Retractable Landing Light

[f1rocket]

Anyone designed and installed a retractable landing light in the fuselage? I'm thinking of duplicating the Long-EZ design for this and was wondering if anyone else had already done so?

The Long-EZ design is pretty simple with a throw-over handle which locks the light in both the up and the down position. One of the few people who can compete with Van for simple and elegant designs is Burt Rutan.

Before you respond with the "put it in the wing dummy, like a thousand people before you" post, I have my reasons for wanting it in the fuselage. The Rocket EVO wing is pretty narrow up front, access is limited, and I don't really like them out that far from the centerline (among other reasons).

Any lessons learned from people who have already thought of this but discarded it would be appreciated before I go and design the mechanism. Thanks.

 

[Randy Walls]

Good idea

I think that is a great idea, unfortunately I have no info.

 

[flyboykelly]

I am looking at doing the same thing, though in the wing. I was thinking of installing one under each wing in one of the access panels. That way if they need maintenance all I have to do is undo the panel and I can work on it on a bench instead of on the aircraft. Does the EVO wing have simiar access panels?

 

[Ironflight]

I've seen a couple of neat HID installations in the engine cooling air inlets Randy - not as "trick" as a retractable mechanism, but they looked to be pretty simple, and keep the lights out of the wings. I shudder to remember how often my Grumman ate the cowl-mounted (and vibration-prone) landing lights, but perhaps the new style bulbs can handle it better.

Paul

 

[roee]

Use a servo motor

No personal experience with a retractable light, but I could think of a few ideas. Firstly, I'd consider actuating it with something like a MAC servo, rather than a mechanical handle and catch.

[I should disclose that I am an electrical engineer, so I do have some bias on the subject ;-) ]

Likely advantages to the servo approach:
- The installation will be lighter weight.
- The installation will be mechanically simpler.
- No additional handles cluttering up the cockpit.
- The installation can go just about anywhere, including places where a mechanical handle would be inconvenient or impractical.
- If you're really ambitious, it could have intelligently variable incidence angle. For example, if you design it to pivot down from the bottom of the fuselage, you could set different optimal incidence angles for taxi, takeoff, or landing. If you were even more ambitious, you could have it auto-adjust the light incidence angle based on aircraft attitude from your AHRS. Neato!

Likely disadvantages to the servo approach:
- Cost of the servo.
- Added electrical complexity.
- The actuation will be electrically dependent, but then again, so is the light bulb. The only undesired scenario I can see with this is if you experience an electrical failure while the light is deployed. Then you wouldn't be able to retract it, and will have to put up with the added drag for the remainder of the flight. With a full electrical failure, you'll want to terminate the flight as soon as practical anyway, so I don't think the extra drag from the light fixture is major concern.

Hey, I like it! Having said all that, I think I'll still install my own landing lights in the conventional way in the wings. I've got enough little custom touches like this already...

-Roee

 

[RV7Guy]

Retractable in cowl

Hi Randy,

I have plans to make mount at least one in the cowl using the MAC servo as the actuator. The light/door will be mounted to a retractable landing gear device from my box of RC goodies. This will give a positive lock in both up and down positions. When down, it will also serve as a cowl flap!!!

The light itself will be the Creative air LED light. (tentatively)

I also plan to flush mount the same light in the LE of the wing tips.

 

[lancef53]

I would love to see some info on it, I was thinking a cowl mounted light, but retractable sounds even better.

Lets keep this alive!!

 

[f1rocket]

Thank you for some very creative ideas! I am trying to stay away from a servo-style implementation because it is more complicated and costly than the Long-EZ mechanism, which is dumb-$ss simple. However, it has the disadvantage of requiring the handle directly above the light so placement becomes an issue. A servo-based solution makes it possible to install anywhere so I may come back around to this.

In looking at servos, the MAC servos are too slow. The biggest servo they have takes 17 seconds to fully extend only 1.2 inches. I'm not aware of other servos out there.

Darwin, I like the idea of having locking mechanisms in both the up and down configuration. I will need to check into that. Do you have a link to a source where I could check this out?

If I could get it to fit within the size of the wing inspection plate, I might have something that others might be willing to purchase. Interesting. Stay tuned, I plan to work on some designs to see if I can come up with something that's not too complicated or expensive.

 

[pierre smith]

Air Tractors.....

....have retractable lights under the wings. www.airtractor.com

Regards,

 

[Kyleag04]

Just be careful

I am looking at doing the same thing, though in the wing. I was thinking of installing one under each wing in one of the access panels. That way if they need maintenance all I have to do is undo the panel and I can work on it on a bench instead of on the aircraft. Does the EVO wing have simiar access panels?

Retractable landing lights are handy, but be sure you think about the failure modes. If you've got one light under each wing and you have an actuator failure, and one light comes up and the other stays down, how much rudder is that gonna take to counteract that drag?

