vikas1974

Hi all

I wish to know that if i am using ailerons, do i require rudder ? I don want to use rudder when i am using aileron control !
Please guide me !


vikas
<<Edit - Tired of "Impoliter" (ruder) corrected spelling.>>

Rodney

It depends on the plane design. If there is lots of dihedral, no or little rudder is required to make smooth turns. If there is little or no dihedral, you will need rudder to make a decent turn. If you practice using rudder in conjuction with the ailerons, you will find your flying greatly improves. There are some times when you will even want to cross control such as when doing side slips.

greenboot

My Feedback: (1)

Most trainer planes can be flown without using the rudder. You will find that more advanced pilots do use it however to improve their flying. Aerobatic pilots MUST use the rudder to perform manuevers well.

Tom

BMatthews

This just isn't true. Sorry Rodney.

The "smoothness" of the turns when using ailerons only has much more to do with the spiral stability of the design. This is based mostly on the size of the vertical tail area and the moment arm of the tail. Large fuselage areas both in fron or behind the wing also have some effect. I've flown many models with aileron and elevator only where there was no dihedral at all and they flew just fine in the turns.

BUT.....

Rudder control is most often required when taking off in a cross wind. For handlaunched models this can be avoided but for larger models I don't see how you can do without it where there is going to be a longer takeoff roll.

Vikas, what sort of model are you trying to do this on?

Edwin

My Feedback: (2)

I teach my students to use the rudder early on. Mainly during landing and cross wind takeoffs. It can turn hairy situations into NON-events. For instance, when turning on final you are typically going slow. Most newbies use the ailerons to turn and line up to the runway. You have two events working against you at that point, slow and your wings banked (usually pretty steep). The bank causes some loss to lift and your slow speed compounds the problem and newbies generally correct with elevator which turns it into a stall. Seen it happen over and over, even after they solo. Rudder is hard to get used to for newbies but the sooner the better. I teach them to use the rudder to line up to the runway and use the ailerons to hold the plane level to keep what lift they have along with about 1/4 throttle up to the runway threshold. Then chop to idle and land.
Edwin

Mike_Mc

The question used the word "require(d)" and not the word "smooth". The answer is no. It doesn't matter much what plane it is, if it has ailerons, rudder is not required. It would make life much easier in some cases to have one, and it's good to learn to use it correctly, but it's not required.

No disrespect intended, but just my pet peeve about telling people what they want to know and not what we want them to know.

Mike

Rodney

Sorry to dissagree with you Mathews, but dihedral introduces yaw coupling, the same thing a rudder does, so more dihedral, the more yaw coupling and less need for rudder.

Tall Paul

Vikas, the need to use rudder, if the plane is designed for ailerons, is limited to takeoff and landing for the most part.
Ground handling, etc.
A plane with a LOT of dihedral will fly perfectly well rudder-only. Such as a kit-stock SIG Kadet Senior. Or any similar "odl-timer" free flight converted to radio control. It's the dihedral that makes turning with only the rudder possible.
It is common to lower the amount of dihedral when a plane intended for rudder control has ailerons added, if only because the amount of stability provided by the dihedral is now provided by the -pilot-!

TLH101

My Feedback: (90)

Rudder is not "required" to fly with ailerons. But if you want to advance your flying skills you need to learn to use rudder, just as you would ailerons and elevator. More complicated models will require it to fly correctly, and some maneuvers will also require rudder. I was taught to fly without rudder, except on take-off. It was the worst thing I could have done. Now I have to make a conscious effort use rudder, it's just not instinct. I keep working on it and I am getting better.

BMatthews

Rodney, contrary to your idea that dihedral with ailerons helps I've seen references to it actually being a problem in sailplanes where folks convert poly ships to aileron and don't bother to reduce the dihedral in the process. Something about stronger than normal adverse yawing or somesuch. I'm basing my, admitedly arbitrary, reporting here on those stories. Are you sure that you're not confusing this with the rudder yaw induced roll that is required for rudder and elevator flying?

Also as stated I have on many an occasion flown both power sport types and a 2 meter sailplane with little or no dihedral and had wonderful success.

