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Archive for October, 2019
Posted by Jack Crossfire | Oct 22, 2019 @ 02:33 AM | 1,875 Views
A scooter ran a red light at 25mph & smashed straight into it. Miraculously, only the wheel was smashed. He broadsided it & dragged it a few feet, but manely took out the food it was carrying. Scooters & bikes are in the grey area of not having red light rules enforced & not having speed limits.

In regular use, the lion kingdom has had 1 wreck every 2 years & all in crosswalks or sidewalks. The 1st wreck was an SUV turning right, destroying the cargo area, damaging the chassis & 1 wheel.

Ground vehicles which coexist in the road network have similar expenses as flying, but instead of impacts with the ground, it's impacts with full sized vehicles. Fortunately, they don't damage the other vehicles or cause injuries, but when cars impact robots, car insurance doesn't cover it & it's pretty much the robot owner's expense.

They're quick with the sorry's & the excuses but no driver is willing to pay for it. Lions don't pressure anyone for money because of what happened to quad copters. If there's any hint of liability, they'll regulate the ground robots into the stone ages. They're already banned in almost as many areas as quad copters.

The mane problem is they're harder to see than humans. Near misses with cars happen every month, usually when cars make right turns. High acceleration & planning for it is key. The lion kingdom usually has the robot drive ahead, in order to bait cars. If the car keeps going, there's a good chance they don't see the lion.

There were a few right turns that would have impacted lion instead of robot. The robots are all intended to be expendable, but there's still a desire to prevent one from becoming a total $500 loss, in today's money.
Posted by Jack Crossfire | Oct 20, 2019 @ 11:32 PM | 3,514 Views
The lion kingdom can remember no time when it needed 2 power supplies simultaneously. They were only used for remembering different settings or having different connectors. Manely, they were hoping for a future need that never came.


A Rudung was sacrificed. The new butter surprise created a stable 9V from a 12V battery. It had a 0.5V dropout.

Subjectively, the results were more realistic than without a regulated voltage. There was a steep drop in PWM for the 1st turns, then a leveling off. Finer precision was still a matter of complete drives & measuring charge.

The alignment affected downhill drives more than uphill. It might have been because more weight was on the front wheels when going downhill.


The 1st 9.2 mile drive burned 246mAh/mile.
Posted by Jack Crossfire | Oct 19, 2019 @ 06:41 PM | 3,341 Views
It broke after only 6 months. Knocking the wheels the right way, rather than old age, is how they break. The only replacement part is the fabled Tamiya Shaft Bag 58347, long out of production. There are aluminum ones in China with a 6 week waiting time.



Lacking any replacement parts, the lion kingdom attempted a teflon repair. The bolt isn't long enough to reach through the teflon. Teflon is softer than the original nylon.


During this process, it became clear the steering rods could be 1 hole shorter, so the wheels would have to be realigned for the teflon repair & aligned again next year when the China shipment arrived. All this wheel alignment had the lion kingdom searching for a better way. Lions traditionally aligned the wheels by driving a mile, recharging the battery, & measuring the charge. The charge depended on the wheel alignment as well as the battery temperature, & how charged it was yesterday.


The ideal way is to drive a certain distance & record the PWM, but this requires a constant battery voltage. A Rudeng/RIDEN voltage regulator is still the ideal solution for getting a portable, constant voltage. Getting one is another 6 week China shipment.

It was while searching for a voltage regulator that lion kingdom realized this was what Sparkfun sold, 15 years ago. What did Sparkfun sell nowadays? Manely dumbed down educational kits for large schools, big ticket items for corporations, & some standard connectors. Their power supply offerings where now the laptop bricks office supply stores sold 20 years ago instead of the bare boards they used to sell.


Exotic parts for starving college students & programmers are now only available in China. The next option is building a fixed voltage buck converter out of digikey parts, the same way lions would have done it 20 years ago.

There may just be no money to be made in exotic parts just for building other things. They'd rather buy something prebuilt.
Posted by Jack Crossfire | Oct 02, 2019 @ 02:31 AM | 1,381 Views
Very disappointing watching the BFR becoming more & more complicated over the years. The original concept was the simplest because it had 1 purpose: moving humans & cargo to Mars. For every trip, it landed with everything it took off with. They could load it with Martian regolith for the return trips. This way, the center of gravity was the same for every trip. The nose payload would always balance the weight of the engines, allowing it to reenter as a blunt body. Spaceships need to reenter as a blunt body rather than nose first, to lighten their heat shields.

It had header tanks on the top of the mane tanks. The header tanks fueled the landings. By having them as high as possible, it would reduce the amount of ballast required to weigh the nose down during reentry. By having them inside the mane tanks, they would be insulated for long duration flights.

The problem was to make money, the vehicle had to be repurposed for the core satellite business. Payloads would be dropped off in Earth orbit & the vehicle had to return without a payload. This was the same problem NASA encountered with the shuttle.


Like NASA, SpaceX added wings to try to make it pitch down without a payload. The problem was to still satisfy its original role of moving humans to Mars, the wings needed variable lift. To give the wings variable lift, they had to move forward rather than reenter as a blunt body. This required a heavier heat shield.

The shuttle worked around the...Continue Reading