Shape Study #3

This is Project Streetliner Concept #3. After watching Gizmag’s fantastic video on narrow and single track vehicles, I wanted to explore a form that was as narrow as possible. More specifically, I also wanted to explore what the original kernel of my idea would look like. That is, if I took a Piaggio MP3, stretched it into a recumbent form factor, then built an aerodynamic body shell around it, what would I have? Well, I’d have this. It’s very trim and very shapely and definitely pays good homage to its Velomobile roots. Of my concepts so far, it would stand to reason that this one would be the most efficient in terms of aerodynamics, but I’m ambivalent about something so narrow. This is mainly because of low-speed stability and the need to put a foot down or not. Riding a normal MP3 is really no different than riding a standard 2-wheeler except that under just the right circumstances, you can lock the tilt at stop lights and things like that. That works for those situations, but there are times when you need to unexpectedly stop and catch the bike with your feet. If you’re already leaned over, locking the tilt isn’t going to keep you from falling over. However, if the front wheels were a bit further apart (like Concept #2), I’m optimistic that an on-demand tilt lock would keep the vehicle from tipping over in a sudden stop situation, even if the vehicle is fairly well leaned over.

As much as possible, I want to avoid having to Fred Flintstone this vehicle (that is, have my feet hanging out the bottom), including when I need to back up. But that’s a separate problem.

All in all, having shaped Concept #3 I think that I’m getting closer and closer to a final idea and that this idea will ultimately be somewhere in between Concept #3 and Concept #2. It’ll be restricted to half the width of a conventional car, but that’s still quite a bit wider than the Piaggio MP3’s current wheel span. Perhaps that’ll indeed be the sweet spot.

So why is tilting so important?

Some may wonder why I’m insisting on a tilting 3-wheel design for Project Streetliner. Watch about :30 of this video and it’s pretty obvious. The trouble with non-tilting trike is well explained by Wikipedia:

The disadvantage of a rear drive, non-tilting three wheel configuration is instability – the car will tip over in a turn before it will slide, unless the centre of mass is much closer to the ground or the wheelbase is much wider than a similar four wheel vehicle.

So unless the wheels tilt, you’ve got to essentially crawl around corners. I’m not planning to race this vehicle, but I do want to be able to take evasive action in traffic. So tilting it is! A vehicle like the Morgan was low enough and wide enough that it doesn’t really have this issue. But if I want to really benefit from a smaller frontal aerodynamic cross section, I’m going to need to keep things narrow. The advantages of a Piaggio MP3-style front end keep piling higher and higher.

Gizmag’s comprehensive review of narrow-track vehicles

Gizmag is one of my favorite new tech news sources precisely because of their affinity for new vehicles. This video is a fan-tast-ic overview of all the single and narrow track vehicles in the pipeline right now. They’ve put those innovations into very sharp perspective as well — laying out the reality of traffic congestion we’re going to face in the next decade and beyond. With the number of cars on the roads worldwide set to double in that time period (greatly outpacing the growth of road infrastructure), one of the best solutions may indeed be smaller vehicles optimized for efficient commuting. Narrower, nimbler vehicles means not only drastically less fuel consumption, but less congestion.

What this means for Project Streetliner is that I’m re-evaluating width. The seed of this idea was essentially for a recumbent version of the Piaggio MP3 with a streamliner shell on it. In the video, the presenter talks about how the Nissan Land Glider concept began explicitly with a half-width vehicle. In my mind, a vehicle like Concept #2 would be about 2/3 the width of a standard car. If I adopt a more narrow track and shroud the vehicle more like a Velomobile, that could make for a very interesting vehicle.