Originally posted by janmb
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Official Freewing MiG-29 Fulcrum Twin 80mm Thread
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Hugh "Wildman" Wiedman
Hangar: FL/FW: Mig 29 "Cobra", A-10 Arctic, F18 Canadian & Tiger Meet, F16 Wild Weasel, F4 Phantom & Blue Angel, 1600 Corsair & Spitfire, Olive B-24, Stinger 90, Red Avanti. Extreme Flight-FW-190 Red Tulip, Slick 60, 60" Extra 300 V2, 62" MXS Heavy Metal, MXS Green, & Demonstrator. FMS-1700mm P-51, Red Bull Corsair. E-Flite-70mm twin SU-30, Beast Bi-Plane 60", P2 Bi-Plane, P-51.
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I visited with my HAM radio guru who put me on to the RF choke idea. Passing along his comments:
The shielding (copper tape, etc.) will be most effective when it is grounded (like to the PCB ground trace). But, regardless it will have some effect when placed between the ESC and servo wires.
To help minimize the potential noise on the servo wires back in that area...
Use the copper (etc.) tape between the ESC and servo wires AND place a clip-on ferrite RF choke on the servo wire back near each servo. (LOL - Saw that one coming.)
The Re-routing room isn’t much back there. May not be enough room to make much difference.
I’m gonna do mine this afternoon.
-GG
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Originally posted by Waconut View PostGG,
Do you have stock in the Ferrite ring companies?
Helps with moving the CG rearward, as an added benefit! And the higher wing loading pushes out the speed where max L/D in the glide is achieved.
-GG
Just kidding!
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Hello,
Originally posted by Firebird View PostWhen i opened the compartment holding the fan and the motor controller, i found both - elevator and rudder servolines - passing freely, directly underneath the controller. I‘m not a electronic expert but i do suspect the motor controller to create a certain electromagnetic noise at midrange powersetting. (...)
So just having the elevator wires near the ESCs is not explaining it. There would need to be other reasons, such as ESC-specific emissions, veryvery long wires, induction from the current in the battery leads that go to the ESCs before it hits the extra capacitors, power loss, ...
Cheers,
Henrik
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Originally posted by GliderGuy View PostI visited with my HAM radio guru who put me on to the RF choke idea. Passing along his comments:
The shielding (copper tape, etc.) will be most effective when it is grounded (like to the PCB ground trace). But, regardless it will have some effect when placed between the ESC and servo wires.
To help minimize the potential noise on the servo wires back in that area...
Use the copper (etc.) tape between the ESC and servo wires AND place a clip-on ferrite RF choke on the servo wire back near each servo. (LOL - Saw that one coming.)
The Re-routing room isn’t much back there. May not be enough room to make much difference.
I’m gonna do mine this afternoon.
-GG
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Hello,
this may be redundant, but as the elevator issue is still not resolved (Does it exist or is it all bad luck and misinterpretation? If it exists, then what is the cause?), I am crossposting this post from me from RCG:
Under the most rearward battery compartment, there is a "snake pit" of wires that go- towards the blue box
- but also directly to the receiver, such as the throttle.
In my case, at least one servo wire was emerging from below the wooden panel improperly, namely it was sandwiched (by the factory) between the frontal end of the wooden panel and the foam. I had to manually pull it out, and it showed stress marks: You can see the effect of the relatively "sharp" edges of the wooden panel onto the servo wire. All three leads of the servo lead have little horizontal cuts, the lower cut being more pronounced than the upper. You can also see the indentation of the foam from the wire on the pictures. The little cuts as seen here look harmless.
However, suppose that the plane flies, the fans emit vibrations, and the edge of the wooden panel actually would saw through the shielding of the servo lead. With bad luck, you could have a short, possibly only temporary while the engines are running and vibrations are strong. This short is on the "active end" of the blue box, i.e. the end from which the control leads go to the control surfaces. Maybe having a short there does cripple / disable the blue box, even temporarily?
This would explain why the telemetry from one of the crash reporters showed good readouts from the receiver (including voltage), because the receiver is "on the other side" of the blue box. It would also explain why throttle response was still there, as the throttle is not routed via the blue box.
Opinions?
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I only placed the “shielding” (aluminum self-adhesive pipe tape I had handy) between the ESC and the servo wire run area. The smallest of the barrel-type clip-on RF chokes fits perfect in the area ahead of the elevator servo. Photo below is prior to tucking it in.
Will it decrease the probability of an incident occurring? Who knows....but it is easy work to accomplish.
-GG
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I cut my battery to ESC wires by about 7". There was no reason for the length especially since I don't use the forward bay.
Originally posted by HK111 View PostHello,
That is an obvious suspicion, and I guess many had it already, too, including myself. However, there are other airplanes, such as the Freewing Su-35 and the Freewing / SebArt MiG-29, where there is a very long central channel between the ducts which contains *every wire* that goes to the back: 2x3 highly AC powered lines going to the fans, plus servo leads for 2 elevators, 2 rudders, and for the TV nozzles. The ESCs sit at the beginning of the channel on top of all these wires, and the elevator and rudder wires go right below the fans, from the central channel to the outside of the fuselage. But neither the Su-35 nor the SebArt ever had the problem that we suspect with the Freewing MiG.
So just having the elevator wires near the ESCs is not explaining it. There would need to be other reasons, such as ESC-specific emissions, veryvery long wires, induction from the current in the battery leads that go to the ESCs before it hits the extra capacitors, power loss, ...
