Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[Evan D]

In MY experience what you are describing is normally caused by feedback in the servo leads caused by resistance. Normally a bad connection at an extension connection or something similar. Remember the MCBe is basically a bunch of Y connectors. I think when you increase the supply voltage it’s pushing through this extra resistance causing the feed back.

What you need to do is track down the source of the resistance and correct or eliminate it. It may be dirty connections, bad solder joints in the MCBe, servo wires that are close to other wires (the chokes are a great fix if this is the cause but also twisting the servo wires can help if this is the issue ), or what ever.

The thing is that you still have an issue even though you are reducing the symptoms by increasing the voltage. If it was me I would bypass the MCBe with standard extensions and Y’s as a first step.

[GliderGuy]

Hi crxpatman,

Sorry for the confusion whereby I mixed in a different topic as an FYI. The RF chokes are not meant to address your chattering servo issue...which I gather was happening without the EDF fans running.

The info on the RF chokes was presented for your edification regarding RF noise generated by the ESCs when the fans are running. This "may' cause a complete loss of control as the noise may upset the pointer in the look-up table that the TX and RX are using when the binding/linking process takes place.

So to make things absolutely clear: (1) I don't have any inputs or suggestions for your chattering servo issue. (2) The RF choke info is to potentially prevent you from having a loss of control event due to the RF noise generated by ESCs during flight.

Hope that clears it up.

-GG

[Luqman Khan]

Thanks Evan - makes sense that its the individual components connecting to MCBe that have different tolerances for voltage.

Any idea about why my control surfaces attached to blue box (rudder, flaps, ailerons) would start automatic deflections (minor deflections but visible) when I switched from stock BEC to Castle BEC - here're my observations:

1. Stock BEC - no issues.
2. Switched to Castle 10amp BEC set at 5.1v: started getting servo chatter + surface deflections for anything connected to MCBe. Stock elevator servos were direct to receiver and no problems there. I also checked the telemetry data and receiver was outputting 5v to 4.9v (it kept oscillating between this range).
3. I changed Castle output to 5v and then 4.9v and 4.8v: with each drop the chatter and servo movements became more pronounced.
4. Finally I changed to 5.2v and everything went to normal and then for peace of mind I changed to 5.3v output at Castle BEC -- and no issues since then. I checked the telemetry and I get readings of 5.2 to 5.3v for receiver output.

The MCBe (blue box) isn't the issue with voltage, it's the items connected to the MCBe. The stock servos are okay up to 6 volts easy. The retracts are good to about 5.5. There is a sequencer in the MCBe and it's probably okay to over 5.5 but it doesn't matter because the retracts aren't. Last is the LED output slots. The LEDs themselves are 3-3.3V and there is a tiny resistor on each LED output that cuts the voltage the BEC supplies down a fraction. If you increase the input voltage the resistors reduction may not be down to the 3-3.3V the LED can handle and you may blow a LED. All that said 5.5 is the max you want to supply to the MCBe but it's because of the retracts.

[Evan D]

The MCBe (blue box) isn't the issue with voltage, it's the items connected to the MCBe. The stock servos are okay up to 6 volts easy. The retracts are good to about 5.5. There is a sequencer in the MCBe and it's probably okay to over 5.5 but it doesn't matter because the retracts aren't. Last is the LED output slots. The LEDs themselves are 3-3.3V and there is a tiny resistor on each LED output that cuts the voltage the BEC supplies down a fraction. If you increase the input voltage the resistors reduction may not be down to the 3-3.3V the LED can handle and you may blow a LED. All that said 5.5 is the max you want to supply to the MCBe but it's because of the retracts.

[Luqman Khan]

Thanks crxmanpat ... so I am well within limits at 5.3v (good to know).

GG,
In my case increasing the voltage increase (from 5.1 to 5.3v) fixed the servo chatter & automatic deflection of control surfaces that I was experiencing. I do have a choke on Bec cable but it seems my issue might not be related to interference else increasing output voltage from BEC (going to receiver and blue box) won't have fixed it (everything else being equal).

