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 KMX-based coroplast velomobile
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Toecutter
New Member

USA
57 Posts

Posted - 06/06/2018 :  03:40:20  Show Profile  Reply with Quote
The following images are month's old:





I've since made some modifications and am still tweaking the design.

I've placed about 700 miles on it within the last month and a half, and the body shell has seen thousands of miles of use already. It can carry $150 worth of groceries in the trunk space without issue and has held up great since January thus far.

I have a comfortable flat ground cruising speed of roughly 21 mph. It has proven itself to be stable at 45+ mph down hill, and I have no problem reaching well over 30 mph on the flat and have touched 35 mph using the 48T front ring a few times on what I judged to be flat surfaces(*edit: I just checked google maps. There's a 6 ft elevation drop on that stretch of Lucas and Hunt Rd, so 35 mph isn't my true flat ground top speed. I need to find a flat enough section of road around here to test that). There's a lot of room for aero improvements with this design as coast down testing showed a CdA around 0.25 m^2, which is far higher than the typical commercial velomobile. I intend to cut that down to around 0.1 m^2. My goal is to make the body efficient enough to cruise at 25+ mph on the flat and top out at 40+ mph on the flat purely on pedal power. THEN I'm going to add a motor.

I plan to add an electric assist in the future with 10+ horsepower so that it can out-accelerate most cars. I also want it to be functional with the motor disabled, so it needs to retain a wide range of gearing for me to get up steep hills.

A friend and I are in the process of building a new shell for it out of aluminum, mainly to learn how to work with the material so we can build a custom electric car. It will have reduced frontal area and greatly reduced drag coefficient over the current shell with the new floorpan copying a NACA0020 airfoil cut off at the tail at 87% of full length. If the shell proves too heavy for use in this vehicle, I will still be able to use it as a mold to build a replica from a composite material or maybe even do a close approximation in coroplast again.

Current configuration, weighing somewhere around 65 lbs:

-x1 KMX adult-sized steel frame kit
-x2 Velocity 20" rims, 14ga spokes (front)
-x2 Gas Shocks (front)
-x2 Schwalbe Tryker 20"x1.5" tires (front)
-x1 26" double-walled wheel with 12ga spokes (rear)
-x1 Schwalbe Marathon Plus tire, 26"x1.75" (rear)
-x315 links of KMC 8.93 3/32" 7 speed chain
-x1 DNP Epoch 7 spd rear freewheel cogset, 32-11T
-x1 Shimano Tourney 28/38/48T front cogset
-x1 Shimano 165mm front cranks
-x1 Shimano Tourney rear derailleuer
-x1 SRAM 7 spd shift knob
-x1 SRAM 3 spd shift knob
-x1 SunLite dual cable pull lever
-x2 Avid BB7 cable-pull disc brake rotors, calipers and metallic pads
-Lights, cables, mirrors, computer, ect.
-Coroplast Wheel disc covers (homemade)
-Coroplast body (homemade)

Future upgrades:

-more streamlined body shell
-x1 Sugino 153mm 6/7/8sp crankset modified with 34/46/56 gearing or maybe an Efneo with 152mm cranks
-x1 Cycle analyst computer
-x1 THUN torque-sensing bottom bracket
-x1 Leafbike 1500W in-wheel hubmotor
-x1 Sinovert 72V sinewave controller
-custom skid-plate and battery box
-Some sort of battery pack (will be sized appropriately to keep the vehicle under 100 lbs and provide at least 4 kW to the motor)
-Headlights, brakelights, turn signals, night lights(turn on at night to improve chances of being seen), better gauges(maybe ones showing heartrate in bpm, cadence, motor assist, motor rpm, mph, battery V, battery A, motor power, motor temperature)
-small auxillary battery with DC to DC converter and inverter for plugging in a laptop computer, cooking out of a crock pot, or charging a phone
-rack and pinion steering system so that the steering bars can be removed and a narrower body made/installed to allow frontal area reduction

Edited by - Toecutter on 06/06/2018 20:00:12

Jerry
human power supergeek

USA
1429 Posts

Posted - 06/06/2018 :  12:16:00  Show Profile  Reply with Quote
Sounds like it is fast. Take it to Northbrook in July. Also Cedar Rapids in September and Nashville in October. Sounds like you would do well at those races.
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Toecutter
New Member

USA
57 Posts

Posted - 06/06/2018 :  18:44:37  Show Profile  Reply with Quote
Gladly, if I can find a way to get it there. Maybe I'll ride it to Northbrook if I can justify the time it would take to do so, as it's only about 300 miles away.

The machine is not as fast or as aero as I was hoping, but it can always be rebuilt. It did exceed my expectations with regard to practicality though, and that was an overriding concern compared to speed, and I'm happy that it still provided a noticeable gain over the naked trike. I want to crack the 40 mph barrier like Orin Peters did with Hidalgo, and I'm not even close yet. I need either twice as much peak leg power(not happening unless I start popping steroids, and I won't be doing that) or less than half the drag(very doable, although that alone may not get me there).

I should get a camera and record a speed run with it. I've been meaning to, just never got around to it.

I'm never going back to uprights again. They suck.

This thing is awesome for doing 50+ mile rides in. I've ridden it all over St. Louis already. Without a drivers license, my electric car sits, and this is my transportation.

