[todayican]

Ive built 3 vehicles so far from scratch, and have learned many things from lots and lots of mistakes :-)

There are some "middle paths" that can be taken, like the use of a pre engineered front end, common on ebay most of them follow the design of the ford mustang, just search "mustang ifs"

also, personally, I am a fan of the reverse trike, better aero, lighter and a whole lot easier to register.

there is an active community of scratch builders over at locostusa.com for the not faint of heart as well ;-)

[sunworksco]

Some of the kit-cars out there offer some very lightweight aluminum GM style suspensions and can be converted to custom machined Ducati 1098/GM Siamese hubs for using BST carbon fiber wheels weighing 5lbs. each.The wheels will accept car or motorcycle tires.Lathes are very resonable now , used or new.You can machine some of the parts.For anyone considering building a scratch-built ev,you might look at the reverse-trike car designs.Like the comments here,it qualifies for a motorcycle license (K.I.S.S.) and takes you places and gets you parking spots that cars can't compare with (Diamond lanes).These can be built out of aluminum with minimal fiberglass body panels and as light as 600lbs. (single place) with batteries included.Google up Lotus aluminum chassis bonding/Egot rivets for the chassis fabrication and you will find that you don't even need any welding skills since the strongest chassis is bonded with epoxy and rivets.This technique has made it possible for Lotus to fabricate one-off cars on the cheap.They stretched their Lotus/Elise chassis for the Tesla electric car for battery storage space.Also take a look at the latest in lightweight aluminum panels from www.alulight.com. These aluminum panels make the best battery bulkheads and floor panels.They are nearly crush-proof,float on water light,electro-magnetic radiation shielded,heat resistant and can be bonded to aluminum extrusions.

[TomA]

Wow, sunworksco, that's a lot to take in...

First, what kit car suspension components in aluminum are you referring to? I would like to have a look at them as they may save me having to fab CrMo arms for my vehicle.

Second, my study of the Lotus bonded aluminum chassis indicates this is beyond the home builder. Most of it is extruded, so those bits are out. Then, it is bonded with a cured 200 degree centigrade adhesive process. No oven that size in my house. Also, the rivets go in with a special high speed tool. I could use other rivets, but it is getting pretty tricky and pricey now to do this thing. Lastly, that Alulight foam sheet doesn't seem to be available in the US at any price, and I'm thinking its really expensive wherever its available. Am I missing something here, or is this technology really suitable for a home builder?

Third, my reverse trike single seater vehicle will be far lighter than 600lbs- my target is only 400lbs including batteries. My studies show only composites, (carbon and kevlar cloths matrixed in epoxy over foam cores) with or without small chromoly subframes, are the way for me to get there and still be able to build it myself without going broke on components or tools. Again, am I missing something? Is there a better way?

And please do show me those aluminum kit car suspension arms. That will be really cool.

Thanks,

TomA

[Duncan]

Hi Tom

Warning Composites and aluminium do not go together well

Gluing aluminium is the sort of thing that gives engineers grey hairs
It is possible but it uses processes that are not home friendly

If you decide to use aluminium inserts in your carbon/glass fiber you need to get them properly treated or the joint will fail due to humidity after a short time (two years?)


Other comment,
It is nearly impossible to make carbon fiber parts as strong and light as S glass using a wet lay-up

If you are using pre-pregs ignore this comment

[sunworksco]

Alcoa Aluminum has spent $millions$ on developing this bonding method and it has been proven in the Lotus chassis.Since the aluminum epoxy fabrication was published , 3M has developed 2-part epoxies that do not need oven-curing.You also have the option to use a powder-coating oven.These are usually made from large ship containers.The epoxy is for shear strength ,only.The mating surfaces do not need anodising as well.The mating surfaces can be acid wash prepped,cleaned in distilled water,dried then epoxied together.Yes , Lotus has custom aluminum extrusions but anyone can use standard square tubing and aluminum sheet.The Ejot rivets can be driven into place with a simple air or electric drill.Lotus has developed an assembly line robot for this.The chassis can be built with a 10,000lb. torsional rigidity.The fiberglass body would be non-stressed.Alulight panels are availible in the US but you can use regular aluminum sheet material.Alulight 4'x8'x1/4" panel with 1mm aluminum sheets on each side of the aluminum foam is around $800.00.It is pricey but coming down in price.I would recommened using this for the battery bulkhead and the main floor of the chassis.It is super strong and heat resistant.I'm a home builder and very confident that I will be using this technology with ease.You can still keep your target weight with this technology by using the aluminum chassis and fiberglass for the body.
The suspension shown here can be modified and down-sized for any size vehicle.

