Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

I read an article that claimed the P-61 Black Widow could turn as tight as the tightest turning U.S. fighter in WW II (even though with the twin engines and massive bulk it is the heaviest and biggest U.S. fighter manufactured in WW II)........the article attributed this to the spoilers in the wings.............So my question is why are we still using ailerons and not spoilers since the ailerons have a opposite yawing effect to the direction of the bank creating aileron INEFFIciency.........while the spoilers have a yawing effect that is in the same direction as the bank adding to spoiler EFFIciency. Also, the spoilers help to rotate the aircraft in the direction of the turn making the turn tighter and quicker.................so it seems that the spoilers are more efficient. How come the propeller driven aircraft manufacturers(Cessna, Piper, Beechcraft, Lockheed Hercules, etc.) continue to use ailerons instead of spoilers?????? Why????
Thanks for your valuable reply.
larrysogla

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Many airplanes are using spoilers. Many commercial airliners for example. Of course, they usually have both.

Not always.

One reason: differential ailerons
Another reason: better control of the roll axis than spoilers

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Also, design choices are often driven by other things, like consumer acceptance or maintenance considerations or manufacturing costs.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

The P-61 used spoilers because it had full span flaps. The F-14 was similar in concept

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Only the early prototypes & P-61A's had spoilers and full span flaps, all later variants had a small aileron at the wing tips and the spoiler.

Apparently the wing aileron is better flight adjustment and trim as apposed to flight control.

Having had a P-61 model with the spoilers I was very surprised at how efficient they were.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

For full scale, high wing aircraft, how is the pilot going to pre-flight inspect spoilers on top of the wing? In the end, they wouldn't. Eventually some family members would be calling lawyers instead.

I remember a bird-like glider design and build in one of the magazines that had very little vertical tail surface. To avoid severe adverse yaw when rolling, the designer used spoilers instead.

Bedford

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Here's why we don't use spoilers. They don't work in a steep bank.

http://www.youtube.com/watch?v=aRmg88t35Y0

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

http://mu-2aircraft.com/ Have spoilerons; it is also a plane that will eat your lunch if flown wrong. low speed is the problem. At slow speed you only have one small surface on one side of the wing that is acting, so if you got into a stall, turning the stick to the other side trying to keep the wings level, does nothing to help. It is like aileron differnital to an extreem. Many big jets have spoilerons to help with either adverse yaw; to get more up aileron surface at a certain deflexion, or at high speeds the ailerons become inactive and the spoilerons are used to keep the stress low and the drag low at altitude.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

I was just wondering..............since before the U.S. military improved their fighter tactics in WW II to "zoom and boom" (diving attacks and then zooming up to regain altitude to position for another diving attack or to escape at high speed)................they were old schooled in the WW I "turning and fighting" tactics. Also, since the WW II fighters of the U.S. were designed in the pre-WW II years(Corsair, P 47, P 38, P 39, P 40) and during this pre-WW II period........as we all know, the U.S. Military was adhering to the "turning and fighting" tactics.................well then how come the designers did not choose the spoilers as in the P 61................the turn was very tight with the spoilers. It seems that the designers were after some performance that has to do more with rolls and secondarily, of turning ability. Of course the British, Germans, Italians and the Japanese were also not using spoilers. Could we have had really tight turning fighters that would beat the Spitfires and Zeros for turning ability????
'Nuff said
larrysogla

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Tight turning ability usually refers to rate of turn which is all about how much G you can pull, speed, aircraft weight and maintaining energy etc. Ailerons and spoilers are all about rolling ability which is important for aerobatics but not so much for combat. (Once you have rolled into the turn you are more worried about how fast you can pitch)

Cessna Caravan uses spoilers (and ailerons).

Lockheed Hercules doesn't, but Lockheed Galaxy does.

Spoilers work well with positive G, poorly with negative G, and not at all at zero G.

Spoilers work well at transonic speed where ailerons twist the wing causing adverse roll (as opposed to adverse yaw).

Ailerons work well in other regimes and can be designed to avoid adverse yaw.

Spoilers work where you want to steal most of the trailing edge for flaps leaving little room for ailerons (a la P61 etc).

If you have spoilers they can be really handy to stop the aeroplane as well. They add drag but more importantly dump lift, which puts more weight on the wheels allowing heavier braking.

Spoilers may reduce adverse yaw but they achieve it by adding drag. It probably varies with type but using aileron and rudder may give lower overall drag (higher 'aileron efficiency') than spoilers.

