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Fake sonic booms

The students could probably measure the speed of the shuttle by measuring the sonic booms using cell phones at several locations.

But then, maybe the government is faking the speed of sound too.
 
R.Mackey said:
In contrast, I've been up at Edwards for a few dozen supersonic flights, from quals on F/A-18s to testing the F-15S, and F-22 trials. Those are more like rifle shots. Not remotely comparable.
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Concur. I went to "C" and "A" school down at Corry Station, close enough to watch the Blue Angels practicing every day over Pensacola. They never boomed low enough to be too terrifying.

Later on, I was stationed at Norfolk. Used to visit the Oceana commissary right at the tail end of the EA-6B's career. That sucker would shake the roof of the place...not from sonic booms - the bastard was just that loud.
 
Dan O. said:
The students could probably measure the speed of the shuttle by measuring the sonic booms using cell phones at several locations.

But then, maybe the government is faking the speed of sound too.
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Sure can. My father also used to host school experiments where they'd talk to the Shuttle (and Mir) via 2-meter Ham radio, both voice and packet. In order to get a good signal, they needed a directional antenna, and hence the exercise. They'd work out the orbits, and during the passes a team of students would steer the antenna accordingly. Worked like a charm.

JoeyDonuts said:
Concur. I went to "C" and "A" school down at Corry Station, close enough to watch the Blue Angels practicing every day over Pensacola. They never boomed low enough to be too terrifying.

Later on, I was stationed at Norfolk. Used to visit the Oceana commissary right at the tail end of the EA-6B's career. That sucker would shake the roof of the place...not from sonic booms - the bastard was just that loud.
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Yup, turbojets are noisy beasts. I've always thought the (similarly subsonic) Harrier was a noisy bird, but the Intruder/Prowler might be even worse...
 
R.Mackey said:
Sure can. My father also used to host school experiments where they'd talk to the Shuttle (and Mir) via 2-meter Ham radio, both voice and packet. In order to get a good signal, they needed a directional antenna, and hence the exercise. They'd work out the orbits, and during the passes a team of students would steer the antenna accordingly. Worked like a charm.
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Cool! How much dwell time did each pass have? (I can't imagine they could have reliably tracked along the orbit with the directional antenna. ETA - By this I mean constantly adjusting the Azimuth/Elevation to match the path of the shuttle real-time) From my old SATVUL exercises, I'm guessing around 5-10 minutes overhead time? (Depending on your sensitivity/ERP/beamwidth/etc...)
 
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Yup, not long. Low orbit. We'd get six minutes of solid comm on average. I think we once managed 11 minutes on Mir, when it was directly overhead, at home with the big antenna, at altitude, and with the ocean only a few miles away... The cosmonauts seemed to have a lot of time on their hands, and we talked to them fairly often.

But we did track the orbit as it went over. We'd paint lines on the ground and set up little flags, one for every minute, and just march along as close as we could. Worked quite well.
 
R.Mackey said:
But we did track the orbit as it went over. We'd paint lines on the ground and set up little flags, one for every minute, and just march along as close as we could. Worked quite well.
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Well, I'll be damned. Hats off. Who needs synchros, right? :D

Besides, it's not like you're pointing a target illuminator. From what I understand of the 144.000 MHz range, you don't really need to be dead on with a directional antenna. Periodic adjustments every so often to keep it in the ballpark, and it looks like that's just what you guys did.

Man - why couldn't I have had cool experiments like that when I was coming up? All I learned about was a bunch of Young Earth Creationism and how to refute evolutionists.
 
Right. Plus or minus about five degrees is plenty. It isn't like S-band or Ka-band comm where you're focusing through a straw. 2 meter is pretty forgiving, but it is only line-of-sight.

If I remember the apparatus correctly, he had the antenna on a boom made from 2x4's, with the lines on the ground for azimuth, and a plumb bob and a big paper protractor for elevation. Redneck engineering at its finest.

He still has some QSL cards from Mir. I'd have to ask him which ones.
 
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Shadetree HAM engineers never cease to amaze me. I've seen some pretty entertaining (and impressive) rigs. Getting my amateur class license has been on my to-do list for a long time now. Maybe after I get my black belt in Judo, run a triathlon, finish my degree, land a better paying job, etc... :D
 
I haven't thought about this in years, but it's coming back to me...

Talking to the Shuttle was quite popular. We got a lot of contacts on Mir because, first of all, they were on orbit for a long, long time, and second, not too many people seemed to know about it.

Shuttle was different. Lots of competition. We could get a weak signal with no direction-finding at all, but if we wanted them to talk to us in the limited time available, we needed to have a nice, strong, readable signal, and we needed to get on it as soon as the track began. Being on the West Coast helped, but we had to be right on it as soon as they came over the horizon.

Although I also seem to recall my dad had an ace in the hole -- 2 meter simplex is supposed to be limited to 5 watts, if I remember right, but he had a 1500 W amplifier on standby, just in case it didn't work out, so as not to disappoint the kiddies. Never needed it, though. :p
 
Nerds!


To the OP, I vote for the mess-with-the-teacher's-head option. Tell your niece to tell the teacher that the sounds aren't faked, but that the so-called space shuttle is simply a cover story for the real cause of the sonic booms. The US government is trying to repair a rift in the space-time continuum, sometimes known as the "San Andreas Fault". This repair work involves the demolition of the older, failed repair, also know as the "Los Angeles Rams", and the second boom is the echo off of the area's cell phone towers. Which everyone knows are really mind-control ray emitters. So you only think you hear the second boom.
 
R.Mackey said:
Serious answer, it would be extremely difficult.

The Shuttle gives off a unique double boom, caused by its rather blunt structure and high speed. The shockwave is known as an oblique shock, and it always starts at the nose of an aircraft, and the shock front takes a conical shape, where the air inside is moving with the aircraft, the air outside moving at ambient speed -- the shock front itself is the discontinuity, and the air moves at totally different speeds on either side. That's what a shock is.

Now, the conical front has an angle determined by the speed. This angle takes some work to compute, but generally speaking, the faster the aircraft is moving, the narrower the cone. This is important for design, because you don't want any of the aircraft to lie outside this cone. If it does, it greatly increases the drag and the load on the structure. This is why the faster an airplane gets, the more swept back and narrower its wings, until you have things like the SR-71 that resembles an arrowhead more than a typical planform.

The Shuttle, however, doesn't really care about drag so much because it spends most of its performance outside the atmosphere entirely. As it descends, starting from extremely high speed, a good chunk of structure does in fact lie outside the oblique shock coming off the nose, and this sets up a second shock wave, approximately 30 meters behind the first one. This distance translates to a time delay on the ground, and thus a double shock is clearly audible, occuring about 0.08 seconds apart (or more, depending on temperature at altitude).

Modern fighter aircraft, on the other hand, only produce single shocks -- any additional shocks thrown off by structure are weaker, lying within the primary cone, and will be closer together to the point that they will combine with the main shock at any appreciable distance from the aircraft. To get a double boom, you would have to fly a pair of them in close formation, which could be done, I suppose. However, this would be easily detectable by observers with binoculars, and it would have to fly directly over heavily populated areas (the Los Angeles basin, and Orlando Florida, respectively). Good luck with that.

There is also the magnitude of the boom to consider. The Shuttle dives quite steeply at extreme speed and thus makes a particularly loud boom. This is quite different from the boom from fighters -- much more of a rumbling, earthquake-like shock than the simple *SNAP of a lighter aircraft, one that is trying to avoid drag and compressing the air much less.

So, in closing, to replicate the double boom, you'd need a different vehicle or series of vehicles with similar performance. I never got to hear the XB-70 Valkyrie at full tilt, nor does the Concorde or SR-71 fly any longer, so I can't imagine what that might be. This mystery vehicle would also have to look like the Shuttle, and follow its same route. In short, if it cracks like a duck, it probably is one.
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To fake the STS would be very difficult. Dynamite on a Rocket?
It is my understanding that the shock comes off the front and back of the airplane--every one I've ever heard was a double boom--and I spent 4 years at Edwards doing flight test.
Just FYI, Ryan, et al. The SR-71 sonic boom is a (Fairly) long, drawn-out thing, and not of a particularly high amplitude.
When I was at Edwards in the 1970's we flew the YF-12/SR aircraft with F-104 chase (only for T-O, landing, and refuel, of course). The SR-71 bOOm was a kaaaaa-boooooom.
The F-104 was a very sharp, rifle-like CRACK-crack! of a very, very short duration--and BTW-I've actually SEEN the shocks from a 104 on the lakebed!
The Flight Sciences guys told me that that was due to the fact the aerodynamic length of the SR is around 1000 feet, and the F-104 is more like 10 feet. Not being a fluids guy, I dunno.
 
Dan O. said:
The students could probably measure the speed of the shuttle by measuring the sonic booms using cell phones at several locations.

But then, maybe the government is faking the speed of sound too.
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The last time the shuttle landed, here in California, I was in the chatroom and it was about three minutes between the time I heard the booms and someone else in chat living in Los Angeles heard the booms.
 
I wonder if this is how most California teachers are?
My niece had a teacher a few years ago who told her that the human body was not designed to sit in chairs.
He had removed all the chairs in the classroom and they kinda hunkered down on the floor.
My niece really believed this and for about a year would not sit in chairs.
 
Brattus said:
I wonder if this is how most California teachers are?
My niece had a teacher a few years ago who told her that the human body was not designed to sit in chairs.
He had removed all the chairs in the classroom and they kinda hunkered down on the floor.
My niece really believed this and for about a year would not sit in chairs.
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Nah...every place has bad teachers and the bad ones are the ones that get bitched about publicly. I think the biggest problem is the teacher's union, which makes it difficult to get rid of bad teachers. There used to be a kindergarten teacher at the school where I work and it took years to get rid of her, even though she was physically abusive to the children.
 
Everybody knows Neil Armstrong walked on the film studio in 1969. That was how he and his friends resisted the solar radiation beyond the Van Allen Belt.

Simple, right ?
 
Lisa Simpson said:
Nah...every place has bad teachers and the bad ones are the ones that get bitched about publicly. I think the biggest problem is the teacher's union, which makes it difficult to get rid of bad teachers. There used to be a kindergarten teacher at the school where I work and it took years to get rid of her, even though she was physically abusive to the children.
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Wow! Abusive! I'm not sure which is worse. Filling their young minds with garbage they carry around forever or slapping them around.
I of course think both are horrible and unacceptable but the sting of a slap will eventually fade away.
 
Especially said:
Everybody knows Neil Armstrong walked on the film studio in 1969. That was how he and his friends resisted the solar radiation beyond the Van Allen Belt.

Simple, right ?
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You mean fellow highly trained astronauts or was Neil having a barbecue up there?
 
Forgive my nieve question:

But can the sonic boom harm the Earth's ozone layer? It currently has a hole.
 
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