[TomA]

Thanks for the info. Looks like these pictures came from Cutting Edge Replicas. Nice, and probably pricey. I like the bellcrank low-profile front end. Asking these guys to fab up something custom for me is, no doubt, too expensive.

I appreciate your preference for the bonded aluminum. Its an interesting material and has the gee-whiz factor to go with the high cost. Its just too exotic for my skills, budget and desire. When you start fabbing up your monocoque, please post pics for us to follow along. Sounds like a great project!

And Duncan, yes, I'm aware of the hard point problem with composites. My brother-in-law has a LongEZ and a bunch of RC helicopters, and is a good resource for composite aircraft construction techniques. All my inserts would have been alondine coated, but I'm still not happy about them. I'm also aware of the electrolysis problem between CrMo steels and Al alloys, and for that reason I will most likely delete the aluminum altogether from the chassis.

At this point, I'm playing a weight, space and packaging game. I'm using CrMo and composite because both are relatively cheap and very workable at home. Low weight is the trickiest part of the game. Low drag is almost completely controllable by shapes and surfaces, but no less tricky, really. Its a four dimensional (the fourth being cost) puzzle that would be familiar to anyone scratchbuilding a vehicle of any kind.

Fun, yes? I'll keep y'all posted...

TomA

[sunworksco]

Type III anodising will not corrode in fiberglass.The price of aluminum has hit the market bottom and is very affordable now.The nice thing about Cutting Edge is their suspension is fully engineered.
I will post images when the chassis is built.
Thanks for the exchange of ideas.I think your build with aeronautical design is the best way to go.I really like the Aptera trike-car.

[TomA]

Originally Posted by sunworksco

Type III anodising will not corrode in fiberglass.

Hard anodizing? Wow...

That's what I love about you, sunworksco. Every time there's an obstacle in the path, you have the most exotic, difficult and expensive answer for it. If you are taking that approach to your vehicle, when finished it will be worthy of any OEM, and truly a thing to behold.

One thing I've learned about "fully engineered" off-the-shelf hot rod products, though: they usually aren't. Just because someone can CAD/CAM billet parts doesn't mean they are properly tested, durable or even soundly designed. When I see the track mule Cutting Edge Replicas uses to wring out these suspension bits, and the pile of previous designs and broken bits, then I'll believe it.

Even small volume OEMs have tons of downstream design engineering issues, many of which never get corrected- how about the rear wheel bearings on the Subaru SVX, for one small example: undersized, they last only about 10k miles, and there was never an upgraded design in many years of production.

That's kind of what is so awe-inspiring about your thinking. Everything you suggest, from bonding aluminum panels to hard anodizing parts, is a slow and expensive trip up a steep learning curve to master an advanced construction technique and material. That's really something to see for a guy like me- I'm looking for the easiest, cheapest way to get everything done within my performance envelope and tight budget. That doesn't make everything easy or cheap, but it does mean I don't think about solutions the same way you do.

Happy New Year, man, and stay in the deep end of the pool. Its nice to know you're there...

TomA

[sunworksco]

Hi Tom,
Your RT build sounds like a very good one.Will it be fwd or rwd?Is the wheelbase longer?
I will try to attach the Lotus aluminum epoxy bonding sheet.
It is and old article and the bonding is much simplified now.

[Matthijs]

Aerodynamics: a weighty matter Allert Jacobs added 88 lbs / 40 kg worth of aerodynamic modifications to his bike. He admits he didn’t try particularly hard to fabricate light parts, so his Honda now weighs 43% more (!) than it did when he bought it.People who aren’t familiar with the subject of Aerodynamics often predict (mistakenly) that the extra weight of aero mods will hurt fuel economy more than reducing drag will help.
Obviously that’s not the case here. Aerodynamic improvements trump weight.
The exception may be for vehicles that spend the majority of their time in heavily congested urban traffic at very low average speeds. Clearly that’s not Allert’s situation. In fact he figures the added weight on the Honda is a benefit because “it will make it more stable in side wind situations.”


http://ecomodder.com/blog/diy-aero-f...cycle-214-mpg/