How to test the WS plane?

[Merabethzhuk]

How do you start to test an WS plane? What do you need to measure? Also, when I tested my plane, the rubber knot got in the way and wouldn't turn my propeller. So what is the best way to test? Thanks.

[JasperKota]

If you check out this detailed guide https://www.soinc.org/sites/default/fil ... iad5.0.pdf, it should have a section on testing the plane and knotting the rubber.

[Merabethzhuk]

Thanks, sorry, I have a lot of questions. Is thinner rubber better than thicker rubber? My plane is the laser cut Vanguard P-18, no modifications.

[bjt4888]

Merabeth,

Here is a detailed set of testing notes that i wrote for a demonstration test of the 2015 rules Wright Stuff airplane. I've also attached a picture of my 2015 demo airplane

Wright Stuff C 2015

:

Here are my flight test results. My site is 23' 6" from the floor to the lowest obstruction (multiple 3' round air vents projecting from the ductwork) and is the size of one basketball court with about 20' extra along one side for pull-out bleachers. Air is fairly calm as the HVAC systems are shut off this time of year on the weekends. Once I had the airplane decalage trimmed-out per procedures on Bill Gowen's plan, I tested what i am calling .098", .095" and .090" tan super sport rubber. I made no alteration to my initial center of gravity (1.5" behind the wing training edge) as I wanted to fly with the designed 15% static stability margin (neutral point is 2" behind the wing training edge).

My micrometer measures the 3/32" rubber direct from FAI Model Supply as .095" and an average 36" piece of this rubber I weighed at 2.277 grams. When I strip tan super sport rubber to .098" by my micrometer measure, a 36" piece weighs about 2.34 grams and when I strip to .090" a 36" piece weighs 2.19 grams. The 3/32" (or .095") rubber I tested is 7/2011 vintage and the .090" and .098" were both from the 11/2013 batch. The loop length for the motors tested was 14 3/8" for both the .095" and the .098" motor (the .095" was cut a little short and weighed 1.90 grams, lubed with o-rings) and 15 1/8" for the .090" motor; the .098 and .090 motors weighed 1.95 grams each, lubed with o-rings.

I had thought that the .098" motor would be the most promising so I flew this one first.
* Low-power test flights:
* 450 turns (.30 in oz torque), altitude 8', duration = 43 seconds
* 750 turns (.55 in oz max torque backed off 75 turns to .38 in oz), altitude 12', duration = 1:28.5
* "Full power" flights:
* 1,425 turns (1.1 in oz max torque backed off 210 turns to .35 in oz), altitude = multiple ceiling hits, tangled with basket ball goal support and broke wing post tissue tube off motor stick resulting in spin-in from 20', duration 1:59.0, turns remaining unknown
* 1,425 turns (1.05 in oz max torque backed off 270 turns to .30 in oz), altitude 22', duration = 2:35.0, turns remaining 60

.095" motor:
* Similar low-power test flights as with .098" rubber
* "Full power"
* 1,620 turns (1.2 in oz max torque backed off 315 turns to .35 in oz), altitude 21', duration 2:38.0, turns remaining 113

.090" motor:
* "Full power"
* 1,620 turns (1.2 in oz max torque backed off 240 turns to .30 in oz), altitude 18', duration = 2:30.0, turns remaining 240
* 1,620 turns (1.2 in oz max torque backed off 225 turns to .35 in oz), altitude 20', duration = 2;40.0, turns remaining 255
* 1,620 turns (1.2 in oz max torque backed off 195 turns to .40 in oz), altitude 22', duration = 2:54.0, turns remaining = slipped out of my hand
* 1,620 turns; tried winding one more turn on the winder and torque jumped quickly to 1.4 in oz, so backed-off immediately ( 1.2 in oz max torque backed off 180 turns to .42 in oz), altitude 24' 6" resulting in one touch against an air duct and 3' loss in altitude and quick recovery, duration = 3:02.0, turns remaining 255

The .090" motor was rested about 15 minutes between the 2nd and 3rd flight and also 15 minutes between the 3rd and 4th flight. No motors showed any sign of abrasion or nicking from winding. Maybe I could have wound harder.

