| At
this point, I thought of re-connecting up the electronics and to give
the thing a trial run to see how it moves. First up is to have
somewhere to mount the stuff, so the floor (pack 17) is temporarily
held onto the
chassis brackets (pack 16) by a couple of bolts per bracket. In order
to stop
everything
sliding about, I dry-fitted the seats to the floor and held
down
the electronics units with some small pads of Velcro and held
the
cables away from the tracks with tape. Not pretty, but functional. And
not wishing the whole caboodle
to shoot off the bench when first fired up, I knocked up a stand from
some old bits of wood, just to keep the tracks off the surface. Having connected everything, cautiously, hooked up the 2 x 12v main and 6v Rx batteries and switched on the transmitter, checked all sticks and trims neutral, then the main power switch. A hum from the steering servo, nothing more (which is good!). First the steering - which, as you have seen in Stage 3, is already proven, and here still works (more good!!). Do the tracks move? Yes!!! But the wrong way - in reverse for forward stick. Easily cured by the Tx servo reverse switch - on this model, located under the battery cover (everything switched off again before doing this). This time the tracks move in the right direction. And correctly go in reverse with stick down. Next, try left/right stick. As they should, in forward motion the outer track slows (and with enough stick, reverses), so we have correct set-up. Oh no it isn't ! That's the wring way round as well, so with the track steering channel also reversed, finally we have correct track settings. Finally the winch. Earlier, I'd found that one of the cable connectors in the switcher unit was faulty, and Electronize had kindly posted a spare connector block, which I'd just fitted. And then obviously messed up re-connecting the cables, because in neutral, the winch just kept on winding in ... and in and ... which immediately proved that the gearing was slow (a few mm per second) but incredibly powerful and switching off the power was the only to stop it! After a quick swap of the +ve and -ve supply to one of the relays, and resetting the neutral adjustment - with the winch motor safely disconnected this time - the Tx can now control the winch in and out. With the model moved to the floor (no mean feat with most of the heavy parts are now on, however loosely), I gave the model a first run on tracks. The first impression was that a barn would steer better, as the front wheels don't want to turn (steer) with the batteries in the up-front position - maybe Armortek know more than I do. With the batteries moved aft, the wheels can be turned, but I feel the provided servo is barely up to the job. Track steering, on the other hand, is easy and since the mixer and motor controllers give a good, linear and smooth response to the stick, steering is (relatively) precise. Ok, so this was on a hard smooth surface of the garage floor, what about the great outdoors? First negotiate the car parked in the drive (this model could do damage!), then onto the front lawn. Well, I call it a lawn, others may call it a mossy bank, but that's for another hobby I'm not so good at! Runs ok on this surface too, though less ability to spin on the spot than on the smooth concrete. A couple of runs up and down the road, and back into the garage, as its getting dark. The next day was spent jury-rigging a ramp to get the beast into the back of the car without causing serious damage (to me, the car or the model, in order of decreasing importance and fragility). And the day after, heading off the the club's Combat Zone to 'show off'. Pity only Tony and Jim where there - still Jim, who's also building the same model and is ahead in the build but hasn't yet installed the motors, could see how his model might perform. The photos below were taken after a few more runs around the front garden and road. You can see that some of the rubber pads have disappeared. From the remains, most have actually worn away, rather than just fallen off (though some of the lost pads may have come unglued). These losses mostly occurred on the rough asphalt driveway. Replacements will be from the thicker parts of that el-cheapo rubber car mat and I'll try contact adhesive instead of superglue... |
|
|
| So,
did we survive the first runs? Dismantle the electronics, remove the
tracks (which impede access to the topside build) and lets have a look.
