Wingtip to Runway light protector Concepts [Archive]

January 2nd 17, 01:53 PM

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 were:
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/d/1DhfbsEk49m-3LS-Vzs8YO-487Gv1YDjZNICBma72tlE/edit?usp=sharing

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

Chris

[email protected]

January 2nd 17, 03:19 PM

On Monday, January 2, 2017 at 8:53:09 AM UTC-5, 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 were:
> 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/d/1DhfbsEk49m-3LS-Vzs8YO-487Gv1YDjZNICBma72tlE/edit?usp=sharing
>
> <a href="https://docs.google.com/presentation/d/1DhfbsEk49m-3LS-Vzs8YO-487Gv1YDjZNICBma72tlE/edit?usp=sharing">concept drawings</a>
>
> Chris

Our club has removable barriers over end marking lights at one end of our field so we don't rip them out with tow ropes. Not a landing area but short of it for tugs.
We put low light plastic cones over the lights near our operating area to make them much more visible. This is effective in preventing almost all hits. They also seem to moderate damage when hit happens which is now very rare.
We put all this stuff(3 barriers and about 12 cones) up each day. Takes 5 minutes on the golf cart.
Experience shows that if lights can be seen they get avoided pretty much all the time.
We operate in grass parallel to the paved runway having lights.
UH

chuck[_3_]

January 2nd 17, 10:35 PM

Which ship took the hit?

Charlie M. (UH & 002 owner/pilot)

January 2nd 17, 11:00 PM

Yes........ I believe more than one over the years.

[email protected]

January 3rd 17, 01:04 AM

On Monday, January 2, 2017 at 5:35:03 PM UTC-5, chuck wrote:
> Which ship took the hit?

K-7 this time, could be any next time.

Heinz Gehlhaar

January 3rd 17, 06:53 AM

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.

Andy Blackburn[_3_]

January 3rd 17, 07:34 AM

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

Andy Blackburn[_3_]

January 3rd 17, 07:38 AM

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

Jonathan St. Cloud

January 3rd 17, 07:54 AM

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.

Tony[_5_]

January 3rd 17, 03:12 PM

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

Jonathan St. Cloud

January 3rd 17, 03:26 PM

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

Scott Williams

January 3rd 17, 03:30 PM

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.

Dan Marotta

January 3rd 17, 04:23 PM

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

[email protected]

January 3rd 17, 05:04 PM

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

[email protected]

January 3rd 17, 05:53 PM

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.

[email protected]

January 3rd 17, 06:15 PM

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).

[email protected]

January 3rd 17, 06:21 PM

January 3rd 17, 06:34 PM

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

BobW

January 3rd 17, 06:43 PM

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.

[email protected]

January 3rd 17, 07:34 PM

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

George Haeh

January 3rd 17, 11:09 PM

The maximum spacing between runway edge lights is 200'. Airport operators

are unlikely to spend the extra money for tighter spacing.

200' hopefully is enough space to stop the glider from a speed where you
still
have aerodynamic control.

On your first glider landing on pavement you will discover a longer ground

roll, especially if there's a downhill gradient.

I was thinking I could steer the glider off between the lights but ran out
of
energy as the slow speed passing the last light was not enough to get off
the
side.

But there's other nasty stuff that can lurk alongside paved runways.

Those with better skills can turn off onto a taxiway - watch out for props.

Better to stop on the runway and assess where you can safely pull off the
glider.

It helps to know the local airports and which ones are not suitable.

Dan Marotta

January 4th 17, 04:11 PM

My objection was with the "landing speed" case.

I've only flown a "self leveling" glider for about 9 months and,
frankly, I'm more concerned about tip strikes now with the long wings
which can rock down to runway sign height with very little wind. I was
never concerned about catching a wingtip in a single wheel glider. With
no more than a few knots IAS, it just takes paying attention to keep the
wings pretty much level. Slower than that, use the brake. If your
brake doesn't work, fix it.

There's just too much talk these days about protecting us from the
perils of the pursuits we choose to take and not enough attention to
developing the skills necessary to enjoy them safely and handle the
occasional curve ball.

