Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[Airguardian]

Oh by the way, does the new MIG have a blue box.??

The same as on the Hornet if I am not mistaken!

[themudduck]

A follow up on an earlier post for two stage doors. Here are the pins to move from the wing wiring harness connectors at the blue box. Remove the 3rd wire (next to the red wire) and solder those together and install a connector to connect directly to the blue box two stage door output. Works great and as others pointed out, is not scale but looks cleaner and is cool!! I don't remember who posted the first note about the blue box having two stage door output but credit to them.

Thanks a lot for your post with the pic, it helped clarify and I performed this modification - worked perfectly. Excellent!

[crxmanpat]

Some rambling thoughts (was out flying all day today and too many posts to quote, so bear with me).

On the flap servo issue, seems to me that the flap servo in question may be bad. I don't think it had anything to do with the blue box. What I think happened is the servo overheated and stopped working and went to full up setting on approach. Then later when it cooled off, it started working again. Hopefully Motion can look at it and determine whether or not it is bad and should be covered under warranty.

Here's my take on the whole "bad elevator servo" issue. I personally don't think the servos are bad, I think there is a combination of factors contributing to crashes, which are:
1. The geometry of the pushrod is not ideal. If you look at the F-22, the servo arm to control horn is at almost a perfect 90° angle. On the Mig, the pushrod is off that angle by about 10°. Having the control rod in the middle hole increases that angle. The reason I bring up the F-22 is that it has the same 17g MG servos on the elevators as the Mig. I fly my F-22 on 12S, and the servos handle the load just fine. But the F-22 has that ideal pushrod geometry.
2. People did not read the manual and put the control rod in the outer hole as indicated.
3. I think the initial crashes were also nose heavy. The manual states to install the forward battery tray and I think guys were just automatically assuming that you install the forward battery there. I don't know this for sure, but seems likely based on the videos I've seen.

I flew my first two flights with the original servos. It flew just fine as I had it set up properly. I now have the new servos in and flew it one flight this morning.

Brent Hecht showed up at the event today with his Mig. He did a couple things that I will now be doing as his seems faster than mine. First he opened up the cheater holes some. Seemed to him like the fans were getting slightly stalled. Opening up the cheater seemed to solve this. He also made the exhaust smaller by a couple mm. Need to find out tomorrow by how much.

[mshagg]

I knocked up some beefier servo rods based on 4-40 allthread as the stock ones still had some flex in them in the parts not captured by the carbon tube. Whether that has an impact on flight performance I am not qualified to say, but the weather has been miserable so what else are ya gonna do lol (have since installed the dubro heavy duty servo horns so its all very solid now). May go back and fit some carbon tube just for aesthetics as I really like the appearance of the factory setup.

The dubro heavy duty ball link (Part #899) comes with a spacer, I am guessing for surface vehicle tie rods which need to accomodate the ball link swivelling throughout suspension travel. But it straightened up the geometry of the pushrod somewhat.

[Teslamandex]

This is my first twin ESC equipped plane with two batteries. I have successfully calibrated twin ESC's on eFlight Twin Otter, FMS F7F Tigercat, and eFlight A-10 Thunderbolt 2. Going through process of:

1. powering up my Spektrum Dx8 G2 transmitter with throttle stick set to maximum up position.
2. connecting ESC to the battery (or ESCs to respective batteries with regard to MiG-29), listening for the series of double beeps.
3. then quickly bringing throttle stick down to minimum position

This process has not produced the same outcome on my Freewing MiG-29. When I move the main throttle toggle from its minimum position to a point where the fans start, both fans come on fairly close together. However, if I leave the toggle at its lowest position and try to start the fans with the trim tab, the port fan always starts 2-3 clicks earlier than the starboard fan. Very frustrated. Just as a note, I connect the ESC with the UBEC last. Not sure if it matters.

What am I doing wrong? Am I worried about something that is insignificant in the first place?

[GliderGuy]

Good show mshagg - My setup exactly! Strong!

Teslamandex - ALWAYS Connect the UBEC+ESC first....always! That gets your system powered up for all aspects.

No rush as you are performing the programming actions...The ESCs ain’t going anywhere.

Here is what I did.....AFTER completing the transmitter+receiver binding process

Chock the wheels REALLY WELL...in case you mess up and she comes alive at full power! A HARD learned lesson.
I had a prop plane jump off a workbench straight into my hand....trip to emergency room.

1. Transmitter on and set to full throttle
2. Connect ESC+UBEC / You will soon hear the twin beeps...just let her sit...no action needed
3. Connect the other ESC / You will soon hear the twin beeps
4. NOW set the throttle to minimum / You will soon hear the single beep after the cell count beeps (May or may not be able to distinguish the single beep from each ESC)
5. You are finished.

