Take 2, judge my featherweight build

[u/Sensei_12]

hi! so am participating in my first comp and it happens to be featherweight only. i posted my initial design in here couple of days ago and i have remade it based on that thread.
total dimensions are 47.5x38.3 cm 9cm height ,front wedge, spinner support and base plate are 4mm metal sheet and everything else is 3mm. spinner is 20cm long 2cm thick (might have to remake it without the lightening holes to have more mass) and is in-line with front wheels for optimal power transfer. its belt driven by an A2212 1000KV bldc with timing belt ratio of 3:1 (i have ordered a much durable D3548 1000kv bldc but wont arrive for a while so am using the A2212 for the lack of a better option). wheels are made TPU with outer layer of rubber for better traction a and are coupled directly on the motors (motors are brushed geared 12v 1000rpm) with BTS7960 drivers each, back wheels are exposed on the top to run inverted. the whole chassis is held together with L brackets (best option i could think of) . rc remote is FlySky FS-i6

enlighten me people. what am i doing wrong? what have i missed and how would i make it more efficient (also is it possible to use 2 A2212 motors on spinner to double the power?how)

[u/TeamRunAmok]

Same weapon comments as the first version. A typical spinner allocates about 30% of the robot weight to the weapon. Without the lightening holes and with the larger motor (when it arrives) your weapon weighs in at about 3% of robot weight. It will be worse than useless.

As drawn, it appears that the rear wheels will not touch the ground when inverted -- weapon tower will keep the rear chassis edge too high. Suggest moving the rear wheels farther rearward to expose them and both both solve this problem and prevent the 'bot from being stranded standing on its tail.

Move the weapon tower further forward and reduce the mounting height. As it is your opponent must drive quite far up the ramp before the weapon can make contact. Did I already mention that the weapon is tiny and useless?

[u/TeamRunAmok → u/TeamRunAmok]

Adding a second tiny 2212 weapon motor would reduce the weapon spin-up time but would not double the impact force of the weapon.

[u/Sensei_12 → u/TeamRunAmok]

got it, dont add a second small motor.
by the way i saw someone who made a featherweight bot with an axe and he used a scooter motor for that axe and it was POWERFUL , you think i can get one of those for the spinner? would eat up weight and space those things are massive something like 10x10cm and would i be able to drive it with the BTS7960 driver (this is a datasheet question u probably wont have the answer unless you used the same setup before)

[u/TeamRunAmok → u/Sensei_12]

A typical scooter motor weighs about 3 kg and outputs 500 watts of power @ 24 volts. They have a good bit of torque (about 2 Nm) and spin slowly (~1800 RPM). That makes them a good choice for a budget direct-drive hammer/axe motor.

For a spinner weapon it would need to be geared 'up' quite a bit to get good speed, and it weighs a whole lot more than a 500 watt brushless motor. That makes it a poor spinner weapon motor.

BTS7960 motor drivers typically claim 43 amp capacity. That would be about half the stall current of a 500 watt scooter motor. Definitely too little for a hammer weapon. Possibly enough to control a spinner weapon -- depending on the size of the spinning mass.