I found this article / additional information.

https://www.promodeler.com/caseSTUDY...reewing-Mig-29

FYI..I am using two MKS HV69 in my MiG-29 to drive the FFSs. The downside is that MKS doesn't offer a reverse version (or they didn't at the time I ordered). Rather than open one up and rewire it, I decided to install a servo reverser. The Futaba SR-10 was ordered. It has performed flawlessly for several thousand flights** and is very stable to ambient temperature changes. Some folks shy away from reversers, but the SR-10 has served me well.

For the hardware: heavy duty DUBRO connectors and a threaded 4-40 rod cut to length.

Also, you may wish to search the forum for RF chokes or ferrite chokes or just chokes. Read and learn. I use several of these on all my high-current ESC EDF birds. The MiG has 7 of them. Overkill? Maybe. But how many individual MiGs are flying that have several thousand flights logged w/o a single radio glitch? Here are the locations:

One small choke near each FFS servo (as close to the MKS HV69 as possible). There's a nice pocket ahead of each servo.
One larger choke on each ESC mounted as close to the ESC as possible on the battery side.
The green ferrite ring that comes stock.
I added another small one near the green ring.
The SR-10 came with its own.

Yep...that's a total of 7 chokes. Like I said...probably overkill, but the set-up is extremely flight proven.**

I'm gun shy after crashing an A-10 twice and an F-4 twice from loss of control events which a HAM Radio friend said was likely due to the noise generated by the high-current ESCs. Zero loss of control events since I started using the extra RF chokes on my high-current ESC EDFs.

-GG

**Estimated somewhat more than 2500 flights.

[GliderGuy]

Motion has said 5.5v max.

I found this article / additional information.

https://www.promodeler.com/caseSTUDY...reewing-Mig-29

FYI..I am using two MKS HV69 in my MiG-29 to drive the FFSs. The downside is that MKS doesn't offer a reverse version (or they didn't at the time I ordered). Rather than open one up and rewire it, I decided to install a servo reverser. The Futaba SR-10 was ordered. It has performed flawlessly for several thousand flights** and is very stable to ambient temperature changes. Some folks shy away from reversers, but the SR-10 has served me well.

For the hardware: heavy duty DUBRO connectors and a threaded 4-40 rod cut to length.

***SOAPBOX TIME***

Also, you may wish to search the forum for RF chokes or ferrite chokes or just chokes. Read and learn. I use several of these on all my high-current ESC EDF birds. The MiG has 7 of them. Overkill? Maybe. But how many individual MiGs are flying that have several thousand flights logged w/o a single radio glitch? Here are the locations:

One small choke near each FFS servo (as close to the MKS HV69 as possible). There's a nice pocket ahead of each servo.
One larger choke on each ESC mounted as close to the ESC as possible on the battery side.
The green ferrite ring that comes stock.
I added another small one near the green ring.
The SR-10 came with its own.

Yep...that's a total of 7 chokes. Like I said...probably overkill, but the set-up is extremely flight proven.**

I'm gun shy after crashing an A-10 twice and an F-4 twice from loss of control events which a HAM Radio friend said was likely due to the noise generated by the high-current ESCs. Zero loss of control events since I started using the extra RF chokes on my high-current ESC EDFs.

-GG

**Estimated somewhat more than 2500 flights.

[crxmanpat]

Motion has said 5.5v max.

[Luqman Khan]

Does anyone know what's the voltage range for bluebox that comes installed in mig29? I tried to look around but could not find any official figures.

Reason I ask (and apologies for long read):

My stock elevator servos (and the replacement sent by motion) were vibrating big times and after motion sent me a replacement for the originals I didn't even want to go back.... I replaced stock elevator servos with hitec 5245mg (drop-ins) and problem solved (replacements servos are as smooth as it gets).
While I was trying to figure out elevator vibrations (and before swapping out stock servos) i replaced stock BEC with basic Castle 10amp v1 BEC and set the output voltage to 5.1v but I noticed that caused chattering and (minor) deflections in control surfaces (ailerons, flaps, rudders)... but when I increased the output voltage to 5.3v all chatter/minor vibrations went away and I was even able to do an uneventful maiden today. I am using Spektrum AR637T receiver.

