Enclosed trike / Velomobile dream

[John in CR]

swbluto,

I've all but decided to go with a construction method I used to build a sailboat. I used it to build a beach catamaran that's right at 5 meters long with an all up weight of under 80kg, and that's using some extra glass+epoxy layers in addition to what was called for by the designer. We're talking two 5m hulls and rigging for a strong seaworthy craft, so it approaches the lightest weight composite structures with very little build effort. Support framework would go away other than attachment areas to the bike, and the real beauty is the exterior turns out paint ready verses the weeks/months of work to prep those HPV velo's of composite construction.

The base construction material is very thin plywood, and my only concern is just how far I can bend it for the curves I need. I'll do some tests over the next week or two, and share the construction process in pics and clips section. I have no doubt that this method can produce a stronger, more rigid, and lighter shell than the corrugated plastic, without too much extra work, and almost no tools.

John

 

[swbluto]

swbluto,

I've all but decided to go with a construction method I used to build a sailboat. I used it to build a beach catamaran that's right at 5 meters long with an all up weight of under 80kg, and that's using some extra glass+epoxy layers in addition to what was called for by the designer. We're talking two 5m hulls and rigging for a strong seaworthy craft, so it approaches the lightest weight composite structures with very little build effort. Support framework would go away other than attachment areas to the bike, and the real beauty is the exterior turns out paint ready verses the weeks/months of work to prep those HPV velo's of composite construction.

The base construction material is very thin plywood, and my only concern is just how far I can bend it for the curves I need. I'll do some tests over the next week or two, and share the construction process in pics and clips section. I have no doubt that this method can produce a stronger, more rigid, and lighter shell than the corrugated plastic, without too much extra work, and almost no tools.

John

Cool! If the wood could be treated so that it'd be flame-retardant, that'd be a pretty sweet alternative.

Anyways, I was wondering about the "roll cage". I saw some normal car roll-cage listed weights and they were like 100-200 lbs for mild steel. Apparently cro-moly can be made a bit lighter, but it's tougher to get a reliable weld and so it isn't trusted as much as mild steel (And I certainly wouldn't trust with myself that much with welding). An alternative seemed to be some kind of T4x steel where I think x is 1 that seemed to be 20% lighter than mild steel and doesn't have as much issues with welding reliability.

I decided to get some info from wikipedia at http://en.wikipedia.org/wiki/Drag_coefficient, and here's the very informative graphic listed there.



It seems an angled side has about twice as large a drag coefficient as something spheroidal in shape, so it seems curved sides would be far better when dealing with cross-winds (half the force, assuming the same cross-sectional area). I kind of wonder what ellipses would have for a drag coefficient, or maybe a tapered ellipse.

According to http://www.unicopter.com/1021.html, an ellipse could get down to a drag-coefficient of .25 depending on the ratio of the length to height, so it looks like it could possibly be reduced to a drag coefficient from .47 of a sphere to .35 of a semi-ellipse in practice. However, that'll affect the frontal area as well, so that looks like it'd take some optimization. Eh, I'd just copy parts of aptera's basic design as I'm sure they took that into account.



Also, to revisit the viability of a trike in snowy climates, it does seem like it wouldn't be that good for snowy weather due to the increased drag from the three straight tracks. It seems the middle wheel would be particularly horrendous as that's not where the car's markings are, so I thought... let's extend the back two wheels to a normal car's wheelbase, and then let's make the front wheel interchangeable with a ski with the flick of a button.

Ok, so I'm dreaming, but it would sound like one way to go about it. I don't know how steering would be implemented, though...

So, in essence, I'm abandoning that idea.

Also, I kind of wondered - why wouldn't this thing be taken on bike paths? Well, one reason is that it doesn't look like a bike and that's be good enough to get arrested in many districts. But assuming people judge on more than appearances (haha, a joke, I know.), should normal pedal velomobiles also be banned? What about recumbents? What about recumbents with half-fairings? What about recumbents with full fairings? Is is the mere full-fairing that makes it illegal?

Well, assuming that velomobiles would be allowed (assuming they went the proper speed and gave courtesy to other users), a major obstacle would be the non-standard wheel-base that I'd want. And quite properly, I don't think wide wheel-based vehicles should be allowed on standard bike paths (And I definitely don't think gas vehicles should be allowed on paths - it sickened me to see motorcycles riding down a bike path). So what if the back wheel base was retractable as needed, and the wheel base could conform to that of a normal pedaled velomobile? I still don't think it'd go without law enforcement hassles in real life, but it's nice to think that it could theoretically be allowable. Anyways, retractable wheel-bases, FTW! I've never seen that, so it's probably just another dream.

