Strobe light on glider

I remember watching a documentary on WWII camouflage techniques and am reminded of one counter-intuitive technique that actually used bright lights in daylight to make equipment on the horizon visually disappear. I often ponder the true effectiveness of running with lights on in small powered planes during the day and whether there have been any studies to support the validity of this practice.

Now, you've got me wondering about the effectiveness of bright strobe strips during daylight flights.

Hmmm...

Paul A.
Treasure Coast Soaring Club
Vero Beach, FL

My Google Fu is strong today. I found a Wiki page about the use of counter-illumination for camouflage that was quite interesting to read.

en.m.wikipedia.org/wiki/Yehudi_lights

From what I'm reading, the brightness of the strobes could work against you as counter-illumination if they are not significantly brighter than the surrounding sky. On a bright, blue sky day, would a bright strobe strip help or hurt your visibility. As I said in my previous post...counter-intuitive....

Paul A.
Treasure Coast Soaring Club
Vero Beach, FL
@TCSoaring on Facebook

Don't have the energy (ha) today to do a detailed read, but something like this should give some clue:

http://www.imedpub.com/articles/avia...visibility.pdf

One sentence early on reads: "It is stated that an intensity of 350 cd is required for a signal light to be
visible from 0.125 miles away in conditions corresponding to a runway visual range of 0.125
miles".

So, 1/8 of a mile requires 350 Candela (in a runway setting, where there might be more contrast with ground items?) We probably want 1 mile ideally? So, some math converting Candela to Lumens (which is what is reported in the specs for strobes) would get you some rough approximation of the lumens required to be visible over some reasonable angle (steridians). A very quick back of the envelope tells me that a bike strobe (typically 200-400 lumens) is several orders of magnitude too weak to be useful. Maybe someone has the time to run numbers and make sure I didn't add when I should've divided etc.

P3

On Tuesday, January 24, 2017 at 3:23:12 PM UTC-5, Papa3 wrote:
Don't have the energy (ha) today to do a detailed read, but something like this should give some clue:

http://www.imedpub.com/articles/avia...visibility.pdf

One sentence early on reads: "It is stated that an intensity of 350 cd is required for a signal light to be
visible from 0.125 miles away in conditions corresponding to a runway visual range of 0.125
miles".

So, 1/8 of a mile requires 350 Candela (in a runway setting, where there might be more contrast with ground items?) We probably want 1 mile ideally? So, some math converting Candela to Lumens (which is what is reported in the specs for strobes) would get you some rough approximation of the lumens required to be visible over some reasonable angle (steridians). A very quick back of the envelope tells me that a bike strobe (typically 200-400 lumens) is several orders of magnitude too weak to be useful. Maybe someone has the time to run numbers and make sure I didn't add when I should've divided etc.

P3

There was another study that I posted a link to a couple of months ago. That study concluded that a reflective foil (mirror like) is hugely more effective than LED lights in bright light.

On another note, when ordering my new glider a year ago I asked German pilots about how good the LED lights on the gliders were. The response was not to bother with it.

Saying that LED strobe would sure help under a cloud street. In that situation even a bicycle strobe would help.

On Wednesday, January 25, 2017 at 12:00:01 PM UTC+13, Andrzej Kobus wrote:

Saying that LED strobe would sure help under a cloud street. In that situation even a bicycle strobe would help.

I'd be happy just to increase my chances in low light and high on collision risk situations like flying under cloud streets.

To say that, a conspicuity light MUST be effective in bright sunlight in order to be worthwhile, is missing the point.

On 25/01/2017 01:00, Andrzej Kobus wrote:

There was another study that I posted a link to a couple of months
ago. That study concluded that a reflective foil (mirror like) is
hugely more effective than LED lights in bright light.

The UK Military gliding group did a study into high visibility markings
years ago. They did a bunch of flight tests with motor gliders. I think
they found that most markings were not very effective, but reflective
mirror strips on the control surfaces were the most useful. As the
controls move about there is more chance of a reflection flash catching
the other pilots attention.

It was written up in Sailplane and Gliding. It would probably be worth
finding that article before you spend money on anything.

At 06:49 25 January 2017, Ian wrote:
On 25/01/2017 01:00, Andrzej Kobus wrote:

There was another study that I posted a link to a couple of months
ago. That study concluded that a reflective foil (mirror like) is
hugely more effective than LED lights in bright light.

The UK Military gliding group did a study into high visibility markings
years ago. They did a bunch of flight tests with motor gliders. I think
they found that most markings were not very effective, but reflective
mirror strips on the control surfaces were the most useful. As the
controls move about there is more chance of a reflection flash catching
the other pilots attention.

It was written up in Sailplane and Gliding. It would probably be worth
finding that article before you spend money on anything.


Problem is that adding foil to the control surfaces would probably alter
the weight and balance beyond limits

I know the reflective foil/tape is very light, but consider the possible
impact (a pun, perhaps?) of causing an imbalance on a control surface.

On 1/24/2017 11:49 PM, Ian wrote:
On 25/01/2017 01:00, Andrzej Kobus wrote:

There was another study that I posted a link to a couple of months
ago. That study concluded that a reflective foil (mirror like) is
hugely more effective than LED lights in bright light.

The UK Military gliding group did a study into high visibility markings
years ago. They did a bunch of flight tests with motor gliders. I think
they found that most markings were not very effective, but reflective
mirror strips on the control surfaces were the most useful. As the
controls move about there is more chance of a reflection flash
catching the other pilots attention.

It was written up in Sailplane and Gliding. It would probably be worth
finding that article before you spend money on anything.


--
Dan, 5J

Am Mittwoch, 25. Januar 2017 07:49:35 UTC+1 schrieb Ian:
On 25/01/2017 01:00, Andrzej Kobus wrote:

There was another study that I posted a link to a couple of months
ago. That study concluded that a reflective foil (mirror like) is
hugely more effective than LED lights in bright light.

The UK Military gliding group did a study into high visibility markings
years ago. They did a bunch of flight tests with motor gliders. I think
they found that most markings were not very effective, but reflective
mirror strips on the control surfaces were the most useful. As the
controls move about there is more chance of a reflection flash catching
the other pilots attention.

It was written up in Sailplane and Gliding. It would probably be worth
finding that article before you spend money on anything.

I still think that they did not ask the right question. They asked: What is the average distance at which skilled pilots detect the other traffic, and the distance varied a little bit with the methods, but was always well above the distance necessary to avoid the other traffic. They should have asked the question: How high is the likelihood that the other traffic is detected at a distance of 2 NM. And how you value the different methods might be very different when you use the second question and not the first.

Am Mittwoch, 25. Januar 2017 07:49:35 UTC+1 schrieb Ian:
On 25/01/2017 01:00, Andrzej Kobus wrote:

There was another study that I posted a link to a couple of months
ago. That study concluded that a reflective foil (mirror like) is
hugely more effective than LED lights in bright light.

The UK Military gliding group did a study into high visibility markings
years ago. They did a bunch of flight tests with motor gliders. I think
they found that most markings were not very effective, but reflective
mirror strips on the control surfaces were the most useful. As the
controls move about there is more chance of a reflection flash catching
the other pilots attention.

It was written up in Sailplane and Gliding. It would probably be worth
finding that article before you spend money on anything.

I still think that they did not ask the right question. They asked: What is the average distance at which skilled pilots detect the other traffic, and the distance varied a little bit with the methods, but was always well above the distance necessary to avoid the other traffic. They should have asked the question: How high is the likelihood that the other traffic is detected at a distance of 2 NM. And how you value the different methods might be very different when you use the second question and not the first.