Lotus 7/Locost Aero Rebody

[winkosmosis]

Originally Posted by JackMcCornack

jamesqf mused re...
> ...outboard wheel pants, like Aptera?

I've assumed the Aptera needs a wide front track to give it reasonable roll-over resistance and a small cabin to keep frontal area down. There is some ratio of track to cabin width where wheel pants make aerodynamic sense, where even though wheel pants give the car a higher Cd than a single body unit, if they reduce frontal area enough, then the CdA will be lower than a single body. Either the Aptera aerodynamicists determined that the dimensions of the Aptera make wheel pants the lowest drag option, or the stylists at Aptera determined that wheel pants look cool. My experienced guess is that Bicycle Bob is right and the Aptera is inducing more drag with its three bodies (and don't forget the control arms holding those bodies together) than it's saving with lower frontal area.

> Make the radiator inlet driver adjustable to the current heat load as you are driving. On my car I can adjust it from 0 square inches to 50 square inches depending <snip>

Good idea. I'm wondering how big the maximum opening needs to be to cool my 32 hp diesel. Basjoos, do you ever drive with the full 50 inch opening, and if so, how high a horsepower load do you think you're feeding it then? I doubt you're at full throttle much, and brief bursts can be carried by thermal inertia, but do you ever ask for more than 32 hp for extended time?

The Aptera needs a certain track width. What is the alternative to having indepedent wheels housed in nacelles? Making the whole vehicle wider?



Here is what I think... They do this for a reason

[Bicycle Bob]

Wingtip tanks are good for two reasons and bad for one. They work as an end plate, reducing induced drag, and they load the airframe closer to available lift. However, they reduce roll rate with their inertia.

[winkosmosis]

Originally Posted by Bicycle Bob

Wingtip tanks are good for two reasons and bad for one. They work as an end plate, reducing induced drag, and they load the airframe closer to available lift. However, they reduce roll rate with their inertia.

Is the drag lower or higher than if you made the body thicker to accomodate the extra fuel?

[Bicycle Bob]

If you were to just re-shape the tanks as blisters on the fuselage, and reinforce the wing spar to carry more middle weight, drag would probably be higher. There may be ways to fiddle it back to lower drag, but then a third virtue- versatility - is lost, assuming the tips are replaceable.

[Christ]

I tend to wonder if those tanks are removable for the difference between short and long range trips? Kinda like adding a larger/second fuel cell for when you plan on driving further than your normal range would allow, and don't want to or can't buy fuel where you're going.

[JackMcCornack]

Originally Posted by moTthediesel

J
To look to history for an example of a "clean" body shape that would also be easy to construct, how about the Bugatti Type 32 Tank?

http://www.acmenovelties.net/cars/20...pe_32_tank.jpg

That shape could be built fairly easily using big box store foam insulation board covered with fiberglass. Add a Kamm-back top and full wheel skirts and you could have a very clean and light cover for your running gear in short order.

You might wind up with something that looks like it escaped from the prop room of the Buck Rodgers serials, but I for one don't think that's a bad thing!

That was inspiring, and am I inspired or what? Here y'go, a neoclassic interpretation of the Bugatti Type 32. It's not optimum aero but if the slab sides cost a couple of Cd hundredths, it makes up for it by being really cheap! The only visible compound curved parts it will need are the four fenders, and the Foam Ranger will whip those out in a jif. The rest of it can be formed from flat sheet. So, fiberglass fenders, 26 gauge roofing steel for the rest of it, even with some tubing underneath it and a '30s-Jaray inspired removable hardtop the body will make budget.

Oh, it'll need a few molded odds and ends--headlight buckets, fender inserts, and I think the rear panel should be FRP to make it easy to mount taillights, but should be able to buy a few dinners with the money left over. It's unlikely to be a big seller (99% of the people who want the classic racer look want a Cobra replica, and 90% of them have already got one) but it would be great fun to market: "Can't afford a Bugatti Veyron? Then how about a Type 32?"

The radii of the fillets are as per Hucho, ditto the boat tail (15 degree top slope and side slopes, 4 degree bottom slope), the area of the stern is approx. 2 ft sq and the frontal area of the body approx. 10 ft sq. It's long (176") for a sports car but it's four feet shorter than a Coupe De Ville so it'll still fit in parking spaces. I haven't modeled the chassis (since I already have one), just put wheels and a cockpit where they should go, but I've checked the legal bits (e.g. headlight centers at least 22" from the ground and as widely separated as possible, taillight centers at least 15" from the ground) and the fit bits (the headlight buckets won't interfere with steering, they're clear of the radiator, and hey, Officer, they're as far apart as possible, so there!) and don't see any deal-breaker challenges. Of course if you see a problem, please advise.

[Christ]

Is that thing a Go-Kart? It doesn't look road legal at all...

With all sincerity, I just can't imagine keeping attached flow over that rear slope, and those sharp corners appear like nightmares to a 10 year old.

Maybe I'm wrong?

That said, I'd drive it.

[Bicycle Bob]

I'd definitely narrow the front end, so that air would not be spilling from the front to the side, and get the front and rear stagnation points closer to level. There's not enough air feeding to the bottom of the tail to maintain attached flow at that angle. The cockpit area looks ripe to perform mischeif, too. A classic small flat racing screen would leave a big wake.

Recently, I've started imagining the thickness of the boundary layer on individual components, based on cd, and it has been very interesting. The eye might disregard a thin brake line among streamlined shapes, but it might be making as big a hole in the air as a much larger streamlined wheel pod.

[moTthediesel]

[/QUOTE]


I like it Jack! Maybe not perfect, but better than you'll ever do with the clamshell fenders -- and easy, cheap, & cheerful to boot. But it needs a name -- Locosti? Bugouti?

To my eye the top rear deck angle is not so much a problem, but maybe (if you have the room over the rear wheels) increase the transition radius to keep flow attached? Not so sure about that tuck up from underneath in the rear, vacuum there?

Got any boat graveyards near you? I'd think about looking for a wraparound boat windshield -- with a fastback or Kammback top molded to match you'd just about have it

[samandw]

I wonder if the aft treatment on the Fiat Turbina would be something to look at. The car pulled down a Cd of .14 in 1954, so they must have done something right. Plus, it looks really cool.

http://www.carstyling.ru/resources/c...Turbina_02.jpg