King Tiger

[Jerry Carducci]

I just opened the options box for my King Tiger. I'd purchased the parts in early 2020, the kit from Armortek a little earlier.

My word those are heavy motors!

How many different size motors has Armortek used over the years? I'm sure these are different; bigger, heavier than those in
my Sd.Kfz. 7 and M3 Lee.... It would make sense that they're bigger but when I picked up the box from the pile o' kits it was a lot
heavier than I recalled.

So begins my King Tiger construction project...

Jerry

[Mark Allen]

The fun begins!

If I could offer any insight from mine, it would be: Check the hull sides and rear plate for warp-age. They have to be dead on or all sorts of issues can raise their head pages later in the manual. Particularly critical is the fit of the the lower hull sides to the rear plate. Any silliness there and you could run into problems getting the track tensioners aligned and operating smoothly.

Mark

[Jerry Carducci]

Performed a brief run test of the KT motors. Impressive things the are. About 12-15 volts max.

Motor test run

I didn't have an ammeter in line with this test but I'll do that later to see if under a no load test that they're drawing about the
same power as it speaks to whether the tank will be able to run straight on its own, all else being equal.

Already I can tell that one of these needs further investigation, see if you hear what I hear. Warranties aside I'm not certain
what I can affect or live with.

Jerry

[Mark Allen]

The second motor appears to have a bent output shaft. Its rotation correlates to the change in pitch I hear.

Mark

[Jerry Carducci]

I went ahead and took that motor apart. This is not a new issue for me as my parents told me the first thing I did with my toys as a wee lad was to take them apart to see the guts. I've gotten better since than at putting things back together.

Yes I know the warranty went out the window, okay I got that.

During my disassembly I noticed that the pin hole for the pinion and the shaft are not well aligned. The rolled pin was forced in to the point where it
was bent like a banana. Hmmm.

What I found was somewhat surprising. I disassembled it as far as I dared and try as I might I could not remove the outer (M 1.5??) pinion gear
from the shaft. It is 'ON THERE' for keeps. I tried a gear puller to no avail and was going to use my 20 ton hydraulic press before I stopped myself
from doing damage. I decided I will live with this thing as is for now.

I was able to remove the bevel gear from the shaft ; this appears to be a hypoid helical bevel gear but I may be wrong. Carefully putting this precious gear and key aside I decided to mount the shaft with remaining flange and the resistant pinion gear in my lathe where I could use a dial indicator. I held in by the greater diameter section where the bevel gear mounts and set the dial indicator first at the shaft just before the pinion and then on the pinion's flange avoiding the pin hole. To my surprise and pleasure I found the run-out to actually be minimal, no more than +/- .003" which I can live with.

So why the run-out when assembled? I noticed that the output shat is supposed to ride in a large ball bearing however this is a very loose fit,
almost sloppy. I believe here is where the deviation from running true comes from. As a test I held the motor fixed, then ran it while pressing against the shaft with a thick piece of aluminium. The run-out lessened noticeably.

So long story short is I don't like things to not run true but assuming it doesn't not affect running I will live with this. Should it ever fail I will make
a new shaft and replace whatever gear need replacing hoping that pretty helical gear is not one of them!

Onward!

Jerry

[John Clarke]

Hi Jerry, nice honest review.
I Remember when I did a graphic strip down on the Chieftains Gearboxes back in 2020, a few surprises and made a few mods.
Tolerance's are tight now.
Your the expert now.
Are you going to make a motor cradle for the heavy lumps or just let em hang?

[Jerry Carducci]

Hi Jerry, nice honest review.
I Remember when I did a graphic strip down on the Chieftains Gearboxes back in 2020, a few surprises and made a few mods.
Tolerance's are tight now.
Your the expert now.
Are you going to make a motor cradle for the heavy lumps or just let em hang?

Y'know I've thought about designing a motor cradle and casting one in aluminium; I'd considered that when I built my Lee. That is
an awful lot of weight to be hanging around on those, what?, 4 bolts? Perhaps I might do that this time. Perhaps I could design cooling fins as part of
it? Perhaps if I had a large enough 3D printer I could make one that way.

