Project: Home made velomobile design with crank or mid motor

tahustvedt

10 kW
Joined
May 26, 2014
Messages
595
Location
Northern Norway
I'm designing a velomobile to replace my car. I need something to protect me from harsh weather on my ride to work and the shops. It will be almost entirely home made, except for the wheels and bike components. Maybe I'll build the rear wheel myself, but I already got a good deal on the front wheels I want. It might get active electronically controlled suspension with lean/anti roll as well. I need it to be easy to build as I don't want to make huge molds, so I'm going with a combination of plywood and carbon fiber. The frame and suspension parts will be 6082-T6 aluminum. With a tilting steering wheel and "lambo-doors" it should be easy to enter and exit. I want it to be comfortable, not too laid back and visible in traffic, yet fairly aerodynamic.

I'm not decided on how to power it. I am limited to 250 W in Norway, but that's ok. I'm designing the frame so that I can use a Bafang crank drive up front, or lpaced in the middle behind the seat if I want to. That's the most practical option for me as I can then use a crank with a narrower Q-factor. There is also room for a hub motor in the rear behind the seat if I go that route, but I'm leaning towards a Bafang-unit for now due to its compact form factor. Battery size will be flexible depending on the needed range at any given time. There's a lot of room for batteries on each side of the seat under the floor.

Wheels will be 26" all around, with a fat bike rim and tire in the rear. Downhill wheels in the front with 20 mm hubs. The ability to lean according to G-forces using an accelerometer will reduce the side load on the wheels, but don't plan to do any tecnical racing with it. :p Air shocks all around and about 80 mm of travel.

There's easilly enough room for a 60W flexible solar panel on the roof, but I don't think I'll go that way.

Hoping to keep it around 50 kg, but I don't think that's realistic.
 

Attachments

  • Velo34.jpg
    Velo34.jpg
    106.2 KB · Views: 21,510
  • Velo35.jpg
    Velo35.jpg
    46.6 KB · Views: 21,496
  • Velo31.jpg
    Velo31.jpg
    71.9 KB · Views: 21,507
  • Velo36.jpg
    Velo36.jpg
    86.3 KB · Views: 21,526
There's a lot of velo build threads around here, but they're always light on info. Yours is already looking rather elaborate.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=25315
 
Dauntless said:
There's a lot of velo build threads around here, but they're always light on info. Yours is already looking rather elaborate.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=25315

That one was really nice. I haven't seen it before.
 
Very interested in this project! Will follow closely!
 
I just finished making the CAM toolpaths for milling out the lower suspension arms. It'll take six hours total to mill at a conservative pace. Lots of 3D milling and only one tool change. The picture shows one side of the arms before flipping over and milling the other side. They will be symmetrical. The shock absorber is going to connected between the arms.
 

Attachments

  • Velo38.jpg
    Velo38.jpg
    35.7 KB · Views: 21,116
I received some HTS 2000 aluminum brazing rods today. It's pretty great stuff. Even though I didn't chamfer the edges of the parts before joining, and didn't clean too well first, it worked great. I had to bang the top tube to an unrecognizeable shape before it started coming loose at a corner. I'll do another test with proper preparation later.
 

Attachments

  • Velo39.jpg
    Velo39.jpg
    82.8 KB · Views: 21,137
tahustvedt,

I would suggest that, given your obvious skill and equipment, a BBS01 would be a waste of money. In your application, it is no better, and in fact less flexible than a 250 watt hubmotor. If you run the BBS01 as a midrive, you have no use for the cranks and bottom bracket axle, or the proprietary controller. And, as you say, the Q factor makes any of the production bottom bracket drives less than ideal. Get a decent 250 watt hubmotor and mount it wherever you like.

http://www.evalbum.com/4525

Warren
 
Warren said:
tahustvedt,

I would suggest that, given your obvious skill and equipment, a BBS01 would be a waste of money. In your application, it is no better, and in fact less flexible than a 250 watt hubmotor. If you run the BBS01 as a midrive, you have no use for the cranks and bottom bracket axle, or the proprietary controller. And, as you say, the Q factor makes any of the production bottom bracket drives less than ideal. Get a decent 250 watt hubmotor and mount it wherever you like.

http://www.evalbum.com/4525

Warren

I'm still considering it. Won't buy the motor until I have a rolling chassis at least. I do already have a 250 W hub motor that I planned to make a mid drive from, but I just like the simplicity of the BBS01, and it puts out 520 W at full throttle. The most important thing is that it says 250 W on the housing in case someone feels the need to stop me to check. :D
 
tahustvedt said:
Warren said:
tahustvedt,

I would suggest that, given your obvious skill and equipment, a BBS01 would be a waste of money. In your application, it is no better, and in fact less flexible than a 250 watt hubmotor. If you run the BBS01 as a midrive, you have no use for the cranks and bottom bracket axle, or the proprietary controller. And, as you say, the Q factor makes any of the production bottom bracket drives less than ideal. Get a decent 250 watt hubmotor and mount it wherever you like.

http://www.evalbum.com/4525

Warren

I'm still considering it. Won't buy the motor until I have a rolling chassis at least. I do already have a 250 W hub motor that I planned to make a mid drive from, but I just like the simplicity of the BBS01, and it puts out 520 W at full throttle. The most important thing is that it says 250 W on the housing in case someone feels the need to stop me to check. :D

http://www.zazzle.com/custom_rectangular_sticker-217526402362397125 Maybe you could slap a custom sticker on whatever hub you get.

Something I've considered when it comes to velomobiles is that even if the motor is said to have a certain thermal capacity, I am sure they have that in mind for not being inside of a velomobile but moving with a bicycle at a certain speed in a very open to the elements sort of way. The motor being inside of your velomobile means no wind blowing over it. I could be wrong, but this has been a concern for me even with the idea of having a hub motor mounted in a rear motor outside of a velomobile. These are just my guesses though, I've never owned a velomobile so I don't really know how things will work out. But I'd be curious to see what your motor told you combined with a temperature sensor.
 
Yeah, I plan to duct air from the bottom if I mount the motor in the middle, and duct air from the nose if I mount it as a crank. I don't think it'll be a problem in the winter though.
 
tahustvedt,

"I do already have a 250 W hub motor that I planned to make a mid drive from, but I just like the simplicity of the BBS01, and it puts out 520 W at full throttle. The most important thing is that it says 250 W on the housing in case someone feels the need to stop me to check."

If the controller on your 250 motor is too small, get a bigger one. The sticker on the motor can stay. It is probably a 24 volt controller. Run a 36 volt controller and battery and gear the motor to spin 1.5 times faster than stock. More watts, and the heat will stay low too.
 
My controller is an infinity controller from EM3EV so I can run high voltage on it. I can make my own gears and sprockets, so I can run exactly the gear ratio I want and therefore up to 72 V if I want to. We'll see what happens when the time comes to motorize it. ;)
 
Beautiful work, man. Well done. :D
 
Thanks.

Here is the simulated result of the G-code for the top arms. The elbow shape is necessary to clear the bolt head. Though it's hard to tell from this one sided model, It is a little thinner (flatter) between the mounting points since it doesn't have to hold the weight, only absorb braking and cornering forces. I don't do any strength calculations. It's all based on previous experience and TLAR. :p
 

Attachments

  • Velo41.jpg
    Velo41.jpg
    32.2 KB · Views: 21,114
I ruined the top suspension arms during milling because the work piece was only just big enough, which limited clamping options, so it worked itself loose. I'll redo the arms when I get more material.

I added a standing person to my side plans to illustrate the size of the velomobile better. It's the same height as me, 179 cm.
 

Attachments

  • Velo42.jpg
    Velo42.jpg
    84 KB · Views: 20,874
I need to modify the spindles because I had a brainfart when I milled them. They are actually mirrored. If I hadn't drilled the caliper holes then it would have been easier, but I can save them quite easilly anyway. Hey. Maybe I can fill the holes with HTS 2000 and drill new ones. ;)

I received the front wheels yesterday. They are incredibly stiff, and I'm not worried about tacoing them in corners any more. They are suitable for downhill riding, with 20 mm hubs. Ill pop out the end cups of the hub and turn one of them down, and make a flange on the shaft I'm turning to sit against the bearing on the outer side.

I ordered a rear shock. 165x38 mm SR Suntour air/oil. The front shocks will have to wait until I get more funds. I'm going with 190x50 shocks in the front to have more lean range. It will only be able to lean a maximum of 6°to each side, but it will help a little, and worst case is that it will work as an anti-roll function at higher G-forces. I'm not sure if I will make an active suspension with an accelerometer or if I will just use a potentiometer/hall sensor on the steering system. I'll probably try both.
 

Attachments

  • Velo43.jpg
    Velo43.jpg
    133.5 KB · Views: 20,741
There, I fixed it.

I lightened it a little while I was at it. It's still beefy. 9 mm at the thinnest areas. The circular pocket between the bolts is to make room for the brake disc bolts. It all fits now.
 

Attachments

  • Velo44.jpg
    Velo44.jpg
    120.4 KB · Views: 20,753
I've started working on it again. I made a seat today. It looks ok, but it's a little too big for me, and overbuilt, so I will probably make a new one eventually with thinner material. A lot has happened with the drawing, and I'm pretty much ready to start routing everything. Materials are expensive though. I attached a side view from the current iteration of the velomobile drawing.
 

Attachments

  • Velo55.jpg
    Velo55.jpg
    130.2 KB · Views: 20,225
  • Velo56.jpg
    Velo56.jpg
    122.8 KB · Views: 20,223
  • Velo57.jpg
    Velo57.jpg
    64.7 KB · Views: 20,225
Nice and impressive works!

Have you considered buying premade seats? Alligt, NL sells a nice injection molded recumbent seat with two different glass fibre grades, PA6-GF30 and PA6-GF40:
http://alligt.nl/afbeeldingen/100_2268.JPG

The best thing is that a 3D CAD model of the seat can be found here:
http://alligt.nl/downloads/Alligt_zitje.zip
 
Yes I have, but it feels much better to make it myself. :)

I'm running CFD simulations of the car to try to figure out if it's ok or not. It's got about twice the drag og for example a Quest velomobile, which is ok, but I had hoped for better. I also made a model that resembles an Elf-looking car, and it has about three times the drag of mine. Not sure what to think about it all, and not sure how much I can trust the CFD. Maybe I should just accept that ultimate performance was not a primary objective with the project. I'm getting ~25 N drag from the simulation, but I have a feeling that it's less in reality, because the CFD can't simulate speeds below Mach 0 so I have to calculate down to 11,1 m/s afterwards.

The CFD I'm using is MicroCFD 3D Virtual Wind Tunnel: http://microcfd.com/software.htm
 

Attachments

  • Velo64.jpg
    Velo64.jpg
    59.6 KB · Views: 5,179
Back
Top