RC newbie aileron control question
 

Im drawing up plans for my first RC airplane model right now. All other questions nonwithstanding, can anybody suggest a good method of controlling the ailerons? I am hoping to have one servo move both the ailerons (of course one up, one down) and jsut cant seem to figure anything out. The wing will be made of covered balsa wood, and as such will be hollow.

Any suggestions would be much appreciated, and drawings or plans would be even more so.

Thanks,
John

RC newbie aileron control question
 

If you are not aware of any of the many ways modellers over that years have used to control ailerons from a single servo are you sure you aren't biting too much off trying to design your own plane ? If you visit any hobby shop or model club you will see many, many models with a single servo controlling the ailerons e.g. every ARTF trainer I've ever met.

Perhaps you might want to do a little more research, build a kit or two, look at some of the thousands of existing plans before you start designing your own.

Steve

RC newbie aileron control question
 

I have to agree with Steve here.

This is probably about the easiest part of designing a plane. But, here's a crude sketch of how it's usually done.

RC newbie aileron control question
 

Thank you for the sketch DBcherry, but I know how to hook it to the servo, its the control rod - aileron connection that I cant figure out. In particular I'm looking for a method absent of wire/pulleys, and also internal to the wing structure. I KNOW that this has to be really, really simple and that I'm going to hit myself in the head repeatedly once I figure it out. As to the rest of the comments, I'm trying to do this without help in general, as I'm doing this mostly as a personal learning experience. With that in mind, I dont plan on looking at other designs or joining a club until after I have a plane built.

The rest of plane is pretty much done (on paper anyways) and I'd like to get everything finalized before I start cutting. If it crashes right of the bat, throwing splinters of wood everywhere...so be it :)

Thanks,
John

RC newbie aileron control question
 

In that case, you'll figure it out...

Hint: It's called a torsion rod. Or a control horn. Or whatever new thing you invent. :rolleyes:

RC newbie aileron control question
 

Here's one method:

RC newbie aileron control question
 

And here's another:

RC newbie aileron control question
 

gard.

the simplest method is that which minnflyer has shown,

it works and is probly the most common form for control of the ailerons from a single servo.

there are other methods , but no matter which method, control cannot be achieved without some form of wire ,cable or other mechanical device either attached to or in the wing .

it can be as simple as a single point connection from wing to aileron or a little more and in my opinion a better method is a servo installed in the wing for each aileron.

Highlander

RC newbie aileron control question
 

Thanks Minnflyer, thats exactly what I needed to see. As I suspected, I wasnt thinking about it the right way.

By no pulleys/wires I meant the linkages I have seen in a few real airplanes, with steel cable running along a pulley system to reach the aileron.

I would use one servo for each wing, but I wouldnt have enough servos if I did. (I got the radio, servos, and engine from a relative who had them sitting around)

Thanks again,
John

RC newbie aileron control question
 

If the radio you have was sitting around before 1991, please have it checked out by someone who knows RC radios. The rules regarding frequencies have changed since then.

RC newbie aileron control question
 

Also, please don't try flying it around anyone or anything. I realize you don't want help, but don't kill someone else because you were trying to fly something that maybe shouldn't have been flown or was set up wrong or one of the thousands of other reasons planes come crashing down when people don't get the propper training.

RC newbie aileron control question
 

Taildraggin: Thanks for the info, I don;t know when the radio was made so I'll be sure to have someone take a look at it.

Flyboy: I mostly want to build it myself (including making all the associated parts from scratch, cept for engine, radio equipment), I'll have somebody knowledgable look over it and help me start flying. Theoretically, the plane will work just fine (embarrisingly enough, im a 3rd year Aero Engineer) but I can already tell that the controls are going to be real sensitive. That nonwithstanding, there wont be anymore people or buildings for well over a mile from where I plan to fly it at. (with the exception of above said friend and an ATV).

RC newbie aileron control question
 

gard,

take a look here and click on the items under "Control Linkages" to get an idea of what you will need:

http://www.towerhobbies.com/listings/cat-cat-q.html

RC newbie aileron control question
 

No reason you can't make it fly, I just see a lot of kids that will not get any help for whatever reason and have seen people get hurt because of it. I was the same way when I got my first helicopter, so anxious to get it up, I took it in the back yard, started it up, and lost part of a finger. Just don't want to see someone do the same thing. Hope they can learn from my dumb move. If someone 25 years ago would have told me I would be giving advice on safety, I would have said they were nuts because I was first to try anything. I guess its better to be lucky than good, but I just hate seeing people do things I know the outcome of because I have seen it. That was my only concern.

RC newbie aileron control question
 

Oh, Oh! Ever hear the phrase, a little knowledge is a dangerous thing?

