Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[Evan D]

I keep hearing “high current” ESC and now BEC. Not sure what is meant by that.

A brown out is when a receivers voltage goes below the minimum it needs to operate. Normally when this happens all servos stop working and the signal to the ESCs stop and most ESCs stop giving the motors power so they windmill to a stop, usually quickly on a EDF. Most receivers have a short period it takes to reestablish the receiver/ transmitter connection. Older Spektrum was up to about 3 seconds. Newer radios are a second or less.

Receivers are susceptible to ESC switching feedback. This is what the ferrite rings on the signal wires to the receiver are for and what I believe people using chokes are trying to defeat. 72Mhz receivers have more issues with this than 2.5Ghz.

[Dan B]

Hey Guys,
Lots of good feedback on my crash, just wanted to post another pic that shows the pre-crash location of my electronics and RX (AR620). I never had an electronic glitch before in all my years of flying, but looking at this setup now there is a LOT of spaghetti there with potential to be crash worthy. With the RX behind the battery it would be shadowed when the plane was flying towards me. Come to think of it, every MiG crash video I've seen is when the plane is flying towards the pilot. Hmm...

I had battery left after the crash (3.83v), but; Loss of RF signal due to proximity of battery? Electronic interference that could be resolved by additional RF chokes? Brownout? RX with additional satellites? Bypass blue box? Lots to ponder on my next build!

[Evan D]

I can tell you I always use receivers with redundant receivers in them and then use two single satellites or redundant satellites in larger aircraft with careful placement of antennae. In my big MiG I have a receiver with two internal receivers and have it under the back battery tray. Each long coax antennae goes out from there to the sides so the exposed portion of the antennae are far away from the battery and on either side. The satellite is also a dual receiver type with long coax antennae and is in the nose with one going further forward and the other up the top of the nose at a right angle. My MCBe has been moved to the side of the rear battery and I only have the retracts, gear doors and lights going through it.

I have ailerons, flaps, rudders, elevators, steering, the BEC and throttles All going direct to the receiver. The throttles are Y’ed into the receiver with a 6mm Y. I have the BEC and a 10mm extension I use for rebinding also Y’ed into the receiver with a high power Y. All others got appropriate extensions, for example I removed the extensions on the elevators and rudders and put in shorter ones just long enough.

Doing all this left me with a setup I have confidence in. None of this is to say someone else’s setup won’t work too.

[mshagg]

Asking to learn....Is a brown out REALLY that common with these high current UBECs? Man....they can pump out a lot of current!!
Or....is a brown out just a convenient go-to based upon history when the UBECs were only able to supply lower current levels.

No trying to be a smart a - - but would like to know.

-GG

It's hard to know given people dont really get definitive answers on the cause for a crash. When a plane stops responding it's easy enough to chalk it up to a brownout and move on. If enough people do that then, by the magic of the internet, all of a sudden freewing's stock 8A gets a reputation as a "known problem", just like the blue box. Heck even I've fallen into that trap and fitted castle BECs to the last two planes that I built lol.

[Scale Master]

Hey Guys,
Lots of good feedback on my crash, just wanted to post another pic that shows the pre-crash location of my electronics and RX. I never had an electronic glitch before in all my years of flying, but looking at this setup now there is a LOT of spaghetti there with potential to be crash worthy. With the RX behind the battery it would be shadowed when the plane was flying towards me. Come to think of it, every MiG crash video I've seen is when the plane is flying towards the pilot. Hmm...

I had battery left after the crash (3.83v), but; Loss of RF signal due to proximity of battery? Electronic interference that could be resolved by additional RF chokes? Brownout? RX with additional satellites? Bypass blue box? Lots to ponder on my next build!

What kind of receiver was that? It doesn't look like it's a redundant RX which was more than likely the cause of your burn in...

[themudduck]

I can tell you I always use receivers with redundant receivers in them and then use two single satellites or redundant satellites in larger aircraft with careful placement of antennae.....

Of course all of us can only make educated guesses at the reasons for Dan B's unfortunate crash. I agree with EvanD's comments... its really important to mount the receivers away from things that can block the signal. Such as batteries, piles of wires and carbon fiber. On my Mig I located the radio gear this way: blue box and Gyro on the center hump between the two batteries, 10ch Admiral receiver on the floor of the empty front battery tray, and the satellite was put all the way into the nose. The two receiver's antennas are 90 degrees to each other on different planes as well. (main receiver on the floor, satellite receiver on the side) I did use a Y-cable to bybass the blue box for the elevators.