Like all things in aviation it becomes a cost/efficiency/weight/complexity compromise. The outcome is that most jet transports use them, many large turbo props do too, but not many light aircraft. The specific role of a military aircraft may alter the compromise toward or away from spoilers.

I have never heard of a model using spoilers, or ailerons and spoilers together but it would be interesting to try.

Dave H

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

I was thinking about this post today. Some one should build a ugly stick with spoilers instead of allirons and see how it does.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

The sticks have symmetrical wings so they can do inverted stuff equally well. Would you consider that?

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

I'm not sure I agree with this totally. Take the case of spoilers on an Ugly Stik that is upside down. Spoilers positioned more towards the trailing edge ala P-61 and MU-2 would have some tendency to act as lift flaps in such a case so it would roll back upright.

However I'd be the first to suspect that the rolling action under the different G conditions will not be consistent. As such I agree that they are best used on airplanes that will no find themselves upside down or otherwise negatively loaded except under dire circumstances.

As modellers who can easily overbuild and over power our designs we often forget that full sized aircraft operate under very confined load and speed envelopes that we do not. The B-52 model video noted earlier along with the related Fairchild base full size B-52 crash that I found in the related videos shows what happens when you ignore or get tossed out of that envelope by circumstances. Using spoilers for roll control in model applications has some possibilities for some specific types of design but obviously it isn't something you want to use for all styles of model. As gerryndennis closed with it's about compromise and choice.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

An upside down plane with spoilers will roll, but when it is upside down it will have a large dose of adverse yaw.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

I don't know, it seems to me that we are pretty much saying the same thing? IE spoilers work better upright compared with inverted.

Sure a spoiler toward the trailing edge of the wing, especially if it has a small deflection is essentially similar to a split flap so yes, it will provide some roll effect in negative G conditions.

A spoiler near the point of maximum thickness with a 90 degree deflection, not so much.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Exactly

Dave H

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Andy Lennon discusses these in his book. He used them in a plane that had full span slotted flaps. Apparently they worked quite well and were effective inverted.
Ben

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Yup, his Crow uses "slot lip ailerons". They're actually not your usual ailerons nor the usual spoilers, however.

They're not hinged at their LEs like the usual spoiler is. These actually move completely away from the top surface of the wing to create a slot between themselves and the top of the wing.

He certainly says they're effective, but that wing is way out in design. The full span flaps are slotted flaps. They extend out and down. And those slot lip ailerons extend out and up, way up. They're so unique no wonder he didn't call them spoilers.

It really would be nice to hear from someone with a model that has regular old spoilers for roll control.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

larrysogla, gents

It really would be nice to hear from someone with a model that has regular old spoilers for roll control.

When you make a short turn there is nothing to "spoil", and especially not with the high wing!!!

I do fly the Orion of Ed Kazmirski (USA), First world champion aerobatic pattern flying 1960.
Look what he did use to win!!!.Picture 1, red square on the left side.
Picture 2 a picture of my Orion, does have some damage now so I have the possibility to show how I did make them.
My Orion is "experimental", these ailerons, Ed did use, we call "frise ailerons" there are several different examples on a lot of airplanes, only it isn't known I think.
My plane has a span of 70 ", weight is 10 pounds with an ENYA 60 4C engine and has a pneumatic retractable main gear.
The ailerons are an invention of Leslie George Frise of GB you can find a lot about this inventor on Internet..

I am changing the Orion now to accept normal airlerons to compare. The "frises" are an solution for yaw control in normal flight but not inverted.

I also do fly Horten gliders and on these planes I use drag rudders, I think we can call these reeal "spolers", they spoil energy and always one of the two is deflected, only on the low wing.
The deflection I calculate with a special controller in my transmitter.
This drag you need for flying wings sometimes is generated with split rudders (USA).

Cees

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

The Mitsubishi MU2 aircraft have full span flaps and spoilers. There is a price. On approach, corrections cause you to fall below glide slope. And when you are landiing in a crosswind, well, you get the picture.