-GG

[mshagg]

Good show mshagg - My setup exactly! Strong!

Thanks for the idea! Upgrade program underway for all of the big jets now.

[Gringotuerto]

... I connect the ESC with the UBEC last. Not sure if it matters...

I agree with GliderGuy that connecting the one with UBEC first is better. It powers your Rx and you Rx starts putting out 2ms pulses, which you want to appear at the ESC as soon as it becomes conscious. Also, note that most ESCs will enter a programming mode (and let you know by beeping again) if they see high throttle for a long time, like 5 seconds. So you don't need to make great effort to hurry, but you do need to connect the two one right after the other.

As far as minor mismatch, I personally wouldn't worry about it. I have done design for ADC's and DAC's in that range (i.e. around 12 bits), and it is pretty hard to get two to match precisely. Our application was probably more cost-tolerant than this one, and included a multi-point linearization table, and a thermistor and temperature correction table. Still we would get around 5-10 codes of INL (integral non-linearity) between units. We don't have access to the detailed specs for the ESC, but if they can do better than a couple clicks of trim I would be surprised. I don't know how your Tx is set up, but mine defaults to 5/2048 per click. So 2-3 clicks is 5-15 codes of a 12-bit range. That's not fantastic INL, but not worse than I would expect for a cheap pulse-width counter.

But having said that....I'm about to do the ESC calibration step on mine, so I'll also try your trim experiment and let you know the result.

[janmb]

Successful maiden today! Flight was with the replacement servos installed. Only got 2 flights on her. Needed some up trim at factory CG but not too bad. Seemed really "twitchy" to me in the roll channel at factory throws so I reduced them to half of recommended for the second flight. That was much more to my style of flying. Second flight, I moved the front battery a 1/4" aft and took out some up trim but it looked tail heavy in the turns so I'm going to go back the original CG. Seems like a pretty honest flyer overall. Lands well and isn't a handful to fly. Definitely a keeper!

Congrats on the maiden, as well as the beautiful paint job!

The model dragging its butt a bit in turns is perfectly normal, and does not mean it is tail heavy (necessarily).

I strongly recommend getting used to actively use the rudder - it is a flight control that is just as important as ailerons or elevators.

[Teslamandex]

Good show mshagg - My setup exactly! Strong!

Teslamandex - ALWAYS Connect the UBEC+ESC first....always! That gets your system powered up for all aspects.

No rush as you are performing the programming actions...The ESCs ain’t going anywhere.

Here is what I did.....AFTER completing the transmitter+receiver binding process

Chock the wheels REALLY WELL...in case you mess up and she comes alive at full power! A HARD learned lesson.
I had a prop plane jump off a workbench straight into my hand....trip to emergency room.

1. Transmitter on and set to full throttle
2. Connect ESC+UBEC / You will soon hear the twin beeps...just let her sit...no action needed
3. Connect the other ESC / You will soon hear the twin beeps
4. NOW set the throttle to minimum / You will soon hear the single beep (May or may not be able to distinguish the single beep from each ESC)
5. You are finished.

-GG

Thanks Gringotuerto and GliderGuy. I will go this route when I get home from work. I’m not well versed on the nuances of radio electronics with regards ratio of trim clicks to channel resolution. Only know the Dx8 has 6 channels at 2048.

[janmb]

This is my first twin ESC equipped plane with two batteries. I have successfully calibrated twin ESC's on eFlight Twin Otter, FMS F7F Tigercat, and eFlight A-10 Thunderbolt 2. Going through process of:

1. powering up my Spektrum Dx8 G2 transmitter with throttle stick set to maximum up position.
2. connecting ESC to the battery (or ESCs to respective batteries with regard to MiG-29), listening for the series of double beeps.
3. then quickly bringing throttle stick down to minimum position

This process has not produced the same outcome on my Freewing MiG-29. When I move the main throttle toggle from its minimum position to a point where the fans start, both fans come on fairly close together. However, if I leave the toggle at its lowest position and try to start the fans with the trim tab, the port fan always starts 2-3 clicks earlier than the starboard fan. Very frustrated. Just as a note, I connect the ESC with the UBEC last. Not sure if it matters.

What am I doing wrong? Am I worried about something that is insignificant in the first place?

First of all, never mess with throttle trim on an electric setup. If your radio supports it, disable that trim entirely.

Second, I recommend calibrating one ESC at a time. It is hard to plug both in sufficiently simultaneously to enter programming mode on both

[Gringotuerto]

First of all, never mess with throttle trim on an electric setup. If your radio supports it, disable that trim entirely.

I think he was just using it as a small controlled input for an experiment, then putting it back to the centered position, and not proposing to use it for anything else. IMHO it is a reasonable and interesting experiment to do. But yes, you want to re-center it when you're done.

