Teardrops n Tiny Travel Trailers

asianflava wrote:For over volume in a space the sphere is actually the most space effieicent. It holds the most volume for the least amount of surface area. The problem with that is, we and the things we store aren't liquid so we can't take full advantage of this property.

A sphere shaped teardrop would be interesting! I think I would have one heck of a backache in the morning from sleeping in a sphere.

In general we are building with 4x8 sheets of plywood. The more you cut off a 4x8 sheet of plywood the less space you will have in your teardrop.

George is right. The sphere is the least surface area for a given volume. We have a guy who works here that is a real energy efficiant home nut, you know underground homes and all. Lots of fun to sit at the lunch table and hash out designs with him. The guys in the super energy efficiant home world acknowledgs the sphere is the best but impractical so go with the next best thing. That is an octogon. It has flat walls for ease of construction and utlity inside (you can actually push a cabinet against a wall) and it is nearly exactly the same energy efficiancy numbers as a sphere.

Now, how does this relate to a teardrop? Hmmm, don't know.

Cary

I knew someone would do that surface area thing, my wife and I looked at these for years. This was our first dream house......
http://www.cordwoodmasonry.com/Cordwood.html
our second choice
http://www.deltechomes.com/

mwatters wrote:I ride a small 250cc motorcycle. I like the efficiency and easy control. Most folks are riding 1100+ bikes. I've had two different CARS with engines about that size. I don't understand why anybody would want or need a 700+ pound bike with a bigger engine than most small cars (or the equal of some minivans). They don't understand why I DON'T want it. Fine by me.

Mike

I think it depends in what you use your motorcycle for. I never want to cross country (USA) with even a 500cc motorcycle. Long trip (more than 5000 miles) traveling with motorcycle is not for "little" bike.
Hope this help
Nick

mikeschn wrote:In the 40's aerodynamics was important. Teardrops were rounded to improve the aerodynamics and improve gas milage.

Mike: small correction: in the 1930's (and early 40s) the appearance of aerodynamics was important. Household objects such as pencil sharpeners and radios were all "streamlined" to match the prevailing aesthetic.

Teardrop trailers are not a particularly aerodynamic shape. But they look they they are!

Rik

Hi Rik

Actually the teardrop is a very aerodynamic shape (as in low drag) the most aerodynamic production car ever the Tatra T77a was released in 1935, even today only the occassional Concept or prototype gets anywhere near its drag co-efficient of .212

here is a couple of pictures of the most aerodynamic Production car ever, note the shape, yes the two pictures are odd, after brief google could only find T77 rear and T77a front view but you get the idea

Just to give you an idea of how good .212 is chack out the following


Ferrari F50 .372
Ferrati F40 .34
Porsche 997 .28
Dodge Charger .33

Best known prototype is

Probe V prototype, 1985 .137 so damned rare I cannot even find a picture !!!

Hi Powder

No a bullet isnt for years it was assumed that Ernst Mach was right, but Whitcomb eventually saw the light.

In order to see a solution that went beyond existing theory, however, Whitcomb also had to be willing to break free from accepted rules, or paradigms, of aerodynamics.23 In the late nineteenth century, Ernst Mach had shown that a bullet-shaped body produced less drag in flight than any other design. This accepted "paradigm" of aircraft design led to the basic fuselage shape employed by transports, World War II fighter planes, and even the Bell X-1 rocket plane. It was also still the accepted rule of thumb as engineers began to design the first turbojet-powered supersonic aircraft. The assumption that a bullet-shaped fuselage was the most efficient aerodynamic shape, however, led researchers to look elsewhere for elements that could be modified to reduce the drag of aircraft at transonic speeds. To see the solution that Whitcomb envisioned —indenting the fuselage in the area of the wing to reduce the dramatic changes in the aircraft's overall cross-sectional area from nose to tail— required going against a "truth" that had worked and had been accepted for over fifty years.

