Yeah, keeping the heat down makes a difference, even at rated current or below. But, the lower you go, the less difference it will make.
How about something like this for fins?
The V angle is all the same, so they can be made in the same way. They sort of resemble those on the SK68, so they should be quick to machine. I moved them a little to keep the outside of the deeper ones from being too narrow.
Just spent few minites and make some calculations (to make youself sure that this fins will increase total host area by 1% or less).
Well is the 1% added where 99% of the heat is? I don't see the relevance of total host area.
Thanks for the sketch!
This would add weight
But at the same time I can imagine that less convection can occur due to less air being between the fins.
Is there an example of a good flashlight that is using this kind of design?
Good point. Heat finning can significantly increase surface area at the hottest parts of the flashlight. I did a quick calculation to estimate this.
2*d*pi*D is approximately the extra surface area of one fin. d is the depth of the fin and D is the outside diameter of the light. This approximation is valid when D is much larger than d.
p*pi*D is the area of a section of the surface of the flashlight if there were no fins. p is the fin pitch or distance between fins. So this area is of a small section of the flashlight that would contain one fin.
Then, a relevant quantity is (total surface area with fins)/(surface area without fins). This is just for the section of the light where there is finning, where it is most important.
So this quantity is (2*d*pi*D + p*pi*D)/(p*pi*D). Simplified, we get (2d+p)/p.
For example, with D=55mm, d=4mm, p=4mm, and 5 fins, approximately 6908mm^2 of area is added, and this increases the surface area of this section of the flashlight by a factor of 3.
ETA?
Mike
Exciting Times Ahead before it is done.
Endurance To Annoyance since I want it now 
All progress here in the thread.
Ah that reminds me. V5 driver is ready, too tired, will update OP with latest info on it tomorrow.
Something to think about while y’all are crunching fancy formula’s for heat sink fins…
How do we use a flashlight? Don’t we hold it horizontal in front of us? So the heat rising up from the fins on top is conducted away by air, what happens to the heat on the bottom side of the light? My point being that air flow doesn’t happen the same all the way around the light in a typical use scenario.
If more cooling is needed it would be far better to stay with the current fin design and simply stretch the head area 10-20mm to gain shelf mass and extra cooling fins. (Yes, make the light longer)
Funny you are.
Well, if you want to have 100500 lumens for 10sec., you are right. There will be great difference in temperature of parts and main profit will give dtp pcb.
But if you wait 20-30 minutes all parts of light will have same temperature with 5 deg.C from pcb to tail. Same tepmerature of whole host means same difference between host (heatsink) and surrounding area and same influence on heat transfert whenever you increase host area.
[quote=EasyB]
10*3.14*(55^2-51^2)/4=3330mm^2=33sq.cm., that allow you put extra 1.5W-2.0W for long time.
For example Ф50*135mm tube is 3.14*50*135=21200mm^2=212sq.cm.
Your fins are much more that 1-2%, but there is no place for 5 extra fins (5*4mm fins + 4*4mm place between them - where did you find 36mm of free place?)
All very good arguments, but frankly, without making huge changes to the overall design of the light, it’s not going to make much difference.
Including this: Unless you are in a cold climate, you won’t be able to leave this light on max for 20minutes without over heating. It’s simply too much power in too small of a package.
That’s what makes it fun!
To clarify, in my calculation the pitch, p, is the distance from the start of one fin to the start of the next fin, so it includes the fin and the space between the fins. So 5 fins would be roughly 20mm.
d is the radial depth, like if you put a ruler perpendicular to the flashlight surface. With d=4mm, if the OD is 55mm, the diameter at the bottom of the fins would be 47mm.
Wauw!
That Lux-RC (search image ) is art! That is a very cool design
Did I read something about adding a little bit of length?
A few of these extremely deep fins between led area and driver area would certainly help in cooling
But would it still be a soda can light?
Did I mention I am very tired? Haven’t slept more then 1 hour last night due to splitting headache so I could be getting carried away a bit too far here
Another part of the ‘fin equation’ is how machining/turning works. With square-cut fins the tool only cuts on it’s one end; easy to make/maintain/use/set up and is durable. Tapered fins use tooling cutting on two sides at once; more costly tool/harder to use and maintain/cannot cut as quickly/harder to set up properly/higher wear on tooling. Thus probably an increased cost, which we’re probably pushing the limits on now. Numerous thinner fins would work better too, but would be much more easily bent or damaged.
A good discussion and interesting, but I fear it isn’t going to happen here due to cost. And no reasonable amount of change to the finning will make this light run cool enough to walk away from in operation so at best you’ll only get a little more time before ramp-down needs to happen. In the end everything is going to boil down to cost, which many have noted they won’t accept any substantial increases of. But if the Q8 team wants to try for different finning I’m still in.
Phil
Have you ever seen passive heatsink with 2mm between fins? All such fins dont work at all (X6 and etc.).
Ok. It was really just an example to clarify the terms in my calculation.
I don’t remember if i signed up for one, but check to see and put me down for one.
When this light is done, can we also design a nice belt pouch for it?
I bought a military flash bang pouch to keep the Supfire M6 from Richard and that thing BARELY fits in there. I had to loosen the strap on the buckle all the way to where it only goes through one opening like this:
Eye keeping on you I am
Cheers David
DBSAR I am sure you are on the list already.
Yeah a major overhaul on the fins that adds costs and starts the process of getting the outside to look as we want again does not seem a good idea.
I hope people wanting a pouch and have a srk know of a fitting one !)