Aerodynamics-- request for project help - PeachParts Mercedes-Benz Forum

hetiticth · #1 10-08-2013, 05:55 PM

Recently I have been looking into some of the German cars of the mid to late 1930s that were focused on attaining as low a drag coefficient as possible, in hopes of finding one that I could recreate.

So far, this has been the best candidate: The 1939 Maybach Stromlinienkarosserie.

This car appears to be a very good platform for a high performance vehicle, though there are a few issues that I have encountered. While some of these issues I could probably work around, most have become an issue.

The first is a lack of information on the car. I have found a few different sources saying that it was designed to test tires on the autobahn, and it was capable of getting up to 150mph on a 150bhp engine. I have only found one sort of blueprint for the car, which is below:

A few other pictures of the car:

This is about all I have on the car. There are a few more photos, but nothing that really helps with recreating it..

Another issue that I have encountered would be cooling. Ideally, this would be a water cooled engine (probably a small block chevy.. parts are easy to come by). Unfortunately, I have been having issues with devising an efficient cooling method without having to custom-make a radiator. The reason this is an issue is that I would like to keep the drag as little as possible.

I have yet to decide where I would place the engine, though I do know that I will be wanting to use a dry sump system for the ease of maintenance (it will have sheet metal on the bottom of the car), though that can be set up later.

Would a front engine, RWD setup be ideal for something like this? If I were to race it, I would likely be doing drags, though I do want it to have a decent top speed.

And finally, for the aerodynamics experts out there, I have a few questions:
What would be the best way to get minimum drag?
Should I make the angle on the back of the cabin less sharp so air sticks to it better?
Anyone have a decent idea of how to find out the drag coefficient of my car without taking it to a wind tunnel?
Would I benefit much from lowering the car?
Should the front end be pointier or keep the generic teardrop shape?

Many thanks!!
~hetiticth

P.S. I am also looking into how to cool radial engines as well. I am thinking of trying to make one that runs well in an automobile, and I also want it to be water cooled. It will be a vertical setup though, which is unusual for radial setups (the crank is vertical). Any ideas would be welcome!!

P.C. · #2 10-08-2013, 06:01 PM

Air cooled Porsche flat-six. You could hang it behind the rear wheels in classic 911 style, or go mid-engine for better dynamics, as in the 1970-72 Porsche 914-6.

Or, find a candidate car with body-on-frame design, such as a late seventies GM midsize, or even a Chevy S-10 pickup, and use that as a foundation for the body.

Or, build your own old-school kit car, using a old VW Beetle floorpan.

If you plan a very tapered front end, not having an engine to work around is helpful.

MTI · #3 10-08-2013, 06:06 PM

Drag racing, probably not . . . Bonneville more likely.

P.C. · #4 10-08-2013, 06:12 PM

Quote:

Originally Posted by MTI

Drag racing, probably not . . . Bonneville more likely.

Bonneville? You better have more than a passing acquaintance with aerodynamic design, unless you also have a pilot's license.

MTI · #5 10-08-2013, 06:16 PM

He mentioned drag racing, which wouldn't provide much benefit in distance to use the low Cd numbers he is shooting for. Speed trials, like Bonneville, over a couple miles would be a better application.

Skippy · #6 10-08-2013, 06:49 PM

Need more information. What are the goals of this project? Budget, in terms of both time and money?

t walgamuth · #7 10-08-2013, 07:16 PM

The nose is too high on the drawing. the actual carl looks as if it is drooping more which will keep it planted at speed. The shape of the radiator is normally rectangular, sometimes laid down for a lower nose with ducting to force the air to it. looks as if you can pick your poison on the engine location as there is plenty of room for it anywhere. Front engine front drive is the simplist but the juxtaposition of the front wheels to the firewall suggests a front engine rear drive setup.

I dig the tires which look like snow tires.

Cool car!

hetiticth · #8 10-08-2013, 09:50 PM

Quote:

Originally Posted by P.C.

Air cooled Porsche flat-six. You could hang it behind the rear wheels in classic 911 style, or go mid-engine for better dynamics, as in the 1970-72 Porsche 914-6.

Or, find a candidate car with body-on-frame design, such as a late seventies GM midsize, or even a Chevy S-10 pickup, and use that as a foundation for the body.

