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Old 08-21-2017, 04:26 AM   #31 (permalink)
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Originally Posted by The Toecutter View Post
I have sort of figured this project wouldn't be completed until at least the 3rd body.
I would change that to "3rd body and chassis." In automobiles, just doubling the power usually is as much as one chassis can be modified to take gracefully. The electrics have the best chance of staying suitable, but they are evolving quickly and that could also change your mind, as might the performance numbers on #2. With my body weight added, I'd have about 40 lbs/hp, so I wouldn't out-accelerate many cars, unless your motor is just rated at constant duty and the controller can heat it up.

Have you compared estimates between fairing the wheels separately vs installing a 40" door? Some houses are much improved by double doors, too.


Last edited by Bicycle Bob; 08-21-2017 at 05:11 AM.. Reason: More stuff
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Old 08-21-2017, 05:50 PM   #32 (permalink)
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Make the head fairing detachable? The book by Katz I purchased on Amazon; there is a 2nd ed.
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Old 08-21-2017, 07:56 PM   #33 (permalink)
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With my body weight added, I'd have about 40 lbs/hp, so I wouldn't out-accelerate many cars, unless your motor is just rated at constant duty and the controller can heat it up.
It's not just power to weight ratio that matters, but torque. The Leafbike hub motor that I plan to use can make car-like torque without destroying itself, in a vehicle whose laden weight is 1/10th that of a car. In order to get this thing to take on cars at lower speeds, the traction of my rear tire will be the limiting factor, and I do not yet know precisely how much traction it has. It's a Schwalbe Marathon Plus, and if I pedal with full strength at a stop in 1st gear in either the 28T or 38T rings, I can make the back tire break traction without a motor. So its traction isn't all that great if it can't even handle human power, let alone human power coupled with an electric motor.

I ran a simulation of this hypothetical vehicle fitted with a 1500W continuous Leafmotor with the 5T wind at 72Vmax, 6 kW, 83A, 120A phase current, 30/40/60T front chainring, 42-11T in the rear, and the rider pedaling with 500W going through the rear gears up to top speed. At a 0.25 Cd, 6 sq ft frontal area, 300 lbs laden weight, 0.008 Crr, 26” wheel, controller voltage/current limiting factors(assume for this calculation a battery powerful enough to run this with minimal sag and that traction won't be an issue), and the rider starting out in a 60T front and 28T rear gear, no traction limit accounted for, I get the following performance:

0-10 mph: 0.8 seconds

0-20 mph: 2.3 seconds

0-30 mph: 4.1 seconds

0-40 mph: 6.6 seconds

0-50 mph: 12.3 seconds

Top Speed: 53 mph

1/8 mile: 11.8 seconds @ 49.6 mph

That's very car-like. I don't know how close reality will bring me to the above figures, but my acceleration will certainly be adequate for merging into traffic and accelerating like a low end car.

With modifications, the Leafbike motor could be allowed to peak at 10 kW. This will require drilling holes in the casing and installing fans. I plan to start with 4 kW, because among those on endless sphere who have used this motor, unmodified, the general consensus is that you won't hurt it at 4 kW. At 10 kW, acceleration would start matching some $30,000+ modern sports cars, *if* I can get enough traction(highly doubtful).

Quote:
Have you compared estimates between fairing the wheels separately vs installing a 40" door? Some houses are much improved by double doors, too.
Installing a door is not an option. I don't own the place I live in, and the landlord is not keen on the idea.

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Old 08-21-2017, 11:06 PM   #34 (permalink)
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The Schwalbe Crazy Bob is available in 26x2.35 and is rated for E-bikes. Weight distribution and tire pressure are key in maximizing traction.
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Old 08-22-2017, 08:39 PM   #35 (permalink)
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Make the head fairing detachable? The book by Katz I purchased on Amazon; there is a 2nd ed.
It isn't just specifically the front that is going to pose clearance issues with the door. The trike can always be tilted on the side no matter how wide it is and slid through as long as the height of the cover piece over the rider's legs was skinnier than the door. But the height is also 1 m from ground to the top of the turtledeck. The widest point will ideally be where either the axle line for the front wheels or steering bars are, depending on shell. My initial bluff body design had max width in all three sections, BUT since the rear end will house the turtle deck and also future roll protection, I can tilt the trike back to original position and fit the rear through, if I leave an opening in the midsection to fit me through the door while I hold the trike tilted, and if the trike is narrow enough that I can do this easily standing on the steps while sliding the back end through the door.

