757 Captain III >> 757 Captain III (P3D4 & general) - Bug Tracking >> SYSTEMS & DYNAMICS

Message started by Captain Sim on Dec 24th, 2018 at 5:08pm

Post by g5flyer on Jan 11th, 2019 at 5:41am

g5flyer wrote on Dec 28th, 2018 at 10:54pm:
I just noticed something while beating up the pattern. The flap maneuver speed "F" is showing the same speed as the minimum maneuver speed "top of the yellow bar" along the speed tape. Just wanted to point it out . I have attached a pdf that shows the illustration of the topic at hand.

Just re-cheked, all the bars show exactly what they supposed to show. The proof attached. Are we missing something?

So going back to your response to the maneuver speeds. One thought, you should never be flying a flap maneuver speed and be inside of the amber range. The top of that amber range is a 1.3g shaker/buffet onset speed. Shaker below 20,000ft and buffet above 20,000ft. 1.3g just means it's a speed at 40 degrees of bank which requires 1.3g of force from the yoke to maintain altitude. This speed gives you stall protection in up to 40 degrees in case you need it. Lets look at your example of 220,000 pounds.

The stall speed for 220K below 8,000ft at flaps 15 is 119KTS. This is a 1.0g speed, meaning wings level no yoke force applied. We need to figure out what the stall speed is in this situation at 40 degrees of bank because it obviously increases with bank as you adjust the lift vector away from directly opposing gravity and a wing is slower than the other in a sense. At 40 degrees of bank, you are looking at about 15 to 17 percent increase of stall speed from 1.0. 119 X 1.17 is 139KTS. Shaker and onset starts about 7 to 9 knots above stall. You are looking at a minimum maneuver speed of of 146 to 148 knots for your top of the amber range.  Your F would be 160 and your top amber is 148 at the most.

So again, you should not be in that amber band. The only time you should be close is during configuration changes on clean up. As you move the flap handle from 15 to 5, the system sees your handle position at 5 and the amber adjusts to flaps 5 minimum maneuver speed which puts you close as you are accelerating. Flight manuals tell you that if at anytime you are below minimum maneuver for existing configuration, limit your bank to 15 degrees because you don't have that 40 degree bank protection as you suck the flaps up until you reach the new speed. This was standard during takeoffs when I flew DC10s. If I needed to turn during takeoff, I would accel to flap retract speed, maintain my takeoff flaps and make the turn at flap retract speed. Once able to shallow back to 15 degrees bank, I called for flaps up for accel. I attached a PDF to help you see what I did. 

Thanks, we'll check.;file=757.pdf ( 197 KB | 15 Downloads )

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