Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[Hugh Wiedman]

Birdseed definitely something wonky going on there, agree with the others that you'll need to do some investigation. I understand that it did this with the gyro off, correct?, so you can obviously rule that issue out. Not sure that it had anything to do with the elevator control rods, but I will say that I got my Mig just as they came out with the upgrade package. Servos looked good, but I had already bought the ProModeler DS150's so I used those instead, however, I used the excellent aluminum servo control horn and their upgraded control rods. Before I even got a chance to maiden it, some idiot (wonder who that was ) knocked something off a higher shelf in my hangar which impacted one of the horizontal stabilizers. Wasn't all that heavy and did zero marks on the foam & paint of the elevator, but the control rod bent severely. The DS150's can not be moved like cheaper servos when not on and the impact was born completely by the control rod. Bent it back, but felt it actually bent way too easily, so swapped it out for the Hangar 9 4 1/2" Titanium 4-40 rods I had purchased before seeing the upgrade package. Now they're rock solid with absolutely no play. Doesn't take much elevator at a reasonable speed to change orientation on this bird so I'm wondering if the control rods are bending or if there is too much play in the linkage. I know that even the original rods inserted inside a carbon fiber tube are stiffer than the upgraded rods but that titanium rod ain't bending no way no how. Probably out in left field here, but just a thought. Haven't heard of anyone with issues on the Mig with the upgrade package so most likely something else.

[Evan D]

Sounds like you have a good plan.

You probably have used chokes before. The ferrous rings (usually green) on the lead from many ESCs to the receiver.

[Birdseed]

Gliderguy,
Ill get some pics of my radio install tomorrow. However I’m using the powerbox core and i didn’t get any low signal warnings. I’ve also got the elevator set to “hold” in the event of a failsafe. I had a total of 16 frame losses during the 3rd flight so I don’t think that’s the issue. Having said all that, the receiver is in the pocket beside the rearmost battery and one of the two aerials is parallel and attached to the lower plywood battery plate. That is sub optimal, so after this experience, I’m going to make some changes regardless.
Ill take your suggestion and do additional range checks at different angles.
I’m not using RF chokes. Have to admit in 20 yrs of RC flying I’ve never used them, and have no knowledge of them.
It doesn’t give me a warm rosy feeling that the elevator servo leads ( and rudder) run parallel to the power cables to the ESC. However, if there was interference from the ESC, having it affect both elevators at the same time seems unlikely.

I’ve the latest mig 29 kit version, so with larger more outboard set servos, with a metal servo horn and heavy duty hardware. There’s a bit more vertical play in the Clevis than normal-eg the servo arm isn’t as thick as the clevis is, but I don’t think this is giving any play.

My plan therefore is to
1) Do the suggested range checks, then
2) move the receiver to the forward most battery compartment.
3) Bypass the blue box and have a channel for each flap and aileron to allow easier adjustment.
4) Adjust my CC BEC from 5.1V to 6V
5) re install the original BEC and use that to feed the blue box to control the retracts and lights.( I undertand they take up to 5.5V whereas the servos can take 6V)
6) adjust the wingtips to give them the 3mm reflex discussed in other threads.
7) set flaps to normal up position
8) Have aileron reflex set as an option on another switch.
9) Have much more elevator expo than I had before
10) Next time I fly it, fly it in much smoother conditions!

[Birdseed]

Xviper,
Thanks for your comments. You’re absolutely right, it did seem to happen when just levelling the wings. Ill double check there isn’t any odd coupling going on.
I don’t have thrust vectoring so thats not a factor.
What i will do is take the “ reflex” out of the flaps, and see how it performs. I’m certainly not discounting your suggestion that the flaps/ailerons being raised doesn’t cause a dive until its banked over.

[GliderGuy]

https://youtu.be/yiEtDOK8Wls

Not sure why there isn’t a preview attached…

Something is WRONG! I would not fly again until you sort it out. Please post photos of your radio set-up and antenna placement.

Does your radio gear report frame holds or frame losses? There is nothing about the bird that would make it behave like that. The MiG-29 just doesn’t do that (unless you fly fast with flaps down with weak servos).

Nothing in your set-up is out of the ordinary. Lots of folks are set up like yours is. The reflex ailerons and flaps will actually tend to hold the nose up. Take it from a full scale high performance glider pilot who uses reflex flaps all the time (but NOT for landing…it increases the stall speed too much).

Have someone take the MiG away and hold it up. Manipulate the controls through a predetermined pattern with the EDFs on. Try different attitudes in relationship to the transmitter (won’t be easy to do). Does the control movement violate the predetermined pattern? You gotta sort out the radio issue. It will cause a crash….most probably.

Are you using RF chokes? Search the forum and read/learn about them. I had a few uncommanded loss of control events (crashes) on other EDF birds before I started using them. I have had NONE since.

Solve the RADIO PROBLEM before you fly again. Know that the MiG airframe normally doesn’t do the stuff your video is showing.

Consider yourself VERY lucky! You might not get away with it again.

-GG

PS - A final thought…are you using heavy duty hardware to drive the full flying stabilizers? If not….pushrods might be bending under load.

[xviper]

https://youtu.be/yiEtDOK8Wls

Not sure why there isn’t a preview attached…

In all cases where the plane suddenly lost altitude, it seemed like it happened either just as you banked it or right after you banked it and then tried to level the roll axis. I can't tell if you have the thrust vectoring units on the plane. When you are on the ground and you move the sticks to simulate a mild bank like when it was in the air, do any other control surfaces react when they weren't supposed to? I'm just wondering if there is some kind of coupling going on. IE, bank the plane, then the elevators go "down". It doesn't look like it was going all that fast, so can't say it was due to air flow doing something weird to the elevators as we saw when this plane first appeared in Taiwan. The flap down thing was discussed quite a bit in those days as having some affect on the elevators when going fairly fast, but I did several flights at speeds while activating 1/2 and full flaps and mine never dove at all and that was before I installed the TV nozzles. I also don't think your CG had anything to do with the nose dive. The only thing you've got going on that mine doesn't, is the "UP" incident on your ailerons and flaps. Maybe take that out and test fly it again but try to have some altitude if you can. As on one of my old sailplanes where I dialed in UP flaps on a switch, it would lose altitude rapidly but that's with a different kind of wing. Some sailplane guys like to use UP flaps for landing instead of DOWN flaps for landing as it requires a higher angle of attack, which slow the thing down in a more controlled way (sorta like wing spoilers) rather than regular flaps where there is more of a tendency to stall unexpectedly. On this Mig, perhaps a little UP on the flaps/ailerons don't cause a dive till it's bank over a bit.

[Birdseed]

https://youtu.be/yiEtDOK8Wls

Not sure why there isn’t a preview attached…

[Hugh Wiedman]

I maidened my mig 29 yesterday, and managed to get in three flights.

As you can see in the below vid

So the question is, is the models diving behaviour a result of a fwd CG, or am I experiencing the mig’s dreaded nose diving tendency-despite elevator servos being vastly over torqued?

For some reason I'm not seeing the attached video. Maybe my settings, but have always been able to open videos in the past. By chance did you forget to attach it?

[Turbinefancy]

Thanks redfordc! I think it’s a common dream among all rc flyers to shrink down and pilot from the cockpit of our own jet and warbird models. With head-tracking FPV, it’s achievable at least visually. I think FPV should be more aptly called “Fighter Pilot View” but that’s just my opinion

[Birdseed]

I maidened my mig 29 yesterday, and managed to get in three flights.

I used Zeee 5200 mah cells and i swapped out the standard elevator servos for savox 1261MG servos which are rated at 15kg/208oz at 6V

My CG is a 1cm behind the manual recommendation, and ailerons raised so that the lower edge of the aileron lines up with the top of the wing. The flap is level with the aileron. I haven’t raised the ends of the wings as some people have done. Stab position is as per the manual.

Flight 1- without any pylons or missiles. Bit of aileron trim required but no elevator trim required at all. Very pleasant flight, but felt like it wanted to make an uncommanded dive on a couple of occasions, and that was without flaps being deployed.

Flight 2 and 3 were with pylons and missiles fitted, and i tried to set up the igyro. However i quickly turned it off. As you can see in the below vid, there were three episodes where it dived towards the ground. Each time i managed to save it. The end of the vid of the approaches, more than likely shows a PIO as the model was a bit quick and my elevator dual rate was set to 80 percent (as per the manual) and 30 percent expo.




So the question is, is the models diving behaviour a result of a fwd CG, or am I experiencing the mig’s dreaded nose diving tendency-despite elevator servos being vastly over torqued?

https://youtu.be/yiEtDOK8Wls

[radfordc]

Man, that is some excellent FPV flying. It completely immerses you in the role of "pilot" of a jet fighter.

[Turbinefancy]

Excellent flights as usual Airguardian!

Some of us are slow on the sticks by nature, no playback slowdown required. Sharing a flight in which I took the MiG up to altitude to catch a second sunset, checking out the mountain ranges with head-tracking FPV, swoop down to do some lazy acro to wind down the day. Love the Mig-29

[Airguardian]

Glorious slow-mo footage is glorious!

[locharrow]

"Here is a video of my gear door , landing light mock up testing."


T33...your garage is far too tidy..........

[xviper]

Hardly any of those things. It's been a while since I was active here, and I instantly remember your unhelpful, unresponsive, pedantic and often-idiotic replies. When you would say stuff that was comically wrong, you'd just move the goalposts or obfuscate and change the subject. Let's just agree that if ever I ask a question, I'm specifically NOT asking you. Fair enough?

Guaranteed!

[Shaun Evans]

Impatient, demanding AND snotty. And you think you got voted off the island.

Hardly any of those things. It's been a while since I was active here, and I instantly remember your unhelpful, unresponsive, pedantic and often-idiotic replies. When you would say stuff that was comically wrong, you'd just move the goalposts or obfuscate and change the subject. Let's just agree that if ever I ask a question, I'm specifically NOT asking you. Fair enough?

[xviper]

Haha,

Oh how I've missed your lucid, thoughtful and illuminating contributions, lol. This is the 'be careful what you wish for' response. I think I prefer the silence.....

Impatient, demanding AND snotty. And you think you got voted off the island.

[Shaun Evans]

You sound a little perturbed and a bit annoyed that nobody responded. Not sure to which point you are referring to ........................... your EDF units or that noone said anything about the Hitecs. If it was about the EDFs that you listed on RC Groups, I'm not surprised. You didn't provide a link to make it easier for any interested parties to go check it out. Instead, you want people to go over there and hunt for it. I hate RC Groups and I go there only if I have a need to.
If you are referring to the Hitecs, this has been discussed in this thread many times. All that you needed to do was to put in a search within this thread and you would have found all kinds of stuff about it. It's an old topic and I think people are tired of talking about it, especially when it's all posted before.

Haha,

Oh how I've missed your lucid, thoughtful and illuminating contributions, lol. This is the 'be careful what you wish for' response. I think I prefer the silence.....

[xviper]

Hi Fellas!

I'm about to start building my second one for T-power. I don't need these EDF units, so they're on RCGroups if anyone wants some of these new. Also, this kit came with the 'upgraded' servos for the stabs. Are these any good? How do they compare to the Hitec D85's? Thanks!

Dang, NADA, huh?

Well alrighty then, lol...

You sound a little perturbed and a bit annoyed that nobody responded. Not sure to which point you are referring to ........................... your EDF units or that noone said anything about the Hitecs. If it was about the EDFs that you listed on RC Groups, I'm not surprised. You didn't provide a link to make it easier for any interested parties to go check it out. Instead, you want people to go over there and hunt for it. I hate RC Groups and I go there only if I have a need to.
If you are referring to the Hitecs, this has been discussed in this thread many times. All that you needed to do was to put in a search within this thread and you would have found all kinds of stuff about it. It's an old topic and I think people are tired of talking about it, especially when it's all posted before.

[Shaun Evans]

Well alrighty then, lol...