Comments on: DEFY S. McQUAID! #74: Rain and the speeding automobile http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/ It's hard being a superstar Fri, 05 Dec 2008 03:38:06 +0000 http://wordpress.org/?v=2.2.2 By: mike d. http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-75208 mike d. Wed, 12 Mar 2008 12:41:38 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-75208 So I decided to do some math to try and put this to rest. I'm not sure Mr. McQuaid is completely accurate in his breakdown. First lets look at logic with the MSPaint that SMcQuaid alludes to. <a href="http://www.mikedidonato.com/images/2008/03/stay_dry.PNG" rel="lightbox" rel="nofollow">MSPaint</a> In order for Joe Convertible to stay dry, he has to be going fast enough so that the first drop of water that's not blocked by his windshield won't hit him in the head. I took a basic guess with car dimensions and said that he'd have to cover 2 feet in the time it took a drop of water to fall 6 inches. Some additional research leads us to this <a href="http://www.wonderquest.com/falling-raindrops.htm" rel="nofollow">website</a> which tells us that raindrops hit the ground between 5 and 20 mph. This converts to about 87 - 351 inches/second. 6/351 = 0.017 6/87 = 0.069 This means it takes between 0.017 - 0.069 seconds for a raindrop to fall 6 inches. So we have to cover 24 inches in that same time frame in order for Joe to stay dry. What's that come out to? 24"/6" = 4 This means we have to be driving four times faster than the raindrop. With our example, this means that on a typical rainy day Joe Convertible can drive 20-80 mph (32-128 km/h) in order to stay dry. We can expand this to include the whole car by switching to variable analysis. 'y' is the distance the drop must fall 'x' is the full length of the cabin 'v' is the velocity of your raindrop (v*x)/y will give you the speed you need to travel in order to out run the water drops. If your windshield is 24 inches tall, and your cabin is 8 feet long then the math works out the same way. Now, rain never falls straight down. There's an obvious wind factor. But to take this into consideration, just take the speed of the wind in the x direction and add (or subtract) it to the speed of your car. That should do it! So yes, I think it is possible to outrun rain. But you'll be out of luck at your first stop light. So I decided to do some math to try and put this to rest. I’m not sure Mr. McQuaid is completely accurate in his breakdown. First lets look at logic with the MSPaint that SMcQuaid alludes to.

MSPaint

In order for Joe Convertible to stay dry, he has to be going fast enough so that the first drop of water that’s not blocked by his windshield won’t hit him in the head. I took a basic guess with car dimensions and said that he’d have to cover 2 feet in the time it took a drop of water to fall 6 inches.

Some additional research leads us to this website which tells us that raindrops hit the ground between 5 and 20 mph. This converts to about 87 - 351 inches/second.

6/351 = 0.017
6/87 = 0.069

This means it takes between 0.017 - 0.069 seconds for a raindrop to fall 6 inches.

So we have to cover 24 inches in that same time frame in order for Joe to stay dry. What’s that come out to?

24″/6″ = 4

This means we have to be driving four times faster than the raindrop.

With our example, this means that on a typical rainy day Joe Convertible can drive 20-80 mph (32-128 km/h) in order to stay dry.

We can expand this to include the whole car by switching to variable analysis.

‘y’ is the distance the drop must fall
‘x’ is the full length of the cabin
‘v’ is the velocity of your raindrop

(v*x)/y will give you the speed you need to travel in order to out run the water drops.

If your windshield is 24 inches tall, and your cabin is 8 feet long then the math works out the same way.

Now, rain never falls straight down. There’s an obvious wind factor. But to take this into consideration, just take the speed of the wind in the x direction and add (or subtract) it to the speed of your car. That should do it!

So yes, I think it is possible to outrun rain. But you’ll be out of luck at your first stop light.

]]> By: spiro http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-75190 spiro Wed, 12 Mar 2008 02:37:50 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-75190 i have a mercedes, smart car, 2 seater , was going 80-100 klm per hour and i wasnt getting wet! pouring rain , the back part of the car got wet , but me , the front part of the car and the passenger seat.made it clear! my roof broke this afternoon so got trapped out when it started rainning! didnt want to test the theory! , just wanted to share this. i have a mercedes, smart car, 2 seater , was going 80-100 klm per hour and i wasnt getting wet! pouring rain , the back part of the car got wet , but me , the front part of the car and the passenger seat.made it clear! my roof broke this afternoon so got trapped out when it started rainning! didnt want to test the theory! , just wanted to share this.

]]> By: Theresa http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-64806 Theresa Wed, 22 Aug 2007 15:49:03 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-64806 Mr McQuaid is awesome. I love this column. Mr McQuaid is awesome. I love this column.

]]> By: smcquaid http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-64780 smcquaid Tue, 21 Aug 2007 13:53:00 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-64780 The fact that this response is in all caps means it HAS to be true. Right? No, wait, not at all. I've been thinking about this one, and if the windshield is high enough, Old Man Schenk may be right in the possibility that the front seats stay dry, while the rear gets wet. The MX-5, of course, is so small that it doesn't quite have rear seats, so Mister Capital Letters may be correct. The fact that this response is in all caps means it HAS to be true. Right?

