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"The location of the undercarriage and the height from the ground of the aircraft’s centre of gravity have a very important role in the design of aircraft. In the case of a “tricycle undercarriage” the main wheels are situated at such a distance behind the centre of gravity that its projection at take-off and landing angles of attack (plus a safety margin of 2-3 degrees do not fall outside the line joining the right and left supports. This prevents the aircraft from nosing over and provides stability during the landing run." __Page 13,Theory of Flight

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It can be easily understood that in a Tricycle configuration, if CG(or its projection) is aft of supporting main wheels, Tail Strike can happen. And in Tailwheel configuration, if CG(or its projection) is forward of supporting main wheels, then 'Nosing Over' can happen. But the line "In the case of a “tricycle undercarriage” the main wheels are situated at such a distance behind the centre of gravity" and line "This prevents the aircraft from nosing over " is contradicting.

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    $\begingroup$ Tail wheel & tricycle are opposites. Tricycle configuration = has a nosewheel. Which is what's being discussed in the quoted text. Nosewheel, then CG, then main gear. This works to prevent tailstrikes on takeoff & landing. What nosing over is with tailwheels, tail strikes are with nosewheels. The text is correct. $\endgroup$ – Ralph J Jul 21 '20 at 16:38
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    $\begingroup$ In a taildragger the c.g. is aft of the main gear. In a tricycle gear the c.g. is forward of the main gear. $\endgroup$ – Terry Jul 22 '20 at 21:29
  • $\begingroup$ @Ralph J, copy/paste that as an answer and you'll have my vote... $\endgroup$ – Michael Hall Jul 23 '20 at 1:38
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Tail wheel & tricycle are opposites. Tricycle configuration = has a nosewheel - as a child's tricycle has the single wheel to the front. This configuration is what's being discussed in the quoted text. From front to rear: nosewheel, then CG, then main gear. This works to prevent tailstrikes on takeoff & landing. What nosing over is with tailwheels, tail strikes are with nosewheels. The text is correct.

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  • $\begingroup$ Please check again, I have edited. Thanks for clearing the air but it is still a contradiction in text $\endgroup$ – Noorul Quamar Jul 28 '20 at 16:15
  • $\begingroup$ "What nosing over is with tailwheels, tail strikes are with nosewheels" I'd imagine prop repairs and engine checks are a bit pricier than empennage repairs, though. ;) $\endgroup$ – FreeMan Jul 28 '20 at 18:34
  • $\begingroup$ @Freeman Both are the undesirable consequences of an unintended excursion in pitch. For light aircraft you're almost certainly correct; for airliners, a damaged aft pressure bulkhead from a tailstrike on landing can run to many multimillions of $$$... potentially enough to result in a hull loss. $\endgroup$ – Ralph J Jul 28 '20 at 18:50

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