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Moving toward a transportation system that fuels healthy people and a healthy planet.


MAX Update No. 33: Your Roof Ideas Wanted

Lots of the Auto X Prize design guidelines are worth continuing to follow as we develop our 100-mpg DIY car. If you scroll back to Update No. 19: A Roof Over our Heads, you'll see our first shot at compliance with the Auto X Prize’s no-roadsters rule. And if you scroll ahead a couple of posts from there, you'll find Update No. 21: New Motivation for an Enclosed Cabin, which pretty well speaks for itself.

DIY car cabinI've driven a couple thousand miles with that “bikini top” and it's excellent for sun protection and decent for ordinary rain protection, but in serious rain, snow or slush storms, it's no great shakes. It didn't help streamlining either. The bikini top had five of the eight features we want in a top (it was cheap, it was light, it was simple, it was reliable, and it looked kinda cool), but it missed out on two biggies — weather protection and drag reduction, and it only gets a C- in the easy entry category.

I'm confident we can do better, and when I say “we”, I'm including you! If you'll go to the Kinetic Vehicles website and scroll down to the bottom of the page (look for “August 2009” subhead), you'll find some computer generated pix (side, front, top and rear) of the streamlined, aerodynamic body we're currently constructing, with front roll bar and split windshield added in. You have my enthusiastic permission to download those images and doodle up your own cabin ideas.

If you come up with something you think is worth sharing, follow the instructions on the Contact Us page to let me know. I'll write you back and we'll work out a way to transfer it. Use “MAX cabin kv” as your subject when you e-mail me. If you're a Rhino user (our software of choice for 3D imaging and CAM), let me know and I'll send you a Rhino file of MAX to work with. All I ask is you please don't send me any attachments — our system rejects anything with an unexpected attachment and I'll never see it. Actually, I'd rather not get any spam either, but I'm willing to risk it in the pursuit of a better roof.

 


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timothy boles
9/5/2009 8:20:31 PM

Jack I finally got caught up on the updates for MAX. I have been investigating a Locost 7 type vehical for a while now. I have been looking at not only the Lotus 7 and 11, but also the Maserati Birdcage, and Dwarf cars and Legend cars. But using a touring type engine rather than the 'screamer' crotch-rocket engine. I have been contemplating a diesel, but am not that familiar with small diesels. I figure that I would need/want about 50-80 hp in a diesel, and about 125 to 150hp in a gas engine I like the 'Morgan Aero-ish' type body you have rendered up for MAX, and making it into a GT idea. A fast back with the 'Duval' type windshield should help you out a bit. I was thinking along the lines of an 11GT or even a small D-type GT in profile without the deep channels of a pontoon style body I have never heard of Rhino-cad. I am a CAD drafter by trade. I use AutoCAD most of the time but have both Mechanical Desktop, and Inventor on my work computer (and a full metal shop outside that i can't use) Tim Boles


jason hinton
9/4/2009 9:59:34 PM

I vote for leaving the roof off and discarding the windshield. By going with a low profile "speedster" design you will have a much lower frontal area that is key to low drag. To cut down on your drag co-efficient you could make a deck that encloses on side of the cockpit when driving solo. The Lotus 11 is an excellent example of this type of car. Enclosed cars are very difficult to make water tight, even for large automotive companies.


adrianh
9/4/2009 2:53:33 PM

I wish I could draw, but I still have an idea. Not sure if the car ever made it out there but we used to have a car called the Triumph Stag. One of the variants in the roof was called a 'T bar'. I have been wondering for a while if this style could be used between front and rear roll bars to form the frame for either... Now don't laugh! Gull wings in plexi glass to come down to the side of the bodywork or at least form a better frame for a fabric roof with press stud fasteners. The problem always seems to be you have to climb in these cars, so conventional doors will never do. You need the roof to not be there to climb in, the gull wing idea as in the Delorean may solve this using a T bar as the frame for it. The T bar would also have to form the A pillars around the window frame/front roll bar and around the rear roll bar. The back could have two options open/ or plastic rear window. Adrian