New Car Project

[treddie]

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Title: Rest Stop

Will probably do post work to get the drop shadow to look like it's not pasted in. Plus extra cooking time to get better noise reduction.

[ROUBAL]

I have got a question : How do you enter into this car ? Doors look classical, but the glass bubble has no cut out. Do the doors lift with bubble ? That's not obvious.

[treddie]

Roubal,

The doors and front portion of the bubble lift up as a single unit. I decided this was fine for a cool concept look, but it is not very practical...or safe. The height that the assembly has to lift so you can comfortably get inside, is too tall for a standard garage ceiling. Safety wise, I played around with different lift geometries and settled on the only really practical approach without resorting to telescoping hydraulics. I settled on a compact arm unit (forearm, elbow, upper arm) on each side that folds down into the rockers. In order to stay away from synchronized motors (qty 3 each side), I went with a single motor each side with a multiple chain drive inside the arms that ensure the doors/canopy lift up without tilting forward or backward. It is a disaster waiting to happen. I solved one problem in that when the whole thing completes its lift, the arms go over-center, so that if a chain breaks, the arms will settle against a hard stop rather than collapse back down again. But if the break occurred during lifting or lowering, then only one of the two arms would be supporting the entire load...a risky proposition. The other failure mode would be if one of the two pins on either side of the doors/canopy shear, then similarly, the entire load is concentrated on the single other pin. If THAT one breaks, then the whole thing rotates down like a bizarre guillotine and that's really bad.

[treddie]

Somewhat grainy image still. Will let it render longer before I post it as a final:

[treddie]

Damn! Just saw that I messed up the map on the doors. Have to restart the render form scratch.

[ROUBAL]

Thanks for the detailed explanations. I would not try to open it a windy day !

A long time ago, a friend of mine, owner of a 2Cv Citroën opened a door on the side of the road with strong wind in front... the door flew at least 20 meters backward in a field !

[treddie]

Lol! Not good.

Come to think of it, the 2Cv looks like it would blow away as a WHOLE in a strong wind.

[treddie]

Here is an interesting entry/exit option:

I would probably have to lift my canopy from the front.

[ROUBAL]

On the car above, link the seat to the canopy, and if you open it at sufficient speed, you get an ejection seat whithout cartridge !

It is a real challenge to mix a very simple/pure design with efficient and safe technology !

From my own point of view (I spent 24 years as a technician in the French air force, and I saw many airplanes), the canopy could be unlocked by lifting up few centimeters, and then slide forward on two hidden rails partially supported by the doors when they are closed. When the canopy is in open position, the doors could open as usual doors do. Using sliding supports in horizontal U shapes could avoid visible rails on the front of the car. The canopy would slide horizontally from A to C.

As an alternative solution, hidden arms could act as a pantograph and move the canopy from A to B and C in a rotating motion while keeping the thing horizontal.

Mechanical constraints would be low, and the system rather simple, and safe in any weather.

What do you think ? Maybe you already investigated in this way.

[treddie]

Hadn't thought of those. Those are really cool ideas. The first one keeps the canopy nice and low, but interferes with the hood; you couldn't necessarily leave the door open when working under the hood, since the rails would have to be in the door. But also, the canopy sides are not straight. They're curved. The second one interferes as well but not as bad, because the canopy would not have to move as far forward as the first option.

So I played around with your ideas and the easiest given the shape of the canopy sides was #2. For Option #1, and because of the curved sides of the canopy, it seemed a rack and pinion mechanism was the best idea, but the distance between the gears on the sides of the car would be changing constantly, so the canopy would have to have some sort of sliding mechanism wide enough over each gear so that they could get closer and farther away from each other. Also, the gears would have to rotate laterally to follow the curve of the doors. I couldn't find a way to hide that whole thing since it has to be too wide.

So for Option #2 I played with a sort of yoke mechanism that followed the curve of the bottom edges of the canopy. That could hide easily inside the tops of the doors, but then I'm back to a stabilizing mechanism to keep the canopy horizontal as it moves. That would either be two synchronized motors on both sides of the car, or another chain drive mechanism that would have to be inside the curved yoke arms. So the two-motor solution seems the only option in that respect.

But if the canopy simply rotated upward, then the second motors would not be necessary. So then I thought, well, shoot, all I need then is basically a front hinge. So if I nix the idea of lifting the doors and canopy as one unit, then I COULD just hinge the canopy at the very front, with the mechanism hidden by a cover in the front of the dash that lifts up with the canopy.