I'm afraid that I might fry the blue box at 5.3v - anyone knows the real voltage numbers bluebox can support? also, any idea why I would have gotten the servo movements on 5.1v but not with 5.3v?

[GliderGuy]

Nothing in this model offends me as much as the main gear. How it is solved by Freewing is profanation;). If they had done it from the fuselage and not from the wings, it would have looked better.

LOL - After several thousand flights on it, the FW MiG-29 remains the favorite of all my birds to fly...scale gear or not.

This is one well designed "wear tolerant" airframe....no fatigue cracks...nada/zip. Other than the occasional landing gear servo replacement, when one becomes intermittent, or a control servo replacement, when one begins to chatter...she's one tough bird.

As an update to prior posts, I've made a large number of landings after the replacement of the not-designed-to-be-replaced main gear plastic mounting box...some post-repair landings were not so good. It's holding up extremely well / better than I expected.

If you missed the details, below is a link to the prior post / how to do it.

#5186
Dec 12, 2021, 08:43 PM

Followed with more info in post 5187

-GG

[KevinMar]

I just wanted to share that I had a dream last night that I owned this Mig-29. That is all

[nuts-n-volts]

If grass is really that big of a problem, you can always just remove them. Then it can look unscale as this one does. ;)

[lusek_pl]

Nothing in this model offends me as much as the main gear. How it is solved by Freewing is profanation;). If they had done it from the fuselage and not from the wings, it would have looked better.

[crxmanpat]

Probably because grass fliers would rip them off easily.

[nuts-n-volts]

... and there ya go! Ingenious, my friend! I have always wondered why Freewing just didn't make this scale in the first place. It really would have taken no additional thought.

[lusek_pl]

lusek, how did you extend the doors? Material?

old pieces of a box and used credit cards;)

[nuts-n-volts]

lusek, how did you extend the doors? Material?

[lusek_pl]

I will refresh the topic a bit and show the progress in building the model.
Gear mod



Wing-fuselage fits all of them so?

hull beacon

beacon motor nozzle

I reprinted the engine nozzles because there was a problem with the matching. It looked bad

https://youtu.be/BDSkpAxRHLs

[nuts-n-volts]

Yep... unpopular. But it is your opinion. Maybe you should have DM'd if you really wanted to keep it on track?

[Airguardian]

This will be an unpopular opinion, but should these 'brave people' had not been 8 years crushing down on the freedoms of their countrymen in the East, they probably wouldn't have to fight for theirs now.

All war is horrible, but people seem to forget this one didn't start yesterday and that people being branded as heroes today have been murderers for a long time.
Not necessarily defending Russia on this, but Ukrainians have their hands filled with innocent blood too.

And we'd better not turn this thread into a political cesspool anyway, I'd suggest, feel free to DM your objections so the thread can stay on topic.

[Hugh Wiedman]

Outstanding report. I've seen several accounts on the internet and Youtube today with similar reports and accounts, but this video seems to include some specific data on the aircraft that the Ghost (what an superb handle ) apparently shot down that I did not see in any others. Thanks for sharing this!!! All of the reports I've seen also indicate that this may be a rumor at this point or if any of it is true the numbers may not be accurate. The first air combat ace in 25 years and the first in over 50 years to do it in one day!! WOW, I sincerely hope that it is completely accurate, but if only a portion is (or even just a well planted rumor), kudos to every one of those brave Ukrainian pilots and to the soldiers and even the citizens doing their best to defend their country and their freedom. Too bad our politicians have not had the b.... to help in any meaningful way. My next Mig-29 build will be definitely be the Ghost Mig!