The glider was a notable landmark in this as I used this as a test model for spiral stability vs fin size experiment. I found that too much made the model very unstable and too little introduced lots of tail hanging low stuff and adverse yaw. Dihedral on that model was in the order of 1 1/2 inches over a 2 meter span. At the best size it was a very nice model to fly either level or in turns. No rudder but with differential in the ailerons produced a very easy and groovy turn with no visible side slip in the turns.

David Cutler

Any aircraft with a high aspect ratio, like a glider, will yaw out of the turn more as the down aileron on the outside wing creates more drag (basically higher lift = higher drag) and the extra moment that comes from the larger distance from the aileron to the CG has a greater effect.

Also, it could be argued that the lower wing loading that tends to go with models with dihedral will make them less prone to yaw in a turn, and therefore less rudder is needed to make a coordinated turn.

Having said all this (!) it's always a good idea to get used to using rudder, as it's almost always the last control surface to stall in adverse conditions and can therefore be more useful when, for instance, a tip stall happens on landing. When one side of the wing stalls before the other, ailerons could get you in more trouble, whereas rudder could save the day.

-David C.

vikas1974

Thanks all of you for your suggestions.Please keep pouring more information on this subject


vikas

BMatthews

Vikas, you still have not said what sort of model you wish to do this with or why. Some extra information on what sort of flying you want to do in this manner would help. By now you must see that in most cases a rudder is benificial but not a certain requirement. The type of flying you do makes all in difference in how important a rudder would be. For example a larger scale model certainly requires one while a hand launched 1/2A or electric speed 400 racer definetely does not. So where do you fit in?

vikas1974

I wish to make a trainer type model,not very fast (clark y airfoil) and .OS .25 FX engine

Rodney

BMatherws, I must aplologize to you. What I said was not correct, I must have taken my stupid pills that day. I was replying to the question that wasn't asked (Is ailerons required) not (is a rudder required). I don't know what I was thinking other than if you are using rudder/elevator more dihederal is required when you do not have ailerons. sorry, sorry, sorry.

BMatthews

No problem at all Rodney. We all have a brain burp now and then. You had me going there for a moment. It wouldn't have been the first time I've had one of my long held beliefs shot down in flames....


Vikas, for a trainer model that need to be able to taxi around and take off in cross winds from it's landing gear then you WILL need rudder. Ailerons don't do anything until the model is at least light on it's wheels and cannot deal with shifts of direction during takeoff. You need a rudder function for these things.

I'm assuming here that your radio is less than 4 channels and you're trying to shift to ailerons without buying a new radio. This is fine but you would be best to make a hand launched model in that case. Also I gather if you want a trainer then you NEED to be trained to fly. Making an aileron- elevator model as your first model is not a good idea. You would be much better to make it a rudder-elevator-throttle model and forget the ailerons until you either can fly well enough to make a semi racer'ish flat winged handlaunched sport model or buy a new 4 channel radio. And if you do go for the rudder elevator option then you WILL need dihedral. If you want to use an ARF that was originally intended for 4 channels then increase the dihedral so it works better with the rudder. For rudder control a 4 foot wingspan high wing cabin type trainer should have at 3 to 3 1/2 inches under each tip for proper response. A little more up to about 4 inches wouldn't hurt either.

CoosBayLumber

My Feedback: (1)

Just to throw some counter-comment into the subject, but didn't a few the Northrop flying wings operate without rudder and big time dihedral?

I thought they had some sort of wing tip spoilers to control direction.

Wm.

heli001

My Feedback: (5)

Coos,

I think they had these type spoilers on the wingtips:

___/
\
Sorry for the BAD interpretation......If I remember correctly, they had a terrible time with Yaw control...it was almost impossible to land the thing in a crosswind. Also I believe this is one of the reasons that the military rejected the design.....they couldn't accurately control it's destination unless the flightpath was going the same way the wind was blowing at altitude. Think they also crashed one due to this problem.......

Flypaper 2

Yes. the ailerons opened and closed like a clamshell to cause more drag on one side than the other. The stealth bomber uses the same method but done electronically. Just ahead of it's time.

crashed2

My Feedback: (4)

For what its worth, here is my 2 cents.