I've seen some planes designed by Aeronautical Engineering students at competitions. Also seen how completely unstable they were. One small piece of advice, drawn from the one thing that generally kills these designs; research the "Center of Gravity" used in RC planes and use it! :rolleyes: (Don't use the tail surfaces as a source of lift. ;) )

Dennis-

RC newbie aileron control question
 

Yep, sounds like me :)


I wasnt going to figure in the tail anyways, just because I wasnt planning on taking the trouble to make it a true airfoil. I looked around a bit, and all the RC models I could find used the quarter chord as the location for COG, which is exactly where I expected it to be. I'll probably place the cg a little bit farther back than that, just because I rather have it stall than take a noser, and then adjust after it actually starts flying.

On a different note, how often do you use the rudder when landing? And how helpful do you find it to have steerable landing gear?

Thanks,
John

RC newbie aileron control question
 

I suspect you'll get a lot of different answers on this one, but with a taildragger high-wing trainer and a novice pilot the rudder and steerable tail wheel are extremely useful on the ground and for approaches, especially if there is any crosswind whatsoever.

RC newbie aileron control question
 

John,

What you will find out is that as air speed decreases on landing , the ailerons will no longer be a valid control surface and the plane will rely upon the rudder for control.

the same is true in takeoffs , the rudder not only controls the plane when the the tail wheel is in contact with the ground , but as the plane leaves the ground it is also used to compensate for torque, which is produced by the engine , not so much with a vertically mounted engine but with a horizontally mounted engine torque can be extreme, and has ruined many flyers days very early.

Highlander

RC newbie aileron control question
 

Good luck with your endevour, but I'd love to see pictures before AND after your first flight.

RC newbie aileron control question
 

John,
This is what I was talking about. START with the CG at 25% of chord. Then, if it's plenty stable and you want better aerobatics, move it back a 1/4" at a time.

There's a saying in RC; a nose heavy airplane may fly poorly, but a tail heavy plane flys once.

Nose heavy will not cause the plane to "take a noser". And if the CG is just a bit too far aft the plane will be "squirelly" at best, and completely unstable at worst.

You will most definitely want rudder. For take offs and landings.

Good Luck,
Dennis-

RC newbie aileron control question
 

Wasnt even thinking about NOT including a rudder. What I was wondering was about a steerable tail wheel. It soudns like a rudder comes in very handy during landing (which I suspected) which means having the tail wheel directly connected to the rudder sounds like a bad idea. (IE, using the rudder to land, and then having the tail wheel hit the ground at an angle doesnt sound like a good idea). I was thinking about one of three options here.
1. having the tail wheel linked to the rudder
2. having the tail wheel locked into position with the centerline of the plane
3. have the tail wheel fit in a sleeve, so that it disconnects from the rudder after takeoff, reconnects upon contact with the ground. The sleeve would have two triangular slits cut in it, so that when the wheel fully reconnects it will be automatically reoriented with the centerline.

So thats why I was asking how important the rudder was to landing.

Thanks for the advice DBCherry, I'll leave it at the quarter chord then.

I'll put before and after pictures up, but dont expect them for awhile...I wont be able to start building till 2nd week of June or so. (besides, the after photo will probably consist mostly of splinters)

Thanks,
John

RC newbie aileron control question
 

In actuality , the tail wheel (to be steerable is attached directly to the rudder.

Highlander

RC newbie aileron control question
 

I will assume you are building an avarage size airplane, say about .40 engine size, or roughly 5 foot wing span with a 12 inch wing chord. On a plane of this size or smaller, you will not hurt anything by linking the tailwheel directly to the rudder. I will not ruin any of the fun for you by telling you the best way to accomplish this, but that is your best option. By the way, if you are landing with enough deflection on the rudder to cause a problem, your tailwheel is the least of your worries.

RC newbie aileron control question
 

this may help

RC newbie aileron control question
 

Hi gard,

I'm a young engineer as well (mechanical, graduated 2 years ago) and although I understand your desire to do an original design without being influenced by existing designs, I really think you're better off not doing it that way. There is no shame in learning and copying from existing designs and really the fastest way to learn is to reverse engineer other designs, see what and why they did it that way and then finding a way to improve it if possible. This is exactly what engineers in industry do all the time since no one wants to reinvent the wheel.

As for your questions about rudder and linked tailwheels: I use rudder very often on landings. I often sideslip my planes in at a steep descent angle instead of making long, shallow, power-on approaches. You also need rudder to land in a crosswind and rudder is better at making small heading changes to line up with the runway than ailerons. In all cases, the airplane is always straightened out and the rudder and ailerons are neutralized a few seconds before touchdown. All my planes are set up with the tailwheel bracket mounted to the fuselage and its steering arm connected to the rudder. This prevents stresses to the rudder hinges when landing forces on the tailwheel are applied. Some model and full scale planes have free castoring tailwheels and they rely on prop blast on the rudder to steer, but the steering control is nowhere near as responsive or positive as a rudder linked tailwheel, IMO.