Ammount of available control surface mov

I have recently been watching the video made by members of the Glue Dobbers. In one segment it is easy to see the small amount of elevator and flap movement during maneuvers. In the past I have heard the opinion that this shows " it is evident how little input is needed to preform changes in direction". I am now wondering if this line of thought is correct. Could it be that what we are seeing is how little flap or elevator movement is possible during flight? We generally try for somewhere around 45 degrees of up and down( Ok, for sure, sometimes less) on the building board, but the video plainly shows that this is way less than is needed (or alowed) during the pattern.I have asked several friends that fly combat and other events and they use very little elevator throw than we do in stunt, perhaps a little as 10 degrees or so. Could it be that the input at the flyers handle is much more than air pressure allows on the actual flap or elevator? Has anyone ever tried less movement? Please try to keep your answers as simple as possible so that rank novices like myelf can understand.THANK YOU!
Joe

On my Pathfinder profile it only has 18 degrees up and 18 degrees down on the flaps and 20 degrees up and 20 degrees down on the elevator and it does very tight square corners.

Stunters are generally setup with excess (Emergency) turn, while combat models are adjusted so that they turn tight but don't slow down. Slowing down a combat model is just asking to lose the match. Combat models are also setup with more aft CG, which requires less elevator to turn a given size, less drag, etc. This does lose some accuracy, but it's a trade-off, hopefully made up for by pilot skill. Steve

I've become quite comfortable with 20 degrees either way. I suspect, and have had one airplane where I could demonstrate it, that excess deflection (a little over 45 degrees) would cause the stab to stall, loose lift, and widen, not tighten, the turn. I think the idea of "emergency" turn has to be approached very carefully or just the opposite will result.

I believe it has been demonstrated that anything over 30 degrees will definitely produce more drag than additional lift. Matt's current plane, as I recall, uses about 8 degrees or so of maximum flap and maybe 15 or 16 degrees of elevator. And, yes, it does sharp corners. We had in the past set up planes with 30 degrees in each direction, and still kind of shoot for that, but then we adjust it out at the handle. You might be surprised with a well trimmed plane as to how little control movement you do give it.

But definitely do not go over thirty degrees when setting up your controls. You will find that the controls will be too fast and the plane will end up being jumpy. Not good.

I generally have 40 degrees in all my built ups. Simply because I mount the bellcrank the same in all my models and it has the same amount of travel every time. How many degrees you can get in your control system has nothing to do with the jumpyness(is that a word) of your model. Setup of the control system as far as where you drill the bellcrank and the horn holes sets the speed and deflaction rate. The overal amount of throw on the bench really means nothing in the air. I have heard as little as 13 degrees. I keep hearing the term extra insurance deflecfction. I think there is no way you can actaully deflect your models flaps and elevators to the full 40 or 45 degrees. Netzeband Wall comes in way before that and the stall rate would happan long before 40 degrees. Mine goes that for so I use it to setup the equal amounts on the bench. 40 up and 40 down gets me the pretty even turn each way that I am looking for. If it is 46 up and 34 down then it might be a bit uneven in the air. So I move the rod until I get it going the same on each direction.

Leonard you said Matt uses 8 degrees. How did you figure this out? How were you able to make in flight measurements of the surface deflection?

>Leonard you said Matt uses 8 degrees. How did you figure
>this out? How were you able to make in flight measurements
>of the surface deflection?

We found out that on this plane he need a lot more elevator than flap. (Or, to put it another way, he needed a lot less flap movement than elevator. The flaps are full span flaps, by the way, and the elevator throw is made adjustable). We had to take the elevator throw almost to the limit on this plane the way it was set up. Then, after narrowing the spacing on the handle to where Matt was most comfortable with the set up, and after fully trimming it out and a few weeks of flying, we took a special made protractor and held it alongside the fuselage of both the elevator and flap and I watched while Matt gave full deflection, as when he pops a corner. And...that was the result. Far less flap than I had imagined. Even less elevator than I had thought would be needed. It is a thick airfoil and he does have the cg back pretty far, but it is quite stable.

