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Hi John
You probably already know this but if you have a "streamlined" body the drag is caused by skin friction and is proportional to "wetted" area so it makes sense to make the vehicle as small as possible

As far as I am aware we don't need a windscreen and wipers here in NZ so long as we can either see over the screen or somehow move it out of the way when its raining
Like the old folding screens

That could give you an option to achieve the low drag when its dry
 

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I'm very intrigued by the whole monocoque construction thing now. :) I'm toying with the idea of a monocoque street rod, to see just how light I can get it. What are you guys using to determine and develop the technical characteristics of the shell? How are you determining the what type of loading it can support, how the stress from the suspension attachment points transfers into the vehicle? What type of construction materials are you planning? What are the construction methods and materials for your suspension attachment points?

Just curious about how you're going about building. My new design software can do most of these analysis, but I haven't had time to do anything but install it so far. It reportedly has a moderately steep learning curve. Maybe a project like this will give me a way to explore some of its features.
 

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I wish you would 'go for it' Todd, you could come up with something really fluid and 'sexy' looking.

An off the shelf monocoque trike shell kit would be fantastic.

You could work on the basis of a series of equally spaced 'rings' that form the cross sectional shapes of the monocoque in a sandwich contruction from front to back.
Each ring could be braced to it's neighbour with a series of thin struts to form a sort of wire frame. That can then be filled with foam and then glassed over.
Motor and suspension mounts could be built into the wireframe and secured to the section rings and braced across to spread the load.

You could market it as a flat pack.:D
 

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I wish you would 'go for it' Todd, you could come up with something really fluid and 'sexy' looking...

An off the shelf monocoque trike shell kit would be fantastic...You could market it as a flat pack.:D
Geez Woody, you went straight to production! :eek::D I am just toying with the idea of a one-off concept, as an exploration into different areas of design, and of course for marketing my design services. The two issues I have with production are composites and liability.

While I love the potential of composites, I can't stomach the thought of doing anything more than an occasional product. I guess I spent too many years scratching my skin off to enjoy it anymore. Sub-contracting the shell construction sounds expensive, and EV enthusiasts are normally very cost senstive.

Product liability for a composite, monocoque, road-going, vehicle kit sounds like a recipe for lawsuits. Guy buys, builds, and enjoys his trike; then gets T-boned by a runaway Geo Metro, and doesn't make it. The wife decides to sue me too, even though the Metro driver was legally blind and didn't see the light turn red, because she was always terrified of him being out there in that little plastic bubble! A conventional chassis I can verify all day long, from 100+ years of them being used. A "plastic eggshell" (view that would likely be painted to a jury)? :)

As usual though, you're thinking how I'm thinking as far as construction is concerned. We should discuss this idea further. I've already begun collecting parts... ;) Not sure whether to start yet another thread, or discuss in PM?

Sorry for the hi-jack Darxus. I really am interested in your plans for structural integrity, attachment points, etc; and figured the shared knowledge of others considering/experienced in monocoques could help everyone.

Without going into too much detail about my own plans, I am thinking about a couple/few wood stringers that would run longitudinally from the front suspension points to the rear. Wood because it has some inherent strength, and can be easily machined to accept metal attachment points. Thoughtfully spaced ribs, as Woody referred to, along the length and 'glass it all in with S2 cloth; and maybe some carbon fiber and/or Kevlar reinforcement in key areas.

I think I am going to work from the outside in though. Basically build a thin exterior shell, then incorporate all the structural components in from the bottom and openings. So the ribs and stringers can be cut and shaped to fit the shell. The rib cores would be foam.
 

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You could work on the basis of a series of equally spaced 'rings' that form the cross sectional shapes of the monocoque in a sandwich contruction from front to back.
In fuselage-speak these rings are called formers. They are located at and define specific cross sections of the shape, (stations,) and are then connected by stringers (boat speak) or longerons (aircraft-speak.) This is in fact how most boats and airframes were built for centuries. Still are, in many cases. Monocoque construction is different...

