The Technical Questions Thread

[NSXType-R]

I don't want to start a new thread each time I think up of a technical question, so I'll start this thread. Sometimes, random things trigger these questions and I can't stand not having an answer.

So far, I only have one question, but I'm sure more will come.

Last night there was a mighty big thunder storm (it actually woke me up, so it's pretty big) and I decided to watch it. So, I saw a couple of airplanes go by actually, while the big thunder bolts were flying. My question is, how do planes keep themselves from getting zapped?

[derekthetree]

Lightning tries to find the easiest route down to the ground, and I would have thought that striking a plane wouldn't help it in that sense, but I'm sure someone can give you a better answer!

[coolieman1220]

lol! oh man good answer. i guess it's kinda like striking a car

[Cyco]

Planes do get zapped, and regularly.

It does affect them, but as they are not earthed it is not normally critically damaging.

[NSXType-R]

Originally Posted by Cyco

Planes do get zapped, and regularly.

It does affect them, but as they are not earthed it is not normally critically damaging.

It isn't grounded, so it's safer that way? That doesn't make sense. Lightning rods are grounded for a reason. Can someone explain this to me? I absolutely suck at electricity.

I see. It must be really scary to be in a plane and have a major thunderstorm happen all around you.

The electronic components can potentially still fail though, right? I don't know how much energy it packs, but it's a heck of a lot for a flying aluminum can, especially when it's loaded with fuel.

[digitalcraft]

http://www.usatoday.com/travel/colum...-captain_x.htm

It has been decades since commercial airlines sustained any real damage from a lightning strike, even though statistically airliners experience an average of one to two strikes per year per plane. You would probably be hard-pressed to find an experienced pilot who hasn't experienced at least one or more strikes somewhere along the way.

Lightning strikes on aircraft occur when negatively charged electrons encounter positive charges from the surface of the plane, and when they do, ZAP!—lightning occurs. Airplanes create charges in both directions and act as a conduit for lightning.

There are stringent FAA requirements for lightning certification. Surge protectors and shielding are installed to protect avionics.

So what happens when lightning actually strikes the airplane? It's important to note that lightning has one mission in life and that is to find a path to the ground. It usually strikes an extremity like the nose or wingtip, and from there it passes harmlessly around the outside of the aircraft and exits off the back of the wings with the help of "static wicks."

Static wicks don't prevent lightning strikes but give the electrical charges an easy exit point. There are a minimum number of static wicks required to be on the airplane and if any are missing, they must be replaced before flight.



Hope that answers your question!

[NSXType-R]

Thank you very much. So it just slides around the airplane.

[Alastor]

Originally Posted by NSXType-R

Thank you very much. So it just slides around the airplane.

Lighting is more of an issue on aircraft that use non-conductive composite structures. For these aircraft a conductive path has to be added, such as a wire mesh over the composite parts.

Without a low resistance path the lightning could potentially create holes in the material or worse.

[Kitdy]

Hijack time.

Why does this engine have the 6 exhausts or whatever the chrome things are in a row when it is a V6? Wouldn't it be more normal to have three on each side? Am I crazy? Is this peculiar in any way? Help!

[drakkie]

Originally Posted by Kitdy

Hijack time.

Why does this engine have the 6 exhausts or whatever the chrome things are in a row when it is a V6? Wouldn't it be more normal to have three on each side? Am I crazy? Is this peculiar in any way? Help!

I'd say it has two exhaust valves per cilindre and therefor one pipe for each valve...

[Jack_Bauer]

Originally Posted by Kitdy

Hijack time.

Why does this engine have the 6 exhausts or whatever the chrome things are in a row when it is a V6? Wouldn't it be more normal to have three on each side? Am I crazy? Is this peculiar in any way? Help!

The chromed pipes are the induction pipes, not the exhaust. You can just about see the exhausts on the nearside bank of cylinders, the red curved pipes below the cylinder head cover, and it will indeed have three exhausts on each side.

[jediali]

Actually the 6 intake pipes leave from a common plenum and go down into the V6 to deliver an inlet to each combustion chamber as in:


This is a very pretty engine!

[nota]

Originally Posted by Kitdy

Hijack time.

Why does this engine have the 6 exhausts or whatever the chrome things are in a row when it is a V6? Wouldn't it be more normal to have three on each side? Am I crazy? Is this peculiar in any way? Help!

Those 6 eye-appealing tubes are part of the induction system, they each feed down into a continuation of separated ducts (moulded internally in the intake manifold, situated between the 'V') which distributes the intake flow left/right into each respective cylinder

[culver]

For their next trick they can explain why this V6 has 12
http://www.members.cox.net/rdgrauman/finiahed2.jpg

(PS, the 2.5L Ford Duratec V6 has 12 for the same reason)
http://www.supercars.net/servlets/PW...esey/4car1.jpg sorry the engine is a bit dirty in this picture

[Jack_Bauer]

Originally Posted by culver

For their next trick they can explain why this V6 has 12
http://www.members.cox.net/rdgrauman/finiahed2.jpg

(PS, the 2.5L Ford Duratec V6 has 12 for the same reason)
http://www.supercars.net/servlets/PW...esey/4car1.jpg sorry the engine is a bit dirty in this picture

Variable length intake manifolds.

There is a long and a short pipe for each individual cylinder, and the intake switches between the two depending on revs - long pipe for low revs and short pipe for higher revs (I think!).