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Speed Boat Survival
THIS MYTH WAS FEATURED IN... Episode Title: ---- Original air date: ---- Myth Title: Speed Boat Jump Survival Myth
Last updated:
Mar 10 2008, 12:24 PM EDT by
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Bifurcated Boat
Description: ---- Can a high performance speed boat be cleft by a chanel marker at only 25mph? MythBusters on the bust: ----Tori, Kari, Grant
Last updated:
Mar 13 2008, 2:03 AM EDT by
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Speed vs. Thrust
People get wrapped around the idea the plane will be stationary. What they don’t realize is the fundamental piece to this question occurs to full scale on a daily basis!
Picture yourself on the bank of a river with a radar gun. Coming down the river is a raft; you point your radar gun at the raft and determine that it’s traveling at 10mph down stream; therefore the river is flowing at a rate of 10mph. Down the river you see a speed boat coming up stream… no tires, so again, you use the radar gun to determine its speed. To your surprise it’s moving forward up stream, at a rate of only 10mph. How is that possible? How can it go upstream at 10mph and yet the river is flowing down stream at 10mph? Some would argue that it’s really traveling 20mph, but this is not correct. Yes, it is traveling away from the raft at a rate of 20mph, but this is not the boat’s speed relative to your position on the river bank. THRUST IS NOT SPEED. Speed is distance traveled divided by time.
This brings me to a second point. If speed is defined as distance traveled divided by time, then it begs the question- if the plane is stationary on the conveyor belt, then what is the planes speed? Answer- ZERO Mph; so why would the belt be spinning at all? The belt is supposed to match the speed of the plane, not its thrust. For the belt to spin up to any speed at all, the plane FUNDAMENTALLY HAS TO BE MOVING FORWARD.
Which brings me to a third point. Even if this were a car on a conveyor belt, and the belt matched the cars speed, the car WOULD move forward… the key to this being the conveyor belt matches the speed of the car, and not what is registering on the speedometer (how fast the wheels are spinning). Yes, if the speedometer reads 10mph, and the conveyor belt is spinning at 10mph, the car would be stationary, but its SPEED would be ZERO mph, which negates the question, because the conveyor belt is not matching the SPEED of the car.
Posted:
Feb 8 2008, 8:56 AM EST by
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Myths: S – U
: ---- MYTH: Speed Boat DESCRIPTION: Can the team smash a speed boat clean in two by ramming
Last updated:
May 7 2008, 10:49 PM EDT by
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Myths: A – C
speed-radar-busting tricks, including hanging a disco ball by the rearview mirror, covering the car entirely with aluminum foil, and painting the car
Last updated:
Jun 11 2008, 8:18 AM EDT by
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Episode 77: Birds in a Truck
smash a speed boat clean in two by ramming it into a channel marker at high speed? Highlights of This Episode: Bifurcating
Last updated:
Nov 13 2007, 3:26 PM EST by
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Best cure for chili pepper burn: You missed the boat!
What about cheese? Sour cream? Ice cream? Butter? Olive Oil? Boy, you guys missed the boat on this one. I think you need to do the experiment again, leaving out the toothpaste and Vaseline. (And who ever thought of Vaseline???? Yech!)
Posted:
Nov 25 2007, 6:18 PM EST by
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Episode 95: James Bond Special (Part 1)
deflect a bullet from its course? Myth #2: Propane Tank Peril Can you blow up a propane tank with a bullet? Myth #3: Speed Boat
Last updated:
Mar 9 2008, 6:26 PM EDT by
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Special 8: JAWS Special
Versus Dive Cage Can a great white sharkram a dive cage with enough force to damage or destroy it? Myth #5: Shark Versus Boat Can a great white
Last updated:
Aug 14 2007, 7:07 PM EDT by
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Sinking Titanic
: Small scale tests will suck you down but large boats will not. Busted or Not Busted: ---- Busted Highlights of the bust
Last updated:
Jun 23 2008, 7:08 PM EDT by
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Mythbusters/Top Gear Team Up
Why I Chose Him/Her : Can drive anything on four wheels, a few boats, some planes and always has a snarky comment Myths The Myth : Beating
Keyword tags:
None
Last updated:
Sep 2 2008, 3:43 PM EDT by
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Busted Mythbuster Experiments
? Beat the Radar Detector The MythBusters crew tests several speed-radar-busting tricks, including hanging a disco ball
Last updated:
Feb 13 2008, 10:37 PM EST by
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Plane on conveyor
I have questions regarding this test. First of all a car's indicated speed is produced by gears in the transmission. Thus if the car is moving forward at 25 MPH it is indicated because the speedometer is connected to the transmission. An airplane is different. Its airspeed indicator uses air flowing into the pitot tube. You could blow air into this pitot tube and get an indicated airspeed even without the engine running. If the plane got its speed indicated by the spinning of its wheels, the speed would show 0 once they stopped turning after it took off.
