned in my RC tank articles.) There are quite a few players in the 1:16 RC tank world, and very few standards.

Heng Long Tiger ElMod wiring
Round 1 upgrades also included the front upper hull tabs so that the tank could be disassembled easier (and to fix the alignment problem); Asiatam included a similar bit of hardware, but I'd already done my version (it explains the 3 hex heads on the exterior).

I had to relocate the rotation unit to the side to fit the original speaker box; this required grinding new teeth on the rotation ring gear, so as a side benefit, it turns 360 degrees. Unfortunately, the rotation unit housing was badly warped when I was trying to speed cure the mounting putty, and no one seemed to have a replacement unit in stock. Surprisingly, it works just fine so I haven't tried to replace it since.

 

Heng Long Tiger ElMod wiring
This shows the ElMod guts, floating in the interior. The boards are so light that they stay put under the tension of the wires, plus it gives them some movement flex, which helps in disassembly. Of course, there's always a danger of electrical shorts if the boards aren't placed properly, or have exposed traces in dangerous places.

The battery and speaker are the heaviest parts, most likely to do damage if they shift drastically and suddenly. I figure that if that happens, there will be plenty of other things to fix on the tank-- after all, it's a model. You wouldn't want to ship it this way!

 

The Recoil Unit: (I'd already finished installing the electronics by the time the recoil & elevation units arrived, which helped greatly in figuring it all out.) The airsoft-to-infrared conversion involved a bigger unknown than the electronics, since there weren't any instructions to follow, and the turret would need to be gutted of the Airsoft gun in order to fit a recoil unit. I considered 3 choices that I knew of: the Asiatam recoil & elevation unit (installed in my Pzkpfw IV, and I'm not very impressed), the Tamiya unit (good, but expensive), and the new Heng Long unit (cheap, but reportedly works well). I suspected that none-of-the-above would be a drop-in replacement, and that proved to be true.

A "realistic" recoil is one where the cannon sound and muzzle flash starts the cycle, the barrel retracts quickly, and more slowly returns to battery. I don't think any off-the-shelf stock units do this. With my PzkpfwIV, the DBC/Asiatam unit has the quick retraction, but the flash is triggered at the middle of the cycle (the momentary contact switch that triggers the flash is at the end of the barrel's rearward travel), and it's up to the operator's skill when or if the sound will happen. If you don't wait until the DBC enforces the reload delay, the recoil will still operate, albeit without the sound and IR beam. The stock Tamiya unit has good synchronization, but the retraction and return speed are identical (this can be "fixed" by an aftermarket mod which involves adding a spring and shaving teeth off of the main gear).

Thanks to the forums, I learned of an ingenious and simple modification of Heng Long's recoil unit. Basically, the unit is flipped backwards, with the spring pulling the barrel quickly backwards when the main gun is fired. The only tricky part is positioning a normally closed switch at the front (or end of the spring's fully tensioned travel) so that the motor stops and the recoil mechanism is "cocked" for the next time it's fired. Electrically, the recoil unit is soldered in place of the original airsoft gun (which triggers/runs the motor briefly when the cannon is fired), and a second source of power goes to the motor to run it (bringing it back into battery) stopping it when the momentary contact switch is tripped/opened. If the switch isn't tripped, the recoil operates continuously, which is not good.

This is a very reliable mod once the switch is properly mounted. The only downsides are the relatively short travel of the barrel and the somewhat loud gear sound of the mechanism (compared to the Tamiya recoil units).

The other challenge involved devising a mounting for the recoil unit, since it doesn't have trunnions (side axles) like the airsoft unit. I simply used brass tubing and sheets to fashion pivots and mounting so that the gun could be elevated. I moved the pivot points further forward than they'd been with the airsoft unit.

The Elevation Unit: I was pretty sure that I didn't want to use the original Heng Long elevation unit, since it takes up a lot of room and relies on a spring in the turret to press the barrel unit against the elevation cam. I ordered Heng Long's newer design elevation unit (which is similar to Tamiya's), but ended up using a servo. (This isn't entirely satisfactory either, but I had some electrical problems with the Heng Long unit that I didn't want to figure out.)

Structural Bracing: I added some brass bracing tubes across the upper hull to keep it from bowing in the center from the weight of the turret (which had lead weights added in the stowage bin area to offset the barrel weight).

The Speaker: The speaker came from a boombox, and sounded good and bassy after I'd housed it in a plastic butter tub-- very classy looking! This was the largest speaker I'd found that would fit, and I believe that speaker size does make a difference in bass presence (at least, it's true for guitar amps).

ELMOD ELECTRONICS

When I finally decided to take the plunge, I ordered ElMod's Thinktank v1.03 Panzermodul, Blaster3 module, the v1.00 CSI module; basically everything that was in the current product line except the (out-of-stock) Flash adapter, Configurator and the (not needed) Heng Long adapter. RCTankWars is the sole US distributor and the owner, Phil ("Blitz" on the forums) was very friendly, enthusiastic and responsive to e-mail. The website itself isn't quite as info-packed as the homesite in Germany, but it does have the full set of .pdf instructions in English and a FAQ section.