On 1/3/2017 10:04 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.
>>
>> 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

--
Dan, 5J

Steve Koerner

January 4th 17, 04:27 PM

I've got a better idea to solve the runway light problem... Let's put a push-button switch on the left and the right side of the control column. If holding the stick hard over is not seeming sufficient to raise a wing over a runway light, then push the button on the down wing side of the stick for additional lifting force.

The push-button controls a solenoid valve that releases a jet of compressed gas through a nozzle on the underside of the wing that needs lifting. Most of us out west already carry a bottle of compressed gas that is used for another purpose. All that would be needed is plumbing in the wings as well as a nozzle outboard on each wing. The nozzle could be taped over to avoid adding drag. Such cold gas thrusters have been used for space vehicle attitude and other purposes; there is a body of design information on the subject.

Besides solving the runway light problem, a wing thruster could be used to address various other matters of urgency related to low speed roll control during takeoff and landing and might also be used to facilitate safe take off without a wing runner.

(you heard it first on RAS)

[email protected]

January 4th 17, 04:48 PM

On Wednesday, January 4, 2017 at 11:27:26 AM UTC-5, Steve Koerner wrote:
> I've got a better idea to solve the runway light problem... Let's put a push-button switch on the left and the right side of the control column. If holding the stick hard over is not seeming sufficient to raise a wing over a runway light, then push the button on the down wing side of the stick for additional lifting force.
>
> The push-button controls a solenoid valve that releases a jet of compressed gas through a nozzle on the underside of the wing that needs lifting. Most of us out west already carry a bottle of compressed gas that is used for another purpose. All that would be needed is plumbing in the wings as well as a nozzle outboard on each wing. The nozzle could be taped over to avoid adding drag. Such cold gas thrusters have been used for space vehicle attitude and other purposes; there is a body of design information on the subject.
>
> Besides solving the runway light problem, a wing thruster could be used to address various other matters of urgency related to low speed roll control during takeoff and landing and might also be used to facilitate safe take off without a wing runner.
>
> (you heard it first on RAS)

I think your idea blows! LOL
Full development of the idea would automate so that it is actuated when the stick is at a specified position, say 90% of available motion, and speed below a specified level, say 40 mph or so.
UH

January 4th 17, 06:31 PM

On Wednesday, January 4, 2017 at 8:27:26 AM UTC-8, Steve Koerner wrote:
> I've got a better idea to solve the runway light problem... Let's put a push-button switch on the left and the right side of the control column. If holding the stick hard over is not seeming sufficient to raise a wing over a runway light, then push the button on the down wing side of the stick for additional lifting force.
>
> The push-button controls a solenoid valve that releases a jet of compressed gas through a nozzle on the underside of the wing that needs lifting. Most of us out west already carry a bottle of compressed gas that is used for another purpose. All that would be needed is plumbing in the wings as well as a nozzle outboard on each wing. The nozzle could be taped over to avoid adding drag. Such cold gas thrusters have been used for space vehicle attitude and other purposes; there is a body of design information on the subject.
>
> Besides solving the runway light problem, a wing thruster could be used to address various other matters of urgency related to low speed roll control during takeoff and landing and might also be used to facilitate safe take off without a wing runner.
>
> (you heard it first on RAS)

Haha!
Perhaps Steve got the calendar mixed up 1/4 versus 4/1.
Jim

Andy Blackburn[_3_]

January 4th 17, 09:48 PM

On Wednesday, January 4, 2017 at 8:27:26 AM UTC-8, Steve Koerner wrote:
> I've got a better idea to solve the runway light problem... Let's put a push-button switch on the left and the right side of the control column. If holding the stick hard over is not seeming sufficient to raise a wing over a runway light, then push the button on the down wing side of the stick for additional lifting force.
>
> The push-button controls a solenoid valve that releases a jet of compressed gas through a nozzle on the underside of the wing that needs lifting. Most of us out west already carry a bottle of compressed gas that is used for another purpose. All that would be needed is plumbing in the wings as well as a nozzle outboard on each wing. The nozzle could be taped over to avoid adding drag. Such cold gas thrusters have been used for space vehicle attitude and other purposes; there is a body of design information on the subject.
>
> Besides solving the runway light problem, a wing thruster could be used to address various other matters of urgency related to low speed roll control during takeoff and landing and might also be used to facilitate safe take off without a wing runner.
>
> (you heard it first on RAS)

NASA calls that RCS (Reaction Control System). Might be useful during flight in the atmosphere too. I'm thinking about all those times when I realized I'd rolled into the thermal in the wrong direction...

