Forum: General F-35 Forum

velocityvector wrote:

A mass cannot travel faster than the speed of light in any applicable reference frame. Not even given the latest hypothecations. Current test results are well within acceptable margins for error. Prove me wrong, with proofs I dare you ;>)

I am not a physicist, so I cannot prove you wrong. I can only read about some recent experiments that were reproducible so it seems. I imagine that the scientific community will debate the findings for years, much like the root causes of climate change. Perhaps you can participate.

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johnwill wrote:

guardbaby wrote:

LOS is as simple as 123.... well, 12.3 that is. Take your height above sea level, take the square root of this height and then multiply that by 12.3. This gives you an approximation of how many miles you can see to the horizon (LOS to the horizon).

For example, an F-35 flying at 40,000 feet; Square root of 40,000 is 200, 200 times 12.3 shows you that it is approximately 2460 LOS miles to the horizon. Now for the ships radar which sits 100 feet off the water; Square root of 100 is 10, 10 times 12.3 shows you that it is approximately 123 LOS miles to the horizon.

It may be simple, but it is also wrong. Try multiplying by 1.23 instead of 12.3. So at 40,000 ft, LOS is 246 miles and at 100 ft it is 12 miles.

Johnwill, thanks for keeping me honest. You are correct in that it is 1.23. I never knew that 50 years would shift a decimal place in your memory. Embarassed

That stuff happens to me every day. We old coots have to look out for each other. I had never heard of your method, so I had to do the cosine tangent thing with earth radius and altitude. Your way is so much easier. Thumb

johnwill wrote:

That stuff happens to me every day. We old coots have to look out for each other. I had never heard of your method, so I had to do the cosine tangent thing with earth radius and altitude. Your way is so much easier. Thumb

Being a former enlisted swine, I try and find the easiest method to accomplish a task.

My little brother and his crew were trying to figure out the distance to horizon while flying a C-17. Not having the actual trig rules on hand they were left scratching their heads, now I have something to tell him. Thanks guys.

I have a question/thought

In the special case of one-on-one, F-35 vs. Stealthy Destroyer. Radars form an "arc" that is cut off/blocked by objects, such as the earth, thus LOS. If the F-35 were on the deck and over the horizon, so that the ship radar is above the F-35, could the F-35's sensors detect the ship radar signal above it and use that information to locate the ship, while the horizon is still in the way. Thus enabling an OTH shot?

Just a thought/question as I am not familiar with radar detector capabilities other than those you can buy for your car.

Sufa Viper.

I would imagine the F-35 would have to intercept the signal to register it. If it can't intercept the signal then it won't be able to triangulate its position.

That engagement would likely involve a higher F-35 flying farther away passing targeting data to the low-flying F-35.

By intercept do you mean rise up into the "radar beam"? I guess my question is: is there technology that would allow the detection of a "radar beam" (I know not the best termonology) without actually being in it. Theoretically it is possible, but I am not sure if the technology is there.

Sufa Viper

Yes that is what I mean by intercept. What you are getting at is OTH (Over the Horizon) radar detection. What that is is that a certain radar set gives off radio waves which bounce off of the ionosphere and then hit the target over the conventional radar horizon. I would imagine an F-35 would easily intercept the radar emissions then. Unfortunately surface vessels don't have such OTH radar antennas (they are too cumbersome to be ship-based) and as stated before they are useless for fire control. As such the only way an F-35 could detect a surface ship's radar (that's non-OTH capable) while being masked by terrain would be if another F-35 was present and could pick up the radar from the ship so that it could pass the data to the low-flying F-35 via MADL.

Regardless of whether or not the F-35 could detect OTH emissions, it's ESM would still be able to detect the ship before the ship detected the F-35, even with a LOS view.

sufaviper wrote:

I have a question/thought

If the F-35 were on the deck and over the horizon, so that the ship radar is above the F-35, could the F-35's sensors detect the ship radar signal above it and use that information to locate the ship, while the horizon is still in the way. Thus enabling an OTH shot?

Sufa Viper.

