Creating a bubble top for a kit car, legal? and my aero car design.

[cRiPpLe_rOoStEr]

Originally Posted by ecomodded

If the bubble was placed over a convertible I bet it would not need to be inspected.

That makes sense, but you never know what goes thru the mind of the bureaucrats at a DMV

[thewindkeeper]

I saw his activity, but the thread was also 4 months dead so I took a chance on something I was interested in...

the reasons for a bubble top are many, the reasons against are few, we should start with the reasons against:

-the interior gets hot
-there is often compromise to structural rigidity

This doesn't explain why black cars and convertibles are so popular...why all the hate?

it doesnt have to be a hemispherical bubble from the jetsons it will conform to any mold (I'm talking about plastic at this point)


the advantages are that the world is at your wheel, you don't have to deal with the wind and weather, you dont need a rear view mirror or side mirrors (depending on vehicle geometry) it looks unique, potentially avoid glass which is fragile and very incompatible with many designs...I could go on. I was actually hoping to do a more advanced take with a laminated composite straight sections that have a scaffold and fit together like a compound eye. material with active dimming layers built in, this avoids undue lighting, adds some insulation and minimizes the greenhouse effect to some degree but thats sci fi at this point, I'd be happy if I could just start with the basics of how they are formed, I have heard that they are blown and that they are vacuum formed... I would guess the latter but I doubt both are true, and if we can get to the bottom of what is permissible on the road, all the better.

[NachtRitter]

Here is some info on making a blown fairing for a bicycle... should give you an idea: The Recumbent Bicycle and Human Powered Vehicle Information Center. Good luck, and be sure to check with the AZ DMV before you put too much time/effort into it.

[whatmaycome14]

I too have had the same thoughts and have resigned to the fact that in order to be road legal, I'll most likely have to source a windshield from a (cheap?) production car and build my ideal body shape around that. Honestly, it shouldn't be that bad considering that the windshield from an older car is fairly inexpensive.

[thewindkeeper]

In the orignal post, I think he was talking about floated curved glass, this is used in telescope lenses and is usually purchased in small quantity, for an entire vehicle I feel it would be astronomically expensive and heavy. plexiglass or polycarbonate is lighter and has the advantage of being more easily formed. it has drawbacks in that it propagates cracks (the ones that look like spiderwebs) this is called crazing. and breaks down and browns in the UV of the sun and is extremely sensitive to being attacked by solvents such as acetone. I feel this can be gotten around by laminating it between tougher plastics or even doing a different configuration using a sandwich of glass and making the net shape out of a soccer ball type pattern. this may have a few interesting properties but in all likelyhood is a nightmare of complexity and then when you have your magnificent bubble top..how do you roll down the windows...open the doors/roof etc... it definitely comes with its own set of problems, legality though, I have seen cars that have such windows and apart from anecdotes, I have yet to see that this is actually illegal. but then again, I've never had a custom build need road certification. what about the aero-civic guy? isn't he on here? I know he used plexiglass for most of his modification

[ecomodded]

How about pouring a Acrylic bubble top around cars current windshield, make the mold on the car pour it in place to exact size , then remove the mold from the interior of the car.

Although I think it It would be easier to add some curved glass to a fiberglass bubble shaped top attached to the current windshield.

[freebeard]

If an artist didn't struggle with his materials, it wouldn't be art.

Have some inspiration:


If the air wasn't parched and dry that thing would be fogged up. Think about humidity as much as heat.

I was actually hoping to do a more advanced take with a laminated composite straight sections that have a scaffold and fit together like a compound eye. material with active dimming layers built in...

I'd be happy if I could just start with the basics of how they are formed, I have heard that they are blown and that they are vacuum formed..

[approximately] Hemispherical bubbles are blown. Formed bubbles are vacuum drawn. My folks had a desktop device that would form sheets about as thick as blister packaging. It's a very simple process, a hinged door that swings from the heat side to the vacuum side. The complication is that the form needs to be *optically perfect*, one shot, no do-overs.

Insofar as the faceting: I have a design for a motor home that uses flat glazing. It looks like this:


One development I noticed lately is that Bruce Meyers has updated the Manx.


Notice the hidden wipers. You could do worse than start with a Kickout SS hood and windshield frame and a Superbeetle windshield and just fill in the rest of your car behind it. With a bullet-proof transparent roll cage.

Originally Posted by thewindkeeper

...net shape out of a soccer ball type pattern. this may have a few interesting properties but in all likelyhood is a nightmare of complexity...

Actually—mathematically defineable to any desired precision.
http://www.google.com/search?q=geodesic+chord+factors

[Xist]

I remember Frank Lee talking about his experience with canopies, how they seemed like great ideas, but for several very strong reasons, they were not, not at all. I tried to find the post, but "Frank Lee canopy" did not get me very far.

[thewindkeeper]

that's a cool link on the geodesic chord formula's. I'll definitely check that out after work. I meant from a fabrication standpoint, firstly, noone is out giving away the adhesives and construction techniques for bullet proof laminated glass/polycarbonate forms. (I'm very probably wrong on this...some neo-libertarian nutjobs are incredibly smart and motivated when it comes to anything that has to do with guns). then you have to add an active layer as in a photochromic film. this too is easy on its own but the wiring for this fits in the chord members on the lattice between the panes...etc. I want to do it but I still have nightmares about it. I think a monithic or 3 piece dome would be a more practical first attempt.
(I wanted to go further by making each pane programmable so you could have localized dimming..but again, It's just dreaming until I get it right with a single cell or a small segment of the panes.

[user removed]

Windshield for a 3 wheeled motorcycle, fairly easy, reasonably cheap. Bubble top for a car passing DOT standards with laminated glass with plastic layer between the two layers, custom made.

Seriously expensive.

Find a glass that already exists and build around it, maybe more than one and it has to be a windshield, different DOT regs for side and rear glass.

regards
Mech