• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

How to set up a groundloop

I'd like to know how mass creates the issue. The heavier wheel will likely occilate at a lower frequency/higher amplitude, but I maintain the problem lies strictly with the geometry. I've worked on numerous trucks with this issue in the front end (commonly referred to as "death wobble ") and reducing the weight/size of the rotating mass is not how you solve it. Taking out caster is.

i would agree with MTV on this Perry. My 3200 tail wheel will shimmy on almost every landing on pavement with my tail ski attached. Without it, it doesn't.
 
From what I have read, the majority of ground loops occur because of incorrect technique in a cross wind, Bill's lessons to practice also lead me to believe this. While rereading Mr. Imeson's book " taildragger tactics" he states never land when the cross wind component exceeds 20% of the stall speed. When asked the question of what individuals max cross wind is on this forum I get answers that go well above 75% of the stall speed. What is a proper limit you use? With some of the numbers quoted is it even possible to be done safely on a day to day basis?

For me no more than the minimum required for full windsock deflection or about 15 knots. If it is more than that I'll land crossways or at an angle. I did that at a towered airport last month. The wind was blowing from 24 at 18 with gusts in the 20's. The active runway for light planes was 19. I setup for the left side of 19 and set it down at an angle and stopped before getting to the opposite side of the runway. Everyone was happy.

I have found that when I'm really in tune with landings and crosswinds, that I don't even think about what I need to do, it just falls into place and I've questioned if it really is blowing as much as the windsock says. But it is.
 
I'd like to know how mass creates the issue. The heavier wheel will likely occilate at a lower frequency/higher amplitude, but I maintain the problem lies strictly with the geometry. I've worked on numerous trucks with this issue in the front end (commonly referred to as "death wobble ") and reducing the weight/size of the rotating mass is not how you solve it. Taking out caster is.

Mass doesn't create the issue, but it exacerbates it. I'm not a physicist by any means, and I'm not sure I understand all that's going on here. You're correct in that the caster angle is the primary culprit. But, my point is, you can take a tailwheel with proper caster angle, add mass to the assembly, and it will often shimmy. Sometimes it will always shimmy. My experience with this is with big tailwheel tires and with tail skis. Maybe it's not the mass, perhaps it's that the mass is extended further from the axle, but I can tell you from experience that if you add mass to your tailwheel, shimmy will often follow.

MTV
 
Yeah, I have to agree Mike. The more I thought about it the more I realized the two issues are related. The smaller/lighter tire lets you get away with poorer geometry before it wobbles.
 
Adding mass without changing the geometry or anything else will decrease the natural (resonant) frequency of the mass/spring system.
 
There is simply no substitute for one wheel practice on the ground. I tell students that, while you will use this technique in a crosswind, perhaps the more important lesson to be derived from it is that you CAN control the airplane, even at very slow speeds.

The one wheel drill forces them to CONTROL the airplane at very slow speeds, and improves landing approaches immensely, not to mention hopefully preventing ground loops as well.
MTV

After reading this thread today I went out and practiced one wheel landings (everything seems so much easier in the grass!). I'd felt really comfortable with these a few years ago when I was flying almost every day on grass strips. Tonight was on a paved runway and I didn't feel awesome about my one wheeled landings, however I did a few runs down the runway on one wheel and did just find keeping her straight.

My question is - Can't this cause quite a side load on your landing gear? I almost felt bad like I was beating on my poor plane. Touching down on one wheel if you're not going perfectly straight isn't that pretty hard on the gear? Even when going down the runway on one leg I felt like I was producing side load?
Is this the case or am I just not used to the feeling?
 
Richard,

Yes, you're putting a little side load on your gear. That said, if you'd witnessed a few of my landings, you wouldn't worry at all about the robustness of your landing gear.....:oops: The main thing is to minimize the AMOUNT of side load you put on the gear at touchdown. Once you have the weight on that one wheel, the loads aren't ugly at all.

As someone noted earlier, one wheel touchdowns are easier with a little bit of crosswind, but if done well, they're really no big loads at all. And, as I noted above, a major portion of the value of this exercise is for you to convince yourself that you can finesse the airplane. Landing on one wheel in a calm wind does require some finesse.

And, by the way, folks, while this thread is all about wheel plane flying, seaplane pilots can benefit equally from one float landings and takeoffs. In light chop, touch down on one float, pick the plane up, then touch with the other float, repeat. Again, a confidence and finesse builder. You CAN control the beast.

MTV
 
This makes me laugh, "...it is not going forward and aft all over the place on landing" because I picture all those times I brace each elbow to corresponding hip bone and encircle the stick with my hands, thumbs to fingers, ready to stop the over-motion. I never considered the elevator component before. Mattias, the German, was talking about the rudder but could have told me something about the stick too.
 
I'd like to add variables to groundloop situation; Lately I've been landing the flats with muddy and/or wet grass on mud which now has turned to frozen mud. Add a crosswind and the aircraft can be difficult to control at the end of the rollout with slow speed and ineffective rudder. On a hard surface one can use brake to assist however on the mud the tire locks up with minimal braking.

Separate situation is landing muddy or icy locations where brake cant be applied because it furthers the landing distance and further reduces control on ground with one tire getting ahead of the other. I've heard of pilots locking both wheels when landing similar conditions but these situations are of interest to me on how to further my skills.

thoughts?
 
In a short ldg competition on skis and snow I found the best I could do was land as slow as possible, dragging the tailwheel immediately and as heavily as I could, drop flaps to zero. Brakes only increased the ground roll. Maybe mud works the same.
 
Need to show that one to the NO TAILWHEEL CONTROL CABLE GUYS!! See how the tailwheel is backward on landing, it can cause a lot of problems!!!! Might have been better if he did a wheel landing but looks like it was kind of gusty wind. Tailwheel control is always important. Hoping you will do a good wheel landing is a very poor plan!!!

I use a tail ski for several reasons. If I need to slow on skis I do a several hard tail wags. Getting the ski sideways is hard on the fuselage but it will stop the plane.
DENNY
 
So would you have to drag the tailwheel on with power to get it straight before touchdown? If he'd landed on the wheels, the tailwheel would have still been crooked when it came down, wouldn't it?
 
The problem there was that when he touched down he was “neither fish nor fowl”. He was neither in a wheel landing nor a three point attitude. That put the tailwheel in LIGHT contact with the pavement, with little weight to cause it to stick and trail, but the tail not high enough to keep the tailwheel off till slowed.

I see this frequently in folks new to tailwheels also.

I tell these folks to either perform a full stal landing, get the tailwheel down and weight on it, OR touch tail low, then get the tail up and steer with the rudder till slow enough to put the tail down gently.

He or or she did neither......hence neither fish nor fowl. Watch the elevator after the first touch: Elevator was in trail till the plane had already ground looped.

MTV
 
Last edited:
Need to show that one to the NO TAILWHEEL CONTROL CABLE GUYS!! See how the tailwheel is backward on landing,
DENNY

So would you have to drag the tailwheel on with power to get it straight before touchdown? If he'd landed on the wheels, the tailwheel would have still been crooked when it came down, wouldn't it?

If you watch the landing again, you will see that the tailwheel was in tow during the landing, it only spun when he landed it improperly

Like Mike said, with that type of tailwheel, one needs to make a wheel landing and gently lower the tail as the airplane slows down (When on pavement.)
 
Heres one for you. What’s wrong with this picture?

A6B5F029-98E9-41B8-874C-DBA2AAFA9276.jpeg

MTV
 

Attachments

  • A6B5F029-98E9-41B8-874C-DBA2AAFA9276.jpeg
    A6B5F029-98E9-41B8-874C-DBA2AAFA9276.jpeg
    85.4 KB · Views: 475
So. How do you do a controlled ground loop? Isn't/ wasn't that the question?

I had to do one as I couldn't stop in time or go around and had to do one in my head. Brakes weren't working to full potential and a short runway. Hit rudder one way then hard the other to force the tail around. Stoped with no damage but would have been too long and in the crap if I didn't. Isn't this what the topic was about. Controlled ground loop?

Yea should have gone around earlier but didn't. So don't hit me for not doing that. I already know.

Doug
 
I do that at uncontrolled fields to check for arriving traffic before takeoff. Old habit. Do they still teach it?

Gary
 
See how he is leaning to the left to see if the brake is dragging and causing the tire to stop rotation early (old A&P trick).:lol:
DENNY
 
Wonder where the Go-Pro flick is posted? Camera on top of windshield.

Actually like many I had a close one a few years back in my PA18. Mechanic's helper had bled and pre-loaded the diaphragm masters. After the third touch and go on grass strip the left hot brake expander decided it was done contracting. Pulled left and started loop, skidded on grass then hit sticky gravel. Tried full power briefly against up elevator to hold the tail down then right brake. Slow motion tip forward then power off and...well, there's something special about staring at the ground with the tail up/spinner down. Once the forward momentum got my feet heavy and forward on the pedals there was no pulling them back.

Jumped out and pulled the tail down. We towed the plane to the hangar and left a skid trail behind the left wheel.

Oh well, got that maneuver perfected and maybe out of my system for awhile.

Gary
 
Back
Top