Ok, so some of the rubber pads need replacing, and two or three
(ex-sewing) pins have come out. All easily fixed. The front steering is the weak area though. I mentioned back in Stage 3/Pack 10, that the brass axle-ends were not going to last long just glued in place as per the manual, so I'd opted to put a 3mm bolt though. While the inserts were held place, they were never solidly fixed, and in running I could see them wobble. Movement like this is never good news, and eventually is going to get worse, so something more drastic is called for. Others, as I noted before, have used silver solder. I don't have any and I've never tried (or needed to) use it, but let's see if ordinary lead/tin electrical solder will work - nothing to lose. I dug out a small butane torch I hadn't used in years, and there was still gas, so packing some solder into the axle end, jamming the brass insert back in place and held with the bolt, I heated up the joint and added a little more solder to the outside then let it cool down. Seems solid. I'd drilled the first bolt holes a touch too big, so now I've re-drilled at right-angles to the original holes and been more selective of my drill bits to give a very snug fit. Hopefully this combo will hold. Even if the solder joint is no permanent weld, at least it's taking up the internal gap and should stop the wobble. But not only were the inserts a tad sloppy, but due to the twisting force on the steering arm screwed into the left axle block, the arm just wouldn't stay tightened up, despite having locking nut and thread lock on it. This combination of looseness was impeding the full steering action, stopping the wheels from turning right entirely, though it was OK when the arm had been tightened up (again). More attention needed, so I've now also drilled and pinned these arms. At the same time, I re-adjusted the external steering lever connected to the servo a little forward of vertical, as the arm was hitting the gear casing before full right lock. Now there's equal turn in each direction. We'll have to see if these modifications stay tight. Finally, I've adjusted the steering channel rate throw on the Tx to reduce full lock a little, so nothing mechanical prevents full steering movement. So, if the model design has a weak area, it's got to be the front axle and steering arrangement. The brass axle end inserts just don't work as advertised, and Armortek should reconsider reworking them in steel and welding them in place, as they do for the spot-welded parts of the axle yoke. The twisting forces on the steering arm, being pushed and pulled (the pull is in the unscrew direction) from the steering rod from above, with such movement assisted by the ball-joint, also needs to re-thinking. Or if the hardware is unchanged, to modify the manual to give better guidance on fixing these parts. |
| First the
sound module. This is a Benedini
sound card and amplifier
housed in a metal box, a loudspeaker and speaker mounting plate (which
also mounts the smoke unit, of which more later), plus all connecting
wires. The unit is powered from the common 24V system, and the track
motor speed and steering channels connect from the
receiver
to the sound unit and thence on to the motor mixer control. A third
connection can be make from a spare Rx channel as a control to the
unit. I've moved the winch control from right stick up/down to a rotary
knob on my Tx and use the stick for the sound control. There are 12 possible effects, and flicking the stick up X times selects the X-th effect and flicking down once triggers that effect. (This is the default control method; extra hardware can be purchased to select the effects by other means.) |
 |
| 1. |
Engine
start/stop (flick once to start and flick again to stop. The engine
continues to sound until stopped, so the other effects can be
super-imposed.) The engine (and track squeaks) vary with the motor
speed, as varied by the Tx throttle stick
|
| 2. | With sound #1 on
and the Tx trottle stick at neural (engine idling), briefly revs the
motor. |
| 3. | Explosion |
| 4-8. | Machine guns (various calibre) |
| 9-11. | Radio voices (snippets of German) |
| 12. | Horn (a pity this isn't swapped with #3, as for this vehicle the horn is going to be well-used, and selecting #12 is tedious...) |
| Since
a picture of a metal box is rather boring, clicking on the sticky
label (right) will download an MP3 recording of the unit running
through all
the effects on offer (effect 1 start/rev up/rev down/idle/stop and
twice each for effects 3-12). This was recorded using a PDA which does not do justice to the real sounds produced. Also, to prevent complaints from indoors while testing, the volume is turned right down - max. volume is not for indoor use! |
 |
|
| The smoke
unit is basically a machined metal box with lid, filler and exhaust
pipework, 24V heater element and holder with a carbon-fibre mat to soak
up the smoke fluid (baby oil works well, I'm told) and a small fan to
push the smoke down the exhaust pipe. The fan connects to one of the
drive motors, so varying the smoke in sync with the model speed.