My construction technique will be S2 glass fiber over styrofoam, (Extruded Polystyrene or EPS,) not the beer-cooler pearl stuff, but the blue or pink 2" thick panels. It cuts nicely with a hot wire, is easily glued and epoxied, and relatively cheap.

Urethane foam is nicer to sand and finish, but its toxic when heated with the hot wire, and it powders under vibration. Its more expensive, so I'm going with the EPS.

An ideal build would be a single molded piece of EPS covered in composite (epoxy and glass) matrix. This isn't practical for anything short of volume production, so I'm going to piece together the monocoque with the slabs, sand to shape, glass the outer shape completely enclosed, and then cut out the access panels and holes for wheels, cockpit, etc. I am still working out whether to employ steel subframes for the suspension pickups, or just hard points on an all-composite chassis. I'm not an engineer, so it isn't an easy problem for me. Of course, it wouldn't be all that much easier for an engineer, either.

I will probably have a mix of subframe and steel hard point suspension attachment, with the shell being primarily S2 glass and Kevlar reinforcement as necessary. The problem with composite isn't strength, its the failure mode- catastrophic (shatter) when it goes. That's why I want the steel subframes. Wood is an excellent strength reinforcement material for composites. The thin longitudinal wood stringer is what gives a traditional surfboard its strength and resistance to shattering.

Anyway, the slightly shorter answer is that calculating strengths and loads for these materials is aerospace design engineering, and well beyond even accomplished car builders. That's why composite structures tend to be so heavy, because the designer isn't Burt Rutan, and he's being conservative in the absence of any real knowledge of what the material needs are for the strength required. That's one reason why kit car bodies weigh up to 500lbs, when they could actually be under 100lbs if they were as efficient as composite aircraft in using the same materials. I'm stuck in this same box, and will be using steel and significantly more composite mass than I probably need because I just can't do the math to divine the lowest possible weight for my purposes. Not a big deal, but another real downside of using an exotic material.

Anyway, back to this former-stringer construction. I wouldn't recommend it if the idea is simply to make up the core of a stressed-skin monocoque outer shell. Making the stations and ribs of different materials, and filling in the gaps with 2-part or spray foam introduces a lot of variables into the material. I can't imagine that being particularly easy, either.

It would be much better to just use the software to make the whole thing up out of formers cut from 2" sheet. They could be stacked longitudinally and registered on a temporary (or permanent) keel fixture of some kind, sanded smooth, and then glassed into one solid thing. The interior shapes and contours of the shell (basically, the entire composite hull) can also be designed into the 2" body section former patterns, so that the complete monocoque would be built up out of the same material all at once in 2" slices. Pretty straightforward technique, really.

In fact, there's an interesting business opportunity for someone who can produce a stack of these former patterns for such a design. With just a plotter, you could print the stations out full size (a 13' long trike like mine would need about 100 of them, and none would require bigger than 42"x60" paper,) that the customer would adhere directly onto 2" foam to hot wire out the station formers. Better yet, I would glue the former patterns to Masonite and cut that out to make a set of hot wire cutting templates that would produce tapered 2" near-net shaped body sections when a slab of foam was cut between 2 of the templates. A ton of hot wiring, some alignment, a little sanding, and you would be done. Extremely cool.

The set of templates could be rented out, or used to start a small production run of bodies. I can't think of a simpler or more elegant way to get an envelope body built up in a garage with ordinary tools and skills, or a better way to make more than one...

If anyone wants to pursue that with me, let me know. I have a design I'm working on, but I'm CAD-illiterate. I'm also a very good businessman with multiple start-up experience, a serious hot rodder, and I'm ready to work on this. If not, do it yourself anyway, make it work, and offer it as a service. I will be one of your first customers for my design if you are ready to proceed when I start building this winter. So there's the offer- build a capability and a business (and at least one really, really cool electric hot rod for yourself) with me, or do it all yourself and call me when you are ready to sell your fabrication template service product.

Just an idea...

TomA
 

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Discussion Starter · #27 ·
I'm feeling demotivated by the cost of batteries.

I need better kilowatt hour battery need estimation for my commute.
I want to be able to get to work and back, 35 miles each way, part of which is 65mph, with some reasonable headroom. That's where I came up with a 100 mile range.