Edited by - Toecutter on 06/06/2018 18:48:22
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absiumhelp
Starting Member

USA
31 Posts

Posted - 07/24/2018 :  21:19:17  Show Profile  Reply with Quote
Good stuff! When can we expect the video?
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Toecutter
New Member

USA
57 Posts

Posted - 07/29/2018 :  20:36:38  Show Profile  Reply with Quote
I will get a video whenever I get around to getting a camera. I'm currently unemployed and am being extremely careful with my savings, but when I come along a camera at the right price, I will have something to videotape my use of this vehicle.

I may have the next body shell on it by then.

I also will probably have some kind of job with money coming in next week. Then I can justify the purchase of upgrades, and the camera(if the price is a little higher than I'd like).
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Balor
recumbent guru

Russia
697 Posts

Posted - 07/30/2018 :  09:21:07  Show Profile  Reply with Quote
You don't have a smartphone? It is not like we ask for a Hollywood-level filming :).
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Toecutter
New Member

USA
57 Posts

Posted - 07/30/2018 :  13:28:28  Show Profile  Reply with Quote
I do not have a smart phone. Given the degree of unwanted third-party monitoring present when using them, I refuse to own one. It's also another monthly bill to drain my wallet.

It looks as if I will be starting a crappy part time job soon. It won't pay nearly as nicely as my previous job as an Electrical Engineer did, but it will keep me from draining my savings and allow me to(slowly) purchase more parts with which work on my projects.

I had to quit my former job to move back home and help my mother.
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Toecutter
New Member

USA
57 Posts

Posted - 08/08/2018 :  23:14:05  Show Profile  Reply with Quote
Someone showed me some videos of my corovelo going down the street.

They sent me the link as well, but since I don't mess with facebook, I couldn't view it from my machine. Somewhere in the link below are videos of it:

https://m.facebook.com/groups/1473501216199125?view=permalink&id=2168739953341911
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Toecutter
New Member

USA
57 Posts

Posted - 08/12/2018 :  13:23:55  Show Profile  Reply with Quote
The above link was to a closed group. I got the videos off and they are now viewable below:

https://vimeo.com/284616898

https://vimeo.com/284616919
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Toecutter
New Member

USA
57 Posts

Posted - 03/29/2019 :  03:16:39  Show Profile  Reply with Quote
A few months ago I had to remove the body shell to do some work. The Shimano Tourney front crank got seized onto the bottom bracket and stripped its threading when I attempted to replace it with a Suntour XCT Jr. 152mm 22/32/44T crank. The 28T ring of the Tourney was bent from excessive torque and mashing up 20% hills in the 38T ring with 165mm arms was killing my knees.

The body was also showing its signs of wear and tear and developed a dangerous wobble at 40+ mph downhill, which adversely impacted the stability of the trike.

I started on a new body some months back, but it will be at least another month before it is ready. I'm hoping to cut the drag in half over the original shell I built.

Yesterday I started working on a tailbox for my trike to hold me over until the next body is ready, as riding it around without tools/parts/water is pushing my luck given the distances I ride. I found a 48"x32" sheet of coroplast advertising 32oz cans of Milwaukee's Best for 2/$2.22 flying around in a parking lot from the wind two days ago. I took the plastic sheet home, cleaned it up, and got to work.

It's going to contour to the rear of my seat, be 420mm wide(width of my shoulders with a leather jacket on), and taper back 12 degrees on the sides and bottom with a flat top including a hinged lid, with a total length of 520mm and a height of 280mm.

It's main function is to hold spare tubes, master links, tools, zip ties, and water, but I expect there will be a small drag reduction, as well as act as a rear wheel fender to keep spray from the rear wheel off of me. The tool boxes will be divided into two of 130mm width on each side of the rear wheel.
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Toecutter
New Member

USA
57 Posts

Posted - 04/20/2019 :  12:55:06  Show Profile  Reply with Quote
My current design that's in progress uses a NACA0023 of 620mm width and roughly 2.7m length for the top-down profile of the floorpan, and the side view of the main body uses a NACA2820 with the widest point being 620mm and cut off at 87% of the length. This side profile doesn't include the turtledeck or the windshield/roof, which are still being finalized and will be some variant of NACA00XX from the top and sides. The design is still open-wheeled, which adds a lot more drag than I'd like, and I've come up with a solution to mitigate this somewhat: fairings over the front wheels and brakes(like the Aptera 2e or Birk Butterfly) with a coroplast "slinky" with its side profiles shaped like a NACA airfoil and spandex covering the ribs of the "slinky" which then covers the suspension arms and brake cables, so that the shape can bend and flex as I steer and go over bumps. I don't expect or hope to get a Cd as low as a 2-wheeled streamliner, but I'll be more than pleased if I get a Cd under 0.20 and an overall CdA under 0.12 m^2.

I realize this shape is a starting point as well, and only my 2nd design iteration. I plan to make corrections after I discover its flaws. This body is already under construction using coroplast, and I'm doing my best to translate a compound curved shape to coroplast as close as possible in spite of its limitations(This one has a 6-sided front cross section). For lacking CFD software and extensive aerodynamics knowledge, I'm trying to get the drag as low as I can.

Edited by - Toecutter on 04/20/2019 13:57:37
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