My Velo Pedal Car Prototype

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nerdalert

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Mar 22, 2015
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A while back I decided I wanted to turn a motorcycle into an EV bike. After internet sleuthing I came to the conclusion that wind resistance at highway speeds makes for some expensive battery/motor/controller combinations, and my motorcycle already gets 50mpg+. So I decided to build an electric bike. But then I moved to the pacific northwest and the need for a roof over my head came. I decided with a roof I need another wheel. So I started designing. Internet searches returned velomobiles, which I think are cool, but I feel like their low profile is asking for trouble in traffic, flag on a pole or not. It needed to be lightweight, easy to sit down in, low rolling resistance, and as little aerodynamic drag as possible despite electing to not make a low profile layback velomobile. Above all it needed to be practical. This is what I came up with :

g8WXoP6.jpg


I know you're thinking "That's an ELF!" Well, I hadn't seen the ELF until I was already welding the frame together from a 3d model I made when I came across it on YouTube. When I try to think of a strong design that works with aluminum and remains as light as possible, this is all I can come up with. That's my story and I'm sticking to it. However, looking at their design since then has influenced some of my own design decisions.

I elected the make the prototype as cheap as possible without skimping too much on quality. I've put quite a bit of money in it despite that. Some parts such as the pillow blocks and flange bearings are going to be swapped out with machined and welded in stem tubes for pressed in taper bearings for the lower bearings and bushings for the upper supports to save weight once I've proven the design to myself and done a little testing. I had the heavy bearings laying around already. No pedaling components until after testing.

I've got pretty much everything figured out except for the body. Not a clue on that yet. however the skeleton will provide trussing for the main frame. It'll tie in much the same as the ELF's does and the storage above the tire is an idea I will certainly steal.

I work on it every day so I'll keep you guys updated with pictures. Feel free to share your ideas and ask questions. I might skip putting the brakes on and do the wiring this weekend and take it for a spin.
 
The ELF has terrible aerodynamics.

The body I've designed for my trike is heavily influenced by the 1921 Rumpler Tropfenwagen. I don't have any pictures yet since I have yet to build it, but I think it's a good place to start for a simple, low-drag, practical shape. That car had a 0.28 drag coefficient, all with exposed wheels, and doesn't require complex curves, which is easily doable with corrugated plastic, wood, or a wide array of materials.

If you get your frontal area low enough, you could end up with a lot less drag than a standard bicycle, especially if you fit individual farings over your front wheels to maintain laminar flow across as much of the vehicle as you can manage. I think a Cd somewhere in the low 0.2 range is not out of the realm of possibility

The prospect of thousands of MPGe is very enticing.
 
That rumpler design is really cool but my current chassis may not be great for implementing an aircraft style nose without compromising the short length design. I need to take a side picture and start sketching. Show me yours.
 
Yes, I saw it a few days before my post. New here. Gotta take notes on the body construction
 
Rode it today at 48v. Pretty impressive speeds. Crawled up a steep hill at 5 mph. 1000w would be enough with light pedal assistance for even the steepest hills. 1500w 72v will be perfect. Need to lower the seat as much as possible. Was putting it on 2 wheels with fast, sharp turns
 
That sounds awesome! I have a home-made electric scooter (the one in my profile pic) with 48v 1000W hub motor that looks similar to yours. 20" wheel. We have a steep hill here I tested it on and it easily does 30km/h (18mph) without a problem. It doesn't have pedals. Your hill must have been pretty steep!
 
Looks like tons of fun :) That has a ton of acceleration. 72v would have you pulling wheel spins!
Question: why did you build all that camber into your front wheels? Almost all the reading I've done so far in to recumbent trikes keeps the wheels as vertical as possible, or perhaps a tiny bit of camber. I'm very curious!
 
When I was designing it my idea was that the outside wheel when you're cornering needs to be cambered to keep from folding. When you're cornering really hard you can hear that outside Tire really work working.
 
nerdalert said:
Show me yours.
Click to expand...

Here is a link to pics of my trike:

https://endless-sphere.com/forums/viewtopic.php?f=3&t=66772&start=100#p1196844

The only thing original that is still on it are the trike frame, seat frame, and handlebars. It's been restored/modified for the purpose I intend for it.

I will post pictures of my body designs whenever I hook my scanner up, but in my topic, not this one.

Ideally, you want a shape that uses complex curves, but unless you're working with fiberglass, carbon fiber, wood, ect., you're going to need a body that is simpler to build, or end up spending hundreds of hours and/or thousands of dollars. In a velomobile, aerodynamics is everything, and without complex curves, there will be a limitation to your efficiency. That being said, unless you know a few things about aerodynamics, figuring out how to shape complex curves to your advantage could become an issue too.

