Aerosoft Aerosoft Team [Inactive Account] 51558 Posted December 23, 2009 Aerosoft Share Posted December 23, 2009 Just because somebody send this to me (Thanks!). Last question of the day, no prices to be won, enough freebies given out today! Most, if not every aircraft has a remarkable low amount of stability in the roll axis. In most aircraft it's the least stable axis, for many aerodynamic reasons that involve words like long tail slip effect etc (gliders know that one). Why don't aircraft designers fix this, what are they worried about? Surely a more stable aircraft that still corners well would be easier to handle. Link to comment Share on other sites More sharing options...
Carlos Domingos 4 Posted December 23, 2009 Share Posted December 23, 2009 this one is really hard! Link to comment Share on other sites More sharing options...
flyhigh 0 Posted December 23, 2009 Share Posted December 23, 2009 Well as far as I know a totally stable aircraft would be very hard to fly. The aircraft would be sluggish to respond to control inputs and the controls would be heavy as the aircraft would have a very strong desire to return to its neutral position. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted December 23, 2009 Author Aerosoft Share Posted December 23, 2009 this one is really hard! I'll give a hint that will only help some people. "think about me" Link to comment Share on other sites More sharing options...
RichardH 0 Posted December 23, 2009 Share Posted December 23, 2009 I'll give a hint that will only help some people. "think about me" Not a comfortable ride for the passengers maybe? They wouldn't get a nice smooth, rolling turn, it'd be pretty steep. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted December 24, 2009 Author Aerosoft Share Posted December 24, 2009 Not a comfortable ride for the passengers maybe? They wouldn't get a nice smooth, rolling turn, it'd be pretty steep. The first sentence is right, the second wrong. Link to comment Share on other sites More sharing options...
Dotsalgon 13 Posted December 24, 2009 Share Posted December 24, 2009 I believe that one of the reasons is the passengers comfort. But if an airplane would turn very steep and return to the center potition fast wouldn't that cause some G forces?? Who would wants G forces while drinking coffe??? If I am totaly wrong and stupid just ignore this hypothesis... Thanks Link to comment Share on other sites More sharing options...
Lennart B. 6 Posted December 25, 2009 Share Posted December 25, 2009 Maybe it´s about the passengers feeling quite uncomfortable when the wings flex pretty far due to the aileron forces, before the aircraft begins to turn? Link to comment Share on other sites More sharing options...
Guest inbrekers1 Posted December 25, 2009 Share Posted December 25, 2009 I know that in millitair aircraft they make the planes unstable so they far more agile. Most planes nowadays can't fly without electronics for keeping them stable. Link to comment Share on other sites More sharing options...
RodgerJohnson 11 Posted December 26, 2009 Share Posted December 26, 2009 You loose coordination? So your turns are no longer coordinated after any fix. -Rodger Link to comment Share on other sites More sharing options...
Alexander_Z 0 Posted December 26, 2009 Share Posted December 26, 2009 Rolls too fast, harder to keep the turn angle below 45 degrees, G-Forces and Overstress of the aircraft, since a turn is the most "stressful" maneuver... also, the aircraft might have a larger chance to turn too much and "flip"! And also also, since during a bank, one wing looses lift while the other gains lift, so that would put a lot of pressure and stress on the wing that is gaining lift... just look at how many problems the 787 had with the wings flexing... Link to comment Share on other sites More sharing options...
Kenneth 18 Posted December 26, 2009 Share Posted December 26, 2009 Rolls too fast, harder to keep the turn angle below 45 degrees, G-Forces and Overstress of the aircraft, since a turn is the most "stressful" maneuver... also, the aircraft might have a larger chance to turn too much and "flip"! And also also, since during a bank, one wing looses lift while the other gains lift, so that would put a lot of pressure and stress on the wing that is gaining lift... just look at how many problems the 787 had with the wings flexing... More lift does not imly mor stress on the aircraft wings if we do not consider the windspeed component(drag). More lift = the plane moves upwards with the same pitch, or in you're case, turns and roll the aircraft. As what i know the aircraft boddy has the same weight in slow and and higer lift. I can not see that a roll and turn makes higer stresses on one wing. What makes stress on wings is higer or lover G, to make a negativ or Positive G, you have to change the pitch constantly. A roll does not change the pich, but you change a pitch in a turn, and that is why you are being forsed down in a aircraft that is in a turn. As long as you are in a turn, you have positiv "changing" pich. It's the change in pitch that makes stress. Link to comment Share on other sites More sharing options...
Alexander_Z 0 Posted December 26, 2009 Share Posted December 26, 2009 More lift does not imly mor stress on the aircraft wings if we do not consider the windspeed component(drag). More lift = the plane moves upwards with the same pitch, or in you're case, turns and roll the aircraft. As what i know the aircraft boddy has the same weight in slow and and higer lift. I can not see that a roll and turn makes higer stresses on one wing. What makes stress on wings is higer or lover G, to make a negativ or Positive G, you have to change the pitch constantly. A roll does not change the pich, but you change a pitch in a turn, and that is why you are being forsed down in a aircraft that is in a turn. As long as you are in a turn, you have positiv "changing" pich. It's the change in pitch that makes stress. Yes, very sorry, I don't know what I had been drinking! Thanks for correcting me, my theories were all messed up, and one got mixed in with another! Thanks again. But a turn/bank still does put stress on the frame, it's just lift that doesn't do so. Link to comment Share on other sites More sharing options...
SimPilot767 157 Posted December 27, 2009 Share Posted December 27, 2009 Most and biggest movements during a flight happen on the "roll-axis", so if you add too much stability an this axis you would need much bigger deflections of the ailerons with all it´s disadvantages and drag. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted December 27, 2009 Author Aerosoft Share Posted December 27, 2009 Most and biggest movements during a flight happen on the "roll-axis", so if you add too much stability an this axis you would need much bigger deflections of the ailerons with all it´s disadvantages and drag. Closing the question without a winner. The answer is that increasing the stability on that axis greatly increases the chance to experience "Dutch Roll". Not a highly dangerous thing in it self but it is one of the most uncomfortable things passengers can experience. I myself get sick after just a few moment. And I have some experience with aerobatics without problems! Link to comment Share on other sites More sharing options...
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