Lotus 7/Locost Aero Rebody

[TedV]

The definition of "sports car" has changed since 1957. A link from the link above MOTOR test table shows 0-60mph time of 10 seconds. I think a modern Minivan would outrun and perhaps out handle it. as this article here points out Soccer Moms' Revenge: Grassroots Motorsports Magazine Articles

[Arragonis]

0-60 in 10 seconds when you are about 6 inches off the floor is plenty sporty for me, plus of course Minivans take the unscientific (dumb ?) route to performance of most modern cars - bigger engine and more POWAH instead of efficient design.

As for outhandling - comparing a minivan to 2 cars both of which have acknowledge handling issues (engine at the wrong end, too narrow track & soft springs) is not really fair.

Lotus XIs and the Westfield clones have been happily mixing it with purpose built racing machinery on the track for decades.

[jamesqf]

You also have to figure in all the improved technology which could be put in a Lotus XI-type car. Notice little comments in that motor article about carburetors (carburetors?!?!) without chokes (Daddy, what's a choke?), an engine that doesn't consume much oil (nowadays I put 2.5 quarts in my Insight at an oil change, and take out about 2.49 quarts 7500 miles later).

Suppose you build a Lotus XI clone using modern technology: what sort of performance & fuel economy would you expect? Even the current Lotus cars, over-engined as they are, score near the top of the annual CAFE stats.

[JackMcCornack]

> I have a hard time believing any ICE car could acheive 40mpg at LeMans.

I researched that question myself recently, it does sound pretty incredible (as in: not credible). I believe the error comes from MOTOR magazine testing mileage with Imperial gallons, which are 20% larger than US gallons. So how 'bout 30mpg at Le Mans? The Lotus 11 that won the 1957 Index of Performance is alleged to have done slightly better than that with a 750cc motor.

Mind you, the '50s were the last hurrah of streamlined road racing cars (by the early '60s, road racing was all about downforce and horsepower) and that car was aiming specifically at winning the IoP (where fuel economy was the major factor), but still, it couldn't win the IoP if it didn't finish, and to count as a finisher a car had to go at least 70% as far as the overall winner...so they weren't exactly hypermiling.

> I think a modern Minivan would outrun and perhaps out handle it...

The first Lotus 11s weren't all that great handling, but they got better.

> ...as this article here points out

It also points out that they put replica antique tires on the Porsche 356 ("...period-correct 165R15 Michelin XZX tires sourced from Coker Tire...") and upgraded the Honda Minivan with $1100 worth of tires and wheels to improve traction. Putting a set of Goodyear Advantage Fuel Max tires and Drag DR-9 wheels on MAX made it considerably more autocross-friendly.

[JackMcCornack]

I put a flat diffuser plate under the rear axle and fuel tank. It seems to have helped (I didn't do ABBA testing, but then again, I didn't break the 100 mpg @ 55 mph barrier until I added this diffuser) but with the sharp 6 degree edge where it hits the cockpit, and the hole for the diff to droop through, it's still pretty turbulent. See for yourself.

https://www.youtube.com/watch?v=9pyQfyKYfRo

However, air never stays laminar after it's been drug under a car, and I think there will be diminishing returns from here on out. Do you think a curved diffuser with a gentle transition from the horizontal belly of the cockpit would be worth the effort?

[nemo]

Another question would be how much the downstream camera affected the tuft test. The camera and mount appear to be centered, in direct line with the cut out for differential, try offsetting it and see if you get different results.

[Bicycle Bob]

I'd have to see pics or drawings of the current area to be covered by the curved piece proposed, but there should always be a curved transition to any afterbody surface. Laminar is usually impossible, but attached flow is still very good to achieve.

[aerohead]

I've no data on diffusers other than what Hucho published,or the original sources he used.These all have just a simple angle,although I was given to understand that 4-degrees was the maximum upward slope angle which would guarantee attached flow.
Since the tufts are 'flying' a bit,rather than attempting to polish the surface of the diffuser,it would appear that the boundary layer is somewhat compromised under there with eddy flow underway.The tufts do mostly point to the rear so there's no apparent recirculation,so she's helping.
Love the camera work! These images are as good as anything coming out of a world-class wind tunnel.Thanks!

[JackMcCornack]

My summer project (one of two, actually; my other project is to make molds for the nose etc 'cause there are folks who want copies of this bodies) is to make an enclosed cabin.

At present, my trunk deck drops back at the Hucho-mandated 12 degree angle, but my cabin is going to sit on top and taper in from the side as well as tapering down. The question is, with the cabin, should my rear deck have a shallower descent angle, since the tapering sides of the cabin will lower pressure on top of the rear deck, thus increasing drag (induced drag, presented as rotors behind the car) the same way a more-than-12-degree slope would increase drag? Or am I overthinking this?

[Bicycle Bob]

That depends - on so much thinking that supercomputers boggle at it. You are wise to be cautious, and probably the only quick, reliable way to the answer is to try a mock-up that can be adjusted and tested.