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44 votes

What is this hole at the front of the engine pylon on a Boeing 707?

This is because those engines have turbocompressors which are used to supply cabin air. The engine bleed air drives the turbine of the turbocompressor, which in turn would drive a compressor which ...
aeroalias's user avatar
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39 votes
Accepted

Was it possible to land a Boeing 707 with 300 feet cloud ceiling in the 70s?

ILS approaches were in common use in 1970 when I got my instrument rating. The normal (Cat I) ceiling minimum was 200 feet. So, yes, a 707 would have been able to land with a 300 foot cloud ceiling in ...
Terry's user avatar
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28 votes
Accepted

What are those half-vanes in the engine inlet of a 707-328?

You have a very interesting find there! It is in fact not an engine from a B707, but a Kuznetsov NK-8 from Russia. It was used in Ilyushin Il-62 and Tupolev Tu-154 aircraft. As for the intermediate ...
Jpe61's user avatar
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27 votes

What is this hole at the front of the engine pylon on a Boeing 707?

Wikipedia tells you the answer: The 707 uses engine-driven turbocompressors to supply pressurized air for cabin pressurization. On many commercial 707s, the outer port (number 1) engine mount is ...
Penguin's user avatar
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24 votes

Why did Boeing choose to give the Boeing 720 such a designation?

Because the launch customer, United Airlines wanted it. From Boeing frontiers: The 720 was a ... first marketed to the airlines as the model 707-020. United Airlines was very interested in the 707-...
aeroalias's user avatar
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16 votes

What is this hole at the front of the engine pylon on a Boeing 707?

Turbo compressor drive was provided by 16th stage air (high pressure, high temperature) from its respective engine. 16th stage air was also used for: engine anti-icing, thrust reversers, fuel heat, ...
Loren's user avatar
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14 votes
Accepted

Why was the DC-8-70 successful, but not the 707-700?

I think there is a bit of a misconception in your question. The DC-8 was already out of production by the time the CFM56 was developed, so all of the DC-8 70 series are actually just retrofits of the ...
TomMcW's user avatar
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11 votes

4 Boeing 707 for $50,000. Is that possible?

Its surely possibly and there are a few things I can think of off hand, Missing Log Books: generally speaking if an aircraft is missing its log books you need to do quite a bit of tear down and ...
Dave's user avatar
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9 votes

What is this mysterious thing on the vertical stabilizer of the Boeing 707?

It is the high-frequency shortwave antenna of a 707-321B, specifically Clipper Yankee Ranger N418PA. Also present on the KC-135. You can read about the Antenna Coupler Program from the people ...
Party Ark's user avatar
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5 votes

4 Boeing 707 for $50,000. Is that possible?

Actually $50,000 is a good price, at least for scrap. If the empty weight of each jet is approx 130,000lbs and aluminum sells for roughly 25 cents on the pound of scrap, that gives a scrap value for ...
Romeo_4808N's user avatar
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5 votes

What is the difference between the series and parallel yaw-damper systems for the 707?

A serial system takes inputs, generates outputs, and there is no feedback to the input. A parallel system is a subset of a larger system, where the parallel system outputs also change the inputs. ...
Koyovis's user avatar
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4 votes
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Why no CFM-56 for the E3?

As mentioned in another answer to your question, the mission requirements for the two planes are different. The maximum takeoff weight of the KC-135 puts a limit not only on its range but also on the ...
Steve Pemberton's user avatar
4 votes
Accepted

Why is the 707’s yaw-damper-out lateral controllability marginal to nonexistent with flaps and spoilers extended?

Dutch roll is rolling, yawing and pitching together in a sort of Lazy 8-like pattern, and if divergent or really severe, there are very few humans that can make the perfectly timed in-phase inputs ...
John K's user avatar
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3 votes

How to identify a specific 707 variant?

Don't know about the interior shots but for the exterior: In-flight shots use a model, some ground shots use N6723, c/n 18989/492, a TWA 707-131B. This is from the awesome website IMPDb Internet ...
TomMcW's user avatar
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3 votes

Why did Boeing choose to give the Boeing 720 such a designation?

The 720 first flew before the 727 project began. At that time, there was no "7x7 series" – just the 707. (The 717 passenger plane didn't come along until the 1990s, though the internal ...
David Richerby's user avatar
3 votes

Why was the DC-8-70 successful, but not the 707-700?

When in the test program, the reason given was the DC-8, series 60, had a longer life span than the commercial 707 aircraft existing. The KC-135 had a lot less time on them. Worked on the program ...
user67480's user avatar
3 votes

Why was the DC-8-70 successful, but not the 707-700?

It isn't an issue with the engines, but rather a question of why the DC-8 was more popular and common in commercial service, long after the 707. You identified the key in your question: the KC-135 (-...
user71659's user avatar
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3 votes

What is this hole at the front of the engine pylon on a Boeing 707?

The key to answering your question is the weight of the TC.The first B-707 (N-70700) and early models that followed had no turbo compressors installed; same for the Air Force A & B KC-135s. These ...
Loren's user avatar
  • 735
2 votes

Why is the 707’s yaw-damper-out lateral controllability marginal to nonexistent with flaps and spoilers extended?

Why is the 707 so difficult to control with the yaw damper inoperative and flaps and spoilers extended? It is a matter of time constants and stability of responses: Stable responses return to ...
Koyovis's user avatar
  • 61.8k
1 vote

Why no CFM-56 for the E3?

I do not have access to material that would definitely prove the following in the specific case of the E-3 Sentry, but: As I understand the original USAF versions were delivered with T33 and the UK, ...
Jpe61's user avatar
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1 vote

Why is the 707’s yaw-damper-out lateral controllability marginal to nonexistent with flaps and spoilers extended?

While each aircraft is different, especially for ones with high amount of sweep, some general trends can still be predicted: The Dutch-roll damping decreases with decreasing speed (Ref. Etkins, ...
JZYL's user avatar
  • 11.1k
1 vote

4 Boeing 707 for $50,000. Is that possible?

According to the article, they were classified as unrecoverable, damaged, had missing parts, didn't fly since 2006, and the EW system dated back from 1984. Old aircraft (and other large hardware, ...
Therac's user avatar
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