Taxi/Landing Lights on Cowl vs Wing

[455 Bravo Uniform]

No, it's not about lamp longevity.

Mostly for entertainment, nothing more:

-How much less light, quantitatively, does the cowl mounted lamp project than the wing mounted, as a result of the passing blade?

-Do 2 bladed props allow more light to pass than a 3?

-What about any "phasing" of the prop to the lamp? I am guessing that incandescent lamps and/or DC power will have the lamp "constant on" with no cycling like other lamps or AC power (i.e., 60 Hz). Is that true with LED lamps as well?

What I was thinking, and why this was just an entertainment post, if the lamp was on AC power, and the RPMs of the passing blade matched the lamp phase, you'd have no runway illumination or 100% illumination depending on how the phases overlapped.

Lastly, I know I can search the web, but what was the mechanics behind nose mounted guns on military aircraft that were phased to miss the prop blade? And what planes were like that?

Too much time on my hands. Good weather, but no flying due to untrustworthy ASI on my plane and no mechanic can look at it until next week.

 

[GRG55]

...Lastly, I know I can search the web, but what was the mechanics behind nose mounted guns on military aircraft that were phased to miss the prop blade? And what planes were like that?

Too much time on my hands. Good weather, but no flying due to untrustworthy ASI on my plane and no mechanic can look at it until next week.

Mostly WWI and immediate post-war combat aircraft. Synchronizers were originally mechanical interrupters, the first attributed to Antony Fokker. The Brits, being Brits, decided to make a hydraulic system instead.

A few examples: the Fokker Eindecker (believed to be the first system to see field service in quantity), Albatross D.5 as well as the Sopwith Pup, Camel and Triplane.

 

[James331]

For a single engine plane wing is much better for night or IMC, just because of having the prop arch crap during approach and landing.

 

[Tantalum]

I've wondered the same as well, I happen to think wing mounted lights look a lot better overall

 

[Dana]

Incandescent bulbs emit light because the filament is white hot. Even on AC, the filament doesn't cool enough between cycles to make a noticeable difference in light output.

LED or fluorescent is another story. LEDs run on DC only (AC LEDs have a built in rectifier but rarely smooth it, so the LED sees a rippling DC).

 

[brian]]

152 at 025

Switching to guns. .... Um I'll turn on the light so we can see each other.




My guess is that it is easier to mount lights in the wings. The issue (at least from the bonanza history) was the trade magazines kept commenting that the light from the wing mounted lights affected the pilot. I've heard that nose mounted lights just work better.

It does feel cool turning on the wing mounted lights at night. Next chance I'll get I'll switch to led. Having one on all the time does get you noticed better for see and avoid.

 

[Lachlan]

If you're already on a treadmill going the speed of light, it won't matter if you turn on landing, nav or anti-collision lights. They won't go anywhere. It's like peeing money into the wind by spending cash on LED lights, soooo...

 

[JCranford]

Synchronizers were originally mechanical interrupters, the first attributed to Antony Fokker.

Actually the 'first' were simple 'V' shaped metal deflectors attached to the back of the prop that deflected the rounds that would have hit the prop. Synchronizers came later

 

[Clark1961]

If you're already on a treadmill going the speed of light, it won't matter if you turn on landing, nav or anti-collision lights. They won't go anywhere. It's like peeing money into the wind by spending cash on LED lights, soooo...

why would you need lights on a treadmill?

 

[Kiddo's Driver]

I like lights on the wing better. I don't see them unless I turn to check and make sure they are on so they are not distracting while I am in route. They are LEDs so I leave one or the other on all the time. Both of mine are mounted on the port wing. I wish I had one on each wing.

 

[MauleSkinner]

why would you need lights on a treadmill?

The aerodynamic effects are different if you can see what's happening...kinda like a downwind turn.

 

[Clark1961]

The aerodynamic effects are different if you can see what's happening...kinda like a downwind turn.

I'm calling BS. No lights are needed because everybody just stares at the TV while on a treadmill. Someday maybe somebody will even turn the TV on.

 

[Skip Miller]

Incandescent bulbs emit light because the filament is white hot. Even on AC, the filament doesn't cool enough between cycles to make a noticeable difference in light output.

LED or fluorescent is another story. LEDs run on DC only (AC LEDs have a built in rectifier but rarely smooth it, so the LED sees a rippling DC).

-Skip

 

[Tantalum]

If you're already on a treadmill going the speed of light, it won't matter if you turn on landing, nav or anti-collision lights. They won't go anywhere.

Does a frog infinitely jumping only half the distance to the end of the log ever get to the end of the log?