Recovery from contact with the ceiling was excellent, just a quick dip of about 1' and smoothly starting to circle again with maybe 3' loss of altitude in total. I tried to progress to optimum torque for the site gradually in order to have all flights be "no touch". As the notes above show, I didn't succeed with this strategy for all flights. No attempt was made to optimize the propeller, the propeller was an out of the box stock "flaring" Ikara as shown in my earlier picture. I measured the pitch of this propeller at about 14", with a little excess pitch at blade tips.

One of my objectives with this flying session was to try to create results that would allow me to evaluate tan super sport rubber against better rubber like Bill Gowen used in his flights (earlier post on this thread) (all I own is tan super sport). Of course, it's pretty difficult to do this as the airplanes are different and the propellers are different and there is a world of difference between my skill and experience and Bill's. However, maybe you could compare my 2:54.0 no-touch flight at altitude = 21' - 22' to Bill's no-touch flights and this might be a ball park difference between good tan II rubber and tan ss rubber (again, factoring in my lower skill level and the different propeller). I will be constructing a copy of Bill's first propeller in this thread to continue the test/rubber comparison next weekend (maybe).

http://scioly.org/phpBB3/download/file. ... iew&id=465


Hope this data is helpful.

Brian T.
AMA since 1972 (off and on)
NFFS also for a very long time (again, off and on)

[calvin102111]

Merabeth,

Here is a detailed set of testing notes that i wrote for a demonstration test of the 2015 rules Wright Stuff airplane. I've also attached a picture of my 2015 demo airplaneWright Stuff 2014 Own Design 2.jpg:

Here are my flight test results. My site is 23' 6" from the floor to the lowest obstruction (multiple 3' round air vents projecting from the ductwork) and is the size of one basketball court with about 20' extra along one side for pull-out bleachers. Air is fairly calm as the HVAC systems are shut off this time of year on the weekends. Once I had the airplane decalage trimmed-out per procedures on Bill Gowen's plan, I tested what i am calling .098", .095" and .090" tan super sport rubber. I made no alteration to my initial center of gravity (1.5" behind the wing training edge) as I wanted to fly with the designed 15% static stability margin (neutral point is 2" behind the wing training edge).

My micrometer measures the 3/32" rubber direct from FAI Model Supply as .095" and an average 36" piece of this rubber I weighed at 2.277 grams. When I strip tan super sport rubber to .098" by my micrometer measure, a 36" piece weighs about 2.34 grams and when I strip to .090" a 36" piece weighs 2.19 grams. The 3/32" (or .095") rubber I tested is 7/2011 vintage and the .090" and .098" were both from the 11/2013 batch. The loop length for the motors tested was 14 3/8" for both the .095" and the .098" motor (the .095" was cut a little short and weighed 1.90 grams, lubed with o-rings) and 15 1/8" for the .090" motor; the .098 and .090 motors weighed 1.95 grams each, lubed with o-rings.

I had thought that the .098" motor would be the most promising so I flew this one first.
* Low-power test flights:
* 450 turns (.30 in oz torque), altitude 8', duration = 43 seconds
* 750 turns (.55 in oz max torque backed off 75 turns to .38 in oz), altitude 12', duration = 1:28.5
* "Full power" flights:
* 1,425 turns (1.1 in oz max torque backed off 210 turns to .35 in oz), altitude = multiple ceiling hits, tangled with basket ball goal support and broke wing post tissue tube off motor stick resulting in spin-in from 20', duration 1:59.0, turns remaining unknown
* 1,425 turns (1.05 in oz max torque backed off 270 turns to .30 in oz), altitude 22', duration = 2:35.0, turns remaining 60

.095" motor:
* Similar low-power test flights as with .098" rubber
* "Full power"
* 1,620 turns (1.2 in oz max torque backed off 315 turns to .35 in oz), altitude 21', duration 2:38.0, turns remaining 113

.090" motor:
* "Full power"
* 1,620 turns (1.2 in oz max torque backed off 240 turns to .30 in oz), altitude 18', duration = 2:30.0, turns remaining 240
* 1,620 turns (1.2 in oz max torque backed off 225 turns to .35 in oz), altitude 20', duration = 2;40.0, turns remaining 255
* 1,620 turns (1.2 in oz max torque backed off 195 turns to .40 in oz), altitude 22', duration = 2:54.0, turns remaining = slipped out of my hand
* 1,620 turns; tried winding one more turn on the winder and torque jumped quickly to 1.4 in oz, so backed-off immediately ( 1.2 in oz max torque backed off 180 turns to .42 in oz), altitude 24' 6" resulting in one touch against an air duct and 3' loss in altitude and quick recovery, duration = 3:02.0, turns remaining 255

The .090" motor was rested about 15 minutes between the 2nd and 3rd flight and also 15 minutes between the 3rd and 4th flight. No motors showed any sign of abrasion or nicking from winding. Maybe I could have wound harder.

