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2015年7月21日 · I read an article that mentioned "VMO" speeds of a 747 and that the plane, when it exceeds its VMO, shakes uncontrollably and destroys itself. I've never heard of planes doing this and the article
2021年7月25日 · The speed of sound is decreasing because the air is getting colder (speed of sound in an ideal gas is proportional to the square root of the temperature). Both of these effects result in an increasing Mach number (M = TAS / speed of sound). Eventually, the Mach number will reach Mmo and now you are limited by Mmo rather than Vmo.
2016年11月4日 · The overspeed goes off when either the indicated airspeed exceeds that limit or the mach speed exceeds the mach limit. At least that's how it worked on 747-100/200 aircraft. The 350 knot figure for the max operating airspeed sounds reasonable to me as long as you're low. From memory that was around the max operating INDICATED airspeed for 747 ...
2018年4月23日 · No. It is usually determined by the onset of “Mach tuck”, the transsonic loss of lift caused by the flow speed over the wing becoming supersonic in too large region. It may be also determined by the TAS limit due to onset of aeroelastic flutter, because Mach number follows true airspeed more closely than indicated airspeed.
2.01.01 | INTRODUCTION Observance of the limitations contained in this chapter is required by law. When operating in accordance with an approved appendix or supplement to this manual, the limitations of this basic Airplane Flight Manual section apply, except as altered by such an appendix or supplement.
2015年6月4日 · The Vmo is 360 KIAS vs 602 KIAS corresponding to an Mmo of 0.91 at those altitudes. Presumably Boeing engineers in a buffer of 20% or so prior to the onset of control surface flutter, so that would allow for a maximum forward speed of 430-440 KIAS prior to the onset of control surface flutter.
VMO is given in IAS. You can convert MMO to an airspeed based on altitude, but really they are two independent limits, and whichever limit is lower at your altitude must be observed. Your max cruise speed data only makes sense if a TAS; converting it to a Mach number at the given cruise altitude reveals it is the same as MMO only expressed in TAS at given altitude.
2018年3月11日 · At VMO/MMO, the trim reference speed is limited by inhibiting trim in the nose down direction. Hand flying straight and level Pushing the thrust levers forward will result in a climb at the current speed due to the fly-by-wire design—only the trim buttons change the "trim reference speed".
2016年9月12日 · The generic answer is: Design Cruising Speed (Vc) = 33 * Sqrt (wing loading) Design Dive Speed (Vd) = 1.4 * Vc. Never Exceed Speed (Vne) = 0.9 * Vd. Then empiric testing (wind tunnel or test pilot) is done to test and expand those. Actual formulas are in the F.A.R. FAR/JAR-23 and a reference page with this question answered is in this forum.
3. Va limits G loads resulting from pilot input of maximum control deflection to limit load. Vno limits G loads caused by vertical gusts over 30 ft/sec, without pilot input, to limit load. In other words, Va protects you from bending the wings from pulling too hard, and Vno protects you from bending the wings from going too fast through bumps.
