(Source: Boeing)
Many thanks to David Giba who shares the following via the Gary J. Cohen’s Shortwave Listeners Global Facebook page:
The Boeing 707 is my favorite commercial jetliner. If one looks at the tail they will see a probe pointing forward off the top of the tail. That is the HF shortwave antenna.
(Source: VIP Club)
It was matched by an antenna tuner/transmatch much like we have in our HF radios. This is the story of the Univac Coupler. Very interesting.
While a working airline avionics technician I took evening college courses toward a degree in aviation management. This was in the early 1980s. One instructor had put together an excellent, wide ranging course on industry-wide problems that had affected safety and how they were overcome. Unfortunately, he was convinced that he was infallible and in no need of further enlightenment. He pointed out the spike feature on an illustration of a B-707 and challenged the class to identify its function. After several attempts were made by students the classroom fell silent, so to get things moving I volunteered that it was a dual HF antenna. Mr. Know-it-all sneered and repeated my words as if they were heresy. “It is an aerodynamic boom,” he proclaimed, while the class looked at me in pity of my ignorance. That wise guy cost me a letter grade which was one of the two B’s I received in an otherwise all-A college career.
And it added just a little more class to a already classy lady.
Lets say like a ” pushup bra” on Dolly Parton!
Yes, no?
Automatic
Very nice antenna tuner. Is there a airplane junkyard I could get one?
One question. Is this automatic or does the pilot have to have radio knowledge of setting the SWR for each frequency he uses?
IIRC the original 707 prototype was known to Boeing as the “dash-80”.
It got initial airline orders for the 707…but then Douglas (who were a
year or so behind) brought out their DC-8.It was larger,had more powerful
turbojets and range.
Then it was found the 707’s had to be periodically re-skinned due to metal fatigue.
Boeing redid the 707 into the 720,with size,range and engines like the DC-8.
Meanwhile the “dash-80” tested the “all flying tail” refueling boom
(IIRC the prop KC-97 did,too) and became the KC-135 tanker.
Boeing never made much on the 707’s for the above reasons but reaped
the benefits with the 135’s…which had thicker skinning and still fly today.
Boeing’s test pilot was demo’ing the dash-80 for some airlines once and did
something really snazzy-he barrel rolled it: