hi, i am worried about an aspect of a plane i am scratch building. for my rudder control, i have the push rod comming up at an angle to my rudder, here are 2 options i have thought of in controling my rudder. the first one here is where the push rod is bent so that the force on the control horn on the rudder is horozontal, and the 2nd picture here is where i have the rudder inclined at an angle so that the forse of te pushrod is not trying to push against the hinges that i will have holding my rudder on.
will either of these work, or would it work with the pushrod bring straight as in picture 2 and have the rudder as in picture1.

eagle4

(as you can guess, i am a newbie at modeling and am deciding to scratch build for my first plane)

How big is this plane? I think either will work for a 40 to 1.20 sized plane...

The key to having a straight pushrod will be mouting the control horn with a twist so that the pushrod does not bind.

If you decide to bend the push rod so the control horn is square to the rudder then make sure the bend does note prevent full control throw. If the bend is too close to the fuselage it may the pushrod exit...

G'day,

If your rudder pushrod needs bending or is at an awkard angle, you might want to consider a pull-pull setup.
The wires can be routed almost anyway you like and a pull-pull will give you a nice positive and slop free setup.

GalenB: the part of the plane that i drew in my pics will be about 7 inches long


apalsson: thats a good idea, i'll definately consider that, so are ther parts i could get to anchor the wires to my vertical stabilizer so that it can be then directed onto the actual rudder horn?

The way it's shown it picture 1 will NOT work. The bending moment on that rod will prevent the rudder from moving much, and I'd guess that the force of air movement would push it back. Picure 2 might work okay.

If you don't use pull/pull, get a flexible rod in a tube set up, like one of the Sullivan Gold n' Rods, or what ever they're called.
Dennis-

I agree with post #5 but don't angle the hinge line of the rudder, it should be perpendicular to the stabilizer.

Stick Jammer would this configuration work? my thought is that seeing sa the rod is pushing at an angle it will be putting too much strain on the hinges that will be holding onto my rudder, because when you push at an angle there are 2 forces at work, a vertical one and a horizontal one, and i dont want a vertical force as i am concerned that the hinges will give way whilst flying and i will be screwed.

this gives you an isea of what i am saying... the component horizontal force is what i want, but having the component vertical force will ut a turning moments onto my hniges which will be adding a lot of strain, if the hinges still hod i believe there will be a resistance to turning due to the increased friction in the hinges, if any of you have encounted this problem and cna solve it for me it would be much appreciated...

In your most recent illustration, if you simply angle the control horn to match the control rod it would work better.
Dennis-

Ok, let's get back to reality here. But first, as ridiculous as this design is, there is no reason why you couldn't angle the hinge line of your Rudder. You probably won't get a chance to use it anyway.

When it comes to designing ANYTHING, remember this: "Form follows Function". That means you don't do anything unless there is a reason for it.

Why does the back of the fuselage sweep up like the Statue Of Liberty's arm? Is there a reason for this? Or are you doing it because it "Looks Cool"?

How many planes have you seen where the rear of the fuse does that? None.

Do you know why?

Because it doesn't make sense.

The combination of the air hitting the front of it and the drag induced at the back of it would cause this plane to constantly want to loop as it flies.

There is a reason why the rear of a Fuselage is straight. It is to MINIMIZE DRAG.

Your design seem to be trying to defy it, and what you wind up with is a "Form in search of a Function".

Don't try to reinvent the wheel. There is a reason why airplanes look the way they do. If you insist on scratch-building your own design, at least stick to what the people much more knowledgable than you have already discovered.

In other words:

All of the mistakes have already been made, why make them all over again?

Wow Minn, that was harsh,lol. I guess its better to find out now before hours of work.

thanks for your concern, but the plane i am designing is froma plane which was built in 1934, the part of the plane you see in my drawings is of the twin tail booms.
(look here for what it is meant to look like http://www.aircrash.org/burnelli/ch_ub14.htm )

i understand why most planes have the tail straight

you are interested in reducing drag, why not consider building a plane which can produce more lift, that is the idea behind what i am making, i am using a lifting body design which you can read all about from the website mentioned above.

i appreciate all your help

dave

DBCherry would the vertical component force be neglegable? so pushing at an angle wouldnt put too much strain on the hinges?

Where ya gonna put the servo? In the main part of the body? Or in the tail right after the bend?
In the tail right after the bend would make setup easy but in the pics it looks like those are built (profile like). Wouldn't want a servo pokin out the side. Hitec makes an aileron servo (thin and flat). One of those might fit.
I'll bet the guys in the scratch building forum will be interested in following this build.

The force would be neglible.

