That reminds me, the other designs need to be sure to incorporate the threaded head section thus allowing the head to be made from a smaller hunk of metal saving money and allowing easier access to the LED.
I like it a lot. Which file formats can you export? Maybe I could perform a thermal analysis of your model. It would be interesting to know if it maybe performed better than mine.
The 300 lumens per watt is, as far as I understood it correctly, the maximal theoretical value a white led can reach (wikipedia). At this point the led would have a efficiency close to 1 or 1. Now if a led puts out around 150 lumens per watt it would have half the efficiency of a perfect led and consequently around 0.5.
But you are right, the way leds are driven here they are less efficient. But hey, our numbers agree here so it sounds about right. :+1:
Hmm, interesting that it happens to be close but I doubt the 300 lumens per watt is the “perfect led” personally. That claim used to be around 250 lumens per watt IIRC.
Cree has already made a 303 lumen per watt LED and something tells me that LED tech has not maxed out never to be improved again.
The interesting thing is that in a perfect LED with 100% efficiency there would be no heat to get rid of, it would all exit the front of the light carried by the light photons.
The same goes for car engines, if they were to run even 75% (IIRC) efficiency or more they would not need radiators and could be easily cooled by air.
All the latest coatings and tech has sought to bring this about and there is some promising tech out there that could vastly improve things. Although not sure they will ever get THAT good.
The tactical ring was added as an anti-roll device first and strap attachment point second. Although it does give you options for balancing the light in different ways by having both.
If the tailcap switch is removed then the bottom of the light could be made flat and remove the holes there, so nice the have the ring already designed for a secondary strap point ahead of time.
So as far as I understood it from the cpf topic: Lumen is a unit based on the human eye. So one watt of light in green has more lumens than one watt of light in white. So there are different upper limits for different wavelength types. That’s why cree already cracked the 300 lumens per watt. See this table on wikipedia: Luminous efficacy - Wikipedia
Well, just remember that Cree hit the 300 lm/w efficiency at a very low current. So, of course, there can still be improvements just by making the efficiency go up in higher current scenarios. A “perfect” LED would have to be one that could never burn out at any current. If there’s no heat, how could it? So, there is definitely a long way to go still.
Sorry, you’re reading that wrong. Luminous efficacy - Wikipedia
100% luminous efficacy is 683lm with 1W.
The theoretical maximum of an LED is 260-300 which it says right beside is 38.1–43.9 efficiency.
Driving an XHP70 at 12A requires 7.5v, which is 12*7.5=90W. At this current it produces slightly over 5000lm, so you get 5000/90 = 55.6lm/W
If you look on the wikipedia page, in the first chart, 54.7lm/W is 8% efficiency. So basically for the XHP70 7.2W are turning into light, and 82.8W are going into heat.
It says for an LED that 300lm is 43.9% efficiency.
300/0.439 = 683.4lm
So that means an LED working at peak efficiency 300lm/W will only be converting 43.9% of the power into light.
I quote the first sentence in the wikipedia article
So for green the Luminous efficacy is 100%. That means we see green light best. However, we don’t see other wavelengths as good as green. So what we perceive as 683 lm in green, we just perceive as around 300 lm in a different wavelength.
Same number used as fritz15, only the model has changed.
Total time is 600 seconds, time steps are 60 seconds.
(pictures are cross-sections, click for full version)
Here it is with 40 watts:
I feel that Fritz15’s design is most pleasing on the eyes - the most harmonious design - and it has the possibility to mount carrying handel. I really like that.
Not a very big flashlight, but a searchlight.
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Having said that, I could certainly live with 5AR’s design
And a well meant suggestion on that design: the head is, of course, very big and the body relatively small.
No problem, that is the basic design that was agreed upon.
However, it could be made more aesthetically hormonious by adding a much larger tailcap, in which anti-roll could be incorporated, no?
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Just a suggestion, of course :+1:
I think fritz15 is right. The 683lm/W is for 555nm light, and this is practically irrelevant for us because our LEDs are “white”. The luminous efficacy depends on the spectrum, so that efficiency column in the wikipedia article is misleading because it compares every luminous efficacy to that of 555nm light, which hardly relevant.
The 260-300 lm/W value for LEDs is the theoretical maximum given the typical LED spectrum (blue peak and a yellowish peak) and it represents 100% conversion of input power to photons.