Brims & Bernoulli's Principle

[AlterEgo]

Bernoulli's principle states that the higher the speed of a flowing fluid or gas, the lower the pressure.

It's this principle that explains the lift of an aircraft wing. An airplane wing is shaped so that the speed of air on top is greater than the speed of the air below. This means that the pressure of the air below the wing is greater than the pressure on the top surface, and the air exerts an upward force.

My theory is that Bernoulli's principle is at least partially responsible for hats with wing-shaped brims taking flight. Yes, I know that wing/brim surface area, speed, drag, and angle of attack all have an effect on lift, but here's my case:

I just got an Akubra Lawson. It has a 3-inch brim turned down in front and back, making a gently sloping downward arch--somewhat like an airplane wing. This hat fits with the same snugness as all my other Akubras, but I've never had a hat that flies off my head so readily.

It's also my first hat with this shape of brim. The brims of my Sydney/Fedora, Stylemaster, and Fed IV Deluxe all turn down in front and up in the rear. It takes a pretty stiff wind to blow them off my head.

The brim of my Aussie Military Slouch, when I fold it down from the jaunty side-up position as I always do in intense sun and downpours, is virtually flat. In similar wind, it is much less likely to fly off my head than the new Lawson, even though the Slouch has an even wider brim, nearly 3 1/2 inches.

So, am I on to something here?

 

[dhermann1]

I think I'm unconsciously flying the wing of my brim when the wind kicks up. You learn the correct angle of incidence very quickly. Maybe I'm Sally Field's uncle and don't know it.

 

[Yeps]

my Stetson St. Regis, the brim of which is shaped as more of an upside down airfoil, actually presses itself down onto my head when the wind blows.

 

[frussell]

Rigidity

Some of this, in my personal experience, has more to do with brim rigidity than shape. I ride horses fairly often in a windy section of desert canyons, and hate like hell to have my hat come off. Straw hats tend to fly off more commonly for me, as do newer, stiffer felt hats. I find that if a hat has been broken in, or exposed to water, the brim will bend rather than take the updraft and fly. Then again, maybe you're not holding your mouth right. Frank.

 

[150719541]

that´s right

Bernoulli's principle states that the higher the speed of a flowing fluid or gas, the lower the pressure.

It's this principle that explains the lift of an aircraft wing. An airplane wing is shaped so that the speed of air on top is greater than the speed of the air below. This means that the pressure of the air below the wing is greater than the pressure on the top surface, and the air exerts an upward force.

My theory is that Bernoulli's principle is at least partially responsible for hats with wing-shaped brims taking flight. Yes, I know that wing/brim surface area, speed, drag, and angle of attack all have an effect on lift, but here's my case:

I just got an Akubra Lawson. It has a 3-inch brim turned down in front and back, making a gently sloping downward arch--somewhat like an airplane wing. This hat fits with the same snugness as all my other Akubras, but I've never had a hat that flies off my head so readily.

It's also my first hat with this shape of brim. The brims of my Sydney/Fedora, Stylemaster, and Fed IV Deluxe all turn down in front and up in the rear. It takes a pretty stiff wind to blow them off my head.

The brim of my Aussie Military Slouch, when I fold it down from the jaunty side-up position as I always do in intense sun and downpours, is virtually flat. In similar wind, it is much less likely to fly off my head than the new Lawson, even though the Slouch has an even wider brim, nearly 3 1/2 inches.

So, am I on to something here?

yes, the Bernoulli´s principle is used in car´s races with spoilers and brims, also in mi job (swimming coach) it play an important help in stroke swim mechanics, if you use this principle mixed with fluid mechanics principles. The different brim position in hats have a great importance to cut wind.

 

[Stan]

Hi,

Yes, I also tilt my head in the wind such that it causes the airflow to push a hat onto my head as opposed to lifting it off. It's second nature, actually. I guess that means I've worn hats for too many years! [huh]

later!

Stan

 

[AlterEgo]

Oh, yes, I've been wearing brimmed hats since I was a kid and well know the fine art of cocking my head just so to keep the wind from blowing them off.

Yet, my new Lawson takes flight like no other hat I've ever owned, even though I've softened up the felt to take much of the initial stiffness out. Its airborne proclivity is the only thing I don't like about it, but it's a significant annoyance because I got the hat specifically to do outdoor activities in--walking, hiking, shooting, yard work--all of which are things that take quite some time. So, I'm constantly distracted from the task at hand by having to reach up and grab the brim before it flies off.

