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De Rudder.

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Old 22nd Nov 2010, 19:43
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De Rudder.

Yesterday I went for a fly with an instructor to do some short gravel strip practice, and I discovered something I had not previously known; there is this thing down the back of the aircraft some-place called "The rudder".

Now I am living proof that Cessnas and Pipers are designed to be relatively safe in the hands of complete idiots, and therefore the aircraft can be flown without much knowledge of what to do with this design feature. The rudder is sort of like the Appendix, an organ that seems to have no real purpose in our bodies. It helps us aim at the other end during take-off. You stamp on it hard right to avoid going left when power is applied. It can be used with aileron for side slips, and that's it.

Well I was taught a new use for it yesterday; keeping the aircraft on the centerline when landing, especially on late final, and touching down right on the centreline of the strip, in other words favouring the rudder over the ailerons for directional control and keeping the wings relatively level and away from possible ground contact. No one ever taught me that before. Its use also stops me from lurching off the runway.

I also discovered something else I didn't know. I've been slightly surprised at one school to be requested to land a Piper with full back stick and as low a speed as possible, preferably with stall warning as the wheels touched, something I'd previously associated with Cessnas. I found out why yesterday as well. Flying mostly in winter, I'm used to that low wing giving a wonderful cushioning effect to my ham fisted landings - well yesterday I discovered that when the temperature is Thirty degrees or more, and you are on a high crowned strip, it doesn't! I completely misjudged the flare once, then decided to do exactly what XXXX had requested with much better results. Yes I know about dynamic pressure, etc., etc., but on a hot day you can really feel the aircraft going "limp" if you know what I mean.

A satisfying day. What else don't I know?
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Old 22nd Nov 2010, 19:48
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Sounds like GA still has one or two competent instructors on the payroll. Go flying with that instructor again sometime Sunny. That knowledge and discernment on what a student is doing with his or her feet seems rare in flight schools. On turbulent days, you're feet should be getting a good workout on the rudder in cruise too.

There is very little use required of the ailerons on late final and flare; they're close to ineffective anyway and can exacerbate wing drops. When you have it in your head that ailerons are for roll and rudder for yaw, it can be tough to comprehend how much affect rudder has on roll, particularly at low speeds. You need to get in the habit of not just keeping the aircraft straight with rudder at low speeds, but keeping the wings level (or at the desired bank angle) with rudder as well. It works a treat. Spins were taken out of the training syllabus a long time ago. What a shame.

I don't know whether the +30 degree temp. has any merit on the flare. It's not saying much, but I never noticed it. Unfamiliarity and a high crowned strip probably had more to do with it than the temperature.

Full backstick? It should be second nature for nearly every single engine with a nosewheel. When you're told to do it, you concentrate on pulling back firmly to the stops. When you've done it for a while, it's a gentle application of elevator and you don't even realize you're at the stops. Just fly the plane level at low height while the speed reduces. At some point, you run out of back elevator; the aircraft can't maintain height and that's when you touch down. And don't just let go of the elevators when the wheels touch - like so many other pilots. (Pisses me off when I see it.) Fly the thing until the handbrake is set. When you get more acquainted with the aircraft, you'll be comfortable putting the mains down without full back elevator but continuing to hold the nosewheel off until out of elevator. On takeoff, you should also be applying back elevator and gradually easing off as speed builds until you get to the point where the aircraft wants to fly.

If you want to challenge yourself next time with the instructor, at some point on the flare (make sure it's close to the ground; perhaps within a metre), you can start feeding in power while the aircraft is decelerating. You'll get to a point - way below power off stall speed - where the aircraft seems to be just hanging by the prop. Reduce the power, while maintaining the attitude and the aircraft just drops to the ground. Or if you have a nice long runway and no crosswind, using a speed slightly above stall, put one mainwheel on the ground and hold the other off. You'll need to bump up the power a little when the wheel touches. Run on one wheel for a while, lift it off, decrease the power a little to maintain speed and put the other one down. It's fun to juggle the controls and power and you don't need much bank angle to do it.

Last edited by Lodown; 23rd Nov 2010 at 15:48.
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Old 22nd Nov 2010, 20:26
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Ahhh, Sunny, I've just written a two-part article about this very subject. I recently learnt to fly a tail-wheel, and after discovering that those pedals aren't foot rests, could barely walk. Had to take up yoga just to fly the tail-bugger. But, bygolly, it taught me about flying!
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Old 22nd Nov 2010, 21:04
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Sunfish,
I, too, had not discovered the usefulness of the rudder until I was introduced to the C180 & C185. In either of these one learnt very quickly to use the rudder or bend the aircraft. Also, in basic aerobatic training, the rudder is used for things not often taught elsewhere. After I had been introduced to both the above, I noticed with interest how much my feet moved around when back in a nosewheel.