Leonard,

I am uneasy with the thought that Matt may set up his Mustang for less than 30 degrees of flap and elevator travel. The Mustang III is intentionally designed with a higher wing loading than Matt may be used to. If he sets it up like his Stuka, I don't think he will like the airplane. It is designed to fly nose heavy. Nose heavy airplanes are very stable with good, easy tracking rounds. It takes a lot of elevator to turn a stable airplane. It also takes a lot of flap deflection to provide the necessary lift for sharp corners. If Matt builds a 57 oz airplane and sets the controls up slow and expects to be able to fly like his Stuka, it won't happen. Slow controls and an aft CG will cause the airplane to stall buffet in corners from insufficient lift. The Classic airplane used a 3" bellcrank with a 15/16" throw (Top Flite nylon) and 1" horns which will give 40 degrees on the bench. I use 4" bellcranks now but they are custom made to provide about the same ratio of bellcrank width to the operating arm length, or, 4' width and 1 1/4" throw. Generally, my airplanes require large control deflections both to turn a stable airplane and to provide the necessary lift for a tight corner. It is a problem when people apply their own ideas to a design without understanding the reasons for the various features of that design. If people "do it their way" they shouldn't be supprised if their copy doesn't fly as well as the designer's. If Matt installed a 4" bellcrank with 3/4" operating arm, I think he is going to be very unhappy with the airplane. It is likely to have a slow buffeting turn.

To understand the logic of my designs, it might be helpful to check out my last post on wing design. It applies to the Mustang III.

>Leonard,
>
>I am uneasy with the thought that Matt may set up his
>Mustang for less than 30 degrees of flap and elevator
>travel. The Mustang III is intentionally designed with a
>higher wing loading than Matt may be used to. If he sets it
>up like his Stuka, I don't think he will like the airplane.
>It is designed to fly nose heavy. Nose heavy airplanes are
>very stable with good, easy tracking rounds. It takes a lot
>of elevator to turn a stable airplane. It also takes a lot
>of flap deflection to provide the necessary lift for sharp
>corners. If Matt builds a 57 oz airplane and sets the
>controls up slow and expects to be able to fly like his
>Stuka, it won't happen. Slow controls and an aft CG will
>cause the airplane to stall buffet in corners from
>insufficient lift. The Classic airplane used a 3" bellcrank
>with a 15/16" throw (Top Flite nylon) and 1" horns which
>will give 40 degrees on the bench. I use 4" bellcranks now
>but they are custom made to provide about the same ratio of
>bellcrank width to the operating arm length, or, 4' width
>and 1 1/4" throw. Generally, my airplanes require large
>control deflections both to turn a stable airplane and to
>provide the necessary lift for a tight corner. It is a
>problem when people apply their own ideas to a design
>without understanding the reasons for the various features
>of that design. If people "do it their way" they shouldn't
>be supprised if their copy doesn't fly as well as the
>designer's. If Matt installed a 4" bellcrank with 3/4"
>operating arm, I think he is going to be very unhappy with
>the airplane. It is likely to have a slow buffeting turn.
>
>To understand the logic of my designs, it might be helpful
>to check out my last post on wing design. It applies to the
>Mustang III.
>
>Al

No problem here, Al. Matt understands the design concept of your airplane and is following it pretty much to the letter. This is a classic airplane, after all, and one should build it as the designer intended. If I remember, correctly, he has close to 35 degrees of deflection each way on the flaps and has an adjustable elevator throw "just in case" (with 4 inch carbon fiber belcrank, carbon pushrod that is also adjustable, and ball links on the controls).

As has been pointed out, any excess amount of deflection can be "dialed out" at the handle. In the end you set the amount of deflection by the spacing on the handle. His spacing is quite narrow on his Stuka but could well be considerably wider on this one.

The Mustang is also coming out nose heavy following your design, but, as you state above, that is as designed. Here is a recent picture of the progress. It weighs 45 ounces as shown, which includes the engine, interior, sprung gear and wheels, but does not include the muffler, prop, or finish.

Its gonna be a beauty.

Leonard, tell Matt to be sure to make the wing fillets from light weight, hollowed balsa. Large fillets from any type of filler will weigh a ton. The tail fillets should be built up from thin sheet. The shape of the wooden wing fillet is shown on the magazine Mustang plans or I can send him a template. I just remembered. the fillets are covered in Matts Millennium videos.

