Prius Removable Kammback

[ENERGYprof]

I bought a "towing package" for my little black peanut car (no, not for towing a mobile home-- for my bike rack and for my little aluminum rack that I use to haul my paramotor around). In looking at how easily these weight-bearing accessories slide into and out of the "towing hitch" receptacle, I have drawn up a design for a removable kammback that works as an aero mod, improving mileage, while at the same time not hurting resale value and providing more cargo space.

The so-called towing package fits great is available on ebay for about $100 or so, it bolts right on with only a minor cut in the plastic underpan and removal of the rear frame tow attach points.

The design for my removable unit is a basic kammback shape, with plexiglass on the sides to allow visibility for rear lights and plexiglass on the top to allow for driver visibility. To keep it from wobbling around in the hitch or rubbing against the paint, a soft foam rubber gasket would be used to make a seal against the car, and the unit would have to be pushed against the car tightly in order to put the rear pin into the hitch receptacle. Provisions for accessing the hitch need to be made, as well as a removable lid for hauling large items (like my paramotor!).

It should be made from aircraft grade aluminum tubing, with some sort of paintable skin that is rigid in sheets and flexible (id est, not coroplast). Maybe aluminum sheeting or fiberglass?

Using this idea, can any of the talented artists here post some conceptual drawings of what this thing should look like?

Can any engineering people post recommendations for dimentions? Framing specifications and load limits for stock rear springs?

Can an aero whiz suggest computer modeling ideas? Incorporated rear wheel treatments?

Ideas about exhaust considerations?

Ideas on how to make it crumple in an accident?

Anyone want to build one of these with me?

[NiHaoMike]

I'm not sure how to design one but the Aerocivic has one of the best Kammbacks I've seen so far. One revision even sacrificed itself in an accident to protect the car it's attached to.

[ENERGYprof]

That's the general shape I'm going for, but removable and with a higher WAF rating. (Wife Acceptance Factor)

[Bicycle Bob]

If you want that much help, you probably shouldn't specify the materials yourself. There are a dozen good ways to get similar results, but most potential craftsman will only be comfy with one or two of them.

[ENERGYprof]

My ideas are a starting point to be improved upon or perhaps scrapped altogether for a better direction.

The more people that comment on this, the better.

[NeilBlanchard]

Hi,

What version of the Prius are you working with?

[ENERGYprof]

Its an '07

[SVOboy]

The difficult thing is going to be having a way to lift it on and off the car easily, since I expect it would be large and cumbersome.

As such, do you have a goal for the weight of it?

[ENERGYprof]

We could certainly keep it under 50 pounds without too much of a problem I would think... that would limit its load capacity a lot I'm sure but I don't need to haul rocks.

[SVOboy]

I guess since it's just a kammback and not a full boattail that's possible. Might be difficult though