Existential crisis of criteria?
Things have been quiet here at Project Streetliner for a while. Progress is paused on my small-scale prototype while I wrench on a pair of old motorcycles. Meanwhile I've had a lot of ideas rolling around in my head. Thing is though, these haven't been ideas of progress, but rather ideas on how this project might drastically change.
Right now, the vehicle is designed as a tilting, petrol-powered, highway capable commuter vehicle. Thing is though, my commute now is mostly city streets. Do I really need to do 70 mph? If I'm just zipping around surface streets, is the leaning really needed? Is there actually an opportunity to do a full EV or an EV + generator hybrid vehicle? That has me wondering if I shouldn't re-spec this project for something closer to my actual use scenarios. Should I shift to more of a velomobile-style bike path runner?
For example, one idea I keep thinking about is basically taking apart a golf cart f0r its motor and controller, welding up a custom solo frame, then maybe adding Honda's smallest generator for onboard charging. If it'd just be a bike path / lane vehicle, then there's no real need for a full cage. I'd still be wrapping the whole thing in some sort of aerodynamic body. That'd be pretty sweet.
The other idea I keep tossing around is a non-tilting version of the Streetliner — something perhaps a tad lower and a bit wider up front. This concept would still be scooter or motorcycle based and highway capable, but having a flat trike setup means a slightly simpler chassis and suspension setup. I'm really ambivalent about this one, simply because it isn't that much of a complexity save. It would mean a control change that could be nice — that is, I could use conventional car controls rather than a handlebar and motorcycle controls.
Speaking of motorcycle drivetrain, that's been on my mind as well. I understand those mechanicals a LOT better than I used to. An older, air-cooled japanese motorcycle engine is simple, reliable, powerful, and even reasonably efficient. Parts are still abundant, and whole, running motorcycles are available for less than $1000. Changing sprocket sizes for different gear ratios is really easy if I go the motorcycle route. That coupled with the aerodynamic gains from the body shape should make my 60 mpg goals pretty easy to reach. The disadvantage there could be weight. But if my efficiency goals can be met, then does an extra 100 lbs really matter?
The last conceptual quandary I'm trying to figure out is broader purpose. That has a couple of connotations. Do I optimize the vehicle as an in-town commuter with highway capability for getting around town on the bypasses? Do I optimize for surface streets only — so a top speed of 55 mph or less? Or do I optimize the Streetliner as a long-distance touring vehicle? A coast-to-coast road trip at 60+ mpg would be pretty cheap to do. But it's not just me these days. For a long-distance tourer, I'd want to be able to have my wife with me and we'd need at least a little luggage space, even if we're traveling light. That's a pretty big change to design criteria. I'm open to it, but like any of these questions, it's a significant shift from the current concept. Decisions, decisions.
Any thoughts?
August 3rd, 2010 - 12:09
My opinion.. There are so many possible choices that you’d get lost in the vision and never get anythig finished. Pick something close, even if it does not exactly fit your needs/wants, get it out on the roads, and then revise and improve it after you see what you’ve got.
Simplify the steering, keep it with at least enough power to do short highway speeds if needed. Lots of choices for power, again I’d go with the easiest to fit your needs and budget.
I love the body shell design, as well as the concept of an efficient simple commuter vehicle. Can’t wait to see it on the road..
August 3rd, 2010 - 12:14
Thanks Steve, I think you’re right. It’s definitely easy to over think the whole thing. I think I understand the best combinations of things for the given purposes I have rattling around in my head, I guess it’s more about figuring out which purpose I really want to focus on. You’re right though, finishing is what matters. Delivering an imperfect vehicle is the best possible outcome and is at worst the stepping stone to something better.
Also great to see somebody from the MINI community!
August 3rd, 2010 - 12:31
DB linked you from WRR a while ago and I’ve been following since then.
My good weather commuting is done via motorcycle, and bad weather in the MINI, but something similar to what you are thinking of would work nicely for my 30 mile round trip commute (although I am 3/4 urban highway, speeds 50-70 so a bit bigger/more powerful would be needed to keep up and stay out of trouble)
August 3rd, 2010 - 13:36
Sounds familiar! I alternate now between my motorcycle and my Vespa on good-weather days and it’s the MINI the rest of the time. A lot of what motivated this project was trying to have a safer, easier cold and rainy weather vehicle that still felt mostly like a motorcycle. I doubt it’d be something that I could ride around in the snow and such, but on dry days when it’s simply just cold, that’d be the ticket. But beyond that, I think it’d be a great cross country adventure vehicle. A backroad, Route 66 kind of vehicle where the mileage would be so good that just striking out over long distance would be hard to resist.
