MemberMarch 22, 2022 at 1:53 pm
ModeratorMarch 22, 2022 at 2:08 pm
Just some notions…
Would it be any different than a conventional car roll over? I.e Not all doors could be compromised
Not all doors and or hatch need to open fully?
Jaws Of Life might be used for egress for a really bad scenario in any vehicle crash..
MemberMarch 22, 2022 at 3:52 pm
That’s a very good question. I played around with my model and considering the weight distribution I really think it will spin flat or bounce the tail most of the time in side or rear impacts. I actually think it could be very dangerous to hit an aptera from the side, side rear or rear since it would seem to want to lift above the hood of the impacting vehicle. A side rear collision on either side would easily have half the tail of the aptera going through the windshield of the oncoming vehicle.
Full Turtle: Given the weight distribution I would think it would be very rare for the vehicle to come to rest on its roof. If it did the forward weight bias should make the rear hatch the best option. Assuming the hatch isn’t an option, the jaws of life could remove the window bar to provide an exit. If the occupants are overweight this might not be large enough and the jaws of life would need to chew into the door enough to cur it free of the hinge<font – definitely would take some time. If the vehicle is in the position and the pack catches fire it would be a really bad situation if for any the hatch isn’t a viable way out.
Lifted Side: In a side impact with a heavy vehicle I would expect it to be more common for the opposite wheel pod to be crushed inward. A vehicle impacting the aptera could easily remain stuck under the Aptera with the belly pan pushing into the hood/windshield. This would leave the vehicle propped up at a 45-60 degree angle and the top door free to move; the bottom door could likely open enough to use the jaws to cut the hinge mechanism. This scenario is concerning for rescuers because it seems like the vehicle could correct and fall back to normal resting stance very easily from this position.
Over 90: A side impact could also cause the vehicle to roll ~110-120 degrees and rest on a crushed wheel pod, roof and tail. I suspect this would be the most common position the vehicle would roll into with a side impact assuming the impacting vehicle does not get trapped under it. In this scenario the upper door would provide easy access and the hatch could likely still open enough. This scenario is also dangerous because the vehicle could shift to full turtle as weight moves.
The rounded shapes makes Aptera very likely to be a danger the rescue teams since the vehicle could change positions as rescuers or occupants shift the weight and it is unstable in the “lifted side” or “over 90 positions” (unlike a car or suv which can rest on a side and be relatively stable). It seems plausible the vehicle could pose more danger to first responders that a traditional vehicle in an accident.
A related thing to consider is pedestrian safety in impacts; given EU rules this could be a big issue for them. If a person hit by an Apera were caught between the wheel pods and vehicle body it would not be pretty. The clearances seem enough that someone could be pinned far more easily than a traditional vehicle.
MemberMarch 22, 2022 at 11:25 pm
Curtis, I get where you’re coming from with your crash dynamics analysis but something tells me your estimate of the nature of the composite monocoque shell fails to factor in how it gains its strength.
The first thing to consider is that the nature of the composite is quite unlike steel. Simply said, steel absorbs energy by crumpling while composites distort and almost immediately return to its initial shape.
The analogy is the dynamic of a medicine ball that distorts when it goes plop on the floor and a basketball or a baseball, both of which will not only bounce, but bounce back to its original shape.
So, while your imagined crash dynamic is more along the lines of a traditional SUV, with doors crushed shut and people wondering how to right the vehicle … I think in most accidents it is going to right its self because of the low center of gravity (much like the Model Y that if placed on its roof, rolls itself upright.)
I do agree that drivers of most smaller vehicles will submarine a left or right rear-quarter strike with likely damage to the windshield of the offending vehicle before possibly bouncing in a single airborne roll over before landing on its ‘feet.’ The rear wheel suspension showing the greatest damage with bent suspension arms and possible dislocation of the wheel and tire.
Because the value of the composite monocoque safety shell in Aptera and Formula one, is to protect the driver and passenger in the event of an accident by being extremely rigid and strong. This includes the door frames which I’m not sure – given Aptera’s weight and distribution – might not distort even in a 100 mph crash with a static barrier. (The Smart Fortwo doors would open after a similar crash by the British auto program Fifth Gear at 75 mph)
But, with all humility, I could be totally wrong and you totally right.
We’ll probably get some ‘real’ information on these dynamics when Aptera does their crash tests, presumably before the end of the year but you got to know that the side-impact test won’t answer the question fully.
