Tweety Bird - Flying Wing

Tweety flying indoors, plane flies well indoors or outside in light breeze. It might be good to experiment with a rudder tab for indoors flying.

Tweety Bird Notes

Have to admit, I built the first plane without any plans, just cut and glue and hope for the best. A friend had built a couple of similar planes, so I had some idea what I wanted it to look like.

One thing I overlooked from his design was the length of the nose moment, the CG on a flying wing has to be far forward. In my first trimming session I ended up with a wad of clay on the nose, almost as heavy as the rest of the plane. The CG should be no farther back than one inch from the leading edge from what I have seen.

Proper CG balance wasn't the only problem I was having with the trim. In fact it looked rather hopeless to start. The plane would be flying along, and go into a spiral dive. My friend let me get just disgusted enough, and then offered some help. He lowered the elevon on the inside panel of the outside wing a bit, suddenly the plane was actually flying.

Went home and took the razor saw to the front of the motorstick so I could splice on a longer section of motorstick. Now I could get rid of that huge lump of clay.

My first flights outdoors were really a surprise, the plane kept circling upward for most of the motor run. The altitude was about the highest I have seen with a small plane with a plastic prop. For indoor flying in sites with exposed beams the plane will often flip over when it hits a beam and continue flying with little loss in altitude. Kind of an aerial somersault.

When I realized what a good flier Tweety was, I measured the plane and made a rough sketch. A friend whipped out a plan in Autocad, and the second plane was built using slightly bigger wood. This plane flew great with very little adjustments from the start.

Flying wings are more of a challenge to trim, CG placement appears very critical. Evidence of this is the violent change in flight path as the rubber winds down. A smooth flying plane, will start a series of violent stalls as the rubber starts hanging loose from the motorstick and the CG moves rearward. This is more of a problem with larger rubber, so it is important to keep your plane as light as possible to use smaller rubber.

Construction Notes

Note: Plans are not to scale

Having built Tweeties with two different sizes of balsa wood, 1/16 inch square and 1/16" x 3/32", I would recommend using the smaller wood if possible, the performance will be better. The plane is pretty rugged, but will break with a really hard hit to a solid object. Both of my planes were covered with jap tissue, but maybe a lighter covering could be used.

Flying

The elevons are attached to the rear of the wing with copper wire and adjusted with from 3/32" to 1/8" up at the trailing edge of the elevon. If the plane turns too much in one direction, lift up the outside elevon on the opposite wing. I still have a lot to learn on this, and welcome any suggestions. As far as rubber, 3/32" might be a good starting point around 15" loop, again much experimentation can be done. On the second plane, I tried a 6" gray Peck prop outdoors with 1/8" rubber outdoors and the plane was a bear to trim outdoors. So far I have not been able to get much of a glide outdoors, the rubber shifts as it completely unwinds, the CG changes, and the plane goes nuts.