I worked out that I need 16,000 watt hours, which works out to about $6,000 in Thunder Sky batteries. I do believe that was a very pessimistic estimate, and that it's quite possible half as much would do it. I based that calculation on this car's efficiency:
http://www.evalbum.com/3202

And it probably is reasonable to expect to manage half the curb weight and a third of the frontal surface area. Not to mention entirely laminar vs. not.

The TIG welder I'm going to need to buy for this will probably be at least $2,600 (Miller Dynasty 200 SD - interested in recommendations). And I still haven't gotten an answer better than "It could be $3,500" on windows, probably ten times what I could make it for, just as safe, without the requirement for the little numbers etched on.


I'm hoping to get all my old window fans and some cardboard together to do the input end of the wind tunnel tonight. And based on the results of that, pick up hard board to do an 8'x2'x2' tunnel. Then make a drag scale out of some heavy wire, a protractor, and a small weight of some kind. And get some heavy paper to create 3D models with tape.
 

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...I'm not an engineer, so it isn't an easy problem for me. Of course, it wouldn't be all that much easier for an engineer, either...
...I have a design I'm working on, but I'm CAD-illiterate...
I am on the CAD side of all this. My two primary business associates are also (Ph.D) engineers, so it's more a question of whether or not it's feasible to put the time/money into it for me. The beauty of doing this stuff in the 21st century is the software does most of the work. My software can determine where the major stress would be, where it will fail, etc. But again, it takes time to accurately model stuff for computer analysis...

...I'm also a very good businessman with multiple start-up experience, a serious hot rodder, and I'm ready to work on this...
Just an idea...
It sparks my interest, but I have concerns about liability and ROI.
 

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I'm feeling demotivated by the cost of batteries...
I feel your pain. The cost of building an EV is what made me decide to build a toy, instead of daily transportation. Competition is helping but this is still a very small scale market, so prices can only drop so far, so fast, without a substantial increase in demand.

I'm not trying to dissuade you from a dream, but have you considered a conversion or less-intensive build for your commute and working on the monocoque trike over time? Other than that, I would recommend finding ways to generate additional income so you can purchase whatever it takes to realize this dream (assuming you're not loaded :D).
 

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It sparks my interest, but I have concerns about liability and ROI.
I'm not talking about selling the vehicle, per se, I'm talking primarily about the design consulting product that offers to produce body construction templates for composite monocoque builders (of anything, really...)

In either case, "liability" is a question of talking it over with an insurance agent and buying a policy. Everyone gets wrapped around this axle, and it is painfully simple. If you make a good product, you probably don't need liability insurance for the reason you might think- your liability. The actual reason you need liability insurance is that it provides a defense should you be sued. That is critically important. You don't want to have to hire and pay an attorney or defend your company or its practices. You need to be able to call your insurance company and fax them the summons, and be done with it until your participation in defending the claim is required. You therefore must have liability insurance to be in business, at least with me, anyway. Its just a cost of doing business, and a pretty modest one in my experience.

ROI is a different story. That term, strictly applied to a new venture of any kind, should really stop you from lifting a finger. If you need a monetary ROI then you have to invest in vehicles reasonably likely to produce a cash return, like property, equities and financial instruments. New businesses have a perfectly terrible track record of returning investment, and should not be started simply to make money. I'm not being smug, or overstating it. If the value you have to put into a new venture can't be risked, then don't do it.

You, or anyone, must embark on a project like this because you want to, you're able to, and achieving it would give you a cool new product that either isn't available, or solves a problem in a cool new way. What's the market for it; what are its features, price points, and how do you address the universe of people who might buy it? Those are hard questions to answer, particularly with a new service in a new technology. That's what I'm good at, but something like this isn't going to be a money-maker unless it works for the customer and can be delivered economically. Unfortunately, unless you try it you can't know whether that will be the case. Its kind of a chicken and egg problem. If you don't build it, no one will come. The risk-reward equation starts with the risk.