 

[TylerDurden]

FWIW, 'wheel-base' usually refers to the distance of contact patches front to rear, "track" refers to side to side distance.

Here's a looong blog about a leaning velo trike. He added a means to control lean, using cables and a brake.

http://www.adventuresofgreg.com/RocketMain.html

Steering: Sept 9, 2004
steering mod: Nov 28, 2004
lean details: Nov 5, 2004

 

[coln72]

CrMo is not that hard to get a decent weld, I can use a MIG to weld it and produce a strong joint. Its just that it is so damn thin it blows into holes easily. I've also heard of people getting a decent joint by brazing the CrMo, but I do not have any details of this process.

Ever considered Alumium. We have used 16mm Al tubing bent to shape for the main roll bars (head and knee bars) and this was strong enough to survive impacts of 50km/h+ In fact after a quick once over by the officials, and a rear wheel repair the trike was sent back into the race.

 

[swbluto]

Now I'm starting to dream a little bit more here, haha.

I was thinking about solar panels. We all know how they are practically useless for normal ebikes because you have to carry them around and they don't really provide that much power for the power demands that normal ebikes have. But what about an aerodynamic trike that has 4 times less the power demand with relatively substantial roof real-estate available (With the right design of course - with two seats, one in front and one in back, it should be a relatively long roof.))?

I wonder if it might actually be practically possible to run at 30 mph on flat-land with the power of the sun alone during mid-day. I figure it'd take somewhere around 200-300 watts to maintain 30 mph on flat-land, so what are some common power outputs for the flexible solar cells?

I'd guesstimate there'd be about potentially upto 20 to 30 sq. ft. of roofing available.

Anyways, even if only the solar panels helped during pedaling, that'd sure be nice to think you wouldn't even need batteries except for acceleration and up hills. So, in essence, if ridden in city traffic during the day, you might only have to choose batteries based on acceleration needs and capacity for hills. Of course, night riding will need a battery capacity designed around range, but if I limit myself during the night, then maybe not.

For one thing, that would sure increase its likelihood of being the target of thieves. I might have to seriously consider "very serious" forms of security, like possibly an alarm that goes off when the vehicle is significantly moved when the wireless key isn't around and of course a gps tracking system.

 

[swbluto]

Ok, I'm doing some calculations based on this page - http://www.powerfilmsolar.com/products/portable_remote/index.php?cat=pr_foldable.

It appears you could get 60 watts from 18 sq. ft.

Oh, dear, it looks like it wouldn't be practical. However, it does seem like it might possible to get "solar assist", at least. Judging from some quick google numbers, it appears the market prices are about $2-3/watt? Not bad.

I think I'll look up the "best of the best" by searching for "power density". Maybe different manufacturers have substantially different conversion efficiencies (But, of course, the more efficient ones would be more costly)?

According to http://en.wikipedia.org/wiki/Solar_vehicle:

While the sun emits 1370 +/-3.4% watts per square meter of energy, 51% of it actually enters the earth's atmosphere and therefore approximately 700 watts per square meter of clean energy can be obtained.

It seems like 20% if a high-end conversion efficiency for commercially available cells, so if 20 sq. ft. = 1.85 m.^2, it looks like I could convert approximately 700*1.85*.2 = 259 watts at the high end. After a conversion efficiency of 90% (Converting it to a useful voltage), it looks like I could expect a possible high-end watt output of 230 useful watts. Now I just need to find solar cells that give a 20% conversion efficiency! I kind of wonder if those flexible ones even come close...

According to http://en.wikipedia.org/wiki/High-efficiency_solar_cell#High_efficiency_cells, it appears that "Multi-junction silicon"(The hard crystal stuff) has reached 40% in laboratories and I'm guessing somewhere around 30% in practice. It appears the thin film type achieve 18-19% in the lab and I'm going to safely guess somewhere around 11-15% as commercially available. It appears thin film wouldn't be ideal for power density (With limited roof space), but yet it seems integrating the hard crystalline flat panels would be more of a challenge without seriously increasing drag.

