Hotrod parts. Racing?

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Hotrod parts. Racing?

Postby slomobile » 23 Nov 2021, 20:27

:twisted: For building a Gonzo, really fast, powerful outdoor chair from scratch, what are your favourite "Hot Rod" parts?
If wheelchair races were a thing, what would you use. Wait, are wheelchair races a thing?

Not batteries, they get plenty of coverage, all the other parts needed to use big C batteries.
Not necessarily intended for wheelchair parts. Looking for non-medical joystick, joystick alternatives, controllers, motors, suspension, steering aids(including software/firmware). Maybe AC induction motors, or SepEx motors. Are there any SynRM motors at the right scale?
Links to reliable storefronts welcome.
I've heard requests for 48v systems. What controllers and motors would you like to use?

Here are some links I have, what else is there?
https://ampflow.com/controllers/
https://www.dimensionengineering.com/pr ... rtooth2x60
https://www.mpja.com/X-Y-Z-Axis-Motion- ... /34791+MI/
https://newsite.ctr-electronics.com/her ... ent-board/
https://www.electrocraft.com/motors-for ... /mobility/
https://www.simplefoc.com/
https://www.vexrobotics.com/pro
https://plumquick.com/

I tried putting a u in favourite for you Brits. Feels fancy.
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Re: Hotrod parts. Racing?

Postby Burgerman » 23 Nov 2021, 21:08

45v lithium. Stock 8mph motors. 16 mph. 150A per channel roboteq controller and a script that took 3 years to develop to make it properly controllable, custom control script by lenny, current sensors, 32 mosfets to handle the current needed, and its as fast as any sane person would go.

https://www.wheelchairdriver.com/BM-MK3 ... rchair.htm



VID...
Uphill. Causes caster shake. Look carefully at front casters. https://www.wheelchairdriver.com/BM3-co ... -shake.mp4
Never shakes of the flat or on the main roads. Where I really can overtake cars.
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Re: Hotrod parts. Racing?

Postby fishinjunky » 27 Nov 2021, 14:31

Burgerman wrote:45v lithium. Stock 8mph motors. 16 mph. 150A per channel roboteq controller and a script that took 3 years to develop to make it properly controllable, custom control script by lenny, current sensors, 32 mosfets to handle the current needed, and its as fast as any sane person would go.

https://www.wheelchairdriver.com/BM-MK3 ... rchair.htm



VID...
Uphill. Causes caster shake. Look carefully at front casters. https://www.wheelchairdriver.com/BM3-co ... -shake.mp4
Never shakes of the flat or on the main roads. Where I really can overtake cars.


that would be my dream chair but designed with tilt and recline.
Invacare tdx sp
Bounder 300M
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Re: Hotrod parts. Racing?

Postby slomobile » 27 Nov 2021, 18:15

When floating the idea of powerchair racing elsewhere, it was suggested that a pulling contest, like truck or tractor pulling but with chairs might be fun.
They say production car technology improves due to racing. Maybe chair technology could as well.
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Re: Hotrod parts. Racing?

Postby Burgerman » 27 Nov 2021, 19:56

Similar story.

One of the bike magazines held a yearly drag race for street bikes. To see who had the fastest street bike. I did very well on year 1. Since I was running a STREET bike, with 1150cc and 140bghp of nitrous oxide on top.

Year 2 all the top competitors had drag bikes that had no cooling systems, no charging systems, no on board starter, no lights just air brushed on, tyres that were stretched out on to wider rims and lowered till almost no ground clearance. And long swing arms that wouldnt work on the road. And air shifters, turbos, nitrous, C14 fuel, and no rear suspension. They "looked" a bit like street bikes. They were all out drag bikes and completely unusable on the public highway. So I came about last!

What I am saying is that I can easily build a thing I call a wheelchair that will pull a barn down. Long, low, super heavy, super low gearing, etc. And now its no longer a wheelchair.
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Re: Hotrod parts. Racing?

Postby ex-Gooserider » 04 Dec 2021, 05:20

Back in my Biker days, our state's rights organization, the MMA, (In my day it was the Modified Motorcycle Association, the name has since changed to "Mass. Motorcycle Assoc.") used to do a bike show, but we had a bit of a twist, in that we required all entries in the judged classes that were got prices to have a current valid registration and inspection sticker, and be RIDDEN to the event... Any "Trailer Queens" got put in an exhibition class that had no prizes or judging (They still paid the full entry fee)

It wasn't a perfect solution, but was at least a step in the direction of "keeping em honest"

I would have thought that if the bike magazine wanted to do the same sort of keeping it to 'real' street bikes, they could have done the same rules, and possibly added a requirement to participate in a group ride of some reasonable distance (50 miles?) on a variety of public roads....

