On Tuesday, September 18, 2018 at 8:08:49 PM UTC-7, Gerry Simpson wrote:
Does anyone have knowledge of documented studies showing the efficacy of the strobe light bars which are available to be installed in the leading edges of the vertical stabilizers on gliders? Is there anything beyond anecdotal experience to support their use to improve visibility to other aircraft beyond a minuscule amount? Has anyone had experience that they are willing to share? To what extent does an installation disrupt the laminar airflow around the vertical stabilizer?

While not answering your question, I did do a test on my LED landing/taxi wig-wag install on my Husky. These are super bright lights and the alternating flashing is attention getting as well. At 36 watts each and four lamps - absolutely no comparison to what Schleicher installs in the leading edge. here's the test results:

Jim J. flew over to Minden, NV this morning, and I launched to meet him head-on (well, almost so) near South Lake Tahoe (KTVL) at 9,800'. It was close to 10 AM, with the sun low off my left wing in the high overcast, winter sky. The object was to see how or if pulsed AeroLEDs would enhance the "see" part of see and avoid, and in particular, if threat aircraft acquisition distance would be increased.

Before discussing our non-scientific findings, a couple of notes. My aging vision is corrected to 20-13, been better than average all my life. I usually have "joy" on other small aircraft at a minimum of 3 miles when I don't have my head where it doesn’t belong. I've read that flashing lights are advantageous as they are more easily picked up in one's peripheral vision. LED's, with their almost instant rise and fall time, or on and off, give an effect akin to a strobe light. So in flash mode are more attention getting than incandescent lamps. A wig-wag, back and forth flash sequence is said to impart a sense of motion sort of visual response to help us pick up a target faster.

Distance results were somewhat disappointing, at least for our several test runs. We'd pass each other head on, fly for about a minute, then turn and re-acquire from a starting distance of 4 miles or so. In each case, we both agreed that when we would be able to pick up the other's aircraft, the lights were visible at or nearly at the same time as the aircraft itself. I don't think that, at least in daylight and at 3 miles or so distance, the lights are particularly effective at extending the acquisition distance beyond what one would detect without the lights on. I'm thinking that this is probably due to the small relative size of the target at that range - - the lights are tiny pin pricks of light winking on each wing tip. BUT, I'm very sure a regular incandescent or halogen lamp, under the same conditions, would not be discernable at all until the aircraft got much closer.

Now, closer in is another story. If one missed picking up on an incoming aircraft until it was closer, say at a mile or so, and in most of the frontal arc, then I do think the AeroLEDs may provide a significant safety enhancement to collision avoidance. I have no good way to confirm or test this, save from briefly looking away and then allowing my peripheral vision to pick up Jim's aircraft's movement when he was closer, the lights seem to what attract the old eyeballs first.

I've heard, and my own experience confirms, that lights help avoid bird strikes. Flying from the N. Bay area down to Half Moon Bay, CA, flying the coast, one is almost forced to fly low under S.F.'s Class B airspace. I've watched a number of birds do the "Oh s%&t I'm gonna die!" diving, collision avoidance maneuver in response to the flashing lights on my Mooney. Never did nail one.

bumper