But let's look at ROI a little more broadly than a banker would. If the investment you're looking to see returned is really just your time, then you can look at the return beyond immediate monetary gain to see if it works for you. The fact that the endeavor is something you are interested in that produces something really cool may make project worth doing for those reasons alone. In other words, it might be a very good use of your time even without clear future profits. The project may also very likely create a value all its own to your future business- like getting you into a community, being a calling card for you, or opening other doors down the road. Those can be very substantial returns. To be sure: if you have to be sure your time investment will be returned with a certain amount of money in a given time frame, then don't pursue the project. Of course, that's how OEMs and public companies decide to do or not to do things, (and why so little of the world's true innovation is attributable to them.)

Anyway, this is pretty far off-topic, and I may well go start another one about being in business doing something that you love and changing the world, but I'm done talking about it here now. Follow up with me privately if and when you'd like to talk more about it.

TomA
 

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Discussion Starter · #31 ·
...have you considered a conversion or less-intensive build...
Thanks, I needed that.

My first several thoughts were "but anything else would require more power."

Then I remembered lead acid.

And the same watt hours in Trojan T-105s is $1,700, and only about 3.6'x1.8'x0.6'.

Still hoping to start work on the wind tunnel tonight.
 

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Thanks, I needed that.

My first several thoughts were "but anything else would require more power."

Then I remembered lead acid.

And the same watt hours in Trojan T-105s is $1,700, and only about 3.6'x1.8'x0.6'.

Still hoping to start work on the wind tunnel tonight.
Did you do any mock-ups, even living room floor leaning against the sofa type, to see if the seating position was okay for you? Maybe with a little cutie behind you? :) Just curious about how different people can tolerate/appreciate different driving conditions. Since you like the crouched race bike position like me, I am interested to know if you like the extreme recumbent position in your model as well.

I don't remember if I mentioned it - sweet bike!

Other options might require more power, but I figured the reduced cost to get them on the road may make it worth it. I usually try to turn over every stone to see how my plans look in comparison, so that's just a thought from an obsessive perfectionist. It all comes down to what your real goals are, and what best realizes them.

Any thoughts on what specific construction method you plan to use?
 

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I worked out that I need 16,000 watt hours, which works out to about $6,000 in Thunder Sky batteries. I do believe that was a very pessimistic estimate, and that it's quite possible half as much would do it. I based that calculation on this car's efficiency:
http://www.evalbum.com/3202

And it probably is reasonable to expect to manage half the curb weight and a third of the frontal surface area. Not to mention entirely laminar vs. not.
Virtually everything that affects the efficiency of your vehicle is proportional to either its weight or aero drag. If you could get the aero drag down to 1/3 and the weight down to 1/3 you would need 1/3 the kWh and kW for similar performance and range as a rule of thumb. That would certainly drop the battery bill and battery weight by a bit.
 

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Discussion Starter · #34 ·
Did you do any mock-ups, even living room floor leaning against the sofa type, to see if the seating position was okay for you? Maybe with a little cutie behind you? :)
Yup.

Darxus: How would you feel about being in this car with me? Should I not bother to try to fit a passenger?
Zephlett: I don't see why I wouldn't
Zephlett: I would ride your blackbird with you.
Zephlett: this doesn't seem too different.
Darxus: That's basically what I was thinking.

Just curious about how different people can tolerate/appreciate different driving conditions. Since you like the crouched race bike position like me, I am interested to know if you like the extreme recumbent position in your model as well.
From what I know so far, I really like it.

I don't remember if I mentioned it - sweet bike!
Thanks. I do love my toys.

Other options might require more power, but I figured the reduced cost to get them on the road may make it worth it. I usually try to turn over every stone to see how my plans look in comparison, so that's just a thought from an obsessive perfectionist. It all comes down to what your real goals are, and what best realizes them.
Yeah, but for "more power" I was still thinking lithium. Which would increase cost.

Any thoughts on what specific construction method you plan to use?
English wheel (for body shaping) and TIG welding.

Nice and simple :p
 

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...From what I know so far, I really like it...
Cool. :)

...English wheel (for body shaping) and TIG welding.

