Help with Military Fast-Plane Question

[TromboneAl]

One small glitch: The Washington DC area is almost exclusively "Class B" airspace (serving Baltimore-Washington, Reagan Intl, and Washington-Dulles), so Salty would only be in his airplane there if he was in contact with air traffic controllers and if his biplane were equipped with a transponder.

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OK, I'll put those things on his plane, thanks.

 

[Rustic23]

Radios, Civilian AC use VHF while Military use UHF. They don't talk to each other. I never flew transports, but I would guess that the C series aircraft have both. I don't have a clue if civilian AC have UHF. I never flew a fighter with VHF.

 

[samclem]

I don't have a clue if civilian AC have UHF.

Small ones don't, comms are only on VHF. I don't think airliners have much use for regular UHF, but I think their SATCOM systems might operate in that band (though maybe set up just for SATCOM, not for line-of-sight terrestrial comms).

 

[GalaxyBoy]

By the time a museum SR-71 is made air-worthy the pony express would have made it cross-country, so I don't think that's very plausible.

 

[samclem]

ICBM: 20 minutes coast to coast. Launch a "just happened to be waiting for a test" missile from Vandenberg AFB, CA to splash down in the Potomac. The arrival should get the attention of the locals, I haven't worked through how they find the note in a bottle inside the caramelized, smashed, and buried RV.

Normally, this might get the Russians all bothered, but if the satellites are knocked out, how are they gonna know about it? That in itself raises an interesting possible story element: with launch detection knocked out and no way to communicate between national leaders, the two scorpions in a bottle become very dangerous to each other--and everyone else. I'd expect there would be some sort of limited airborne alert of some elements of the nuclear force (tankers and bombers) to prevent having everything caught on the ground in an attack. This is something we haven't done in many decades: it is expensive, hard to do (esp with all the other turmoil that would be going on), and it depends on the comms working (but, unlike the movies, comms failure would not result in a "go to war" scenario).

 

[TromboneAl]

The way I've set it up is that the space plane was just about to be launched on a long-range test flight to Pensacola. It was literally minutes away from a take-off when the EMP happened.

I want the plane to make a "big entrance," since part of the reason for the flight is to let the president know that only a part of the U.S. has been affected.

Ideally, I would like the plane to make a low altitude flyby over the White House, but of course the pilot can' be sure that they have no functional anti-aircraft toys. He can't radio ahead, remember.

So, the idea is that he will fly over Ronald Reagan airport, then turn and come in for a landing.

I'm picturing something I saw at a Blue Angels exhibition. They had one of the planes fly very low and fast. It was dramatic in that you didn't hear the plane until the last second, and it was very loud.

I'm also picturing, from that same air show, a stealth bomber which flew over the crowd, then went almost straight up, turned, and came back over the crowd along the same path.

So, here's my question: How fast could he reasonably fly at a low altitude? Just under the speed of sound to avoid a sonic boom or even slower?

 

[clifp]

I must say I thought I knew something about aviation and EMP, but compared to you all I realize I know very little. A fun thread looking forward to the book Al.

 

[soupcxan]

Option 1: Send a supersonic cruise missile. Mach 3 so LA to DC in an hour. Replace the warhead with a hardened case that can hold a message. Crash it someplace where it's obvious to be picked up (the capital building, some military base, etc.).

Option 2: Submerged subs aren't affected by EMP. After the blast they could surface and use some sort of very low frequency radio communications.

 

[Rustic23]

Why would you want to avoid the sonic boom? The size of the boom, if I remember, is governed by the weight of the A/C, the speed of the A/C and it's altitude. In 1968, we had a fire power demo out on the ranges north of Las Vegas. We brought three aircraft over supersonic, well that was the plan, an F-4, F-105, and an F-111. All were suppose to be at 500 ft agl. The F-4 was at about Mach 1.1, loud boom, the F-105 about mach 1.2, a bit louder. The F-111 was almost twice as heavy and came through about Mach 1.3 or a little faster, the boom blew out all the windows in the tower, the building and all the busses that transported people out. That was the practice. The actual show the F-111 was restricted to sub-sonic. OOOPs

Point is I think you could use the sonic boom an attention getter, with little or no damage on the ground.

 

[samclem]

Option 1: Send a supersonic cruise missile. Mach 3 so LA to DC in an hour.

There are "supersonic cruise missiles", but they have ranges much too short for this--less than 200 miles, in general. High speeds while in the atmosphere just burn a lot of fuel.

 

[kombat]

Does a sonic boom occur the entire time the aircraft is flying supersonic, or just at the point where they accelerate past the speed of sound?

My understanding was you only get the boom when the aircraft passes into supersonic speed, because as they're coming up on the sound barrier, the waves are building up at the tip of the nose, such that as that wave expands outward, anything it passes experiences a big "wave" of all the built-up sound. But once the aircraft is flying faster than sound, wouldn't the sound waves simply go back to being normal waves? They'd be "tripping" over each other, but they wouldn't be amplifying each other harmonically anymore, causing a sonic boom, would they?

 

[Lucantes]

It is my understanding that the "sonic boom" occurs continually, but it of course moves along with the flightpath of the aircraft (it travels along with the plane so you normally only hear it once as it passes near you, putting you in what they call the "boom carpet").
IIRC?

 

[TromboneAl]

I want to avoid a sonic boom because I don't want windows to break. So maybe just under the speed of sound?

 

[Rustic23]

It occurs continually, and, different parts of the aircraft can generate a sonic boom before the entire ac 'breaks the sound barrier'. Al, windows will not necessarily break depending on altitude, size and speed. Another incident, an F-105 on a fly-by at the AF Academy below the speed of sound, that's his story and he's sticking to it, broke windows in the chapel. As I said, the F-4, at about 40,000 lbs, did not break any windows. However, it was an attention getter. Neither did the 105 at about 45,000 lbs. The 111, at about 65,000 lbs did the job quite nicely.

 

[Koolau]

Does a sonic boom occur the entire time the aircraft is flying supersonic, or just at the point where they accelerate past the speed of sound?

My understanding was you only get the boom when the aircraft passes into supersonic speed, because as they're coming up on the sound barrier, the waves are building up at the tip of the nose, such that as that wave expands outward, anything it passes experiences a big "wave" of all the built-up sound. But once the aircraft is flying faster than sound, wouldn't the sound waves simply go back to being normal waves? They'd be "tripping" over each other, but they wouldn't be amplifying each other harmonically anymore, causing a sonic boom, would they?

To "picture" a sonic boom (but in two dimensions) sit by a fairly calm lake front and watch a power boat go by. When its wake hits the shore, that is your equivalent of a "sonic boom" (but a different fluid - water instead of air). Naturally, the point where the wake hits the shore "moves". Same with a sonic boom. There is one continuous "boom" but perceived only where it strikes.

Most sonic booms I recall from years ago had "multiple" components (sort of a ba-Boom!) effect. I assume this was due to the multiple areas of the aircraft creating separate shock waves.

I recall a boom as I was walking in an outside shopping center. There was a long building with a row of shops which each had large plate-glass windows. I could actually see each window react in succession as the "boom" (shock wave) propagated along the length of the shops. None of the windows broke, of course, but each one in succession could be seen to deform and rebound. As a kid of maybe 13 or so, I suddenly realized what a sonic boom was - in a 13 year-old kid's perspective, anyway. YMMV

 

[TromboneAl]

Here's another question: considering an advanced fighter like an F15. The plane carries no ordnance. Would there be anywhere that you could stow a folding bicycle or a small electric bike? For example, in a bomb bay??

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[Rustic23]

Not real familiar with the F-15, but they do have a travel pod.

Not sure you could get a bike or scooter in there. The F-111, still active in the Australian AF does have a weapons bay big enough, and it also has the range and speed you might be looking for. The could be deployed to Red Flag and thats why they are in country.

 

[TromboneAl]

Okay, thanks.

Next question: If all satellites and ground stations are out, and the plane is traveling from Edwards Air Force Base to Washington, DC, when might it lose radio contact with Edwards?

