Project: making a permanent Metro Kammback extension

[MetroMPG]

I don't really like declaring the un/success of a mod based only on the butt-o-meter readings, but I did a 100 km highway trip with the partially finished Kammback on the car today and definitely have the impression that the car is getting better MPG at certain speeds than it used to.

It was a 100 km highway trip with city traffic at both ends, and I didn't P&G at all on the highway (just DWL). Managed 71 mpg (US) overall, with a "target" speed of *around* 75 km/h (47 mph) on the highway when there was nobody behind me (limit for most of the trip was 80 km/h) and a downpour/wet roads for the last 10 km.

At a couple of familiar stops/intersections, I definitely coasted in hot and had to jump on the brakes.

Subjective, subjective. Proves nothing! But the difference feels bigger than the 2.5% I saw when I tested the sharp-shouldered prototype.

[gascort]

Sounds like it's probably working!!! We'll be tuned in for the official results!

[lunarhighway]

first impressions can tell something, when you drive the car often you get used to the way it responds so when something changes you'll notice, especially the first few times you drive it. There's other factors to be considered and in the end the numbers matter, but the butt-o-meter as you call it, can be a very sensitive instrument.

[MetroMPG]

That's the problem - I haven't really been driving the car enough to say I'm "used to it".

[brucey]

Just looking at the designs, the permanent one looks a lot more slick/round. Maybe its just the cardboard talking, hopefully not! I guess its going to be too hard to do an A-B-A-B huh?

[akcapeco]

I can't wait to see the test results on this -- I doubt I'd ever do that to my car, but since I drive an essentially identical Metro, though 1.3L, I'm curious as to how much further the aero mods can take the factory body shape.

[akcapeco]

Bump.

What's happening these days with the coolest Metro mod on the planet?

[MetroMPG]

Coolest Metro? Haha -I can think of a couple more that I'd vote for before mine!

I'm on holiday, so no tinker time until next week. Friends visiting! Hanging out at a cottage, kayaking, canoeing, sailing & playing with the kids (not necessarily in that order).

And checking in on EM a couple times a day just to see what's going on...

[aerohead]

Originally Posted by MetroMPG

Phil: every time I settle in to work on the project I think of the goats and your aeroshell. No goats around here that I know of!

Things are moving along. I got the skim coat of body filler on (entire 1 lb can's worth - there's a lot of surface area), and started the sanding process. I think it's going to turn out nicely. Will post some pics tomorrow.

While working, I've been imagining different methods for making a detachable boat-tail...

A lightweight skeleton with fabric skin seems like a good option. Rigid detachable panels would be more complex - harder to make.

My neighbor Bob made a boat tail for his Vanagon with 1/2-inch (13mm) electrical metal tubing (EMT) and doped,dacron cloth.The tubing was bent to match the outline of the VW's tail,and define the shape of the cone,then mig-welded to create the superstructure.Bob attached wooden tack-strips to the tubing with screws.His wife tailored and sewed a Dacron envelope using the skeleton for the form.After the envelope was attached at the tack strips,Bob doped the whole thing like you'd do an old tail-dragger airplane.The boat tail was attached to a Thule bicycle carrier,which itself was secured to the rear hatch without any penetrations.The whole thing didn't weigh 7-kg.His was open at the back.He drove from Sanger out to Seattle,Washington and back a couple times and he swore it was good for 4-mpg.Not the prettiest thing,as Bob was only concerned with mpg,but everyone knows how beautiful a cloth airplane can be,so appearance doesn't have to be an issue.Many options,many ways to go.

[bbjsw10]

Originally Posted by MetroMPG

While working, I've been imagining different methods for making a detachable boat-tail...

Had a idea on this don't know if it would work or not, but what about getting some carbon fiber arrow shafts from say a gun shop. Light weight, strong, and can be folded to a degree. Make a boat-tail to work like a pop-up dome tent when needed just "pop" it out, when you don't just fold it up in hatch. Just an idea.