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#1
Old 10-03-2005, 03:41 PM
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Pointing a 15-million Candlepower Flashlight at an Airplane

First of all, don't. It's illegal, dangerous and insanely stupid, especially in this day and age. I only ask this question because someone will eventually conduct this experiment "in the field," and end up talking to the feds. Also because it's one of those intriguing what-ifs. FTR, I have no intention of doing the following, nor would I want anyone else to do so.

That said, as purely a hypothetical, just how bright would the beam of one of those 15-million candlepower flashlights appear in the cockpit of, say, a Lear jet cruising at 40,000 feet?

We're talking cloudless evening, no ceiling. I suppose we're also accepting the eyebrow-raising claims of the flashlight's manufacturer re: 15-million candlepower.
#2
Old 10-03-2005, 03:45 PM
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A final caveat: Some guy in NJ? tried doing something like this about a year ago and was promptly arrested.

Okay, now that I've issued every possible precaution, I hope the Moderators will trust other posters to act sensibly.


Sheesh.
#3
Old 10-03-2005, 04:04 PM
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Not much would happen.

Having flown through (probably) more powerful spotlights (and many of them at once), at ~2000 feet above ground, I can honestly say that it doesn't do anything.

I flew over the CNE in Toronto at night, when they have the spotlights up and circling... Didn't affect me at all... Actually, it was quite fun.
#4
Old 10-03-2005, 04:05 PM
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Quote:
Originally Posted by Carnac the Magnificent!
I suppose we're also accepting the eyebrow-raising claims of the flashlight's manufacturer re: 15-million candlepower.
I'll leave the rest to other with more knowledge, but allow me to address this. That figure is almost certainly beam candlepower, which is the amount of output a bare, unfocused light source would need to have to provide the same illumination at a given point from the same distance. The actual total light output of the flashlight will be much lower, probably just a few thousand candlepower (more often called candelas these days).
#5
Old 10-03-2005, 04:08 PM
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Apparently, this 15-million candlepower light can be seen about 6 miles away. My calculations put that at about 31,000 feet. So a learjet flying at 40,000 feet won't be able to even see it. At about half that height, I imagine it would be visible, but probably not blinding.
#6
Old 10-03-2005, 04:18 PM
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This is absurd -- you can see ordinary streetlamps when you're flying at altitude, both incandesc ent and sodium vapor lamps. I'll bet they're not even close to the outputs you're talking about here. You'd certainly see a 15 million candlepower light. But I'm too busy (and lazy) to do any calculations right now.
#7
Old 10-03-2005, 04:30 PM
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Quote:
Originally Posted by Jayrot
Apparently, this 15-million candlepower light can be seen about 6 miles away. My calculations put that at about 31,000 feet. So a learjet flying at 40,000 feet won't be able to even see it. At about half that height, I imagine it would be visible, but probably not blinding.
I think that might have gotten mangled in translation. You can see even not very bright lights at six miles plus under good conditions. Climb a local hill sometime and look for automobiles and house windows. This site claims you can see a 100 candlepower light at 20km at night. I'm guessing that either the claim is meaningless or they mean something like "will perceptibly illuminate something at a distance of six miles".

Anyway, think of the OP this way. An airplane's landing light seems to be about 150 Watts and modern ones use High Intensity Discharge lamps. That's a bit more juice than your 15-million candlepower lantern, but not an order of magnitude more. And, based on frequent empirical observation, an airplane landing light, even when they're much lower than 40K feet, isn't going to blind anyone on the ground. At worst, they'll think they're seeing a planet or a UFO.

Shining such a flashlight at a plane at a close distance (or using, as in the case of the NJ idiot, a laser pointer) might conceivably distract or blind the pilot. But you'd have to be pretty close.
#8
Old 10-03-2005, 04:46 PM
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I found this item about a guy in NJ who shone a green laser pointer (the kind often used by star-gazers) into the cockpit of a small plane and a helicopter, and blamed his daughter when questioned. Is this the same as the 15 million candlepower flashlight in the OP? It seems like quite a different animal to me.
#9
Old 10-03-2005, 04:52 PM
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Quote:
Originally Posted by Jayrot
Apparently, this 15-million candlepower light can be seen about 6 miles away. My calculations put that at about 31,000 feet. So a learjet flying at 40,000 feet won't be able to even see it. At about half that height, I imagine it would be visible, but probably not blinding.
I think that might have gotten mangled in translation. You can see even not very bright lights at six miles plus under good conditions. Climb a local hill sometime and look for automobiles and house windows. This site claims you can see a 100 candlepower light at 20km at night. I'm guessing that either the claim is meaningless or they mean something like "will perceptibly illuminate something at a distance of six miles".

