Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[kallend]

Sure,

I've got a Spektrum IX20 and picked One Aileron One Flap as wing type and Dual Elevator One Rudder as the tail type.
I'm running a Spektrum AR8360T receiver with a Spektrum 4651T remote satellite receiver in the nose (connected with a SPM9104 36" receiver extension cable) and an RCLightsystems serial channel expander to increase my channel count to 11 which I'm using as follows:

For those who like tinkering and have Arduino knowledge, I have a channel expander design that will add 6 channels to an AR630, AR631, AR637T (or an AR8360T) and I am willing to share my version of the code (a modified version of the code posted on Github by kambalunga from RCG). It uses an Arduino Pro Mini + one Schottky diode, so the cost is minimal, around US$6

For those willing to wait, the FCC has details of a new Spektrum 10 channel stabilized receiver, https://fccid.io/BRWSPMAR10360T/User...Manual-4950535

[janmb]

Has there been any problems with elevator servos with the new up upgraded servos that MRC now put in the Mig 29. Do not want to risk this £600 model. I brought a second hand Mig 29, it has the MRC upgraded servos installed just want to know if they are up to the job and the problem has been sorted

Haven't seen much crash reports lately at all, and none with upgraded FW servos as far as I know.

That said, there is plenty arguments to be made for upgrading further though. Considering the weight class of the model, poorly balanced FFS tailerons, etc, the norm would typically be 10 kg/cm or more. In other words far beyond what the FW upgrades offer too. Even if probably not strictly necessary, better servos typically means more margin, better precision and better response times.

[RudyD54]

For those who like tinkering and have Arduino knowledge, I have a channel expander design that will add 6 channels to an AR630, AR631, AR637T (or an AR8360T) and I am willing to share my version of the code (a modified version of the code posted on Github by kambalunga from RCG). It uses an Arduino Pro Mini + one Schottky diode, so the cost is minimal, around US$6

For those willing to wait, the FCC has details of a new Spektrum 10 channel stabilized receiver, https://fccid.io/BRWSPMAR10360T/User...Manual-4950535

I’m one who loves tinkering and experimenting so I would definitely be interested in this.

[Evan D]

I agree fully to move from Phillips to hex and have made the change on many models.

[kallend]

I’m one who loves tinkering and experimenting so I would definitely be interested in this.

PM sent.

[themudduck]

Gentlemen, if I can go back for a minute to the well-worn subject of elevator servos that sometimes stop working....I noticed something interesting in the manual of the A3-L Gyro when installing it on another plane.
I use this gyro on my Phantom and a few other planes and really like how it locks the plane in.
I also have it on the MiG and it has been working well.

Anyway, you know how the A3-L has that little capacitor that you plug into any unused channel?
Look what the manual says (I added the bold):

"VOLTAGE PROTECTOR
After installing the gyro, the servos will move more frequently than before. It is highly recommended that a reliable UBEC or ESC be used to provide sufficient working current for the servos on the plane, otherwise the gyro may become unstable by an occasional voltage drop. A large capacitor can be used to get a more stable and secure voltage level. You just need to simply plug it into any open slot of the gyro or receiver."

So didn't we discuss that one possible reason for the elevator failure is voltage drop (digital servos stop working if the voltage goes below a certain level)?
And someone earlier in the thread tested that it is possible for the voltage to drop in certain conditions?

I am using the A3-L with the capacitor. A "voltage protector" seems like an excellent idea! Do any of you guys know, would there be any harm to adding another capacitor since that might provide some extra insurance against a voltage drop in the system?
Just wondering if you have any opinions about this. thanks!

[radfordc]

I am using the A3-L with the capacitor. A "voltage protector" seems like an excellent idea! Do any of you guys know, would there be any harm to adding another capacitor since that might provide some extra insurance against a voltage drop in the system?
Just wondering if you have any opinions about this. thanks!

My "go to" method of protecting against voltage drops or BEC failures is to include a 4.8v NiCd battery in parallel with the BEC. My routine is to plug in the main battery and check that the BEC is operating. Then I plug in the 4.8v pack into any open slot in the receiver. If all receiver slots are filled just use a Y cable on any one. Since the BEC is outputting 5v the battery doesn't provide any current to the system and in fact is being slowly (very slowly) charged by the BEC. If for any reason the BEC drops below 4.8v the battery will begin to provide power to the electrical system. I use small battery packs (400-600 mah) that weigh relatively little but will supply enough power to complete a flight. Since the battery doesn't provide any power to the plane under normal conditions it will not discharge over a season of flying.

[xviper]

I don't like having a second live power circuit hooked up to the BEC circuit but that's just me. I used to use one of these, but they have been discontinued for online purchase:

https://www.amainhobbies.com/scorpion-backup-guard-scp-sc-bug/p239994

After hundreds upon hundreds of flights in a multitude of different planes without any BEC incident, I stopped worrying about it and stopped using the Scorpion.
There is a new replacement product that's even smarter and if I ever start to have doubt in any stock BEC, I'll get this:

https://www.amainhobbies.com/optipower-ultraguard-back-up-solution-combo-opt-oprus2s/p676084?gclid=EAIaIQobChMIy5bMkKO11wIVDpl-Ch1_UwhTEAMYAiAAEgL6_fD_BwE

These things don't add or take away anything from the stock BEC system so long as it works normally. It's only when it senses BEC malfunction, that it will activate and intervene in milliseconds to power the RX.

[fredmdbud]

Gentlemen, if I can go back for a minute to the well-worn subject of elevator servos that sometimes stop working....I noticed something interesting in the manual of the A3-L Gyro when installing it on another plane.
I use this gyro on my Phantom and a few other planes and really like how it locks the plane in.
I also have it on the MiG and it has been working well.

Anyway, you know how the A3-L has that little capacitor that you plug into any unused channel?
Look what the manual says (I added the bold):

"VOLTAGE PROTECTOR
After installing the gyro, the servos will move more frequently than before. It is highly recommended that a reliable UBEC or ESC be used to provide sufficient working current for the servos on the plane, otherwise the gyro may become unstable by an occasional voltage drop. A large capacitor can be used to get a more stable and secure voltage level. You just need to simply plug it into any open slot of the gyro or receiver."

So didn't we discuss that one possible reason for the elevator failure is voltage drop (digital servos stop working if the voltage goes below a certain level)?
And someone earlier in the thread tested that it is possible for the voltage to drop in certain conditions?

I am using the A3-L with the capacitor. A "voltage protector" seems like an excellent idea! Do any of you guys know, would there be any harm to adding another capacitor since that might provide some extra insurance against a voltage drop in the system?
Just wondering if you have any opinions about this. thanks!

That might plausible if the battery is close to the end of the flight, but not with a good percentage of capacity is left (unless your battery has a high series resistance, old and/or puffed). Cable resistance is also a contributor to voltage sag at the servo.

In one crash case, a 2nd BEC was used to power the elevator servos, so voltage drop was not a problem (stepping 22.8V down to 5V leaves quite a bit of headroom).

If you are using a Spektrum receiver, they generally don't recommend it. But if it will give you peace of mind, use it.

[Captain Moron]

I am going to take a lot of flak here but it needs to be addressed. Does the Freewing Mig 29 have a serious design fault!!!!!. I am talking about this elevator problem? Please do not say that if you install 2 HiTec B85 servos and reinforce the elevator push rods it will be OK. Come on I do not expect to pay £600 for a model and have to do all that. Love this model but put off paying £600 for a model if it has a mayor problem with it!!!!!!!

[Evan D]

Capt. In my opinion yes it could be better designed. I will say the F-18 and maybe some other full flying stab airplanes, not just FreeWings also fall into that category.


As far as extra batteries, BECs or what ever, if you don't trust your system do some voltage tests and do what you feel necessary. But I have seen many people cause other issues, extra connections, sometimes many, other failure points, ground loops. Sometimes we are our own enemy. KISS

[radfordc]

I don't like having a second live power circuit hooked up to the BEC circuit but that's just me.

After hundreds upon hundreds of flights in a multitude of different planes without any BEC incident, I stopped worrying about it and stopped using the Scorpion.

I agree that BECs are reliable. Capacitors are often added to the power system to guard against transient voltage dips and spikes. A small battery is just another type of capacitor...just one with a huge capacity compared to the electronic capacitors. It is akin to adding hundreds of capacitors to the system. As long as the battery voltage is equal to or less than the BEC it has no effect on the BEC.

[radfordc]

I am going to take a lot of flak here but it needs to be addressed. Does the Freewing Mig 29 have a serious design fault!!!!!. I am talking about this elevator problem?

Love this model but put off paying £600 for a model if it has a mayor problem with it!!!!!!!

I think if you buy this model you will just fret and worry yourself needlessly and not get any enjoyment. Don't do it. The fact that many, many are flying successfully is not relevant.

[JamesonC]

I am going to take a lot of flak here but it needs to be addressed. Does the Freewing Mig 29 have a serious design fault!!!!!. I am talking about this elevator problem? Please do not say that if you install 2 HiTec B85 servos and reinforce the elevator push rods it will be OK. Come on I do not expect to pay £600 for a model and have to do all that. Love this model but put off paying £600 for a model if it has a mayor problem with it!!!!!!!

I really can't speak to any design flaws since I have never had one. However, if they were in stock right now, I'd own one.

[Captain Moron]

Also radfordc there are a lot of people paid a lot if money for this model only to see it crash through no thought of there own. You are right I have been offered a second hand Mig 29 because the owner is no longer confident to fly he's Mig 29 any more for fear of this problem. I have now declined he's offer to buy it for the same reason because I do not think adding different servo will fix this problem. So you think that is OK to sell an expensive model with a know problem?

[Captain Moron]

Capt. In my opinion yes it could be better designed. I will say the F-18 and maybe some other full flying stab airplanes, not just FreeWings also fall into that category.


As far as extra batteries, BECs or what ever, if you don't trust your system do some voltage tests and do what you feel necessary. But I have seen many people cause other issues, extra connections, sometimes many, other failure points, ground loops. Sometimes we are our own enemy. KISS

Thanks Evan D I think you completly right in what you have told me. It makes sense to what is happening with this model. I think I wait and see what happens to the Mig 29 when it comes back in stock and see if any thing has changed with this model but at the moment I think I will leave it at that

[Griffon Wings]

Thanks Evan D I think you completly right in what you have told me. It makes sense to what is happening with this model. I think I wait and see what happens to the Mig 29 when it comes back in stock and see if any thing has changed with this model but at the moment I think I will leave it at that

Hi Cap. M. , i can’t denied to crush mine for unknown reason, specially after working hours and hours and much extra money between upgraded pilot, paint,whistles, decals ,afterburners reciver and batteries...BUT, would i give another chance to this plane ??? HELL YES i will and besides we don’t know yet if improvements was done or not ( i WANT belive so ).
Only complaint, but useless, the price increase in general. I get it, was determined from shipping companys, but, 10-15% on a plane, same on batteries, same for recivers ( in general) ect ect ect add quickly another 100$ On top of it.
Solution for me ? Buy less planes add some tanks, boats, cars and on , keep cost “ down “ and the spirit high for the rc .

[Gringotuerto]

Do any of you guys know, would there be any harm to adding another capacitor

Nobody actually answered the main question unless I missed it. Short answer is no, there should not be any harm in adding another cap.

When you first power on, the initial current will be the max the BEC can supply (call it Imax), and the voltage will rise as Imax/C = dv/dt. So if C is twice as big, dv/dt will be half as big, and it will take twice as long to charge up the cap. In theory with an infinitely large cap you could get into a situation where this stresses the BEC being effectively "shorted" to 0v for a long time, but in practice with the sizes of caps we're talking about, this is not a problem. To verify this, you can do the following quick check - the one that comes with Eagle is 3300uF. So if your BEC is putting out 5A, then that cap will charge at a rate of 5A/3300uF = about 1500 volts/second. In other words, it will charge up to 5v in about 3milliseconds. That is not going to stress the BEC putting out max current for 3ms. And if you put 3 of those caps on your Rx it would just triple the time, so around 10ms. In fact the BEC doesn't wake up and start supplying 5A immediately, it has it's own output capacitance and so on. But the point is, the time required to charge caps at the Rx are very short. So with practical sizes of caps, power up is not going to be an issue.

[kallend]

Thanks Evan D I think you completly right in what you have told me. It makes sense to what is happening with this model. I think I wait and see what happens to the Mig 29 when it comes back in stock and see if any thing has changed with this model but at the moment I think I will leave it at that

It's been "Out of stock" for quite a while.

It would not surprise me in the least if there are changes when it finally comes back in stock.

[Captain Moron]

You have to ask why has it been "Out Of Stock " for so long!!!!!!!
Think it is best if we leave it there. We all have choices you either want to buy the Mig and take a chance or decline from buying one untill it is sorted