 

[ls99]

It occurs continually, and, different parts of the aircraft can generate a sonic boom before the entire ac 'breaks the sound barrier'. Al, windows will not necessarily break depending on altitude, size and speed. Another incident, an F-105 on a fly-by at the AF Academy below the speed of sound, that's his story and he's sticking to it, broke windows in the chapel. As I said, the F-4, at about 40,000 lbs, did not break any windows. However, it was an attention getter. Neither did the 105 at about 45,000 lbs. The 111, at about 65,000 lbs did the job quite nicely.

Air Force proof once again, you can make a barn fly if you hang a big enough engine on it. Admittedly thes barns, and the C5 are pretty awesome barns.

 

[Rustic23]

It would depend on the radio and the altitude of the aircraft. I would say at least a couple hundred miles. If the A/C has an HF radio, then the range is unlimited, but not always depending on atmospheric conditions. I have listened to the states in Vietnam on HF. However, I know of no fighter that has HF. Another plug for the f-111 is it has the range to go from Edwards to DC without refueling. We flew from Shaw AFB, SC to Mountain Home Idaho and had about an hour and a half of fuel left, and that was against the wind. You should expect a tail wind going east.

 

[samclem]

Next question: If all satellites and ground stations are out, and the plane is traveling from Edwards Air Force Base to Washington, DC, when might it lose radio contact with Edwards?

UHF and VHF radios are all limited by line-of-sight considerations. If we assume a "cue-ball" earth 4/3's earth model (no mountains, but a little "flatter" than the real earth to account for a little bit of diffraction and surface effects), then the formula is:

R = 1.23(√ (Height of the transmitter above the surface) + √ (Height of the receiver above the surface))

Where R= The communications horizon (in nautical miles)
and heights are measured in feet.

So, if plane is at 50,000 feet and the transmitting antenna at Edwards is a 100 foot mast, then the communications should fade out at approximately

1.23 ((10)+(224)) = 290 NM (or 330 statute miles).

Mountain ranges that stick up higher than the assumed earth curvature would decrease the range somewhat. Another aircraft up in the air serving as a relay (effectively, another 50,000 foot antenna mast) could extend the line-of-sight a lot, so that the range would then probably be limited by the power and sensitivity of the transmitter/receiver respectively, not by the line-of-sight issues.

 

[Rustic23]

While most modern fighters are capable of flying at 50,000 ft, most don't, and few would.cruise at that. Above 50 you are required to have a partial pressure suit, and I don't think pilots are fitted for them other than maybe U2 or SR71. Example, once more the 111, we flew most cross countries around 25,000 ft. Because of the wing sweep that is where it was most economical.


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[samclem]

While most modern fighters are capable of flying at 50,000 ft, most don't, and few would.cruise at that.

Right, I was using 50K' as a wag for an altitude to which you might climb for a brief radio chat before resuming cruise.
I know turbo>jet< engines get more economical at high altitudes, but I'm less certain about the "MPG" issue for modern turbo>fans<.

 

[growing_older]

Don't want to mess up your creative process here, but if the massive EMP takes out all the radios, won't it also take out all the modern avionics. Some older planes used hydraulics and less electronics, but even they had wiring harnesses. Wouldn't the planes fall out of the sky with no control systems and no cockpit instruments?

 

[MooreBonds]

Don't want to mess up your creative process here, but if the massive EMP takes out all the radios, won't it also take out all the modern avionics. Some older planes used hydraulics and less electronics, but even they had wiring harnesses. Wouldn't the planes fall out of the sky with no control systems and no cockpit instruments?

T-Al previously mentioned something about California/parts of the West coast not getting hit by the EMP.

However....even if the West coast was hit, there are two sources of 'ultra shielded' hangars:

NORAD - deep in the bowels under the mountain, the military had a handful of planes hidden 'just in case' of a nuclear strike that took out most of the fleet.

Area 51 - they have to keep those [-]reworked UFOs[/-] planes hidden within secret chambers deep underground to keep those top secret prototypes a secret.