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Quickie Q-7
Invacare Mariner
Want to make / get a better chair, ideally one that stands.
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Re: Hotrod parts. Racing?

Postby slomobile » 01 Jan 2022, 22:33

Regarding how competition pushes vehicles to the extreme, that is kind of the point. To see how far the rules can be pushed before creating a new category. The F1 elf 6 wheeler, fan cars, floating ground effects skirts, Group B rally. Yes, they were eventually excluded from competition, but what the world learned about engineering from these experiments has value beyond any trophy. So what if it gets a bit silly, it is a means of self expression.

My boy was in 2 different parades this year so I had a chance to roll up and down the staging areas getting a close look at the mobile creations people made. A group called Bluez Kreuzers or some similarly odd spelling has built overstuffed easy chairs on top of powerchair bases which they use like neighborhood golf carts. One had a small side table attached and the leg lamp from a Chrismas Story, major award. Another had a full luxury nail salon spa chair including the working massager and footbath. A different float had a manual chair with towbar looking like a 2 wheel horse carriage. A Hillbilly group built an outhouse on a powerchair base. The more ablebodied people that find a use for our old chairs, the more people we can find to fix them when in need.

I've got 4 matched single stage worm gear motors without brakes that I would like to experiment with. Any bets on what happens when I put 13" wheels on one end and 25" car wheels on the other?
I'm pretty sure it will have less torque than if all wheels were 13" and less top speed than if all were 25". But I'm not sure what happens after the 13" ers get us going and the 25"ers start to hit their stride and push the 13"s faster than normal top speed turning them into generators. Can R-net 120 survive that?
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Re: Hotrod parts. Racing?

Postby Burgerman » 02 Jan 2022, 04:01

Its the opposite way around. As you begin to roll the large wheel motors will suck up the most alms, reducing any torque the small wheel ones woud have provided and acceleration will be worse than ever. And as the speed increases then you will not get past the speed of the small wheel motors as they will generate lots of drag and suck up any extra speed the large wheels try to give. Because theres losses in the motors generating and losses in the ones still pushing. All you will generate is extra heat.

The r-net will be fine. And it will not see anything abnormal.
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Re: Hotrod parts. Racing?

Postby slomobile » 04 Jan 2022, 01:51

Lets see if I got a rough starting point.
2 of these motors and 13" wheels are supposed to reach 6mph by themselves.
6mph= 6336 inches/minute
6336/(Pi*13) = 155RPM top speed
(PI*25)*155 = 12175 inches/minute
top (theoretical) big wheel speed is about double actual small wheel speed.
The first 80% of throttle movement will be scaled 5-100% PWM duty for the small wheels and 5-50% PWM duty for the big wheels.
The last 20% of throttle will have small wheels at 100% constant so they drag as little as possible. Big wheels scaled from 50-100% to hopefully push it a bit over 6.
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Re: Hotrod parts. Racing?

Postby Burgerman » 04 Jan 2022, 10:06

You are using 2 controllers? Then yes.

The controller that is scaled will just suck up almost double the current at any given load and have half the torque. And waste crap loads of power. Why would you want that?

As they say in the EV forums - volt up, gear down.
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Re: Hotrod parts. Racing?

Postby slomobile » 04 Jan 2022, 22:23

Why would you want that?

To go a bit faster, to provide at least a little drive from every wheel for traction on wet grass, flotation, to have the front wheels quite large for broaching obstacles. for hand pushing, and for fitting a drive disconnect inside the large wheels so it can be towed. For seeing and understanding the effect in real life vs theory. And because I already have them.

Can you think of a better algorithm for scaling the controllers?
The idea was that while the small wheels are still being throttled, the large wheels are only provided enough on time to overcome their own rolling resistance plus a small constant traction for consistent steering feel.
Maybe the small wheels should be voltage proportional to throttle and large wheels current proportional to throttle.
The last inefficient 20% is only used if you are stuck, or need the most speed the thing can do.

This thing would be for outdoors only and accommodate my prone driving position, making it large enough to carry whatever amount of batteries I need for range.
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Re: Hotrod parts. Racing?

Postby Burgerman » 04 Jan 2022, 23:27

But the most efficient way to go a little faster would be to use slightly taller gearing matched on all motors. And again using 2 motors only is more efficient than 4. If you must have larger front wheels match the gearing to the wheel so both sets achieve your desired top speed at 100% pulsewidth.
Since when if different producing no thrust forwards or running at constant speed unloaded they all take around 5 to 8 amps regardless.

The only sensible way to get more speed that doesent either waste power, or lose torque, orgenerate more heat is either a voltage increase (as in my BM3 chair for that reason) or a reduction in impedance. But at the low voltages we use already that is down to around 30mOhm for the best 4 pole motors. Thats around the same impedance as the wiring or controller so going even lower is just going to waste more as heat.
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