It's Easy, But... Installation of the boards was straight-forward, and the 2-sheet instructions (English with a slight German flavor) were pretty good. Although installation is easy, getting it to work properly can be the real challenge. The problem is due to the sparse troubleshooting information provided & what's available on the Internet. Two pages of instructions aren't really sufficient for a modular product that's designed to be used with other manufacturer's products. The website, although it has a fair amount of information, isn't nearly as helpful and up-to-date as it should be. The instructions have some notable omissions, references to older products, and not nearly enough detail about some topics. I wanted to make sure that I truly understood the product before installing it, so I searched for as much additional info as I could find. That was probably a mistake, since the information that's out there is pretty sparse and can be misleading. The English-speaking customer base is probably fairly small, so forums & Google don't have a lot of info, and the issues that are discussed are usually about older versions which often aren't relevant to the current version. Consequently, I learned enough unnecessary stuff to make the installation appear more complex and intimidating than it actually was.

Because of this, it's difficult to imagine someone with minimal troubleshooting skills easily installing this unless they have exactly the right not-included ingredients. Even though the new Thinktank Panzermodul is a much simpler installation than the previous TLS version, it's not as plug and play as Tamiya's. Tamiya has idjit-proof instructions for fitting their tank; it's also a mature and stable product with enough user commentary available on the Internet to help you through most any problem you might have.If you run into a problem with the ElMod-- for instance, an incompatible transmitter-- you're really on your own to troubleshoot and get it to work. Often, the support network folks (though well-intentioned), just don't know offhand. It's a bit like troubleshooting problems on a PC, when programs or hardware inexplicably stop working. In that case, manufacturers are usually not very helpful, but their customers are, and Google is your friend. In this case though, there aren't many English-speaking people out there who have the ElMod system, know it well, and have the writing skills and interest to present the info on the Internet.

It's important to be aware that ElMod is a small German company, and English isn't their first language. RC tanks are apparently much more popular over there than in the USA, and some really good customer-originated info is probably out there on the Internet-- it just isn't in English. That's unfortunate, since it's a complicated product and ElMod receives the "help me!!!" correspondence from customers, so they know what the questions are and are the logical ones to provide the solutions. While their website has FAQs that discuss solutions, it references boards that aren't in their current product line (TLS, Booster, Afterburner) and (at this time) very little is devoted to the current board, or even noting the distinction. It would be great if they provided a list of compatible transmitters/receivers, or known problems with popular but incompatible transmitters/receivers, even if it's in the form of reports from their customers. There really aren't that many 2.4GHz or 4-channel ground frequency transmitters out there, and keeping up with that would be in their interest. I suppose we should be grateful that the product is available though, and that instructions are in English-- I don't think many small US companies do as much for prospective German/International customers!

Is My Transmitter Compatible? My main difficulties involved the transmitter, a Spektrum DX6. As I've mentioned, info about compatible transmitters is conspicuously absent from the Elmod websites. RCTankWars lists 2 compatible models-- a Futaba 7C and an Eclipse 7 --but I wasn't going to buy a new transmitter when I had a perfectly good Spektrum DX6. The German website was a little more glib: They stated that they don't have the resources to test all transmitters, but most 4 channel transmitters should work, and that high-quality 6-channel transmitters should work-- but compatible transmitters should have a 3 postition switch or pot for channels 5 & 6 (which very few do). I was fairly confident that my Spektrum DX6 would work, since I'd got it to work with my Tamiya King Tiger. If nothing else, the instructions and FAQ claim that you can connect only 4 channels of a 6-channel transmitter and that the system will auto-detect the difference and let you operate your tank with all functions in a 4-channel mode. No problemo, right?

Unfortunately, it didn't work. I wasn't concerned that with all 6 channels connected, I had to figure out a workaround to get machine gun and cannon fire on channel 6, and that the headlights off/on function had to be sacrificed to get the tank to start up: This was due to the 3-position switch requirement that they mentioned. The bigger problem was that I wasn't able to get the transmitter's throttle channel to be used for barrel elevation. That receiver channel did work, since it could operate a servo, and barrel elevation did work when connected to another Elmod channel. It just didn't like the receiver's throttle channel. My solution of last resort was to use a servo with a slow-down controller for gun elevation, and live with the fact that it would always return to center when I let go of the joystick (because I had added a centering spring to the transmitter).

Of course, I tried the "connect only 4 channels" tip, and it didn't work: None of the special joystick positions worked, and I had a tank that couldn't be started up. Plan B bites the dust.

Around about this time (2 days later), I'd really regretted investing in the Elmod system, when the money would have come in handy for investing in another Tamiya tank. (Which I'll probably do anyway... [uhhh, make that did!])

The solution: I had narrowed down the problem to what looked like an incompatibility with the Elmod and the throttle channel of my receiver. What if I swapped the Spektrum AR6000 receiver with the BR6000 receiver I'd bought for my King Tiger? I didn't expect that it would make much difference since both had worked in the King Tiger... but I was wrong! The Elmod circuit worked!!!

It probably has something to do with the receivers' failsafe defaults, since that's the difference between the AR6000 and BR6000, as I understand it. In my opinion, that's not an obvious place to look for fixes when the newly-installed board doesn't work right and you have absolutely no idea what the problem is. Although I'm happy that I got it working, I'm a little perturbed that I spent 2 days of frustration that could have been avoided with this simple bit of info at their website, on the Internet, or anywhere, ie.: "Spektrum DX6 transmitters must use a BR6000 receiver to work with the ElMod."

Once I got the thing working as it should, I was much relieved and all my regrets melted away.

Thinktank Module-- The Drive System: The Elmod physics modeling (slow accelleration and braking) is fun and gratifying since it makes the RC tank drive more like a real tank (however, that's probably a liability for competitive tank battles). There are different configurations offered through jumper settings (plastic/metal/reduction gears, etc.); I set mine up for "Fun Tank" since it's the most responsive model. It's been noted on the forums that Elmod restricts current flow in other modes (for scale speed realism), but this can make the tank feel underpowered. The "Fun Tank" setting retains the full momentum modelling feature and noticeably more zippy performance.

