[Robert A Cook PE]

Kathy.

Didn't see an answer to your question about the "sharp thingie" on the nose of the "Thunderchief" fighter jet.

You'll see them sticking out like on many of that era's supersonic and transsonic fighter jets:

There is no way to use a speedometer on an airplane of course: no tires!

But the pilot HAS to know his speed for navigating and planning missions, and to check against stalling. So, the designers stick a pipe into the airstream, and mesure how much force the air flowing down the pipe pushes against the little meter. Depending on air pressure (which varies with altitude and temperature) they then calculate speed and display it on the cockpit instruments. (All this instrumentation is part of what costs so much...)

To get airspeed indication, you have to "sample" the air well away from the front of the wing or fusalage, or the shock waves bounce around the tube and give you bad readings that jump up and down randomly.

So they stick the probe (the pipe) way out front of the jet. Since anything that sticks out creates drag, they have to make a stick point to reduce drag as much as possible.

Slower jets (like commercial ones) and prop airplanes are slow enough that the designers don't have to worry about supersonic shock waves hitting the instrument pipes, so they use short little tubes that you can't see from far off. They're present, but you can't see them.

[Kathy in Alaska]

Thank you very much. I figure the only way to find out the answers to some long standing questions is to ask. Your explanation was perfect for me to understand. Thank you again. Welcome to the Canteen. Hope you stop in again.