Bit dry but there is plaenty more here

http://history.nasa.gov/SP-4219/Chapter5.html

Size doesn't ALWAYS matter! haha

My new boyfriend has a 4x4 diesel truck for pulling his big 5th wheel.
He was telling me about all the things he needs to do to get it ready for camping this fall... and I think he's just being polite when I 'm talking about the teardrop I want. He wonders what I would rather be in when it rains ( like I "plan" on camping in the rain?) or being able to stand up (I'm don't sleep standing up and that's what the cabin in the tear is for!)
And I love my Honda Accord... I depend on Honda's and mine will be paid off in a few months!!! So why would I want to trade it in and have payments again for a bigger gas guzzler to haul a small new pop up that I don't have the $$$ for ...

And having been to only one gathering , but hearing all the fun everyone has.. why would I want to go camping and just sit inside a big RV all day? Why not sit by the fire, chat with new friends, walk by the water, watch the boats, go sightseeing, fresh air and relaxing in the sun, cooking on the coals and the DO's... potlucks, funny stories...
Heck - stay home if you want the air conditioning, the remote control and big screen...



Julie

GeorgeTelford wrote:Actually the teardrop is a very aerodynamic shape (as in low drag) the most aerodynamic production car ever the Tatra T77a was released in 1935, even today only the occassional Concept or prototype gets anywhere near its drag co-efficient of .212

George,

That Cd figure doesn't sound plausible.

The Tatra 87 (very similar body shape) was claimed to have a Cd of 0.244 from a 1/5th scale wind tunnel model test, but the claimed top speed gave a calculated Cd of 0.31. In 1979 a real 87 from the Deutsches Museum was put in VW's wind tunnel and the result was a Cd of 0.36.

According to my Tatra book, the 77a did 150km/hr on 75bhp and the 87 did 160km/hr on 75bhp, so the 77a probably has a higher Cd than the 87's 0.36.

The teardrop shape, like the Tatra shape, was thought to be aerodynamic at the time and, in the case of the Tatras, they were much better than the cars of the time (Cd 0.6-0.8 ), but they were both out of date as soon as Kamm published his work in 1934.

Andrew

Hi Andrew

The Tatra 77a's Drag CD is mentioned everywhere, from automotive encyclopedia's to original testing specs.

Also the 77a was a product from 1935 on after Kamm

The 87a had a higher cd of .251

The Tatra 77a remains the lowest cd of any production car ever, I think Porsche, Ferrari, McClaren and a few others would have said something by now

Ferdinand Porsche admitted to looking over Ledwinka's shoulder hence the Beetle influence and later of course the beautiful evocative 911shape. Note also the Air cooled rear engined designs, Mostly english, have slipped one Czhec site in just for some cultural flavour.

http://www.ukcar.co.uk/history/Tatra/

http://www.tatraportal.sk/?ukaz=popisky/t77&lang=sk

http://www.autohistories.com/tatra/Tatra_history_auto3.html

http://www.evworld.com/view.cfm?section=article&storyid=813

http://www.ltv-vwc.org.uk/wheelspin/ws_mar_2003/Tatra-history-pt1.htm

yep; 77a was the way to go!

angib wrote:

GeorgeTelford wrote:Actually the teardrop is a very aerodynamic shape (as in low drag) the most aerodynamic production car ever the Tatra T77a was released in 1935, even today only the occassional Concept or prototype gets anywhere near its drag co-efficient of .212

The teardrop shape, like the Tatra shape, was thought to be aerodynamic at the time and, in the case of the Tatras, they were much better than the cars of the time (Cd 0.6-0.8 ), but they were both out of date as soon as Kamm published his work in 1934.

George: yes, a teardrop shape is very aerodynamic, but like I said:

Teardrop trailers are not a particularly aerodynamic shape.

Teardrop trailers are not nearly long enough or the curve gradual enough (see the Tatra) to be a true teardrop shape or very aerodynamic. Andrew can probably help me out with a more detailed explanation.

Just for comparison to some of the other cars listed, the Cd for a 2003 VW Passat sedan (that's "saloon" for you, Andrew!) is listed at 0.27.

Rik

Wouldn't the most aerodynamic shape be something like a pencil? Sharpened of course, with a slightly used (rounded) eraser. Something along the lines of a lakester.

puerile

Man...had to look that one up! adjective= childish

This site is REALLY educational.