 

[John in CR]

I agree, a solar only bike/trike wouldn't be practical unless it spends most of the time sitting in the sun charging your batts. Just look at the vehicles participating in the Solar Challenge to get an idea of solar only vehicles.

I'm not sure the purpose of flame retardant that you brought up regarding my thin plywood/epoxy/glass construction. I don't plan to have any fires aboard, or to drive through any forest fires, so I see nothing but plus side for a non-electrically conductive construction. Plus I'd rather be around burning wood than burning plastic any day.

John

 

[amberwolf]

Regarding the drag on flat silicon panels: Since you need to have a hard cover over them anyway to prevent FOD, if you arrange them in whatever faceted manner you need to approximate the shapes for your aero contours, then complete the contours with curved hard clear covers (lexan, etc), the aero would be much better, perhaps even still ideal depending on how you went about it.

 

[swbluto]

Regarding the drag on flat silicon panels: Since you need to have a hard cover over them anyway to prevent FOD, if you arrange them in whatever faceted manner you need to approximate the shapes for your aero contours, then complete the contours with curved hard clear covers (lexan, etc), the aero would be much better, perhaps even still ideal depending on how you went about it.

Yes, possibly. I must admit I'm a n00b with solar panels, so I'm clueless about how practical it would be. It just doesn't seem like flexible panels are so exciting if they're so much less efficient then crystalline ones, but I guess they have their special applications.

Anyways, regarding the practicality of speed based on previous solar vehicles, here's this: http://www.wired.com/autopia/2009/05/welsh-solar-car-follows-the-sun-at-100-mph/

They apparently already have one that runs at 60 mph, so I think my modest 30 mph demands might be realistically achievable in practice.

 

[John in CR]

They apparently already have one that runs at 60 mph, so I think my modest 30 mph demands might be realistically achievable in practice.

Only with lots of area of panels. The sun contains about 1kw/m2. In full and direct sun a high quality solar panel can operate at slightly over 10% efficiency, so you're looking at roughly 100W output for a square meter of panel area when you have full sun (only 5-6 hours on cloudless days) and the panels face the sun directly. It really only makes practical sense with batteries supplying the motor, and the solar panels helping to extend range and charge the battery pack while parked. As NanoSolar ramps up it's production of thin film PV panels, which will drive PV prices down, then solar as part of our hybrid e-bikes will start to make practical and economic sense.

John

 

[swbluto]

Wow, only 10% efficiency? I thought some commercially available would be more efficient than that. I agree that flexible ones like NanoSolar's are probably around that efficient, but I just spotted this claim from SunPower http://www.ecogeek.org/component/content/article/294. Apparently, a blazing 22%!

But, I'll deduce the amount of power per sq. area so it can be calculated for a given area.

265 ft.^2 per 4000 watts. That's about 15 watts per sq. ft.

So, 20 sq ft. would generate a "300 watt system" (AC rating). Sounds pretty nice! But I wonder if the crystal's inherent fragility would make it impractical to use on a vehicle. It'll have suspension and all but... still. Maybe the sun panel can have its own suspension like a layer of foam.

But I don't think a PV velomobile would be practical in Seattle. Too treesy (Too shaded) and too cloudy too often. I need to move to California or somewhere in the desert to get some ultimate very low running cost solar vehicle going. The ideal conditions would be - very few hills, very sunny most of the time. Sounds like I'm looking to live in a desert town! But, hey, wait... it's hot in the desert, so I'd like some A/C. Oh, shoot, the power needs just went up. Ok, so it needs to be somewhere constantly sunny and relatively devoid of shade but yet a moderate climate that doesn't require A/C. Ok, so somewhere in Southern California...

 

[gerhardt]

Hi Swbluto,
I am designing a Safety Delta E-Trike that may meet some of your requirements. I attached a photo of the chassis. I am currently designing an aerodynamic enclosed body for the trike. The pedals drive a jackshaft with a chain to a Nexus 8 speed hub in the LH rear wheel. There are a total of 168 speeds. The front two speed hub motor is driven by a 35 amp 72 volt controller. The chassis is designed to also accept a gear electric motor driving the RH rear wheel. The width is slightly less than 32 inches so the trike can fit through a 32 inch door. The front lean wheels can be extended out another 12 inches if desired. The lean wheels can be replaced with small skis for snow use. The length is slightly less than 8 feet so it fits in a mini van when the upper roll bar is removed. The ground clearance is six inches and it should operate in snow up to five inches in depth. It has excellent performance and is a lot of fun. I am designing the body with impact side bars and preinflated air bags to eliminate injury at crash speeds up to 35 mph. I am limiting the top speed to 35 mph. I have conducted a roll over test. The roll bar keeps the trike from rotating more than 90 degrees. The trike slides on the side impact bar without injury to the operator. I use a 4 point racing harness to keep the operator in the protection area of the safety cage. The trike has both a 72 volt and 12 volt electrical system. The 12 volt system can be used for the radio, lights, turn signals, air horn and front & rear video cameras.
Don Gerhardt

