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I ground looped another cub

Old 04-28-2009, 02:24 AM
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sportrider_fz6
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Default I ground looped another cub

I took my cub out last sunday, and ended up ground looping it smashing the left wing tip down to the aileron. I've rebuilt the wing and my wife recovered it for me( I haven't got monokote down yet) so I'll be back at the field on sunday and try it again. I don't know why I'm so intemidated by the cub. I can fly it and land it fine, it's just the take off that gets me.
Old 04-28-2009, 02:33 AM
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MetallicaJunkie
 
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Default RE: I ground looped another cub

gradually give throttle, gently correct the torque of the motor with right rudder, and ease her up..... easier said than done
Old 04-28-2009, 04:43 AM
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Default RE: I ground looped another cub

Any high-wing taildragger like the Cub or its distant cousins is going to take some getting used to. But after a while, it becomes easy and the rudder use is via subconscious reflex.

NorfolkSouthern
Old 04-28-2009, 07:11 AM
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Stripes
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Default RE: I ground looped another cub

Too much elevator. You are probably jerking it into the air in an attempt to get away from the ground and into the nice safe air. Ground is hard; you want to be away from it, hence you give it more elevator than it's speed and flying conditions justify.
Old 04-28-2009, 07:23 AM
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Steve Steinbring
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Default RE: I ground looped another cub

As mentioned above ..........on takeoff apply power slowly keeping the aircraft tracking straight. Get the tail up off the ground by adding a slight amount of down elevator as you increase power maintaining a straight as possible takeoff roll with rudder. Increase to full power the airplane will fly off the ground with little or no up elevator when it gains enough airspeed to fly. Most beginning Cub fliers try to force the airplane off the ground to soon ending up stalling the airplane on takeoff.

Hopes that helps!


Steve
Old 04-28-2009, 07:39 AM
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MinnFlyer
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Default RE: I ground looped another cub

With a model Cub there's no need to give down elevator to get the tail up. But as others have said, keep it on the ground for a few extra seconds before trying to lift off.

Also be SURE that your wheels are toed IN slightly. If they are toed OUT, that will cause a ground loop every time!
Old 04-28-2009, 07:55 AM
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Korps
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Default RE: I ground looped another cub

Why is the Cub more difficult too fly/take off than other planes? This is just out of curiosity since it seems a lot of people has "problems" with it. I have never flown one so I don't have the slightest idea.
Old 04-28-2009, 08:18 AM
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Default RE: I ground looped another cub

Korps,

Forward location of main landing gear (I know it's a Tail dragger- move wheels back slightly improve ground looping, but make nose over worse), high aspect ratio wing with a near flat bottom wing, small verticle tail in relation to the wing.

To tame the taildragger, Toe-in on main gear, keep rudder deflection to a minimum, take off DIRECTLY into the wind, cross wind TO's can get exciting in a hurry, don't try to horse it off before flying speed is reached.

MTY

also make sure your both main gear wheels turn freely, even if they have a side load. And get a bigger Cub larger fly and ground handle better. (IMHO)
Old 04-28-2009, 08:22 AM
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Default RE: I ground looped another cub

Minnflyer or some one probably has the scientificly correct answer, but here is my observation from experience with my Cubs compared to my other planes. It seems to me the wing span is as long or close to the same length as the fusalage and I think this may be part of the ground handling problem. Using my best redneck analogy, its kind of like the difference between a short wheel base pick up truck and a long wheel base truck. Short wheel base truck is squirely and easy to lose control when you slide around a curve, but a long wheel base truck will track better and straighten up a little easier.
Old 04-28-2009, 08:44 AM
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MinnFlyer
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Default RE: I ground looped another cub

'Specially when yer drivin' on a tarred road!
Old 04-28-2009, 08:49 AM
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Default RE: I ground looped another cub

Darn' tootin.
Old 04-28-2009, 08:57 AM
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goirish
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Default RE: I ground looped another cub