Alledgedly. All of the smoke unit parts are shown here in the main picture; the insert shows the unit temporarily set up and running. As you can see, there is no shortage of fog! Baby oil does indeed work well - and no, I'm not going to explain why we have a bottle of baby oil lying around when our 'baby' is now 26!!) |
 |
| The above
test showed that a little smoke leaked from beneath the lid and the
exhaust
pipe joints. It goes without saying that smoke will pour out of the
filler pipe unless a bung is fitted (not supplied). So for final
assembly, I put a fillet of glue around the top of the smoke box and
around the filler and exhaust pipes where they exit the lid, and
soldered the elbow and coupling in place. The smoke unit mounts on the base of the speaker bracket, as shown here. The front face is painted black so as not to show up behind the radiator grill. |
 |
| At this point, before the smoke/sound units are finally installed, the radiator grill was prepared and fitted into the housing. The grill needed a little filing to fit flush, then the slats were bent evenly about 45 degrees, as per the manual, painted and bolted into place, as seen here. The inside of the radiator housing could do with being painted back too... |
 |
| And here we
have
the smoke unit/speaker mounted as per the manual. By
the by, this position rules out having the batteries in the engine
bay... It's not obvious where the sound unit should be mounted - the manual doesn't say. If in the engine bay, then the servo leads are too short to reach the Rx in the 'boot', and if in the boot, then the speaker cables are too short. Initially, I've mounted it on the front face of the bulkhead and have three long servo extension cables back to the Rx, with Y-leads between Rx and motor mixer (DMR-203). The box is held in place by (a) the middle bolt that fixes the dashboard to the other side of the bulkhead (at a later stage) and (b) the middle bolt that holds the front floor to the bulkhead. (I've since moved it to the right-hand side panel, as I plan to install a servo on the bulkhead to move the steering wheel.) |
 |
| To finish off the option packs, we need to install the exhaust pipe. This comes as a coil of 8mm copper pipe which needs to be bent into a rather complex shape. The route I took, from front to back, was under the bulkhead, between the motors, to the right of the winch and out the back stretcher. Trying to bend this pipe by hand is sure to result in kinks, so I bought a small 6/8/10mm hand pipe bending tool from a local DIY chain store which did the job very easily. The photo on the right shows the bent pipe (from the side and top) before installation... |
 |
| ...and the pipe on the model. Here, I've painted the pipe a rusty colour, not that most of it will be visible when the model is complete, but bright copper wouldn't be very authentic! At the time the photo was taken, the sound unit had gone back to Armortek (see above), but the pipe really does fit under the box. You'll notice some sticky pads and cable clips to keep the pipe from rattling. |
 |
| The end of the pipe - which will be visible - has been given a multi-coloured rust job and a smoke-blackened look. This photo shows the smoke unit and fan powered up for good measure. For this test, the fan was connected direct to the 24V supply - when powered from the motor feed, I expect the volume of smoke will be less. |
 |
| UPDATE! After some
reported fan failures, possibly heat-related, Armortek can supply a
nylon stand-off to insulate the fan from the smoke box, which I've
duly installed. More recently, further fan failures have apparantly
been reported; I suspect these are due to them being driven from the
motor supply which is a chopped DC not kind to inductive loads like the
fan motor windings. Also, this method of driving the fan has
limtations: (a) it needs almost full throttle to get the fan turning,
and (b) the fan doesn't work when the motors are in reverse. Both limitations are (partially) overcome by a new gizmo which Armorteck call a "rectified fan". This consists of a two components stapped togther (see photo): a diode bridge - which ensures that whichever way the motors are turning, the output has the same polarity - and a relay. The diode bridge output, when of a sufficiently high voltage (some 2/3 throttle) switches the relay contacts which allows a direct 24V supply to the fan. The result is a steady DC voltage to the fan, and hence smoke down the pipe, with the model moving forwards or backwards, and fan off at standstill or very slow speeds. The downside is that there is no variation in fan speed with model speed, beyond on or off. It might be possible to 'bleed' enough 24V supply to operate the fan at a slow speed with the relay off (model at standstill), and have full 24V fan speed with the relay on (model running). Just for info, I've taken the fan 24V supply from the smoke heater element supply, which is now manually controlled by a minature toggle switch mounted on the bulkhead and operated from the cockpit, where it is hidden underneath the dash. |
 |
Total elapsed time from the boxes arriving: 9 months
Total model attention time: approx 110 hours (including the test runs & repairs)
Total build time: approx 60 hours
 |
Page
last updated:
|
 |