Also, the B47, Boeing aircraft had a problem early in their dvelopement. Turn the ailerons left, and you wouldroll right. The wings were so flexible that the camber created by deflecting the aileronwould case the entire wing to warp. Boeing corrected the problem by adding spoilers and incorperated spoilers in the B52, Dash80 and everything else since. They have been favored by jet transport manufacturers ever since. Not because they turn better. But becasue they allow a very flexible wing assembly to be used without the warping issue.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Mitsubishi carried their roll control scheme over to the MU300 Diamond (BeechJet, BE400, Hawker 400). It has these very small trim tabs on the outer wings and uses almost full span spoilers for roll control. They have a fairly short chord, maybe 2-3". When doing an approach in gusty conditions, each time you have to raise a wing you effectivly do it by dropping the opposite one. So every correction you make makes the airplane lose a bit of altitude. I have heard of some guys using this to their advantage by making a series of quick, shallow roll commands to get back on glideslope without changing the power or pitch of the airplane.
Another problem is if you are very near the stall, using them to raise a wing could have adverse effects.
I couldn't find a pic of the spoilers but this pic from underneath shows the large flaps and little tabs.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

As many have said the MU-2 and the beachjet aka. mitsu diamond, hawker 400 use spoilers for primary roll control. I have even seen a Piper Seneca that was outfitted with spoilers instesad of ailerons. There is a downfall to this. The Beechjet used this because if they put ailerons on it it would not have enough room to carry an acceptable fuel load. There are tradeoffs for everything in aviation. What I think is missing in this conversation is the airplanes manners in the event of an engine failure particularly on take off. The MU-2 has a terrible safty record becuase when you loose an engine and try to keep the wings level using roll controll not only have you lost a ton of thrust, but now you are trying to level the wings by destroying lift on one of your wings. I think Mitsu's were used the spoilers to get more fuel into their wings, but ailerons are a more effecient way of creating roll.

Something I had not thought of before is the concept of spoilers on an aircraft that is inverted. It seems that reguardless of which side is up that the spoiler would still kill the lift on the side that is extended. So in theory a spoiler only airplane would get really interesting as it approached the 90 deg bank angle. What would cause the spoiled wing to climb rotate past 90 degrees to the inverted orientation? I know there are many variables that I'm not touching.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

Archie League, beenie, and ndb8fxe,

I know you have to be wee bit cautious of the manufacturers word, but I doubt the FAA would let them spin things too much. Check out the MU 2 web site given above. This 'phenomenon' is addressed under 'myths'. Deploy a spoiler and one wing has more lift than the other so the aircraft rolls around it's longitudinal axis (i.e. the wing with more lift goes up), exactly the same as when you use ailerons. Essentially any aircraft that makes several rapid roll inputs will lose performance (in this case 'a bit of altitude' ) all else being equal. The first time I saw this effect was when my (full size) helicopter instructor started gently stirring the stick (collective) while we were in a low hover. Without changing power we touched down, he then held the stick still and we lifted back in to the hover, again without changing power. The lesson was that a smooth pilot can pick up more women.... I mean weight.

Again this addressed in the web site above. Firstly, the MU 2's safety record is significantly better than comparable aircraft. Secondly, engine failure accidents they have had are due to training failure, i.e. pilot error. Probably because this type of aircraft tends to be flown by less experienced pilot.

The primary effect of engine failure is yaw, and therefore the correct control input is rudder not aileron (or roll spoiler). In fact once the correct rudder input has been made most aircraft require very little or no aileron input.

In any case he MU 2 is certified in exactly the same way as all other aircraft and will therefore perform as intended following an engine failure with whatever amount of reduced thrust and increased drag the aircraft has, providing it is flown correctly (part of this certification procedure requires that an average pilot can achieve the required performance so it shouldn't be any harder to fly than any other plane)

This quote got me thinking some more. At moderate AOA's the pressure on the bottom of the wing is also slightly lower than static ('high pressure' is relative, it is certainly higher than the pressure above) so therefore it could be spoiled during negative G manouevering. So yes I think we all agree that spoilers would have some effect in negative G but I still reckon ailerons would work way better.

Easy, stay positive G then spoilers would work just as well as when wings level. Bank angle has nothing to do with G, elevator controls that. But yes the point you were making was that things would get interesting as you approach zero G and go through to negative.

Does any one know any F-111 pilots? IIRC the F-111 has no ailerons and only has spoilers for roll control. I don't know how or if it flies in low or negative G.

Dave H

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

In your helicopter, use the pedals like you did with the cyclic and it will do the same thing.

RE: Wing spoilers vs. ailerons??P-61 Black Widow had spoilers....
 

"The first time I saw this effect was when my (full size) helicopter instructor started gently stirring the stick (collective) while we were in a low hover."

The cyclic is the 'stir-able' stick. And on older Bells (recip and turbine) you can stir the heck out of it (delayed response) without causing any change of roll/pitch movement. The collective is the 'power' stick and moves up and down only.

Terry in LP