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Video answers: Why the 737 doesn’t have landing-gear doors

Here are the answers to last Friday’s video, enjoy!

Suggested ICAO level for video: 5+

  1. Boeing wanted the 737 to be low to the ground, as a result they realized that they didn’t have enough space for landing-gear doors.
  2. They’re heavy and complex, making the plane heavier and more likely to have a problem and cause delays.
  3. No, the landing-gear doors cover the wings and landing gear struts, but not the wheels.
  4. Boeing engineers decided to place hubcaps on the wheels to reduce the drag.
  5. If the hubcaps are lost there is a significant fuel penalty that the pilots have to apply to the flight plan.
  6. Boeing uses rubber blade seals to remove the gap between the wheel and the wheel-well bay.
  7. As the main landing gear is retracted, the brakes are applied to stop the wheels spinning.
  8. Icing doesn’t affect the wheels as the aircraft flies because that’s not an area of the plane that typically suffers from icing. Icing usually forms on wing leading edges, horizontal stabilizers, tail fin and the nose.

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Video: Why the 737 doesn’t have landing-gear doors

This week’s video describes why the 737 doesn’t have landing-gear doors and why that works.

Try to answer the following questions about the video and come back on Monday for the answers.

Suggested ICAO level for video: 5+

  1. What made Boeing decide not to use landing-gear doors?
  2. What are some of disadvantages of landing-gear doors?
  3. Is the 737 landing gear completely uncovered?
  4. What did Boeing do to reduce the drag created by the exposed tyres.
  5. What happens if this solution is lost?
  6. What solution did Boeing create to prevent objects being thrown into the wheel-well bay?
  7. What happens to the main landing gear wheels as they’re retracted?
  8. Why doesn’t icing affect the tyres as the aircraft is in flight?

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Have a great weekend!

Why does the Boeing 737 not have any landing-gear doors?

Paid promotion: https://brilliant.org/mentourpilot/ Have you ever seen a Boeing 737 take off and noticed that the wheels are still visible after the gear has been retracted? In this video I will tell you all about the reason for this, the aerodynamic impact and some protection systems that you might not know about.

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Structure: ‘must have’ & ‘can’t have’

This time in our structure help we talk about using ‘must have’ and ‘can’t have’. When we think about these two modals we think about them in relation to obligations for must, and ability for can. However, as with all modal verbs, there is more than one meaning. In addition to the above uses, we can use these modals in relation to probability / certainty. Both of these expressions relate to the past. ‘Must have’ expresses a high level of certainly that something was true or that it happened. Look at the following examples.

He is more than an hour late, he must have forgotten the takeoff time.
They arrived at the hotel after 2am, they must have been exhausted.

In both of these examples the speaker expresses a high level of certainty about what is said by choosing to use ‘must have’ (+ past participle). If the speaker isn’t so such, there are other expressions the can be used, however, the choice of expression here indicates a high level of certainty to the listener(s).

‘Can’t have’ (+ past participle) expresses a high level of certainty that something wasn’t true or didn’t happen. In this sense our two expressions represent opposites to each other. Look at the following examples.

His result in the test was bad, he can’t have studied for it.
They almost hit the animal while landing, they can’t have seen it until the last second.

Similarly in this case, the expression chosen indicates a high level of certainty that something wasn’t true or didn’t happen, other expressions exist to indicate different levels of certainty.

Now try to write some of your own examples using these two expressions.

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Have a great day!

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Video answers: Overnight shipping

Here are the answers to last Friday’s video, enjoy!

Suggested ICAO level for video: 5+

  1. It’s an enormous company with more planes than Etihad, Emirates and Qatar Airways combined, approximately 650 planes serving 400 destinations.
  2. The superhub is in Memphis and is located there because it’s close to the mean population centre of the US.
  3. Hundreds of flights arrive there and are unloaded between 10pm and 1am. Then the packages are sorted for planes to begin taking off again between 2am and 4am.
  4. To operate to smaller destinations, smaller ATR and Cessna planes are used, which connect to the bigger hubs.
  5. No, not every package is sent through the superhub, secondary hubs help reduce the inefficiency of sending everything through the superhub.
  6. It’s very important because it’s directly between FedEx’s hubs in Memphis and Osaka, Japan and it’s heavily used as a location to refuel, swap crews and sort packages.
  7. They buy these aircraft because they’re cheap and often don’t fly for many hours during the day, which would lose the company money if they had more expensive planes.
  8. In general, it’s not the same for commercial airlines, which generally buy more expensive planes and use them for as many hours per day as possible. However, some airlines buy cheaper planes and can use them less while still making a profit.

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Video: Overnight shipping

This week’s video describes how overnight shipping works. Watch to find out how!

Try to answer the following questions about the video and come back on Monday for the answers.

Suggested ICAO level for video: 5+

  1. How big is FedEx?
  2. Where is FedEx’s superhub and why is it located there?
  3. How does the superhub operate?
  4. How does FedEx operate to smaller destinations?
  5. Is every package sent through the superhub?
  6. Why is Anchorage so important to FedEx?
  7. Why do FedEx and other shippers buy old aircraft?
  8. Is this the same for commercial airlines?

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Have a great weekend!

How Overnight Shipping Works

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Structure: Rise vs Raise

This time in our structure help we talk about the difference between the verbs ‘rise’ and ‘raise’. They look similar and have the same meaning but there is, as always, a difference in the way we can use each. Let’s take a look.

While both of these words mean the same thing (to move upwards), rise is an intransitive verb, meaning it can’t have an object. Look at these examples.

The sun rises in the morning.
The plane rose (past simple) into the sky and disappeared.

In these sentences there are no objects, the sun doesn’t rise anything, it performs the action without having a direct effect on anything (in relation to elements in our sentence). The situation is the same with the plane.

Now let’s look at raise, which is a transitive verb and can have an object; so you can raise something. Let’s look at some examples.

The passenger raised his bag into the overhead storage bin.
The copilot raised his hand to ask a question.

In these sentences there are objects – sentence elements – which are affected by the action; the bag in the first example and the hand in the second example.

Extra
Depending on how you think about your sentence, it may be possible to use either verb. Look at the following examples;

Ticket prices rose last month.
The airline raised ticket prices last month.

Now try to write of some of your own examples.

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Have a great day!