Entry/exit cutlines and mechanism

People have been asking how getting in/out of the Streetliner is going to work, so I’ve rendered what that might look like. In concept, the canopy (when attached) will hinge along the right-hand side of the vehicle, and a car-style door will open on the left-hand side of the vehicle. (I’ve also added a lip to the wheel pants to kick the wind off the surface of the wheel just a bit. I really like the look of this detail as well.)


Thoughts on the canopy

While discussing the Streetliner with my collaborators at work, the subject of the canopy came up. That sparked an idea for me. Rather than having to form (or pay to have formed) a singular canopy, it’d be a lot simpler to build the canopy in sections. Each of those sections would be much smaller and much easier to make. I think I could pretty easily create forms and heat-bend polycarbonate panels for the windows and windshield. In fact, in this configuration, a glass windshield might even be viable if it weren’t too expensive to get fabricated. But beyond ease, having a roof on the canopy would mean the cabin would be cooler. It’s also that much meaner looking. I like that too.

Entry and exit: its ramifications on exterior design

There’s been a lot of activity on the Streetliner drawing board this week. If you’ve been following along, you’re familiar with the shape above. This ’30s era race car inspired shape is what I’ve been showing people when they ask about what I’ve got in mind for this project. I love it, but I knew all along that this shape would inevitably change and evolve.

Likewise, one major aspect of the Streetliner’s design had yet to be worked out in concept: entry/exit. How the hell do I get in and out of the thing? It’s not that entry and exit is terribly complex, but in figuring out a good way to get in and out, it meant big adjustments to the exterior design of the car. So like any design undertaking, this needed criteria.

  • The integrity of the safety cage needs to be maintained as much as possible
  • Getting in and out has to be simple. No folding myself up snaking through impossible openings
  • I must be able to exit the vehicle even if the primary door system fails


So starting with the current exterior design, a handful of things have been adjusted since I first penned Design Concept Alpha. The overall length increased, the front wheels got larger, the wheel pants got longer and no longer turn with the front wheels. I really like this shape overall. The snout shape of the front end is very pleasing, the rear has a lovely duck tail quality, and I especially like this design because the vehicle looks even better with its canopy on. All of that shape, however, is mated to an underlying safety cage and chassis:

With arches as the vertical pieces, the safety cage design is pretty straightforward. Heavy duty curved bulkheads are connected by heavy duty rails, then everything is cross-braced in a truss of smaller diameter steel. The angled front and rear main plates actually create rudimentary “crumple zones” where impact damage would send the motor assembly and or front suspension components under the vehicle in the event of an impact. This design is structurally sound, but it has one major flaw: how the hell do you get in and out of the thing? The height of the cockpit opening lip is right at 36″ in this design. I’m pretty tall, but that’s still quite a height to throw a leg over while getting in and out. I also realized that I’d only given myself a 24″ deep opening front to back. I’m not a whole lot narrower than that myself (it’s winter weight, I swear!). So the practical concerns of getting in and out of a high, narrow opening are pretty significant. But even beyond entry acrobatics, with such a narrow opening, I wouldn’t be able to see my hands or any cockpit gauges. That top opening needs to grow and dammit, I need a door. The tricky bit is how do I add a door without compromising the safety cage?

One thing at a time. I added an approximation of the front suspension “box” and see where and how that should tie into the frame. I lowered the bottom rails to tie in to the front and also simplify the rear subframe where the mono-shock would attach. I also moved the main roll hoop back just slightly where previously it was implied that it would overlap my shoulders. Upon further reflection, I realized that this being a single seater, I only need one door. Even though my diagrams here show the opening on the left side, I think I’m going to opt for the right side having the door. Since the majority of motorcycle accidents involve people violating your right of way from the left, it makes sense to me to leave the left side solid. That written, the underpinnings of the door as I’ve envisioned it are as substantial as the major parts of the cage. That way when it’s closed and latched, the door becomes part of the safety cage. I like to think of it like the harness that comes down and locks in when you get on a roller coaster. Solid. Also, thinking about an impact scenario, that’s a force into the cage, so if the door is structurally captive against being pushed through the opening, it ought to be as good as solid. With the door opening on one side of the vehicle, the canopy (when attached) could hinge along the opposite edge — making for a very easy time getting in and out.

With that adjustment made to the frame, the body shape needed adjustment, as you can see below. The opening needs to be increased to meet my design criteria for being able to exit the vehicle in a pinch through the top without using the door. The bottom profile of the body shape also needed to be adjusted to account for the front suspension box.

Now with the shape updated, I like it even more. The larger top opening not only gives the whole vehicle a better proportion. It looks smaller and more trim overall. Before now, with the length being about that of my MINI (which I know, isn’t exactly big), the Streetliner has looked strangely large. Now it looks much more like the race car cabin scooter it was always meant to be. I also reshaped and shortened the wheel pant to account for the door opening.

I really felt like the new shape came into its own with the canopy in place. Not only was it less bubble-shaped, but it completes the curve created by the tail. I can also imagine much better visibility and comfort within the cockpit. That led me to consider some alternate front end shapes. One of which was the sloped, Ferrari GT-style nose. It would borrow its hood scoop aesthetics from a different era than I’d previously been thinking, but I really like it. Forward visibility would be better and overall aerodynamics might be a tad stronger with this sloping approach.

All that remained at this point was to add some visual interest to these basic shapes. This included sculpting the rear and adding a sort of LeMons-style front lip to the wheel pants. I really don’t want to overlook subtle details throughout the shape. Sure, a perfectly smooth Velomobile kind of shape is terrifically aerodynamic, but without at least some minimal sculpting, I think the shape would look like it were stuck in the ’70s and just generally unfinished. These details will surely evolve as the project progresses, but I’m loving it so far.

As I look back on the progression, it’s amazing how much influence a little thing like a door can have, but all for the better! This shape still has a lot of classic Italian sensibility, a lot of race car mojo, and plenty of salt flats shape credibility. As much as I love the ’30s sensibility of Concept Alpha, I like this even better. But more than that, I’m glad to have another big piece of the conceptual design puzzle in place.



Some thoughts on reverse

This vehicle exists in sort of a strange place in-between being a car and a motorcycle. It will lean like a motorcycle and utilize big scooter mechanicals, but it will also be enclosed like a car. There will be no need to put my feet down at intersections, because a simple on-demand locking system on the tilting suspension will allow the vehicle to stand on its own three wheels (which will also remove the need for a side or center stand). Being enclosed will mean both comfort, aerodynamic efficiency, and actually a large amount of safety. There really is a lot of elegant convergence here. The locking tilt actually enables me to never need to put my feet down, which makes enclosing the vehicle easier with no need for holes or “bomb bay doors” to pass my feet through. What I have yet to figure out, however, is how to back up.

You simply can’t not have reverse. Sure, most motorcycles / scooters don’t have a reverse gear, but you still have to “walk” them backwards to get out of parking spaces and other common driving situations. Some large motorcycles such as the Honda Goldwing do have actual reverse mechanisms, as do electric bikes like the Vectrix that use their hub motor for regenerative braking. But so far, I haven’t been able to locate a scooter in the 400-600cc range that includes a reverse gear. This year’s Honda Silverwing info says the following:

The V-Matic means no shifting, ever—not even into Neutral or Reverse.

This would seem promising, but a phone call to my local Honda dealer confirms that this is in fact just really, really bad marketing copy. So I’m at a bit of an impasse. Reverse is a must, but I can’t find it built-in to any of the powerplants I’m considering for this project. So I’ve got to figure this out.

Electric option #1: Hub motors in the front wheels
There are a couple of ways that I could utilize electric motors for reverse. One route would be to use hub motors in the front wheels and essentially make an electric hybrid. Piaggio has a hybrid version of the MP3 that does exactly that. Front hub motors would make regenerative braking available, and with that, reverse. The major, and in my opinion, irrevocable barrier to this option is its complexity and its expense. I’d likely have to purchase those hub motors directly from Piaggio and they wouldn’t come cheap. Then there’s the batteries, which add significant weight, and the added complexity of all the speed controllers and power management systems it would take to link the motors to the throttle and balance them against the IC engine. As cool as a hybrid would be, it’s an awful long way to go just for reverse.

Electric option #2: Drive the rear wheel on either direct friction, a sprocket, or a clutch
There are a number of electric and IC engine kits out there for motorizing bicycles. Many of these involve a friction roller that contacts the rear tire. Although probably not the most elegant solution, something similar could work very well. A small, high-torque motor like a wheel chair motor or a even an ATV winch motor could be suspended from a subframe that could be lowered against the rear wheel to turn it backwards. I’m picturing something like a hand-brake lever with a trigger button on it to run the motor. The Lightstar Pulse used a similar system, except that they used an aluminum cone pushed against the wheel rim instead of a rubber wheel on the tire. Online owners report that it’s adequate, although very slow and apparently a massive battery drain. I was already planning to run a significantly larger battery than would be standard in a scooter in order to support a handful of ancillary electronics, so perhaps that would be enough, presuming the bike’s stock charging system can replenish it.

One related idea I had in this vein would be to use a sprocket on the wheel that the motor could engage with its own toothed gear. Perhaps a starter motor/solenoid system would work. Apparently the Honda Goldwing uses a reversible starter motor for its reversing functions, albeit at the flywheel. The one thing I wonder about would be the wear and tear of that kind of engagement. As for the sprocket, I was thinking that I could just have teeth put on the rear brake rotor. It’d mean a bit of precision bracketry, but may indeed be the ideal arrangement.

The third variation would be to use a belt or chain drive between a motor and a sprocket/pulley on the rear wheel and be able to engage a clutch on that mechanism. Depending on how it was set up, it could even double as a low-speed charging system to recoup some of the energy used in backing out of a parking space.

Manual option #1: The Fred Flintstone method
Most velomobile trikes have a pair of holes in the bottom of them to allow the rider to back up under foot power.  This could work for the Streetliner, presuming I have enough leverage to scoot the weight from a seated position. Having a pair of permanent holes in the underside of the vehicle does not appeal to me at all. Nor does having some sort of door/hatch system. This thing is complicated enough. Although, I have to admit, there is an elegance to just hoofing it.

Manual option #2: Some sort of crank to the rear wheel
Perhaps some of the electric methods described above could be similarly executed with a hand or foot crank in the cockpit. I’m not looking for fast reverse, just enough to get in and out of parking spaces and perhaps back up far enough to then pull forward around an obstacle like a stalled vehicle. There’s something deliciously old-school about that, but it’s probably not the best solution.

Any ideas? I haven’t come to a solution I like yet. What haven’t I thought of?