I am working on a technical documentary of sorts about the Boeing 707 and some of the information I need has been difficult to find, so I have some questions I'm hoping can be answered here.
1. The Boeing 707 received an extension to its tail fin as well as a ventral fin early in its service life to increase directional stability. I have read at least two conflicting reports as to why this was done, but no definitive data.
The two cases I have heard are:
a. The extensions were devised after the first Boeing 707-220 for Braniff crashed during a training flight during which the training pilot severely exacerbated dutch roll motion to the point of structural failure
b. The extensions were required by the British for their Boeing 707-420 aircraft because of poor directional stability in the engine out go-around situation at low airspeeds
Does anyone know specifically which scenario it was, or if it was something else entirely?
2. Does anyone happen to know which line numbers were the first to receive the modifications above?
Most all aircraft were retrofitted after the fact, but I could use information about which production aircraft rolled out of the factory with the modifications already done.
3. What was the actual reason that Boeing built the -138 for Qantas?
I have heard conflicting accounts of this one as well.
a. Qantas had inspected the Comet 4, DC-8, and 707. The Comet had a range too short for the needs of the airline, the DC-8 was too big and Douglas would not modify it, so they asked Boeing to make a 707 of the original length planned when the 707 was announced, to which they agreed.
b. Qantas had ordered the 707 with the intention of operated the aircraft with it's original length of 127 ft 10 in. Pan Am and other airlines petitioned Boeing to stretch the aircraft for more passenger load, but this shortened the range of the aircraft beyond what Qantas could use, so Boeing built the Qantas aircraft to original spec and all other -120 aircraft to the new lengthened spec.
4. Is there a comprehensive documentation of the different test programs accomplished by the 367-80, with dates?
The ones I am aware of (though unfortunately lacking much specific detail or more than a single source for each) are listed below:
- Tested the wing glove used on later 707 models (still there today)
Tested very high deflection flaps (70 degrees?) (Blown flaps?)
Tested several airfoil shapes
Tested reversed (upside-down) leading-edge slats on horizontal tail-plane
Tested engines used on later 707 models
Outfitted for testing with a single JT8D and Boeing 727 flaps and slats
Any information about these topics would be very appreciated!