wing incidence?riser 100?
06-08-2003 | 02:06 AM
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From: Brossard, QC, CANADA
wing incidence?riser 100?
HI,BOYS
I WAS FLYING MY SIG RISER TODAY WITH A STRONG HEAD WIND AND NOTICE THAT MY SIG HAD NO PENETRATION.SO AN EXPERIENCE PILOT TOLD ME ABOUT ADDING BALLAST AT MY CG POINT AND ALSO THAT MY WING INCIDENCE MIGHT BE NEGATIVE.SO NATURALLY BEING A GLOW PILOT BEFOR GETTING IN THE WORLD OF WONDERFUL THERMAL SEARCHING(STILL USELESS)I NEVER CHECKED FOR SUCH A THING SINCE I RELIED ON THE GLOW POWER AND TRIM TO FLY.SO I WENT TO THE HOBBY STORE AND BOUGHT MY SELF A WING INCIDENCE METER FROM ROBART.TELL ME IF THIS IS CORRECT,WHAT I DID WAS ZERO THE STABILIZER AND THEN CHECKED THE WING AN IT HAD 1 DEGREE OF POSITIVE.WHAT I DID NOTICE WAS THE WASH OUT NEAR THE TAPER WAS THE THE TRAILING EDGE WAS LOWER THEN THE LEADING EDGE.WOULD THIS SITUATION CREATE GLIDE RATIO LESS THEN DESIRABLE OR IS IT THAT THE RISER WASN'T WELL DESIGNED.HAS ANY BODY HAVE ANY GOOD THERMAL STORYS ABOUT THIS PLANE?
THANK YOU.
DANIEL
I WAS FLYING MY SIG RISER TODAY WITH A STRONG HEAD WIND AND NOTICE THAT MY SIG HAD NO PENETRATION.SO AN EXPERIENCE PILOT TOLD ME ABOUT ADDING BALLAST AT MY CG POINT AND ALSO THAT MY WING INCIDENCE MIGHT BE NEGATIVE.SO NATURALLY BEING A GLOW PILOT BEFOR GETTING IN THE WORLD OF WONDERFUL THERMAL SEARCHING(STILL USELESS)I NEVER CHECKED FOR SUCH A THING SINCE I RELIED ON THE GLOW POWER AND TRIM TO FLY.SO I WENT TO THE HOBBY STORE AND BOUGHT MY SELF A WING INCIDENCE METER FROM ROBART.TELL ME IF THIS IS CORRECT,WHAT I DID WAS ZERO THE STABILIZER AND THEN CHECKED THE WING AN IT HAD 1 DEGREE OF POSITIVE.WHAT I DID NOTICE WAS THE WASH OUT NEAR THE TAPER WAS THE THE TRAILING EDGE WAS LOWER THEN THE LEADING EDGE.WOULD THIS SITUATION CREATE GLIDE RATIO LESS THEN DESIRABLE OR IS IT THAT THE RISER WASN'T WELL DESIGNED.HAS ANY BODY HAVE ANY GOOD THERMAL STORYS ABOUT THIS PLANE?
THANK YOU.
DANIEL
06-08-2003 | 10:48 AM
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From: Thomasville,
GA
wing incidence?riser 100?
The inner panels should be flat on the bottom. You want the tips of the outer panels to be slightly higher at the trailing edge than at the leading edge. It's called "washout". It keeps the tips from stalling first when you're flying at minimum airspeed. You can (and should) twist the outer panels of the Riser to get aout 1-2 degrees of washout by reheating the monokote.
I've never built a Riser, but 1 degree of incidence sounds about right for planes with flat-bottom wings like the Oly II, of which I've built several.
Fly the plane at the weight you prefer for your average conditions and see if any up or down trim is needed to keep it flying level. If it needs up trim, increase the wing incidence slightly with a shim under the leading edge. If it require down trim, put the shim under the trailing edge. It won't take much to make a difference. 1/32" at a time would be a good start.
Get the plane to fly level in average conditions with no offset of the elevator. Adding ballast at the CG, or slightly forward of it, on windy days (to get the penetration you need) probably won't change the trim much.
Hopefully this will help make your venture into soaring an uplifting experience.
One of the glider flyers in my first club was always competitive with his old Oly II, which was years behind the state-of-the-art gliders some of the others were flying. And, he rarely flew except for the contests. You won't be able to make the great zoom launches with the Riser, but you'll have a lot of fun learning how to read the air and work lift.
Roger
I've never built a Riser, but 1 degree of incidence sounds about right for planes with flat-bottom wings like the Oly II, of which I've built several.
Fly the plane at the weight you prefer for your average conditions and see if any up or down trim is needed to keep it flying level. If it needs up trim, increase the wing incidence slightly with a shim under the leading edge. If it require down trim, put the shim under the trailing edge. It won't take much to make a difference. 1/32" at a time would be a good start.
Get the plane to fly level in average conditions with no offset of the elevator. Adding ballast at the CG, or slightly forward of it, on windy days (to get the penetration you need) probably won't change the trim much.
Hopefully this will help make your venture into soaring an uplifting experience.
One of the glider flyers in my first club was always competitive with his old Oly II, which was years behind the state-of-the-art gliders some of the others were flying. And, he rarely flew except for the contests. You won't be able to make the great zoom launches with the Riser, but you'll have a lot of fun learning how to read the air and work lift.
Roger