Having seen the design, I would highly recommend using flexible pushrods though. Sullivan makes them, and you can also find braided cable types that run in plastic sleeves. These allow for long sweeping curves without any concern for binding.

Minn,
That's as harsh as I've ever read from you. Knowing you from seeing so many of your posts, that was out definitely of character (that's usually more my kind of post ).
Dennis-

if this is your first plane as you suggest in your first post, i dont think it will make the ideal learning tool. bet thing to do if you want to learn to fly is first, JOIN A CLUB, then get a TRAINER. you will have much success with this combination.

if the burnelli thing is your first build/first fly you are going to waste a lot of money!

MInn... I guess this is one (tiny) case of ye foot in ye mouth :bananahea ... it was actually made... and it actually flew... and actually formo followed (lifting) function...... not to worry we all have had days like that.....

To put icing in the cake... it actually was a pretty safe plane in the event of a crash.. of course it required sloppy maintenance (mecahnic forgot to put the nuts in place in the aileron hinges..[:-]

http://www.aircrash.org/burnelli/movies/ub14crash.mov

The pictures show a twin. You aren't, by chance, building a twin for your first plane, are you? If so, is it electric or glow powered?

While you CAN build something like that, (and I agree with Dennis about the control linkage, btw), I think you'd be much better off building something more conventional your first time out. Twin booms are twice as many things to go wrong, and twice as hard to get everything aligned correctly.

So, I agree with Minn, I urge you to stick to something "simple" for your first try. After you get that working, and see how stuff works and doesn't work, then you can go crazy. In the long run, you'll be better off, I suspect.

If you read eagle4's other posts, you will see how clueless he and his partner are. Neither of them have ever built a model airplane. In one thread one of them asked if bevel gears (like the pic below) is how we control the ailerons.

If they don't know about simple control setups (By the way, Use Sullivan flex rods to control your rudder, that will solve all of the problems) What kind of structure are they going to build.

Do they know what shear webs are? Do they know how to join a wing without having it fold up?

They have been given good advice to buy a kit, and learn what they are doing, but that's "Too Easy". Apparently, they want to learn the hard way.

Have a ball.

first of all, i dont have a partner, its just me

would i learn all about this from building a trainer, or would i still need to learn all about this from more experienced builders?

as you all know i am new to this, paying me out for this is not a big help,



thankyou everyone else for helping me, i have learnt a lot from you guys

Hey Minn,
How deep does that enema go up your @#*?

A little bedside manner goes a long way![:'(]

I am with Minn and others who think you are clueless and trying something not that easy.

I too saw and replied to your aileron gear setup question mainly suggesting you should keep it simple with building and everything.

And I do remember someone trying to scratch build his first plane from scratch from Australia arround the same time you pooed your aileron question.

Just keep it simple and enjoy.

I am new to this hobby and yes I learned what sheer webs are for with my first kit 4*40 by just twisting the wing before and after installing the webs and how they can provide a good structural support for a open bay wing, like 4*40.

Look at other responses when people learn that you are scratch building a twin for your first plane.

After all decision is yours, if you want to pursue your idea, go ahead. One suggestion though look at Great Planes web site, they have manuals for all their kits in pdf and take a look at all of them, study them, their hints are good. Their warnings and recommendations are good. I learned a lot from those and you can see how many different designs, structures is available.

Also do learn how to fly with a trainer.

Good luck and enjoy,

Can we see a video of this planes maiden flight when the time comes?

I a'm an experienced static model builder just getting into r/c even with all my building experience I would not want to attempt to build a twin fuselage aircraft that I was going to fly yet. As a matter of fact I have 2 twin engine kits that I probably won't build for 2 years and not fly for at least 3 years.

Sorry, it's been a little stressful here lately.

It just makes me a little crazy when someone comes here for advise, and then doesn't take it,

http://www.rcuniverse.com/forum/aile...1162753/tm.htm

but insists on bombarding us with questions that shouldn't have to be asked.


Eagle, there are MANY things you must learn about. You can ask your questions here, and you will get answers. But you seem to be the type of person who, when given an answer you don't like, you ignore it, and try something easier.

The next thing that worries me is all of the questions that you may not know enough to ask.

Do you know what CG is? Do you know that if the CG is not correct your airplane (that you put all of that hard work into) could be destroyed shortly after leaving the ground?

I'm not trying to be a hardass, I'm trying to save you a lot of grief. There are many items like CG that are vitally important to the success of any airplane. If you choose to ignore them, they will not go away, but your plane will.

Ok, I won't say anymore on this topic.

Good luck with whatever you decide to do.