Servos integral to surfaces?

On 18 Mar 2006 13:20:42 -0800, snipped-for-privacy@toast.net wrote in :

You're going to have to do a technical drawing to show what you mean.

One way or the other, the servo needs to be attached to two surfaces (one stationary, one moving) in order to move one with respect to the other.

I can think of various ways to do this. None of them seem possible, simple, or attractive to me.

Marty

Would there be some way of adjusting the mechanical advantage as you can do now by selecting different holes on the servo arm and the control horn?

Marty,

I know of no way to show a technical drawing on this usenet. I believe they discourage posting of images here.

Let me see if I can describe one surface to surface servo mechanism. It's nothing you nor I could do, but requires a complete new design by an electronic-mechanical engineer.

The servo should look something this: It would be tapered to the thinness of the trailing edge and the axis of the servo arm would be at the hinge point between the two surfaces, one fixed, the other moving. The servo would be attached to the fixed surface on the trailing edge. The servo arm would be attached to the moving part.

Of course the trailing will have to be reenforced as not to weaken the wing or stab.

It wasn't meant to be easy. The idea was meant to plant the seed of innovation, hoping someone with the know how may come forth to design or invent a new type of servo and make our hobby better (?)

Do you find the descriptions sufficient? Suggestions?

Wan

Poxy,

Sorry to be back so soon. When you read my last post, you would see that there would not be any control horn. The good thing about this design was to eliminate (if possible) linkages that lead to sloppiness of the moving surfaces. Mechanical advantage may have to be designed in. This, I leave to the experts.

Wan

I see. So you have smoked a couple of joints, had a great idea, failed to work out how to make it work, and will retire to dream of cordless radios and blah blah blah, all of which ideas of genius you will 'leave to the experts' to actually make work

Yeah. Right!.

You can use alt.binaries.radio-control for pictures and then make a text post telling people here you posted a picture there.

I see. So you have smoked a couple of joints, had a great idea, failed to work out how to make it work, and will retire to dream of cordless radios and blah blah blah, all of which ideas of genius you will 'leave

to the experts' to actually make work

Vance,

Thanks for the suggestion.

I have an idea, in response to The Natural, I can make a mock up of a working system with a servo and trailing edge with a working aileron.

Then I will put a few photos of the working system onto a CD. For anyone interested, they can rent a PO Box, if they don't want their true addresses divulged, I will send them a CD.

I'm not just day dreaming. Just want to let people know it can be done, albeit not with the ideally designed servo.

Send the PO Box address via this usenet.

Wan

On Sun, 19 Mar 2006 00:48:41 GMT, Vance wrote in :

OK, I see what you mean.

I'd rather have the problems of wiring and standard linkages, I think. :o)

Marty

At least he had something mildly thought-provoking to say, unlike some other people.

Steve

Come on now TNP , how about something positive to say. Wan has a good idea. Some people can go from start to finish with there ideas, others need some help along the way......but the end result will be something good that we need.

Mike R

What about the problem of flutter caused by excess weight in the control surface? It's probably best to leave the servo in a non-moving surface for that reason.

Geoff

Hi, Ed and Geoff,

I just measured some of the smaller standard servos, the kind that I use in my 46 inches airplanes. I found the servo arm axis on 3 of them measure an average of 7 - 9mm away from the servo casing. These dimensions are within the parameters for installation of a standard servo onto the middle of the trailing edge of a wing so that the servo arm's axis would be on the hinge line. The casing will protrude into the moving part, but it is still experimental and could be made invisible in the final servo design.

When I see my friend who have the larger servos on his 120 4 stroke Ultimate, I will measure them and see how they may fit on a larger wing.

The specially designed servo will be made tapered to fit the trailing edge of Aileron, vertical fin and stabilizer. For an electro-mechanical minded person, there may not be any problem.

My offer to make a mock up and send a photo CD still stands for anyone interested.

Wan

The specially designed servo will be made tapered to fit , vertical fin and stabilizer.

I meant "the trailing edge of wing" in my last post. A typo.

| The servo should look something this: It would be tapered to the | thinness of the trailing edge and the axis of the servo arm would be at | the hinge point between the two surfaces, one fixed, the other moving. | The servo would be attached to the fixed surface on the trailing edge. | The servo arm would be attached to the moving part.

It's not a new idea ... it's been tried before, and it worked.

... but it's also difficult to set up, doesn't allow you to adjust your CoG by putting the servos closer to it (for rudder and elevator servos anyways) and the `usual' systems work pretty well, so there's not that much benefit.

But it's not a bad idea.

Have you taken apart a servo to see what's inside? The challenge for making the casing taper around the output shaft is that there is normally a large diameter final gear on the output shaft. If you wished to do away with this you would probably need to re-arrange the gears and drive the output shaft with a belt.

It is a challenge. The larger gear for the servo arm is needed for mechanical advantage. The casing will have to be redesigned to house that gear. But if it was made to fit closely, it could protrude a little above and below the trailing edge. It still would be a lot neater than a control horn with a push rod or pull, pull system plus control horns.

As for the integrity of the trailing edges of the wing or stab, the solution will follow. I believe any structural problem can be solved. The same may be said about installation, inspection and servicing of the servos. The rudder servo should be relatively easy as the end of the fuse is thick.

Balance is important for our aircrafts. I know of a member of our club with the elevator servo mounted directly underneath with a very sort push rod off he 2 lb fanjet. But his plane has a very long nose section and the Li Po battery is up front in the nose.

Our planes for this "new generation" servos may need an innovative approach to balance.

All this dreaming of a new type of servo can only become a reality if the designers and manufacturers would embrace the idea. Then when the competitions begin, and only then, we may have servos that will make our hobby easier and better. Meanwhile, we can keep dreaming.

I cannot imagine a full sized airliner having push rods and control horns on the control surfaces. Can you? How about any other problems?

Wan

You can run the gear train almost flat and use an angled pin-in-slot to get the movement...

BUT in the end, look at how its done full size. Actuators in the wings and pushrods..I wonder why..

I thought about something along these lines recently before I ever sa

this thread.

What I was coming up with was just a special servo arm shaped t directly engage with a strip aileron material. No linkage required. N ability to adjust the mechanical advantage, either. Would have to se control surface limits at the Tx

-- rocket_ji

----------------------------------------------------------------------- rocket_jim's Profile: