Talk:Spoiler (aeronautics)

Open spoiler photo caption

The photo of the open spoiler is a good example.

But shouldn't the caption explain that the spoiler is the raised surface on the right and not the lowered surface on the left (which is a flap)?

Another possibility might be to mark the spoilers somehow on the image, e.g. using a red marking along their edges?

Penedo 05:14, 1 February 2006 (UTC)

Air brakes

Air brakes are inboard spoilers, I don't think there should be just a hard and fast differentiation between air brakes and spoilers. When you are airbraking on the ground you extend both inboard and outboard spoilers, (or the armed hydraulic system does, after it detects weight on wheels in an airliner), if you are spoiling off speed in the air uses a subset of your spoilers, usually outboard. --Omnicog 18:48, 23 May 2006 (UTC)

Gliding

In modern gliders (sailplanes) the spoilers—if that's what they are—are invariably called air brakes. The term spoilers is associated with much older gliders. --NigelG (or Ndsg) | Talk 14:32, 2 July 2008 (UTC)

Missing information

I'm no expert or anything, but reading some accident reports (like Air Canada Flight 621), it seems this article is missing relevant information, for example about "arming and deploying the spoilers", the dangers of premature deployment, the reasons for crews not following prescribed procedures (like hard touchdowns when spoilers deployed on DC8) the changes in regulations following accidents and the safety mechanisms that have been developed over the years. 84.197.187.119 (talk) 17:54, 24 August 2011 (UTC)

Spoilers on gliders

On 1 November the paragraph which began “Spoilers are used by nearly every glider (sailplane) ...” was deleted with the edit summary “Gliders do not have spoilers, they have airbrakes.” See the diff.

The first paragraph of the article states Wikipedia’s perspective on the subject. It states: Spoilers are plates on the top surface of a wing which can be extended upward into the airflow and spoil it. By doing so, the spoiler creates a carefully controlled stall over the portion of the wing behind it, greatly reducing the lift of that wing section. Spoilers differ from airbrakes in that airbrakes are designed to increase drag making little change to lift, while spoilers reduce lift as well as increasing drag. The drag-increasing devices used on nearly every glider qualify perfectly under these criteria for what constitutes a spoiler so I have reverted the deletion. What do others think?

The paragraph in question, and the article in general, are significantly under-sourced. Does anyone have a good source for all this information? If so, feel free to cite the source in an in-line citation. Dolphin (t) 01:19, 1 November 2012 (UTC)

Many high-speed aircraft, and particularly military aircraft, have airbrakes that deploy out of the fuselage. These airbrakes are adequately effective because of the generally high speed of the aircraft, and because they are used when the aircraft is moving at very high speed. (High-speed aircraft mostly use partial-span, trailing edge wing flaps for adjusting lift and drag at low speeds, such as takeoff and landing.) Gliders are low-speed aircraft so airbrakes that deploy out of the fuselage would not generate adequate drag for landing. It is necessary for glider designers to find a source of greater drag. This is nearly always done by reducing the effective aspect ratio of the wing and increasing the lift-induced drag – the glider pilot is able to extend devices out of the wing surfaces and these devices spoil the lift previously generated by a significant portion of the wing. (These devices act as spoilers, even though many glider pilots call them airbrakes.) This causes trailing vortices either side of the spoilers and significantly increases the lift-induced drag.

Naturally, the spoilers also cause an increase in parasite drag, just as they would if they were airbrakes deployed out of the fuselage. However, if airbrakes of the same frontal area were deployed out of the fuselage of a glider they would not significantly influence the lift induced-drag and would be much less effective than spoilers deploying out of the wing.

Glider pilots may choose to call them airbrakes, but Wikipedia has given its criteria for what constitutes a spoiler and what constitutes an airbrake. The drag-producing devices on most gliders qualify as spoilers under Wikipedia’s criteria. Dolphin (t) 01:44, 1 November 2012 (UTC)

Thank you for your comments. The devices that I have seen on glider wings were small plates extending above and below the wing acting, it seemed to me, purely as airbrakes (some aircraft, e.g. the Avro Vulcan, used similar devices). However, I freely accept your more expert view. --DesmondW (talk) 09:07, 1 November 2012 (UTC)

I am going to expand on this a little. The devices that I have seen on gliders, and also on the Avro Vulcan, have arms that space the plate from the wing. See http://en.wikipedia.org/wiki/Avro_vulcan about half way down the page, a Vulcan landing. Now the only purpose of these arms surely is to distance the plate from wing airflow and thus minimise lift loss. Such devices must, I believe, be considered air brakes. Spoilers are always hinged from the wing surface to maximise lift loss. — Preceding unsigned comment added by DesmondW (talk • contribs) 16:23, 1 November 2012‎

You have written Spoilers are always hinged from the wing surface ... Do you have an authoritative source for that idea? Our article gives a comprehensive explanation of what constitutes a spoiler (see above) and it says nothing about spoilers always being hinged. If it is true that spoilers are always hinged from the wing surface, that should be incorporated into the explanation, complete with in-line citation to identify a reliable published source.

The devices on the Avro Vulcan, and on gliders, operate in significantly different ways. The Vulcan was a transonic delta-wing aircraft. Its devices were primarily to prevent the aircraft exceeding its maximum Mach number although they could also be used to increase the rate of descent during approach and landing. At high Mach number an aircraft's lift coefficient is very low so induced drag is low, and extending these devices has little effect in spoiling lift but it increases parasite drag significantly but does not increase induced drag much. In contrast, a glider is a low-speed, high aspect ratio aircraft. Its devices are primarily to increase drag at low speed during the approach and landing. At low speed an aircraft's lift coefficient is high so induced drag is high and extending these devices has a signficant effect in spoiling lift.

The devices on the Vulcan extended significantly above the wing surface, leaving an air gap between the bottom edge of the device and the top surface of the wing. There is no similar air gap between the bottom edge of the device on a glider and the top surface of the wing, except perhaps at extreme extension. In a glider, it is rare for the pilot to fully extend the device - in a well-planned approach and landing the devices are only opened about 50% to 75% of maximum extension. At this extension, there is no air gap between the bottom edge and the top surface of the wing. Dolphin (t) 04:43, 3 November 2012 (UTC)

Your comments appreciated. --DesmondW (talk) 16:23, 1 November 2012 (UTC)

I have added an image of the open spoilers on a Slingsby Capstan. See my diff. Dolphin (t) 05:35, 30 January 2015 (UTC)

Lift dumpers & deployment

I am considering adding a section to describe the automatic deployment on landing of lift dumpers on airliners, emphasising the difference (ground deployment only) from control spoilers (airborne & possibly ground deployment). Any comments? --DesmondW (talk) 09:43, 1 November 2012 (UTC)

Good idea, especially if you have a reliable published source and can cite that source. The article is presently short of citations. Go for it! Dolphin (t) 11:32, 1 November 2012 (UTC)