Nice and simple :p
I would love to have all aluminum bodies on my street rods, but don't have the patience. I could get through side one, but duplicating it on side two would be pure torture (perfectionist). I would just have them made but a full race powertrain is more important to me right now. I was quoted around $50K to duplicate the parts I have on the truck now. Maybe you should go into business doing it, if you turn out to be pretty good with that wheel and welder. ;)
 

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Discussion Starter · #36 ·
If you are serious about low drag you need to look at the solar racers
I was briefly excited about this idea, but it turns out they're doing the same thing I am (dual wishbones). They're just taking advantage of the necessary dimensions of the solar panels. For this design it would entirely involve adding frontal surface area. So I think wrapping all the suspension rods in little airfoils is probably the best option. And what, it turns out, F1s are doing.

I have no frontal surface area to move around. It's currently basically just the humans, in an already silly position, and the wheels.

If you have a shape that the flow doesn't separate from (stream-lined) then the old CD x area no longer applies
Awesome. Do you know how far you can maintain laminar flow of air according to Reynolds?

How long were you allowing for your commute?
The HPV record is now over 50mph - normal bikes its about 35mph
It's about an hour each way in my Accord. I'd rather not increase it much.

light weight (50lbs) low power 50 - 150 watts
pedal + electric
or
200+ lbs, 400+ watts light weight electric+
or
Mini Car
1000+ lbs, 30+Kw
Yup, I was actually thinking motorized bicycle similar to the land speed record bikes for a while. Then I figured if I'm adding a motor, I might as well add a back seat, then....
 

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Geez Woody, you went straight to production! :eek::D

As usual though, you're thinking how I'm thinking as far as construction is concerned. We should discuss this idea further. I've already begun collecting parts... ;) Not sure whether to start yet another thread, or discuss in PM?
In fact, there's an interesting business opportunity for someone who can produce a stack of these former patterns for such a design.

If anyone wants to pursue that with me, let me know.

I will be one of your first customers for my design if you are ready to proceed when I start building this winter. So there's the offer- build a capability and a business (and at least one really, really cool electric hot rod for yourself) with me, or do it all yourself and call me when you are ready to sell your fabrication template service product.

Just an idea...

TomA
I was only thinking out loud and look what it started!:D


I keep looking at reverse trike designs and thinking of getting another project on the move too. I have the back wheel and drive, just need to build forwards from there.;)

The light weight option is really the tempting aspect along side the look. I only want a single seater so should be even easier to build, no 'cutie' or 'honey' to worry about.

One of my students reminded me of another overdue trike.
Presenting a seminar on 70's furniture design he spoke of 70's futuristic and space age products and ideas and showed an image of the Aptera. I had to stop him and mention that the Aptera happened some 30 years after the period he was supposed to be presenting on.:D
 

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Discussion Starter · #39 ·
The light weight option is really the tempting aspect along side the look. I only want a single seater so should be even easier to build, no 'cutie' or 'honey' to worry about.
Nng. Yeah. I was playing with a single seater model last night (in my desperation to reduce battery costs). Seating position = laying completely flat except with the head propped up. Batteries moved to pods on each side with air in between to reduce the distance air gets displaced.
 

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I'm very intrigued by the whole monocoque construction thing now. :) I'm toying with the idea of a monocoque street rod, to see just how light I can get it. What are you guys using to determine and develop the technical characteristics of the shell? How are you determining the what type of loading it can support, how the stress from the suspension attachment points transfers into the vehicle? What type of construction materials are you planning? What are the construction methods and materials for your suspension attachment points?

Just curious about how you're going about building. My new design software can do most of these analysis, but I haven't had time to do anything but install it so far. It reportedly has a moderately steep learning curve. Maybe a project like this will give me a way to explore some of its features.
I'm using www.alulight.com all-aluminum foam panels.
The military is using this material in vehicles for strength and weight savings.It can be welded or epoxied together with aluminum extrusions.
The slab-sided trike is my choice.
I'm using Palatov independent suspension with front-wheel-drive.The hubs/wheels,brakes will be Ducati 1098 design.The rear suspension is Ducati 1098,too.:D
Regards,
John
 

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