If you prefer the one-at-a-time method, then seems to me the easiest way on this model is to power the Rx with something other than the UBEC when doing the non-UBEC ESC (because the two throttle inputs are not easily separated). To me, that is slightly more effort than just plugging two things in within 5 seconds of each other. But either way can be done. Of course the one-at-a-time method has the advantage that you don't have two tones going on at the same time.

[janmb]

I think he was just using it as a small controlled input for an experiment, then putting it back to the centered position, and not proposing to use it for anything else. IMHO it is a reasonable and interesting experiment to do. But yes, you want to re-center it when you're done.

I assume so as well. Just wanted to be clear on the point since we've had pilots being confused about throttle trim vs ESC calibration issues before.

If you prefer the one-at-a-time method, then seems to me the easiest way on this model is to power the Rx with something other than the UBEC when doing the non-UBEC ESC (because the two throttle inputs are not easily separated).

Yep.

To me, that is slightly more effort than just plugging two things in within 5 seconds of each other. But either way can be done. Of course the one-at-a-time method has the advantage that you don't have two tones going on at the same time.

Yeah, both ways are certainly doable, just a pain to plug the second one in close enough to the first one and then make sure to calibrate both before the first ESC goes into the first menu option.

Some ESCs still perform calibration when pulling the throttle even if this also enters a sub menu, but some others don't. Don't know which category the ESCs in the MiG falls into. Just recall James trying to demonstrate this on the Bronco a while back, and did a perfect demonstration of too much gap leading to one ESC calibrating and the other not.

I generally tend to sort stuff like this while the model is still on the build table, using separate power source as required, and with only one throttle connected at a time.

[CristianMarin]

Replacement servos - ready
Wing connectors - ready (well, need some soldering)
Power receiver LiFe - ready
Plane - MotionRC?

[GliderGuy]

Hi Christian - You forgot these

https://www.amazon.com/Cedmon-Pieces...8870654&sr=8-4

and these! LOL

More bullet proofing - Reference prior posts.

-GG

[CristianMarin]

Oh, sure!

[Evan D]

Will you be powering your radio system directly with the LiFe packs?

[CristianMarin]

Evan D, yes. I will not use the blue box.

[xviper]

Yeah, both ways are certainly doable, just a pain to plug the second one in close enough to the first one and then make sure to calibrate both before the first ESC goes into the first menu option.

Some ESCs still perform calibration when pulling the throttle even if this also enters a sub menu, but some others don't. Don't know which category the ESCs in the MiG falls into. Just recall James trying to demonstrate this on the Bronco a while back, and did a perfect demonstration of too much gap leading to one ESC calibrating and the other not.

I generally tend to sort stuff like this while the model is still on the build table, using separate power source as required, and with only one throttle connected at a time.

Now that my Mig has arrived and is on the table, I can see what everyone is talking about.
The throttle lines on this plane are "Y'd" near the end that plugs into the RX. It's not that hard to do the throttle calibration by unplugging one line and doing the calibration one at a time. On the other hand, on twins where there are separate batteries for each ESC, I generally can hold both battery leads in one hand and plug both batteries in fast enough that there is very little lag time. If you can't plug them in fast enough, then one ESC will go into programming mode before the other one has finished the initial beeps. If you pull the stick down at that time, you've calibrated one ESC and set the BRAKE on the other, then we see posts like "Woe is me" from those who can't figure out why one ESC has the brake set.
As far as the throttle trim is concerned, most manuals say nothing in this regard, while some say to lower it to the bottom while yet others say to leave it in the middle where it starts out. Eflite does this on some models, as do many VTOL planes. So, unless it says otherwise, on any new model, I start by lowering the trim to the bottom. Rebind when the plane is finally set up, then go flying. How you do it is up to you.

Going back several pages where there was someone who had one of the nose gear doors catch on the strut and jambed up the retraction, I mentioned something about adjusting the "rod". Now, I'm not sure about whether or not this came into play but the owner indicated there are NO rods for the doors. Well, in fact, there ARE rods and the length of each rod determines how far each door goes open and whether or not the doors close flush. He went on to say that altering the strength and length of the spring fixed his situation.

[Bushong572]

I made 2 more flights today with a revised CG. I moved my RX and UBEC as far back as I could (beside the rear battery). My 2 RT 5500 mah are already as far back as I can get them. My new CG is 10mm behind the factory marks. The plane does fly better (you don't feel like you're having to hold the nose up all of the time). I now have 3mm of up trim instead of 5mm. I still think that is alot of trim, but I will probably leave it. I would have to add weight to the rear to move it back any further, which I might do eventually. The plane flies well and takes very little elevator to hold it inverted.

I'm curious about brake options. I run brakes on all of my EDFs and turbines (since I fly from a paved runway). The JPs in the stock wheel size are expensive and very heavy.