Drivetrain Design for Boosted's Electric Skateboard
boostedboards.posthaven.com
boostedboards.posthaven.com
Just like a car or motorcycle, right now there's a floor to how cheap it can be and still be great. If that gets lower over time, all the better.
The Kickstarter says 20 mph, 6 mile range, 2000 watts, which gives an energy of 600 watt hours.
A Macbook battery is around 60 watt hours, and weighs about 1.5 pounds; 10 of those would weigh 15 pounds - and take up a ton of space. I don't see the volume of even ONE in any of the photos I've seen.
Where's 600 watt hours of battery hiding?
Eh, walking is probably good for me...
Throwing stuff together and seeing if it works is the essence of engineering.
Properly engineered stuff will work as designed. Imagine an A380 falling out of the sky on the test flight and engineers exchanging betting money based on whether it flew or crashed. "Well, that didn't work.".
Engineering does everything to take the uncertainty out of design as much as possible. It's the anti-thesis of throwing things together to see if they work.
When you are designing the wing for the A380, probably a good idea to bust out the FEA software. But it's still going to be tested with hydraulic rams.
Biggest downside I'm wondering about is only being able to use it when it's dry out (not sure there much to be doe about that while staying reasonable).
I'm a fairly avid cyclist, though. I think than between a boosted board and my trusty bike, I'd cover a pretty huge swath of my use cases.
Really interested in this.
With this at least you could wear boots because you wouldn't have to kick/push/coast.
The motors being used for this project are hobby model aircraft motors. These motors put out a lot of power per unit volume but are most definitely not designed for continuous duty at anywhere near to full output. They are also not sealed against the elements and have bearings selected for reasonably balanced loads with relatively low radial loads.
I have piles of these on my workbench ranging from cheap Chinese units to top of the line German designs. I use these on our planes, helicopters, multi-rotors, boats and cars. At the top end you have amazing hand-crafted quality with a prohibitive price (unless you want to pay $8,000 for a skateboard). At the low end they are cheap and they are junk. I've seen everything from magnets coming off, coils burning out, power leads coming off, bearings going bad prematurely and shafts bending.
In short, while the design process is interesting, I think the most fundamental flaw is being ignored: The motors are not designed, nor are they suitable for, this kind of an application.
What are the safety concerns of something like this? A top speed of 20mph will definitely be unstable for general usage, and even 15 seems more like bicycle territory, where you're seated and have an aerodynamic shape.
We might see many people falling off of these in the future...
The main issue with skateboards is 'speed wobble' vibration in the trucks, but a well set-up board generally isn't prone to this.
The length of the longboard mostly prevents speed wobble which is an uncontrollable side to side swaying which tends to increase in amplitude once it starts.
Secondly, speed wobbles are caused by riders primarily, with gear only impacting it slightly. Put a new rider on a fantastic downhill setup, and they'll probably get speed wobbles, whereas experienced riders can have no trouble riding short, turny board at highspeed. (Look up Maryhill for more info, it's a race where slalom boards are commonly used).
(I'm a snowboarder, and am thinking a lot about getting a longboard for my ~4km commute that I'm currently riding)
There is a slight downhill for the first 300meters or so, then it's basically dead flat. I don't expect to ever be going super-fast or anything on the commute, more like only when I actually go a seek out a steeper hill.
If you panic and lean back, you're effectively only steering with the rear truck, which is not a dynamically-stable situation. Things go wrong very quickly at that point.
And now I think about it, it might not be board flex that limits front-truck turning when leaning back - rather, the lack of weight on the front truck might allow the outside wheel to lift. Either way, it's a bad situation.
Lightweight electric kick scooter could be useful to larger audience as a "last mile" solution.
Edit: Not mine, but these look nice: http://www.goped.com/products/Electric.asp
My current kick scooter weights 12 lbs and i consider it heavy. I can't imagine handling 35 lbs, my bike is lighter :)
[1] http://www.blessthisstuff.com/stuff/living/misc-living/longb...
A go pro video of going from Filbert and Lyon to Filbert and Van Ness, now that would be rock: http://goo.gl/maps/OlHc7
For those that don't live in the city, it's one of the steepest streets in the western hemisphere.
The 11% average over 1km isn't too bad, but the start looks pretty steep. Strava shows it at up to 40%. That's not exactly 100% accurate, but I've ridden 25-30% slopes on Strava and they are hard enough that on my road bike I can't stay seated (the front wheel comes off the ground) and if it is the slightest bit wet the rear wheel slips when you stand.
I'd be very impressed if this can make it up there with a person on it.
But anyways fantastic product, I'll definitely be picking one up at some point.
Any chance you'll sell just the motors...? ;)
And you can buy the motors already! We are using a slightly modified version of a RC airplane motor. Our first prototypes used motors we bought at a local hobby shop.