While that will be fact, I actually think that a better approach to the crash issues is to craft an Aptera simulation that would factor in aspects of the composite’s strength, speed and handling dynamics in a computer game like maybe BeamNG which creates simulations like this video. https://youtu.be/iMDQzW-eD6g
I haven’t played a ‘car driving game’ since ‘carmeggeddon’ which was not as detailed a program as the BeamNG drive … and its physics were ‘distorted’ …but fun. I don’t know much about BeamNG drive but it does provide a way to make a car in its platform. I think it would be cool if someone might engineer a model.
Aptera could justify the expense of as accurate a digital simulation as possible and, given the structural strength of the composite and the Rousch suspension and successful moose-test results, I’m thinking the Aptera might be a pretty fun ‘virtual’ racer that shows ‘amazing’ safety as it is ‘bounced’ around by existing SUVs, Semi’s and a multitude of sedans.
So what if Aptera created the car in BeamNG and provided those who reserved an Aptera with ‘keys’ to a digital versions in a program like BeamNG (or some other game that does the same.) If there is a fee for the game, it would be on the user to register to play it but we’d all have the opportunity to experience a simulation in all its glory.
It will help keep buyers committed – especially if the digital simulation demonstrates how favorable the vehicle’s safety and performance compares with other vehicles.
MemberMarch 23, 2022 at 9:08 am
Its really hard to guess. I definitely agree the monocoque will generally be quite elastic and will hold together; major failure of it is really hard to predict behavior. Their could still be internal cracks making the entire thing a write-off but we are talking about impacts where basically any vehicle is a write-off anyway. I was mainly assuming deformations of the front wheel covers and suspension would occur under extreme lateral loads since it isn’t designed to hold that way resulting in that and 2 other points holding the vehicle up (lifted side and over 90). The frontal area is designed to crumple but the sides and tail are likely to recover elastically or plasticly deform.
I feel that Aptera very likely has all their ducks in a row regarding passenger safety. Safety for pedestrians, rescue crews and the impacting vehicle might be more problematic and could be an issue for the EU.
MemberMarch 23, 2022 at 9:54 am
Excellent and timely discussion as I was thinking just yesterday about post accident extraction with the doors opening up. An emergency hatch release on the inside could be useful. I was also thing about the Cessna 150 Aerobatic that had D-ring pins in the doors to jettison the door in the event it was necessary to exit (in flight with parachute). The single hinge on the Aptera door might be able to use something like that. Good discussion though!
MemberApril 3, 2022 at 12:38 pm
Just had an idea related to the doors as I was riding my bike, not in relation to a crash, but on sunny nice days would it be feasible to remove the doors and sit them in the garage, aka a three wheeled jeep? or some way to pop the huge none functioning windows off ( and the could pop off in case of some type of emergency) -not a big fan of the tiny side windows…
MemberApril 3, 2022 at 8:47 pm
If you look at how the doors are in relation to the body, it is not infeasible to toot around a neighborhood with the doors open.
When I first found Aptera, I was doing a side gig going around this and surrounding counties taking real estate photos and determined that it would definitely work for me if I just popped the door open giving me a great panoramic view out either the driver’s or passenger side door. I determined that with the door up and out of the way, Aptera would work fine as long as there is not an ignition interlock. I’ve never heard of one.
Then I realized that the Aptera is an attention getter and that with the door ‘open’ you actually have a great place to string a banner across the top between the doors. This works with the Aptera in “Parade Mode” which I imagined to include, (not the steel stand on the rear suspension that includes a hydrofoil 🙂 like in another topic … but) a dolly device like you get from Harbor Freight that you place under the rear wheel giving it free lateral movement. This addition allows tank turns which is the Aptera’s “special talent” in some future set of millions of post Aptera parades.
So, while you could take the doors off for the ‘open cockpit’ feel, I think that is not the best idea given you can open the doors and just leave them open … AND they’ll stay open at appropriate speeds. BUT if you get going faster, you’ll see the doors will slowly close themselves as wind pressure increases and at least approach closing as the speeds increase. (Incidentally, in reverse, the driver would get an increasingly uncomfortable ram-jet experience as reverse speeds increase as the open door(s) would funnel the air into the cockpit.
MemberApril 3, 2022 at 2:31 pm
Given there will be a manual to do things and the simplicity, yes I think you can do it. I think the drag coefficient will increase. You have to drive slowly I would think and I wonder if the stability of the vehicle is going to be impacted. If you remove the doors and boot it should be good so the air can flow and not circle inside the vehicle.