Also, Matt should align both wheels to point into the circle, or more specifically, to allow the airplane to roll, on takeoff with the nose pointed slightly out at release. The adjustment with shock gear is easily accomplished with a soldering iron on the airplane. If Matt has questions, have him give me a call.

>I believe it has been demonstrated that anything over 30
>degrees will definitely produce more drag than additional
>lift. Matt's current plane, as I recall, uses about 8
>degrees or so of maximum flap and maybe 15 or 16 degrees of
>elevator. And, yes, it does sharp corners. We had in the
>past set up planes with 30 degrees in each direction, and
>still kind of shoot for that, but then we adjust it out at
>the handle. You might be surprised with a well trimmed
>plane as to how little control movement you do give it.
>
>But definitely do not go over thirty degrees when setting up
>your controls. You will find that the controls will be too
>fast and the plane will end up being jumpy. Not good.

Of course, just in case someone might misunderstand this, it means to slwo the controls down so you get +- 30 or so with full handle movement. Setting it up with the same fast rates and just limiting the motion by allowing it to bind somewhere isn't the right way to get reduced movement.

For the record, my controls can actually be moved well over 45 degrees in either direction. But there's no way I could actually get that much with the handle hooked up unless I broke my arm! It's slow enough it won't move that far.

Initial flights on mine were done with the flaps made inoperative purely to get the elevator response I was comfortable with. This ended up at +-17 degrees. Flap travel was then gradually dialed in until all traces of a stall on any corner had disappeared. Flap travel ended up at +-5 degrees. The surprise was that this small amount of flap must have at least doubled the effort needed at the handle.

If your airplane turns well and buffet free with only 5 degrees of flap, then your wing is much larger than it had to be. We know that flapless airplanes can also turn well without stalling. Your airplanes is simply approaching the flapless condition. Flap operation is desirable. It is pointless to put flaps on a wing which is big enough to not need them. Flapless airplanes and airplanes which use minimum flap have to reach a higher angle of attack in each pitching maneuver than airplanes where lift comes from the flap deflected airfoil to get the necessary lift. Competitive appearing maneuvers are enhanced by the use of flap deflection to minimize the change of pitch attitude in each maneuver. Airplanes with little or no flap have to initially pitch beyond the new desired track and then to reduce that pitch attitude as the corner is completed. Airplanes with effective flaps are able to exit corners with less apparent fuselage pitching. You have only proved that flapless, or near flapless airplanes are also capable of flying the pattern. It says nothing of the appearance of the corners. Airplanes with too little wing loading usually exhibit many undesirable characteristics if the point is to make competition smooth corners and have the ability to compete in less than calm winds.

I have found that MY airplanes handle better with controls sized for 1 to 1 ratio of elevator/flap movement. I have tried adjustable controls, but kept coming back to 1 to 1. Adjustable ratios encourage the use of oversize wings by allowing the flap deflections to be reduced. I prefer to use tail volume coefficient to design tail surfaces appropriate to the airplane and avoid the need for adjustments which change ratio.

>I have found that MY airplanes handle better with controls
>sized for 1 to 1 ratio of elevator/flap movement. I have
>tried adjustable controls, but kept coming back to 1 to 1.
>Adjustable ratios encourage the use of oversize wings by
>allowing the flap deflections to be reduced. I prefer to
>use tail volume coefficient to design tail surfaces
>appropriate to the airplane and avoid the need for
>adjustments which change ratio.
>
>Al

You said a mouthful there. I have tried moving around also and always ended up going back to 1:1. Once I even changed motors to get the CG right so the 1:1 would work instead of having to dial in all the extra elevator to get the response I was looking for. For some reason 1:1 is always a very good solid repeatable feel. Not to mention very easy to setup.

You are right the big flap deflection helps create a sharp corner or the illusion of one. The flapless will fly the pattern real good but it tends to look more rounded in the corners.

OK, a lot of this has been very educational, but would somebody please answer my basic question! To witt: Even if we set the throw on the ground at let us say 45 adegres is that limited in the air by air pressure as the video from the Glue Dobbers seems to indicate?

>OK, a lot of this has been very educational, but would
>somebody please answer my basic question! To witt: Even if
>we set the throw on the ground at let us say 45 adegres is
>that limited in the air by air pressure as the video from
>the Glue Dobbers seems to indicate?