The Elmod allows something similiar to Heng Long's "superspin"-- a "feature" that most folks loathe. You can avoid this by accellerating slowly, or turn it off if you buy their Configurator, which allows tweaking a bunch of other performance parameters.

Thinktank Module-- Miscellaneous: The Thinktank board includes a connection for the Heng Long 8-pin upper hull connection, which would seem to indicate that it's been designed foremost for the Heng Long tank. This allows operation of the standard Heng Long functions: Turret rotation, lights, main gun elevation, airsoft main gun fire/recoil and machine gun LED. The board's male socket is a minor hassle since a standard extension cable expects to plug into a female socket, and the hull-mounted socket doesn't have much of a reach. You can use their included screw-down terminals to make an extension, but I found it easier (and less bulky) to solder a Heng Long cable directly to the board.

The board includes a connector for a second set of optional lights and a muzzle "flash" LED. I'd originally planned to buy their Heng Long flash adapter, but found that Rctankwar's ultra-bright LED worked very well. Because the flash operation is controlled by the board, it triggers and turns off in synchronization with the IR emitter, recoil and cannon sound-- unlike solutions where the action is a cobbled-together interaction of discrete parts (like my PzkpfwIV's DBC/Asiatam recoil/Heng Long flash conglomeration) where the sound, recoil & flash are vaguely synchronized, where the recoil doesn't always correspond to the IR emitter flash, and where the LED stays lit for as long as a momentary contact switch is closed. ElMod's cannon fire sequence is a very consistent and uniform, like Tamiya's.

The board also includes a connector for two servos, as alternatives to the 8-pin connector's control of gun elevation and turret rotation motors. I had a small heli servo available, so I used that for gun elevation. I'm not really happy with it-- The elevation change is very slow, jerky, and only happens in a very small range of the left joystick's throw. I later tried to install a new Heng Long elevation unit, but had even bigger problems with its electrical interaction with the recoil unit (I think a diode is needed to isolate the two systems). Since gun elevation wasn't a big issue for me, I didn't spend much time figuring out the problem, and went back to the servo. I'd read that ElMod was working on a software update that allowed configuration of the servo behavior. This is a much-needed area for improvement since the left stick controls so many functions. It's irritating to have the cannon fire or the turret turn when trying to start up or put the tank to sleep.

The Sounds: The quality, variety and customizability of sounds is the main reason for getting the Elmod, IMO. The Blaster 3 card gives you a choice between 7 sound sets representing different tanks, stored on the removeable mini-SD card. The majority of sounds are devoted to stages of engine throttle and random wheel squeaks, but you can have alternate start and shutdown sounds in addition to staged turret rotation sounds (based on speed), barrel elevation, cannon fire, machine gun, IR battle-specific sounds, and 4 user-defined sounds sounds. A maximum of 80 .wav-format samples can be used in a set, which seems like a lot... but if you've got 40 devoted to throttle sounds, it's easy to bump up against the limit.

The best thing about this is that you can customize the sets-- they're not limited to the supplied default selection. You can have 7 different sets of Tiger tank sounds. For example, you can use wheel squeak sounds from another set; it's as easy as moving files within a directory and editing the .ini file to reflect the files' names. You can collect your own samples and make your own sets, or download sets that others have compiled. It's reminiscent of customizing computer games, the old-school way.

Naturally, the sound that comes out of the speaker(s) depends on the quality of the sample and your speaker, but the Blaster hardware is equipped with a beefy audio amplifier circuit and the sound samples are light years beyond what's burned into the Heng Long chip.

The Combat System Interface (EMBU?): The CSI/ElMod Battle Unit is easy to install, requiring only the included ENet ribbon cable. The only reading-between-the-lines that's needed for the current versions is that the ribbon connector only connects to the CSI board and the Blaster 3.0 board. The cable's terminal connector isn't used, but is part of the way that you connected the old Thinktank and Blaster modules before they were designed to be mounted on each other. The Apple and Emitter installation are no-brainers, but you do need to pay attention to the direction that the apple is plugged into the extension cable-- it fits both ways, and you don't want to risk frying anything (or waste time trying to troubleshoot it if it doesn't work).

For what it's worth, although the system is "Tamiya-compatible", you cannot plug a Tamiya apple into it: Different number of pins, different shape, etc. I only mention this because I thought I'd be able to use my spare Impact Battle Unit with it. I don't recall reading anything that said I couldn't. (Stupid newbie!)

The apple is a bare-naked thing: 4 IR detectors and LEDs mounted on a circuitboard & connector, with no housing. This is perhaps the most unfinished part of the whole package, and they don't offer the housing as an option. Without the housing, you can't do any serious IR battling (unless you like losing) because you can take hits from any direction and elevation difference.

In a way, that's indicative of the occasional "not-quite-finished" feel of the product-- Along the lines of the issues I complained about earlier, the CSI documentation refers to a "Tracker" system that uses magnets to detect the turret's orientation for determining the type of damage in the battle system's extended mode. From reading the documentation, it seems like something that was intended to have been included, but it's not-- and it's not to be found anywhere on their website either (as of 08/2009). I've heard that it's something they used to include, and that the functionality is supplanted by the 4 IR detectors & software on the chip. (But that's just something I heard...)

