Instructions for building plane without kit?

[Kyle_Guo]

Here are my notes from today's testing (many typos and errors):

1400 winds, 1 min 2 seconds, about 300 winds left, torque around 0.030, 0.065 rubber, climbed in 3-4 loops, circled few loops, stalled greatly for 5 last loops and landed. Climbed to the point that I was afraid of hitting the supports on the ceiling of the gym (25ft entire height, 20 ft flyable). 20-25 feet circle diameter was very small, used only half the gym width (20 feet or so) The rubber I used was a very heavily used rubber ( flown maybe 30 times with average of 1200 winds each time) will I have to dewind with new rubber to stop it from hitting the supports on the ceiling?


Should the circle be bigger? The plane wasted tons of space and was in no danger or hitting the walls at any point (except the ceiling) I currently have stall so I don't need to move the wing back anymore. Ill look over your comments from before on trimming when I've got the CG right.

[bjt4888]

Kyle,

Actually, you do need to either move the wing back some more. Moving the wing back moves the CG forward and helps remove stall. Or, you could remove about 1/16" of wing incidence to try to remove stall. Don't remove any more than 1/16" though.

Try moving the wing back 1/2" first. If this adjustment doesn't remove the stall, reduce the wing incidence 1/16" in addition to leaving the wing in this more forward position.

Yes, read all of my posts regarding winding, back off and launch torque.

Leave the circle size as it is. It is handy to have a circle size in the 20' - 25' range as some competition sites could be smaller than your gym.

Brian T

[Kyle_Guo]

I was thinking of reducing incidence to remove stall, I'll try moving the CG back 1/2" and test again tomorrow. I've also yet to cut the extra weight off of the plane. Hopefully, when I remove the weight from the MS, it doesn't affect the CG very much. I also think there is too much wash-in as you tell that the left side of the wing is slanted upwards at a point easily and that the LE is closer to 1/4" higher rather than 1/8" higher. I now don't even need to tilt the rudder because of the wash-in, tail offset and stab tilt already give it a 20 ft circle.

[bjt4888]

...Kyle,

Read my post again. I said move the wing back which moves the CG forward. Try it and see.

Brian T

[bjt4888]

Kyle,

Congrats bye the way on the improved flight. If you had wound to 85% maximum turns, which would correspond to about 1.2 in oz and backed off turns to a launch torque your flight would have been about 1:45, or maybe more.

Brian T

[bjt4888]

Kyle,

Also, if the airplane is flying well except for moderate stall, don't change the left wing washin.

As i noted above, the next change to try is tomove the wing back 1/2 inch (which moves the CG forward to cure stall).

Brian T

[Kyle_Guo]

Here are the new observations for the test flights today:

Winds: 1500, torque: 0.32-0.35, Dewinds: none, Incidence: a little more than 1/4 Time: 1:28, Circle Diameter: 25 feet.
Let go of plane, circled 3 times to max height (literally just under the metal supports ~20-25 feet) and circled at max height 4 or 5 times. On 2nd circle, it bumped a support, sending it down 1 ft or so, it climbed back and I thought it was going to hit again, but it didn't. Started to lose altitude at about 50 seconds and plane circled smoothly (one occasional small stall) for 5 times and landed.

I followed your advice of shifting the wing back 1/2" and I adjusted the wing post length (a little more than 1/4") to make it climb just the right amount. Now I'm thinking of shaving off the extra weight and getting launch torque right fo I can get many more winds in at the same max height.

[Kyle_Guo]

I will check for any stalls remaining, then try to get the most winds out of the rubber, then deal with propeller pitch.

[bjt4888]

Kyle,

Good job getting to this point. I'm going to give some hard and fast rules of trimming.

1. Do not adjust climb rate by decreasing wing incidence. Do not adjust climb rate by decreasing wing incidence!
2. Wing incidence for this airplane needs to be at least 3/16" (if the stabilzer is flat and based upon all other setup recommendations i have given you).
3. If you are still stalling and the wing incidence has already been reduced from 1/4" to 3/16", you need to move the CG forward more by moving the wing back. Once trim is close and stall is slight, the wing ahould be moved back in smaller increments like 1/4".
4. Reduce cljmb rate by slightly increasing propeller pitch, maybe about 2 degrees at a time with test flights at each new pitch setting. Get a pitch measuring tool from Freedom Flight Models, they're cheap.
5. Fly at full (85% of breaking turns) every flight, with propee backoff turns to avoid the ceiling. If you are close to the ceiling now using partial winds and launching at 0.30 in oz, wind to 2,200 and backoff to a launch torque of about 0.28 in oz. If this flight is safely under the ceiling, fly at a backoff to 0.30 in oz on the next flight. Let motors rest a least 10 minutes betwen uses and use a new motor every 5th flight.

Brian T

[Kyle_Guo]

Kyle,

Good job getting to this point. I'm going to give some hard and fast rules of trimming.

1. Do not adjust climb rate by decreasing wing incidence. Do not adjust climb rate by decreasing wing incidence!
2. Wing incidence for this airplane needs to be at least 3/16" (if the stabilzer is flat and based upon all other setup recommendations i have given you).
3. If you are still stalling and the wing incidence has already been reduced from 1/4" to 3/16", you need to move the CG forward more by moving the wing back. Once trim is close and stall is slight, the wing ahould be moved back in smaller increments like 1/4".
4. Reduce cljmb rate by slightly increasing propeller pitch, maybe about 2 degrees at a time with test flights at each new pitch setting. Get a pitch measuring tool from Freedom Flight Models, they're cheap.
5. Fly at full (85% of breaking turns) every flight, with propee backoff turns to avoid the ceiling. If you are close to the ceiling now using partial winds and launching at 0.30 in oz, wind to 2,200 and backoff to a launch torque of about 0.28 in oz. If this flight is safely under the ceiling, fly at a backoff to 0.30 in oz on the next flight. Let motors rest a least 10 minutes betwen uses and use a new motor every 5th flight.

Brian T

I have not been decreasing the incidence, I have been increasing it because with the 0.30 in-oz torque at 1/4" it climbs to only 3/4 the gym. My wing incidence is more than 3/16 and will never be anywhere near that. I am not stalling anymore except for the 1 small stall of a few inches on the last loop or in the 10ft height range. I will be moving the wing back slowly until everything is smooth. I am literally at the ceiling using 0.30 in-oz torque with my wing incidence. There is a slight chance that the plane will hit the ceiling but launching from 6" off the ground (I was launching at about 4 feet that time) should help. I already have the prop pitch gauge (thankfully, buying it now it would arrive in 3 weeks and that would be too late). I have maybe 3-4 props so I'll go through some until the pitch is okay. I don't have the best amount of rubber but enough to get me 7 or so motors which means 35 test flights. Take note that the rubber I was using for the 0.30 in-oz flight was decently used (10 flights 1000 wind average) so Maybe a new motor would have to have a 0.28 in-oz torque. I will try this out Thursday and Friday for several hours.