So if the conveyor is moving at 25 MPH in order for the airplane to indicate 25 MPH it HAS to move faster than the conveyor. Perhaps they should have tried this test with a speedometer connected to the planes wheels.
Posted:
Apr 17 2008, 7:13 PM EDT by
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Mythitty Split
I would go further.. If you look at the slow motion video the wheels turned, but hte direction of the boat didn't change.. So not only did you not have the additional resistance, you didn't get any lateral force.. You could make up for the water resistance with lateral force, but they didn't come close to getting side force. They really got exactly the same results as the small scale test they did, so in this case I don't think you could get enough speed to split the boat without some side force on the boat.
Keyword tags:
None
Posted:
Jan 20 2008, 4:53 AM EST by
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You're not my wife, you're a "winch"
People get wrapped around the idea the plane will be stationary. What they don’t realize is the fundamental piece to this question occurs to full scale on a daily basis!
Picture yourself on the bank of a river with a radar gun. Coming down the river is a raft; you point your radar gun at the raft and determine that it’s traveling at 10mph down stream; therefore the river is flowing at a rate of 10mph. Down the river you see a speed boat coming up stream… no tires, so again, you use the radar gun to determine its speed. To your surprise it’s moving forward up stream, at a rate of only 10mph. How is that possible? How can it go upstream at 10mph and yet the river is flowing down stream at 10mph? Some would argue that it’s really traveling 20mph, but this is not correct. Yes, it is traveling away from the raft at a rate of 20mph, but this is not the boat’s speed relative to your position on the river bank. THRUST IS NOT SPEED. Speed is distance traveled divided by time.
This brings me to a second point. If speed is defined as distance traveled divided by time, then it begs the question- if the plane is stationary on the conveyor belt, then what is the planes speed? Answer- ZERO Mph; so why would the belt be spinning at all? The belt is supposed to match the speed of the plane, not its thrust. For the belt to spin up to any speed at all, the plane FUNDAMENTALLY HAS TO BE MOVING FORWARD.
Which brings me to a third point. Even if this were a car on a conveyor belt, and the belt matched the cars speed, the car WOULD move forward… the key to this being the conveyor belt matches the speed of the car, and not what is registering on the speedometer (how fast the wheels are spinning). Yes, if the speedometer reads 10mph, and the conveyor belt is spinning at 10mph, the car would be stationary, but its SPEED would be ZERO mph, which negates the question, because the conveyor belt is not matching the SPEED of the car.
Posted:
Feb 7 2008, 12:31 PM EST by
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Plane on Conveyor- Gross Inaccuracies
Here is my test scenario for this Myth...
Measure the rpms of a motor on a plane at 25mph in flight with no wind. and no landing gear. (resistance). Measure the amount of wind behind the propeller and on the wings at level flight. Use a level!
Take the same plane and electronically set the engine to run at this RPM while
restraining the aircraft from behind and from the front balanced. Loosely attach rubber bands from the bottom of the aircraft and tighten them directly under the center of gravity where lift occurs. This is only to be used to keep other parameters in sync, measure lift, and keep the plane level.
Attach the plane to wheels that are turning at 25mph (conveyor) with release mechanism that breaks from the plane and leaves the entire landing gear behind when everything is ready. Need something to catch them!
Force wind at the plane until the measurements are the same as they where in flight behind the propeller and on the wings.
If this is done correctly then the plane should just rise from its position, slightly because the rubber bands are holding it in place, and keep flying up when released. The bands resistance should actually cause the plane to fall back a little and should be considered in the final calculations. Without providing equal resistance on the ground... Yes the plane will take advantage of the elements and pull forward thus taking off from anything.
A good example is... Planes take off from carriers all the time in the ocean. The boat could be going in the opposite direction and the plane still takes off because it is already moving at the speed of the boat before it adds its velocity by means of the propeller.