The CSI module has two jumper-selectable modes: Tamiya-compatible, and Elmod's own proprietary mode. The Tamiya-compatible mode should need no explanation; the Elmod mode is a considerably extended version of the basic Tamiya battle system. The extended mode is cool, and allows for one-shot kills and a variety of different damage types: tread damage, turret damage, etc. The only problem is that for a fair battle, all the tanks you're battling should be running in this extended mode as well, or you'll get clobbered for showing off your bag o' tricks.

In Tamiya compatibility mode, you face a few disadvantages as well (in addition to the naked apple)-- When you take a hit, your tank stops dead in its tracks. Due to the realistic momentum physics, it will take you a bit longer to get to that bit of cover that you were racing towards... which may be plenty of time for the enemy tank to hit you again, and again. All you have to do is convince the other guys to play by the same rules that your hardware enforces!

Verdict: The ElMod system is an attractive alternative to Tamiya electronics. It's definitely more full-featured, with a lot more control options. Although you can install a Turnigy servo speed control in a Tamiya to simulate starting and stopping momentum, the ElMod system is more sophisticated and highly tweakable with their optional Configurator. Their system also includes programming for braking, so that you can stop quickly if you need to. That can be a very important feature if you don't like running into walls.

Also, on the ElMod, the lights on/off & shutdown/warm start functions are available through 4 channels (although crammed into the left joystick), leaving 2 totally free channels on a 6-channel radio, for whatever your creative mind can dream up. In the Tamiya with a Spektrum DX6, those two features would have to be "modded-on" and mapped to channels 5 and 6.

Although you can customize the ElMod's sounds, I must say that I think Tamiya has nailed some excellent sounds for their King Tiger: They're loud, and all the different effects cut through the mix very effectively. In theory, you should be able to do this (or better) with the ElMod, but in practice (even with downloaded collections), I haven't heard any that I liked better than Tamiya's stock sounds. There are more gimmicks, odd creaks, alternative start up sounds, etc., but I don't consider them superior, and some of the unique sounds that initially sounded cool get old and irritating (like the absurdly long startup sound currently in my Tiger) when you hear them repeatedly (That's why I dislike sound effects mixed with human voices). That said, I stick with my original assessment that it's more interesting to have two tanks with two different and distinct sounds than two with identical sounds, as long as the sounds are good.

MODELING

Heng Long Tiger ElMod I'd wanted to model my Tiger as... uh... a gray one! A true WWII-o-phile would probably sneer at this as a starting point, since it's more classy to choose something demonstrating historical knowledge like "Abteilung 502 at Kursk, blah, blah ". Nope, I wanted a gray one, and my rudimentary knowledge of WWII history (frum lookin' at pickchurs) told me that this might be required to be a early to early-mid war version. Fortunately, the Heng Long tank came that way (except mine wasn't gray when I bought it), with early war rubber-rimmed tires, a drum cupola, 2 headlights, the turret-mounted smoke launcher tubes, etc. I didn't mind this stock configuration since I didn't want to mess with Zimmerit-- but I did want to add turret-mounted tracks for looks, and remove the Feifel air cleaners at the rear because they hindered accessing the tank's innards. I did find an illustration vaguely meeting these guidelines, so I figured, "good 'nuff".

Details: I was more concerned with the accuracy of small details than historical accuracy. Most of the gross turret problems were taken care of by using the Creeping Death turret-- they'd fixed the reversed mantlet direction and the orientation of the cupola and pistol port. I replaced the barrel and muzzle brake with aluminum parts because they were better-sized, with a more to-scale bore size. Elsewhere, from looking at pictures, I found lots of little inaccuracies to fix, like the driver's vision port and the angle of the rear storage bin. I didn't bother fixing the turret mounting position, or the fact that turret should be slightly asymetrical. The molded-on tools looked pretty funky, so I grinded them off and replaced them with those from sprue "D" of Tamiya's Tiger (Having a .pdf version of the Tamiya Instruction manual was very helpful!)... in addition to a few other goodies that were included on the sprue. I soon realized that Heng Long had simply not included some bits & pieces, like the jack crank, or the cupola hatch support. I initially thought that Heng Long had simply copied Tamiya's Tiger-- there's a lot that's the same, or very similar --but I found enough differences (like the hull machine gun port shape & wooden jack block detailing) to make me wish that I could have bought and grafted the Tamiya upper hull and turret onto the Asiatam hull and ElMod electronics. It's a lot of work to grind off tools and cut hatches. Not that Tamiyas are perfect, but it's hard knowing that you wouldn't have to do this if you'd bought theirs... especially when you don't know if for all the work, you're just polishing a turd. (That's something you figure out later, after you've developed a refined eye.)

Painting: Painting a tank gray is a very different challenge than painting a tank in a camouflage scheme. Initially, I thought the tank looked fine just spray painted with gray primer- plain & simple. However, I didn't feel like I'd really painted it, so with the goal of making it look more realistic, I added some different shades of gray by airbrush and attempted a dark brown filter using oil paint-- a technique I'd heard about but never tried. I guess I wasn't doing it right because I wasn't happy with my results, so I went back to using acrylic washes, pastel chalk and Dullcote. Lots of streaking, dark areas to bring out detail, and chipping/rust painted on. I may have overdone it, but I was much happier with those results because I felt like I knew what I was doing.

The decals came from a generic sheet made for a Panther(?) of unknown scale. The largest ones happened to fit nicely in the little spot beneath the smoke launchers. I chose the red numbers because I thought that they'd give the gray-everywhere look a little bit of contrast, but they were waaaay too bright! An airbrushed mist of dust and brushed pastel chalk made them blend much better.