No, wait, not at all.

I’ve been thinking about this one, and if the windshield is high enough, Old Man Schenk may be right in the possibility that the front seats stay dry, while the rear gets wet. The MX-5, of course, is so small that it doesn’t quite have rear seats, so Mister Capital Letters may be correct.

]]> By: KRistoph http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-64684 KRistoph Fri, 17 Aug 2007 15:31:39 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-64684 UMMMM YOU GUYS ARE ALL WRONG, I had a MASZDA MX-5 I WITH REAR WIND BLOCKER AND I DROVE THAT CAR HUNDREDS OF TIME IN THE RAIN WEATHER IT BE MISTING OR A RAIN STORM!!!! I ONLY GOT WET FROM THE WATER ATTACHING TO SIDE WINDOWS THEN SWINGING INTO THE SIDE OF THE CAR. UMMMM YOU GUYS ARE ALL WRONG, I had a MASZDA MX-5 I WITH REAR WIND BLOCKER AND I DROVE THAT CAR HUNDREDS OF TIME IN THE RAIN WEATHER IT BE MISTING OR A RAIN STORM!!!! I ONLY GOT WET FROM THE WATER ATTACHING TO SIDE WINDOWS THEN SWINGING INTO THE SIDE OF THE CAR.

]]> By: Jes Saint http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-52386 Jes Saint Tue, 05 Dec 2006 18:06:30 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-52386 That depends on how hard it's raining. That depends on how hard it’s raining.

]]> By: Elby http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-52309 Elby Mon, 04 Dec 2006 15:13:06 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-52309 This can probably be doable but very unlikely to be accomplish. You must realize that you will be driving between raindrops. Not likely. This can probably be doable but very unlikely to be accomplish. You must realize that you will be driving between raindrops. Not likely.

]]> By: Old Man Schenk http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48474 Old Man Schenk Wed, 19 Jul 2006 17:12:27 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48474 In a hard rain, would it be possible to drive a Mini fast enough so that your head doesn't get rained on (but maybe the back seats got wet?)? I think this is possible on a motorcycle with a big <a href="http://www.toymania.com/334archives/chips/cycle1.jpg" rel="nofollow">CHIPS-style windshield</a>. Then again, you are much closer to the windshield on a motorcycle. In a hard rain, would it be possible to drive a Mini fast enough so that your head doesn’t get rained on (but maybe the back seats got wet?)?

I think this is possible on a motorcycle with a big CHIPS-style windshield. Then again, you are much closer to the windshield on a motorcycle.

]]> By: smcquaid http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48471 smcquaid Wed, 19 Jul 2006 15:22:51 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48471 Showers or misting, fine - the aerodynamics (of a Mini, especially) can do it. But a hard rain? Nope. Showers or misting, fine - the aerodynamics (of a Mini, especially) can do it. But a hard rain? Nope.

]]> By: ben http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48468 ben Wed, 19 Jul 2006 13:18:21 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48468 The Mini Convertible has mentioned this endlessly, you can outrun rain at about 50+.... there was even a flash animation. While I've not tested it myself, it's hard to argue with a convinving flash animation. The Mini Convertible has mentioned this endlessly, you can outrun rain at about 50+…. there was even a flash animation. While I’ve not tested it myself, it’s hard to argue with a convinving flash animation.

]]> By: Aaron http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48457 Aaron Tue, 18 Jul 2006 17:24:34 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48457 Here's my thought: let's assume it's a short-bodied convertible, like a Miata or a TT. Maybe a 2 foot drop fromthe top of the windshield to the top of the door, and thus, the interior of the car (probably giving myself too much room here, but stay with me). Say from the end of the windshield to the end of the passenger compartment is 4 feet. This means that in order to keep from getting hit by the water, you have to travel twice as fast as the terminal velocity of the rain. Right? So, if you can just get some really thick air to drive through, and slow down the rain, you should be able to do it without a shock wave. Here’s my thought: let’s assume it’s a short-bodied convertible, like a Miata or a TT. Maybe a 2 foot drop fromthe top of the windshield to the top of the door, and thus, the interior of the car (probably giving myself too much room here, but stay with me). Say from the end of the windshield to the end of the passenger compartment is 4 feet. This means that in order to keep from getting hit by the water, you have to travel twice as fast as the terminal velocity of the rain. Right? So, if you can just get some really thick air to drive through, and slow down the rain, you should be able to do it without a shock wave.

]]> By: Kurt from Work http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48452 Kurt from Work Tue, 18 Jul 2006 11:55:29 +0000 http://www.mikedidonato.com/2006/07/18/defy-s-mcquaid-74-rain-and-the-speeding-automobile/#comment-48452 hhhhmmmm....Sonic Boom Acclaim.....I see a science experiment when MikeD gets home. hhhhmmmm….Sonic Boom Acclaim…..I see a science experiment when MikeD gets home.

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