;-)

9B

Dan Marotta

January 5th 17, 01:28 AM

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

January 5th 17, 06:47 PM

OK, I'll Bite, WTF is a self leveling glider?

After our Grob's encounter with a runway light, we no longer condone attempting to roll off the runway in a club ship. Stop it on the runway, get out, and push it off. Not a 100% guarantee, but the collision speed will be much lower.

SF

[email protected]

January 5th 17, 07:45 PM

On Thursday, January 5, 2017 at 1:47:02 PM UTC-5, SF wrote:
> OK, I'll Bite, WTF is a self leveling glider?
>
> After our Grob's encounter with a runway light, we no longer condone attempting to roll off the runway in a club ship. Stop it on the runway, get out, and push it off. Not a 100% guarantee, but the collision speed will be much lower.
>
> SF

Stemme has a 2 wheel(though narrow) landing gear.
Humor goes no where.
UH

Ventus_a

January 5th 17, 09:52 PM

Scott Williams

January 6th 17, 01:55 AM

Stemme gliders run in the $250,000 range, color me jealous.

Good Lift,
Scott

Dan Marotta

January 6th 17, 01:58 AM

I think the original poster of that description was referring to my
Stemme S10-VT
<https://www.dropbox.com/s/vyx7bkqzjqfiipt/IMG_20160327_100018984.jpg?dl=0>
which has conventional landing gear, i.e., two main gear and the tail
wheel. Sitting on three wheels, it's pretty level though the 75 foot
wings can rock up and down quite a bit in winds.

On 1/5/2017 11:47 AM, SF wrote:
> OK, I'll Bite, WTF is a self leveling glider?
>
> After our Grob's encounter with a runway light, we no longer condone attempting to roll off the runway in a club ship. Stop it on the runway, get out, and push it off. Not a 100% guarantee, but the collision speed will be much lower.
>
> SF

--
Dan, 5J

bumper[_4_]

January 6th 17, 07:37 AM

On Thursday, January 5, 2017 at 5:55:27 PM UTC-8, Scott Williams wrote:
> Stemme gliders run in the $250,000 range, color me jealous.
>
> Good Lift,
> Scott

Scott,

Maybe 15 years ago . . . a new Stemme will be about $400,000 base price now, so add about 40K more for average equipped. Your jealous color will be well hidden beneath that mound of cash.

bumper
MKIV high tech yaw string and QV

January 6th 17, 05:28 PM

Got it, I have one flight in a Stemme, Now that I think of it, it was sorta self leveling. Wouldn't be the first description of it that would come to mind though.

While we are at it Don't forget the Caproni's two side by side main wheels. I have one flight in that one. I remember thinking that the Caproni may be the only glider I know of that an experienced pilot couldn't land safely without several instructional flights first. And, the only glider I know that the vario is the only indicator you have for detecting 5 Kt. thermals. The Caproni didn't see to offer any clues via the seat of the pants at all when we ran through one.

Neither of those flights left me with a burning desire to go out and buy either one. I prefer smaller and lighter.

SF

Tango Whisky

January 6th 17, 08:22 PM

After about 600 hours in a Caproni 21S, I don't know what you are talking about...

John Cochrane[_3_]

January 6th 17, 11:02 PM

Seriously, retractable pogo sticks are not such a bad idea...

After a few contest crashes in the early 2000s involving full water, cross-downwind, high heat, high altitude takeoffs, and ineffective wing-runs it occurred to a number of pilots that the concept "run the wingtip" started in KA6s, and sooner or later there is a limit. There was a lot of discussion about ATVs, roller blades, launch devices, but perhaps that was over beers on rest days. In any case it didn't go anywhere.

