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ground loop? explain?

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ground loop? explain?

Old 04-01-2006, 12:44 PM
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treedog
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Default ground loop? explain?

can some pls. explain a ground loop and what causes it and how to avoid it. i've seen it... ahem, but didn't know the exact details of what caused it ty
Old 04-01-2006, 12:51 PM
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Rodney
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Default RE: ground loop? explain?

There can be many causes; to much rudder control, main gear to far aft on a tail dragger, toe out instead of toe in on a tail dragger, to much nose gear throw on a trike gear. I'm sure there are dozens more but these are all common ones.
Old 04-01-2006, 05:56 PM
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Default RE: ground loop? explain?

the most common cause is a quick engine burst and no rudder input to counter act it. The engine just torques it around. Solve the problem by learning when and how much rudder to use.
Old 04-01-2006, 06:09 PM
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khodges
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Default RE: ground loop? explain?

Ground loop occurs when the tail comes around too rapidly and the planes c/g being high enough, usually will cause the plane to tip onto nose wheel and one main (tricycle gear), or tail wheel and one main (conventional gear), one wingtip drops and usually contacts the ground. Models may not even have any damage, but full-size planes can incur fairly severe damage to the landing gear struts and wings.

Causes can be too little toe-in on the gear, poor rudder control, crosswinds on takeoff and landing higher than the plane's max crosswind component (which goes down as pilot error). Some planes are notorious for being rather tricky to handle; the L-19 BirdDog suffered a high number of operational mishaps due to ground looping, usually attributed to pilot error.
Old 04-01-2006, 07:51 PM
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Default RE: ground loop? explain?

Put a Gyro on the Rudder Servo; works great, I have a Decathlon which are famous for ground loops, with a gyro onboard never a problem again, say goodbye to ground loops.
Old 04-01-2006, 07:59 PM
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HighPlains
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Default RE: ground loop? explain?

main gear to far aft on a tail dragger
I'm sorry, but I have to disagree with your assessment. The farther ahead of the center of gravity the landing gear is, the more likely an airplane is to ground loop. Having the gear too far forward also makes it more difficult to land without bouncing. The only thing having the gear forward does is help prevent the plane from nosing over, so there is a trade-off.
Old 04-01-2006, 08:44 PM
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Default RE: ground loop? explain?

ty all for ur kind help. so if i understand all of u, eratic rudder control on take off and some brands/types of planes are more ceceptible to ground looping. is that about it?
Old 04-01-2006, 11:21 PM
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Default RE: ground loop? explain?

Correct; some planes are worse than others.
Old 04-02-2006, 12:15 AM
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khodges
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Default RE: ground loop? explain?

some pilots, too.
Old 04-02-2006, 07:52 AM
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Default RE: ground loop? explain?

Old WW11 fighters were more prone to this. A taildrgger aircraft, especially because of the nose high attitude, resulted in more thrust been produced on the downgoing blade than the upgoing blade. Therefore if they were to gun it on takeoff (low speed, reduced airflow over the tail / rudder, high thrust) - they wouldnt be able to control the yaw with the rudder and thus groundloop.

Some full size aircraft such as Cubs, Tigermoths etc didnt have brakes, therefore if they were going to run into the fence on landing they would intentionally grounloop to stop.

Model engines turn clockwise when looking from the rear, so a sudden increase in power at low speed will more than likely cause a yaw to the left. Compensate with right rudder at the start of the takeoff roll, and reduce as airspeed incresaes. See if that works.
Old 04-02-2006, 08:41 AM
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muzzlemaggot
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Default RE: ground loop? explain?

Any particular type of plane of yours this is happening to?
Old 04-03-2006, 09:44 PM
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Default RE: ground loop? explain?

Ground loop is also caused by gyroscopic precession, I thought. Precession is greatest as the tail lifts to horizontal in take off.

You can feel this effect by lifting the tail of your aircraft while the motor is running. As you lift the tail, it pushes to the side.

The problem can happen when the main gear is too long. I remember reading about ground looping problems in either the ME 109 or the Spitfire. The solution: a higher tail wheel bracket: less movement of the tail to horizontal therefore less precession.

WWI planes had huge precession problems because of the rotary motors. (the mass of the gyroscope was huge). Plus, they typically had a very nose high attitude, which meant the tail had to move a lot to come to horizontal.



Old 04-04-2006, 07:27 PM
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khodges
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Default RE: ground loop? explain?


ORIGINAL: snitch

Ground loop is also caused by gyroscopic precession, I thought. Precession is greatest as the tail lifts to horizontal in take off.
That might explain part of the cause of ground looping on take-off, but a lot of them occur on landing, and typically, power is pulled way back, so gyroscopic precession should be minimal then. Loss of sufficient airspeed for the rudder to be effective, or riding the brakes unevenly (full scale) can induce a ground loop on landing, by starting a yaw that gets too severe for the tailwheel or rudder to straighten out.

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