August 3rd, 2010 - 14:08
Honestly, a long distance vehicle would be tough to do.
Lots more to worry about for sustained higher speeds.. comfort, durability, noise, vibration, and even aerodynamics and stability are things that can be ignored or downplayed on a short commute vehicle but would be more important or critical on a highway trip. Does sound like a fun thing to do though.
Sorry for hijacking/monopolizing your thread. Feel free to edit or remove if I’m too far off your topic. I’ve enjoyed what you have put into this project so far, and am looking forward to seeing where you go with it!!
August 3rd, 2010 - 14:59
Oh not at all! Thanks for chiming in. I don’t think I agree with you though, at least in the sense that a long-distance vehicle would be more difficult than what I’ve already got in my head. What I mean is that those things that you mention are all things that I’ve considered baseline for this project no matter what. It wouldn’t be a vehicle that could “only” be good for a basic commute. Regardless of commute or road tour, it should be a solid thing with power to spare at any speed it’s expected to cruise at, and driver comfort fit for any road mission on paved road. It’s a mix of things. On the one hand, I wouldn’t build a semi-capable “city car” (even though that’s how db keeps describing it). On the other, my expectations in terms of quiet, comfort, or noise would be realistic to a vehicle of this type. That is, I’d expect to still be wearing a helmet and even it being open top most of the time. So when it comes to noise or creature comfort, I wouldn’t ever be shooting for some sort of Lexus quiet cabin or real air conditioning.
It’s funny. As I write that, I realize that what you bring up makes total sense in the context of the indecision of this post. But in writing this response, I think I’ve just thought through and solidified the vision in my head. It’s got to be a vehicle that’s touring capable, thus making it over-built for my simple city commute — even if that is the bulk of its use. That seems like the only worthwhile thing worthy of this much time and expense.
So yeah, THANKS! I think that’s done it, at least in terms of purpose. I’m still ambivalent about fixed vs. tilting suspension. I think that finishing my prototype will help answer this better than anything. Neither is really that much more or less complex. The advantages gained in dynamic stability by leaning are really hard to ignore. It also makes this vehicle very, very unique. I like that.
August 4th, 2010 - 06:59
IMHO… I’d say to go with a small ATV engine for several reasons.
1) They are virtually identical to many motorcycle engines, except their gearbox has reverse, which will save you a lot of hassle later.
2) Many of the “manual shift” variety have an automatic clutch, which will gain you most of a scooter’s “twist-and-go” convenience while still keeping the ability to gear up simply by changing sprockets (something you can’t do easily with a scooter – see Craig Vetter’s woes with his Freedom Machine). Even if you decide to go with a CVT ATV instead of manual, you can still run a sprocket/chain off the bevel drive that normally drives the rear axle.
3) ATV engines are commonly larger bore single cylinders which are setup to generate a lot of low end torque, which will be useful after being geared up to your desired top speed. Many small displacement motorcycles don’t have a lot of torque and may have to be geared down to move a heavier vehicle then they were designed for as quickly as you’d like (especially if you decide to make it a 2 passenger trike).
4) Depending on what you decide to do about the front suspension, you may get many of the parts you need right off the engine donor.
5) If your EV desires grow, you can always retrofit it with one of the Motorcycle EV Conversion kits coming out lately. That option won’t be as easy if you start with a scooter engine/swing-arm/wheel.
6) And last, I don’t think the hp difference will be enough to limit you to surface street speeds with a gearbox to choose your final drive ratio. With a CVT or EV you have the problem of being “wound out” at your peak RPM and not able to accelerate further. Craig Vetter had this problem as well. With a gearbox almost any engine that will move you 55 with “power to spare” (as you dictated) will also get you to 70 for highway runs.
August 5th, 2010 - 13:33
Aaron, you are not wrong. You’ve made the case for the ATV drivetrain before, and when you did I was a lot less familiar with powersports mechanicals. That’s changed, but I hadn’t thought about the ATV drivetrain. It’s brilliant, actually. It’s even more frankenstein than using scooter gear. Love it. Looking into it now. ATV engines are available in a variety of sizes including the 400-650cc range I’ve been thinking for this vehicle. Let the research commence.