Random Aerodynamic Oddity of the Day Thread

[freebeard]

In case you don't know why I'm a big fan of James Watt's 4-bar linkage, watch this:

https://www.youtube.com/watch?&v=wm0bO-Szfn8

Just A Car Guy: whoa... Peter Jackson must have been inspired by this old beast for his new movie Mortal Engines? Or maybe, the next Transformers movie could use this as an antique robot

[19bonestock88]

Originally Posted by kach22i

Not normal............................

https://jalopnik.com/meh-car-monday-...nce-1796433743


More on that car/van here:
https://jalopnik.com/this-renault-le...u-d-1626907714

https://jalopnik.com/this-renault-le...u-d-1626907714

I had no idea Daihatsu made a van version of its Midget kei truck... kinda cool

[kach22i]

Originally Posted by 19bonestock88

I had no idea Daihatsu made a van version of its Midget kei truck... kinda cool

I did not know that these were single seat - cool.

Daihatsu Midget
Daihatsu Midget Overview - Landscape Mini Trucks

Dating all the way back to 1957, the Midget (and Midget II) is a single seater Kei Truck that comes as a 3 wheeled (pre 1996) and 4 wheeled (post 1996) variant. The second generation Midget II was introduced as a concept at the 1993 Tokyo Motor Show and came available with 2 seats....................

They are available in one seater or 2 seater.................

Is the second seat in tandem (not shown) or in the driver's lap?

EDIT-1:

Answered my own question, looks like it is not intended for wide body Americans - haha.

https://www.rightdrive.ca/model/daihatsu/midget/



I think that I found it's driver/operator/passenger.

https://gfycat.com/gifs/search/third+l

[freebeard]

The 1911 Franklin had a steering wheel wider that the seat.



I like this a lot. It just needs a 'trucker girl' mudflap.

[cRiPpLe_rOoStEr]

The design of that Daihatsu Midget II is interesting, but I'm not sure if I would be able to register one in my country. BTW there was also a Midget IV prototype featured in the '97 Tokyo Auto Salon, which had a microvan body and a rear bench seat.

[kach22i]

Truck Outfitters of Durham and Garner, Buildings & Truck Accessories

[freebeard]

That's an oddity? All it needs is a flap of [magnetic stick-on car door sign] material riveted to the back edge of the cab.

...and, I guess, a ferrous strip riveted to the fiberglass.

[Bicycle Bob]

I just noticed that ship's propeller in this thread, so here's a recent rant:

When asked to build a better pedal-propeller system for small boats, I knew that the physics were such that similar shapes worked in air and water, just at different sizes and speeds. Instead of designing and carving my own propeller, I just tried model aircraft props, with instant success in racing. The prop pictured is modified with a tail fairing that is fully streamlined, producing a single, continuous trailing edge to minimize drag.

There are two reasons why marine propellers usually have such stubby blades. One is packaging - they just take less room, don't hit bottom in harbour, require less gearing, cost less, and so on. The other is probably historic, arising from the day that an early screw-propeller builder was challenged to a competition with a paddlewheel steamer. The ships were to be tied stern to stern, and the loser dragged backwards. Operating in still water, a prop causes circulation, and that strictly limits the efficiency available. This Betz Limit also applies to windmills - how much can you take from the wind before it just goes around instead?

Once under way, however, there is a continuous supply of fluid available to push on, and we try to disturb it as little as possible, so that we are not pushing on something that is running away from us. For this, we use the Froude Equations. Unfortunately, these have not penetrated into Marine Architecture, and the boffins there are still patting themselves on the back over beating the Betz Limit by a few percent, which should itself tell them that their theory is misapplied.

Like a wing, an efficient propeller blade is long and thin, so that little fluid is lost over the tip. We don't need a full disc of blades, because each one has a large, invisible wake. Looking at the front view of an airplane with the prop circle shown vs a boat gives an idea of the change in proportions that should be made. Larger, slower propellers should increase mileage about 20% between ports, but will usually have to be stowed one way or another near land. This is not nearly as ungainly as paddle wheels or sails, but it will look odd at first, and the first few will be expensive. We have to get the word out to the people who pay the bills, and those who fight oil use. A windmill gearbox or two might work for a coastal freighter, to keep costs down for prototypes. Propeller shafts that are extended and geared down for a large propeller, and hinged to swing up for shoal waters would be the first configuration I'd try.

Re: Square tips in ducts, etc. If you have a diameter limitation, it is better to prevent loss over the blade tips with a ring of material, but if not, that material does more good as more blade length.

[freebeard]

Interesting. Could the ring duct be reduced to upturned winglets at the tips similar to what they use on airliners to reduce vortexes forming at the wingtips?

[Bicycle Bob]

Originally Posted by freebeard

Interesting. Could the ring duct be reduced to upturned winglets at the tips similar to what they use on airliners to reduce vortexes forming at the wingtips?

Yes, that can be done, although it seldom is. Wingtip fences are most popular on cars. They raise skin friction, may cause complications in crosswinds and turbulence, and reduce the effective span due to the build up of stagnant air in the corners where a wing-root fillet would look familiar.
The Whitcomb winglets on airliners are interesting. They "sail" on the induced vortex to recover some thrust, but they would do just as much good as increased wingspan, and be easier to build. However, more wingspan means higher rent at airports.
The "best" wingtip is also subject to construction considerations, but the debate over the best shape has come down for the one shown, the "Finch Tip" which tapers finely to a straight trailing edge to minimize the tip vortex.