 

[amberwolf]

It just doesn't seem like flexible panels are so exciting if they're so much less efficient then crystalline ones, but I guess they have their special applications.

One consideration as to which type you'd want on a light vehicle like this is what tradeoff must you make?

--Each panel setup for crystalline silicon types must include backing, reinforcement, support frame, interconnect wires between cells, hard but transparent FOD cover, etc, all of which weigh a lot more than the cells, I'd guess.

--Each panel setup for flexible panels really only needs the panel itself, plus perhaps some transparent thin plastic to keep scratches from damaging the panels. Impacts and such that would shatter the other type shouldn't do much damage to these. That makes them very light.

Is the extra power you would have to use to accelerate and move around the support framework for the silicon panels more, less, or equal to the extra power you will get out of them compared to the flexible ones?

That's one big question you'd have to determine the answer to before picking one or the other.

 

[swbluto]

It just doesn't seem like flexible panels are so exciting if they're so much less efficient then crystalline ones, but I guess they have their special applications.

One consideration as to which type you'd want on a light vehicle like this is what tradeoff must you make?

--Each panel setup for crystalline silicon types must include backing, reinforcement, support frame, interconnect wires between cells, hard but transparent FOD cover, etc, all of which weigh a lot more than the cells, I'd guess.

--Each panel setup for flexible panels really only needs the panel itself, plus perhaps some transparent thin plastic to keep scratches from damaging the panels. Impacts and such that would shatter the other type shouldn't do much damage to these. That makes them very light.

Is the extra power you would have to use to accelerate and move around the support framework for the silicon panels more, less, or equal to the extra power you will get out of them compared to the flexible ones?

That's one big question you'd have to determine the answer to before picking one or the other.

Indeed. It seems there'd be some optimum "golden mean" depending on the context of the driving. If the environment is mostly straight through, flat terrain, little stopping type of riding, then it seems the extra weight wouldn't hurt. Hills, lots of stops, etc., the weight would start to increase the average power demands, possibly significantly.

Anyways, I found this article about a 240 mpg car at http://autos.yahoo.com/auto-shows/frankfurt_auto_show_2009/1106/Volkswagen-L1-Concept;_ylc=X3oDMTE2djM5NjIyBF9TAzI3MTYxNDkEc2VjA2ZwLXRvZGF5BHNsawN2d19jb25jZXB0

It seems to have quite a few of the same principles my idea had in mind. Mainly, extremely aerodynamic (and efficient being a big one), so it seems like this type of design might be something that future may converge to depending on where energy costs go.

 

[morph999]

swbluto, from what I read about the go-one velomobile, if you get one that is very aerodynamic, you can easily go 30 mph just on pedaling.

 

[swbluto]

Just found an interesting article on NanoSolar.

http://www.wired.com/wiredscience/2009/09/nanosolar/

Given the implications, I really hope they succeed! Thin film solar that's 16% efficient and ~1$/watt? Wow, sign me up!

I was drawing the design on paper and it seems that if it was designed like a car (the main body would still be thin for aerodynamics, but there'd be support bars for the solar panels; a 4-wheel system might be optimal if it was designed to tackle snow, although I probably wouldn't get too much snow in a fairly moderate sunny climate that I probably would move to.), the amount of solar real estate would approach 3.3 sq. meters. The standard irradiance seems to be around 1000 watts / m^2 according to this book I was reading yesterday, and at 16% efficiency, it looks like upto 1000*3.3*.16 = 528 watts is possible. Since I think I'd need about 300 watts with this configuration to maintain 35 mph on flat land, it seems like there's a fair bit of room to play with. Also considering a third to half of typical travel time is stuck at a traffic light in the city (depending on your local infrastructure), it looks like it might work out pretty well. (Crystalline might be a tad more efficient, but I don't think it would offset the energy consumption from the increase in weight.) The ideal environment would have moderate temperatures so that energy-intensive air conditioning wouldn't be needed, otherwise, solar doesn't work out well at all unless one does fine without air-conditioning.

