Rudder and Aileron

[Guest Cralis]

Hi guys.

 

I fly remote control helis. Mine run off a 7 channel radio. So you have throttle, blade pitch, aileron, rudder, elevator control, gyro mixing.

 

I just bought a plane (GWS Slow Stick..). It is only a 3 channel plane. Rudder, elevator and throttle.

 

My question is, on the R/C Plane, whne you turn using the rudder, the wings automatically dip towards the side you turn. I think this is due to one wing going slower than the other in the turn - and less airflow to the wing gives less lift. So, add rudder, one side slows a bit and it ends up looking like a coordinated turn - no aileron needed.

 

How come in a real aircraft, if you add rudder only, the plane stays in the same flight direction, bust just slips sideways. One wing doesn't dip.

 

Whats the differences? I think momentum might be the answer. Also, power to weight on the R/C plane is very high...

 

 

[Matt]

How come in a real aircraft, if you add rudder only, the plane stays in the same flight direction, bust just slips sideways. One wing doesn't dip.

Hi Craig - if that's the result you're getting then you're not doing it right ;) Full size aircraft will yaw then roll with rudder only input - being the primary (yaw) and secondary (roll) effects of this control. Most likely you're not using sufficient rudder input - how much rudder should you use to see this? - all of it. Don't be afraid to use all the available control range, that's what it's there for.

 

As your experience and confidence progress, take yourself and have an aerobatic session or two, you will be amazed at just how little control input most folks use in their daily commute, aerobatics requires full deflection of all controls - this takes a little while to get used to.

 

Cheers,

 

Matt.

 

 

[Chird65]

Cralis, actually in a 3 axis plane roll (Aileron) will eventually follow Yaw (Rudder). The instructor types will enlarge on this as I am rusty but Yaw is a secondary effect of roll and visa versa In some planes it just takes longer due to design considerations

 

.

 

See I told you. I was beat again

 

 

[Guest Cralis]

Thanks guys. That's answered then. In my TIFs, I noticed when the instructor put in rudder only, and let go, it 'bounced' back to the direction we were heading, and no wing dip. But it was brief.. maybe 1 second of rudder input.

 

So you *could* fly rudder only? Uncomfortable and less control, but it's possible?

 

 

[Matt]

To get a real display of the secondary effect of rudder (roll) you'll need to put in full rudder and hold it there for a good couple of seconds or more while ensuring elevator & aileron are centralised - ask your instructor to demonstrate this on your next flight.

 

One of the purposes for learning the primary and secondary effects of controls is exactly as you have stated - an alternative should a primary control fail. Yep, you can happily steer around (although at a slower rate) using rudder and no aileron - but, as you've stated, it's not very comfortable and provides for severely restricted roll control.

 

Cheers,

 

Matt.

 

 

[Chird65]

Yes most definitely, I was made to fly rudder only for a whole lesson as I was relying on ailerons too much. As you say less comfortable but a valuable lesson. I’m sure that I would not like it in cross wind.

 

Arggg beat again

 

 

[Matt]

Arggg beat again

Don't be too hard on yourself...another good skill to learn - touch typing ;)

 

 

[Guest brentc]

If you haven't done this already, it would be covered in your first or second lesson - the Primary and Secondary effects of the controls as the others have mentioned. Good that you are thinking about it before you've covered it.

 

 

[Chird65]

Matt, Actually it's a skill I have never learnt (even after 25 years in computing).

 

I don't feel too bad as I normally compose an answer to everyones question to tweak my head. (Hardly ever post as I get it wrong too often)

 

$$$$ have stopped me again from flying so its good to try to remember.

 

 

[Guest Ruprect]

Is your RC plane a swept wing configuration (like a 747 as opposed to straight wing-cessna or Jab)?. A swept wing aircraft will roll immediately with any rudder input. I used to work on airline simulators and I spent many a quiet nightshift practicing the old Kai-Tak airport approach (you have to turn a sharp right in the glidepath). A 747 or 767 needs immediate simultaneous aileron input to counter act the roll effect of the rudder input. I used to do it in all sorts of horrendous crosswinds and got very good at putting her straght down the runway centreline with a full-scale rudder input in before and during the flare, i.e a quick flick to straighten her up just before touchdown. I organised a couple of realworld pilot friends a few hours in the sim one evening and they were really surprised at the different effects the rudder has on a swept wing having never flown them before.

