u/Robocreeperplays

I hate frogs

Kinda wrecked my upper back hunching over my drawing tablet yesterday so today I made a vector model on my PC

I've seen a couple people bring up legal overhang limits in the context of interceptors (fig. 1), and I'd like to point out that's not a thing and not something you need to worry about when designing your fictionals.

I've been told that the limits are 3 feet front overhang and 4 feet rear overhang, which is immediately dismissible because something like a brand new Ford F-150 has a front overhang of 37.6 inches, or 3.14 feet and a rear overhang of 48.6 inches, or 4.05 feet, which would mean it has illegally long front and rear overhangs, as well as large vehicles like school buses often having 7 foot front and 13 foot rear overhangs, and obviously the best selling car in the U.S. and a critical part of education infrastructure are not illegal to drive on the road.

Now, those numbers do come from a real overhang limit, but only for cargo. If you are hauling something, it cannot be hanging over the front of the vehicle by more than 3 feet or over the rear of the vehicle by over 4 feet. This applies to anything from hauling 2x4 lumber in your pickup to car haulers (fig.2)^(1), if you are carrying anything that overhangs more than that, you must have marker flags or lights to make sure other drivers can see where the end of your load is.

Again, THIS DOES NOT APPLY TO THE VEHICLE ITSELF.

Evidence supplied in favor of the limit (fig. 3)^(2) actually proves the opposite. This except lays out that states are not allowed to set a minimum overhang limit of less than 3 feet in the front and 4 feet in the rear, as that would conflict with the aforementioned cargo overhang limit. This means that across the country, the minimum overhang limit is 3 feet in the front and 4 feet in the rear, and states are only allowed to make that limit longer.

Basically, unless individual states decide to start strictly enforcing that 3 foot front and 4 foot rear overhang, which would prevent all full-size pickups, semi trucks, buses, etc. from driving on their roads, the only real overhang limits are elevation changes in the road that you don't have the approach/departure angle for if your overhangs are too long.

Keep on designing away to your heart's content!

Sources:

^(1) https://ops.fhwa.dot.gov/freight/publications/size_regs_final_rpt/
^(2) https://www.govinfo.gov/content/pkg/CFR-2011-title23-vol1/pdf/CFR-2011-title23-vol1-sec658-13.pdf

https://www.facebook.com/share/1CkhSJfP1p/

Shading round things is hard

(Using the same interceptor model as last time because I'm lazy)

The idea behind this one is simply to use big fans to pull a vacuum under the vehicle that will suction it to the road and prevent sliding, inspired by the Chaparral 2J Can-Am race car that used a similar system to enhance handling.

(Probably shouldn't be used on any particularly loose surfaces)

Edit: if my math is right, just a 1 psi pressure differential from under this particular vehicle to the outside would produce roughly 17,000 lbs of downforce.

Just a quick and dirty concept that popped into my head.

In case the gif didn't explain it well enough, the idea is to have a single spike mounted near the front of the vehicle and a fin similar to what's found on a modern LMP car. If any strong enough crosswinds come along while deployed, the fin will catch the wind and swing the rear of the car, but because of the spike, instead of just sliding into a ditch it will pivot and end up pointed into the wind.

Edit: a transverse roller could maybe be added in the rear to make pivoting easier as well