 

[John in CR]

Once they get near $1/watt, then we cover the entire vehicle. That can net virtually unlimited range with a smallish battery when the weather cooperates. Also, keep in mind those rating are max ratings and way above real world average.

One consideration is the 85% that is turned into heat. A solar panel is structure to absorb light, not reflect it, so you'll have quite a bit of heat to contend with vs a non-solar where you use light colors and shiny to reflect most of the sun instead of absorb it.

John

 

[swbluto]

Once they get near $1/watt, then we cover the entire vehicle. That can net virtually unlimited range with a smallish battery when the weather cooperates. Also, keep in mind those rating are max ratings and way above real world average.

One consideration is the 85% that is turned into heat. A solar panel is structure to absorb light, not reflect it, so you'll have quite a bit of heat to contend with vs a non-solar where you use light colors and shiny to reflect most of the sun instead of absorb it.

John

It seems the max rating only possibly affected their purported efficiency and their price per watt. If it's just price per watt, then oh well. If it meant transportational service for the next 10-20 years, I think I could possibly accept the price increase. What's an extra thousand or two?

Anyways, the impromptu design I had only would have the solar panels attached to the roof of the vehicle, and the sides would be extended out with support frames for the rest, so hopefully heating wouldn't be too problematic - maybe a transparent thermally conductive material ontop to protect the panels and a thermally insulative cushioning material underneath for the roof.

 

[amberwolf]

Or a partially transmissive film over the panels, to reflect the infrared and UV portions that don't get turned into power anyway.

 

[todayican2]

Not sure if this is the right forum to post to, but I saw this while looking for bodies for a road going trike I am looking to build, looks like it might be about right to turn some of these hot rod tadpoles into something cool (as if they werent cool already)

http://www.blueskydsn.com/kit_aero.html

 

[purplepeopledesign]

I lived in Vancouver most of my life and I have to say that if you are worried designing your vehicle for snow in Seattle (as indicated by your location), you are adding a whole lot of weight and complexity for about 10 days at most every year in which snow might actually stick on the ground. I say, don't worry about it and take the bus or bum a ride.

Now that I live in London, Ontario, there are still only about 20 days each winter in which they haven't yet plowed the roads and sidewalks. And even on those days, I can always grab my FS mountain bike, bleed a little air and go off-roading in the city.

ensen.

 

[jag]

Not sure if this is the right forum to post to, but I saw this while looking for bodies for a road going trike I am looking to build, looks like it might be about right to turn some of these hot rod tadpoles into something cool (as if they werent cool already)

http://www.blueskydsn.com/kit_aero.html

Very cool looking. I wasn't sure if I read the web page right, but it seemed to offer both chassis and canopy pieces in the kit.

Design might be more suited for races than everyday use. Too much side area. Yesterday I eBiked through 50-70km/h winds and it was challenging enough w/o a canopy when the side winds would hit.

Like their extensive .pdf pamphlet suggests, small boat/canoe/kayak building techniques transfer to making these types of vehicles.

Use of Lead-acid in the competition seems a bit stone age. Wonder if it would work to specify a max Wh (say 1000) and let contestants use any chemistry. Or would battery costs spiral out of control?

 

[todayican2]

I may have posted the wrong link, here is one from the same company for pedal power. Looks like a direct fit for a modern tadpole?

http://www.blueskydsn.com/kit_hpv.html

 

[coln72]

Like their extensive .pdf pamphlet suggests, small boat/canoe/kayak building techniques transfer to making these types of vehicles.

Use of Lead-acid in the competition seems a bit stone age. Wonder if it would work to specify a max Wh (say 1000) and let contestants use any chemistry. Or would battery costs spiral out of control?

That is what the organisors of the competition I am preparing a trike for has done I guess. We are allowed different amounts of batteries depending on the type. Up to 100kg of lead acid down to 30kg of lithium with no mains charging.

 

[amberwolf]

http://www.blueskydsn.com/kit_hpv.html

That one is interesting, though they didn't pay much attention when titling the article: "HPV VEHICLE KIT". What do they think the "V" stands for, anyway? Reminds me of the way people say "NIC Card". :lol: