Malo sam proucavao winglete
teorija kaze da bi A tip bio najbolji,
praksa ( misljenje onih koji su testirali) je pokazala da B oblik u praksi bolji jer kod vecih brzina A nije dovoljno cvrst te je tezi za izvesti kako treba.
The greater the stretch of its winglet,'D better.
Would I say because in aeromodelling - in practice - it is difficult to abuse the stretch, and it ends the winglet as you suggested (triangle, going down) is firmer.
Doing more with stretching, just giving flutter in dives.
drawings I made to see if that was what you were talking about:
A = greater elongation, theoretically better, and worse in practice.
B = low elongation, theoretically inferior but better in practice.
Ovaj tip je testirao thermal i dobio zanimljive rezultate ali nema slika
http://www.charlesriverrc.org/articles/zagithl/zagithl.htm#Fun With Winglets (Tom Nagel)
Fun With Winglets (Tom Nagel)
For the last several months I have been experimenting with my Zagi-THL, trying different kinds of winglets. Here is what my notes show, for what it's worth.
1. I started with fairly large winglets, made from styrofoam sheet stiffened with tape strips, more vertical and more rectangular than the triangular shape Jerry ships with his kits. Size: 4 3/4" long, 6 1/2" tall, chord tapering to 2 1/2" at the top. Twenty-four square inches each. The winglets ended at the wing-elevon hinge line. The plane sloped well, but thermal turns were hard to do, and I couldn't achieve thermal flight from a handlaunch. Sometimes, while attempting to thermal if I turned too tight or slowed down too much, the THL would go into a death spiral. Bummer.
2. In an effort to lighten the ship and achieve hand-launchability, I decreased the size of the winglets and the plane still sloped and tracked fine; I got one decent handlaunch thermal flight. And the death spiral problem seemed to go away. Tight thermal turns were still difficult. Size: 4" long by 4 1/2" high, tapered to 3" at the top. Fifteen square inches each.
3. I decided to try moveable vertical fins, attached to the elevons, the theory being that since the hinge line of the elevons is not perpendicular to the Zagi's center line (ie, swept wing) a vertical fin attached to an elevon would achieve some "toe-in" as the elevon came up. And the fin on the "down" elevon would be mostly out of the airflow. I made two light balsa "elefins" in a sort of T shape, and taped one to each outboard end of the elevons. I left the small winglets in place. The elefins were 2 1/4" tall and 3" long, sheet 1/16th balsa.
I couldn't tell much difference in the model's flight. All I learned was that the elefins held up pretty well, and were easy to tape on.
4. So, I ripped off the winglets, and flew with elefins only. I was able to handlaunch and highstart launch with no problems. I was surprised to see that the Zagi still tracked and turned with only the tiny (size) elefins as verticals, maybe 7 square inches each. And I decided that I was not seeing any great increase in turning ability. Maybe the elefins were too small.
5. Just for fun, I tried flying the THL with NO WINGLETS AT ALL. It launched on a high-start just fine, but was difficult to fly. I couldn't hand-launch at all without fins. It would be interesting to see just how little vertical surface is enough to fly with. But I wasn't after "enough"-I was after "optimal."
6. I made bigger elefins. They were about the size of a playing card, 3" long by 4" vertically, about 12 square inches each. The plane flew and turned well, but started to "Zagi-bop"--it would flutter on launch, with the elevons vibrating. Apparently the larger elefins added too much mass out there on the elevons.
7. I started using a new shape of the smaller fixed winglets: a 1" fence extends along the chord of the wingtip, back about 2/3 of the chord, then the winglet becomes a vertical rectangle which extends back over the chord of the elevon. (About 19 square inches each.) The major change here is that the winglets now extend back across the elevon chord. I got good turns and good control, and the Zagi-bopping stopped. I got a 9 minute thermal flight.
My current theory is that both the wing-tip fence and the elevon-capping vertical fin are necessary for decent performance. The vertical needs to be back as far as possible, and block the end of the elevon as well as the end of the wing. A sufficiently picky builder might be able to combine the elefin idea with a low wing-tip fence, perhaps using a quarter-circle forward extension of the elefin to mate with the wing tip fence, and build the whole thing without too much of a drag penalty. I am not talented enough to accomplish that.
8. Currently I am using "ruddered" winglets on my Zagi- THL. I made a square-butted vertical cut in the winglets described in (7) above. The cut is right at the end wing's trailing edge, at the junction with the LE of the elevon. I used a strip of tape to hinge the ruddered part to the fixed part. It is free to flop outboard only, prevented from flopping inboard by the elevon and the square-butted hinge line. Each of the two ruddered sections has a triangle shaped piece of very light music wire taped to the trailing bottom inboard corner; when the elevon comes up, the wire triangle pushes the rudder out.
The light music wire is from the high notes on a hammered dulcimer. You only need a few inches. Check your guitar shop. Make this shape __/|__ then bend each of the legs 90 degrees in or out and tape the "triangle" into place after you have your Zagi trimmed out. The / part of the wire triangle needs to touch the outboard edge of the elevon near the trailing edge when the elevon is is normal glide position. There is no significant weight or drag penalty and the ruddered winglets seem to help the thermal turns a lot. The THL still flys slope just fine, even inverted.
Other experiments:
I had a whole stack of leftover stryofoam winglets made up for Zagi experiments. I had never been happy with my handlaunch Gnome. I think I got the shape of the wing tips wrong when I built it. I cut off the rounded wingtips, squared up the ends of the wings, and taped on a more or less vertical set of winglets. It became a much nicer flyer, with a lower stall speed and groovier turns.
My buddy Travis has a TG-3 with square wing tips. He was having trouble setting up thermal turns and getting short thermal flights. I taped on a set of leftover Zagi winglets. Since the wing tips on the polyhedral TG-3 were cut perpendicular to the bottom of the outboard panel, these winglets had a an odd-looking inward lean. Stealth TG-3. Nevertheless, the stall speed seemed to drop, and the plane began to fly more smoothly. Travis began to thermal up, where before he had just been gliding down.
All of these winglets are just taped on with double- sided scotch tape between the wing and winglet. Sometimes I add a piece of single sided tape on the wing bottom, for security. I have yet to see one of these blown off or flutter even on a vigorous winch launch, except in cases where the tape or winglet had been messed up by a previous crash landing. Replacement is easy. Sheet strofoam is easy to come by--grocery store meat trays and restaurant carry out boxes are good sources. Give it a try!
Poanta moji wingleti su ogromni,
bez wingleta ne valja,
Plavi dizajnira najbolje.
Topic: RCWings Zagi XL (Read 95170 times)
previous topic - next topic
