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Old 8th March 2002 | 16:33
  #18 (permalink)  
Blip
 
Joined: Oct 2001
Posts: 308
Likes: 1
From: Australia.
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I would have thought that an absolute text book rotation rate would only be critical when at length or obsticle limit weight and you have an engine failure right at V1. After all, that is what all the performance figures are based on.. .. .Once you reach V1, every moment after that spent operating without an engine failure is bringing you further and further away from the edge of the required performance envelope.. .. .So if you've made it all the way to Vr and you still have all engines operating, bonus! I think in that case you can afford to REDUCE your rate of rotation from say 3 deg/sec to maybe 1 degree per second passing through 9-12 degrees nose up.. .. .So it takes an extra 2 seconds to reach the target attitude (3 seconds to pass through 9-12 degrees nose up instead of 1 second)(6.8 seconds not 5.6 seconds to reach 17 degrees nose up). So what. The recommended rate of rotation is 2.5 to 3 degrees per second for the B733 so there is a difference of 1.2 seconds for a rotation to 17 degrees nose up right there.. .. .If a reduction in rate of rotation when the tail is just 2 feet off the runway greatly reduces the chance of a tail scrape, and it's not absolutely critical for performance reqirements for the reasons stated earlier, I think it's a good compromise.. .. .Anyway I doubt whether people are actually stopping the rotation at 10 degrees nose up. I think it's just a matter of greatly reducing it for 3 seconds or so.. .. .If however you are taking off at limited weights and the brown stuff hits the spinning bits, then yes, you might have a point. But even then I come back to the point that it's only a matter of an extra 2 seconds to reach the target attitude (in this case 13 to 15 degrees or so).. .. .Maybe that sounds unreasonable. Tell me if it does and why. I always like to share ideas and learn.. . <img border="0" title="" alt="[Smile]" src="smile.gif" />
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