B52 speed - indicated limit?
Significant Mach position errors exist at airspeeds above Mach 0.81 indicated due to the EVS pod installation. The pods create a region of localised supersonic flow in the vicinity of the pitot tube. This results in sensing a lower pressure and causes the airspeed and Mach indicating systems to read low. Therefore, the aircraft will not be flown at speeds greater than 0.84 Mach indicated to prevent exceeding the limiting Mach of 0.91 true.
If an airspeed calibration is made, the aircraft (clean or with cruise missile pylons) may be flown to 400 knots calibrated airspeed and 0.91 Mach true under conditions allowing 390 knots IAS and 0.84 Mach indicated. Cruise missile pylons with or without missiles have no effect on the previous limitations.
If an airspeed calibration is made, the aircraft (clean or with cruise missile pylons) may be flown to 400 knots calibrated airspeed and 0.91 Mach true under conditions allowing 390 knots IAS and 0.84 Mach indicated. Cruise missile pylons with or without missiles have no effect on the previous limitations.
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Thanks Megan for the very comprehensive answer.
The reason I was asking was this video below. (Which you've probably seen) The Boeing pilot says early on that they would be making low level 10minute runs at 280' 350 and 400 knots calibrated. All the civilian Boeings that I flew were limited to around 350knots indicated. I can't remember if it was exactly 350, it might have been. (737, 757, 767)
400knots indicated seemed very high, but you have confirmed that it was close to that, at 391 indicated. What was the noise level like at that speed? I wouldn't have felt very comfortable at 500feet at redline, I must confess!
The reason I was asking was this video below. (Which you've probably seen) The Boeing pilot says early on that they would be making low level 10minute runs at 280' 350 and 400 knots calibrated. All the civilian Boeings that I flew were limited to around 350knots indicated. I can't remember if it was exactly 350, it might have been. (737, 757, 767)
400knots indicated seemed very high, but you have confirmed that it was close to that, at 391 indicated. What was the noise level like at that speed? I wouldn't have felt very comfortable at 500feet at redline, I must confess!
The B727's I flew had a two position MMO/ VMO switch which
varied depending on zero fuel weight.
At the lower ZFW (don't remember that number)MMO was .9
and VMO 380 KIAS.
Above this weight it was .86 / 350 KIAS.
varied depending on zero fuel weight.
At the lower ZFW (don't remember that number)MMO was .9
and VMO 380 KIAS.
Above this weight it was .86 / 350 KIAS.
Last edited by stilton; 15th Aug 2017 at 06:43.
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At the lower ZFW (don't remember that number)MMO was .9
and VMO 380 KIAS.
and VMO 380 KIAS.
Yes the 727 was always quick, the 747 I think has a high IAS limit too.
We once tried to race an Air Force VC10 in a 757, negotiating with ATC our available speeds. That was embarrassing!
707-300 speeds
Vmo (Maximum Operating) KTS
at Sea Level 339
at 5,000 ft 344
at 10,000 ft 351
at 15,000 ft 359
at 20,000 ft 369
at 24,900 ft 378
Mmo (Maximum Operating) at 25,000 ft and above M = 0.887
Vmo (Maximum Operating) KTS
at Sea Level 339
at 5,000 ft 344
at 10,000 ft 351
at 15,000 ft 359
at 20,000 ft 369
at 24,900 ft 378
Mmo (Maximum Operating) at 25,000 ft and above M = 0.887
