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I would think that having a huge mass spinning around should produce massive gyroscopic forces when turning or pitching.
There must be some clever way of minimising or eliminating the effects... How is it done?

(An example of the sort of thing I am talking about)
AWACS

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  • $\begingroup$ It certainly doesn't affect it a great deal - it's not much bigger than the engine pods, for a start.... and spins very slowly. That conspiracy theory shows a pathetic lack of knowledge, for something presented as authoritative (ignoring the caps lock and atrocious spelling) $\endgroup$ – Jon Story Nov 25 '14 at 9:48
  • $\begingroup$ Id think the aerodynamic forces of the radar dish would be much more of a factor than the rotation, which is pretty slow. $\endgroup$ – GdD Nov 25 '14 at 14:00
  • $\begingroup$ The current trend in AWACS design relies on AESA phased arrays anyways... $\endgroup$ – Deer Hunter Nov 29 '14 at 4:10
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The AWACS surveillance radar components consist of multiple units grouped in 3 locations. Only the antenna array and its electronics are in the rotodome.

The receivers, radar processors, and radar control & maintenance panel are in the main cabin.

While fiberglass and rubber make up the outside coating of the dome the inside is mostly hollow except for the antenna rays.

AWACS aircraft produce greater drag relative to that of civilian jet liners. Therefore, engines for AWACS require non recurring engineering(NRE) to handle the dual generator requirements of the aircraft.

In order to reduce its air drag during take-offs, and while flying endurance speed the dome is tilted down 6° at the front. The rotodome itself is hydraulically rotated. Remember, the Boeing 707/320 from which the Boeing E-3 Sentry was derived can very easily carry a huge cargo load . Therefore, the addition of a 1.5- 2 ton rotodome makes no difference to an AWAC which in any case is not carrying more than 20 – 30 crew members.

Generally the radome scans at 6 revolutions a minute. When the radar is not operating the radome rotation rate is set at 1 revolution every four minutes ( In case of the E-3 it is 1 rotation every 10 seconds). Ergo, the torque that the rotodome produce is very low.

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On the E2 Hawkeye the dish does not rotate very fast (ie, very slowly), and so the torque is probably negligible. Usually the radomes are designed to help generate lift, and while certainly not as effective as a wing, do offset their own weight quite a bit.

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    $\begingroup$ Just an addition to this: It's not only about mechanical torque - the slow speed also prevents excessive aerodynamic forces from the spinning disk (ie one side of the disk generating more lift than the other) $\endgroup$ – Jon Story Nov 25 '14 at 9:44
  • $\begingroup$ @JonStory Do any AWACS aircraft have any moving parts exposed? I thought the rotating antenna was entirely contained within the radome, which is stationary with respect to the airframe. So there wouldn't be any aerodynamic forces resulting from the rotation. $\endgroup$ – pericynthion Nov 25 '14 at 19:25
  • $\begingroup$ youtu.be/stof3n7vVPc this video shows it clearly rotates. $\endgroup$ – vasin1987 Nov 25 '14 at 19:40
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    $\begingroup$ The radome definitely rotates on the E-3, I'm not sure about others youtu.be/2tlHDpfIYWo?t=4m37s $\endgroup$ – Jon Story Nov 25 '14 at 19:40
  • $\begingroup$ @JonStory: According to Wikipedia, at least, the E-2 also has a rotating dome. But I'm curious about your comment about asymmetric lift from the dome. I would have thought it would behave more like a round wing rather than a helicopter rotor. I could see some Magnus effect, perhaps. Can you expound? $\endgroup$ – Fred Larson Nov 26 '14 at 17:51

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