As Pierre says, the Air Tractors have large retractable landing lights under each wing near the tips. There have been a few cases where one light will fail in the extended position and it takes a lot of rudder to keep the airplane controllable.

Just something to think about.

 

[ichibanmarin]

Randy ....

I designed and installed a retractable landing light on my RV-4 that utilizes a 75 watt halogen MR-16 spot as the light source. It is hinged on the bottom of the engine cowel and is actuated by a Ray Allen servo. When I turn on the landing light switch it starts the light and servo simultaneously and at the end of the servo travel it stops with the light still on. When I turn off the switch the light goes off and the servo automatically returns the hinged lamp assembly to its nesting position.

If you are interested I probably could send you a pix of the installation.

Bill Darnell
RV-4 N459B
(559)288-6039
[email protected]

 

[ichibanmarin]

I designed one for my RV-4 that utilizes an MR16 75 watt halogen spot for a light source and a Ray Allen servo for an actuator. It is mounted on the bottom cowl. When I turn on the landing light, the lamp lights and the hinge mounted assembly deploys to the full travel of the servo and stops. When I turn off the light the servo automatically returns the assembly to its nesting position.

Let me know if you would like pix of the installation.

Bill Darnell
RV-4 N459B
(559)288-6039
[email protected]

Anyone designed and installed a retractable landing light in the fuselage? I'm thinking of duplicating the Long-EZ design for this and was wondering if anyone else had already done so?

The Long-EZ design is pretty simple with a throw-over handle which locks the light in both the up and the down position. One of the few people who can compete with Van for simple and elegant designs is Burt Rutan.

Before you respond with the "put it in the wing dummy, like a thousand people before you" post, I have my reasons for wanting it in the fuselage. The Rocket EVO wing is pretty narrow up front, access is limited, and I don't really like them out that far from the centerline (among other reasons).

Any lessons learned from people who have already thought of this but discarded it would be appreciated before I go and design the mechanism. Thanks.

 

[RV7Guy]

Helicopter links

Google search food for thought. Lots of helicopters use these, the servo is very nice on a coolie hat.

On the two helicopters I fly, (Bell 407 and Astar 350) they both have retractable lights. They are painfully slow but that isn't really an issue. They are really bright.

Knowing the high cost of FAA certified parts, these are probably thousands of dollars.

 

[RV7Guy]

Don't over think this

Retractable landing lights are handy, but be sure you think about the failure modes. If you've got one light under each wing and you have an actuator failure, and one light comes up and the other stays down, how much rudder is that gonna take to counteract that drag?

Haven't really seen too many servo failures. I don't think the extra drag would be significant. This is one reason I thought of putting it in the cowling, closer to the CL.

 

[RV7Guy]

Links

In looking at servos, the MAC servos are too slow. The biggest servo they have takes 17 seconds to fully extend only 1.2 inches. I'm not aware of other servos out there.

Darwin, I like the idea of having locking mechanisms in both the up and down configuration. I will need to check into that. Do you have a link to a source where I could check this out?

If I could get it to fit within the size of the wing inspection plate, I might have something that others might be willing to purchase. Interesting. Stay tuned, I plan to work on some designs to see if I can come up with something that's not too complicated or expensive.

Hi Randy,

I'm not too concerned about the speed of the servo for a landing light. Certainly, faster would be desirable.

Here's some thoughts.

1) A MAC servo driven assembly with direct hook up would provide the ability to choose a setting btwn both ends. Simple and relatively light. Downside, slow and the servo is carrying the load.

2) A mechanical interface using a RC landing gear system would give locking at each end without stress on the servo. The down side is most of these systems have no "middle." It is either up or down.

3) There is a RC landing gear system that is pneumatic. This is a simple system that is very light and easy to actuate. Up to down is about 1 second. The down side, again, no middle or adjustment.

4) Not sure you could contain everything within the dimensions of the inspection plate but that is a great idea.

Go to www.towerhobbies.com and search for Retractable Landing gear. You'll get a bunch. I'll try to break this down some more later.

Using the RC gear, you should be able to do two lights for under $150 not including the servos or lights.

The other possibility is using RC servos. I have a couple of high torque RC servos that actually have more torque than the MAC servos. I'll look into that as well.

 

[Bill Wightman]

Would it be possible to stick a couple of the new compact HID's behind the wing root fairings? The Boeings all have ldg lights there.

 

[Little_Richard]

The biggest thing you have to be careful of is getting reflections off the back of the prop. That is the biggest reason I beleive most lights are located in the wing.

 

[Rick S.]

