Wingtip to Runway light protector Concepts

On Tuesday, January 3, 2017 at 11:23:33 AM UTC-5, Dan Marotta wrote:
If the glider's wing contacts a runway light or deflector at "landing
speed" you should direct your budget at pilot training.

I think the concern is that last few knots with a cross wind and no more
rudder or aileron authority. But then the brake should be sufficient by
that time.
--
Dan, 5J

Well nice theory that better training is the whole answer, primary training is where we have seen the damage - the longer wings flown by students. The last few feet with limited contrl and the wind are a factor. So an impact ever few hundred cycles is not hard to imagine.

Your proposed deflector would have to be pretty narrow not to block the
light from view. Something narrower than the runway light would cause
more damage to a wing than the light itself. Think pounds per square
inch or a woman's high heel shoe. Removable runway lights would be a
much better solution.

On 1/3/2017 11:21 AM, wrote:
On Tuesday, January 3, 2017 at 11:23:33 AM UTC-5, Dan Marotta wrote:
If the glider's wing contacts a runway light or deflector at "landing
speed" you should direct your budget at pilot training.

I think the concern is that last few knots with a cross wind and no more
rudder or aileron authority. But then the brake should be sufficient by
that time.
--
Dan, 5J
Well nice theory that better training is the whole answer, primary training is where we have seen the damage - the longer wings flown by students. The last few feet with limited contrl and the wind are a factor. So an impact ever few hundred cycles is not hard to imagine.

--
Dan, 5J

On Tuesday, January 3, 2017 at 1:54:01 AM UTC-5, Heinz Gehlhaar wrote:
Did you calculate the loads on the glider-wing/deflector as the glider strikes the angle of the deflector at landing speeds and considering the roll inertia of the glider? My gut-feel tells me that the angle needs to be much shallower.

No calculations yet. I wanted to throw the concept out for public comment before I sank any time into development. I figured someone else already could tell me of a current solution or a good reason to abandon the whole idea - such as saying the FAA would never allow such a thing.

You would need to figure out the forces and I was thinking this would be for when the glider was in it's last 1/3 of the ground roll, from ~20 to 0 knots perhaps. I agree with your suggestion that the angle would need to be shallower.

It is worth considering what would be worse to have the wing hit the light, or wing deflected up and other wing slammed down.

Also with either idea I think there would still be some scratching or denting damage to the glider's leading edge. The idea is to prevent the whole leading wing from being crushed in as far as the spar and leaving it unairworthy.

Most runway lights I know of are designed to break off at the base when struck. Putting a reinforced structure over them seems problematic, particularly if you strike them from the side with, say, the fuselage or a power plane hooks the loop with a wheel. You also might want to see if the FAA has any requirements about what sorts of obstructions are permitted near a runway..

I like the system Rex Mayes installed at Montague, CA. Each light was put on a simple pivot slightly below ground level and encased with an irrigation box with a notch cut in the center of the long edge of the cover for the light post to fit through such that the closed cover holds the light in the up position. It covers the retracted light completely and is flush with the ground when the light is retracted.

You put the lights down at the beginning of operations and put them back up at the end of the flying day - before dusk of course. Changing configurations takes about as long as it takes two people to walk the length of runway you want clear. Generally this is only a few hundred feet if you are concerned about wing drops on takeoff, but may include the primary rollout area as well.

Here's an example of the irrigation box:

http://tinyurl.com/hkxoqa6

Hope that helps.

Andy Blackburn
9B

On Monday, January 2, 2017 at 5:53:09 AM UTC-8, wrote:
My club recently had its first wingtip damage from a runway light. These lights stick up about a foot or so and are sometimes hard to avoid.

What solutions have other soaring clubs found to deal with them?

I was thinking that it maybe a good idea to put a deflector in front of the lights. If the wing is going to hit, it would hopefully deflect the wing up and over the light.
I was hoping the right design might not obscure the light any more than a tall weed. What are chances of getting something like this approved or accepted by either an airport authority or the FAA?

My first two concepts we
1. form a steel rod that goes over the light, and then front and back ends form spikes that could be hammered into the ground.
2. A wedge shaped cut plexiglass/acrylic sheet that the light could pass through. The bottom would have flanges heat formed to a allow it to be secured to the ground.

Please post any feedback or thoughts on if there is some solution to help protect glider wings.

I made simple sketches here, Please forgive the really crude drawings:

https://docs.google.com/presentation...it?usp=sharing

a href="https://docs.google.com/presentation/d/1DhfbsEk49m-3LS-Vzs8YO-487Gv1YDjZNICBma72tlE/edit?usp=sharing"concept drawings/a

Chris

Correction, I mistyped - the notch is in the center of the edge of the box along the long axis - this gives you about 18 inches of light height you can accommodate.