The most efficient commercially-available velomobiles that I am aware of are either the DF XL or the Milan SL. They are great shapes to look at for inspiration, but also extremely difficult to replicate and will require lots of time/money. The Milan SL has a Cd of 0.08 and can be pedaled to 30 mph on flat ground with only 150W. I'll be happy if I can get 30 mph on 300W.

For a more simple shape to replicate that sort of resembles what I am doing, check this out:

http://kenstewartartist.com/charles-trike-layout-1/#main

My design is somewhat similar, inspired by the Tropfenwagen, and will be posted sometime in the near future.
 
Rad! What's the body progress? After I swap out the lower bearing flange for a machined and welded in bearing stem I'll buy myself a good bit of room to drop the frame as the spokes nearly scrub the flange bearing currently. Sure is nice owning a lathe :D lowering the rear end is as simple as slotting a taller piece of aluminum angle for the rear axle to slip in but also raises the chain path. Trying to avoid the weight of idlers or jackshaft
 
nerdalert said:
Rad! What's the body progress?
Click to expand...

Check my topic. Not much, although once I get that sheet of plywood I need, it will take off from there. Since I have a camera now, I will be sure to post pics.

After I swap out the lower bearing flange for a machined and welded in bearing stem I'll buy myself a good bit of room to drop the frame as the spokes nearly scrub the flange bearing currently. Sure is nice owning a lathe :D lowering the rear end is as simple as slotting a taller piece of aluminum angle for the rear axle to slip in but also raises the chain path. Trying to avoid the weight of idlers or jackshaft
Click to expand...

Do you have any plans to add suspension? I would recommend it. My recumbent with suspension is a lot more comfortable than any un-suspended bike I've ever ridden. I could literally ride for hours and not get fatigued, versus an upright bike.
 
If there is going to be a suspension it'll probably be rubber donut bushings under the lower bearings and a flange welded onto the kingpin. I find 26" wheels very smooth across the bumps. It's a commuter
 
You may want to consider the design properties of the Leitra velomobile. It seems to be a practical body shape that is ideal for the application that you mention.
 
I appreciate your help but that is the most hideous thing I've ever seen. I don't want to trade in my car AND my self respect. :D :D :D The LYNX ride in the previous link you posted is more my style. I think his is beautiful and I wouldn't change a thing, aerodynamics be damned. Something between his ride and the ELF are my style.

I understand inverse square law and drag coefficient. but I want to keep the feeling of being out in the elements. Probably not going to have doors or a floor like the ELF. My motorcycle could be made faster or better if it were more streamlined, but that's compromising what it means to be a motorcycle, if you know what I mean.

I want to keep the feeling of riding a bicycle intact. I want the rider to be able to see the tires on the road below them, the steering linkages at work, the wind blowing across them, and the sounds of the wheels gnawing at the road in a turn. Something that when someone walks past it at the grocery store they'll think "that's something I could ride and I would like to own and looks easy to step into and go for a spin" and not "that's a specialized ride for a bicycle enthusiast for a niche market."
 
Very sorry, Toecutter, but I agree with nerdalert. That ride is not the prettiest vehicle I've ever seen!
Nerdalert, as far as I know the ELF doesn't have a floor or doors? :) I think doors might be an optional extra.
 
I like it! Since the rear end isn't part of the enclosure, a lot of storage potential is wasted. Grocery trip storage is critical. Also, high CofG. Hard carving in the corners, curb climbing, is essential requirements. A balance of utilitarianism, comfort, and performance. Like a WRX Wagon.
 
Ah - I think I got what your after. I'll post anything else I see that might be relevant.
Just got word my wheels are shipping! I'm pretty excited :)
 

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Yeah, you get it! Those aren't energy conserving wheels for sure. Decided I'm going to make flanged bushings for the lower bearings up front.
 
One thing (of many) I don't have in my shop (yet) - a lathe. Looks great!
And yep, energy conservation is not what I'm going for with those wheels :) They're about 50/50 looks and comfort - they are the only suspension. Also, I don't like the way that large vehicles (larger than a bicycle, I mean) look with bicycle-sized wheels. They somehow look a bit anemic and precious.
 
I can't read the markings on them--are they moped/mc tires? If not, I'd definitely recommend some. I switched to Shinko SR241's on my rear wheels on SB Cruiser, and it makes a HUGE difference in both ride and durability.
 
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