Recovery from contact with the ceiling was excellent, just a quick dip of about 1' and smoothly starting to circle again with maybe 3' loss of altitude in total. I tried to progress to optimum torque for the site gradually in order to have all flights be "no touch". As the notes above show, I didn't succeed with this strategy for all flights. No attempt was made to optimize the propeller, the propeller was an out of the box stock "flaring" Ikara as shown in my earlier picture. I measured the pitch of this propeller at about 14", with a little excess pitch at blade tips.

One of my objectives with this flying session was to try to create results that would allow me to evaluate tan super sport rubber against better rubber like Bill Gowen used in his flights (earlier post on this thread) (all I own is tan super sport). Of course, it's pretty difficult to do this as the airplanes are different and the propellers are different and there is a world of difference between my skill and experience and Bill's. However, maybe you could compare my 2:54.0 no-touch flight at altitude = 21' - 22' to Bill's no-touch flights and this might be a ball park difference between good tan II rubber and tan ss rubber (again, factoring in my lower skill level and the different propeller). I will be constructing a copy of Bill's first propeller in this thread to continue the test/rubber comparison next weekend (maybe).

http://scioly.org/phpBB3/download/file. ... iew&id=465


Hope this data is helpful.

Brian T.
AMA since 1972 (off and on)
NFFS also for a very long time (again, off and on)

Might I ask, how are you getting the covering on the wings so tight, and how are you making it fit so smoothly onto the plane? Every time I've done it, it always ends up baggy and sloppy.

[bjt4888]

Calvin102111,

Covering is supported by a frame, 3M77 glue is sprayed lightly onto the wing/stabilizer, etc and the parts are then flipped glue side down and pressed gently onto the frame supported covering. After running a finger gently around the wing/stab, etc. outline to be sure that the glue is bonding all the way around, the flying surface is trimmed carefully from the frame supported covering using a new razor blade.

I believe that there is an earlier post to this wiki with Joshua Finn's video of this process.

Brian T.

[Kyle_Guo]

So the thinner rubber was better with the propeller (pitch remained the same through all trials?) ?

[bjt4888]

Yes. In the above testing example, we began with rubber that we were pretty sure was too thick for the particular propeller pitch. As thinner and thinner rubber was tested, launch torque was able to be increased while overall climb height was below the gym rafters and duration increased. In later tests, we increased prop pitch a few degrees and started using a true flaring propeller. The final result for one of my teams was a flight of 3:46 in a 21.5 ft ceiling gym, which won thm the Michigan State Championship. This team employed a very organized and analytical approach and tested alot.

Brian T.

[jander14indoor]

Might I ask, how are you getting the covering on the wings so tight, and how are you making it fit so smoothly onto the plane? Every time I've done it, it always ends up baggy and sloppy.

Note, the covering should NOT be tight, it WILL warp the frames on these light planes. A little looseness or wrinkling won't hurt anything.

The method Brian T. pointed two is specifically designed NOT to have the covering tight. Though it will probably be smoother. Some of this is experience too.

But key is don't sweat it TOO much, unless you are flopping around more than say twice the curve in your wing ribs it isn't a big problem.

Jeff Anderson
Livonia, MI

[calvin102111]

Might I ask, how are you getting the covering on the wings so tight, and how are you making it fit so smoothly onto the plane? Every time I've done it, it always ends up baggy and sloppy.

Note, the covering should NOT be tight, it WILL warp the frames on these light planes. A little looseness or wrinkling won't hurt anything.

The method Brian T. pointed two is specifically designed NOT to have the covering tight. Though it will probably be smoother. Some of this is experience too.

But key is don't sweat it TOO much, unless you are flopping around more than say twice the curve in your wing ribs it isn't a big problem.

Jeff Anderson
Livonia, MI

That's what I figured. I threw together a plane last night using this method, and it got a nice 1:20 flight off of 500 winds. The problem that I was having was that my covering was far too loose, and was creating significant amounts of drag, hence why I was trying to make it tighter/smoother. Thanks for all the help!