The hardest part of this "beyond primer gray" paint job is that it's difficult to match paint for a repair, reworking, or if you add a new part. The original foundation color is altered in both shade and hue, so you have to futz around until you find something that's close and try to blend it in.

AFTERTHOUGHTS

Just One More Thing... What about the drivetrain? This souped-up Tiger had the original Heng Long metal gear transmission and stock motors, which worked okay but the sprockets were making a little track noise and the tank seemed a little underpowered. I fiddled with the gearbox a bit and discovered that the housing was really flimsy: the metal tracks were exerting a lot of stress that was deforming the housing, and causing an alignment problem at the sprocket. The solution? Spend more money. I knew that Impact gearboxes were very sturdy, so I bought those instead of getting some upgraded ones that were made for Heng Long. After I'd ordered them, it dawned on me that the Impact gearboxes were made for Tamiya tanks, and they might not fit! I test-fitted Heng Long sprockets on a Tamiya gearbox: Close, but not quite. Must order Tamiya Tiger sprockets! Are the mounting screws the same size? Nope... must order mounting screws! When the gearboxes arrived, I discovered that they didn't include the mounting standoffs-- I panicked for a while (since they're not an orderable part), but figured out that I probably didn't need them (The drive shaft locations are close on the vertical plane and the Heng Long gearboxes don't use standoffs). Fortunately, the Asiatam metal tracks fit the Tamiya sprockets, so I dodged one additional expense. Lesson learned: They may look the same, but it doesn't mean they are... so be prepared to spend... and improvise!

Heng Long Tiger ElMod Impact gearbox
Once you've got all the parts, then the fun and anxiety begins: How do you make it fit so that the drive shafts end up where they should be? The first step is to think of how the thing can be assembled back in the tank. My plan: The gearboxes need to be mounted to the mounting plate, but since you can't count on screws being accessible from the topside (if you use Impact's mounting holes), the gearbox will need to be screwed to the mounting plate from the underside. You'll need to find screws that fit the holes (I had a mongrel collection of screws), and aren't too long (to jam the gears) or too short. You can't assemble the gearboxes to the mounting plate and screw that assembly to the hull, so the gearboxes will need to be mounted after the mounting plate is installed in the hull. That means that the hull will need to be drilled with access holes so you can insert a screwdriver from the underside to mount the gearboxes to the mounting plate. This isn't the only way to do it, especially if you drill new mounting holes in the gearbox and have thread-cutting tools, but it's a relatively simple and straight-forward way to do the job.

Make drilling templates of the new gearboxes' mounting holes (I used clear acetate). Note how far from the chassis the drive sprockets should mount relative to the mounting plate (using the original gearbox), then extrapolate that to the new gearboxes' shafts (with the new sprockets attached). The idea is to make sure that the new sprockets are properly aligned with the wheels and idlers (and don't assume that the Tamiya sprockets fit on the shafts to the same depth). Next, note or measure the vertical distance difference from the mounting plate, so that the new shafts are roughly in the same location, vertically: In this case, the new gearbox only needs to mount 2-3 mm higher than the old gearbox-- it's not too critical, and happily, this will also give clearance to the two gears that protrude below the base of the Impact gearbox. I used thick brass strips as shims to set this height. After all this noting and measuring, place the new gearbox on the mounting plate so that it's aligned according to your observations, and mark the location of any mounting holes and guidelines you can access. Align and secure your drilling template with your marks and make some holes. Note: You won't be able to use all the template's holes since some are too close to existing holes in the mounting plate. Also, some holes won't be usable once the plate is mounted in the tank since the torsion bars run underneath. Install the mounting plate in the hull (without gearboxes), select the mounting holes you'll use and drill through the hull. Remove the mounting plate, place the screws and shims (lightly secured with contact cement so they don't fall out), remount the plate, place the gearboxes, screw them securely from the hullside access, and cover the access holes (with tape or self-tapping screws)to prevent dust intrusion.

 

Heng Long Tiger ElMod Impact Transmission Unit
After it's done, you can add additional shims and supports to ensure that the gearboxes are secure and positioned properly. The front ends of the gearboxes aren't secured by screws and "float", so they benefit from shimming. Also, it's a good idea to add a crossbrace across the top (not shown in pic) to minimize inward/outward flexing. It's easy to make a crossbrace by cutting slots in brass tubing and slipping the tube over the inner walls of the gearboxes.

The Impact gearbox solved the flexing/alignment problem of the original's thin profile and soft metal housing, which fixed the drivetrain alignment and eliminated the sprocket noise that I'd identified as being indicative of an alignment problem.

The original Heng Long gearbox in conjunction with ElMod electronics gave about the same speed as the King Tiger fitted with Graupner 400s in a 3:1 Impact gearbox. Replacing the Tiger's gearbox with an Impact 3:1 gearbox (with Tamiya motors and brass pinions) slowed the tank down, making it noticeably slower than my King Tiger. Honestly, it's not as much fun to drive, but it does give it a convincing "lumbering giant" quality that looks good and is super easy to drive. Variety is good.

