valleyk

I have a fokker DR1 that like to ground loop on takeoff. Wonder if a gyro is going to make this plane someday takeoff in a straight line.

allanflowers

I use a gyro on my 1/6th scale Sopwith Camel and Pup for rudder. It helps but not a complete solution since the rudders are not very effective until the speed is up a bit. Your DR1 probably has an even smaller rudder.

speedracerntrixie

My Feedback: (29)

One thing that will help in this situation is getting the thrust line situated ( correct amount of right thrust ) and getting a throttle curve that will have the power coming on gradually. If your TX has a servo speed option, you can even use that to slow down the power advance and flatten the torque curve some.

otrcman

Make it take off in a straight line ? Well, a gyro will help some, but the DR1 has a lot of strikes against it for the gyro to be a perfect solution. The most you might hope for is that the gyro will slow the action down enough for you to steer it straight as if it were a nosewheel airplane.

A rate gyro is quick, far quicker than any R/C pilot in detecting the very first inkling of a swerve that builds up into a ground loop. So that's to the good.

But, no matter how quickly the gyro perceives an incipient swerve, it still needs some leverage to keep the airplane straight. Will the DR1 rudder be big enough to provide the necessary leverage ? I don't know. All you can do is try it.

At the very beginning of the takeoff run, your tailskid will help, providing it is steerable with the rudder. Here again, the tailskid needs some leverage. If it's just a metal pad on a hard surface, you can bet it won't be too effective. On grass, it will work better.

Another problem with the tailskid (or a tailwheel, for that matter) is that the skid has no effect at all after the tail comes off the ground. For that reason, it's in your best interest that the tail stay on the ground until the plane has gained enough speed for the rudder to have some effectiveness. The down side to keeping the tail on the ground is that the plane may take off prematurely if you hold up elevator for too long.

If you incorporate a pitch gyro in addition to the yaw gyro, you may find that the tail doesn't pop off the ground as soon as you add throttle. That can be a big help. In an ideal world, the tail should stay on the ground until you have at least 25% or so of takeoff speed.

The other reason for slowing the rate at which the tail raises is called gyroscopic precession. You can look up that term on your computer, but the bottom line is that the spinning propellor will cause the nose to swing left as the tail raises. The faster the prop is spinning, the weight of the prop, and the rate at which the tail raises up, all contribute to the left swerving tendency. As soon as the tail reaches level and stops rising, the precession force also stops. There are still some subtle effects that cause the airplane to swerve, but they're small potatoes compared to precession.

There are many other things that can help to alleviate ground looping, but you asked about the gyro, so that's what I have focused on.

One last thing about gyros: The type you want is properly called a "rate gyro". That means the gyro will react to pitch rate or yaw rate. You don't want a heading hold gyro. Heading hold sounds seductively attractive, but will give you no end of troubles in actual usage. Heading hold gyros work great on helicopters, but not so well on fixed wing airplanes.

Dick

jtisch

What type of DRI do you have? Is the problem only on take off or also landing roll out?

mgnostic

Not much experience with gyros here but I have had a Triplane and a few other WWI types. The first rule of Triplane Club is that we forget about trying to take off from a paved runway. The second rule of triplane club is that we always follow the first rule of Triplane Club. The third rule of Triplane Club is that you always take off and land into the wind. I'm only being a little bit silly here. Even with a tail wheel a Triplane has more wiggle in its butt than a cheap stripper. My local club has a paved runway so I usually taxi out to the grass on the far side of the runway. If there is much of a cross wind I go to the end of the runway and take off from the grass there. Other people have already touched on good throttle management. Most of the WWI airplanes I have flown would happily take off at 12/ to 3/4 throttle. Your mileage may vary here depending on weight and power of your specific triplane but the main takeaway should be don't just cram on the throttle and expect it to fly. My best results seem to come from the practice of get the airplane rolling and then feed in power until it is taking off. Then you can give it the rest of the throttle for the climb out. To some degree it is just a matter of practice. It can be frustrating at first but the Triplane and the other WWI birds are a real hoot to fly. They can be a handful on takeoff and landing but once in the air, most of them, if properly setup, are friendly fliers without a lot of the vices of their full scale counterparts.

OldScaleGuy

My Feedback: (2)

Years ago i had a Byron Staggerwing that was a hand full on the ground, like a pig on ice, (especially on a paved runway).
I installed a gyro on the rudder/tail wheel and it settled it down tremendously, made ground handling a joy.

Boomerang1

An old free flight trick is to lock the wheels onto a rotating axle so they both rotate together.

Of course this would mean taxiing is no longer practical - your choice.