Wingtip to Runway light protector Concepts

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

Our club has taken out a few lights (vertical lights on short post) with the trainer 2-33, I always thought a longer wing wheel rod/bracket would have kept the wing above the lights, but not a solution for high performance.

Generally it is much easier to keep the fuselage from hitting light than the wings, so setting the wing tip above the lights would work.

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.

On 1/2/2017 11:53 PM, Heinz Gehlhaar wrote:
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?
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.

--
Dan, 5J

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.

On 1/2/2017 11:53 PM, Heinz Gehlhaar wrote:
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?
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.

--
Dan, 5J

From a guy with a self leveling glider. We teach about this issue constantly, mostly because we fly in a very space restricted facility with respect to width.
I suspect others have the same issue.
UH

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.

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).

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.

Ask Bruno or Ron about marker lights. They had many examples of amputated lights at Nephi. No students involved.
Hadn't heard of Rex's mod at Montague, sensible.
Jim

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.

Years ago I operated a Nimbus 3 off of the little airport at Montague. The runway lights had claimed at least two glider wing kills that I knew of and my long wings were at high risk. I purchased some 6 inch diameter PVC pipe and split some 8 foot sections in half with a table saw. I would shove the near side end into the gravel and lay the far side end on top of the light. It worked for me on the one occasion I needed it and only left a slight scuff on the bottom of the wing. I covered four lights on each side in the probable impact zone and had my wing runner remove them after launch. Cheap and easy. I know others borrowed them and I think they helped. Rex Mayes came along later and did it the right way, but not many small airport FBO's are also the glider operation.
Dale