9B

On Monday, January 2, 2017 at 11:34:59 PM UTC-8, Andy Blackburn wrote:
Most runway lights I know of are designed to break off at the base when struck. Putting a reinforced structure over them seems problematic, particularly if you strike them from the side with, say, the fuselage or a power plane hooks the loop with a wheel. You also might want to see if the FAA has any requirements about what sorts of obstructions are permitted near a runway.

I like the system Rex Mayes installed at Montague, CA. Each light was put on a simple pivot slightly below ground level and encased with an irrigation box with a notch cut in the center of the long edge of the cover for the light post to fit through such that the closed cover holds the light in the up position. It covers the retracted light completely and is flush with the ground when the light is retracted.

You put the lights down at the beginning of operations and put them back up at the end of the flying day - before dusk of course. Changing configurations takes about as long as it takes two people to walk the length of runway you want clear. Generally this is only a few hundred feet if you are concerned about wing drops on takeoff, but may include the primary rollout area as well.

Here's an example of the irrigation box:

http://tinyurl.com/hkxoqa6

Hope that helps.

Andy Blackburn
9B

On Monday, January 2, 2017 at 5:53:09 AM UTC-8, wrote:
My club recently had its first wingtip damage from a runway light. These lights stick up about a foot or so and are sometimes hard to avoid.

What solutions have other soaring clubs found to deal with them?

I was thinking that it maybe a good idea to put a deflector in front of the lights. If the wing is going to hit, it would hopefully deflect the wing up and over the light.
I was hoping the right design might not obscure the light any more than a tall weed. What are chances of getting something like this approved or accepted by either an airport authority or the FAA?

My first two concepts we
1. form a steel rod that goes over the light, and then front and back ends form spikes that could be hammered into the ground.
2. A wedge shaped cut plexiglass/acrylic sheet that the light could pass through. The bottom would have flanges heat formed to a allow it to be secured to the ground.

Please post any feedback or thoughts on if there is some solution to help protect glider wings.

I made simple sketches here, Please forgive the really crude drawings:

https://docs.google.com/presentation...it?usp=sharing

a href="https://docs.google.com/presentation/d/1DhfbsEk49m-3LS-Vzs8YO-487Gv1YDjZNICBma72tlE/edit?usp=sharing"concept drawings/a

Chris

They do make flush runway lights, last time I looked it was about $500 per light though. As lights get broken work with airport management to get them replaced with flush mounted lights. Granted a slow developing solution, but should be part of the solution plan along with others mentioned above.

Flush light won't work so well we're it snows.

I used to joke that one reason I landed out so much was because airport's were so dangerous. Airplanes, runway lights, and other hazards are everywhere at municipal airports that just don't exist in a nice farmer's field.

I was kidding...sorta

Snow? Forgot about that stuff. That is the white stuff, I see it from the air when flying over the mountains. I did grow up in Idaho, skiing, climbing..etc. But I guess the last 30 years living in San Diego, I forgot about the effects of weather below 65 degrees.

On Tuesday, January 3, 2017 at 7:12:35 AM UTC-8, Tony wrote:
Flush light won't work so well we're it snows.

I used to joke that one reason I landed out so much was because airport's were so dangerous. Airplanes, runway lights, and other hazards are everywhere at municipal airports that just don't exist in a nice farmer's field.

I was kidding...sorta

On 1/3/2017 8:12 AM, Tony wrote:

I used to joke that one reason I landed out so much was because airports
were so dangerous. Airplanes, runway lights, and other hazards are
everywhere at municipal airports that just don't exist in a nice farmer's
field.

I was kidding...sorta


Heh...historically, runways - like roads - exert a powerful pull on lower-time
glider pilots when it comes to "choosing an ideal XC landing field." When I
edited my club's monthly newsletter for a number of years, a continual safety
drumbeat was words to the effect: the only certain thing about an active
(paved) runway (designed for powerplanes) is a (presumably) known (relatively)
decent surface. Particularly in the high plains and intermountain west, it's
easy to find narrow paved strips with nearby lurking light standards, each and
every one salivating at the thought of glider wingtips. "Runway complacence"
definitely not recommended!

Bob W.

On Tuesday, January 3, 2017 at 2:34:59 AM UTC-5, Andy Blackburn wrote:
Most runway lights I know of are designed to break off at the base when struck.

Yes these are designed to break off at the base, but apparently not until they have done major damage to a glider wing. The yield strength must be pretty high.

I stumbled across this in AC 150/5345-46D - not sure it is for this type fixture but if true then our lights are ~1 foot tall, so maybe they are required to withstand 150lbs. They might not yield until 500lbs! That is a lot of force for a point of contact.

3.4.2.1. Yield Device.
a. Each elevated light fixture must have a yield point near the point or position where the light attaches to the base plate or mounting stake. The yield point must be no more than 1-1/2 inches (38.10 mm) above grade, must give way before any other part of the fixture is damaged, and must withstand a bending moment of 150 foot-pounds (203 Newton-meters (N-m) without failure.

(1) This yield point must also separate cleanly from the mounting system before the bending moment reaches 500 foot-pounds (678 N-m).