Federal Signal Federal Signal Strobehawk history

Yep, Federal Signal made great beacons and lightbars with rotating sealed beam bulbs or rotating reflectors, but their strobes were weak when compared to the leader of the strobe pack, Whelen.
Great video, about a really unique bar. I wish I'd kept mine.

The tech behind the Federal Strobes in the StrobeHawk was interesting....

What @RS485 figured out was that Federal thought that making the two double flashes the same brightness vs. one bright with a less bright follow up (like Whelen strobe II) would make a huge difference. This was based off of their interpretation of several studies, one being pretty old and one being a coast guard study on open water.

The speed of a flash does lead to increased recognition speed and the brightness at that speed does matter. However, it wasn't clear that their logic claiming that two equal flashes within the same time period (.25 sec) is better than one bright one with a slightly less bright follow up was based on the papers they referenced. Also the definitions of perceived brightness and recognition weren't necessarily the same thing. My own unscientific observations found that while looking right at the tube the two equal flashes appeared brighter, but when not focusing on it there was no change in "getting my attention" between the equal brightness and the flash with lower intensity second flash.

The other issue is overall power. If the starting brightness/power is proportionately brighter, the follow up flash being lower power matters less. A 15J primary with a 9J secondary could still be superior to two 12J equal flashes. It is also unclear where the drop off is in time, number of total flashes, power difference between flashes, peak brightness, and dwell time of all flashes. Even if you get all of that right that doesn't consider basics like reflector design. If you put the best designed strobe system in the world under a 360 dome inside another dome and don't add a sun shade your power supply isn't going to matter as much.

The other factor making the design less practical was that in order to get the two equal flashes there was some extra capacitor work/design to be done that probably didn't justify the very marginal (if any) improvement.

Sorry to hijack, the strobe "science" rabbit hole goes deep.

Forum Statistics

Latest member