350KG RC TANK - PROGRAM : CHAROGNARD

Project Logs

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ENGINE
RC ORDNANCE • 11/15/2020 at 10:31 • 0 comments

FULL TRHOTTLE !
I wanted to use an IC engine as main power source from the very begining.
I chose a 196cc 4 800W (6.5hp) 4 stroke engine. It includes both manual and electric start. The engine is equipped with a centrifugal clutch, which simplifies my work a lot. It is a "LIFAN 168F-2D-B" engine.
VIDEO
Servos were quite easy to add and worked very well right away. 3kg.cm torque proves to be enough.
closest servo : choke
other servo : throttle
The engine will be fixed on 4 anti vibration mounts. I also had to add a couple profils to stiffen the base plate, so that it doesn't bend under engine's torque.
TO BE CONTINUED....
SUSPENSION
RC ORDNANCE • 11/14/2020 at 21:36 • 0 comments

ON THE BOUNCE !

I will be using the torsion bar concept : This is a very compact and low maintainance suspension system.

I wil try to make an adjustable system, since I don't know the exact weight of the finished tank. It can also be useful to modify the initial strain to change the suspension behaviour if needed.

The locking assembly will allow to modify the initial strain of the suspension
A lot of holes to drill again...
... and to tap !
11 more to go !
The suspension blocks will be screwed to their mounts...
... and the mounts welde to the bottom plate
I also welded U shaped profils to prevent the plate to bend too much under the torsion strain
well, welding DOES induce strains from heating...
1300MP high strengh spring steel will be used for the torsion bars
The torsion bar pivots inside bushings
GEARBOX, Mk2
RC ORDNANCE • 11/14/2020 at 20:36 • 0 comments

SWITCHING GEAR...

(continued from log "Gearbox Mk1")

Since I was going to face major problems with the Mk1 gearbox, I anticipated the construction of Mk2, featuring :

-Sprocket tensioners

-Full metal shifting forks

-Additional shaft, allowing to dismount the gearbox more easily.

It features 4 reversible gears.

There are no synchronizers, jus basic dog clutches. The dog clutches are motioned by 9kg RC servos, from an arduino.

It is a semi-automated gearbox : when pushing "shift up" or "shift down", the algorithm does all the necessary steps to change gear.

It is a semi-intelligent gearbox that detects when errors occure (e.g. blocked mechanism) and acts accordingly.

The first trial turned to be pretty succesful and quite promissing :

From CAD....

... to reality

Tensioners

New metal forks

Switch detecting dog clutch position

Cfqdfdqfgf
Arduino + radio module

CONCLUSION

The concept proves working pretty well (including at high speed) without load.
We'll have to test it again with the rest of the transmission, (double differential + steering system) ; under load once the chassis is done ; and under full load once the turret is complete...
RADIO
RC ORDNANCE • 05/17/2020 at 07:52 • 0 comments

ALL WE HEAR IS RADIO GAGA

Since I didnt really learn electronics at school, I expectef the radio to be quite difficult to build. but it turned out easier than I thought, it's just a basic button box, with an Adruino, a screen, a 2.4GHz module and a battery of course. The box is 3D printed (SLA) and the pannel is made out of wod, laser cut.

HOMEMADE BRIDGE DIVIDER
CHASSIS FRAME
RC ORDNANCE • 05/16/2020 at 19:18 • 0 comments

GETTING THE RIGHT FRAME OF MIND

SUMMARY

Building the frame wasn't that hard, but much, much longer than I expected. I had to drill several hundreds of holes. I also had to be very patient and very cautious with positioning and maintaining the profils while welding. Since I am no professional welder, I had to improve some weldings after the polishing step revealed weaknesses. The most difficult part was to cut and weld the angled profiles properly.

From CAD...

... to reality
CONSTRUCTION
At first I made the frame in 2 parts : top and bottom

And it was a bad idea :

MUCH BETTER !

profil welding. I also Riveted a lot of nuts for potential mountings interfaces

The bottom plate will be fixed to the chassis by these nuts

Here we see the plate's nut inside the frame's hole

welding of the screws for engine mounts

Bottom plate

Core of the frame assembled with gearbox Mk1, and engine... So far so good!

Still got a lot of work...

These front sections were very long to cut and assemble, because of the tricky angles

Front view

Then i welded the left and right wings + turret mounting + rear section :

the pallets are 1m20*0.8m

After a few improvements on the fly, the frame is now complete. I then added a rust protection coating on every single surfaces. Just like real tanks, this one will have a long, and rough life. Let's protect it from the start.

Upside down view
GEARBOX, Mk1
RC ORDNANCE • 05/16/2020 at 17:20 • 0 comments

FULL SPEED AHEAD !

The gearbox design has been quite a challenge : I have a lot of mechanical power to transmit (4.8kW) with a high speed on one side and high torque on the other. Not to mention that the gearbox had to be as compact as possible to fit in the tank. I used roller chains instead of gears to make it easier to assemble run and maintain, as is it my first gearbox project.

CAD

MATH TIME

OUTCOME

The Mk1 Gearbox has never been tested. I figured I would obviously run to dangerous problems without tensioner sprockets. It would also to be difficult in maintainance to disconnect the gearbox output from the rest of transmission.
See you at the "Gearbox Mk2" post ;) !!
EARLY DESIGNS
RC ORDNANCE • 05/16/2020 at 17:06 • 0 comments

Because history matters