 

Conclusions: An underlying theme of this article has been the dreaded debate of "Heng Long versus Tamiya versus DBC versus ElMod versus Godzilla, etc.". This issue is of interest to folks who like to tinker, and are in pursuit of making their RC tank the best it can be, or better than it is. I dwell on it because it's relevant for me, and judging from the frequency with which it comes up in the forums, is relevant for many people involved in the hobby, at one time or another. It's relevant because we're faced with choices when we buy RC tanks, and when we decide to upgrade them. I deliberately explored the 3 main choices for tank "operating systems" because I was curious-- it would help determine my choice for RC tank # 4. (Of course, you can't stop at just 3!)

At the heart of this debate is the issue of priorities: Is it about functionality, money, or both? If money's not the most important issue, then it's less complicated because you can focus on the features you want.

If money's the overriding issue, then the discussion starts with the difference in the basic building blocks: Heng Long tanks are cheap and Tamiya tanks are expensive. However, it's not that simple. To upgrade a Heng Long to the level of a stock Tamiya is expensive. However, upgrading Tamiyas (which is fairly common) is also expensive. It's not simply a matter of Heng Long parts being cheaper (which they generally are)-- but parts vary in quality, are interchangeable (with some degree of hacking) and are also made by aftermarket producers in exotic foreign places. Buying high-quality German-made parts is expensive, whether they're for a Heng Long or a Tamiya or a hybrid. The difference in basic building blocks boils down to how you want to spend your money. With Tamiyas, you spend a large chunk of money up front. With Heng Longs, you spend smaller amounts incrementally. If you do it incrementally, overall, you'll probably have to do more work, waste more parts, and may even spend more money.

That's not to say that the work is a bad thing, since that's a big part of the gratification that some people get from the hobby. Making a square peg fit in a round hole can be fun. If you're really skilled and have the tools and supplies, you can save money by scratch building stuff.

A features-guided approach is less complicated, but not necessarily easy. I believe it does narrow the choices though- If you've ever heard a Tamiya or ElMod equipped RC tank, any system that retains the Heng Long sound system is out of the running-- sorry! (at least for me.) I suppose that's the threshold for "Tamiya snobbism", although I believe that it's not strictly about Tamiya: For me, it describes a performance level, however you get there. Therefore, I've restricted my choices to the two most popular systems that are similar in functionality and price-- Tamiya and ElMod. For realism, features, variety, and flexibility, the ElMod system excels. For robust operation, rock-solid reliability, and guaranteed long-term support, the Tamiya system excels.

The wrinkle is that the Tamiya system is sold with the tank, whereas the ElMod system is just the electronics. You can buy the Tamiya electronics separately for about the same price as the ElMod system, but if you spend more money, you get a complete tank with quality construction and decent drivetrain. Of course, if you've already got a modified Heng Long tank that you want to fit with Tamiya electronics, buying just the electronics will be cheaper than buying the whole kit, but you'll need to adapt the electrical sockets and plugs to work with your chosen "peripherals".

The ElMod system appears to be intended to upgrade Heng Long tanks (they accommodate Heng Long's 8-pin plug). If you have a Heng Long tank that you're upgrading, you'll probably want to buy drivetrain-related upgrades, and the original guts won't fetch much on eBay. If you're fussy about the detailing and don't want to scratch build stuff, you'll spend money and time fixing the things that aren't right with the tank's exterior. In contrast, if you have a Tamiya that you want to upgrade with ElMod, you'll probably recoup some money from sale of the DMD units, but you'll have to figure out how to make the recoil & elevation interface with the ElMod electronics, and probably have to replace the flash unit with Heng Long's, or use an LED. You'll also have to do something about the ElMod IR detector apple, since it's pretty naked and you can't plug the Tamiya apple into their CSI system socket.

I've mentioned these scenarios because they're relevant for my situation: I've been eyeballing Tamiya's Panther as a prospective RC tank #4. Although Heng Long will be coming out with an improved Panther soon, I'm pretty sure that it won't be as nice as Tamiya's, based on comparisons of the Tiger Is and Pzkpfw IVs, and I don't want to be "nickeled and dimed" to bring it up to that standard. I do like the idea of installing ElMod electronics though, mainly so that the tank would have a distinct sound, momentum with brakes, and for the spare channels on a 6-channel radio system. As I mentioned though, I'm not too fond of their IR apple (although I plan to do something to dress it up properly). Also-- while the ElMod does drive more realistically than the Tamiyas, in my opinion, it's not quite as much fun: Scale realism doesn't always equate with fun, and it would be nice to have the option to dial in your preference. I think this is something that ElMod could fix with a chip upgrade.

Based on this, there was a predictable outcome: Between the last paragraph and this, I ordered the Panther. The ElMod isn't out of the equation though, since I could use the Tamiya electronics as sale fodder to finance the ElMod, or trade it for a Pzkpfw IV DMD and buy and the ElMod... Hey, the Pzkpfw IV needs some love, too! The opportunities to spend money seem endless...

Heng Long Tiger ElMod

 

Interestingly, cameras can see things that human eyes can't, like the light from the IR emitter (mounted in the mantlet), activated as the cannon fires. I was surprised at how long the LED stays lit; I expected a brief blip.

Also notice that the left stick controls lights, startup, elevation, rotation, machine gun and cannon fire, so it's not easy to do one thing without triggering another. In this case, the turret rotates briefly as I try to wake up the tank and the machine gun fires as I switch the lights off. I did manage to put the tank to sleep without triggering the cannon though.

Just for fun camera test: A tank's eye view, using a palm-sized Sony MHS-PM1 camcorder. The quality of the wireless video and the super-small USB 5in1 eDVR that I've used before is really bad, and the Nikon's way too big and heavy to sit on top of an RC tank (It's also difficult to use at tank's eye level). Sony's camcorder has a hinged lens on the top so it can lay flat on the tank with the LCD screen facing upwards. These two vids were shot at VGA resolution.

