After having come across by accident some information about COB LED's it seems that a COB (chip on board) LED would make a good flashlight for some kind of purpose since it can be obtained in a rather small diameter and it can put out about 100-130lm/w. There are other multiple advantages as well. This page has a comparison of a Ceramic COB LED vs an Aluminum COB LED vs a typical high power single LED.
Just to quote something from the page above "COB LEDs have great advantage of thermal resistance, larger cooling area, better lighting effect and high light efficacy."
Since I am an BLF Illumination Engineer-in-training (and at the very start of my training yet!) can one or more of our "Elite BLF Scientists" or anyone else chime in as to if the idea of a COB LED Flashlight would be plausible and practical? Come on - do not be shy.
The main website for the COB LED's from the above links have much more information.
Thank you for your input.
If you have any questions on what is cob light used for. We will give the professional answers to your questions.