Why do airplane noses have lines on the front?
I was under the impression the radar is up there so I assume it might have something to do with that?
Looks to me like that’s just where the nose is riveted to the structure underneath.
Sometimes they have access panels but in the linked pictures they look just like the lines where the various panels that make up the nose were riveted together.
Here’s what a 747’s nose looks like opened up. You can see the rivet lines inside the nose cone.
Here’s another example, though you can’t see the inside of the radome.
http://www.sae.org/dlymagazineimages/11321_14605_ART.jpg
And another example:
http://atmospheres.gsfc.nasa.gov/jpserver/data/CAR_P-3B-Integration.data/size_1/CAR:P3-radome[5]-Feb19-2008.jpg
An F-16 with its radome opened up:
They are static dissipaters and/or lightning diverters. The radome is nonconductive (to allow the radar to pass through), so static will build up on its surface. The strips conduct the static charge back to the rest of the fuselage.
Are they actually rivets? Wouldn’t rivets interfere with radar transmission/reception?
Aren’t they gussets, to add structural integrity to the cone shape?
On some of the aircraft that I worked on, they were screws.
As far as interfering with the radar transmission, not much. It would be like a speck of dirt on your glasses, or a bug splat on a windshield. You can still see what is ahead.
I worked on some military aircraft with really powerful radar systems. It was something to see when an SOS or Brillo pad would go up in flames 50 feet from the radar when it was turned on.
Then, you might sometimes see airplanes with something like this on the nose cone.
This is a WAG, so I was holding off to see if someone who actually knew would chime in: They look about the right length to be VHF antenna elements. Since the aircraft skin is mostly aluminum, you would need to have a drag inducing blade antenna sticking out to avoid the skin shielding it. But the nose cone is a dielectric radome, so you can flush mount radiators on it. Again, this is speculation.
KCB615 had it with the only reasonable sounding answer and an actual link.
This.
More cites:
www.radome.com/generic.aspx?id=197270
http://www.lightningdiversion.com/Strips.htm
Thanks for the answer and the links KCB615 and StrangerThanFiction.
Ignorance fought!
The anti-static strips sounds right to me. The radomes are made as a single piece of fiberglass. I’ve been in a facility in Tulsa that replaces airplane parts that have been damaged - largely due to bird strikes. You might see a front flap piece in there with a big dent, and blood and feathers still stuck to it. The area I was there for was specifically for the radome testing - they had fiberglass molds to build radomes for each of the airliners. After building each one, they subject it to radar testing to make sure it won’t interfere with the radar signal, and this testing is done in a big anechoic indoor radar chamber.
I’m pretty sure that rivets would be an issue for them, especially a row of rivets - they’re pretty particular about the characteristics of the fiberglass.
I take it you didn’t want to be downrange either… or was it somehow not harmful to living things?
Might make for a really interesting pot roast sometime though.
No, it’s dangerous to people as well. Our aircraft limitations specify that we can’t operate the radar on the ground if there are personnel within 49 feet or fueling operations within 300 feet of the front of the antenna. It’s a 10kW transmitter operating in the microwave band at approx 9.4 GHz. Think of it as basically a large, powerful microwave spotlight. I certainly wouldn’t want to be in front of it while it’s radiating.
49 feet? I have to know - how did they find out 50 feet just wasn’t safe enough?
On the F-111 we’d put out warning cones 75 feet away for the attack radar and 50 feet for the terrain following radar.
Trial and error.
Hi JerrySTL!
Where were you where you worked on F-111’s?
We had them at Mt. Home AFB, Idaho.
Just FYI, the weather radar in commercial airliners’ noses is much less powerful, much less dangerous, and much less “focused” than a target-acquisition or terrain-following military radar.
The radar in an airliner is designed to reflect moisture - specifically the water in cloud formations and thunderstorms. This is a very basic, crude form of reflectivity.
The aforementioned “attack radars” in F-111s and other fighters (let’s not get into whether the F-111 was a fighter) can do things as specific as determine the type of aircraft it is facing by counting the blades of the compressor in the opposing aircraft’s engine.
Likewise, terrain-following radar not only has a faster “sweep” (you need to paint that ground often when you are at 200 feet and 500 knots) but a much more powerful emitter, because you must distinguish small variations very accurately.
Lots of energy, directed in many different directions = danger to people on the ground.
But for commercial airliners - ehh. You would be surprised at how small the radar emitter is in some airliners. The nose is there for aerodynamics, the static strips are there for static energy dissipation, and the radar emitter sits snugly underneath.