I posted another thread on getting a chin strap for it. My Aussie Military Slouch is the only hat I've ever had with one, but if I cinch it up tight enough to keep the hat on my head in a stiff wind, the stampede string itself is an irritant on my chin and alongside the sides of my face. Compared to the Lawson, this hat, however, stays on my head much better in similar wind conditions, so I rarely use the strap.

Which brings me back to Bernoulli's principle. I know there are members here who are pilots. What do y'all think?

 

[Sam Craig]

This is all very interesting, but out here where it's really windy all the time, there is only one real answer

Surgical screws

You have them implanted in your skull and use a lock fastener

When you buy a new hat, you simply have the matching link installed in the liner or the sweat ... there are different tasts as to placement ... and then you latch that hat in when you put it on

The original expense is fairly high, but the cost per hat for the fasteners isn't too bad and it's well worth the insurance.

Hope that helps,

Sam

 

[Bill Greene]

This is all very interesting, but out here where it's really windy all the time, there is only one real answer

Surgical screws

You have them implanted in your skull and use a lock fastener

When you buy a new hat, you simply have the matching link installed in the liner or the sweat ... there are different tasts as to placement ... and then you latch that hat in when you put it on

The original expense is fairly high, but the cost per hat for the fasteners isn't too bad and it's well worth the insurance.

Hope that helps,

Sam

My God that's brilliant! I'm calling my local surgeon today!

 

[Andykev]

For every action there is an equal and opposite reaction.

In addition....there is a law of "equal and opposite reaction"..we all learned in science.

Like a gun recoil, or placing your palm out the car window while driving..

The wind or force exerts said energy against the brim of the hat, which lifts back in reaction. It blows off your head.

Don't think aircraft wing design comes into play here...just like the wind blows the leaves or the branches. Hold on to your hat!

 

[StetsonHomburg]

Bernoulli's principle states that the higher the speed of a flowing fluid or gas, the lower the pressure.

It's this principle that explains the lift of an aircraft wing. An airplane wing is shaped so that the speed of air on top is greater than the speed of the air below. This means that the pressure of the air below the wing is greater than the pressure on the top surface, and the air exerts an upward force.

My theory is that Bernoulli's principle is at least partially responsible for hats with wing-shaped brims taking flight. Yes, I know that wing/brim surface area, speed, drag, and angle of attack all have an effect on lift, but here's my case:

I just got an Akubra Lawson. It has a 3-inch brim turned down in front and back, making a gently sloping downward arch--somewhat like an airplane wing. This hat fits with the same snugness as all my other Akubras, but I've never had a hat that flies off my head so readily.

It's also my first hat with this shape of brim. The brims of my Sydney/Fedora, Stylemaster, and Fed IV Deluxe all turn down in front and up in the rear. It takes a pretty stiff wind to blow them off my head.

The brim of my Aussie Military Slouch, when I fold it down from the jaunty side-up position as I always do in intense sun and downpours, is virtually flat. In similar wind, it is much less likely to fly off my head than the new Lawson, even though the Slouch has an even wider brim, nearly 3 1/2 inches.

So, am I on to something here?

Sounds Crazy but I think it is true, I studied Bernoulli's Principal last year

 

[Mikey P]

Warning, obscure TV reference....

Otherwise known as the "Sister Bertrille" effect.

 

[AlterEgo]

OK, everybody, I finally got up with an expert to weigh in on this issue. He's not only an instrument-rated pilot, but also a former flight instructor for British Airways. He also has his own vintage two-prop plane.

When I posited my theory to him that Bernoulli's principle is partially responsible for hats with wing-shaped brims taking flight--demonstrating by snapping down the rear of the brim of the Stylemaster I was wearing that day--he said, "Well, of course," looking back at me with a duh-you-idiot! look.

Even so, he agreed to help me perform some experiments. So, with a passel of my hats in tow, we headed out to the hangar at the local air field where he keeps his plane.

For wind, he started the plane and let the engines idle until they were steady. With him inside the plane at the throttle to adjust prop speed, I stood outside about fifteen feet behind one engine changing hats while holding a little gadget of his that measures wind speed next to my temple. Since we were alone inside the giant hangar, the props were the only source of wind, and they provided the steady--not gusting--sort.

I'll save "wind" here by skipping to the results:

My new Lawson, with its wing-shaped, curved-down-in-front-and back 3-inch brim was, in fact, by far the easiest hat to fly of my head. It only took a 9 to 10 mph wind before it flew off. My walking speed is 5 mph; add just 4 or 5 mph headwind, and no wonder it blows off so readily!

Next, was the Akubra Military Slouch, with its almost 3 1/2-inch brim turned down virtually flat all around, flying off at 12 to 13 mph. (With the brim turned up and fastened on the side, it stayed on until 15 to 16 mph.)

