Aerodynamic of the reverse tear...

[aggie79]

Besides teardropping, I spend a lot of time (too much according to my wife) following Formula 1 motor racing.

These open wheel vehicles are the epitomy of computer aided design and wind tunnel testing. Granted, they do balance aerodynamic drag with aerodynamic downforce; however, the end result is a "slippery" vehicle. But, you'd never guess by looking that they are "aerodynamic."



Millions of dollars are spent each season customizing the wings alone to suit the characteristics of the different racing venues: http://www.formula1.com/news/technical/2009/822/708.html

Morals of the story: 1) aerodynamic design is complex and 2) aerodynamic "look" is not equal to low drag.

[Ageless]

True; even though none of us will ever get close to 200 mph

[angib]

....however, the end result is a "slippery" vehicle....

I think the only fair response to that is NO!

For sure, an F1 car has a low drag coefficient, considering how much downforce it creates, but it ain't slippery by any normal standards. The drag coefficient is about 0.9-1.0 so they are a lot less slippery than a tractor/trailer, for example.

About the only thing with a similar drag coefficient is a parachute!

Andrew

[Ageless]

If you want to see 'slippery' go to the Salt Flats; they just want to go fast in a straight line

[Miriam C.]

Drag coefficients???? aerodynamics????? fuel economy ??????? Are you kidding me. Thats why threads of this nature are never aerodynamic because they always leave lots ruffled feathers in thier wake. Thats were the real "drag coefficients" come into play here. This is one area where the "K.I.S.S." strategy never seems to be applied

Truth is if a couple of miles per gallon are going to matter you can't afford the trip. Just think what would happen if the wind changed directions.............

[artwebb]

The reason a rain drop is shaped as it is is that that shape, including the (relatively) long, tapered tip IS the path of least resistance through the air, and rain still falls in drops in a high wind. The same is true of the teardrop trailer. In fact, the drag coeficient of most vehicles is hugely affected by the big low presure areas behind them. The tapered tail of a tear may actualy improve the aerodynamics of some TV's, as the air is more gradualy rejoined behind the combination. And asserting that areodynamics has no effect on 'dirty' air is rediculous. It's still air, and the shape of your vehicle still affects how it moves around your vehicle. Disturbing air does not cancel out aerodynamics, any more than it cancels any other law of physics. Try trading your Tear for a flatbed with a flat front wall (like a log hualer) the same size if you don't believe it.

[PaulC]

The reason a rain drop is shaped as it is is that that shape, including the (relatively) long, tapered tip IS the path of least resistance through the air, and rain still falls in drops in a high wind. The same is true of the teardrop trailer. In fact, the drag coeficient of most vehicles is hugely affected by the big low presure areas behind them. The tapered tail of a tear may actualy improve the aerodynamics of some TV's, as the air is more gradualy rejoined behind the combination. And asserting that areodynamics has no effect on 'dirty' air is rediculous. It's still air, and the shape of your vehicle still affects how it moves around your vehicle. Disturbing air does not cancel out aerodynamics, any more than it cancels any other law of physics. Try trading your Tear for a flatbed with a flat front wall (like a log hualer) the same size if you don't believe it.

A rain drop falls through the air, gravity and air pressure are responsible for it's shape. You are correct with the tapered tail being efficient. Could you show me where the 4' gap in the rain drop is to show me the relevant comparison to a self propelled vehicle towing a TD at 90 degrees to the gravitational pull we experience.

Disturbing the air continuously does affect the drag on the TD. The TD is continually being asked to push through a hurricane.

Paul

[bobhenry]

aerodynamics is overrated





"aerodynamic as a barn"

[Woody]

aerodynamics is overrated

Again I rest my case, point proven and now the rest is will be forever lost in the archives anyway. Just when ya thought it was safe too :lol

[Miriam C.]

aerodynamics is overrated





"aerodynamic as a barn"

You know there is just something I just like about that barn....

I sincerely hope an argument doesn't happen here. We love new and relevant information. Just remember that an opinion is just that and until someone wastes the money to do real drag test we all have one.

btw---Andrews credentials are pretty darn good.

[Ageless]

Last summer; made a three trip thru the southwest. On the level the Ranger dropped maybe 2 mpg. It was gravity that was the real killer; on therrun up the Rockies; I might lose 4 - 5. Now coming back down; I got better mileage than I would even without the trailer

[artwebb]

The reason a rain drop is shaped as it is is that that shape, including the (relatively) long, tapered tip IS the path of least resistance through the air, and rain still falls in drops in a high wind. The same is true of the teardrop trailer. In fact, the drag coeficient of most vehicles is hugely affected by the big low presure areas behind them. The tapered tail of a tear may actualy improve the aerodynamics of some TV's, as the air is more gradualy rejoined behind the combination. And asserting that areodynamics has no effect on 'dirty' air is rediculous. It's still air, and the shape of your vehicle still affects how it moves around your vehicle. Disturbing air does not cancel out aerodynamics, any more than it cancels any other law of physics. Try trading your Tear for a flatbed with a flat front wall (like a log hualer) the same size if you don't believe it.