Retractable pogo sticks or wing wheels would pretty much eliminate wing drop on takeoff crashes, ground loops, etc. And on landing too.

John Cochrane

Steve Koerner

January 7th 17, 04:30 PM

But John, wouldn't a pogo stick make it difficult to do directional corrections or turn off the runway or compensate for crosswind?

I'm thinking my gas jet would leave the pilot with more control on the runway and would probably be a lesser burden to include in a wing (cheaper).

John Cochrane[_3_]

January 7th 17, 04:52 PM

Good question. I was thinking mostly of preventing wing down groundloops and loss of control. There, having a pogo stick that lets one wing be, say 3 feet off the ground and the other up lets you keep upwind wing down. Directional control is usually by rudder, not putting a wing down -- that's when you lose control!
Such pogo sticks need not be at the tips. They could be attached mid span.
But I like the jets idea. Since this is about preventing a rare loss of control event, you don't need much. But you do need some -- maybe 100 lbs of force for a few seconds. And how do you keep it from getting too much momentum and pushing the other wing down -- needs delicate control.
Wing drops on takeoff are a continuing problem at conteststs. Yes it's minor, only one major incident so far (tonopah), but that's more because we are careful to keep spectators out of the way of the errant gliders.

Tango Eight

January 7th 17, 04:59 PM

On Saturday, January 7, 2017 at 11:30:04 AM UTC-5, Steve Koerner wrote:
> But John, wouldn't a pogo stick make it difficult to do directional corrections or turn off the runway or compensate for crosswind?
>
> I'm thinking my gas jet would leave the pilot with more control on the runway and would probably be a lesser burden to include in a wing (cheaper).

https://en.wikipedia.org/wiki/Cold_gas_thruster

run the numbers on specific impulse.

best,
Evan

Steve Koerner

January 7th 17, 06:55 PM

> https://en.wikipedia.org/wiki/Cold_gas_thruster
>
> run the numbers on specific impulse.
>
> best,
> Evan

Damn. I knew somebody would do that to me. OK then, here goes some crude top level physics...

I'll start with my own guesstimation that 15 lbf near the wingtip for 3 seconds will be enough to get over the runway light. That's an impulse requirement of 45 lb * sec.

I don't know anything about designing nozzles but for the sake of argument, I will send my gas out at 89% of the speed of sound = 1000 ft/sec.

Impulse relates to change of momentum as J = delta m * v. Solving for the mass of gas flow required: m = J/v = 45/1000 = .045 slug.

The density of plain air at seal level is .00238 slug/cu ft. But sense we're using oxygen instead of air, we get a bit more density, like .0027. So to relate the required mass to the sizing of oxygen bottles as we are normally familiar with: .045 slug / (.0027 slug/cu ft) = 16.7 cu ft. Doable! You saved your wing for the cost of an oxygen refill.

[email protected]

January 8th 17, 12:56 AM

Steve, the wing's full of water, so mix some of that in with the O2 and you'll have a more massive jet.

-Tom

On Saturday, January 7, 2017 at 10:55:39 AM UTC-8, Steve Koerner wrote:
> > https://en.wikipedia.org/wiki/Cold_gas_thruster
> >
> > run the numbers on specific impulse.
> >
> > best,
> > Evan
>
> Damn. I knew somebody would do that to me. OK then, here goes some crude top level physics...
>
> I'll start with my own guesstimation that 15 lbf near the wingtip for 3 seconds will be enough to get over the runway light. That's an impulse requirement of 45 lb * sec.
>
> I don't know anything about designing nozzles but for the sake of argument, I will send my gas out at 89% of the speed of sound = 1000 ft/sec.
>
> Impulse relates to change of momentum as J = delta m * v. Solving for the mass of gas flow required: m = J/v = 45/1000 = .045 slug.
>
> The density of plain air at seal level is .00238 slug/cu ft. But sense we're using oxygen instead of air, we get a bit more density, like .0027. So to relate the required mass to the sizing of oxygen bottles as we are normally familiar with: .045 slug / (.0027 slug/cu ft) = 16.7 cu ft. Doable! You saved your wing for the cost of an oxygen refill.