DIY Active Rear Aero

[freebeard]

aerodynamicist

Did your spell-checker flag it? Mine does, but yes it is.

Exactly reproducing the M-B would be very difficult, but working at the level of race-ready fit and finish isn't at all unreasonable. It isn't all corplast and duct tape here. To pick an example, Bondo's Aerolid


http://ecomodder.com/blog/aerocaps-for-pick-up-trucks/

It's articulated and has a high level of finish.

For materials I would pick PolyMetal and silver solder, and the articulation would be manual using 4 or 6 parking brake cables on a hand lever.

[markweatherill]

Originally Posted by Grant-53

an air supply.

I just imagined a package mounted at the rear of a car, like a deflated and rolled up air mattress in construction. It's attached to the tailpipe, with its own ventilation outlet(s) so the gases will pass through it.
You start the vehicle, it begins to inflate into shape and stays up while the engine is running. Now, when you switch off the engine, it deflates and by some clever elastic cord arrangement, more or less folds or rolls itself back up.
It must have valves to relieve excess internal pressure, it must drain any condensation, and must be proof against corrosion.

[jedi_sol]

Originally Posted by Grant-53

Given the talents shown on this forum I have no doubt this could be done. This is an intermediate level project that a competent technician or community college class could do.

I have no doubt ecomodder can pull this off either. Much like MB r&d, it'll have to be a group effort. I'm sure we all can name at least 5 ecomodders that can pull this off, but the problem will be getting them in the same room

[vibrating_cake]

The other problem is doing it in a "legal" manner. The merc concept wouldn't be legal to produce in the UK. For one the rear lights cannot be seen from the side of the vehicle, it's possible, but in the UK if you cover the tail lights or the number plate the police will be on your case in an instant.
The easiest way I can think is to make a diffuser on runners, with a little motor on a worm gear and two limit switches, fully open and fully closed.
You'd have a step in the floor, but it'd be better.
The material can be anything really. Think of a drawer.
It can reside inside the rear bumper above the undertray using a slot...

The sides I cannot begin to think of a way to do, due to blocking the lights from certain directions ( safety is number one!)
A lengthening spoiler would be very car specific also really difficult, but less so than the sides

[RedDevil]

The tail lights can be mounted on the end section.
Those would be visible from the sides too if that section is a bit longer that the rest.

Could do with extra indicators on the first section just to be sure.
If the sides of the OEM tail lights remain visible I'd leave those connected.

[whatmaycome14]

What if you had a central section (lights and plate mounted on it) that would be tapered. THIS would extend straight back inside the outer shell that would be hinged to be somewhat flexible. The center section would ride on rails.

I'll try to draw a photo to help illustrate what I'm talking about.

Ok, that didn't take long. This is a TOP DOWN VIEW.

Retracted for parking and maneuverability:


Extended 12":

[aerohead]

Originally Posted by markweatherill

I just imagined a package mounted at the rear of a car, like a deflated and rolled up air mattress in construction. It's attached to the tailpipe, with its own ventilation outlet(s) so the gases will pass through it.
You start the vehicle, it begins to inflate into shape and stays up while the engine is running. Now, when you switch off the engine, it deflates and by some clever elastic cord arrangement, more or less folds or rolls itself back up.
It must have valves to relieve excess internal pressure, it must drain any condensation, and must be proof against corrosion.

Here is the original concept from the 1930s



The envelopes ARE subject to aeroelastic forces.I had to include a rigid lower brace to combat Karman Vortex Street oscillations

A dedicated rigid lower structure stiffens the envelope and also fixes the diffuser angle

[whatmaycome14]

I just realized my idea probably wouldn't do anything because the AREA of the rear edge isn't smaller at all. Sure it's extended a little bit, but it isn't tapered any further.

[whatmaycome14]

Aerohead, while great for the aerodynamics, how would you work the issue of tail lights and legal license plate location?

[gumby79]

Originally Posted by whatmaycome14

Aerohead, while great for the aerodynamics, how would you work the issue of tail lights and legal license plate location?

Leds across the flat@rear. Appears to be ~2" tall. Thats more than plentiful for a series of 3/8"leds
Move plate above the transformer section. Withi ts associated light. Geting an extra plate dusnt seem likely. (1on display 1 folded up)