 

 

[Guest Cralis]

The Slow Stick is a flat straight wing like the Jab, just with a lot more ... not sure what it's called. The wing tips are at around 15 to 20 degrees up from the middle. Kinda like a very flat V... So looking nose on, the tips are higher than the middle of the wings. I believe this helps with the stability. The plane it's self is a GWS Slow Stick. It's a 3 channel VERY slow flying plane. The wings are made of a tough polostyrine... they are held to the fuselage via rubber bands, and the sulalage consists of a (carbon fiber?!) rod... around 1cm by 1cm. The tail is basically two flat bits of polostyrtine held on by small bolts and glue. And it has a large rudder and elevator.

 

I haven't flown it yet because there's always a slight breeze... and it really doesn't handle wind too well - but as I am a novice in fixed wing R/C, I'm waiting for a dead calm day.

 

Off topic slightly, but the plane it's self cost $18! Where as a bare bones helicopter costs me around $500!! So less tears when I crash it! :) OK, the electrics on it took the price to $120 which includes the $60 for the 2.4Ghz reciever. Really cost effective little (big, actually) guy. The reason for it is so I can improve my 'nose in'. For those who don't fly, it's 'easy' to fly an R/C helicopter when it's pointing away from you, but when it's coming back towards you - coordination goes all stuffed as you need left rudder/aileron to turn right! :raise_eyebrow:

 

So, a $18 plane will be easier to practise with. :)

 

As it's my first official lesson on Saturday in the Tecnam, I don't think I'll get any R/C flying until NEXT week... Need to do some reading on my BAK. Battling with 'how the4 engine works' . :(

 

 

[Tomo]

$18 R/C plane:thumb_up: that's a nice price.... what size electrics does it take (i.e Servo's, receiver, motor/controller)?, and where abouts did you get it from:question:

 

If you need any help with the engine, your welcome to ask, and hopefully my/our mechanical knowledge will be able to answer them for you.......:big_grin:

 

Cheers,

 

 

[Guest Ruprect]

The Slow Stick is a flat straight wing like the Jab, just with a lot more ... not sure what it's called. The wing tips are at around 15 to 20 degrees up from the middle. Kinda like a very flat V.(

Ahh, I know the one you mean, I looked at one of them myself to learn fixed wing RC because I got a little sick of the small co-axial heli I had and the larger cyclic helis are too expensive for me to keep replacing parts. I just wish I could transfer the electronics off the heli over to save some bucks:thumb_up:

 

That V in the wing is called Dihedral, as opposed to Adhedral where the wings point downwards. Easy way to remember is Adhedral sounds like Cathedral where the roof slopes downward

 

 

[slartibartfast]

That V in the wing is called Dihedral, as opposed to Adhedral where the wings point downwards. Easy way to remember is Adhedral sounds like Cathedral where the roof slopes downward

But that's confusing. Dihedral is what they now call the cathedral where princess Di got married.

 

Just to add value - the opposite is anhedral.

 

And to tie in to the NES, wings with local dihedral angles which change along the span are called polyhedral.

 

 

[Guest Ruprect]

Doh - Anhedral,:hittinghead:

 

The easy way to remember is is princess Ann likes going down on people!!

 

(hey, you brought the royals into it)

 

 

[Guest Cralis]

$18 R/C plane:thumb_up: that's a nice price.... what size electrics does it take (i.e Servo's, receiver, motor/controller)?, and where abouts did you get it from:question:If you need any help with the engine, your welcome to ask, and hopefully my/our mechanical knowledge will be able to answer them for you.......:big_grin:

 

Cheers,

It runs a 200W outrunner brushless motor.. which is way too much power for it, but have been told it may be useful when you're in a wind, or heading the wrong way towards the ground. :)

 

I got it from a site called ReadyPlanes.

 

 

[Guest Cralis]

But that's confusing. Dihedral is what they now call the cathedral where princess Di got married.Just to add value - the opposite is anhedral.

 

And to tie in to the NES, wings with local dihedral angles which change along the span are called polyhedral.

So.... a Boeing 747 has a small amount of dihedral... but under load... it's polyhedral?

 

 

[Yenn]

Get a ride in one of the old Kookaburra gliders. From level flight, put in a bootfull of left rudder. Left wing goes down as expected. Put in a handfull of left aileron without rudder. Left wing goes down and the nose yaws to the right, you don't turn. All due to the downgoing aileron having a great amount more drag than the upgoing one.