I am about to fly a plane that has a outboard augmentation roll spoiler on each side of the wing that also doubles as a flight spoiler. When the left aileron moves up the spoiler on the left side of the wing moves with it. At this time the aileron on the right side moves down as normal and the spoilers on the right side remain flush. This movement is exact and mirrored when in a right hand turn.
When closed the outer spoiler moves with the aileron minimally, at full aileron spoiler raises about 3/16 off a inch. The spoiler moves at the same time as the aileron. Some real aircraft have a delay in the spoiler movement while others do not. Position of the spoiler panel in relation to the center of lift and and relation and distance between itself and the aileron all are critical I'm sure to it's effectiveness and aerodynamic behavior. Obviously this entire project is experimental as I do not have a wind tunnel or tecnical info, which by the way Boeing will not give out to anyone, concerning the arrangement of how all this works.
So , here is my question. Has anyone ever built a wing using a device like this and have any info as to it's effect or characteristics. I don't mind the theorectical imput, but what I'm looking for is the actual experiance and conclusions that someone came to while using such a device in actual model practice. My biggest concern is the seperation of the boundary layer as the spoiler rises which can cause a great loss of lift resulting in excessive roll rate with obvious results. Dean

I was thinking of trying something like that, only on the bottom, to keep the airflow on the top good.
Haven't gotten up the enthusiasm to try it yet.
Gliders tend to have spoilers at the high point and deploy them symmetrically.
Fighters: Cougar, Phantom, tend to have manuvering spoilers just ahead of the ailerons.

As a general rule of thumb I would think the aircraft makers don't give out data, the data and etc. are not magic or anything they want to keep secret, it just makes life easier for them to not to have to respond to those kinds of questions.

I don't know if this counts as my building anything but I have been involved with wind tunnel tests of several fighters that used spoilers (the model shop made the models for us, a good way to work). I am a safe person to have seen the data as I have forgotten most of it! Old age brings with it wisdom (sometimes) and forgetfulness (fairly often).

As Tall Paul said they are usually put on a wing station just ahead of the hinge line of the ailerons. Most things in life are a compromise and this tends to be one of them. Although they might be effective at other stations they certainly are effective enough at that location, It is used by everyone so you might as well go with it.

At low deflections you can think of them as an aileron that just goes up. Of course the flow separates but it is no big thing. I think the delay in spoiler movement you mentioned is due to that the initial control is input with ailerons for small precise moments and minimal aero disturbance (you will get some of course). As you need more you bring in the spoilers to get more rolling moment. The drag goes up and other stuff happens but you usually need the roll more than the side effects. I remember sitting at the window seat on an airliner and watching the movements of the various stuff during flight and landings maneuvers. Very educational.

It would be interesting to see the layout of the wing as to precise locations that you use.

A good drawing or plastic model of a Boeing airplane would give you a layout of the spoilers and ailerons. It may be on the net.

The whole purpose of a spoiler is to "spoil" the flow. So, if functional, the spoiler kills the lift on the wing that it is on (or at least the spoiled portion of that wing). The side effet is to increase the drag.

So, your question doesn't make sense... the spoiler's purpose is to kill the lift by disrupting the flow. The increased drag on that side results in proverse yaw.

Obviously it will spoil lift, it was the idea of " excessive lift "loss that I was concerned about. I tried to put a basic photo attachment of the wing in question for everyopne to see but this forum is so limited in what it will receive. It's very frustrating as the photo was a simple scanned 3 X 5 snap shot in my Epson scanner. Maybe I'm doing somthing wrong. Actually photo of the wing appears in high lift section of Rc universe...wish I could send it here..Oh Mr. moderator can you help me?

