I own a velomobile, which is a three-wheels recumbent tricycle with a hard shell. It is a tadpole configuration with two wheels in front and one at the rear. I had it for over six years and always have a concern regarding rear tire blowout. It never happens to me but many people owning a velomobile have scary experience with rear tire blowout. It loses
lateral stability once rear tire loses traction. The Aptera has a similar configuration. I wonder your design team looks into the rear tire blowout sceneraio or not.
Thanks for sharing. Hopefully someone from Aptera could share their experiences and/ or insight.
As far as the tire...they had on the 2009 prototype..it was an air tire, size: P165/65R14
I haven’t seen a tire specification on the new vehicle. I never owned a run flat tire, if that helps..but any air tire can blowout.
Maybe another ”vote” for the airless tire if viable?!🤞
Oooo! You have a Quest? I am very jealous. In my avatar, the red vehicle is a better.bike PEBL, which is a much more upright electric/pedal reverse trike. I have about 2,500 miles on it in the year+ I have had it.
No flats, so far.
Fantastic velomobile. I have been a huge fan of those vehicles for a long time. Even had thoughts of starting a velomoblie company myself, but low in funds sadly. You bring up a good point about the rear wheel of the Aptera. Maybe with the vehicle being AWD it can cleverly adjust for loss of control in a situation like you mention. But this is a guess
Possibly some stability control over the two front wheel motors would compensate.
Still working on my FAW+ with Graphite/Epoxy skins instead of aluminum...it has been a 9+ years project. I'd want to know all about rear tire blow out...want to get this carbon fiber FAW+ on the road this summer.
The Rotovello becomes very directionally unstable when the rear tire loses air pressure. In one way it acts as an early warning tire pressure alarm system.
I'd vote for airfree tires. I have them on my citezen bicycle, Polaris has them on their ATV. A flat is a rear problem on a 3 wheel vehicle. Most cars today don't even have a spare or a jack at all. It's time for air free tires.
🙏 let‘s watch Michelin’s testing on their airless on the Chevy Bolt
If it works they could be available by 2023 at least for the Bolt. As you know... the Aptera is much lighter. Again Aptera has to focus on launching the vehicle and can’t get into too much new technology yet, nor do they have spare vehicles for their party testing😉
Maybe some sort of run-flat tyre, like they have developed for cars is the solution. Because its a trike they could get away with a heavier fun-flat tyre design without affecting the driving dynamics as much as say a motorbike. This could be combined with TPMS and vehicle estimated tyre wear based on ambient temperatures, driving dynamics and km driven. Given the tyres will be hard to inspect in this platform maybe these monitoring systems will prove essential.
A fun option for tyre wear would be a laser within the vehicles cladding that takes tread depth measurements when the trike is travelling at low speed, giving the operator real time metrics (or more realistically a graphical warning when required) on low tread depth / wear.
air free tires like the Tweel are over due. Most new vehicles don't even come with a spare tire anymore.
Actually the Michelin Uptis is being tested on the Chevy Bolt an Ev in the 3,000 # curb weight range. The Aptera, depending on battery pack, is more like 1800#. (Tweel was Michelin’s earlier airless tire used on slower moving vehicles, like tractors and maintenance equipment) But if the Uptis works on Bolt they said is might be 2024 before they could consider for Bolt production vehicles.
I know Aptera is mainly focused on getting the Development Aptera vehicle out in 2020, so airless tires is not on their radar screen, but perhaps in their “parking lot” of ideas?! 😏
Tweels have a worse rolling resistance / comfort / weight trade off. In a tweel the rubber between the tread and rim needs to absorb the mechanical energy of driving under compression and tension alternatively. This thick rubber support structure needs to wrap around the wheel which makes it heavy. Rubber isn't perfectly elastic so the greater the cross section of rubber flexed the more rotational energy that is turned into heat, increasing rolling resistance. Additionally the lack of a sidewall while decorative increases drag. The rubbers in a tweel need to be very high performance to provide the extreme mechanical properties which makes them expensive.
Pumped tyre rubber is in tension so a thinner cross section of rubber is can be used so less energy loss in deformation of the roads contact patch improving rolling resistance. This also makes them lighter. Also in pumped tyre the pressurised air partially acts as the deformation spring which is perfectly elastic.
Tweels make sense in some specialised high reliability, cost is less of an object, we don't plan to travel fast, we don't care about comfort, applications.
Thanks!
I have to wonder why Michelin and Chevy chose the Bolt for the Michelin Uptis testing?
Maybe the fact that it is Chevy’s smallest EV....Light weight compared to their Volt and ICE vehicles... and the Uptis’ resin+rubber total weight is less than the present Bolt steel wheel and air tire???
Supposedly there is a retread option too with Uptis addressing spent rubber ending up in landfills.
Living in the SW I see what our extreme sun (UV) and heat does to resins and rubber substrates. So that would a be a concern for me. I use products with UV protectant on many surfaces. So with the Aptera Never Charge option and need to keep it in the ☀️ to utilize... I will continue that proactive care. I do, however, like how the Aptera wheel skirts/cover shade most of the tires!
I read more on the latest developments with Tweel like tyres and I think applications in automated urban taxis would make a lot of sense. Anything that requires high performance or efficiency is still better served with a traditional tyre.
I live in sunny Australia and the UV puts cars through the wringer. The heat can damage the plastics inside as well. My ex's old cars speedo needles drooped so she never really knew how fast she was going. I was even thinking an option for the aptera should be gold sputtering like used on an astronauts visor to keep the heat out.
You are probably right on the airless tire and this extreme change does not need to complication a new vehicle introduction, like Aptera. Safety is paramount!
I believe I read that the Aptera’ glass will be a solar reflective glass, but I am not sure how to compare that to tinted glass, which we have on our vehicle in the southwest US. And that makes a big difference to address the heat and sun glare, at least with my % reflective tint choice. There are many laws around this in the various states in the US. I.e. % of tint and even the number of windows you tint. When I lived in east coast state I could not tint as many windows as I can in my present state. Some laws around this relate to law enforcement safety too, as a heavily tinted window and many tinted windows would obscure an officer’s view into a vehicle.
I come up with gold sputtering when there are a million different heat reflective tints already on the market haha, save a dollar. In Aus we can't tint our front window, sides and rear have rules to limit darkness for the reasons you mentioned.
Remember, too, that the rear wheel of the Velomobile is propelling the vehicle: In an Aptera the rear wheel is just one of three propelling the vehicle - one pushing and two pulling. Plus the Aptera front wheels have a vastly wider track than those of the Velomobile, meaning greater stability to begin with.
Also , in one of the Aptera interview video, Chris spoke about a electric motor In each wheel, but.. with auto wheel vectoring too to complement this whole drive system.
Also from the power consumption side...there can be times say on a highway condition where only one wheel will need to power, conserving power.
I guess we will see reality with the 2020 Development vehicles!
As I understand it, "torque vectoring" is usually related to AWD or 4WD systems, shifting the amount of power between front and rear. From what I gather, Aptera plans to use "torque vector steering"- varying the power output between the two front wheels to steer the vehicle when it's traveling at speed, rather than turning the outriggers - which would cause them to create drag, like airplane rudders.