Strobe flash rates

[Genghis the Engineer]

FAR-25 (and a few other derivative standards) require that aircraft strobes flash at a rate of between 40 and 100 per minute.

Does anybody know where that figure came from, and whether there are any particularly good reasons (apart from not getting them certified) not to have faster or (more likely) slower strobe cycle rates?

G

[Notso Fantastic]

There's a particular strobe flashing rate to be avoided that makes people go funny in discos. This higher flashing rate would be unpleasant to be near, a slower rate wouldn't do the job. There seems to be a double flash that is effective. I suppose a lot of it depends on the capacitance available in the electronic circuits- keeping it relatively simple without drawing too much energy.

[NSEU]

I suppose if you wanted them to flash at a much faster rate at the same intensity, you would need a much larger power supply (with bigger/less fragile transformers, capacitors, etc). The power supplies on your average jet aircraft are already quite large/heavy compared to the size of the lamp. The power supplies are often remotely located, so the interconnecting wiring may have to be beefed up.

Rgds.
NSEU.

[av8boy]

I looked at this question a while back, and I don't remember the specifics now... If memory serves, the flash rate was arrived-upon after discussion in 1953 or 1954. Sorry I don't have more to offer at this point, but I believe that the rate is the same now (in the regs) as it was then...

Dave

[Flight Safety]

I think the flash rate has something to do with the human eye and brain's ability to quickly pick up the flashing strob. I seem to remember reading something about a 44Hz rate being the most recognizable rate at night, and 88Hz during the day. I've also read somewhere that some strob systems have a selectable day or night rate, but I've never seen this myself.

[BusBoy]

Double flash = Airbus
Single flash = Boeing