problems with Cybird

[luc]

Well, I can't get this thing fly...
It is rather light (280g with 2S2P Pusion 830)
It flaps wings, goes up(sort of) but as soon as I try to turn, it falls down in a spin and goes heavily on mother earth. The pinion gears of the up/down servo have already been replaced but this is a rather poor quality servo, I will replace it by an hitec 81 MG . Still, it will not solve my problem...CG is 8.5cm from leading edge, wings are aligned, no problem with gearbox or bent shaft....I am puzzled....(note that I have a dozen planes around, heli,turbines, pylon planes,....)

[MartinL]

There are alot of things can go wrong with this bird. I got mine flying really
well until I landed abit hard and broke the spar. Since then I can never
get it back to that previous flying setup. I reckon if u repair the wing too
much the flex is diff so it tends to go over to one side and the rudder cannot
work effectively, also the alignment of the flapper bars to the pinion, if out
of position it also tuck over. This is one VERY FRUSTRATING bird to trim and
fly. I now have to repair it every time I fly, the more repair the worst it
becomes :( I hope Sunny can improve the design and make more friendly
to fly.

Anyone other fliers out there to comment???

[luc]

Thx for your honnest comment. Well I fly pylon racers at 120mph+, do any plane aerobatics you want, started helis...but this bird is really difficult to handle....First thing I will put this hitec 81 MG which should have been there from the very first, then I will give it a serious try, and if I can't manage to fly ok with it, I will get rid of it...:(

[Matthew Cotten]

Sounds like you need weight in the nose,try a 1/2oz led weight in the nose.Matt

[luc]

I know flight symptoms look like an aft CG, but 8.5cm from LE, that's what was said initially, and what I have. Isn't it good?

[Matthew Cotten]

Gosh,sounds good to me.Thats strange it doesn't fly right.
I am done with ornithopters,kinda a novelty item and a crowd pleaser but not for me.I have two of them, one is shipping out tomorrow to its new owner,not sure if I will keep the other.Not an exciting toy what so ever. Matt

[DuncanRigby]

"See the Bird", "Be the Bird".
Not everyone can Master the way of the Ornithopter.

[Matthew Cotten]

Smarta** :D (joking of course)

[Chronister]

The problem described at the start of this thread is most likely caused by improper elevator trim. When the Cybird is near a stall it will behave as described. You need to adjust the elevator trim on your transmitter so more forward speed is attained and then the Cybird will maneuver correctly. It's true that a damaged and repaired Cybird may not fly correctly. First though you should make sure the metal bars the wings attach to are perfectly straight. Also make sure the cranks are synchronized. See the manual for additional information on this. You may need to buy new wings as a last resort. If you have additional questions about troubleshooting or trim feel free to contact me directly at nathan at ornithopter dot org.

[luc]

well, thx for the input
wings are new (I even have an extra set), wheels are aligned, tail is 10° up at neutral....I will correct the CG a bit, change this @¤[# servo by the hitec, and re-test...always give a second chance (normal, due to the investment)...

[Sunny]

Dear Luc and Martin,

I am very sorry for bothering you by Cybird.

I have tried to help you to fly Cybird, but you feel the difficulties to fly it. Moreover, I think that your Cybirds have some troubles.

Though I have tried to fix the problems by my comments, I have not found the ways to do so in online.

Therefore, I am suggesting that you send your Cybird to me and I return it with repaired.

If you sen it by DHL with our account number, you don't have to pay the shipping charge. We will pay some money for it, but I am sure that I can solve your problem. And I will report your problems in detail in this forum after repairing. I expect that this report will be helpful for understanding Cybird.

I worry if other customers may request me to fix theirs, but I believe that they will understand my situation for this case.

I hope that you accept my suggestion.

Thank you for your buying Cybird and I am sorry for your troubles by Cybird.

[Tom in Cincy]

Luc, I have a scratch built Kestrel. I started with an ornithopter that was out way out of trim. First question. When you first launch can you get it to climb out on a straight path?
It will never fly correctly until it can do this with very little input, Maybe some up elevator.
Tom

[luc]

Sunny
Thx for your offer, I will still give it another try when I get the new servo, as explained...if I can't succeed I will honor your proposal.

Tom
Yes it climbed a bit, but problem comes when I try to turn...this thing does not glide and falls heavily. I have also advanced the CG and will revert here after test...

[Tom in Cincy]

Ok Luc.
The bird should climb out in a pretty straight line and gain 20 meters of altitude fairly quickly. If the wing sails are creating uneven thrust it will tend to turn in one direction and will climb very poorly, stall and crash. Rudder will be almost totally ineffective. The winds must be very calm when first trimming out the bird.Very calm conditions shows trim problems more clearly. I know you are a good pilot. There is a problem with the cybird right now.
Tom

[Chronister]

The Cybird will behave differently from the Kestrel because it has very little average dihedral. That makes the Cybird more maneuverable and more efficient than the Kestrel. It also makes it more sensitive to proper trim. The problem Luc describes is unique to the Cybird and quite different from the Park Hawk or Kestrel wanting to turn because of wing asymmetry.

If the wing is OK this problem is usually caused by one of three things: 1. incorrect elevator trim, leading to a stall. 2. bent stroke stem. 3. gears not synchronized properly.

I've also heard about people having to change the CG but I'm skeptical of this. The Cybird is 100% made of manufactured materials and the CG cannot vary unless you mount your receiver and esc in funny places. The receiver should be just above the elevator servo and your esc should be at the motor. One should not be too quick to conclude that the CG must be moved. It's much better to deal with the elevator trim issue instead and you will be amazed at what a difference it makes.

[MartinL]

"See the Bird", "Be the Bird".
Not everyone can Master the way of the Ornithopter.

I agree with Duncan...Ornithopter is not like fixed wing or heli flying...
u can be a real expert but still cannot master the flapper...
I am like Luc..I fly every RC but the bird beat me:(

Unlike fixed wing u can adjust the trim and continuing flying, flapping
bird every parts has to be coordinate like a ballerina.. So u have
to tinker with it and be patient.

I had 3 10+ minutes flight and enjoyed it...I am abit of a scrouge when
come to replacement parts so I fix and make do, that is why mine never
flew the same. My wings has more than 1/2 dozen fixed all over and I
believe that is my problem. It is crazy to replace wing after every crash.

A way to get this bird more controllable is to have independent drive for each wing, this way u can mix in the flapping motion with the tail and get rid
of this uncontrolled side way dive. ...how about that Sunny?????

[Sunny]

At first, I thank Luc, Martin and Nathan for your deep attention to Cybird. Your comments are very helpful for our improving Cybird and our understamding the customers though they can be embarrassing me.

I think that the difficulties of flying Cybird come from the lack of understanding of the characteristics of Cybird.

I know that Cybird is sensitive to initial setting. For reducing the troubles of customers and giving the information as much as we can, a CD which contains the movies of flight has been given to customers. But, this action is insufficient in understanding customers. We will find the ways to do so.

The suggestions by Martin are good ones. Unfortunately, our technology is unable to keep up with his ideas yet. But, we will do our best to solve the troubles.

I think that Nathan fully understand Cybird though I did not see his flight. I expect that he make customers understand Cybird.

I also thank Luc and Martin for your enthusiasm for new products.

[Zettl]

I also experienced the uncontrolled side way dives several times with my Cybird. It is unbelievable how fast the bird falls, if it falls: I bet a stone released from the same height would hit the ground the same time with the Cybird. Very little time to react and to decide which of the contradicting instructions in the manual to follow:
1- fully raising the tail wing and sufficiently reducing wing flapping speed or
2- raising the tail wing and increasing the wing flapping speed quickly

While watching Cybird behaviour during its fall (Quote from manual: "is the nose of Cybird starting to look down" or is it in an "unstable motion (nose up & down)") to decide what to do, in my agony doing both because the first did not help, the awful sound of blunt impact finishes off that flying day again with frustration. Always something is broken.

A typical flight scenario: after the start phase at some hight, I reduce flapping speed power from 80% to 60%, which looks and sounds healthy and maintains height. Just like in the videos.
Then I initiate smooth turns to cruise around. I do fly with a 15 degree raised tail wing, which I raise a bit while giving a smooth left/right command and leave a second or two raised after the left/right command is put back to straight. The bird reacts with delay, but this is normal. It is in this cruising phase when the side way death dive happens, usually initiated by a smooth turn command.

I have no explanation why this happes and how to deal with it.

The flying conditions are mostly a little windy, sometimes mixed with light thermals. I do hear from time to time some very short radio disturbances (motor sound stops for appox. 1/4 s) and observe as a result some instability of the Cybird, but this is not critical and does not correlate with the side way death dive.

