Spaceship-like car to hit U.S. roads

[jason1973tl]

Originally Posted by XJguy

The problem with this reasoning is that the largest of elephants weighs in at 8.25 tons. A collision into a tree as slow was 25mph an average car experiences 48.4 tons of force.

Interesting point. Hadn't thought of it that way. Forgot about the whole G force thing.

Problem is, the more you design a car to get better mileage the less safe it becomes. IE you need to make the car as light as possible and aerodynamic.

[Frank Lee]

Originally Posted by ConnClark

So far all Aptera have produced as far as safety is claims, marketing, and a limited computer simulation.

The reverse trike makes it more stable in braking which is a good thing but not everything. Lateral stability will still suffer from the trike design. The only way to improve it is to move the center of mass up toward the two front wheels. Unfortunately the more you do this the less control and directional stability the back wheel provides. If you move the center of mass too far forward the car will flip over when applying the brakes.

So far Aptera hasn't produced squat and it could be they never will, rendering this discussion more or less moot as it pertains to Aptera. However as it pertains to trikes in general, seems to me you are really groping for some reason- any reason- to declare trikes unsafe. My suggestion to you would be to never buy or ride in one then.

As far as stability, it is rather simple to make a trike get comparable if not superior stability vs quads, by getting the track, wheelbase, and cg right. For the bulk of what a street vehicle encounters trikes are a perfectly suitable configuration. They are more susceptible to "tripping" i.e. if you find yourself sliding sideways and hit a curb at speed, the trike will probably be more prone to tipping over. At least that's what I've read.

There's a good book on vehicle design and trike stability in Amazon.com: Alternative Cars in the Twenty-First Century: A New Personal Transportation Paradigm (9780768008746): Robert Q. Riley, Wroshik Chee: Books .

[jamesqf]

Originally Posted by ConnClark

Well lets look at its nose height compared to a prius. ( See attached pic )

The Aptera's nose is right about where the hood begins and thus above the bumper. So from this we can conclude that the Aptera is not a low nose car. In an impact with a prius the Aptera will be launched upward.

No, what we can conclude is that the Prius has an even lower nose than the Aptera. Now repeat the exercise with say a Ford F-150 - which is much more common than Prius, so you're much more likely to be hit by one.

And again, why isn't some version of this a problem with every other car on the road? (Not to mention motorcycles.) Unless & until there's a law requiring all bumpers to be at the same height, there's always going to be a good chance of a mismatch.

[cfg83]

ConnClark -

Originally Posted by ConnClark

actually it was well designed. It was just pushed beyond its design limits.

Mannnnn, where's my book report on A Night To Remember ?!?!?!? My conclusion for then and now is that most disasters are a litany of ifs that come to tragic fruition ... if the too-small rudder was designed for the size of the ship it might have turned faster, if the gash had not reached into one water-tight compartment too many, if the Californian had responded to the signal flares it could have saved many of the passengers (debatable), if the lifeboats were fully loaded then more lives could have been saved, if the iceberg had been seen sooner, if the iceberg had been seen *too late* then the ship might have rammed the berg and not compromised one too many of the water-tight compartments, if the ship was not going so fast, ...etc...

CarloSW2

[NeilBlanchard]

ConnClark, the image you are using of the Aptera looks tilted? Try this one:



By the way, deflection away from a direct impact makes a vehicle *safer*. Engagement in a direct impact is worse than deflection. This is one of the lessons I learned from Oliver Kuttner of Edison2.

[jamesqf]

Originally Posted by NeilBlanchard

By the way, deflection away from a direct impact makes a vehicle *safer*. Engagement in a direct impact is worse than deflection.

Exactly. Ever watch a ski jumper?

Likewise, having a moderately-strong structure which deforms/disintegrates on impact, thereby absorbing energy. A completely rigid structure OTOH transmits all the energy to the occupants. For example, compare diving into water (basically zero strength) vs the same dive onto strong concrete.

[justjohn]

Originally Posted by jamesqf

For example, compare diving into water (basically zero strength) vs the same dive onto strong concrete.

Dunno, seems like the concrete would take less damage to me.

[XJguy]

Originally Posted by NeilBlanchard

ConnClark, the image you are using of the Aptera looks tilted? Try this one:



By the way, deflection away from a direct impact makes a vehicle *safer*. Engagement in a direct impact is worse than deflection. This is one of the lessons I learned from Oliver Kuttner of Edison2.

This is true, a glancing blow will transmit a lot less force...but if the structure is not satisfactorily strong, it wont glance, it will just cave in. And lets not forget that the occupants are what is important...if that thing bounces off the bumper of a Suburban and goes rolling down the street, what of the people inside.....scrambled eggs anyone?

The windshield appears to be directly inline with most SUVs rear bumper.....say a bumper with an exposed rear hitch....not good.

[Christ]

Scrambled eggs? Wear a damn seat belt.

Re: windshield- it's also 1/4 of the car away from the occupant, whose seating position puts them well even with smaller mid size cars. Remember, properly seated in a vehicle, you should be comfortable, but nearly straight (i think it's no more than 10° reclined), with arms mostly extended, elbows slightly bent, at or under shoulder height, but not below the pecs major.

That puts the occupant at about half way back the vehicle, with the seat being nearly aligned with the B-Pillar.

Oh, look! There's an occupant in Neil's image, portraying what I just noted.

See how there's almost no way for the occupant to make contact with the windshield? Likewise, something attached to an SUV's backside isn't likely to make contact with said occupant.

[Frank Lee]

Originally Posted by NeilBlanchard

By the way, deflection away from a direct impact makes a vehicle *safer*. Engagement in a direct impact is worse than deflection.

This is the same theory used in military defense like tanks and whatnot: present an angled surface to the most likely direction of incoming ammo/blasts to try to deflect more than absorb.