One for the Boffins , Professor Newton e.t.c. .

[Scientifiction .]

ACCORDING to wiki & suchlike ( so dont blame me !  ) the mumbo jumbo jet carrys 36.000 gallons ( U S ) of fuel , and produces 2 1/2 Tons Thrust at Cruise .

Now according to Mr Newton , all that ENERGY goes somewhere . Obviously not in our lounge room . so What Happens to IT . What is the result . Say for One minute ?
like a horsepower ( Lifts things for a minute  ' Y ' foot  = ' X '  old nag power .

[Brett Buck]

ACCORDING to wiki & suchlike ( so dont blame me !  ) the mumbo jumbo jet carrys 36.000 gallons ( U S ) of fuel , and produces 2 1/2 Tons Thrust at Cruise .

Now according to Mr Newton , all that ENERGY goes somewhere . Obviously not in our lounge room . so What Happens to IT . What is the result . Say for One minute ?
like a horsepower ( Lifts things for a minute  ' Y ' foot  = ' X '  old nag power .

   The power is the thrust x the speed. Assume some speed, (say, 700 feet/second) and 5000 lbs of thrust, that's about 3.5 million ft-lb/sec, or 6300 HP. It goes into heating up the air, both from the drag churning it up and pulling it along with the airplane, and the heat of the exhaust.

       Brett

[Dave Hull]

I don't have an estimate, but you are also spending a small fraction of that chemical energy to drag an acoustic wave along with you. It doesn't seem like much if you are on the ground and the airliner goes overtop at 35,000 feet, but with that geometry, the energy has spread out over a huge area. Much more impressive is to stand off the end of the runway when something big goes just over the top of you. And you really don't want to stand there if a military jet--particularly with an old, non-bypass engine--goes by.

[Scientifiction .]

And you really don't want to stand there if a military jet--particularly with an old, non-bypass engine--goes by.

Why would that be ?

[Ken Culbertson]

Why would that be ?

That is an Aardvark with a bad case of indigestion.

Ken

[Brett Buck]

I don't have an estimate, but you are also spending a small fraction of that chemical energy to drag an acoustic wave along with you.

   That's just more churning up the air, just at a relatively high frequency.

     Brett

[Trostle]

I don't have an estimate, but you are also spending a small fraction of that chemical energy to drag an acoustic wave along with you.

I do not remember the numbers, but when I was in school, I had a professor calculate the increased thrust of a booster rocket if the sound it created could be converted to additional trust.  It was not a large number like anything more than 1% but it was still significant, like it would more than offset the weight of the paint on the booster.  (If I took notes then, they are long gone.)

Keith

[john e. holliday]

Don't let the powers in control see this.  They will want to shut the jets down for heating the atmosphere as well as polluting it

[Dave Hull]

Don't worry Doc. Those same folks spend a lot of time on jets going back and forth. If they had to go by train (likely the most efficient way, other than by bicycle) they would realize very quickly that maybe we should allow air transport to continue as long as the engineers keep incrementally improving efficiency....

[phil c]

Why would that be ?

Great Picture.

When I was in grade school our Dad took us out to Woldchamberlain Field(not sure, it was a loooong time ago.)  Virtually any one could walk in.   There was an area up on the roof for Plane Watchers.
We went right up to watch. It was pretty impressive, that's for sure.  A military fighter jet came out of the hanger and headed down to the end of the runway.  It was a VooDoo(forget the number)  I didn't know all the specs but I had learned it could fly supersonic.  It went out of sight about half a mile away, behind some hangars.  It rumbled there for about 5 minutes and then we heard an explosion.  It took a few seconds for the plane to roll out from the hangars, roaring like I was standing next to the track when 3 diesel locomotives were pulling a 100 car consist.

Right in front of us it really exploded, just as it was going behind more hangars.  Did it blow up??  3-4 seconds it came out from behind the last hangar about roof high  going fast.  It got louder for a bit as it climbed up faster and faster until it vanished.  It was still louder than than any plane I'd heard before.

Woopee!  That really made my Day!

Teaching Kids-  many years later we went to see a Blue Angels airshow at the Harrisburg Airport about 1975.  The three kids and wife came.  The Blue Angels were flying the fairly early twin engine Hornets .  Along with 4-5 other demos there was a short break  The Angels came right from behind us, may 150 feet and making a ton of noise. They did a very exciting show and then disappeared for 3-4 minutes.  Suddenly four planes exploded from behind us.  We were about 200 feet from the side of the runway.  The planes did the "Flower" ( I think it's called)  about five hundred feet away over the river.

The kids were really excited by every turn around.  One plane came our way after several other maneuvers- right over out heads.  He did it twice, no more than 100ft banked way over.  Tf One time the pilot lifted his face shield, waved briefly, flipped it up and flew over no about 100 ft.  The engine noise wasn't deafening.  He must have cut the turbines back a bit so as to no blow anyone's eardrums.

Wonderful Demo!

Phil C
12/17/2012



Phil Cartier

[Steve Helmick]

When I was in 5th grade, the Thunderbirds were doing a demo at Maxwell AFB...straight wing F-84's IIRC, when one crashed, and I think the pilot was killed. I'd guess it was a flame-out. I've seen some air shows, I think the last one was at Edwards AFB in '61. They had an F-104 Starfighter doing a minimum radius 360 turn...which was pretty much out of sight.

The absolute BEST airshow I ever saw was at the NW Regionals at Sand Point NAS in Seattle, 1963 or 1964. Mira Slovak taxied past the grandstands in the Bardahl P-51 racer. A whiff of the exhaust told us it wasn't just avgas. He taxied down the ramp and took off without any drama. Maybe 10-15 minutes later, he made a low high speed pass down the runway at probably 450 knots, WFO. Such a glorious sound from that Merlin!  Steve