A rain drop falls through the air, gravity and air pressure are responsible for it's shape. You are correct with the tapered tail being efficient. Could you show me where the 4' gap in the rain drop is to show me the relevant comparison to a self propelled vehicle towing a TD at 90 degrees to the gravitational pull we experience.

Disturbing the air continuously does affect the drag on the TD. The TD is continually being asked to push through a hurricane.

Paul

I did not say the air being disturbed had no effect, I said it does not cancel the aerodynamic advantage of the shape. The tear will still do a better job of moving through this disturbed air than another shape will. And the direction a vehicle moves relative to gravity has no effect on aerodynamic properties. A wind tunnel doesn't drop vehicles straight down, either, but is used to judge forms aerodynamicaly with great success. Gravity has a negligible afect on the aerodynamics of a form, if you dropped water in an environment with gravity but no air, the water would not be tear shaped, it would fall in some haphazard form. It is wind resistance to the water trying top move through air that forms the teardrop shape. A tractor trailer rig is a broken form, and the use of aerodinamic streamlining on them (those tall curved air deflectors on the cabs, in this case) has a major effect on their fuel milage at hiway speed. Granted, this isn't the same as a tear shaped trailer, but it shows that the use of streamlining DOES work on towed vehicle/ tow vehicle combos. Using your reasoning, no streamlining would make any differance at all, simply becuase 'the gap negates the effect'. Some of the trailer manufacturers have started putting curved forms on the front of the trailers, too. And what about the V shaped noses on cargo trailers? Are you going to say that makes no difference, either? I bet some of the corgo conversion guys would beg to differ, especialy the ones who've had both. And Bob not caring about aerodynamics? Then why the 'let in bracing' ? If aerodynamics is BS, why structuraly brace your box against moving air?

[bobhenry]

And Bob not caring about aerodynamics? Then why the 'let in bracing' ? If aerodynamics is BS, why structuraly brace your box against moving air?

HEY it was a bad joke , I really am on your side !

I would like to go on record as saying let in wind bracing is just that , wind bracing. It is utilized to negate the effect of the slab sided nose of the barn in the wind. It is not there in any manor for aerodynamics. It is there BECAUSE of the lack of aerodynamics.

Yes I have pulled the barn with my little 4 cylinder Suzuki in a 35 mile head wind and yes I had to downshift to 4th to keep it moving forward. But that is equal to towing at 85 miles an hour. I drive the roads less traveled when traveling to gatherings and 55 MPH is about max.

I built the barn as a slouchy ( a standie ya gotta duck in) but I can put my pants on inside

I wanted the cube of a cargo trailer ( Cargo envy caused by "Scuba's trailer)

I took my stance to difuse the intense overthinking that was entering into the thread. While I applaude the efforts it realy starts to mess up the minds of new builders. Overthinking the plan takes a lot of the fun out of building. The deer in the headlights panic that freezes a new builder into an abject fear that causes NO progress on a build for fear of making a mistake.

I went back to look into your album to see your efforts in your builds. Thought I might learn from the master. I intend to build my 5th tiny trailer as a 4x8 light weight cross country tear that I can tow easily with the XB or the Esteem I was disheartened that your album is lacking any good examples.

[artwebb]

Anything but the master, Bob, but the point about the let in bracing was exactly as you stated, that the let in bracing was to counteract the massive air pressure (aerodynamic force) of an unaerodynamic design. You are right this thread is over thought a bit, the reverse tear that prompted the discussion is probably very close to a tear in aerodynamics, and no trailer that's close to the same height as the TV is all THAT big a boo, but aerodynamics does have it's effects.
I wish I could remember what show it was I once saw,where they had a major dicussion of vehicular aerodynamics, and used scale models in a small wind tunnel to show air's reaction to various vehicle shapes, as well as combination vehicles, aircraft, oversized vehicles, etc. but that's lost in my younger days, but the question of disturbed air was breifly touched on, the consensus being that the dirty air is still air, and the aerodynamics of a vehicle do matter, even in dirty air.
Perhaps new research has emerged to refute this, but I've not heard of it. anyway, I've stood on my soapbox enough, I'll shut up now.
By the way, I LIKE the barn, and give it a 'Major Cool' and a big thumbs up

[Arne]

http://www.awardrv.com/products_overview.htm