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Christopher Low

Excessive speed during ascent

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At the moment, I am limiting my cruise altitude for short flights around the UK to 5000 feet (so that I can enjoy the scenery). However, I have noticed that the speed of my aircraft increases excessively during this short climb, even though I have the upper limit set at 220 knots (slightly lower than the 240 knots normal limit; this is an adjustment to compensate for slightly slow photoscenery texture load times). My aircraft quite often accelerates to 260 knots by the time that power is reduced as I approach 5000 feet, and it makes me wonder if I am missing something. Can anyone tell me if this is normal, or if I should be doing something to correct it?

For the record, I set the MCP SPEED knob to the V2 figure before take off (as instructed).

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2 hours ago, Christopher Low said:

At the moment, I am limiting my cruise altitude for short flights around the UK to 5000 feet (so that I can enjoy the scenery). However, I have noticed that the speed of my aircraft increases excessively during this short climb, even though I have the upper limit set at 220 knots (slightly lower than the 240 knots normal limit; this is an adjustment to compensate for slightly slow photoscenery texture load times). My aircraft quite often accelerates to 260 knots by the time that power is reduced as I approach 5000 feet, and it makes me wonder if I am missing something. Can anyone tell me if this is normal, or if I should be doing something to correct it?

For the record, I set the MCP SPEED knob to the V2 figure before take off (as instructed).

What is the FMA telling you during climb?  In a climb, speed is usually controlled by pitch and power is set to a thrust limit.  Basic airmanship:  Performance = Pitch + Power.  Your mode of pitch control is given my the FMA.

I don't mean to be rude and I mean this with all kindness, but your airmanship skills need much work.  Basic airmanship means you understand stick and rudder concepts.  I know I've pointed you towards the AIM in the past; well, I still think you need to do some studying of basic skills.

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I am sure that my airmanship skills do need some work.....but then I am not doing this to become a real world pilot. I am doing it for fun. Now, it seems that you are saying that I need to keep the nose up to control the acceleration, and that is fine. I will try that next time, and see if I can keep the speed down. I had assumed that the autothrottle would keep the speed from getting out of hand, but I guess that this particular assumption was misguided :wink:

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29 minutes ago, Christopher Low said:

I had assumed that the autothrottle would keep the speed from getting out of hand, but I guess that this particular assumption was misguided

Yup, check your FMA and you'll see that during climb it says N1, which means it is providing a set thrust rating such as CLB.  Don't make assumptions, please try to learn the basics and you'll have much more fun.

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The overspeed problem occurs when the autopilot has been engaged. That being the case, I am not supposed to touch the yoke to keep the nose up. Are you saying that I need to manually alter the trim setting during the climb? Isn't that rather defeating the purpose of the autopilot?

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2 hours ago, Christopher Low said:

The overspeed problem occurs when the autopilot has been engaged. That being the case, I am not supposed to touch the yoke to keep the nose up. Are you saying that I need to manually alter the trim setting during the climb? Isn't that rather defeating the purpose of the autopilot?

No, he is not. He's simply explaining some basic flight physics. The only thing I've seen Dan ask you to pay attention to is the FMA, and the AP modes. So far, I haven't seen any responses from you that indicate what the plane is trying to do. If you put it in a mode you don't understand, you're likely going to get results you don't understand.

Earlier, you mentioned that you do this for fun. This is fine. All the same, if you don't treat the plane realistically because you're just having fun with it, it's not necessarily going to read your mind and behave predictably because it realizes you're just here to have fun, instead of going for the absolute realism.

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I am following the procedures stated in the Tutorial #1 to the letter. I assume this means that I am treating the plane realistically. I don't really know what else to say :huh: However, I will check to see what is displayed on the FMA and MCP during my next flight, and try to get you some more information.

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4 minutes ago, Christopher Low said:

I am following the procedures stated in the Tutorial #1 to the letter. I assume this means that I am treating the plane realistically. I don't really know what else to say :huh:

The tutorial isn't the flight you're on.

5 minutes ago, Christopher Low said:

However, I will check to see what is displayed on the FMA and MCP during my next flight, and try to get you some more information.

Yep. We can't really help you unless you give us more info on what the plane thinks it should have been doing. That's what matters, particularly when you're on AP, since what the plane thinks it's supposed to do is going to be what it does. When you're not in tune with that (as it seems you were not - no offense, but since you didn't immediately provide the FMA indications, it's not an unreasonable assumption), you're likely to be surprised, as it seems you were.

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On a side note, when I go through the setup procedure for my flights, CLB-2 is automatically selected after I have clicked on the TO-2 derate (and added the temperature at the top). However, I have been selecting CLB-1 (since the Tutorial #1 states that it should be selected if this has not automatically been done). I think that I am misreading that bit in the tutorial, so I need to try and understand it better...

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1 hour ago, Christopher Low said:

On a side note, when I go through the setup procedure for my flights, CLB-2 is automatically selected after I have clicked on the TO-2 derate (and added the temperature at the top). However, I have been selecting CLB-1 (since the Tutorial #1 states that it should be selected if this has not automatically been done). I think that I am misreading that bit in the tutorial, so I need to try and understand it better...

Tutorial #1 was written for the specific scenario noted in the tutorial. The whole concept of modifying thrust levels (either by de-rate or assumed temp) is to adjust to the particular airport, on that particular day, at that particular temperature, in that particular wind, at that specific weight, after you ate that particular meal. Don't simply copy concepts. Understand them.

Forcing CLB-1 is likely giving you a lot more thrust than you really need (there's a reason the automagic selected -2 for you). If you're going to rely on the automagic, then you should rely on it without trying to force your own ideas on it. If you're going to force it to listen to you, then you should probably know why you're doing it.

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Thanks, Kyle. It was the "if CLB-1 has not been automatically selected, then select it now" comment in the tutorial that fooled me. This could be a reason why I am overspeeding on the initial climb, so I will check that out tonight.

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4 minutes ago, Christopher Low said:

Thanks, Kyle. It was the "if CLB-1 has not been automatically selected, then select it now" comment in the tutorial that fooled me. This could be a reason why I am overspeeding on the initial climb, so I will check that out tonight.

Shouldn't be the sole cause. Do watch the FMA carefully, and be very specific about what you are doing, and what you are expecting when you post a response later, after trying again.

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Switching from CLB-1 to CLB-2 solved the overspeed problem during the initial climb to 5000 feet. The speed stayed at a comfortable 185-190 knots, and then slowly increased to 240 when I adjusted the value on the MCP. I noticed that the engines did not "surge" this time when passing through 1500 feet.

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15 hours ago, Christopher Low said:

I noticed that the engines did not "surge" this time when passing through 1500 feet.

Yep. This is one of the reasons the plane auto-selects a CLB value. It selects a value that does not produce an increase in thrust at the CLB change.

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