You can fly a plane with just Ailerons and elevator, But I would suggest (and this is what I would do), if you are going to build a plane, why not build it with a rudder! In the air you don't even have to touch the rudder control, but for takeoff and landings, and ground control, you will thank yourself for building a rudder on the plane, and if you do decide that you want to start flying with a rudder, for the so called corrodinated turns, its already there. You could also put a solid mounted control rod on the rudder with no servo, which would be the same as no rudder at all, but you would still have the ability to make yaw trim.

Just food for thought!

nedyob

My Feedback: (67)

Hello Vikas 1974,
This is what I did when I was learning with my trainer. Use a Y-harness and hook one lead into the Ail. slot in your RX and hook the Rudder servo lead & the Aileron servo lead into the Y part of the harness.
Then you just use the Aileron stick when making your turns and the rudder stick is not used.
Only bad thing is this set up should only be used with the trainer flat bottom wing.
This set up doesnt work with the semetrical bottom wing like your more aerobatic planes.
I mostly use my rudder in windy condition. When flying a half cuban 8 (with wind blowing in) I use left rudder at the left end of the field and right rudder at the right end. This would be done between the 10 o'clock and 2 o'clock possition of the top part of the loop (with the plane in the inverted posittion)
Dont let the use of rudder intimidate you, you just got to think out your control inputs and after awhile it become automaitic.
Just my opinion.
NEDYOB

cappio777

My Feedback: (2)

Edwin, on the contrary, whenever you are in a condition where its low and slow the use of rudder is dangerous. The yaw effect will cause more lift on one wing than the other which would lead to whats know as the "death spiral". Thats the reason why many real aircraft accidents happen right on final approach. On those situations turn with ailerons and only use rudder to line up wtih the runway, then keep the wing facing the crosswind lower until touch down. As a CFI thats something we drill in students heads to avoid fatal [&:]accidents.

Doug Cronkhite

My Feedback: (34)

As a CFI you TEACH people to use the ailerons when slow? How completely backwards. In most light aircraft, using the ailerons when very slow will actually stall the wing with the downward travelling aileron as that downward travel increases the angle of attack on the wintip beyond critical AoA. In this situation, the rudder is your friend. I can fly a C-152 around all day long at 55kias using only the rudder, but as soon as you use the aileron in any large movements, you'll stall the 'outboard' wing and enter a spin (not 'death spiral') if you don't stop it.

Vikas.. to answer your question.. The rudder is a PRIMARY flight control and should not be ignored. If you progress to any kind of aerobatics flying you'll find you use the rudder more than anything else (at least in competition), so why not learn to use it properly from the beginning?

cappio777

My Feedback: (2)

Asymmetric lift can be induced by yawing the aircraft. In conditions when low and slow the wing towards the inside of the turn is not traveling at the same speed to the relative wind. If those are conditions near stall speeds that wing will stall before the other one and induce a spin. You dont enter or recover a spin with aileron input....on the contrary, the only control used to initiate and break the spin is rudder. The NTSB has written numerous articles regarding this issue. If you have been trained in spin recoveries this is not a concept to be disputed.

BMatthews

Cappio, that use of ailerons at low speeds is very counter to my model flying experience as well. I still do it but I'm very careful to not use excessive ailerons at low speeds. In particular I had a 2 meter sailplane that we rudder and elevator only and even with lots of differential I had to be very careful to use very light control applications if I was at the lower end of the speed spectrum. OTOH I've never had ANY of my rudder elevator models ever drop a wing as the result of using large amounts of rudder at low speeds. But of course all my rudder-elevator models are either polyhedral types or have larger amounts of V dihedral to work with the yaw couple.

Perhaps this is different for full sized stuff but I suspect full sized sailplane pilots are carefull to avoid larger aileron throws at lower speeds much like we do. And in fact thinking about this makes me realize that I generall do not use large amounts of control at any time that I'm hanging on the edge of a stall. I guess I figured out that this was not a good thing a long time ago and just do it instinctively now unless I've got plenty of height and I'm just goofing around.