Any recommendations?

[Sunny]

Thank you very much for the comments about your experiences.

I think that you are familiar with the flight pattern of Cybird. And you use the same method as mine in order to prevent Cybird from the instability.

It is important to prevent Cybird from instability. Most instability comes when turning. The instability is related to the angle of attack. Cybird make little lift by flapping without angle of attack. The tilt of tail wing is needed for turning, and the tilt reduces the frontal area of tail wing. This make its head down. If the angle of attack is low, the lift can be directed to ground. This is why Cybird fall down unbelievably. Therefore, it is important to make the head of Cybird up when flying. And it is better to raise up the tail wing when turning.

As for short radio disturbances, it can occur when you see the tail because of short disapperance of its antenna. But, as you said, the radio recovers after short time. The manufacturer of receiver recommend that the trouble reduces if the end of attenna attaches to the body shell and the attanna becomes a circle. And this disturbance does not be shown in 72MHz frequencies because 72Mhz wave is stronger than 40MHz (I think that you live in Germany and use 40MHz).

Thank you for your kindness.

[MartinL]

. The tilt of tail wing is needed for turning, and the tilt reduces the frontal area of tail wing. This make its head down. If the angle of attack is low, the lift can be directed to ground. This is why Cybird fall down unbelievably. Therefore, it is important to make the head of Cybird up when flying. And it is better to raise up the tail wing when turning. .

What I cant understand is why the side over when the bird has already completed the turn and ALREADY straighten up. Cutting the power did not help, the only way I can get it to fly again is to quickly get into a STRAIGHT glide mode and when it just about to hit mother earth start full flapping ..
I have managed to get out of trouble a few times this way but it will happen again...cant be successful all the time :( The high torque side over is the main problem. DO u think by mixing 10% up elevator to rudder will help??? I will try this next flight.

I Flew it today with the elevator mix..it does help. I managed some good flight, it did crash later into bituman and broke the metal gear. Now I need to order some replacement parts.

Has anyone in the US flew a Cybird at one of your big Fly-in??

I have a idea and will try it later to improve the roll...I will install another servo with a long arm ..I want to bow the leading edge by tieing a kelvar string from the servo arm to the wing tip. So by pulling up the wing tip from the right will..I hope reduces the lift from the right making it roll right. This is a KISS (keep it simple S..approach) no moving parts. The strong pull motion might tilt the bird sideway too???

[luc]

Btw, I mixed 10% elevator with rudder from the start accoring to what i read...didn't help that much....
i just received my hitec 81MG and installed it.
Here is how it shows:
gws Rx is at the bottom and the red device is the jeti esc, on top of my 2S 830 lipo. CG is around 8.5cm behind LE.
can't fly today; tomorrow raining most likely. I will post my future tries.
Note that I took out the green plate behind the motor which fried and replaced it by some condensers.

[Zettl]

@sunny: Thank you for your fast reply. By now I have accepted that my properly set up Cybird can dive away sideways at any time without prior warning. Whether this is a design issue or is triggered by short radio outages or gusts - fact is it happens and it happens fast.

My main concern is to find an approach on how to save the bird fast when it dives down from medium heights of 15-20 metres. The manual recommends low flying heights for beginners. Observed time-to-impact is 2-3 seconds. A stone would drop in 2 seconds from this height.

My observation is that when Cybird suddenly dives away sideways for the first 5 metres or so, instantly fully raising the tail wing does not show any effect. A theory could be that the tail wing is simply not in the air flow on a sideway dive, so the postion doesn't matter.

That leaves me with the remaining second until impact: motor on or off or inbetween to get back into a stable flying position?

The manual says motor off for minimum damage, but I can't accept that a common flight instability of the Cybird automatically leads to a crash with damage each time.

Below my Cybird with Dymond Digi 22 (D20) ESC under the motor and ACT Pico4 35 MHz receiver. Transmitter is a JR X-3810.

Dymond ESC (6g): http://shop.modellhobby.de/modellhobby/index.php?ktg=90
ACT receiver (5g): http://www.acteurope.de/html/pico_4up_v3_fm-empfanger.html
JR transmitter: http://www.modelflight.com.au/rc_model_radio_control/jr_propo_x-3810_rc_control.htm

.

[massimo]

Hi to all,
Hi Sunny Kim,

Sunny Kim is one person much kind . It has had with me a beautifulst behavior.
But also I have I usual problems with my Cybird P2 and I do not succeed to turn to right and on the left. Also I have activated the mix and soon I will give you my test.
I would want to give a council dear Sunny Kim: Why you do not construct a wing easy to repair? :(I task that is better to construct a wing with the carbon tubes/rods that they can be replaced easy without to use the glue for attack they.


Thanks!


I ask you forgiveness for my ugly English :(



Best Regards

[Zettl]

While I'm at uploading images: here is my cardboard alignment gauge to doublecheck for the 15 degree tail wing setting at neutral postion of the radio control.
This could be included in the kit.

[Sunny]

Thank you all the comments about Cybird.

As for the instability when turing, the main reason is the stiffness of the carbon rod located at the leading edge of main wing. If the rod at the right side of main wing is more flexible than the one at the left side, the wing will show the instability when turning right. Though the balance is made by a paper clip, the instability can be seen in turning. You can see the flexibleness when take off. The flexible rod will show more larger displacement at the wing tip.

However, because all the main wings have been tested, you don't worry about the instablity. But, if the wing is repaired, it can show the instability because of the change of the flexibleness.

The instability can come from the metal drive gears in the front of gear box. Cybird has a tendency to turn left because of the metal drive gears. In order to balance it, we use two methods. One is to attach a paper clip on the right leading edge. The other is in the meatal gears. We fix the position of the metal gears as follows.
- At the horizontal position during down stroke, the right wing should be lower than the left wing by a half teeth. If the horizontal position during down stroke is made, the right wing should be higher than the left wing by a half teeth.

As for wing construction, I am sorry that we have made it to repair difficultly. The design concept of Cybird was a light (safe), a bird-like and a long flying one. For these requirements, we concluded that the wing should be light, and we choose the construction of wing with using the glue. We tried to make wings as similar as the one of Skybird, but we concluded that the way of Skybird is hard to satisfy our requirements.

As for the cardboard for tail wing, I appreciate your suggestion. I will consider it.

As for mixing up 10% elevator, because our basic model of transmitter made in GWS has the function, I have no experience. But I think that it is good to stable turning.

In case of the mode 2 transmitter, I think that it may be some difficult to make turning because the transmitter is set by having the both functions of up-down and left-right of tail wing in one stick. A mode 1 transmitter can control the two function individually by different stick.

As for recovering from the crash, I will upload a movie in the website which shows the moments. I expect that I can upload it in Friday. After finishing it, I will let you know it by writing an article in this forum.

I have received many requests as yours from Korean customers for about one years, and I have solved them because I have been able to see their Cybird and I have repaired them in our factory. In case of oversea custumers, I have felt some difficulties to solve the troubles. But, Because of the reports from customers, I can improve Cybird. I will do my best to satisfy my customers.

[Sunny]

I took a video movies about recovering Cybird from instability today.

Because the companion which is in charge of our homepage will be in business trip until this Wednesday or Thursday, I expect that I can upload the movie in our website this Thursday or Friday.

If anyone want to get it in advance, please let me know your e-mail address. I will send an e-mail which contains the link of zip file (4.8MByte) in the webhard. The real size of movie after unzipping is 15MByte, and I made recovery actions twice in the 2-minute flight.

I hope that this movie will be helpful for a good flight.

[Zettl]

Your last postings were very good, Sunny!
They give background information which could explain the problems of my Cybird:

a)
My left wing was broken and I used for repair a carbon rod which was 0,1mm smaller than the original (1,3 mm instead of 1,4 mm original). Although I did a weight-loaded bending test to confirm nearly-equal strenghts of the new rod compared to the original one, the new and thinner one was still a little weaker (maybe 10% higher deflection under heavy weight load). I argued this change would be less invasive to the flexibility balance than gluing a parallel rod at the broken point. As a result the repaired left wing is a little softer under heavy load. With normal eye sight, however, there is no visible difference of wing tip deflection in stationary flapping tests. If there is one, it is below 10%.

b)
My metal gears were set half a tooth opposite to your recommendation. It is a 50:50 game. It should be mentioned in the manual that it is not possible - due to asymmetric design of the flapping mechanism - to have exactly the shown 180 degree alignment on both the upstroke and downstroke. One is always off a bit.

c)
I like left turns.

Combing all this might be an explantion for the observed high degree of instability.

Which paper clip setting do you recommed for compensation of a little more flexible left wing?

How do you perform the final tests of your factory wings?

Have you flown yourself a repaired wing? What is the best method to repair a broken leading edge? It should always break in the transition from the tube to the rod, as here is the highest stress incontinuity.

I'd like to see the "How to safe Cybird from crash"-tutorial in advance, please. Please use the method when you click on my name ("Send email to Zettl").
Thank you!

[Sunny]

I am happy that my comments are helpful for you.

Instable wings have a tendency that the instability is incresed in higher flapping frequency. Therefore, it is another way to reduce the instability to make its flapping speed lowered when turning.

I answer your questions as follow.

Which paper clip setting do you recommed for compensation of a little more flexible left wing?
=> I am sorry that I have not found the way to compensate the stiffness of carbon rod. The stiffness is different from the balancing. From flight test, we sort out instable wings. The amount is about 5%.
We are using the instability wing as a practice one by spliting into two pieces and taping a fine one with another fine one if you take it from other wing.

How do you perform the final tests of your factory wings?
=> In case of full set or KIT1, we installed to the body.
In case of KIT2, KIT3 (no receiver) or spare parts, we check the performance of wings with some Cybirds for flight test. Therefore, the wings in KIT2, KIT3 or spare parts should be made balanced. But as all the performance was checked, the change of the location of a paper clib will be small.
The requirements for passing test are as follows.
- balancing by a paper clip
- climb rate : over 30m in 30 seconds
- Minimum altitude : 50m
- gliding lock should be operated
- Instability check by 180~360 degrees turning to left and right
- control distance (receiver) : over 150m
Normally, the flnal flight time for passing is 2~3minutes, but the total test time per one Cybird is 5~10 minutes because of making some trials for balancing and confirmation.

Have you flown yourself a repaired wing? What is the best method to repair a broken leading edge? It should always break in the transition from the tube to the rod, as here is the highest stress incontinuity.
=> Of course, we have repaired the broken wings for many Korean customers. We can repair all the type of breakage.
If a carbon tube at the leading edge is split at the junction with carbon rod, a 2nd plastic fixture is used which is on the carbon tube and plays a role of connecting the carbon bones of leading edge and the thin carbon rods. We have put two pieces of 2nd fixture in the extra bag and in the wing set of spare part since this March. In my experiences, this repaired wing shows a same performance with a clean one.
If diagonal carbon or thin carbon is broken, I change the broken one to new one because it is easy to change new one.
But, if the carbon rod at the leading edge is broken, it is better to split into two piece and tape a clean one with another clean one if you take it from other wing.

I'd like to see the "How to safe Cybird from crash"-tutorial in advance, please. Please use the method when you click on my name ("Send email to Zettl").
=> As I have to send the link of the movie in the website of www.webhard.co.kr, I need your e-mail address.

Martin pointed out that a diagram in the kit is needed to show the flapper bar position. Thank you. I will consider it.

I attach two pictures. One is about flapper bar shape at horizontal position during down stroke. You can see that right flapper bar (left in front view) is some lower (by a half teeth) than the other.

The other picture is about repaired wing by 2nd plastic fixture in case of split tube.

[smasher]

Sunny: I am also ready to maiden my cybird, but these posts, have delayed it please email me the video also..slopez@neo.rr.com...thanks

[luc]

with such a surname,...you are pushing your luck... :D

I will try again my cybird this week-end... :confused:

[smasher]

just a user name not how i fly. but thanks for the kind words..

[Zettl]

@sunny: You write << At the horizontal position during down stroke, the right wing should be lower than the left wing by a half teeth. If the horizontal position during down stroke is made, the right wing should be higher than the left wing by a half teeth.>>

After reading it again it confuses me.
In the downstroke at horizontal position: the right wing should be lower or higher?

Please clarify. A picture depicting your point would be perfect. Thank you.

[Sunny]

Sunny: I am also ready to maiden my cybird, but these posts, have delayed it please email me the video also..slopez@neo.rr.com...thanks

Thank you for your attention to Cybird.

I sent an e-mail to you.

However, I edited my last post with adding two pictures about flapper bar position and repairing wing by 2nd plastic fixture. Please see it again.

[Zettl]

Thank you, Sunny!

Now we know the right wing should be set lower during downstroke (just half a tooth).
We also learned that this setting counteracts a natural left tendency, same as the paper clip on the right wing.

With above settings done, neutral rudder and no wind, Cybird should fly straight. If it doesn't, we move the paper clip according to the manual.

If we observe stalls only on a specific turn direction, we know that the inner wing is too soft. To verify, we watch out for different wing tip displacements (softer means more displacement) when holding the Cybird in the hand and flapping.

A too soft wing could result from an undetected carbon tube/rod split.
A too hard wing could result from a repair activity.

If we observe stalls on every turn direction, we were either too slow (tail wing raised too much) or had the nose down (tail wing raised too little).

Here is how I would summarize your stall recovery movie:
If we experience a stall, we immediately stop flapping, which will result in a V-position of the wings and will stabilize the bird during a fast decent. If it looks stabilized, we start flapping again.
We will not be scared by the fast rate of decent.
We will just pray that we had enough height.

Sunny: could above be your words, i.e. is the summary so far correct?

[smasher]

Sunny: I got the video...thanks...

[Sunny]

Thank you for your summary.

You are my best student. :D

I correct something in your post.

(1) To verify, we watch out for different wing tip displacements (softer means more displacement) when holding the Cybird in the hand and flapping.
=> I think that it is hard to verify the instability by watching out when holding the Cybird in the hand and flapping. You can guess the posibility of its instability when take-off by watching out the displacement, and can see the instability exactly in turning. It is hard to change this phrase as a new expression because I have to say that the instability can be known exactly by making Cybird turning.

(2) If we observe stalls on every turn direction, we were either too slow (tail wing raised too much) or had the nose down (tail wing raised too little).
=> If you observe stalls on either (normally(over 95%) the instability is seen in only one direction) turn direction, the way to recover the stall is to reduce or stop the flapping speed and had the nose up (tail wing make fully raised up) at the same time. And the instability increase as the flapping speed go higher.
The reduced flight speed by a high tail wing can make it instable in high flapping speed. But, in low flapping speed, the tail wing is better to be raised up.
And, I have observed that the bent shaft of metal drive gear induces the instability. Sometimes, broken tail wing carbon rod can do that because it cannot make the head up.
In my experience, the instability result from the main wing mostly (over 95%).
Therefore, I think that it is better to say that " If we observe stalls on either turn direction, we were either too slow in high flapping speed (tail wing raised too much in high flapping speed ), had the nose down (tail wing raised too little) or there are some problem in your wing (mostly main wing) or gear box".

(3) If we experience a stall, we immediately stop flapping, which will result in a V-position of the wings and will stabilize the bird during a fast decent. If it looks stabilized, we start flapping again.
=> It is important not only to stop flapping when stall, but also to makt the tali wing fully rased up at the same time because the fully rased up let the head up.
When it looks stabilized, it is better to start falpping in low falpping speed at first as seen in the movie that I sent to you because the high flapping speed can induce the instability in high falling speed. The low flapping speed reduces the falling speed because the main wing play a role of parachute. After you confirm its recovery, you can increase its flapping speed.
Therefore, I would like to change the phrease as "If we experience a stall, we immediately stop flapping and make the tail wing fully raised up at the same time, which will result in a V-position of the wings and will stabilize the bird during a fast decent. If it looks stabilized, we start falpping in low falpping speed at first and increase the flapping after confirming its recovery".

(4) We will just pray that we had enough height.
=> I recommend that it is better not to fly Cybird with instable wing. The instable wing can break the servo gears and gear box.
Therefore, I suggest that "We will not fly Cybird with a instable wing and should ask some helps by writing a post in this forum or send an email to Sunny Kim".

[Zettl]

<<You are my best student.>>

But obviously the worst pilot. Or the one with the least luck.

Thank you very much for your review, Sunny!

What is your thought on the brake setting of the ESC (electronic speed controller)?

I used to have "brake on" for good gliding lock, but changed to "brake off" because I argued the flapping mechanism gets softer on impact, thus less damage.

I even removed the gliding lock piece recently so the flapping mechanism can't possibly lock hard on impact. Of course I don't attempt gliding now. I just don't want to permanently destroy my Cybird.

Still I damaged my wing again with this setup (diagonal inner tube split heavily and plastic gear torn). Unfortunately there is no separate plastic bag with repair material in the new wing package I purchased from Nathan recently.

Another question concerns the undervoltage cut-off functionality of the Cybird.
According to the manual that function is both integrated in your receiver/ESC-combination and in your lithium battery. Is that correct? Can you please tell the trigger voltages?

[Sunny]

As for brake of ESC, because I have never used the function until now, I an sorry that I don't have something to recommend you. But, in my experience, I don't feel the need of brake because gliding lock stops the wing in proper position for good gliding though the possibility is low.
If you stop the flapping the wing suddenly, the possiblity of gliding is 20~25%. But when gilding is fail (thw wing is V-shaped), start the wing flapping slowly until it goes to the position of gliding (under horizon) and stop it. It need some practise, but I think that you can do it easily if you are familiar with Cybird.

The gliding is a basic, but simpler flight pattent than other patterns. Therefore, I recommend that gliding is better to be tried when you are good at flying Cybird.

Because the plastic fixture for repairing is for only a split tube at the leading edge, you should find another ways to fix the split diagonal tube.
One way to repair a split tube is to wrap it with a string tightly. You also have to glue it with carbon rod by cyano. A pair of plastic gears for gear box are included in the extra bag which is in the carrier box, but servo gears have to be bought.

As for undervoltage cut-off, lithium battery must not be fully discharged different from Nicd batteries. If do so, some gas is generated in the cell. As well as the gas reduces the life, it can be burnt out during charging. Therefore, in order to use the battery, a protection device is needed. We call it PCM (a small PCB board with some electric parts). PCM is connected with the 2 cells in the package of battery pack, and checks the voltage of the battery pack. If the voltage is under about 4.5, it cut the power of the pack in order to prevent the cells from excessive discharge. If PCM is operated, Cybird cannot fly any more to stop flapping and crash.
In order to prevent Cybird from crashing by PCM, we include a microchip in the receiver which has a program. The program is operated to reduce the falpping speed when the votage is under about 5V. The lowered flapping speed makes Cybird land. After power off, the program is initialized.

Because the performance of battery is lowered in cold condition, Cybird can fly only 1~2 minutes. Because the battery is made warm by this operation, you can fly much more after power off and on. But, total flight time of cold condition (in my experience, under 5 degrees Celsius) will be reduced than warm condition.

The inceased load in gear box (some problems in gear box) can stop the battery because the increased discharge current make the voltage low instantly. You have to check the condition of gear box.

PCM has another function. If the pack is charged in higher voltage than fully charged voltage (8.4~8.5V), PCM is burnt out in order to prevent the battery from burning. In that case, the cells are safe, but PCM has to be replaced with a new one or a new pack to be bought.

I hope that my comments will be helpful for you.

[Zettl]

Thank you, Sunny!

After my last crash I inspected again my metal gears. It was still set according to your instructions (on downstroke right wing a bit low) and did not jump teeth during crash.
When I look at the upstroke postion, however, the left wing is very much obvious lower. This observation is done with new flapping bars. Can you confirm this to be OK, please?

It is now the third flapping bar I loose - and I wished it would be redesigned. Due to the current design, which features a sharp edge exactly in the region of highest mechanical load, it is simply doomed to break at this edge.

Another improvement would be a dedicated overload protection for the flapping mechanism (other than the gears). It would be nice if you would mention the words "friction clutch" and "cheap designed-to-break plastic pushing rods, supplied in dozens" in your next brainstorming session on Cybird improvement.

[Sunny]

Dear Sebastian,

Thank you for your suggestion.

As for the position of wing, I can tell you that the difference at down-stroke + the difference at up-stroke = a tooth. Therefore, I don't understand that down stroke is ok but up stroke is strange. I appreciate if you show the up-stroke and down-stroke by pictures.

We already(in February) improved the flapper bar by changing its material. The old flapper bar is black, but new one is silver-colored. After changing it, I have no report that the flapper bar can break in crash. Could you check it ?

I am sorry that I don't understand what "friction clutch" means. Please explain it to me.

As for "cheap designed-to-break plastic pushing rods, supplied in dozens", I understand that you want a device to absolve the shock to elevator servo in order not to break the servo gears. Is it right ?
If so, we are trying to improve the strength the servo gears by changing the material from plastic to metal. We finished the test. The servo has 2 plastic gears (1st and last gear) and 2 metal gears (2nd and 3rd gear). We conclude that this metal gear is stronger than the previous plastic servo by about 3~5 times. We are negotiating the price with its manufacturer, and I expect that the metal gear can come in June.

I am sure that you can expect improved Cybirds as you want.

[Zettl]

Dear Sunny,

Unfortunately I do not have the silver unbreakable flapper bars, but the black ones (which can be cyano-glued with special preparation). See also the picture of my Cybird earlier in this thread.

For the "friction clutch" see the attached drawing. Two rotating parts unlock when an overload appears. The locking mechanism is spring loaded fricton.

Both ideas were to save the flapping mechanism and wings, not the servo.
The "cheap designed-to-break plastic pushing rods, supplied in dozens" could substitute the aluminum pushing rods, connecting the metal gear with the flapper bars. The plastic part would be designed to break under overload before (!) the flapper bar does or the plasic gears strip. They also preserve the metal gears from bending. Most of the damaging force to the metal gears is induced via the aluminum pushing rods, not via direct impact, if the body shell is used (I always use the body shell).

I imagine you should be able to produce 20 or more breakable plastic rods for the price of 2 aluminum rods and include them all in the Cybird package. Your customers can quickly exchange the rods (no gear box disassembly needed) after crash, they will not experience stripped plastic gears, they will not experience lost C-clips in the field, they will not experience bent metal gears and they will probably have less broken wings. Short: your customers will love you for that change.

[Sunny]

I will forward your ideas to my members, and they will consider them.

Thank you for your ideas.

However, I cannot tell you about the strange position of flapper bar when up-stroke because I cannot see the pictures.

[Zettl]

What is Korean for "coming soon"?

[Sunny]

What is Korean for "coming soon"?

"곧 출시"[Got Chool-See] or "개봉박두"[Ke-Bong-Bak-Doo] (especially for movie). But, it is hard to expree the exact pronunciation in English. You can read the Korean letters different from what they are.

[Zettl]

여보세요, 이것은Sebastian말 감사한다 너를 이다.

[Sunny]

여보세요, 이것은Sebastian말 감사한다 너를 이다.

Thank you very much for your Korean greetings.

Mor exactly, it is better that "여보세요, Sebastian은 당신에게 감사합니다.". This means that "Hello, Sebastian thanks you."

Anyway, I hope that my recommend will be helpful for the flying Cybird. And customers voices have been good for improving Cybird.

[Jerry Rose]

My left wing was broken and I used for repair a carbon rod which was 0,1mm smaller than the original (1,3 mm instead of 1,4 mm original). Although I did a weight-loaded bending test to confirm nearly-equal strenghts of the new rod compared to the original one, the new and thinner one was still a little weaker (maybe 10% higher deflection under heavy weight load).

Hi Zettl. I don't have a Cybird, so this idea may be crazy, but ... consider doing the same repair to the right wing too. Then both wings will have very nearly the same flexibility and strength!

Very minor variations in otherwise identical carbon wing spars can affect the flight of my ornithopter. Some rods have more flex in one direction than another, and must be physically rotated in order to achieve balance.

A 10% difference in deflection between wings such as you describe, would certainly make a huge change in the flight characteristics of your bird.

[Zettl]

Dear Jerry,

you spelled the problem: a small difference in wing tip displacement seems to have a strong impact on Cybirds flight stability. Note the word "impact".

That's why I asked whether Sunny and other pilots (that don't crash with such a scaring continuity as I do) bother flying repaired wings at all.

Well, they do. And they repair just the broken side.

[Sunny]

Dear Jerry,

you spelled the problem: a small difference in wing tip displacement seems to have a strong impact on Cybirds flight stability. Note the word "impact".

That's why I asked whether Sunny and other pilots (that don't crash with such a scaring continuity as I do) bother flying repaired wings at all.

Well, they do. And they repair just the broken side.

Dear Sebastian,

As I worry if some misunderstaning can be arised, I point out that the stiffness of the carbon rod (at leading edge and at diagonal) is important to instability. If a split tube was repaired by string or plastic fixture, the stiffness of carbon tube inlittle affect to the total stiffness because it is enough stiff.

However, if a carbon rod was replaced in a thin one, I think that it can result in instability.

I mean that repaired carbon tube seems not to affect the instability but the changed carbon rod has much possibility to instability if it is not replaced nby same rod.

[Zettl]

Dear Sunny,

in my case I have again a broken diagonal carbon rod. As it is broken it is too short now. It broke off exactly at the end of the tube. As the tube end is reinforced from the last repair, it did not split this time. This is good news and bad news. Better the tube splits and the rod remains intact.

What do you recommend if a diagonal rod is broken and local carbon rod suppliers stock only rods that are 0.1mm thinner (1,3 mm instead of 1,4 mm original)?

I hope there is an alternative to a new wing set.

Link to common German carbon rod sizes: http://wes-technik.de/English/carbon.htm

[Jerry Rose]

... a small difference in wing tip displacement seems to have a strong impact on Cybirds flight stability.

This concern reflects on all ornithopters in general. Those wings are giant propellors, and if one blade of a prop twists a bit more than it's mate, then an imbalance will result. It seems to me that this is the weakest area in an ornithopter, which is to say the area where the repairman must take the greatest care.

You've either got to alter the other wing to match, or get an original replacement spar from Sunny or Chronister. Considering that your spar is changing the design, it cann't perform as well as the original. However, if it was mine, I'd test it with the 1.3 spars and see how it goes. If it is still marginal, remember the original design spars (1.4) are stiffer, and therefore less subject to twist.

[Zettl]

Dear Sunny,

here are two pictures showing my Cybird on
- downstroke (top): right wing bit low, same as your picture
- upstroke (bottom): left wing more lower

It doesn't look like that on yours?
Anybody else reading here please check with their Cybird?

[luc]

I just checked and have exactly the same setup on wings as yours....
I will test mine this week-end with the new servo MG...btw, you didn't change your servo? no problem with this moving potentiometer?

[Zettl]

No problems neither with the servo nor the potentiometer, Luc. Yet. Knock on wood.

[Sunny]

Dear Sunny,

here are two pictures showing my Cybird on
- downstroke (top): right wing bit low, same as your picture
- upstroke (bottom): left wing more lower

It doesn't look like that on yours?
Anybody else reading here please check with their Cybird?

No problem in your gear box. Because the first picture shows that it is almost horizontal, the other is more lower. Your Cybird has a more left turning tendency than usual. Therefore, the paper clip will go outer or 2 clips may be used in right wing in order to balance your main wing.

In order to make the displacement of a half tooth, the metal drive gears has a difference of a half tooth by changing the position of connecting rod (Yellow rod connecting metal drive gear and flapper) in the metal drive gears. This means that the gears are different from each other in detail, and it is better to install metal gears in the side that they should be. Even if a metal drive gear is installed in opposite side, there is no problem because the balance can be made by paper clip(s) in main wing.

[Sunny]

Dear Sunny,

in my case I have again a broken diagonal carbon rod. As it is broken it is too short now. It broke off exactly at the end of the tube. As the tube end is reinforced from the last repair, it did not split this time. This is good news and bad news. Better the tube splits and the rod remains intact.

What do you recommend if a diagonal rod is broken and local carbon rod suppliers stock only rods that are 0.1mm thinner (1,3 mm instead of 1,4 mm original)?

I hope there is an alternative to a new wing set.

Link to common German carbon rod sizes: http://wes-technik.de/English/carbon.htm

I know the German company because I had used its carbon rod during the most of development. And the diagonal rod that I had used is 1.3mm. The rods is some more stiff than the rods that used in Cybird. But, Because the stiffness of rods are different as their manufacturers even with same diameter.

Therefore, the main wing has instability even though you change only the rod, it is better to change the other rod as Mr. Jerry Rose suggested.

If you lived in Korea, I could repair your wing easily.

[Zettl]

Dear Sunny,

<<Because the first picture shows that it is almost horizontal, the other is more lower.>>

I'm still not sure what is the correct setting of the metal gears.
I set the metal gears exactly off half that tooth as you described it and showed in your picture. Both my top picture and your picture from earlier on in this thread show the same amount of hang of the right wing at downstroke. So we have the same setting on the downstroke.

Could you please answer whether your Cybird shows the same setting as in my bottom picture (upstroke postion)? Ideally, you could post a picture of your upstroke position, please.

Could other readers (Nathan?) please check with their Cybirds? Thank you so much!

What is the main objective of the metal gear adjustment?
- to find the most symmetrical setting for both upstroke and downstroke or
- to set the right wing half a tooth low on downstroke.

<<..it is better to change the other rod as Mr. Jerry Rose suggested.>>

I tried 2 German cyano debonders to carefully remove the rods from the wing, both did not work. Instead, they slightly decolored the wing. It doesn't look good. Furthermore, I'm afraid that the acetone ingredients might have weakened the plastic fabric of the wing. How do you remove a glued broken rod from the wing without hurting the fabric?

[Sunny]

I am sorry for confusing you.

Because there is a tolerance in making the holes for connecting rods in metal drive gears, the difference may not be a half tooth. But, (the difference at down-stroke) + (the difference at up-stroke) = a tooth. I mean that this tolerance can be adjusted by a paper clip on main wing. Actually, the displacement in my picture of alignment is about 1/4 tooth.

As for the main objective of the metal gear adjustment, if the flapper alignment is horizonal or higher at down stroke, a paper clip should be moved to outer side of main wing. Because I thought that this was not good in performance (because more power-consumed) and stability, we have applied the method in Cybird.

And if the flapper alignment is lower by over a tooth at down stroke, this is also not good at performance and stability because of dissimmetry in flapping.

The method to detach the rod from a wing is to (1) remove a tape at the end of tube of diagonal bone, (2) just detach the rod from fabric by hand with care (because fabric is thin, it can be torn. If it is torn, you have to just with tapes. But, I worry if you can find a tape which can be attached to the fabric easily and tightly. And it can be bonded tightly at the juction of diagonal bone and thin bones. In that case, you should divide them carefully with a knife), (3) divide the bone from the 5th plastic fixture by hand.(Because the plastic fixture and the carbon rod was attached by cyano, it can be hard to divide the rod from it by hand. If the one side of the section of plastic fixture which the rod is inserted to is scratched by knife, you can detach it more easily. Because ony one side is scratched, the rod can be reattached by cyano after changing a new rod). And it is better to swing the rod repeatedly when pulling it.

The method for dividing the rod and tube is to use a vise. After the rod is grabbed by a vise, pull the tube by hand.

[MartinL]

That alot of hard work..I just cut the broken area and put a solid rod into the tube and CA it

[Zettl]

Dear Sunny,

thank you for the beautiful repair procedure!
I understand you are not using cyano debonder, but simply tear it apart.
Is it essential that the diagonal rod is not glued into the tube? My diagonal rods were tightly wrapped with thin clear tape and then firmly inserted - not glued - into the tube. Was this done by purpose to create some flexibilty at the junction?
As I do not find a tape that sticks nearly as good as your tape to the fabric, would you please mention where to buy it?

Futhermore, would you kindly consider my open questions:
- does your perfect-flying Cybird show the same setting as in my bottom picture (if your picture is 1/4 tooth low, your other side should be 3/4 tooth low)?
- is it good to find the most symmetrical setting for both upstroke and downstroke or to set the right wing half a tooth low on downstroke?

To me, first comes the understanding of the proper mechanical setup, and then, later in flight the paper clip corrections.

Could other readers with perfect-flying Cybirds (Nathan?) please check the extent of flapper bar asymmetry with their birds? Thank you so much!


@Martin: <<I just cut the broken area and put a solid rod into the tube and CA it>>

If you don't replace the whole rod, how do you successfully connect the new rod with the remaining, intact bit of the rod?

[Zettl]

Dear Sunny,


We already (in February) improved the flapper bar by changing its material. The old flapper bar is black, but new one is silver-colored. After changing it, I have no report that the flapper bar can break in crash. Could you check it ?
Coming back to this topic earlier on this thread, I found this picture in the web, showing black flapper bars with black ends. My ends are silver-colored metal. Now I'm not sure whether I have the new "silver-colored" ones or the old "black" ones.

Could you please state whether the new "silver-colored" ones are silver at (1) or (2) or both positions?

Thanks!

[luc]

Well, I too have the old flapper system...
I flew again today, advancing the CG and with the MG hitec 81...
yes it flies, but gliding flat is quite difficult and another thing is difficult is to make it turn where and when you want. Some landings where hard; the pins leave the body easily...
in conclusion, i would say this thing is definitely for an expert, and is very fragile on the wing (btw I got also another broken junction that i repaired later, a bent flapper bar) as it does not glide as a plane (in fact, I consider it as a mix of a plane and an heli).
Improvements should be in wing strength, ability to turn, stability,....
good points imho are motor, gearbox, servo linkages, tail.
I will still insist again....

[MartinL]

[QUOTE=Zettl
@Martin: <<I just cut the broken area and put a solid rod into the tube and CA it>>

If you don't replace the whole rod, how do you successfully connect the new rod with the remaining, intact bit of the rod?[/QUOTE]

I am referring to the splited pop on connector...I insert a solid rod into the
CARBON tube allowing 1/2 " over inside the tube then CA IT.

[Zettl]

Because the companion which is in charge of our homepage will be in business trip until this Wednesday or Thursday, I expect that I can upload the movie in our website this Thursday or Friday.

I hope all of you are well and your companion did not travel by train in North Korea. It is now the third day in a row your website (and presumably your company email web access) is offline. We miss you, Sunny!

Online again?
http://www.cybirdshop.com
http://www.cybird-shop.com
http://www.neuros.co.kr

[Zettl]

Could other readers with perfect-flying Cybirds (Nathan?) please check the extent of flapper bar asymmetry with their birds? Thank you so much!


So far not much response.
Seriously no other readers here?

@Luc: where is your CG now? Where was it before? Which one gave you a more stable feeling? Thanks!

[luc]

CG is now around 8cm behind LE, more stable , but this thing is definitely very sensitive and fragile....so I think I will quit. I still have a brand new wing and spares, so...
anybody wants a nice Cybird PII, drop me a mail....

[Sunny]

Dear Sunny,
thank you for the beautiful repair procedure!
I understand you are not using cyano debonder, but simply tear it apart.
Is it essential that the diagonal rod is not glued into the tube? My diagonal rods were tightly wrapped with thin clear tape and then firmly inserted - not glued - into the tube. Was this done by purpose to create some flexibilty at the junction?
As I do not find a tape that sticks nearly as good as your tape to the fabric, would you please mention where to buy it?

Futhermore, would you kindly consider my open questions:
- does your perfect-flying Cybird show the same setting as in my bottom picture (if your picture is 1/4 tooth low, your other side should be 3/4 tooth low)?
- is it good to find the most symmetrical setting for both upstroke and downstroke or to set the right wing half a tooth low on downstroke?


No, you should glue the rod with the tube by cyano in order that the juction should not be separated when flapping and impact.

The tape wrapping the rod has 3 purposes which are (1) to prevent the carbon rod from being degradated by cyano, (2) to play a role of cushion in flapping and impact, and (3) to make it easy to exchange the rod with new one (it is some easy to separate it from the tube when pulling the rod in vise).

I think that the tape on the fabric seems to be hard to find near you because it is special one.

The symmetric setting of right flapper has been made between 1/4 and 3/4 tooth. If the setting gets out of the range, it can show an instability.

And if the right wing is lower by 1/4 tooth when down stroke, the left wing is lower by 3/4 tooth when up stroke.

This setting is related to the position of paper clip on the wing. If you set 1/2 tooth, the paper clip normally is located in the 3rd section(between the 2nd and 3rd fixture) of the right wing. If 1/4 tooth, most of the paper clip is in the 4th section (between the 3rd and 4th fixture). It took a few months to find this characteristic.

[Sunny]

Dear Sunny,
Coming back to this topic earlier on this thread, I found this picture in the web, showing black flapper bars with black ends. My ends are silver-colored metal. Now I'm not sure whether I have the new "silver-colored" ones or the old "black" ones.
Could you please state whether the new "silver-colored" ones are silver at (1) or (2) or both positions?
Thanks!

I attach a picture which shows the new flapper bar.

[Sunny]

I hope all of you are well and your companion did not travel by train in North Korea. It is now the third day in a row your website (and presumably your company email web access) is offline. We miss you, Sunny!

Online again?
http://www.cybirdshop.com
http://www.cybird-shop.com
http://www.neuros.co.kr

our website and e-mail system was out of order during weekend. We are trying to correct the problems. I am sorry for bothering you.

And I received Martin's Cybird today, and I will check it and make a report about it soon.

[MartinL]

Sunny...Good to hear u r well...When I could not contact u I was abit concern..
not good news of the train accident..even through it is up north.

Come on Luc..u cant give up now..RC diehard like the challenge...
especially when u read about the guy building the 10.5" RC ornithorper.
All we have to do is to tune it :)

[Zettl]

Welcome back Sunny!

> diagonal rod exchange:
Again I'm puzzled: you recommend to glue the rod, but in the same sentence you mention 3 good reasons not to glue.


>tape:

I think that the tape on the fabric seems to be hard to find near you because it is special one.

This is exacty the reason why I asked in the first place. Could you please supply the 3M designation? I will try to find and post an European source for our Cybird community. Without good tape no good wing repair.


>flapper bar:

We already (in February) improved the flapper bar by changing its material. The old flapper bar is black, but new one is silver-colored. After changing it, I have no report that the flapper bar can break in crash. Could you check it ?

I'm sorry to report Cybird broke two of the new silver-colored flapper bars since, as mentioned earlier on this thread. They did break at the earlier described sharp plastic edge in the inner region. I will suppy a picture later. 개봉박두


>different levels of asymmetry:

And if the right wing is lower by 1/4 tooth when down stroke, the left wing is lower by 1/4 tooth when up stroke.

As you can see from my picture at [4] of this thread, this does not hold true for my flapping mechanism.


>how to set metal gears:

- does your perfect-flying Cybird show the same setting as in my bottom picture (if your picture is 1/4 tooth low, your other side should be 3/4 tooth low)?

Am I right when I answer myself this question with "No"?



- is it good to find the most symmetrical setting for both upstroke and downstroke or to set the right wing half a tooth low on downstroke?

Am I right when I answer myself this question with "good to find the most overall symmetrical setting"?

I understand this is different to the recommendation to let the right wing hang by half a tooth on downstroke earlier at [2] in this thread.

[Sunny]

> diagonal rod exchange:
Again I'm puzzled: you recommend to glue the rod, but in the same sentence you mention 3 good reasons not to glue.
=> Because the perimetric section to be glued to tube is larger than that in gluing to fabric, I recommend to wrap the rod with the tape when glueing the rod to tube.

>tape:
This is exacty the reason why I asked in the first place. Could you please supply the 3M designation? I will try to find and post an European source for our Cybird community. Without good tape no good wing repair.
=> I am sorry that I don't know what it is. If you don't find 3M tape, you don't have to use it. The cyano can endure the force by flapping. The purpose of the 3M tape is to prevent it from be seperated by hands and so on.

>flapper bar:
I'm sorry to report Cybird broke two of the new silver-colored flapper bars since, as mentioned earlier on this thread. They did break at the earlier described sharp plastic edge in the inner region. I will suppy a picture later.
=> I look forward to your picture.

>different levels of asymmetry:
As you can see from my picture at [4] of this thread, this does not hold true for my flapping mechanism.
=>I am sorry for my mistake. The second 1/4 is 3/4. I corrected it.
In the pictures of your post (#52 in page 4), the difference at down stroke is 0~1/4 tooth, and the difference at up stroke is 3/4~1 tooth.

There is no contradiction in my recommendation, and it is simple. It is better that the right wing is lower by 1/4~3/4 tooth than the left one when horizontal at down stroke. And the remained balance should be made in main wing by a paper clip.

I hope that you understand me.

[Zettl]

Thank you, Sunny. I'm fine now.
Waiting for your analysis of Martin's Cybird. I hope we can all benefit from the results.
If we manage to improve the original Cybird ahead of Chinese/HK clones, customers would rather buy the more advanced products at Neuros.

In Germany, your web sites are still not available. I observed the outage at late 21.April. Can you currently access it in South Korea?

[Sunny]

Thank you, Sunny. I'm fine now.
Waiting for your analysis of Martin's Cybird. I hope we can all benefit from the results.
If we manage to improve the original Cybird ahead of Chinese/HK clones, customers would rather buy the more advanced products at Neuros.

In Germany, your web sites are still not available. I observed the outage at late 21.April. Can you currently access it in South Korea?

I finished repairing Martin's Cybird, and I am waiting for stopping raining.

I made its pictures before repairing, and I will take movies when flight test. Therefore, I can present a report which is made by msword, and a movie file. These files will be sent to your e-mail by webhard as before because they are large sized.

If anybody want these files except Martin, Sebastian, Luc, please tell me your e-mail address by private message.

As for our website, we have tried to fix it, but failed. Today, we called an expert for the system. Moreover, I have not received any e-mail since yesterday night. Our e-mail system will also be fixed.

I am sorry for bothering you.

[Zettl]

Dear Sunny,

as I read, tomorrow Wednesday should be nice.

Weather at Taejon, South Korea:
http://www.wunderground.com/global/stations/47133.html

[Sunny]

Dear Sunny,

as I read, tomorrow Wednesday should be nice.

Weather at Taejon, South Korea:
http://www.wunderground.com/global/stations/47133.html

Yes, you may be right.

Now, there is no rain in Daejeon, and wind is weaker than in the morning.
I expect that I can make a flight test tomorrow.

In tomorrow's test, the best pilot will fly the Cybird, and I will take movies.

[Zettl]

Dear Sunny,

find attached the broken flapper bar. After having a closer look, the metal is not silver everywhere.

[Sunny]

Dear Sunny,

find attached the broken flapper bar. After having a closer look, the metal is not silver everywhere.

As I saw your picture, I understand your situation.

The flapper bar is the same as siver-colored one because it is thermally treated.

More exactly saying, your metal flapper bar was not broken, but, the plastic flapper was damaged. The plastic flapper can be also broken in the case of impacting near the flapper.

We will try to improve this part.

[Sunny]

I finished the flight test of repaired Cybird of Martin.

I sent my report (857KB) and a movie (27.3MB, 7min. 32sec.) to Martin, Sebastian, Luc, smasher, lebyathan.

And the Cybird was sent to Martin today by EMS.

The conclusion of my report is as follow.

(1) Martin’s Cybird had some problems as follow.
- broken left metal drive gear and 3rd plastic gear
- broken rudder servo’s gear
- broken and repaired bones of main wing
Because of these defects, it had to be repaired in order to fly.

(2) After our repaired, the blue wing has no problem in flying. But, the bird wing has an instability in turning left. This comes from the rigid front bone in right which is repaired by him. Unfortunately, we could not repair the right front bone because he had bonded the rod and tube with strings and cyano.

I hope that these are helpful for your understanding of Cybird.

[Zettl]

We will try to improve this part.

Good! As an engineer, you know the easy method of photoelastic stress analysis. It does not require expensive software and gives you fast results, just using Araldite and polarized sunglasses. I highly recommend you invest a little time here and avoid sharp edges in new designs. I see many other parts on Cybird that exhibit designs, which could be made stronger with less weight. Less weight could also mean cheaper production at high volumes. A stronger product means higher customer satisfaction.

Reading stuff for the interested:
http://www.viseng.com/consult/photo.html

.

[Sunny]

Good! As an engineer, you know the easy method of photoelastic stress analysis. It does not require expensive software and gives you fast results, just using Araldite and polarized sunglasses. I highly recommend you invest a little time here and avoid sharp edges in new designs. I see many other parts on Cybird that exhibit designs, which could be made stronger with less weight. Less weight could also mean cheaper production at high volumes. A stronger product means higher customer satisfaction.

Reading stuff for the interested:
http://www.viseng.com/consult/photo.html

.

Thank you for your comments.

I fully understand you because we have been involved in the turbomachinery such as turbojet, turboshaft, turbofan and turbo compressor for about 10~15 years.

I can tell you that we are improving Cybird in order to satisfy our customers though it may take some time to apply to Cybird.

[MartinL]

Sunny..I have viewed the wmv file and I am impressed with the flying.
It sure sounded like my bird but I can never get that kind of solid flight.
Please advise the angle of the tail setting. The bird looked so easy to
fly in the hand of an expert..I have noticed he bank left and right hard
with the bird wing(bad wing) and it does not tuck into a death dive???
When I bank hard it would have fallen off the sky on the way to the
repair bench.

Your report did not say much other than what you have replaced. Did you
change the CG, I assume the video bird has the complete complement of my
gear. What else did you changed??? The climb rate is exactly the same when
I fly it..I have to cut back otherwise it gets too high very quicky. And when
I glide it down it does not has the same stability as shown in the video.
When I start up from a glide sometime it tucks over.

So according to your report both my wings are flyable. The yellow threads
are kelvar tows..it will never fail at the joint and very light. Most repairs
can be done in 5 minutes. Looking forward to get my bird back in the air..
I hope I can repeat the flight shown on that clip. If I cant most probably
you will not heard from me again :(

I appreciate all your feedback and the free repairs...this is what I call
"fantastic customer support"

[Sunny]

Sunny..I have viewed the wmv file and I am impressed with the flying.
It sure sounded like my bird but I can never get that kind of solid flight.
Please advise the angle of the tail setting. The bird looked so easy to
fly in the hand of an expert..I have noticed he bank left and right hard
with the bird wing(bad wing) and it does not tuck into a death dive???
When I bank hard it would have fallen off the sky on the way to the
repair bench.

Your report did not say much other than what you have replaced. Did you
change the CG, I assume the video bird has the complete complement of my
gear. What else did you changed??? The climb rate is exactly the same when
I fly it..I have to cut back otherwise it gets too high very quicky. And when
I glide it down it does not has the same stability as shown in the video.
When I start up from a glide sometime it tucks over.

So according to your report both my wings are flyable. The yellow threads
are kelvar tows..it will never fail at the joint and very light. Most repairs
can be done in 5 minutes. Looking forward to get my bird back in the air..
I hope I can repeat the flight shown on that clip. If I cant most probably
you will not heard from me again :(

I appreciate all your feedback and the free repairs...this is what I call
"fantastic customer support"

The answer is that he knows the characteriscs of Cybird. He is the best pilot of Cybird, and I have seen his flight even in hard condition such as wind, rain, small space, and so on. If you are trained by him, you would understand Cybird in 10 minutes. When he trains somebody, he use a training cable which is connected two transmitter. The training is very effective.

The instability can be known by the shape of flight. You have to make action in order that Cybird does not go instable.

The main reason of instability is to make its head down. Therefore, you have to study how to do in order not to make its head down.

There are some ways to do so.

1. The basic(initial) setting of tail wing makes become a little high.
If you feel the head of your Cybird near horizontal (nomally the angle of body is about 5~10 degrees in stale flight) When Cybird takes off or cruises, increase the tail angle by moving trimming knob even when it is fliying. You can see the difference of its flight. But if the angle is high, Cybird is hard to go ahead. Therefore, you have to understand its proper angle. The best pilot normally set the angle near 10 degrees, and I use near 15 degrees.

2. Most of the instability occur when turning. When the tail wing tilt in order for turning, Cybird can go down because of the decrease of frontal area of tail wing. In order to prevent it, the tail wing also have to be raised up slightly or near fully. Sometimes, the tail wing go tilt in opposite direction after turning in order to prevent go away to the turning direction. I prefer to remain the tail wing raised up after turning.

3. Another method is to decrease its flapping speed. The instability increase as the flapping is fast. Therefore, I recommend that maximum flapping speed is not used except take-off. You should not use full throttle Even in take-off
before you check its balalce and performance. Cybird can take off even in 80% trottle. We use 60~70% rpm in cruise (level flight).
This is same in turning. If you decrease it to 60~70% before turning and raise up the tail wing, you can do sharp turning with small radius of turning.

4. The only way to recover instability is to stop the flapping and raise up the tail wing fully. If you want to recover it by sustaining its falpping speed, Cybird cannot return you with a good condition. If you want to save your Cybird, you have to "kill"(stop its falpping) it.

I changed only the parts in my report.

As for gliding, When gliding, you should have to control it delicately and make the tail wing raised up. Please see the videos.

I hope that I can hear a good news from you.

[MartinL]

All I can say about my flying...it is just habit/second nature that after a turn u level off at the elevator...just have to break the habit with a ornithorper..keep it up all the time. Your last post really make me see how a fixed wing flyer having problem adjusting. I need to program in rudder/elevator mix and have a long delay to elevator to go back to neutral after rudder is back to neutral. No sure my 9CAP will do that, but my backup MPX3030 will. I have another good look at the flight..a ornithorper fly at an angle of 10-15 deg. all the time. It will be helpful if the design force that angle of flight, then we dont have this death dive problem. It is very difficult to see it properly up high...sometimes I cant tell which way it is heading.

[Zettl]

Dear Sunny,

as Martin and you pointed out already: your "best pilot" is very good. What is his name?

By watching the videos I'm not sure which control layout he uses on his private transmitter. I see his transmitter is not the one supplied in the Cybird package.

Would you please be so kind and indicate - using below terminology from the picture - which function he uses on which gimbal?

Thank you!

.

[Sunny]

Dear Sunny,

as Martin and you pointed out already: your "best pilot" is very good. What is his name?

By watching the videos I'm not sure which control layout he uses on his private transmitter. I see his transmitter is not the one supplied in the Cybird package.

Would you please be so kind and indicate - using below terminology from the picture - which function he uses on which gimbal?

Thank you!

.

His name is Myungwhan Kim who is my senior by one year at the same university and majors in aerospace and combustion as same as mine. He have used "laser4" of Hitec(it was the basic transmitter in P2A) as his transmitter. But, the function is all the same as our current GWS transmitter.

throttle : 3
left or right of tail wing : 4
up(pull) or down(push) of tail wing : 1

[Zettl]

Congrats to Myungwhan for his impressive flight demonstrations!