In other words, if you havn't done so already, go fly a tailey.
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Old 22nd Nov 2010, 21:17
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If I remember correctly you posted about flying a 180/185 a month or two ago? Like the above posts I couldn't believe how much better my rudder work became after some tail wheel time. They really aren't just foot rests

My landing judgement, wind awareness on the ground, surface condition awareness... all of these were dramatically better after a bit of conventional gear time. Stupid nose wheels...
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Old 22nd Nov 2010, 22:19
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You really want to see what tailwheels are for .. go fly glider towing on, say, a SuperCub .. the glider keeps you straight on takeoff ... thank Heavens for runways wide enough to put the Cub back down perpendicular to the flarepath.
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Old 22nd Nov 2010, 22:19
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Or go fly a jabiru. Due to the adverse aileron yaw it suffers, use of the rudder is most essential during all phases of flight to keep that ball in the middle.
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Old 22nd Nov 2010, 23:25
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When I first started flying a Metro, I used to pedal it down final with rudder. Turns out this is not required and compounds any departure from the flight path.

In a lighty, rudder is essential. Once the aeroplane has a bit of weight behind it, the trick is to position it, and don't touch anything!!
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Old 22nd Nov 2010, 23:25
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I have always said the three key ingredients to a good landing are rudder, rudder and more rudder...
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Old 22nd Nov 2010, 23:26
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go_soaring! instead
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Old 22nd Nov 2010, 23:34
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Turns out this is not required and compounds any departure from the flight path.
Are you saying its the Garretts that power those things not the rudder? Well whatdaya know...
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Old 22nd Nov 2010, 23:41
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Quote:
Turns out this is not required and compounds any departure from the flight path.
Are you saying its the Garretts that power those things not the rudder? Well whatdaya know...
Whats your point?
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Old 23rd Nov 2010, 00:20
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GG wrote: "Once the aeroplane has a bit of weight behind it..."

Weight indeed; Part of my initiation was in an a/c with a loaded up belly tank and quartering tailwinds. This sort of stuff was not to be tried unbriefed and unaccompanied. Just when you thought the laden a/c with all it's mass was stable after touchdown, she would begin her little turn. It was then you had to do your quickstep dance routine or else a circle would be scribed; for the uninitiated, an unattractive groundloop.

After one becomes aclimatised to all this, short finals adjustments via rudder become the norm.
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Old 23rd Nov 2010, 00:43
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Whats your point?
Geez it was a joke... bloody Australians.

...or maybe my joke wasn't very good...
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Old 23rd Nov 2010, 00:49
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No zep, no. Don't start the Gobbler on jokes

There will now be a barrage of kiwi jokes
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Old 23rd Nov 2010, 01:38
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Full backstick? It should be second nature for nearly every single engine with a nosewheel. When you're told to do it, you concentrate on pulling back firmly to the stops. When you've done it for a while, it's a gentle application of elevator and you don't even realize you're at the stops.
About half the single (nosewheel) types i've flown will tail strike with this technique, especially if not using full flap.

Every aircraft has a landing attitude that should be reached then let it settle, also approach with the correct speed.

Many schools also teach too higher approach speed which then makes judging the landing harder with greater attitude adjustment and elevator load required in the hold off. Not to mention the effects on landing distance etc..

As far as final approach in crosswinds, crab down final, swing it smoothly straight with rudder as you round out, a little aileron to hold center if its misjudged. Any other method in longer aircraft will leave very unhappy passengers, or create a sideslip developing higher rate of descent and again a harder to judge landing. Smooth co-ordinated use of rudder and aileron will achieve the best outcome just remembering the ailerons outboard of the slipstream will be less effective.

Last edited by 43Inches; 23rd Nov 2010 at 01:49.
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Old 23rd Nov 2010, 02:13
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Weren't the first two posters taking the p!ss?
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Old 23rd Nov 2010, 02:24
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I can't believe what I'm reading. You guys aren't really professional pilots, are you ?
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Old 23rd Nov 2010, 03:02
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Originally Posted by 43Inches
About half the single (nosewheel) types i've flown will tail strike with this technique, especially if not using full flap.

All good aircraft will do that. The better ones will have a little wheel there to help prevent the scuff marks on the Duco
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Old 23rd Nov 2010, 05:45
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The rudder is sort of like the Appendix, an organ that seems to have no real purpose in our bodies. It helps us aim at the other end during take-off. You stamp on it hard right to avoid going left when power is applied. It can be used with aileron for side slips, and that's it.
It has nothing to do with countering the yaw moment caused by P-Factor and engine offset.

I also discovered something else I didn't know. I've been slightly surprised at one school to be requested to land a Piper with full back stick and as low a speed as possible, preferably with stall warning as the wheels touched, something I'd previously associated with Cessnas.
This would put you way up the back of the drag curve with no elevator authority, little aileron authority, large rudder control inputs and nowhere to go in the slightest wind gust. Better to establish a Vref based on Manufacturers numbers and proper flare technique.


I found out why yesterday as well. Flying mostly in winter, I'm used to that low wing giving a wonderful cushioning effect to my ham fisted landings - well yesterday I discovered that when the temperature is Thirty degrees or more, and you are on a high crowned strip, it doesn't! I completely misjudged the flare once, then decided to do exactly what XXXX had requested with much better results. Yes I know about dynamic pressure, etc., etc., but on a hot day you can really feel the aircraft going "limp" if you know what I mean.
For a given Vref (IAS), a change in air density should only affect TAS. Given that TAS = IAS divided by the square of the air density ratio.
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