PPRuNe Forums Questions to principles of flight

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 17th Oct 2012, 16:19 #1 (permalink) Probationary PPRuNer   Join Date: Oct 2012 Location: Bremen Age: 23 Posts: 2 Questions to principles of flight Hey guys, have some problems with the following 3 questions: 1) „An aeroplane in straight and level flight at 200 kt is subjected to a sudden disturbance in speed. Aussuming the angle of attack remains constant ititially and the load factor reaches a value of 1.21:“ Answer: the speed will have increased by 20 kt. 2) „Approximately how long does it take to fly a complete circle during a horizontal steady coordinated turn with a bank angle of 45° and a TAS of 288 kt?“ Answer: 95 s 3) ) „An aeroplane in straight and level flight at a speed of 2 VS. If, at this speed, a vertical gust causes a load factor of 3, the load factor n caused by the same gust at a speed of 1.2 VS would be:“ Answer: not greater than 1.44, because the aeroplane is stalled with a higher load facto rat 1.2 VS I have no idea how to figure it out.
 17th Oct 2012, 18:34 #2 (permalink) Join Date: Dec 2006 Location: Hamburg Age: 35 Posts: 346 Good luck!
 18th Oct 2012, 02:46 #3 (permalink) Join Date: Sep 2002 Location: Inland Posts: 919 Here's a solution to the first one. Load factor = L/W The factor went up by 21%, therefore the lift went up by 21% because the weight stayed the same. Lift is proportional to V squared. The equation would be, where V1 is 200kt and V2 is the new speed Lift 2 / Lift 1 = V2 squared/ v1 squared 1.21 / 1 = V2 squared / 40,000 so V2 squared = 40,000 x 1.21 = 48,400 giving V2 = 220 kt. For the subsequent questions, I dumped that sort of knowledge when I went from fixed wing to rotary, and stall speeds etc were irrelevant. Sorry.
 18th Oct 2012, 10:16 #4 (permalink) Join Date: Apr 2011 Location: NL Age: 27 Posts: 98 For q.2 refer to chapter 12 of the Oxford POF book. The 2 formulas needed are turn radius = V² / (g. °) and Rate of turn = TAS/ radius. everything in SI units and ROT in radians per second. This gives: (148m/s)²/ (9,81m/s² x tan45)= 2233 m. radius (148 m/s)/ 2233m= 0,067 rad/ sec. 2π rad is a full circle, so (2π)/(0,067 rad/ sec)= 94 seconds
 22nd Oct 2012, 16:21 #6 (permalink) Probationary PPRuNer   Join Date: Oct 2012 Location: Bremen Age: 23 Posts: 2 Thanks a lot my friends

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