I hope every knows I wasn't trying to disparage the motors or their construction. As I mentioned to someone else I first began in this hobby
building, maintaining and running glow powered 1/10 scale models. With engines running at 10-12k rpm any out of true conditions could cause
destructive vibrations and such assemblies wouldn't stay assembled long. So I've always been concerned to keep things running as true as I'm able.
Internal speeds here aren't anywhere as great and even though accuracy seldom is a bad thing I probably have more latitude here. I which I had a spare motor to experiment with; I'd like the ability to experiment. I'd buy one if I could.

Jerry

[John Clarke]

I was mightily impressed that so much torque could be developed from the Amortek gearboxes. Some may want top end scale speeds but top end scale speeds come with consequences and not just to the gearbox.

The gearboxes are unique as far as I know, only off the shelf at Armortek, a big shelf hopefully, so I think it's a good idea to give them the respect they deserve. If Chieftain ever gets off the wooden blocks, I know I've given "them there" gearboxes the best opertunitity to serve the model well.

3 set screws support the motor gear box on the Chieftain Jerry, that's
why I thought I give them a little support with the cradle.

[Jerry Carducci]

I spent some time sorting the motor situation and I'm satisfied with .0005" run out on both as it stands so I'm moving on to
trials and testing with the electronics.

I wanted to use my FrSky X20HD Tandem system; one of several that uses the proprietary ETHOS OS. Some say that ETHOS
is easier to work with that OpenTx but I believe that's based solely on interfacing with the OS via the transmitter controls
themslves. The X18, X20 and XE series systems have fairly large touch screens and the GUI is miles ahead of the GUI presented
by a Taranis X9D running OpenTx for example. OpenTx development I understand is frozen and new developments are being done
on the successor OS EdgeTx. ETHOS seems like it will be around a while and I read that some of the lead developers from the original
OpenTx were involved with ETHOS as well.

As for easier to use? I used OpenTx Companion nearly exclusively to develop model profiles; using a full sized keyboard, mouse and large screen
is hard to beat. I find that ETHOS IS way easier to use via the transmitter however I will be truly pleased if /when ETHOS Suite, the PC application used for ETHOS firmware maintenance also implements a model profile edit feature. The feature has a button however it is just a stub. My hands are
clumsy so using the touch screen interface takes a determined effort on my part but it does work well.

The first thing I wanted to do is define a mix using channels 3 and 4, I like the left stick in Mode II configuration to control forward/reverse and steering.
I was easily able to create this mix, rather two mixes to get this control in and tested. I'm using a FrSky TDR10 receiver that supports more than enough
channels for this project.

Telemetry. I love gadgets. I have, on the one smart port three sensors daisy chained, a current sensor, a voltage sensor and for no other reason than I could: a GPS unit! As I said I love gadgets. I'm next going to try my hand at defining additional views to display the Telemetry data.
When all the rest is done and tested to my satisfaction I'm going to attempt to use the feature that prompted me to get this particular radio: the ability to receive a real time FPV stream and display it on the main LCD display. The plan is to use a HDZero "Whoop Lite" FPV transmitter for which the FrsSky is compatible. There's another interface that's supposed to transmit selected telemetry data along with the video stream but that I'll hold off on until the very last. The CCD camera is absolutely tiny, smaller than the head of most 1/6 figures and I'm not sure where I'll mount it...

So. It's going to be fun!

Jerry

[Jerry Carducci]

I neglected to mention that discovery of the smart port sensors is as easy as I've ever experienced.

I've included a preliminary screenshot of a secondary screen I defined using various inputs to populate the widgets, GPS( or course!),
voltage for main (LiPo), Current and main system (Xmitter) voltage. I used another LiPo pack for the input as I haven't decided where I'll put the inductor to read the current. I'd previously 'Jerry' rigged (I believe I'm allowed to say that) a temporary connection just so I could see it work with the actual battery but as it's pretty much a permanent installation when it's done and I don't really know yet where I'm going to place it in the model... I use a stand-in battery to see some movement.