Third place was a tie between my Stylemaster, which has a 2 1/2-inch snapped-down-in-front, snapped-up-in-back brim, and my Federation IV Deluxe, having a 2 7/16 (sides) by 2 3/4 (front/back) dimensional brim I've fashioned into a somewhat hard front downturn and gentle rear up-curve. These two hats took off at 14 to 15 mph.

Of the five fur felts I brought along--all fitting my head the same and with similar crown heights--the Sydney/Fedora was the least likely to make like bird, staying on until wind speed reached 16 to 17 mph, even though its 2 1/2-inch brim is the same width and shape as the Stylemaster's..

I can only explain this by the Sydney's felt's being so extremely soft and pliable that it flexes out of the way, effective reducing the surface area the wind has to push against, before it finally blows off. Since the Stylemaster and Fed IV results were the same, even though the Fed's brim is wider, likewise, the probable reason is its significantly softer brim felt flexes more before taking flight. These findings confirm Frank Russell's earlier assertion that stiffer hats are more likely to blow off.

No, I did not tote all 80 of my lids for testing, but I did bring along a few other hats for fun.

An ivy style suede and tweed cap blew off at a relatively low 11 to 12 mph, but this particular cap sits high on my head, is very lightweight, and fits large, so one cannot extrapolate this test to ivies at large. So, continue to wear your ivy as you motor about in your old MG.

My baseball caps, most of which have about a 2 3/4 bill as measured top dead center, stayed on until the low-30-mph range. Interestingly, the one with the most curve to the bill was the most wind-resistant, staying put until almost 40 mph.

My vintage unlined, unbanded Beret Industries Ltd 10 3/8-inch-diameter beret (described near the beginning of NonEntity's (AKA my) "Berets, Anyone?" thread) would not blow off. I'm sure it eventually would, but, despite its wheels being chocked, the plane began to move, and since flying inside the hangar would have been a challenge even for the seasoned flight instructor, we aborted the test.

In a world of unlimited time and patience--particuarly that of my pilot acquaintance--I would have liked to test some other hats, namely, some straws and a pith helmet, as weight is certainly a major blow-off factor.

However, for now, I'm satisfied that our little experiment proved Bernoulli's principle, brim width, and felt stiffness are all elements that factor into the "blow-off-ablilty" of a hat.

With this information, you are now cleared to buy another hat!

 

[Speedbird]

Please tell me you did video this experimental hat science in action and posted to You Tube???

You did ... didn't you?

 

[Woodfluter]

Cool beans, AlterEgo!

I'm glad you could do the experiment. I have found pretty much the same as you, by experience. Long, long ago (won't say how long, but college age) I liked to wear hats with brim down all around, and thought that looked nice. But I had this blow-off issue.

Later I worked one of these into a turned-up back for some trivial reason, probably some photo I saw in an old book, and much to my surprise it stayed on far better.

I'm long familiar with Bernoulli's principle from fluid mechanics. I thought about that but just didn't believe it could apply to any significant degree to hats because of all the variables - angle at which wind is blowing, influence of crown on airflow and turbulence, angle of wearing the hat...but you can't argue with the results.

When I got a Lightning Ridge Akubra last year, quite similar in shape to your Lawson, the very first thing I did was steam in a turned-up back, plus a slight semi-pencil roll back there. Hasn't been an issue in wind.

Honestly, I have trouble believing this is a factor but it really seems to be!

All the best,
- Bill

 

[John in Covina]

This is all very interesting, but out here where it's really windy all the time, there is only one real answer

Surgical screws-You have them implanted in your skull and use a lock fastener
When you buy a new hat, you simply have the matching link installed in the liner or the sweat ... there are different tasts as to placement ... and then you latch that hat in when you put it on The original expense is fairly high, but the cost per hat for the fasteners isn't too bad and it's well worth the insurance. Hope that helps, Sam

How about under the skin magnets?

 

[Yeps]

How about under the skin magnets?

They have the added bonus of protecting you from the government mind control waves.

 

[scottyrocks]

This is all very interesting, but out here where it's really windy all the time, there is only one real answer

Surgical screws

You have them implanted in your skull and use a lock fastener

When you buy a new hat, you simply have the matching link installed in the liner or the sweat ... there are different tasts as to placement ... and then you latch that hat in when you put it on

The original expense is fairly high, but the cost per hat for the fasteners isn't too bad and it's well worth the insurance.

Hope that helps,

Sam

That Frankenstein guy got it all wrong. He put em too low! No wonder the monster was always POed. He couldnt keep his hat on.