A little bit of cross thread posting here, but stackexchange (or its child, stackoverflow) came up in another thread about douche-bag pilots and mean forums... it's a fun thought experiment:
https://physics.stackexchange.com/q...ing-speed-of-the-moving-train-if-im-inside-it

 

[Tantalum]

Incidentally.. I am not sure if it is just me, but the LED strobes seem remarkably underwhelming. I miss the bright flashing strobes, the new LED strobes seem very pibsqueek. It could just be my eyes but a Cherokee with old style strobes seem more brilliant in the night sky than 737s with the LED strobes

 

[RyanB]

I've always preferred to have it on the wing, but as far as two blade vs. three blade making a difference, there isn't much of one. They'll both emit about the same amount of light, except you'll notice it a bit more at lower RPM's on the three-bladed prop.

For a single engine plane wing is much better for night or IMC, just because of having the prop arch crap during approach and landing.

Agreed.

 

[Clark1961]

Does a frog infinitely jumping only half the distance to the end of the log ever get to the end of the log?

A little bit of cross thread posting here, but stackexchange (or its child, stackoverflow) came up in another thread about douche-bag pilots and mean forums... it's a fun thought experiment:
https://physics.stackexchange.com/q...ing-speed-of-the-moving-train-if-im-inside-it

View attachment 55371

Where did you go wrong? You posted on POA, you got outta bed, you read a forum other than POA,.....really the list of where you went wrong is endless.

 

[mtuomi]

If you're already on a treadmill going the speed of light, it won't matter if you turn on landing, nav or anti-collision lights. They won't go anywhere. It's like peeing money into the wind by spending cash on LED lights, soooo...

I don't think you understand general relativity very well. The light does go, actually, it goes at the speed of light.

 

[Lachlan]

I don't think you understand general relativity very well. The light does go, actually, it goes at the speed of light.

I understand it very well. Now that my wife and I have moved back to the small town where I grew up (pop. 614, one grass airstrip, 11 airplanes, 6 bars) we seem to be generally related to nearly everyone in town. Or know their relativity and kin.

 

[Clark1961]

I understand it very well. Now that my wife and I have moved back to the small town where I grew up (pop. 614, one grass airstrip, 11 airplanes, 6 bars) we seem to be generally related to nearly everyone in town. Or know their relativity and kin.

Just remember that incest is relative.

 

[JonH]

Speaking of LEDs on airplanes, can you believe this guy had warp nav sensors installed right next to his strobes? That has to cause interference, especially at warp speeds.

 

[Lachlan]

Just remember that incest is relative.

What do your relatives and yeast have in common?



They're both in bread.

 

[Lachlan]

why would you need lights on a treadmill?

To see the AOA indicator better.

 

[zaitcev]

Lastly, I know I can search the web, but what was the mechanics behind nose mounted guns on military aircraft that were phased to miss the prop blade? And what planes were like that?

The WWI period synchronizers were facilitated by the fact that the Maxim design differs from conventional machine guns that came later in that it fires from the closed breech and uses a somewhat involved mechanism that releases its striker, with a hammer and a transfer cam. An additional cam was installed in parallel with the transfer cam, so that one of the two interacted with the transfer bar from the trigger and one interacted with an equivalent transfer bar from the prop. A large diameter cam on the prop drove the extra bar through a series of linkages. To fire the gun, both bottom cams had to be advanced simultaneously.

 

[Dan Thomas]

The OP didn't care about the longevity concerns of wing- or cowl-mounted lights, but I do. Those incandescent lamps have a rated 25-hour life. In the cowls of the 172s I looked after, we got as little as four flight hours out of them. And they weren't even on for the whole four hours. The cowl vibrates and shakes in the prop blast, the baffle seals rub on it with engine vibration and shake it, and the huge noise factor has to come into play as well. Out on the leading edge, a long way from the engine and prop, they last longer. A lot longer.

But still only 25 hours. If you are a commercial operator and fed up with the cost of replacing lamps (parts and labor), go for the LEDs. They are rated for 1000 hours and will probably go longer. They don't have fragile little filaments to break with vibration. They use less than a fifth of the current, meaning that switches last longer.

 

[GRG55]

Actually the 'first' were simple 'V' shaped metal deflectors attached to the back of the prop that deflected the rounds that would have hit the prop. Synchronizers came later

I am aware of that. But the OP specifically asked "...but what was the mechanics behind nose mounted guns on military aircraft that were phased to miss the prop blade?"

 

[RudyP]

I like both! HID in the cowl and triple LEDs in each wingtip give a nice wide and powerful amount of the light. My main (cowl) light is low enough that I really don't see anything reflected in prop arc.