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 10 707 autopilot rocking (Read 13678 times)
Prevost1
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707 autopilot rocking
Oct 22nd, 2010 at 4:00pm
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How in the world do you get the 707's a/p to stop the "rocking" movement? Only on the roll axis. Pitch, and yaw seem fine.
  
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Tim Capps
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Re: 707 autopilot rocking
Reply #1 - Oct 22nd, 2010 at 5:51pm
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I've seen this twice, both when I was heavy and at 35,000 feet or higher.  Otherwise not.  How high are you when this happens?
  

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Re: 707 autopilot rocking
Reply #2 - Oct 22nd, 2010 at 5:58pm
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Agreed, Tim. I'm only able to rock the lady with full load of any kind and well above 30.000ft where nobody would take her with a clear mind on that load.
The speed decreases and the rocking starts. Typical flight sim "too high for this GW" reaction. No bug or fault here, just a bad pilot.

Prevost1, we could use some more data on this then.
  
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Markoz
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Re: 707 autopilot rocking
Reply #3 - Oct 23rd, 2010 at 12:23am
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I saw a very gently rocking at FL390 (level flight). My 707 Gross Weight was between 185,000 pounds and 190,000 pounds. It was very slight, I had to look closely from outside (Locked Spot View) to actually see it. So far, I have only noticed it that one time.

Mark
  

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Re: 707 autopilot rocking
Reply #4 - Oct 24th, 2010 at 2:24am
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I second that, rocking seems to happen at high FLs and low speeds. it happenned to me twice, once with a heavy plane, and the second time with a fairly empty one (195,000 lbs @ FL370).

Cheers

Nico.
  

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Re: 707 autopilot rocking
Reply #5 - Oct 24th, 2010 at 10:27am
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I can confirm this is caused by exceeding performance limitations as well.  Out of curiosity I tried taking the 707 up to FL370 with a gross weight over 285,000 pounds and it started rolling left and right a few degrees above FL350.  Descending back to FL330 eliminated the motion.
  

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Re: 707 autopilot rocking
Reply #6 - Oct 24th, 2010 at 3:05pm
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Maybe the autopilot is struggling to hold it straight because the 707 is too "fat" to be at that altitude. I know when mine did it, my airspeed was about 248 KIAS. I know I wasn't doing 250 KIAS because I was using full throttle the nose was slowly settling down as my speed crept up to and above 250 knots. It never got fully stable until I started my descent.

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Re: 707 autopilot rocking
Reply #7 - Oct 24th, 2010 at 4:03pm
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I fly between FL 280 and FL 340 and have never had any rocking what so ever in this plane
  

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Re: 707 autopilot rocking
Reply #8 - Oct 26th, 2010 at 11:47am
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I was at a relatively low altitude and i believe it was pilot error. After a few minutes sorting things out, it subsided. By the way, how do you load or unload the fuel amount on the 707?
  
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Re: 707 autopilot rocking
Reply #9 - Oct 26th, 2010 at 1:51pm
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Prevost1 wrote on Oct 26th, 2010 at 11:47am:
By the way, how do you load or unload the fuel amount on the 707?

Not quite sure what you mean.

1. With the ALT > Aircraft > Fuel and Payload. However. This is not what I think you mean.

2. I fill the tanks from the outside to the inside. So I start by putting fuel in the Left Tip & Right Tip, then Left Aux & Right Aux, then Left & Right and finally Center.

If I'm doing it wrong, feel free to correct me. I do it that way because the 757 and 767 use the Center tank fuel first, before using the Left and Right tank fuel.

Mark

  

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Prevost1
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Re: 707 autopilot rocking
Reply #10 - Oct 26th, 2010 at 4:03pm
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Markoz,

alt, aircraft, fuel, payload is the info I needed
Thanks again my friend
  
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Markoz
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Re: 707 autopilot rocking
Reply #11 - Oct 26th, 2010 at 10:28pm
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The best info I have found to assist in things like that is in the 707perf.zip. You can get it at Avsim. Just go there, do a search for it and download it.

Mark
  

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Re: 707 autopilot rocking
Reply #12 - Oct 28th, 2010 at 2:50pm
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I will get that. Thanks
  
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Re: 707 autopilot rocking
Reply #13 - Nov 3rd, 2010 at 11:40am
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Markoz,

Weight is the key element in flying the 707. After I got my fuel weights down some from full tanks, everything seems to be fine. Thanks my friend......
  
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Re: 707 autopilot rocking
Reply #14 - Nov 3rd, 2010 at 11:06pm
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I have found that the 707 will rock gently if I slow down too much on approach too. I use it as a way of figuring out the Airspeed versus Weight versus Maximum Altitude when at cruise altitude and Airspeed versus Weight on Approach. In some ways you could refer to the gentle rocking left and right as a sort of Stall Warning. The info from the documents in the 707perf.zip file are vary somewhat from the Captain Sim 707, specifically Max Altitude at the stated weights. I fly about 1000 feet to 2000 feet below what those docs say and the rocking issue doesn't happen.

Mark
  

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