Anyway, think of the OP this way. An airplane's landing light seems to be about 150 Watts and modern ones use High Intensity Discharge lamps. That's a bit more juice than your 15-million candlepower lantern, but not an order of magnitude more. And, based on frequent empirical observation, an airplane landing light, even when they're much lower than 40K feet, isn't going to blind anyone on the ground. At worst, they'll think they're seeing a planet or a UFO.

Shining such a flashlight at a plane at a close distance (or using, as in the case of the NJ idiot, a laser pointer) might conceivably distract or blind the pilot. But you'd have to be pretty close.
#10
Old 10-03-2005, 05:00 PM
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Quote:
Originally Posted by h.sapiens
I found this item about a guy in NJ who shone a green laser pointer (the kind often used by star-gazers) into the cockpit of a small plane and a helicopter, and blamed his daughter when questioned. Is this the same as the 15 million candlepower flashlight in the OP? It seems like quite a different animal to me.
Fark has that flashlight yesterday and one of the "flashlight geek" sites the discussion pointed out that the "15 MILLION CANDLEPOWER" spec is pretty questionable in terms of useful light. The "headlights" most airplanes have mounted on the fuselage and use pretty regularly are orders of magnitude more powerful than that flashlight in terms of real world light output.

Even if you pointed it at an airplane 1000-2000 feet up it would spread and diffuse like crazy before it hit the plane. A much weaker laser that would stay focused onto smaller area is a lot more worrisome.
#11
Old 10-03-2005, 05:31 PM
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Quote:
Originally Posted by astro
Fark has that flashlight yesterday and one of the "flashlight geek" sites the discussion pointed out that the "15 MILLION CANDLEPOWER" spec is pretty questionable in terms of useful light. The "headlights" most airplanes have mounted on the fuselage and use pretty regularly are orders of magnitude more powerful than that flashlight in terms of real world light output.

I've heard a couple of guys claim that their $39.95 Costco-brand 10-million candlepower flashlight is as bright as ... (drum roll) ...

A lighthouse.

One even compared the rating for his with those flashlights that are found on Mississippi-River barges.


BTW, I've read that police helicopters carry search lights rated at roughly 20 million candlepower, but the diameter of the beam is about 20 inches, compared to the 7-inch beam courtesy of Costco. In short, I'm guessing the police are equipped with a somewhat more powerful light than my friend.
#12
Old 10-03-2005, 05:34 PM
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Quote:
Originally Posted by h.sapiens
I found this item about a guy in NJ who shone a green laser pointer (the kind often used by star-gazers) into the cockpit of a small plane and a helicopter, and blamed his daughter when questioned. Is this the same as the 15 million candlepower flashlight in the OP? It seems like quite a different animal to me.

Yes, the NJ guy--that would be the guy who blamed his kid--pointed a handheld laser at an airplane's cockpit, which is about as dumb as you can get.

I'm talking about a flashlight. A BIG flashlight, but still battery-powered and quite portable.
#13
Old 10-03-2005, 05:46 PM
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The light at the top of the Luxor hotel in Las Vegas is described as 40 billion candlepower. AFAIK, no pilots flying into the very nearby airport have been harmed by it, although it was apparently rather distracting, so it's been dimmed somewhat. Regardless, it's still described as the brightest light on the planet.
#14
Old 10-03-2005, 08:29 PM
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Quote:
Originally Posted by Carnac the Magnificent!
First of all, don't. It's illegal, dangerous and insanely stupid, especially in this day and age. I only ask this question because someone will eventually conduct this experiment "in the field," and end up talking to the feds. Also because it's one of those intriguing what-ifs. FTR, I have no intention of doing the following, nor would I want anyone else to do so.

That said, as purely a hypothetical, just how bright would the beam of one of those 15-million candlepower flashlights appear in the cockpit of, say, a Lear jet cruising at 40,000 feet?

We're talking cloudless evening, no ceiling. I suppose we're also accepting the eyebrow-raising claims of the flashlight's manufacturer re: 15-million candlepower.
Your caveat would apply to lasers, even the small hand held kind, but not to a light with a spread beam.
#15
Old 10-04-2005, 03:53 AM
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I was under the impression that the guy in NJ had, not an ordinary >.5 milliwatt green laser, but a much more powerfull version. I once saw a website claiming to have up to 100 milliwatt green pointers for sale, but not legaly in the US. the site included video of a 25 milliwatt handheld green cutting through electrical tape. I will see if the site is still around.
#16
Old 10-04-2005, 04:38 AM
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http://amazing1.com/laser_pointers.htm

Second one down is a 100 milliwatt laser. Runs on c cells. Now that would do some damage pointed at a plane. So don't.
#17
Old 10-04-2005, 09:34 AM
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Quote:
Originally Posted by CalMeacham
This is absurd -- you can see ordinary streetlamps when you're flying at altitude, both incandesc ent and sodium vapor lamps. I'll bet they're not even close to the outputs you're talking about here. You'd certainly see a 15 million candlepower light. But I'm too busy (and lazy) to do any calculations right now.


C'mon, do it for science!
#18
Old 10-04-2005, 12:18 PM
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I've heard these stories, but the laser pointer and the flashlight ones and I'm having trouble believing any of them.

How the heck does someone standing on the ground shine a light into the cockpit of a flying airplane?

Unless you are standing on a cliff or a very tall building, you are going to be BELOW the airplane. Last I saw, airplane do not have windows in the floor of the cockpit. Just how are these people claiming that they managed this?
#19
Old 10-04-2005, 01:07 PM
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Quote:
Originally Posted by Tastes of Chocolate
Unless you are standing on a cliff or a very tall building, you are going to be BELOW the airplane. Last I saw, airplane do not have windows in the floor of the cockpit. Just how are these people claiming that they managed this?
That's another factor people have been ignoring. You can see down out of the windshield of an airplane, but not straight down. In level flight, IIRC, you can see down at about a 45 degree angle. That means if the plane is at 40,000 feet altitute, you'd have to be 40,000 feet in front of it, so your beam would actually be traveling over 56,500 feet, or almost 11 miles.

My son has aimed one of those bright flashlights at me when I was only a few hundred yards away, and I was nowhere near blinded. Messed up my night vision a tad, but I could see again in the moonlight after blinking a few times and waiting a few seconds.
#20
Old 10-04-2005, 05:04 PM
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IIRC, it was done on short approach and there are a lot of places where you have a clear and close shot at the cockpit of airliners just before touch down. And that is a real bad time to make the pilots have to blink and rub their eyes for 15 seconds or so........

If you have ever used a signial mirror, you will find it is easier than you would think to flash across where you want it....

Those strong green lasers are bad news for pilots.........
#21
Old 10-04-2005, 10:07 PM
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I was talking about flashlights at 40,000 feet, GusNSpot, not lasers on approach. I was responding to the OP.
#22
Old 10-04-2005, 10:58 PM
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What on earth could possibly justifly a 15 million CP flashlight?
#23
Old 10-05-2005, 01:24 AM
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Quote:
Originally Posted by adam yax
What on earth could possibly justifly a 15 million CP flashlight?
Testosterone. I eagerly await its arrival at Costco. I find their current 10m candlepower offering to be insufficient.
#24
Old 10-05-2005, 01:37 AM
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Quote:
Originally Posted by adam yax
What on earth could possibly justifly a 15 million CP flashlight?
When I hear noises at night, I want a flashlight that can light up my livestock at the far end of the pasture (about 1/4 mile away) to make sure they're okay.
#25
Old 10-05-2005, 02:33 AM
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Quote:
Originally Posted by adam yax
What on earth could possibly justifly a 15 million CP flashlight?
Handheld tanning? Cooking with a flashlight? Looking into the beam to see those cool floaty blobs? Handheld Bat signal? Hair drying without the blowing? Finaly showing those snotty candles a thing or two? Too cheap for xrays on that broken hand?

The list goes on and on.
#26
Old 10-05-2005, 09:33 AM
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Quote:
Originally Posted by CynicalGabe
Testosterone. I eagerly await its arrival at Costco. I find their current 10m candlepower offering to be insufficient.

If testosterone is driving your purchases, you might want to go with these TWO-BILLION CANDLEPOWER KLIEG LIGHTS.

See: "Dancing in the Streets"

http://historylink.org/essays/ou...m?file_id=3753

disclaimer: Not sure if 2 Billion is aggregate candlepower, or individual. Either way, don't stare into the beam. It could melt your head.
#27
Old 10-05-2005, 01:36 PM
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Quote:
Originally Posted by Carnac the Magnificent!
If testosterone is driving your purchases, you might want to go with these TWO-BILLION CANDLEPOWER KLIEG LIGHTS.

See: "Dancing in the Streets"

http://historylink.org/essays/ou...m?file_id=3753

disclaimer: Not sure if 2 Billion is aggregate candlepower, or individual. Either way, don't stare into the beam. It could melt your head.
I'm there!
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