Instructions for building plane without kit?

[Kyle_Guo]

Kyle,

Let's start by getting more information. I believe that I understand from your previous posts that you now have the wing LE 4.5" back from the nose and the CG is at 1.5" from the sing TE. If this is not correct, please reply with these measurements.

Now please describe your 50 second flight. How many turns did you put in? What was the torque reading with these turns? Was this with the .065" rubber? How long was the rubber loop you used for this flight? What does it weigh? Does the weight include two black rubber o-rings? Did you backoff any turns before launch? If so, how many and what was the resulting launch torque? Describe the character of this flight. Here's an example of a good description of the character of a flight you might have experienced: launched 3 ft from the floor, climbed in 25 ft diameter circles, climb was smooth and not excessively banked, no noticeable stalling during the climb, climbed to 6 ft from the floor in the first circle, reached 12 ft from the floor in a total of three circles, and flight duration at this point was 30 seconds, began descending from this point and descended in three circles to land at 50 seconds, no noticeable stalling during descent. Describe your actual flight in this manner as best as you can remember.

Did you remove the motor at the end of the flight and record the remaining turns?

A 1.5 gram motor (weighed with two black rubber o-rings) of .0625" or .065" rubber can be wound to at least 1.4 in oz before it breaks. I may have misquoted or averaged the turn capability of the rubber previously. A 1.5 gram (actually 1.42 gram as the o-rings weigh .08 grams per pair) .065" motor (which is about .043 g/in) will probably take about 2,560 turns before breaking and can safely take 90% of these turns, or about 2,295 turns for SO competition.

Let's discuss rubber, winding, decalage angle and left wing washout after you supply the info in my questions above.

Brian T.

The LE is 4 5/8" back, and the CG is 1/2" front the TE. I can adjust the CG by shifting the clay (which is at 1/2" front of TE because whenever I moved it to the front to make it 1.5", the plane would dive and I would get single digit times, due to inadequate wash-in probably) My 50-second flight was not exactly the best it could have been. It climbed slowly with very slight stalls from about 4 feet in a light push until about 15 or so feet (took maybe 2-3 turns) and then I had a small turn circle (10-20 feet diameter) The turns resulted in small erratic shifts in directions instead of a smooth transition (maybe a 20 degree shift each time?) probably because the turn was too small. The plane stayed at that height, refusing to climb higher. Towards 2/3 way done, the stalling was worse and the plane slowly dropped and dropped until it grasped the ground and the plane stopped (in 4-6 turns) I put in 1400 turns and the torque reading was 0.30-0.32 in-oz. This was with 0.065 rubber. The rubber loop was 18"-18 1/2" in relaxed state and It weighed 1.48g- 1.49g (the scale read it differently many times, didn't know which was the right weight) I had only 1 O-ring because I could hook it without it and it was a waste of weight in my opinion. I did not back off any turns because my plane will probably never be at the 20 feet height it should cruise at. I cannot remember the exact turns but It probably got 2 feet from each turn and got up to 10-15 feet, then slowly went down with each stall bringing it 1-2 ft closer to the ground. I didn't know the exact amount of turns because it's hard for me to count turns accurately but im thinking I only used half of my winds because A LOT of winds were left. Enough for another flight that will be shorter because of less torque. I didn't know it could be wound that high becuase when I wind it never exceeds 0.40 in-oz. I guess I used old bands because when I tried to break them, they broke at 0.4 in-oz. I will be redo-ing a test to break a loop so I can better understand and use more of what the rubber can provide in order to get higher flights.

[bjt4888]

Kyle,

Very good information. Diagnosing will be challenging via wiki. If i could handle the airplane we would have it figured out in five minutes. I need a few more bits of info.

What is the wing incidence? Give me the length of the front wing post from top edge of motor stick to bottom of LE and the length of the rear wing post from top edge of motor stick to bottom edge of TE. Make these measurements with the wing posts pushed into the tubes the same distance as when you were flying it.

When you mentioned in an earlier post that you shimmed the stabilizer LE, what do you mean? Describe exactly. It looks from the picture you posted that the stabilizer is attached below the carbon rod (tube?) tailboom. If this is true, then are you saying that there is a shim between the top edge of the stabilizer LE and the tailboom? If so, how thick is the shim?

Brian T.

[Kyle_Guo]

Kyle,

Very good information. Diagnosing will be challenging via wiki. If i could handle the airplane we would have it figured out in five minutes. I need a few more bits of info.

What is the wing incidence? Give me the length of the front wing post from top edge of motor stick to bottom of LE and the length of the rear wing post from top edge of motor stick to bottom edge of TE. Make these measurements with the wing posts pushed into the tubes the same distance as when you were flying it.

When you mentioned in an earlier post that you shimmed the stabilizer LE, what do you mean? Describe exactly. It looks from the picture you posted that the stabilizer is attached below the carbon rod (tube?) tailboom. If this is true, then are you saying that there is a shim between the top edge of the stabilizer LE and the tailboom? If so, how thick is the shim?

Brian T.

The measurement for the amount of penetration for LE post from the top of the MS is 3/16" and the length of the TE post penetration is 5/16". The length of both posts are 2 6/16". I mean. there is a main CF rod that serves as the tail boom. The horizontal stabilizer is glued onto the rod with a 1/16 thick tiny shim piece put under the leading edge, raising it a little. Yes. The shim is put under the LE, glued to both the rod and the stab so that the LE is raised by how tall the shim is (1/16") Does this mean I have to increase the incidence by 1/16" in the wing to compensate for the incidence in the stab?

Should I make a video of a flight with 1400 winds in the current condition and post it here? I can test on Tuesday and make the video and post it on Tuesday night. That may help you. I'll also add more defined pictures so you can observe the plane itself.

[bjt4888]

Kyle,

A video of a flight would help. I think that I will need to take pictures of one of my airplanes to help communicate the wing incidence measurement. I am not sure, but I think that you are communicating that the wing incidence is zero degrees (both wing posts the same length as measured per my last post description.

I see that you have posted questions about solving your winding issues. You must solve the incidence, decalage, CG and washout issues before anything can be done related to winding issues.

Brian T

[Kyle_Guo]

No, I'm saying that the posts are the same length, but they penetrate into the plastic tubing to different lengths. I stated the penetration length into the tubing. Just subtract that from the post length and you get the length over the MS.(not in the tubing)

[bjt4888]

Kyle,

So the wing incidence is 2/16", which equals 1/8". This wing incidence amount creates 1.67 degrees of positive wing incidence angle (inverse Sin of .125/4.3).

Is the tailboom exactly in line with and parallel to the bottom or top edge of the fuselage?

What amount of wing incidence is recommended by the kit instructions?

Brian T.

[Kyle_Guo]

Kyle,

So the wing incidence is 2/16", which equals 1/8". This wing incidence amount creates 1.67 degrees of positive wing incidence angle (inverse Sin of .125/4.3).

Is the tailboom exactly in line with and parallel to the bottom or top edge of the fuselage?

What amount of wing incidence is recommended by the kit instructions?

Brian T.

The tailboom is parallel with the top of the MS. There is a 3 degree left offset. The kit recommends the LE to be 1/4" taller than the TE but that stalled way more for me so I gradually decreased incidence.

[bjt4888]

Kyle,

Good job verifying the tailboom.

First let's define some terminology. I believe (based upon over 50 year of doing this) that you need to move the wing incidence angle back to 1/4" and move the CG forward to about 1.5" forward of the wing TE. Move the CG forward first by shifting the clay as far forward as possible. If this doesn't get the CG to 1.5" fwd of the TE, shift the wing back in 1/4" increments, checking the CG with each shift, till you are at 1.5" ahead of the TE.

Currently, you are flying with 0.58 degrees of decalage and with the CG behind the Neutral Point. The very low amount of decalage angle is why the airplane sort of trims out with the CG so far back. Decalage angle is the difference (meaning = subtract) between the wing incidence angle and the stabilizer incidence angle. The wing set at 1/8" incidence measurement is creating a 1.67 degree wing incidence angle. The stabilizer at 1/16" incidence measurement is creating a positive (meaning leading edge up relative to trailing edge of the stab) is creating a 1.085 degree incidence angle.

Your current decalage angle is 1.67 - 1.085 = 0.585 degrees. This airplane needs between 2.0 and 3.0 degrees of decalage. Your current settings of .058 degrees of decalage and CG behind NP will result in a high degree of instability and erratic flight behavior. This may explain the strange shifting you see during the turn.

Again, as I mentioned before, the settings above are a starting point. You will need to fine-tune by test flying. Use my previous recommendations for fin-tuning and removing stall.

To answer a previous question; yes you need about 1/16" to 1/18" of left wing washin. See the kit directions for recommendations for creating the washin. All other flying surfaces must be completely flat (even a 1/16" twist in one half of the stabilizer or in one of the winglets must be corrected). You can correct slight warps by heating the wood by breathing on it, or very slightly wetting it, and bending at a very localized spot, usually bending 3x or 4x more than you want to correct, and holding for about one or two minutes. This bending method should help straighten any inadvertent warps out of other flying surfaces.

Please make a checklist out of this email and checkoff each recommendation and do them all. Doing a portion of what I recommend will not give you a portion of success. This is what makes this such a great science experiment. Lot's of things to measure and adjust correctly and lots of data to collect and verify in order to achieve success.

Brian T.

[Kyle_Guo]

"Finally, you need the angle of attack of the left wing to be slightly higher than the right wing. This is called wash in where the tip of a wing is twisted to a slightly higher angle of attack than the root (center) of the wing. If your tip angle of attack is less than at the root its called washout. So, build the right wing flat and the left wing so the tip of the leading edge is raised about 1/8 inch higher than the trailing edge. This will require you to crack the front spar so it can bend at the root and reglue it." - jander14indoor
Should I just do that and make the LE of the left part of the wing tilted up so that the LE is 1/16 taller? (measuring from the end of the LE to the end of the TE) The FF kits this year do not address how to create wash-in. They told you to make the wing completely straight and there would be a natural warp that would help the flight, not naming it or telling you how to make it if your wing was actually just flat. I will be putting all the clay at the nose and making the CG 1.5" front of TE. If this all works, the plane will not dive directly for the ground when I wind more than 1400 winds.

[bjt4888]

Kyle,

1/8" left wing washin is a good starting point.

Be sure to increase the wing incidence to 1/4" also.

Reread my previous posts regarding fine tuning CG and wing incidence.

Also reread my previous posts regarding winding, back off turns and launch torque.

Brian T