I have a flapless plane (original design) that I can give 90 degrees of deflection to each way. It does the "Whingding" as I call it. A full stall spin on the lines. I can do about eight or nine of these from a 45 degree height before I have to straighten things out--hopefully while it is pointing up, not down.

But too much deflection will lead to a stall. More drag than lift.

>>>But too much deflection will lead to a stall<<<

I am not so sure.

No. (reply to 15.)
Al

Elevator deflection, perhaps not, but throw in flaps...

Isn't this what people refer to as the "Netzeband Wall"?

>OK, a lot of this has been very educational, but would
>somebody please answer my basic question! To witt: Even if
>we set the throw on the ground at let us say 45 adegres is
>that limited in the air by air pressure as the video from
>the Glue Dobbers seems to indicate?

Probably not. This is referred to as the Nezteband Wall - where the line tension difference required to deflect the controls equals the line tension. You can tell if this is the case of the model is hanging on one line. Most stunt planes these days, trimmed the way most people trim, don't have this problem.

The travel is usually limited by the pilot's input. I could deflect my controls far more than I usually do - because if I used more deflection I wouldn't be able to reliably come out of the corners in the right direction. This is the real limitation on turn radius - not the technical capabilities of the airplane.

I am not convinced that the very small in-flight deflections are really as small as most people think. I have a lot of reflex/nerve problems, and I have a lot trouble with some aspects of following motion. But I do seem to be blessed to some degree with the ability to see "snapshots" of airplanes in motion. I can very frequently see the control deflection in the middle of corners when watching patterns. I frequently see what appears to be some very significant angles. I don't have a way of measuring it, but I estimate that Ted and David frequently get up around 25-30 degrees of deflection in the maneuvers. I think I am close to the same most of the time.

From post #10 by Al Rabe (sheesh, how did it get all the way down here?)
>You have only proved that
>flapless, or near flapless airplanes are also capable of
>flying the pattern. It says nothing of the appearance of
>the corners.
With respect and much doffing of cap I have to disagree. Well before I even started trimming it (it would free flight on the overhead part of the hourglass for instance) it was good enough to have me leading for a while in the Victorian (Australia) state championships. The judges were heard to comment on how sharp and clean the corners were. Maybe I should point out though that the flaps were a continuation of the airfoil and averaged about 3/4" thick at the hinge line and the tail moment (hinge to hinge) was 21.5". Let's just say it worked for me

Here is the first corner of the hour glass captured from the in-flight video, I stepped through the frames and captured the frame that showed the most elevator deflection. Then set the TwistMaster on the bench, duplicated the angle by viewing the elevator from the cameras view point and measured the angle. It is about 18 degrees.

Aah. The "scientific approach," albeit from our own "Mad Scientist Working for Good, Not Evil." Good stuff there. Bob (or MSWfGNE), was that the max amount of "up" you could have given it, or was there more deflection that could have been used?

The TwistMaster has about 25 deg. up/down, a little less than I normally set my stunt ships for. I try to get at least 30 but the flap hinge lines are so tight that it stops at about 25.

When this video was shot the airplane had a Saito 40 FS on the nose, it was flight trimmed with a Saito 30 and I didn't add any tail weight to make up for the heaver engine. It was also carrying 6 ounces of video equipment and even with all that it still only took 18 deg of movement to make a tight corner. I would imagine a well trimmed stunt ship would take somewhat less...

Nice picture Bob. I like it .

I guess it is relatively small model and loaded by that equipment. I want to say that the radius of corner is relatively large in relation to the tail length.

I have an analyze of two models. One is large .61 model and second is smaller for .26-.30 engine. They are of very similar design if we speak about area and deflection ratios. That large needs 29.5 deg, that smaller one needs only 23 deg for the same radius (3.5m ~= 12ft?), in the same "programmed" conditions.

So if your model carry heavy equipment and radius little larger than "empty" weight, then it does not surprise me you are at or under 20deg. But I am not surprised with Brett’s estimation of up to 30 deg on large long tail model.

However I do not think that "better" model will need less deflection. I would say that the better or larger model will "last" more deflection.