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Andy_P
Pocket GPS Moderator
Joined: Jun 04, 2005
Posts: 19991
Location: West and Southwest London
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 Posted: Sat Apr 16, 2011 3:56 pm Post subject: |
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So how does it cope with "Turn around when possible..."  |
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Chris32
Occasional Visitor
Joined: Jan 03, 2006
Posts: 38
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| Posted: Sat Apr 16, 2011 4:50 pm Post subject: |
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| M8TJT wrote: | Ah, I see it all now  Simplistically, the control surface on the front provides (say) lift and the fins at the back hold the back down causing a rotation force through the centre of mass thus changing the trajectory. I still have a problem understandin how a ships rudder works though  |
A difference between a ship and a mortar bomb is that the ship has continuous propulsion which acts through the axis of the vessel. So, putting over the rudder causes rotation of the vessel about its own centre of mass and the propeller pushes it forward along the new directional axis. There are of course all sorts of other ways in which ships change direction - vectored propellers or jets - lateral propellers - twin screws driven in opposite directions. Speed boats often have horizontal planes that enable rolling into a turn and using the whole hull as a planing device.
Sailing boats balance various forces - wind on the sails - water pressure on the hull, keel and rudder to maintain the desired course. |
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Chris32
Occasional Visitor
Joined: Jan 03, 2006
Posts: 38
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| Posted: Sat Apr 16, 2011 4:58 pm Post subject: |
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| Andy_P wrote: | Thinking back to my gliding days, where you have very simple control surfaces - rudder on the tail and ailerons on the wings.
If you tried to turn using the rudder alone, you pretty much just carried on in the same straight line, just crabbed sideways. |
Thanks Andy - that's a great example of the effect. |
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Duddy
Lifetime Member
Joined: Dec 09, 2006
Posts: 219
Location: Manchester UK
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| Posted: Sat Apr 16, 2011 5:20 pm Post subject: |
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The mortar round does have continious propulsion, after it's reached its apogee, i.e. gravity @ 9.81 m/s/s.
It's this time it is lookin for it's target.
The fins will apply an external force to divert it from it's normal parabolic path
_________________
HUAWEI P30 Pro (new edition) with Speedtrap Alert & alcatel1 for SatNav
CoPilot 10 with CamerAlert
RoadHawk in-car video
Reading glasses getting thicker as is my waist
Retired but want to go back to work for a rest. |
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M8TJT
The Other Tired Old Man
Joined: Apr 04, 2006
Posts: 10118
Location: Bexhill, South Sussex, UK
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| Posted: Sat Apr 16, 2011 5:21 pm Post subject: |
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Thanks again for that Chris, great explanation.  I'll crawl back into my shell now  |
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DennisN
Tired Old Man
Joined: Feb 27, 2006
Posts: 14907
Location: Keynsham
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| Posted: Sat Apr 16, 2011 9:00 pm Post subject: |
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| DennisN wrote: | Wot?  |
_________________
Dennis
If it tastes good - it's fattening.
Two of them are obesiting!! |
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