If I make the body as wide as the trike width, even if the front section were completely removable, I wouldn't be able to fit it through once I tilt it back if I want to have a decent taper and avoid having to stand 2-3 feet from the doorway trying to hold this thing by the front after carefully balancing it in place and avoided dropping it while trying to get down some stairs.

Also, the bottom and rear must be attached the the frame in some manner to be to my satisfaction. I don't want the body coming off and cutting me in the event of a wreck. I will be building a frame for this body as well, possibly out of PVC pipe, but a metal mounting bracket is all I think I will need to begin using it reliably, if not yet safely, having already mostly finished a body that will go unused/unfinished and beat on it a little for testing. Coroplast is surprisingly strong stuff, in spite of its weak points.

I'm still working on the new drawing based on Phil Knox's input. It will be a simpler shape by far than what I was first building, and will be designed to allow sections to be cut out in the future for modification that is cosmetically pleasing(doesn't leave excessive errors with zip-tied repairs everywhere to make it more aero later on).

Give me a day or two and I might have the drawing done. I'm off to go on another ride before it gets dark.
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Old 08-24-2017, 06:49 AM   #36 (permalink)
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The nose is too blunt. Check out Velomobiles Coroplast and Recumbent Homebuilt groups on facebook and the Recumbents.com site.

https://www.facebook.com/groups/1564...ocation=stream


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I've been putting together an electric assist velomobile with the goal of approaching less than 10 Wh/mile at 30 mph on flat ground with the rider pedaling with an input of 100W. I want to make sure that I have the body streamlined to a decent degree. The first body, depicted in this post, is being made out of corrugated plastic. It is not good at making compound curves, and generally only likes to be folded in one direction. I came up with the design below based on the Rumpler Tropfenwagen and the lakester salt flats racers, with a bit of influence by the LeMans velomobile. After that is a picture of the trike as it exists today. Open wheels are a necessity in order to fit it in and out of my doorway, and the body width is as narrow as possible while still providing clearance for the steering bars and without the wheels scrubbing. I estimate a frontal area of 0.6 m^2, but I am hoping to get a 0.25 Cd or below. Better shapes will be built after this one, but this will be the starting point.

The drawing of the body is done to scale. 1 square in the blue grid is 100 mm.
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Old 08-24-2017, 10:54 AM   #37 (permalink)
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Old 08-24-2017, 01:24 PM   #38 (permalink)
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Tony is a top notch builder who has helped a number of people at recumbents.com. Coroplast comes in a hex cell form now so check a local supplier for sizes and prices. I have used semi flexible 5/8" OD PVC tubing from a plumbing supplier as supporting hoops for my fairings.
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Old 08-24-2017, 03:15 PM   #39 (permalink)
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Tony is a top notch builder who has helped a number of people at recumbents.com. Coroplast comes in a hex cell form now so check a local supplier for sizes and prices. I have used semi flexible 5/8" OD PVC tubing from a plumbing supplier as supporting hoops for my fairings.
I couldn't find that as a Coroplast product, but polyproplene is also used for PP panels

They claim heat-formability, which probably means "with less fuss than corrugated."
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Old 08-24-2017, 07:09 PM   #40 (permalink)
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Home Depot supposedly has 4x8 foot panels reasonably priced. Use the 4mm thickness. Corrugated polypropylene copolymer sheets. I got mine from a local plastic supply house for about $10 a sheet.
https://www.copeplastics.com/coroplast.html A print shop may have some in stock or could order it for a premium. The hexcell you are referring to is probably more expensive to manufacture, but interesting.

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