2023 Jagdpanther new build Part 9

[graham pipe]

A SALUTARY LESSON OR AN EXAMPLE OF ABJECT STUPIDITY...

Hello all and firstly may I wish everyone who reads my scribblings a somewhat belated happy New Year!

My updates have been silent for some time now as we've moved house and I've taken up new employment. However, the JP is still progressing and will be totally finished in the next few months. But just prior to packing up the house and moving the whole shooting match 120 miles further south in France, I was in our large lounge with the JP where I'd just completed some tweaks to the track tension and tidied up the internal wiring.

Figuring a quick test drive around the lounge to be in order, the beast was fired up, driven around the settee then back into the main living space which was about 12 metres in length. All was going well as she rumbled past me kneeling on the floor so, as it neared the large glazed patio doors, I throttled back to a standstill then engaged reverse to neatly park adjacent to our large stone fireplace. Increasing the throttle setting and she suddenly shot backwards seemingly at full throttle and careered into the hearth stonework.

This stopped her in her tracks, so to speak, but the motors were still turning at full throttle and the tracks skidding furiously on the polished tile floor. No response to any input from the transmitter and I had to very quickly scramble over, open the loading hatch and hit the battery kill switch. Major panic ensued from the other settee where wife, dog and 3 cats had been sitting. An out of control tank, Maybach engine sound at max and the television set almost knocked over during its brief flight did assembled company's nerves no good at all!!

But what had caused this disaster? It very quickly became evident when I lifted the roof of the fighting compartment and discovered that I'd forgotten to run the receiver's aerial lead outside of the hull. Therefore, at very close range, she got a signal through the front glacis plate which was still waiting for the mantlet and gun to be installed. But as soon as she was stern on, no signal would penetrate the thick hull and thus it reverted into failsafe mode which should have shut everything down. But it didn't.

Checking my programmable transmitter, I discovered that I'd made a major boo boo. The failsafe function (designed to allow one to select a sequence of events should there be a loss of signal or imminent shutdown owing to very low receiver battery power) had been set to stop the vehicle but I must have been in a hurry or distracted (can the wife be blamed for this? Probably not ...) and thus the failsafe throttle setting had been set to 100% rather than 0%. Oops!!!

I can imagine what many of you will be thinking - what a t**t, not having the aerial wired to the tank's antenna or even trailing over the superstructure. But hey-ho, we live and learn. Thankfully, the tank struck the fireplace at a slight angle and the point of impact was the front towing shackle - just missing the mudguard. So just chipped paint and a chunk knocked out of the hearth surround (glued it back in place with epoxy tinted beige to match the stonework). Phew.

So, a lesson to be learned. Always carry out pre-flight checks and don't operate these vehicles in a confined space as their power is quite incredible.

More to follow as the finishing touches take shape. Now, where's that Valium...

[Gerhard Michel]

Hi Graham,

okay, it's too late for you and your cat, but all my models pass the following little test before running the first time. With the tank on its car jack (for overwintering with free hanging track links) I test all its functions including the fail safe. Thereto I switch off the transmitter at half throttle to see whether the cat stops immediately or not. Additionally I'm using an ESC that stops automatically if its servo signal changes to false data. This can avoid accidents of the tank when the receiver gets damaged and gives me a good feeling of driving safety.

Here the cat entering the jack:



And here the cat on its jack. The tank treads can free run for testing.

[Adrian Harris]

A salutary lesson and glad the damage was minimal.

The failsafe setting on these transmitters are designed for aircraft, so usually put the throttle channel to minimum, which is with the stick at -100%, hence a tank in failsafe takes off backwards at full speed

I'm surprised it was just the aerial being inside the model, as I've run a King Tiger, with the receiver sitting inside the hull, a couple of hundred meters away and only been told by the transmitter that the signal was low, not critical.

Adrian

[Marco Peter]

I haven't run the receiver antenna outside a hull since I quit using 27mhz I think? Ages ago.

What system was yours using Graham?

[graham pipe]

Hi Marco.
I'm using a 35 Mhz JR X388 system. Old skool now but always worked fine when I flew ducted fan and turbine powered jets back in the 1990's.

[graham pipe]

Hi Marco.
I'm using a 35 Mhz JR X388 system. Old skool now but always worked fine when I flew ducted fan and turbine powered jets back in the 1990's.

[Gerhard Michel]

Hi all,

well, all the RC systems I know have two kinds of failsafe, HOLD and POS. HOLD means that all active servo positions are frozen when failsafe starts; POS means that all servos run into the position the user has specified at initiation of failsafe when programming the TX. Contrary to airplane usage our transmitters (hopefully) have a self-centered throttle position; therefore we can use the POS failsafe for all our functions.


Hi Graham,

at least in Germany it is forbidden to use 35 MHz systems for other models than airplanes. Another reason to avoid that is that MHz systems are much more sensitive against radio interferences caused by electric motors. An 1/6 scale model with 100 kgs and more is not a toy and can cause some damage when coming out of control; so I would only use a most suitable RC system (GHz) to avoid damages at persons and material.