This myth is completely busted without adding more elements to its flight characteristics.
Important: Plane must be level... wind measurements must be accurate
This experiment would be very costly unless performed at scale.
Just my two cents... Sparq
Posted:
Jul 27 2008, 6:17 PM EDT by
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Regarding Compressed Air Tank Propulsion - Time for a Revisit?
Not that there ever was an actual "myth" attached to oxygen tank / broken valve experiment (I have witnessed these things becoming "rockets" a few times myself over the years), I liked the methodology...and I liked taking it a step further and trying to use the power of the compressed air to power a boat. Compressed gases have so many different utilities, including that of a rocket pack, etc. it would be more interesting to use this principle of propulsion to power something that does not have to overcome quite so much inertia to get started...and so much friction once underway. A couple of "fun" problems could be utilized. One...utilizing the gas pressure to actually power a screw on a boat (instead of the "direct drive" of blowing air against air or air against water)...might be able get more mechanical force between and the water to get it up to (some) speed. Or, two, mount these bad-boy tanks on something a little more straight-forward and earth bound like a go-cart. Then, have the two (Adam/Jamie) go head to head building the best (fastest). Wheel friction can be overcome rather easily (or easier than water around the hull of a boat). Interesting to see how fast/far they can go on a "tank of gas." Three...could possibly use the air pressure to power a small piston motor (a la a steam motor)...to drive the wheels...and run through same tests (or even uphill)...perhaps coasting and "recharging" when going downhill, etc. All this mainly for fun and as an alternative source of energy. Also, what happens when you combine pressure energy and volatility together (e.g. acetylene) ? Just a thought for a revisit.
Posted:
Jun 23 2008, 1:46 PM EDT by
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How fast does primer cord burn?
I remember the divers used to call the stuff primer cord. I believe the army guys called the same stuff detcord but it did the same job. I remember they used the stuff to remove our starboard prop after it got damaged in a storm. A part of our boat (submarine)came off and hit the propellor. They used a crane with cables attached to the prop and unbolted the prop and wrapped primer cord around the shaft in front of the prop and detonated the cord which then the prop was pushed off the shaft. It saved us from going into drydock to have that job done.
With bill0759,s numbers I went to my computer and got this calculation of 11000 feet per second which came out to about 2.08 miles per second or over 7800 miles per hour air speed which is a little over 9.8 times the speed of sound. So at that speed I could make it from my house in New Hampshire to M5 in San Francisco in about 1/2 hour. I still wonder if detcord or primer cord is the fastest burning stuff around.
Posted:
Apr 12 2008, 2:25 AM EDT by
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1:50 Scale down
In the Killer Whirlpool myth, the trawler was a 1:50 scale model. So to compensate, they scaled down the speed of the whirlpool 1:50 (14 knots at 42 rpm becomes 1 rpm to scale). However, is this a true to scale test? The full sized whirlpool has a recorded vortex diameter of up to 20 feet; scaled down 1:50 that would be about 4.8 inches, but there was no visible vortex at 1 rpm on the show. I am not disputing that the power of the whirlpool itself could not sink a trawler; however, if the trawler was to sail towards the vortex, would the bow of the craft not eventually start to point downwards into the vortex? The models on the show did not have engine power, so they were at the mercy of the current and would most certainly float around the vortex, but never sail directly into it. I am just thinking that if the vortex was big enough, and the barge was to sail directly for the middle, then eventually simple gravity would take over and point the boat downwards. After that, Davy Jones would need a new locker.
Posted:
Feb 1 2008, 8:47 PM EST by
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Cable Myth
While watching this myth being busted, I couldn't help but think of two reasons that the pig was not, to Adam's great dismay, cut in half by the whipsnap effect. The first reason is that the pig was suspended in the air and was able to swing around. Thus, any force applied to said pig, such as, say, that of a whipping cable, would be partially but significantly absorbed by the pig's resulting swinging motion, minimizing the force left to break through the skin. In other words, the tension of the skin would require a higher force to break than would be required to move the pig's mass against gravity. The second reason is that the length of the snapping cableshould, unless I am mistaken, significantly change the force it produces. The longer the cable, the more mass it has and thus the more force it produces when moving at similar speeds. It would be interesting to see this myth revisited with a few changes - namely, anchoring the pig and testing either different cable lengths or adding masses to the snapping end of the cable.
Posted:
Mar 18 2008, 12:35 AM EDT by
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