Cheers,
Henrik
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Originally posted by HK111 View PostHello,
this may be redundant, but as the elevator issue is still not resolved (Does it exist or is it all bad luck and misinterpretation? If it exists, then what is the cause?), I am crossposting this post from me from RCG:
Under the most rearward battery compartment, there is a "snake pit" of wires that go- towards the blue box
- but also directly to the receiver, such as the throttle.
In my case, at least one servo wire was emerging from below the wooden panel improperly, namely it was sandwiched (by the factory) between the frontal end of the wooden panel and the foam. I had to manually pull it out, and it showed stress marks: You can see the effect of the relatively "sharp" edges of the wooden panel onto the servo wire. All three leads of the servo lead have little horizontal cuts, the lower cut being more pronounced than the upper. You can also see the indentation of the foam from the wire on the pictures. The little cuts as seen here look harmless.
However, suppose that the plane flies, the fans emit vibrations, and the edge of the wooden panel actually would saw through the shielding of the servo lead. With bad luck, you could have a short, possibly only temporary while the engines are running and vibrations are strong. This short is on the "active end" of the blue box, i.e. the end from which the control leads go to the control surfaces. Maybe having a short there does cripple / disable the blue box, even temporarily?
This would explain why the telemetry from one of the crash reporters showed good readouts from the receiver (including voltage), because the receiver is "on the other side" of the blue box. It would also explain why throttle response was still there, as the throttle is not routed via the blue box.
Opinions?
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Originally posted by mshagg View PostHaving servo wires cohabitating with speed controllers in the ducting isn't exactly a unique trait to this bird is it?
Then again, most of those are probably not running setups as powerful as the MiG-29... and at least on the Su-35, there were ferrite rings on the ESC leads as a stock feature... so there's that. Nothing conclussive of course, but another thing to have in check until further notice I guess :)
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Originally posted by HK111 View PostHello,
That is an obvious suspicion, and I guess many had it already, too, including myself. However, there are other airplanes, such as the Freewing Su-35 and the Freewing / SebArt MiG-29, where there is a very long central channel between the ducts which contains *every wire* that goes to the back: 2x3 highly AC powered lines going to the fans, plus servo leads for 2 elevators, 2 rudders, and for the TV nozzles. The ESCs sit at the beginning of the channel on top of all these wires, and the elevator and rudder wires go right below the fans, from the central channel to the outside of the fuselage. But neither the Su-35 nor the SebArt ever had the problem that we suspect with the Freewing MiG.
So just having the elevator wires near the ESCs is not explaining it. There would need to be other reasons, such as ESC-specific emissions, veryvery long wires, induction from the current in the battery leads that go to the ESCs before it hits the extra capacitors, power loss, ...
Cheers,
Henrik
I'd be inclined to look at the leads from the batteries to the ESCs. These have the highest currents and will be generating large, varying magnetic fields capable of inducing currents in nearby signal level wiring. The three-phase wires from ESC to motors will be largely canceling each other out. IMO, of course.
I'm still more inclined to think there's some aerodynamic explanation, such as elevator blanking, that's only triggered under some, maybe unusual, conditions. There have certainly been instances in full-size aviation where such things happened.
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Originally posted by RudyD54 View PostFor anyone who does what I did and accidentally snaps off the pitot tube in front and needs a new one, the part is the following:
The MiG-29 parts pictures aren't up yet and when I called support they said it came with the nose cone (it does not) and had no idea what "Plastic Nose Cone Part" referred to. I placed an order for both parts which are luckily priced reasonably. The nose cone comes with ONLY the nose cone and the wood piece you glue into it. Plastic nose cone part includes everything attached for 4.49.
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After about a dozen flights with no issues I decided anyway to do my elevator upgrades today. Overall very pleased with how it turned out. Used the F-14 wing swing pushrods with 4-40 safety lock kwik links. Test flights tomorrow. (and yes, I have RF chokes, cap packs, crow in ailerons/flaps, and elevator Y to receiver).
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Would be nice in this modern world to run fiber optic cable to all electronic components in an airplane. No electromagnetic interference. Unfortunately, it would require nano sized fiber to copper conversion to run servos and ESC signal plus receiver wiring. It would solve a lot of issues for sure. Someday....
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Thanks for your feedback!
I just wanted to share the status of rerouting the elevator and rudder servo cables on my mig 29. In order to get as far away as possible from the controller and the long main power and esc control cable i chose to use the way following the maingear control cable. From there i pushed a hole through the foam to lead the cables under the plastic cover of the gearmotor bay. I opened the rear fuselage area behind the maingear mounting with just 4 clean cuts using a sharp cutter. I found plenty of space there for the cables and also ferrite rings. From there i just pushed one more hole into the foam to reach the servo mount area.
To finalize the work you just glue the cut foam part back in place.
Here are some pics of my work:
5 Photos
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The cone shaped washer/ spacer should go between the ball and horn if you use it. Allows the ball link to be used at greater angles.
Originally posted by Skosh25 View PostAfter about a dozen flights with no issues I decided anyway to do my elevator upgrades today. Overall very pleased with how it turned out. Used the F-14 wing swing pushrods with 4-40 safety lock kwik links. Test flights tomorrow. (and yes, I have RF chokes, cap packs, crow in ailerons/flaps, and elevator Y to receiver).
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For those of you who want to install the elevator and rudder servo cables the same way i did - find attached some pics of the angle of the holes you need to drill or push in the foam and maximum distance you can push in order to not damage other areas. For the hole at the maingear don‘t push deeper than 6,5cm. For the hole in the tailsection don’t push deeper then 7,5cm.
Here the angle you need:
6 Photos
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