You can't possibly see the GPS map but it's one I used a tool (https://ethosmap.hobby4life.nl/) to create a local map of my area. I'm going to remake this map to be a bit closer detail and recheck the GPS coordinates they provide, but it does work and it's fun to see! Totally useless really but the gadget appeal is worth it... At some point I have to try designing my own lua script to be invoked via a switch to tell the model to come back home to it's starting point. I can't see why I won't be able to persist the originating GPS coordinates for the duration of a run. I moved the system around my backyard prior to building this graphic widget and cross checked the longitude and latitude values with a handheld GPS and they're exact. The map and script is cute but as I said pretty impractical.

So on to FPV.

Ain't technology grand!

Jerry

[Mark Allen]

It really is fun fooling with the tech isn't it? Im doing the FPV in my KT too. I'm using a stand alone 5.8Ghrz programable transmitter (power level and channel). I located an antenna to go on the rear deck that "resembles" the original antenna used there on the command versions. Also in the video system is a three way switcher with video stabilization, one three way switch on the Xmitter selects camera channel. Then three cameras; one in the drivers periscope, one hidden somewhere on rear plate (probably in the jack block and the final one in the commander figure. The periscope has been made to rotate via servo. It is range limited and slew rate limited by the programming in the Xmitter , all in all a believable looking operation. The turret of course rotates the commander, but the commander himself is getting animated for rotation of head and torso. With the three cameras and the rotations I can see anywhere. The display is a 7" Black Pearl monitor mounted to the X9D transmitter.

I have tested the video system components and also as a system including the periscope. I have a small noise issue in all all three feeds which I will need to investigate. I suspect the unshielded video wire from the camera to the switcher.

[Jerry Carducci]

I performed an initial test of the fpv system I wish to use with this build. That the components were most originally intended for
aircraft the components are comparatively tiny as may be seen in the photo.

The components used are an HDZero 'Whoop Lite' VTX - the video transmitter, a HDZero Camera and a TBRC OSD ( V1) -on screen display, that
powers the VTX and will also send embedded telemetry data (in the video stream) of it's own regarding the main battery. A plus
is the OSD is capable of running directly off of the 24 volt main battery as an in-line component.

For the test I propped up the components on a stool at the end of my yard and simply used a rather tired Lipo 7,4 volt pack to power the OSD which is at the bottom of the range it requires. It can use up to a 8S pack (28-29volts?) but delivers the required voltage to the VTX which is 10v. I would have used my large LiFePo4 packs but I need to make a adapter cord.

I'm quite pleased with the video quality, remains to be seen how the 5,4ghz stream will work from a heavy metal model. I don't plan on embedding
this system permanently in any model. It's small, light yet gets quite warm in use so I think some implementation partially exposed should work. Haven't finally decided.

Except for having to do some annoyingly twitchy mini-soldering onto the VTX board ( the solder just didn't want to wet the solder pads!) to provide a communication line from VTX to OSD the setup compreised of

1)powering up the X20HD transmitter and switching to DISP mode
2) powering up the fpv system.

The video stream displayed immediately- I didn't need to hunt for the correct video channel.

I think I can start building now...!

Jerry

[Jerry Carducci]

I wanted to fiddle with the sound selection. Never been a fan of the toggle switches- just a foible of mine. Wanted to use a Pot+ switch mix as I've
done with Benedini boards using open TX . This fellow explains it more patiently than I could (https://radindustries.wordpress.com/202 ... -tutorial/). Ultimately I chose not to follow this path as it was becoming too fiddly here.

I thank Adrian for the suggestion of using push button switches located on the rear of the transmitter; the X20 series has these as well. Once I set this up it was clear that it's the way to go so there it is. Last impasse to actually turning screws, nuts and sweating away in the oven than is my shop is in the rear view mirror....

Jerry

[Jerry Carducci]

Preparing to assemble the lower hull. Identified some unusual characteristics of the rear hull plate and brought
it to the attention of Armortek. In the meantime reviewing assembly to determine how I want to approach this.
If I want to apply any modifications

Deciding if I want to make or have made steel sprocket rings though I would prefer the latter if steel is the way to go.

Jerry

[Jerry Carducci]

Trial fitting lower hull components. Already this beast grows heavy. I knew I shouldn't have given up weight lifting early. At university I did
mix a weigh lifting course in among my chemistry major course work - I was able to deadlift 350 pounds at one point....

That was ages ago and surely doesn't help me now...

Onward!

Jerry