An historical note on use of spoilers...
Any decent model of the Northrop P-61 will have the spoilers this plane had.
Top and bottom.
In flight testing, the airplane was lost, and the pilot almost killed.
No spoilers were ever used on the P-61 after that; although they were installed, they were disabled.
On the short version of the Tristar, the -500, the plane demonstrated a tendency to tighten a turn. Without the use of spoilers this rapidly became an uncontrollable situation! I've seen the pilot with the column hard against the instrument panel, and the turn -still- tightening.
Pulling the spoilers slowed the plane and pitched it up. The CAA made a mod to the autopilot that -automatically- extended the spoilers on CAA certified planes above about .86 Mach.

Andy Lennon's book gives the NACA results of a bunch of tests on these layouts. ("The Basics of R/C Model Aircraft Design")

The general rule is that (roll control) spoilers should be 10% of the chord, and located at 70% or further back from the leading edge, and about 60% of the semi-span. (WITH ailerons, the span would be split between the two)

There's a page in the book that shows the graphical layout of these and other devices, on a variety of wing shapes... plank, tapered, swept, etc.

I hesitate to publish the graphic on a public forum without asking Andy, but if you like, email me and I will scan it and email it to you. (3 pertinent pages, scanned at a readable size, is 500k)

Spoilers used over the slot lip ("slot lip ailerons") are even more effective (when the slotted flaps are deployed) because the opening spoiler also opens the flap's slot, dumping the flap's lift. (like a Boeing airliner)

In general terms spoilers were initally used since the conventional ailerons on high speed a/c caused wing bending and an adverse roll.

Fighters such as the F9F and F11F had only spoilers for roll control. They actually called them flaperons. Those two a/c did not roll about the longitudinal centerline because of the spoilers.
The FJ4 had midspan ailerons but to increase the roll rate a lower altitude and high mach numbers they added some flap mounted spoilers on the FJ4B.

Boeing airliners like the 707,720, and 737 have inboard , outboard, and ground spoilers. The flight spoilers aided roll control at all times. They also could be deployed on both sides simultaneously as speed brakes. All the spoilers are raised upon landing to aid in stopping. The aircraft also have inboard and outboard ailerons. The small inboard ailerons are in use at all times but the outboard ailerons are only used when the trailing edge flaps are extended greater than 15 degrees.

Yes to aid in stopping.... more specifically to dump the entire lift on the wing to make the brakes more effective. Dean

In actual practice the spoilers greatly increased the drag which aided in slowing the a/c. Almost all airliners today are equipped with autospoilers. There is a landing weight penalty if the autospoilers are inoperative.The brakes were normally used below 100 knots and by that time the wing was already stalled.

Dean, it seems that you are doing this on a particualr airplane, maybe a scale one, while finding ways not to tell us what plane it is for. C'mon buddy, spill the beans. THen we'll all have a better handle on what you are talking about.

As for having too much roll control - isn't that what dual rates are for? Actually, if you are worried about a sudden Roll response, here is a general rule of thumb for spoilers:

The farther aft the spoiler is hinged, the more proportianal and moderate the response will be. THe farther forward the spoiler is, up the the max-thickness point, the more sudden and dramatic the response will be. This is because forward spoilers affect all the wing area behind them, from the instant the spoiler is raised just a bit. Aft spoilers affect less wing area and depend on added drag and changing airflow around the wing ( like a split flap) for their effect.

Photo of wing is at http//homepage.mac.com/mikejames/rcu_flaps_site/index.html . It's the Easttern airlines model

Forgot to mention it's in the contributors page. DEan

OK, I see what you are doing. If that's the amount of spoiler travel that you intend to have in the air, I wouln't be surprised if you didn't see a difference. That's a small amount. You would probably see more effect when the flaps are down.

Being that the spoilers are inboard and don't move very much, it should be no big deal. You could start there and increase the mix ratio for aileron-> spoiler and see the difference.

I have used spoilers berfore, but not for roll control.

BTW - Mike: On your Henzil Browne page, the first slat sketch was actually drawn and posted by me

JohnG,

Oops. Sorry John. I've fixed that to credit you.

No biggie. Just something I noticed.