[PART 1] Official BLF GT Group Buy thread. Group buy officially closed! Lights shipping.

Fritz, if anything, the fins seem to act as a dyk/buffer to keep tube cool, I like that, i hate hot cells :wink:

Agree with J-Dub74 one a “tactical” ring, italso is nice anti roll

Vol,it is clear you want another light to be made, thatis cool,but this is not the toic for that.
As erommel did withtherecoil thrower I suggest you start a topic for it, BLFs a very friendly and helpfull community so who knows what is going to happen there then.

It is indeed good to see a large reflector for ~$3,20
sureit is not the size we want but still it is huge for the price of a C8 reflector, nice.

And of to update the OP!

Yes OP list updated, all should be there.

Jerommel, this stage is getting an idea and for us away to show the idea
We all understand that the disign to be chosen will need some tweaking along the way or details adaptations.

Here my design for the BLF GT. Some details are mentioned further down :slight_smile:



  • Attachment points for shoulder strap
  • Tripod mount close to the centre of mass
  • Illuminated switch
  • Tailswitch
  • Anti roll design
  • Fine thermal behaviour
  • (Possibly) Plastic cups on tailcap and bezel to minimise impact when dropped and increase durability.

Please note the designs are just conceptual and no matter which design will be chosen there will probably be some small changes (Mine for example might get some more anti-rolling details).

Here is a thermal analysis which uses quite strict values:

The reality will be colder. For more information about heat and the fin placement see here and here.

Additionally, IF some folks are interested in a handle and would be willing to pay a little extra for this feature, this design allows an easy attachment of a handle. This would not add any costs for anyone who doesn’t want a handle! However, this is just theory and would depend on the amount of people who would want a handle.

And finally I have to say how awesome the BLF community is. We are creating this unique light, so many people have valuable input and we have several different amazing designs of which we can choose from. :+1:

I bet Thrunite is watching, maybe Acebeam too! Since they started the XHP35 thrower revolution! It’s only common sense that a bigger thrower would come out, eventually! :wink: Maybe not for a “Budget” price,which is yet to be seen so far, but you never know!

So get cracking!!! :smiley: :+1:

Yeah Kawi!

Fritz amazing post! Thanks.

I have to say it is going to be a very hard choice between these great designs… When does the voting start?

Fritz,that`s it :+1:

Regards Xandre

Tonight at 23 local time (~9 hours from now) I am going to build the poll
Including two pics (or one with the design twice) of each design and a link to the post of designer where they can have more pics and a talk aboit it (so for Fritz the blpost above for example)
Of course an nonsense option and the possibility to choose “I am OK. With whatever design, just make the GT”

Very nice look'n design! I like the overall shape, just not a fan of all the smooth surfaces. Not sure bout the whole thermal analysis - the fins as designed do not gain all that much surface area - too few, too thick, too shallow, and from their location and size, I'd say they will do very little, not even worth having. Are the threaded connections taken into account, and if so, how does/would a good thermal conductive treatment on those threads effect it? I've seen actual thermal imagery of the effect and it's significant. Also for thermal imagery, all depends on time lapse - hot zones tend to spread over time. What you are showing there is a simple snap shot at one moment. You reach a critical max temp, then it spreads over time. In reality, it's pretty complicated, and with other factors you mentioned - holding it, ambient temperature/humidity, etc.

Hi, you are of course right, this is just a theoretical consideration. However, the conditions are worse in the analysis than they are in real life and it is just meant to see that it works. The heat distribution with the boundary that heat is added as well as the ambient temperature will converge to some equilibrium for a large Time t. Those thermal analysis consider the equilibrium state.

This has been one heck of a thread. Hard to follow as it seems to move at the speed of light :wink: but fascinating from the start.
Fritz, while I don’t necessarily want this light to be the BLF GT that is only because I was already completely sold on the 5AR design. Your unexpected entry here took me by surprise. I would definitely love to see your light in production not necessarily as the GT but how about the GTX? :student: I’m at the point where I refuse to choose. The unique look of your light with the handle is just awesome. I want them both. Well done. :+1:

I like the surface treatments of the HaikeLite MT07 for example, don't care for the smoothness of the TN42 design, though the overall shape/form factor of the MT07 is awful and the TN42 is better. The MT07 and TN42 are almost two opposite extremes of designs for big lights - TN42 is designed for light weight and a thin look, MT07 doesn't care how heavy or butt ugly it is...

Hi, thanks! Maybe if it won’t be the BLF GT design something with a 90mm reflector and an XHP70 would be interesting as well :smiley:

I’m IN! :+1:

Fritzs, I am really curious, what happens if you do the thermal analysis with ~240W+ of power from the LED as would be the case in a quad XHP70? Or even 120W from quad XHP35? Or what about ~80W from a single XHP70?

The idea with this light is to be overbuilt to the extreme to allow for anything we could possible dream up later to be easily done.

This is relevant, I am sure this will be a popular mod for some that need to maximize lumens, given the battery choice.

I can do that. To be honest, I am kind of hoping for a single die XHP70 which I could put in this light haha. But I actually feel like just taking the wattage of the LED is a little bit overkill. Do you know how much of the overall power gets actually converted into heat? Because surely not all of the 10 W of an XM-L2 are just heat right? Or am I wrong here?

I also have to say I feel quite insecure about the convection coefficient, as I don’t have any experience there. I also don’t find any real world values. Here they have a table with velocity and convection coefficient:

So according to this plot from the same page

I’d say a value around 27 sounds about right.

The majority of the wattage turns to heat, the only way energy is removed without heat in the light is the little that the light photons carry away.

I think it is around ~20% at the levels we drive LED’s at the most.

For ease of math I would just use the full number because someone will drive them harder and make up the difference lol.

The quad setup I know will be thermally limited even in a light this large but the longest possible runtime before a thermal stepdown would be ideal.

I think it is the opposite of luminous efficiency. A quick search suggests that about 75% of the input energy as heat would be a reasonable value.

Edit: Texas_Ace beat me to it. But it’s good that we came up with about the same numbers.

Tactical ring on the battery tube has a function as a place for a shoulder strap to attach, and of course that is removable.

cigar-carrying it LOL

fritz15 you're right, here compared to your new design.

fritz15 Congratulations on your design, I know it is not easy to make such a harmonious design. Well done.

and other designers want to thank you for a well done job.