60 years ago today

I wonder why the 707 seemed to be phased out sooner than the DC-8. They seem to have similar characteristics. I'm guessing they had similar life spans. Yet in the 1980s the Douglas DC-8s went on to have a second life as re-purposed cargo haulers for UPS, Emery, Airborne Express, etc. But I never saw any 707s in service in any capacity here in the US during the same time period.
 
Paulie said:
D

Dutch roll.
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When the airplane got into light turbulence it flexed at about 5hz, which turned out to be the optimum frequency for he average weight head to compress against the brain stem just right, causing a loss of vision/capability to interpret the instruments.
 
Paulie said:
Dutch roll.
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Strange that the 707 and KC-135 flew so differently.

The KC-135A had a simple stability augmentation system (and full bore autopilot) for all three axis. In addition to the rate gyro the yaw axis also had a lateral accelerometer to keep the plane coordinated. What's interesting is that you could launch the airplane without restriction without the autopilot/stab aug system, and the plane was manageable without it. No bad pfugoids, no dutch roll. It did wallow around in yaw at high AOA, such as on final, but the AFCS was not usually engaged below 3000' if memory serves. Some airplanes of the day (and probably still today) had to have a triple redundant yaw damper because without it the airplane could end up on its back.
 
JohnAJohnson said:
When the airplane got into light turbulence it flexed at about 5hz, which turned out to be the optimum frequency for he average weight head to compress against the brain stem just right, causing a loss of vision/capability to interpret the instruments.
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What was done to correct the problem?
 
Bill Jennings said:
What was done to correct the problem?
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Bill, I'm going from memory and I think it was lengthened slightly to change its resonant frequency, but I just can't remember that part and hopefully someone will chime in on the actual fix. The actual plane they had the problem with might have been the -80, or it could have been the first actual 707, again, I can't remember the details. Hopefully others might, because it was an interesting problem.
 
SkyDog58 said:
The FAA was created 60 years ago today on August 23, 1958.
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And has been friendly and helpfully making clear and understandable regs without causing the least bit of misunderstandings ever since.....
 
A
JohnAJohnson said:
Strange that the 707 and KC-135 flew so differently.

The KC-135A had a simple stability augmentation system (and full bore autopilot) for all three axis. In addition to the rate gyro the yaw axis also had a lateral accelerometer to keep the plane coordinated. What's interesting is that you could launch the airplane without restriction without the autopilot/stab aug system, and the plane was manageable without it. No bad pfugoids, no dutch roll. It did wallow around in yaw at high AOA, such as on final, but the AFCS was not usually engaged below 3000' if memory serves. Some airplanes of the day (and probably still today) had to have a triple redundant yaw damper because without it the airplane could end up on its back.
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American lost one in Jamaica bay ny due to Dutch roll. My dad was a investigator with the CAB (civil aeronautics board) and I remember when he got the call.
 
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