14
$\begingroup$

The spoilers on the Airbus A300 have large gaps at the bottom:

A300 wing
(A300-600R, modified from Wikimedia Commons, original picture by Tennen-Gas, CC BY-SA 3.0)

I have never seen any other aircraft with such gaps in the spoilers. Airbus also got rid of them on the A310:

A310 wing
(A310-322, ETH-Bibliothek Zürich, picture by Swissair, CC BY-SA 4.0)

Since the point of spoilers is to disrupt airflow on the top of the wing to reduce lift, it seems counter-productive to include such gaps. So what is their purpose?

$\endgroup$
2
  • 1
    $\begingroup$ I cannot answer with scientific accuracy, but the gaps do not diminish the efficiency of the spoilers in a significant manner, but relative to their size the pitching moment and actuation force required are smaller compared to a "solid" version. $\endgroup$
    – Jpe61
    May 31 at 9:49
  • $\begingroup$ What do dive brakes have to do with it???? $\endgroup$
    – John K
    May 31 at 23:38
10
$\begingroup$

Literature on the A300's spoilers is lacking, so is the flight manual's description. But based on publicly available information, there is a very strong candidate for a reason.


The A310's wing is very different from the A300's. Of the relevant differences, the A300's wing is:

  1. Thinner[1] (you can also visually tell: wing thickness under the deployed spoilers and spoiler thickness)
  2. Outboard section having double-slotted flaps (not on the later model -600R shown in the question)[2]

enter image description here
Three different A300/A310 flaps,[2] and A300 v A310 wing thickness[1]

Both of which when combined would lead to a spoiler mechanism packaging difficulty, which leads to smaller spoiler actuators. The A300's spoiler with a gap would lessen the low pressure behind the spoiler, making it easier to deploy and hold.

In fact, the inboard spoilers where the wing is thick, the spoilers are normal:

enter image description here
— Lufthansa Airbus A300 Landing Berlin Tegel (YouTube)


Another airliner with such a gap is the Caravelle VI-R. The gap is referred to as a breather slot:

[Spoilers] require holding open as the airflow tends to blow them closed. Some [spoilers] feature breather slots, e.g. the ones of the Airbus A300 and Sud Aviation Caravelle.[3]


1: Airbus FAST magazine #5 (PDF)
2: Aerodynamic Design of Airbus High-lift Wings in a Multidisciplinary Environment (PDF)
3: Alternative Air Brake Concepts for Transport Aircraft Steep Approach (PDF)

$\endgroup$
3
  • $\begingroup$ Beautiful answer, any idea why the A321 breaks with the flap-trend so obviously? $\endgroup$
    – ROIMaison
    Jun 2 at 11:53
  • 1
    $\begingroup$ Thanks @ROIMaison / See p. 7 of the second ref. In short, Airbus favors high-lift wings w/ simple flaps, but since the A321 came after the 320 (a stretched variant), to avoid redesigning the landing gear and to achieve similar performance the flaps were made double-slotted. Not in the ref.: a similar thing happened w/ the 350 stretch (the -1000) where they had to redesign the aft part of the wing. Boeing on the other hand favors high-lift flaps, which doesn't require changing when stretching models. See this post for more. $\endgroup$
    – ymb1
    Jun 3 at 2:20
  • 1
    $\begingroup$ Nice one. I even found a photo of the Caravelle with spoilers deployed. $\endgroup$
    – TomMcW
    Jun 4 at 17:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.