China has installed the last panel in the world's largest radio telescope

20 תגובות

1. There is a parachute.

   The advantage is a better power/lift ratio than existing models. The Magnus Elek effect.

   I built something similar 25 years ago but it wasn't strong enough and fell apart and I didn't continue. See correspondence with Eli, a professor from Harvard from two years ago:

   —–Original Message––
   From: Israel Shapira
   To: Eli
   Sent: Thu, Jun 19, 2014 7:32 pm
   Subject: Re: flying machine - note the patent date

   On Jun 19, 2014, at 2:48 PM, Eli Tziperman wrote:

   that's your flying machine! amazing... what is the date, I didn't
   see it explicitly mentioned there

   2014-06-19 14:10 GMT+02:00 :

   —–Original Message––
   From: snuz21
   To: zgerony
   Sent: Thu, Jun 19, 2014 5:06 am
   Subject: Flying machine - note the patent date

   From Wikipedia

   http://en.wikipedia.org/wiki/FanWingPatrick Peebles developed the FanWing concept in 1997. He formed the FanWing Company and applied for patents on his idea in several countries where aircraft are manufactured. In July 2005 the company advertised that the first FanWing aircraft was in development in the United Kingdom.

   I visited you with the scale model in Weizmann at about the same time. The larger model has been at my house in the kibbutz since 95

   The problem was always the balance - because of the high rotation speed, the heavy cylinder simply came off the axis and was a danger, so we had to stop

   A similar thing happened to me last week with the experiments with lasers: I checked with a tachometer the angular rotation speed of a rotating disk. We were ready for everything except for one thing: that at an extremely high angular velocity the disk was simply cut in two due to the centrifugal force

   It was quite scary: I was 20 cm away from the puck when suddenly a big boom was heard. I thought the engine had exploded, but what happened was that each half flew to a different side, and one of them just cut through the warehouse door, including its metal plating

   But in the second before the explosion, I managed to see that the disc was spinning at only 8000 rpm, which still leaves a chance that the "trivial experiments" will still yield positive results. Very little chance. I need a speed of 20,000 rpm and even then there is not much hope

   .but someone has to do those experiments, and it might as well be me. Too bad I don't have a normal lab, but that's what there is

2. Israel
   I didn't know! I wouldn't want to fly it myself ….. engine out and you're dead 🙁

3. Miracles

   You've heard of a plane called a Fan Wing

   https://www.youtube.com/watch?v=kgOAwzG9Fd0

4. Israel
   I worked with a similar box - it said 200 nano. We used it to synchronize remote systems.

5. Miracles

   I found it:

   http://www.arbiter.com/catalog/product/model-1088b-gps-satellite-precision-time-clock-40ns.php

   Let's hope they are not too many thieves..

6. Israel
   The time accuracy of the GPS clocks is 10 nanometers. In practice, GPS-based clocks provide an accuracy of 200 nanometers. I read that today there are watches with 40 nanometer accuracy, but I have not worked with such.

7. rival
   The method you suggest exists in several systems. There are two main methods. One compares a relief received from a radar to a relief stored in memory. The second compares images from an optical camera with images stored in memory.

   In principle, the technique is simple - what every pilot learns - "clock, map, terrain": look at the clock, look at what you expect to see now on the map, and now look outside.

8. There was a European-Galileo satellite navigation project I think.. and there is an idea of ​​comparison with other navigation systems and an atomic clock as Nissim mentioned. Today there are only two systems Glasnos (Russian) and GPS (American). In his hand the Chinese and the Europeans are reluctant

9. Miracles

   With what accuracy is the GPS time transmitted?

   Micro, nano, pico..

10. What about navigation by ground route? If the missile (for example) contains in its head the map of the landscape from the place of its launch to the target (the target area in high resolution) can it not navigate independently without the need for GPS?