Or, build your own old-school kit car, using a old VW Beetle floorpan.

If you plan a very tapered front end, not having an engine to work around is helpful.

Thanks

I do understand that it would be a lot easier to use a car already built, or add on to an existing frame, but I am trying to avoid that for a few reasons. I may try to use the design for a frame to make it, but I don't think I would take a frame off of another vehicle, because I am trying to learn more about metal working, and building my own frame would allow for more flexibility with the size of the vehicle.

And I think that there will be a lot of value in creating your own vehicle, rather than using another, because you know all of the intricacies of the vehicle. But the main reason I want to stick with the Maybach is because I think it looks awesome!

hetiticth · #9 10-08-2013, 10:13 PM

Quote:

Originally Posted by MTI

He mentioned drag racing, which wouldn't provide much benefit in distance to use the low Cd numbers he is shooting for. Speed trials, like Bonneville, over a couple miles would be a better application.

Quote:

Originally Posted by P.C.

Bonneville? You better have more than a passing acquaintance with aerodynamic design, unless you also have a pilot's license.

Drag racing is what I would be doing the most, just because there is a drag strip nearby, and I know how everything works. I would like to try Bonneville sometime, but it is a bit far away.

While CD doesn't effect much in short drag races, it begins to help in longer ones. The reason I am shooting for a really low CD though, is for a very fuel efficient high-speed car.

Mölyapina · #10 10-08-2013, 10:15 PM

Just a thought -- the metalwork in shaping the body panels may be one of the tougher parts of the project. I've always thought it would be fun to build my own car, but I'd thought of something more like a Jeep-type body for ease of fabrication. What kind of frame would you be using? Ladder? Perimeter? Where would you get the metal for this project?

I'd say go nuts, at least design it. Designing is a lot of fun, and you'll certainly learn a lot in the process. If you actually build a car, no-one will be able to question your user title

.

hetiticth · #11 10-08-2013, 10:19 PM

Quote:

Originally Posted by Skippy

Need more information. What are the goals of this project? Budget, in terms of both time and money?

This will be a long term project. It is still in the design stage, and will likely remain so for some time to come. If I finish the design in the near future, the earliest I would be able to start would be in the summer of 2014.

My goal would be to create a unique vehicle, which will surpass a current factory automobile in both efficiency, performance, and looks, for a fraction of what it would cost to get a similarly performing vehicle new. I plan on expanding on the designs and whatnot during my time in college.

Mölyapina · #12 10-08-2013, 10:19 PM

I would also look into what you need to do to register a homebuilt vehicle in NM. I wonder what would happen if you got hit in the car in terms of insurance... how would they determine the value of the car and how would they determine the repair cost?

hetiticth · #13 10-08-2013, 10:22 PM

Quote:

Originally Posted by t walgamuth

The nose is too high on the drawing. the actual carl looks as if it is drooping more which will keep it planted at speed. The shape of the radiator is normally rectangular, sometimes laid down for a lower nose with ducting to force the air to it. looks as if you can pick your poison on the engine location as there is plenty of room for it anywhere. Front engine front drive is the simplist but the juxtaposition of the front wheels to the firewall suggests a front engine rear drive setup.

I dig the tires which look like snow tires.

Cool car!

I think that this was one of the earlier designs for the vehicle, and that they changed a few things when making it. Notice the lack of a front wheel cover as well.

Almost 100% sure that the car was front engine, RWD.

P.C. · #14 10-08-2013, 10:23 PM

Quote:

Originally Posted by t walgamuth

The nose is too high on the drawing. the actual carl looks as if it is drooping more which will keep it planted at speed. The shape of the radiator is normally rectangular, sometimes laid down for a lower nose with ducting to force the air to it. looks as if you can pick your poison on the engine location as there is plenty of room for it anywhere. Front engine front drive is the simplist but the juxtaposition of the front wheels to the firewall suggests a front engine rear drive setup.

I dig the tires which look like snow tires.

Cool car!

I would look at 1968-up Corvette's for GM's solution to having a low radiator height while addressing the cooling demands of a small block Chevy.

Mölyapina · #15 10-08-2013, 10:24 PM

Ah, and please make it with a standard

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