Just a thought but using a push/pull cable attached to a bellcrank at the hinge line that would rotate the light down and out. Mount the knob on the panel or the best reached location and you could snake the cable fairly easily all the way to the light. Use a N.C. paddle switch that is actuated by the bellcrank that turns on the light as it move out of the well into the airstream. Funny I was reading this and right away thought of a servo, but if you loose eletrical power the servo might not work...but neither would the light depending on how it was powered.

 

[Rick S.]

Hi Randy,


3) There is a RC landing gear system that is pneumatic. This is a simple system that is very light and easy to actuate. Up to down is about 1 second. The down side, again, no middle or adjustment.

I thought about that too...but are you gonna pump up your landing light tank for every flight and what about duration? I had both Rhom-airs and spring air retracts before...spring airs would at least deploy when the air ran out...Rhom-airs would just sag..I'm not even sure the Rhoms are still made...I may be dating my R/C experience...There are a bunch of stout servos made for R/C use. A sail winch might be your only real choice, the coreless BB servos, although very fast and strong will require constant power to maintain position due the indirect drive and potentiometer telling the motor where to hold position. The cheaper servos will hold position without power but I don't think the gear train could handle the force of the light being deployed into the air. But heck this is a neat idea to brainstorm.

 

[mburch]

Guys,

Just wondering, wouldn't the servo have to do a lot less work against the airstream if you oriented the hinge line parallel to the aircraft's longitudinal axis? Then the light could drop down like the main gear on a P-51, instead of like a speed brake. Just a thought.

cheers,
mcb

 

[hcccs]

I am planning the installation of the landing/taxi lights on my RV-4 and I was thinking of placing two 75W MR16s in the cowl on either side of the spinner. There is not much space there and pehaps retractable lights could work. They would then be out of the way of the propeller. I think I would go for RC model servos instead of Ray Allen ones because of the lower cost and they react really fast. It would be interesting to your installation - could we have some photos?

 

[SteinAir]

Would it be possible to stick a couple of the new compact HID's behind the wing root fairings? The Boeings all have ldg lights there.

Or in the leading edge of a wheelpant? Granted, not very high above the ground, but once you'r on the ground it's not nearly as important. I think this is my only option on the Mullicoupe...no retractable lights for me!

Cheers,
Stein

 

[aerhed]

Adustable 500W

N23PW (RV4) has an electrically adustable 500 watt belly light from some kinda agplane. Works good. The drop down lights on twin Cessnas are notorious failers.

 

[Wayne Gillispie]

Or in the leading edge of a wheelpant? Granted, not very high above the ground, but once you'r on the ground it's not nearly as important. I think this is my only option on the Mullicoupe...no retractable lights for me!

Cheers,
Stein

I was thinking the same thing for my 10. I will install the wing tip hid's but wanted a little more without cutting into wing l.e. May have to beef up the wheel pant and learn how to mold a lens. Fun, fun.

 

[Scott Hersha]

OK, here's my idea: Cut a rectangular hole in the belly on the centerline under the box that I believe is between your legs in the Rocket (?). The light will move down through the rectangular hole into the slipstream and back up into the fuse vertically, actuated manually on an 'L' shaped brackett. The light will nest between the legs of the 'L' with a rectangular al. plate on the outside leg of each L flange to close off the hole in the extended and retracted position. The fixture will rotate on a shaft (bolt) at the apex of the 'L'. The manual extension will be via another aluminum piece for a handle attached somewhere near the apex of the 'L' and extending into the cabin a short ways (between your legs). Locking it up or down should be easy to figure out and should only take about a second to extend/retract. That's what I'd do if I was building a Rocket. I can picture it in my mind.... wish I was building a Rocket....

Scott
RV-8 Fastback

 

[benamyava]

GM has a retract system for this project.

$35 and General Motors has a retractable side mirror for its trucks and SUV's. How about using the unit mechanism and installing a light instead.


http://www.autopartswarehouse.com/p...d=X1093010841W41260599c6350&apwkwd=gm+mirrors

The B727 and B737 use retractable landing lights in the mid wing area. The only limitation is 250K. Above 250K the lights hang fine and work but the ailerons buzz a little. Works good.

 

[N8RV]

An epiphany!

Randy, I don't know if you've gleaned any good ideas from this thread about your retractable landing light concept, but I sure picked up a doozie ...

I've been struggling with controlling my Van's oil cooler shutter to adjust oil temps. I've tried three different push-pull cables and still am not satisfied. However, I do have a Ray Allen servo sitting unused at the hangar, along with the rocker switch. I could mount the servo on a bracket by the shutter and control the shutter ELECTRONICALLY instead of mechanically.

Simply BRILLIANT! Thanks for the thread.

 

[Shockwave]

$35 and General Motors has a retractable side mirror for its trucks and SUV's. How about using the unit mechanism and installing a light instead.

Now there's a thought, why not snag the whole retractable light assembly from a Fiero?