Hummmm!!! the next cub I build will have a 8' fuselage.
Old 04-28-2009, 08:59 AM
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superflea
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Default RE: I ground looped another cub

with my 60 sized cub (with a 75 on it) I need to hold up elevator for the early part of the takeoff roll, gradually releasing it as it picks up speed. This happens very quickly. That part about releasing elevator is important you can not hold up elev. till it flies because it will stall if you try it. you must let the tail come up. With mine I find that I am at about half throttle when it is at flying speed and only give it full throttle once in the air. but as I said I'm flying with a 75, way more power than needed. That may or may not be helpful, but A bit of advise that you really should consider is do not chase it around on the ground. Try to hold your heading but when it starts heading south, cut the power right away and try again. DON'T CHASE IT.
A cub will fly very slowly dont think you need to be at full power full speed before lifting off. A cub forces you to fly it right, most trainers etc. let you get away with ham fisting it around, but a cub won't. just take a deep breath, slow down and try again. slow, gradual, and gentle with the sticks and don't be afraid to close the throttle and start again.
Old 04-28-2009, 09:00 AM
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hugger-4641
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Default RE: I ground looped another cub

Not a bad idea, might knife edge a little better.
Old 04-28-2009, 09:59 AM
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Steve Steinbring
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Default RE: I ground looped another cub


ORIGINAL: MinnFlyer

With a model Cub there's no need to give down elevator to get the tail up. But as others have said, keep it on the ground for a few extra seconds before trying to lift off.

I agree to a point!

Here's why! A Cub type aircraft in a three point landing or takeoff attitude is at a fairly high angle of attack easily stalled without enough airspeed. When I suggested adding a bit of down elevator it was to get the tail up flying quickly then gain adequate airspeed before lifting off. A great many inexperienced Cub fliers attempt takeoffs from a three point attitude hoping to fly off using power without adequate airspeed resulting in a stall as the airplane breaks ground most often followed by a quick torque roll. A lot depends upon the individual airplane's setup as most Cubs are overpowered so the tail comes up pretty quickly by itself providing power is applied judiciously. More than often nosing over is a common with too quick of power application with all the excess power available the reason for holding up elevator until the airplanes get tracking enough to raise the tail. Learning to fly an airplanes wing or allowing it to fly off the ground using the wings lift vs. blasting off the ground through the use of power of the prop is a great lesson learned. A Cub is not supposed to be a 3-D type performer its design is a high lift fairly slow flier.
Old 04-28-2009, 10:07 AM
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Default RE: I ground looped another cub

Hi!
The problems with tail many tail-draggers are:

1. Wheels too far forward!
2. No toe-in used!
3. No use of negative camber!
4. Have not yet mastered side rudder steering!
5. No wash-out in the wings!

These are the five most important things you have to to consider when you build and fly a tail dragger!
Old 04-28-2009, 10:08 AM
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Default RE: I ground looped another cub

I remember another tread on RCU about how to lift off a Cub. You hear all sorts, its funny. Slowly throttle her up ... throttle her up quickly ... Well, let me add another. One friend had the same problem and he says it was cured after adding more RIGHT thrust. Well, I seen his Cub lift off many times and its straight. Care to try it?

As for the tail to lift up ... when you gain sufficient speed, it will lift on its own. Happily ...
Old 04-28-2009, 10:18 AM
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Rodney
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Default RE: I ground looped another cub

The most important is what Minni flyer and RC ken said: MAKE SURE YOU HAVE TOE IN ON THE GEAR. If it is aligned properly, a slowly advanced throttle and leaving it stay on the ground until adequate flying speed is obtained is fairly easy. Not for the faint of hearted but; if your gear is not properly aligned and you have lots of power, you can jam the throttle to full and, if you are quick on the rudder, usually attain flight before you dig in a wingtip.
Old 04-28-2009, 10:24 AM
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MinnFlyer
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Default RE: I ground looped another cub

Minni flyer? Am I getting smaller or is it just me?



And BTW, I don't "Blast" a Cub off the ground, I've just never seen one that required any down elevator to get the tail up. Quite the contrary, you usually need to balance the tail with a little up elevator to keep it from nosing over - especially in grass and regardless of engine size.

And I have flown just about every popular Cub on the market from small electrics to 1/4 scale.
Old 04-28-2009, 11:00 AM
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Steve Steinbring
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Default RE: I ground looped another cub


ORIGINAL: MinnFlyer

And BTW, I don't "Blast" a Cub off the ground, I've just never seen one that required any down elevator to get the tail up. Quite the contrary, you usually need to balance the tail with a little up elevator to keep it from nosing over - especially in grass and regardless of engine size.

And I have flown just about every popular Cub on the market from small electrics to 1/4 scale.
Mike,

I made no reference to how you personally fly a model Cub I'm sure your experience speaks for itself.

Its been my observance watching folks flying Cubs or similar type a great many fliers do not fly the airplane off the ground they essentially power it off. Takeoff rolls are short, very short often with the tail never rising. Down elevator may or may not be the proper technique it depends upon the airplane. However, it does reinforce the thought of getting tail off the ground flying. Too high an angle of attack at too low airspeed results in a stall a common takeoff problem.

I have an old Cub type trainer which requires some up elevator on the start of takeoff roll, then just like you said the tail just comes up so it all depends .

I too may just have a handle on this. I too have flown a great many Cubs from the full scale to the model versions. Its nice to explore things these discussions bring out many viewpoints and information for pilots to think about.
Old 04-28-2009, 11:15 AM
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MinnFlyer
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Default RE: I ground looped another cub

I agree, and yes, on a Full Scale Cub, some down elevator is needed.

Much worse that the Cub is the Citabria (Decathlon). If you get off too soon with one of those, you can pretty much bet that you will soon torque-roll back to the runway! [X(]
Old 04-28-2009, 02:59 PM
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Default RE: I ground looped another cub

Any plane that tends to loop or yaw at takeoff, can probably benefit by increasing the rear wheel stance, so the plane sits more level on the ground.

Couple that with toeing in the wheels, and it will greatly improve ground handling.
Old 04-28-2009, 04:10 PM
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Default RE: I ground looped another cub

cheat but a gryo on the rudder
Old 04-28-2009, 05:04 PM
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Default RE: I ground looped another cub

I remember my first attempts at a take-off with a Cub which at times I think was demonically possessed by its ground antics. It definitely didn't handle as nicely as a Smog Hog, that's for sure.

The technique I was told to use has served me well over the years. Start off with full up elevator and throttle closed. As you bring up the throttle let off the elevator so when you hit 1/2 throttle you're off the elevator. Let the plane pick up speed and then give it a touch of elevator to lift off. Even works for a Citabria/Decathlon too! The up elevator keeps the tail wheel on the ground for directional control until enough speed is built up for the rudder to be effective which is about the same time as you are off the elevator.

Or you use the technique I used for my Pilot .25 size Cub (that's the demonically possessed one). It was almost impossible to ROG since the gear was so soft and bent all out of wack so I just hand launched it. Every landing usually required re-bending the gear no matter how gently it was landed.

Hogflyer
Old 04-28-2009, 06:59 PM
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Default RE: I ground looped another cub

Cubs are famous for ground looping on take off and landing. The tall (and box style) side-profile of the fuselage causes it. When applying throttle for takeoff, you must counteract the left thrust by adding right rudder (unless the crosswind is off the right side of the plane). A large amount of right rudder is immediately needed when power is applied, then quickly reduce the rudder throw as the plane picks up speed. This actually becomes a timing thing that you must anticipate (as opposed to react to). By the time the tail section rises off the ground, you should have little or no right rudder applied ... neutral. As the plane climbs, you will need right rudder to keep it flying in a straight line. Cubs also require more rudder input during coordinated turns than any other plane. Without enough rudder input, the Cub will skid through a turn instead of the tail following the nose (as in a coordinated turn). This is all true for full scale Cubs, as well as the small R/C Cub planes.

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