This long-ish video plays the protracted "cold start" sound at the beginning. The tank can't be driven (although turret, cannon, machine gun, etc. work) until the sound is finished playing. The other video shows the much shorter "warm start" sound.

Both vids were taken before installation of the Impact gearbox.

 


 

SHEESH, IF I'D JUST BOUGHT A TAMIYA TIGER IN THE FIRST PLACE...

I wouldn't have had nearly as much fun!

06/13/13- Aging Sucks! It's almost 4 years later, and I've been checking in on the current state of the hobby and checking out my old tanks. Amazingly, all my batteries still charge and hold their charge, and I'm mightily impressed with myself for figuring out how to use my fancy charger. Some of the tanks took a bit longer to figure out: I remembered how to take them apart to put in the battery, but figuring out where I'd concealed the "on" switches and volume pots was another matter. Yeah, you can take them apart again to look at the wiring, but where's the fun in that?

It's instructive to see what works and what doesn't after a long period of inactivity. Based on my experience, I'm inclined to say that generally, the built-by-the-book stuff is more reliable than the modded stuff. The Tamiyas ran great, but I did undo the recoil modification on my King Tiger since it wasn't working reliably. Similarly, the Asiatam recoil in my cobbled-together Panzer IV needed disassembly-level coaxing to work as unreliably as it used to. I had to disassemble the Tiger to get its modified Heng Long recoil assembly to begin working again (thanks to my funky home-brew installation).

Basically, when stuff sits for a long time, springs may stretch, parts may drift out of alignment, or get temporarily frozen in place. When I figure out clever ways to splice parts into a Frankenpanzer, I confess that I'm just trying to get the sumbitch to work, and I'm not thinking about whether it's a smart design that's going to work 4 years down the road.

There's something to be said about going with the tried-and-true. Tamiya tanks have a deservedly good reputation. They may be expensive and short on the glitz factor, but they're reliable. ElMod on the other hand, has the distinct cachet of a science product from some really smart guys who love radio controlled tanks. As such, they're inclined to explore the outer limits and come up with some really cool shit. That's great, except sometimes the enthusiasm leads to products that are not mature, and may have some growing pains.

Trouble in Tigerland: Of course, I'm talking about my version of the full ElMod package of about 4 years ago. It's obsolete now, and they've released newer "ECO" and "PRO" versions. At the time, I was very impressed and very happy with it, willing to overlook some of its flaws like the anemic power and wonky servo-controlled barrel elevation. The awesome programmable sounds made up for it.

Four years later, it still sounds great but something's amiss: The anemic power thing seemed to have gotten worse, and it has an overheating problem. I removed Impact's drop-down gear hoping to pep it up, but it wasn't happening. Even running it for the sounds, without motors, causes overheating in a short while: Some chips on the board get toasty, paper-charringly hot. Evidently, something in its electronics has failed. Finding a Fixit Yerself solution wasn't happening, since relatively few English-speaking tankers have ElMod boards, and if they do, they probably have the newer versions. Odds are that few have the deep knowledge to fix an electronic problem.

I considered upgrading to the newest version. This would have been a spendy prospect, and I must confess that, considering my experience, I now feel a little leery about investing so much moolah in a product that has such skimpy English-language documentation and such a conspicuously silent base of English-speaking users and supporters. Heck, I seem to recall the ElMod website having more FAQ-ish stuff 4 years ago. It's a small niche hobby that doesn't seem to have grown much in 4 years, so the support base hasn't expanded, especially for esoteric products from small producers. In fact, there appear to be fewer USA sources for RC tank parts in general than there used to be. So... I have a Tiger without working guts, and I want to fix it with parts that will likely work 4 years down the road, with good support in case I should run into problems or need replacement parts. The logical and safe choice seems to be Tamiya guts.

UPGRADES, ROUND 3

Heng Long-Tamiya FrankenTiger RC Tank 1/16

Messy, but it would be worse if it had the wires from a battle system coming from the turret. The wires going to the upper hull are for controlling the lights and the laser machinegun. The lights circuit has a Ninco slot car lighting board to regulate the voltage from CN6 (around 7 volts); I had a spare and was too lazy to make one without the gold cap, so it provides that interesting but useless feature (in this context) of powering the lights for a while after you switch off the power. I used the upper hull's pre-existing manual switch instead of a receiver-controlled Pico switch because it was easier and reduced the lower hull's tangle of spaghetti wiring.

Heng Long-Tamiya FrankenTiger RC Tank 1/16

Amazingly, it all fit with plenty of room to spare, even with the kludgy "I Can't Believe It's A Speaker" margarine tub (which works surprisingly well).

Guts of the Tiger: I already had a spare Tamiya DMD multi-function unit (MF01) and elevation mechanism, so I bought a DMD T03 ESC/receiver interface (harder to find now than 4 years ago), Tamiya flash unit, and recoil mechanism. I kept the Heng Long turret mechanism since it works well and seems to be more robust than the Tamiya mechanism.

Most of the installation was very easy since I had 2 other Tamiya tanks and my build articles to reference for receiver connections, including the Pico switch installation for putting it to sleep/wake up. It also helped to have a supply of the 2mm Micro-Latch Molex connectors for making plugs to the Tamiya MF01. I'd already modified the MF01 to connect an external volume control and done the circuitboard shunt to use the laser machine gun. I even found an odd gizmo that fit in-line with a transmitter channel; it turns out that it's a non-adjustable momentum simulator, much like the Turnigy Speed Control.