    (using cameras or radar)

11. Joseph
    Intuition does say three. The problem is that the GPS receiver does not have an accurate clock. If we had an accurate clock - we could directly measure the distance to each satellite, then we would make a cut of three spheres to get a position.
    But - we don't have such a watch, so we have no way to measure distance. With the help of a fourth satellite and a calculation trick, the problem can be solved.

12. Yes. We all agree that in the absence of a satellite system we will need inertial navigation. I tend to accept that in 3 dimensions maybe cutting 4 satellites is necessary even though the mathematical intuition says 3. Regarding correct time accuracy. Beyond that, as I said, accelerometer accuracy is required at a level that may not exist today.

13. Joseph
    You need at least 4 satellites….

    The main problem with inertial navigation is the accuracy of the gauges: both the line gauges and the rotary gauges are not accurate enough to approach the accuracy of GPS. Increasing time measurement accuracy is less important.

    A secondary problem is initializing an inertial navigation system: the system needs to detect the Earth's rotation axis to cancel this rotation during integration.

14. The navigation instructions for military systems besides being more accurate are encrypted with keys (passwords). Today there are encryption methods that will take many years to crack. Nothing is immune because the human factor of the hackers is creative, and the human factor of the defender - information can be taken from it. Semi-quantum encryption and hopping information carrier frequency - they cannot be cracked that easily.

15. A gyroscope and a time synchronization clock can measure instantaneous acceleration in time and calculate the position graph as a function of time. This is called inertial navigation. 30 years ago these were the navigation systems. Today there is GPS with military and civilian resolution, and I don't know if there are gyroscopes. The disadvantage of inertial navigation is the inaccuracy of the time clock and the inaccuracy in measuring acceleration in 3 axes, creating a positional error and this is cumulative. In GPS, the system receives spatial coordinates with a constant and small error, since it is obtained from cutting 3 coordinates from 3 satellites at any given moment. There is a project launched in collaboration with Israeli scientists and Western countries (USA?) as I imagine to create a special chip that measures at least accurate time and possibly accelerations as well. This chip is being developed now, precisely from the understanding of the Western countries after China blew up its satellite in space by a missile, that if China damages their satellites, they will go back technologically to the Stone Age.
    The people will not be destroyed, but all transportation, weapon systems, and more will be disabled. The article here is therefore not delusional. If the radio telescope is used to jam enemy satellites this is what will happen.

16. Joseph
    To disrupt GPS, a device that fits in your pocket and costs a few hundred shekels is enough.
    On the other hand, I don't understand how an atomic clock prevents dependence on satellites. The satellites themselves are not the source of the exact information they provide - but ground stations that transmit to the satellites.
    In principle - you can navigate directly from ground stations, but then the range of coverage is very limited. It does not need any local atomic clock.

17. In short - the modern network is fragile, and the primitive network of planes with gyroscopes and a control tower - less fragile for this kind of threat. A transmission from a control tower can be encrypted in a way that makes it difficult to decipher. Not something simple with a password, because the Chinese hackers can easily open that. Semi-quantum encryption (no quantum encryption yet), with hopping transmission frequency - seems more in the direction.

18. If the intention is to disrupt military and civilian satellites in the conflict, this is a source of concern. If this happens unequivocally, it will be necessary to destroy the site, because all navigation of weapons, all satellite intelligence, the entire civil flight system and even WAZE are built on GPS. To be honest, the world is already preparing for this by developing an atomic clock chip that will allow accurate inertial navigation whose cumulative error from the moment of departure from a certain point to the goal, will be accurate enough to avoid the need for GPS. In my opinion, this will not be enough and it will be necessary to return to the gyroscopes of the 80s as the main system.

19. To listen to an astronaut on the moon, or even a skid around Jupiter or Saturn, you don't need this kind of monster. A fairly modest radio telescope is enough.

20. This could be a tremendous antenna for communicating with tyconauts (spacemen in Chinese) that will be sent to the moon/mars, or for receiving signals from probes that will be sent to places in the solar system. So it's not completely a waste. After all, radio telescopes haven't discovered anything dramatic for a long time

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