I'll assume you mean under the radar horizon. In this scenario, the short answer is yes. Depending on the platform and the munition, an ASM could be launched without a precise location. The munition flies a search pattern, and then uses its onboard sensor(s) to find a target.

I'm having difficulty articulating exactly what I mean, so I made a quick painting (read crude) to simplify my description (a picture is worth a thousand words).

Blue = earth (shrunk to emphasize curvature)
Red = Destroyer/target
Black = Surface radar position
Orange = Surface radar beam, wide angle array, note the horizon
Green = F-35 (or other plane, as for this scenario it doesn't require stealth
Yellow = Radar Detector Radar (the technology I am asking about)

In therory the plane could bounce the yellow radar beam off the orange and get a reading (this can be done in a lab, but I'm not sure if the technology exists to pull it off in the real world due to interference). If the plane took a few readings along with some other information it could produce a good estimation of where the orange beam source is.

Anyway I hope that better explains what I was thinking,

Sufa Viper

sufaviper wrote:

I'm having difficulty articulating exactly what I mean, so I made a quick painting (read crude) to simplify my description (a picture is worth a thousand words).

Blue = earth (shrunk to emphasize curvature)
Red = Destroyer/target
Black = Surface radar position
Orange = Surface radar beam, wide angle array, note the horizon
Green = F-35 (or other plane, as for this scenario it doesn't require stealth
Yellow = Radar Detector Radar (the technology I am asking about)

In therory the plane could bounce the yellow radar beam off the orange and get a reading (this can be done in a lab, but I'm not sure if the technology exists to pull it off in the real world due to interference). If the plane took a few readings along with some other information it could produce a good estimation of where the orange beam source is.

Anyway I hope that better explains what I was thinking,

Sufa Viper

ESM could get a bearing and a rough range. If the dictionary was good enough, it might have enough info to time/range the signal. Geo-locating, or getting a good fix would be harder.

wrightwing wrote:

Regardless of whether or not the F-35 could detect OTH emissions, it's ESM would still be able to detect the ship

maus92 wrote:

ESM could get a bearing and a rough range. If the dictionary was good enough, it might have enough info to time/range the signal. Geo-locating, or getting a good fix would be harder.

What is ESM? You seem to be talking about a sensor, which presumably means it has to be capturing & reading electromagnetic radiation of some frequency, like radar captures & reads radio-frequency energy and the electro-optical system captures & reads visible-light-frequency energy. Other than those two and infra-red, what other frequency range can a plane to use?

sufaviper wrote:

In therory the plane could bounce the yellow radar beam off the orange and get a reading (this can be done in a lab, but I'm not sure if the technology exists to pull it off in the real world due to interference).

A lab experiment has gotten photons to bounce off of other photons? I want to read that experiment report.

Or perhaps you were talking about detecting the air's interaction with the original radar beam... the visual equivalent would be having one person see another's flashlight in the dark even if there's a wall directly between the people, but that's not bouncing light off of light; it's passive sensing of light that bounced off of something else in the environment, even if just some particles in the air. Perhaps this can be done with radar, since there are weather radars which depend on the air (or suspended particles in it) to bounce at least some of that energy back, but it would be passive for the one that's watching for it. And then getting away with turning on your radar would depend not on how stealthy your vehicle's body is or how powerful or which band the radar shining on you is, but on how LPO your own radar is.

maus92 wrote:

Depending on the platform and the munition, an ASM could be launched without a precise location. The munition flies a search pattern, and then uses its on board sensor(s) to find a target.

That only helps if you know there's a target somewhere out there to find, or don't mind wasting missiles by using them merely as probes that get launched to search for something that turns out not to be there. The former gives no inherent advantage to either the ship or the plane, because our hypothetical scenario has to start by positing which one does or doesn't know that the other is somewhere around in the first place. The latter would be slightly less ridiculous for the ship because it can carry more missiles and thus can afford to lose/waste more, and because a single hit would probably be enough to destroy the plane.

Forum: General F-35 Forum

F-35 and stealth destroyers?