Heng Long-Tamiya FrankenTiger RC Tank 1/16

The mantlet-mounted IR LED was left with (red) wires bundled up and not connected. Someday I may splurge on an IR receiver. (Note the turret's lead counterweights on the bottom plate, underneath.)

The Tamiya Recoil Mechanism: The only real work was fitting the recoil and elevation units in the gutted turret. Both systems demand some degree of precision in installation planning for a gutted turret. The recoil unit needs to be mounted securely to the mantlet at the correct angles (vertical & horizontal), and distance to allow the barrel to traverse the correct amount, smoothly and straight into the mechanism without binding, pulling to the side, or encountering excessive friction. I used copper sheet to make the mount and barrel linkage since it was stiff enough to stand up to the forces exerted by the recoil mechanism but maleable enough for trial-and-error prototyping using tin snips and needle nose pliers. (As I later discovered, not quite stiff enough for the force of ramming a wall with the barrel!) Once I had a design that could be securely mounted to the mantlet, I manually cycled the mechanism to locate the screw holes to secure the mechanism to the mount, noting the start and end positions of the barrel's recoil and making sure that it stayed in horizontal and vertical alignment. (I got it right with the second set of holes.)

The Tamiya Elevation Mechanism: The elevation mechanism posed a different set of challenges. As with the recoil mechanism, I made the mantlet lever/arm from copper sheeting, cut to what seemed to be a reasonable length, shorter than the length of the recoil mechanism. I had absolutely no idea about the calculated distance and travel it would need to produce the proper limits of deflection at the mantlet, but I knew that the large white plastic gear on the recoil unit shouldn't grind against the top of the turret. Just to be sure, I grinded out a small gouge in the turret since the mantlet's range allowed it. I used piano wire for the linkage and experimented with several lengths and shapes, along with defeating the mechanism's travel end-stops.

It took quite a bit of trial-and-error since the mechanism has a lot of slop and gravity plays a big role in how it operates. This was an inconvenience since the tests had to be conducted looking up into the turret instead of laying it on its side. My main frustration was in my inability to visualize and understand how the linkage would act during its travel along the rotation arc. During my first experiments, the barrel's traverse would pause and suddenly drop when the linkage reached the peak and the "slop" suddenly asserted itself. I thought the slop was in the plastic lever that attaches to the linkage, so I drilled a tiny hole through the steel pin and lever (and my finger) to pin it in place: No dice. Apparently, the slop is deeper in the gearbox. After I got tired of puzzling over this, I reinstated the end-stops (to avoid the problem of the drop from the slop), put a soft spring between the elevation mechanism and the recoil mechanism (to assist with the weight balance between barrel and recoil mechanism) and made a longer linkage with a bend in the middle. This seems to work reliably and uses the entire range of the deflection that the mantlet allows. Still, I'm fascinated by the problem since it seems that there are so many possibilities for design, and I'm sure there's an optimal one. I just can't use my intuition to visualize it.

The Battle System: What battle system? I just want to work on it, drive it around, stick it on a shelf, wait for four more years, and fix it again! As I mentioned earlier, the hobby seem to be sort of moribund. At this time Tamiya battle systems aren't in stock anywhere (except a few on eBay from China) and it seems like online retailers have been waiting for delivery for a while.

So... Is It Gonna Work Four Years From Now? (If I stop running into walls, maybe...) Tamiya parts are reliable and seem to have stood the test of time. How they're mounted and modded is another story. In my experience, home-brew solutions, or "mods", or "kludges", are generally less reliable, particularly when it comes to mechanical things. For example, a servo-taped momentary contact switch isn't as reliable as one that's optimally located and screwed down into a made-to-fit spot on the housing by the manufacturer. Copper sheeting mounts are more maleable than the stamped metal parts Tamiya includes in their kits, and they design and position the parts so that they work best (or at least better than mine.) When you do Frankentank projects, you make do with what you've got and hope for the best.

If Only I Hadn't Had That First Beer... It's true that the ElMod system had more bells and whistles than the Tamiya and I do wish that this tank didn't have exactly the same sounds as the King Tiger. That's not so hard to accept though, since the Tamiya tanks have great sounds. The other stuff is even easier to accept: I can live without all of the features crammed into the left stick of the ElMod 4-channel setup since controlling them was always quirky and iffy. The cannon elevation was slow, unresponsive, hard to find its neutral point, and often led to inadvertently triggering the cannon and machinegun. I couldn't turn the engine on/off without triggering the cannon fire. The Tamiya setup is much easier to control. With the addition of Pico switches, lights control and warm startup/shutdown are easily mapped to the gear and flaps controls on the transmitter.

I've travelled an especially inefficient and costly path to arrive at what turned out to be a Tamiya Tiger mutant clone. With hindsight, it would have been much smarter to have bought the Tamiya kit in the first place. However, this was my first radio-controlled tank, and I wasn't willing to spend that kind of money. The Heng Long tank was like a gateway drug: Reasonbly priced to get in, and then the addiction grows. At first there was some spending to fix its cheapie tank problems (blown board and broken tracks shortly after purchase). Then came the small upgrades, then more expensive upgrades, then buying Tamiya tank kits, and now, this. I don't see how it could have gone differently. At present, there are no regrets, just the gratification of a successfully completed project. It was an interesting and fun (at times, frustrating) learning experience.

 


 

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