MemberDecember 29, 2021 at 3:28 pm
MemberDecember 29, 2021 at 4:25 pm
Looks like the consequences of Messing with Tire Size/aspect ratio can be More Dire than on an Old Generation ICE Car…
MemberDecember 29, 2021 at 6:09 pm
Sounds like the very success or lack thereof for Aptera may very well be riding on the Elaphe in-wheel motors! They must prove to be as safe/durable/reliable under wide variety of road/weather conditions as traditional under- hood motors or Aptera will not survive! Trust Team Aptera knows this!
MemberDecember 29, 2021 at 7:40 pm
My confidence in Aptera is not shaken by this very interesting post from Guy. I’d like to think Aptera would have already moved to another supplier if there were any red flag issues with Elaphe motors. I also believe the efficiency advantages of in-wheel motors are the only way to create the vehicle Aptera is building. Putting in more traditional motors with drivetrains would just turn an Aptera into another heavy and inefficient 250 mile range EV.
MemberDecember 29, 2021 at 8:29 pm
Very detailed! Even after reading a couple of times could only follow at a high level. Need a few cups of coffee to get through it.
I know Aptera has requested some changes to the off the shelf motors and have identified the bearings as needing replacement more frequently than we are use to. (Another consideration for Right To Repair)
We also know the front and rear suspension has gone through some redesign with the assistance of Roush, an expert in suspension.
It would make sense that the completed Beta that was identified for vehicle dynamics testing would have some of that testing focused on the detail of the physical components of the drive train to include the motors and bearing durability for reliability calculations.
Aptera employs a multidisciplinary approach to engineering where there are engineering reps from all of the systems on the same team. These teams also include representation From major suppliers like Elaphe. I am confident that this approach to Beta testing will identify (If not already identified and remediated with an engineering solution)~resolve any issue with the drive train components. That does not mean we won’t be changing wheel bearings more frequently than we are a custom to with our ICE vehicles.
MemberDecember 30, 2021 at 4:13 am
More than a Pot o Coffee here as well! Just Digging for Understanding, as I Retired when DC Electric Motors were just Great Big Elevator Motors – Commutators the size of Five Gallon Paint Cans/Carbon Brushes, etc…
NUGGETS I Gleaned from the article (For Everyone): Motor Air Gap is Critical, so No “Wide Five” Lug Wheels (A La Oooold VWs, or on Circle Track Racecars); Bearing Set on the “Stock” M700 is as used on the “Smart Car”; Wheels from Same source. (This is possibly where the Motor/Bearing set/Wheels are “Modified”?); annd the Fun Fact – the M700 is capable of 75KW.
We upgraded Our Crane Motors from Ambient/Natural Cooling, to Pressurized Air Cooling, and Ran them at 250% OEM Nameplate rating for a Number of Minutes in a (Moving/Average) Window, to increase Speed/Capacity – Just had to change Brush Composition (A “Black Art” – Har!) and Change them out More Often.
So, I wonder: are the Accel times employing 50 KW, or 75KW, or something in-Between?
MemberDecember 30, 2021 at 6:23 am
Tangentially Relevant IEEE Paper 2019:
I’m gonna go look at Footnoted paper #3 and #10 –
MemberJanuary 1, 2022 at 3:53 pm
The link below is to a post by “Aptera Reboot” of an Aptera webinar in which
Steve and Chris are discussing with two of Elaphe’s principles the use by Aptera
Elaphe’s hub motors. Finding a link to an original version of the webinar directly
from Aptera eluded me.
I’m not sure this copy of the webinar, due to the first 15 minutes not being available,
mentions that the motor’s seals would have to o be replaced at around 30,000 to
40,000 kilometers though one of the Elaphe principles speaking mentioned
that the change interval had been changed to greater number. Some useful
feedback in the comments to the video.
MemberJanuary 19, 2022 at 11:31 am
I am an engineer and I do find this interesting. If you click on Figure 4 in the abstract at the beginning of the article, that figure will be enlarged and shows the concern. We all know the gap between the rotor and stator in a motor is small and must not be allowed to change. This paper is concerned if hard cornering will deform the bearings enough to change this gap.
Traditionally, vehicles have and inner and outer bearings and they are spaced far apart. However in Elaphy’s motors, they are close together as shown in Figure 4. This means wearing of the bearings will allow a greater amount of wobble to occur than if the bearings were farther apart. This wobble would change the gap between the stator and rotor.
This paper shows hard cornering does not cause this. But my concern is, “what about simple bearing wear from usage over time?” I suspect the entire assembly would have to be replaced. Thankfully the light weight of the aptera would reduce this wear.