Concerning the stick layout: what are the pros and cons of having the throttle left (pull = full throttle)?
Thus up/down and left/right of tail wing is on the right stick.
I argue that
- because throttle is to be used to control height it would be more natural to fixed wing pilots (and most helicopter pilots that fly throttle/pitch left)
- helicopter pilots having the swash plate right have set the right stick spring-neutralized to center
- to catch the bird with the right hand it would be better to have the throttle under control with the left hand.

[Sunny]

Congrats to Myungwhan for his impressive flight demonstrations!

Concerning the stick layout: what are the pros and cons of having the throttle left (pull = full throttle)?
Thus up/down and left/right of tail wing is on the right stick.
I argue that
- because throttle is to be used to control height it would be more natural to fixed wing pilots (and most helicopter pilots that fly throttle/pitch left)
- helicopter pilots having the swash plate right have set the right stick spring-neutralized to center
- to catch the bird with the right hand it would be better to have the throttle under control with the left hand.

I am sorry that I don't know the control of helicopter and airplane because I have never control them. But, my stick layout is Mode 1 as same as used in fixed-wing airplanes.

Because the landing of Cybird need a delicate control and I am a righty, it is better that the throttle and left-right control of tail wing are located in right stick. And the catch when landing can be done by left hand, more exactly by left hand, left arm, and chest at the same time.

It is full-throttle to make the throttle stick pushed.

The stick layout is different as the pilots, and I prefer to my layout.

[Zettl]

Dear Sunny,

another thing strikes me and I want to doublecheck if you think this is normal with the Cybird:

The common flapper bar joint pin (steel) has a diameter of 2,95 mm.
The suspending holes in the frame have a much larger inner diameter: 3,45 mm which results in unneccassary play and mushy wing timing. The play here at the pin is equivalent to about 3/4 tooth of metal gear misalignment.

Same with the loose fitting of the pusher rod steel pins in the plastic flapper bars: all this adds to 3 mm of undefined play at the metal end of the flapper bar, which translates to several centimeters of play at the wingtips.

.

[Zettl]

I'd like to share my method of checking for bad friction in the gearbox with others for open discussion.

Observation:
Cybird has an open gearbox, sandgrains and dust will sometimes jam the gears just a little so that the Cybird will still fly but with degraded performance. The feeling is like the battery is weak. The motor will geht hotter than usual.

First, I detached the whole gearbox from the frame, checked for exessive friction in the gearbox, checked for exessive friction in the motor, cleaned and lubed where neccessary and reinstalled everything.

Now, I put the frame on a scale, zero the scale with the frame's weight and then gently press down the flapper bars as illustrated.
The force should be around 3N (300g) for the flapper bars starting to move down if everything is OK.

This method is highly sensitive to any bad friction and measurements of 400-500g indicate alreday some dirt contamination in the gearbox or two plasic gears touching on its flat side (happens after crash).

.

[Zettl]

At [2] of this thread I introduced a cardboard alignment tool to doublecheck for the 15 degree tail wing setting at neutral postion of the radio control.

Now after revising my transmitter trim I see the cybird flies better with 18 degree neutral setting. Thus a one-angle-only adjustment tool is not so helpful when you want to fine-tune angle settings.

I found a far simpler way to check and set the tail wing elevation: simply measure the distance as illustrated and refer to below graph.

.

[Zettl]

The distance is measured on a flat surface with body shell removed. The center of the tail tip was used as reference.

My current settings are 65mm (fully pushed), 145mm (center) and 215mm (fully pulled).
@sunny: can you please verify with your Cybird?

.

[Sunny]

Dear Sunny,

another thing strikes me and I want to doublecheck if you think this is normal with the Cybird:

The common flapper bar joint pin (steel) has a diameter of 2,95 mm.
The suspending holes in the frame have a much larger inner diameter: 3,45 mm which results in unneccassary play and mushy wing timing. The play here at the pin is equivalent to about 3/4 tooth of metal gear misalignment.

Same with the loose fitting of the pusher rod steel pins in the plastic flapper bars: all this adds to 3 mm of undefined play at the metal end of the flapper bar, which translates to several centimeters of play at the wingtips.

.

The pin whose diameter is 2.95mm is designed to fitted to the bearings in the flappers. The larger hole in the frame is just for assembly. The pin should be installed into 4 holes such as ones in 2 flapper, the frame (it's part name is "Bracket_Flapper_Fix"), and front plate of gear box. In easy installation of the pin, we are obliges to make the hole of the frame larger than the pin.

However, this larger hole does not affect the alignment of metal drive gears because the pin is fitted to the holes of the flappers.

The loose fitting of the pusher rod (we call it "connecting rod") steel pins in the plastic flapper bars can affect it, but you don't mind it.

[Sunny]

The distance is measured on a flat surface with body shell removed. The center of the tail tip was used as reference.

My current settings are 65mm (fully pushed), 145mm (center) and 215mm (fully pulled).
@sunny: can you please verify with your Cybird?

.

Your initial angle of tail wing is about 18 degrees.

As I have said, I suggest that the initial tail angle is 10~20 degrees. Our best pilot use the angle near 10 degrees, but I use 15 degrees or so. This comes from the fact that he prefers to dynamic motion (speed) whereas I like a stable flight.

The pilots should invest their times to know the characteristiocs of Cybird as the angle though it will take some times.

Generally, the angle of tail wing is affected by the wind and its main wing.

In strong wind, the angle is better to be set near 10 degrees. But in carm weather, I recommend 15 degrees or 18 degrees as you.

Some main wings has a high lift. In that case, a low angle is ok.

There is no answer to the angle, but a higher angle (near 15 degrees) is good to stability.

[MartinL]

Just to follow up my bird after its round trip back from Korea..I took on Sunny's previous posting advise regarding the tail position, so I mixed in 50% elevator to the rudder(can do with abit more..I still hold abit of up). Flew it yesterday on a calm morning and it flew like a charm..I had 2 flights, I did the following..fast V postion glide, right angle glide..nice and slow and in full control, and inverted V ..the bird did some sort of a spin and recovered nicely. It flew for about 8 minutes and spot landed. The trimming Sunny did made it a better bird. I noticed the following..the bird MUST trim to fly straight and ALWAYS fly the bird at a high angle of attack even on a calm day. If it is slow to turn pull up abit more elevator and apply more trottle. It didnt have the nasty habit I experienced previously.

[Sunny]

Just to follow up my bird after its round trip back from Korea..I took on Sunny's previous posting advise regarding the tail position, so I mixed in 50% elevator to the rudder(can do with abit more..I still hold abit of up). Flew it yesterday on a calm morning and it flew like a charm..I had 2 flights, I did the following..fast V postion glide, right angle glide..nice and slow and in full control, and inverted V ..the bird did some sort of a spin and recovered nicely. It flew for about 8 minutes and spot landed. The trimming Sunny did made it a better bird. I noticed the following..the bird MUST trim to fly straight and ALWAYS fly the bird at a high angle of attack even on a calm day. If it is slow to turn pull up abit more elevator and apply more trottle. It didnt have the nasty habit I experienced previously.

I am happy to hear a good flight from you.

As for tail angle, a higher angle is needed in carm day than in windy days.

I hope that you will have fun with Cybird for a long time.

[Zettl]

First crash of this day, again the wing broken. In lack of a short piece of carbon tubing suitable for the recommended repair method, I used a small brass tubing 3,5x0,5mm to "ring" the bird.

.

[MartinL]

Still crashing!!!! My bird flys normal now..very reliable and stable.Based on similar problems..from what I can see..the only fix I cannot visual is the gear sychronising, as for the others my bird fly in a straight line with no input. My tail has a higher setting. Since it came back from Korea I had 7 flights with full control and landing. Making the bird fly straight is just the clip..concentrate on the flapping synchronizing..there must be a way to set it correctly.

A better way to repair is to use a 2 m rod, file in half and CA upper/and lower and rap carbon or kelvar tows..alot easier and lighter. The brass tube will weigh about 1 or 2 clips!!!! and u will need 2 clips on the good wing to counter balance.

[luc]

too fragile and too twitchy....this has to gain in stability and reliability.
Ifit has to go to Korea each and every time somebody gets one, something is wrong.
the problem is that this thing does not glide easily, but rather falls with some wing breaks not that hard to repair but which destabilize the bird still more...:(

[Zettl]

The brass tube will weigh about 1 or 2 clips!!!!

Don't worry, Martin. The brass is probably lighter than the original carbon repair tube from Neuros: it weighs approx 1/20th of a single paper clip.
Disadvantage: the brass is not so sturdy as the original repair tube. I hope it breaks again at the next crash rather than the rod, which is extremely hard to replace and chances are you permanently destabilize the whole wing.