Mystery of rear underbody…

[Bendotorg]

Do we have definitive information on what the “bump” is at the center rear of the underbody which presumably affects departure angle?

Before launch, I hoped it was a spare tire. Then I thought maybe it was the underfloor storage from the bed.

But I’m not sure that was ever confirmed.

I read everything but perhaps I missed it

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[scottyah]

we're almost certain it's the missing wireless charging feature. I assume it didn't make it in time and they (rightly) decided to stop waiting for it before launching the car. There has been a video that showed the area is just empty for now.

I believe the "official" term for it is the diaper if you want to do more searches on this forum

 

[Gigahorse]

Maybe they will add some battery to future versions to get the promised 500 miles

 

[hridge2020]

Do we have definitive information on what the “bump” is at the center rear of the underbody which presumably affects departure angle?

Before launch, I hoped it was a spare tire. Then I thought maybe it was the underfloor storage from the bed.

But I’m not sure that was ever confirmed.

I read everything but perhaps I missed it

 

[SolarWizard]

aero diaper

 

[JBee]

Do we have definitive information on what the “bump” is at the center rear of the underbody which presumably affects departure angle?

Before launch, I hoped it was a spare tire. Then I thought maybe it was the underfloor storage from the bed.

But I’m not sure that was ever confirmed.

I read everything but perhaps I missed it

The "under tray diffuser" is to reduce drag on the rear by keeping better control of the under vehicle turbulence until airflow separates from the underside if the vehicle. In the rear it's all about trying to keep airflow attached as long as possible, and to make sure the recombining of air doesn't produce unwanted pressure zones or turbulence. This is unlikely to change because of this.

The underbed storage does not go that low, and there is space under there for the yet unannounced wireless charger module for home charging.

 

[RVAC]

Worth noting the diffuser is not one piece with the rest of the bumper, meaning it shouldn't be that hard for the aftermarket or even Tesla, though unlikely, to come up with a 'diaper delete' for those that are willing to forgo the aero benefit and possibility of a wireless charger in favor of better departure angle and looks.

 

[JBee]

Worth noting the diffuser is not one piece with the rest of the bumper, meaning it shouldn't be that hard for the aftermarket or even Tesla, though unlikely, to come up with a 'diaper delete' for those that are willing to forgo the aero benefit and possibility of a wireless charger in favor of better departure angle and looks.

In general I think there is an opportunity to use the rear bumper, the rear defuser, and voids around that whole area, to come up with a enclosed volume that can double as a water tank, for a camper build for example, and integrate 1 or 2 swing out arms for spare wheels, along with a choice of departure angle or aero choices. Or alternatively for use as extra bouyancy for boat mode or water ballast for certain terrain. It's probably the only available partial void to do this with. The front bumper area needs to duct air for the front radiator so is unlikely to have any useable voids.

 

[Cybergirl]

Is the space above this "under tray diffuser" hollow? If so, what are the dimensions?

 

[JBee]

Is the space above this "under tray diffuser" hollow? If so, what are the dimensions?

It varies, but optically it looks around 4-6 inches. The rear underbed storage sits above this void.

 

[HaulingAss]

Do we have definitive information on what the “bump” is at the center rear of the underbody which presumably affects departure angle?

Before launch, I hoped it was a spare tire. Then I thought maybe it was the underfloor storage from the bed.

But I’m not sure that was ever confirmed.

I read everything but perhaps I missed it

Physics and economics are pretty definitive. Worse aero = more batteries, more batteries = more weight and less cargo and/or less range and more money from the buyer.

The "bump" is, without question, to increase aero performance, decrease required batteries, decrease weight, decrease cost and/or increase range. It's not a minor gain, it's compelling.

It's very unlikely to ever be for wireless charging, it's too high and it's not parallel to the ground. Wireless charging becomes horribly inefficient as distance increases.

It will never be for a range extending battery due to the likelihood of it being crushed in typical rear-end collision. The last thing Tesla wants is a PR disaster ala the Ford Pinto in the 1970's. People died. Even though lithium ion batteries are many times less deadly than liquid gasoline, one of Teslas goals is to constantly make their cars safer. Not just safer than gasoline vehicles but as safe as possible.

 

[RVAC]

Is the space above this "under tray diffuser" hollow? If so, what are the dimensions?

Here's a good look:

 

[Tiberius]

Here's a good look:

isn't that the receiver on the left of the pic though? Looks like removing the under tray doesn't help departure angle because the receiver is hanging down anyway.

 

[RVAC]

isn't that the receiver on the left of the pic though? Looks like removing the under tray doesn't help departure angle because the receiver is hanging down anyway.

The angle of the photo is a bit misleading, makes it seem like they are at the same height when they're not. It's not a night and day difference but it should result in a decent improvement.

Couldn't find a clear photo of the current version in my repertoire but here's one from a quick google search. It's an earlier prototype but it illustrates the point:

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