[ExI] towed evs again

BillK pharos at gmail.com
Mon Oct 23 20:44:05 UTC 2023

On Mon, 23 Oct 2023 at 20:48, <spike at rainier66.com> wrote:
> True this is a weight penalty for needing a heavier frame.  However with this notion the camper is not necessarily long and the aft axle is not very far aft.  Consider the position of the rear axle in this view:
> Imagine your heaviest stuff (the batteries) located forward of the front axle in a bulbous front end (for better air drag characteristics) and above the rear axle.  Now imagine your lighter weight stuff in the longest span and out on the cantilevered aft end.
> Now imagine two scenarios.  One has a driven straight across axle, rear wheel drive only.  But if we don’t care about rough rides (because no one rides in the camper while it is underway) then you can go with four hub mounted motors and the associated weight savings and space savings.
> Now imagine away all the IC engine stuff underneath there, the exhaust system and such.  Now the entire rig can ride lower, and since we don’t care if it is a noisy rough ride (nobody back there while underway) then short rigid springs suffice and we can even tolerate underdamping (since side to side sway doesn’t matter (no one to get seasick back there.)  Lower profile, less wind resistance.
> BillK, to your point, with the heavy batteries mounted above the rear axles and forward of the front axle, the frame weight is manageable and the oscillation problem goes away because of the excellent damping characteristics of good old rubber tires.  The bigger problem is the cost of all that storage, rather than primarily a controls problem.  We could guide such a beast with a Tesla, assuming we don’t get carried away with trying to make the camper push the little Musk-ito to the Sierras.
> spike

Sorry, but you seem to be redesigning the towing camper industry.  :)
Surely they haven't been doing it wrong all this time?

That photo is misleading as it is an RV, not a towable camper van.
You said you didn't want a single axle van, as that would be too small.
Single axle vans also have legal max weight restrictions which your
large collection of batteries might exceed.

Now you want to reduce the length of a twin axle van to allow for
spreading out the axles.

You have to take into account the towing characteristics as well.
The reason twin-axle camper vans are placed in the center of
the van is for better stability and balance. By placing both axles in
the center of the van, the weight is more evenly distributed, which
reduces the risk of the van tipping or swaying while driving. This is
especially important when towing a camper van, as the added weight of
the trailer can make the van more prone to swaying.

Additionally, placing the twin axles in the center of the van allows
for a more even distribution of weight, which can help to improve the
van's handling and braking performance. This is because the weight of
the van is more evenly distributed between the two axles, which can
improve the van's overall stability and traction.

This is critical as your batteries will be heavy, so swaying could be a problem.
I am not even sure that a Tesla could safely tow a thing like this.  :)


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