Locating the receivers as far as possible away from sources of interference is pretty much the standard procedure. But its awful not knowing what caused a problem. I'm sorry Dan!

[Evan D]

AR 620 Spektrum. Actually a pretty decent receiver.

https://www.horizonhobby.com/product/ar620-dsmx-6-channel-sport-receiver/SPMAR620.html?KPID=SPMAR620&CAWELAID=320011980001444161&CAGPSPN=pla&CAAGID=97846720982&CATCI=pla-899697921242&utm_campaign=shopping&utm_medium=cpc&utm_source=google&gclid=CjwKCAjw_NX7BRA1EiwA2dpg0v3pJ8Xu1NHMjgNJCm6JexRUgbUpCO6VizDT0vw0ZtHIFZZGa68-EhoCU0oQAvD_BwE

[crxmanpat]

Here's where I mounted my RX in the forward area. The antennae go forward from it and mounted 90° from each other.

[xviper]

My chokes are going on tonight and maybe a set of Rosary beads for good measure

xviper, do you guys fly out in Airdrie? I'm in Calgary all the time for business and would like to come out to the field.

Yes, that's one of my clubs. It's actually on the Balzac gas plant property. The entrance is the one just before you get to the entrance to the gas plant guard house. It's on the east edge of that big pond (the one with plane bits floating in it ). The club is AMAS. I also fly at Foothills Flyers just east of Strathmore.

[Airguardian]

Asking to learn....Is a brown out REALLY that common with these high current UBECs? Man....they can pump out a lot of current!!
Or....is a brown out just a convenient go-to based upon history when the UBECs were only able to supply lower current levels.

No trying to be a smart a - - but would like to know.

That's actually being smart!
(As in, a positive thing!)

What I've learnt in my years of experience flying is that receivers will drop the link when voltage drops below operating threshold, and this can happen pretty easily when the power distribution is not ideal. There can be a number of 'weak-links'. In early days, the issue usually was that the BEC was integrated with the ESC and as this overheated, the BEC failed, or if the ESC fried... go figure! (:

Now we're more often seeing use of separate UBECs which reduce risk of getting killed along the ESC but most stock setups are still intended to run off a single battery pack... the same that feeds the motors. And we strain those packs A LOT in EDF applications so there is plenty that can go wrong there too, batteries being weak, over-drained, under too heavy a load by the EDFs, the packs can also die because of over-strain, getting too hot, etc... If you lose power you can still glide, but if you lose receiver/servos you are toast.

In that regard, I find using separate UBECs AND rx Li-Po packs (usually 2S) works best, but some will still tell you that puts you at risk of forgetting to replace rx battery and end up having an accident all the same... one that could have been avoided, and they'd be right. I'm just very thorough in terms of battery discipline and I even oversize batts a bit to allow for mistakes (My rx packs will easily do 3 to 4 flights but I replace them each two flights regardless).

Ultimately, it seems that on EDF Jets with over 10 servos, LEDs, retracts and all, currents can go wild some times, and the amp ratings of the UBECs may not cope, particularly if running from main battery packs that have been over-stressed by the EDFs, more so if they are of poor quality.

I had AT LEAST two crashes back in the day that were a direct result of this. Running ESC integrated BECs on the Eurofighter, I'd toggle the retracts to deploy at the end of the flight and the plane would immediately plunge to the ground. This happened to me TWICE until I found out what the issue actually was (Misidentified it the first time, leading to a second crash).

I then started using separate Rx Li-Po packs with their separate UBEC, and haven't (presumably) ever had an issue since. For the last 6 years or so I had only a couple of lost-signal scares that didn't result in a crash (and one that did) that I would attribute to other issues.

[mshagg]

In that regard, I find using separate UBECs AND rx Li-Po packs (usually 2S) works best, but some will still tell you that puts you at risk of forgetting to replace rx battery and end up having an accident all the same... one that could have been avoided, and they'd be right. I'm just very thorough in terms of battery discipline and I even oversize batts a bit to allow for mistakes (My rx packs will easily do 3 to 4 flights but I replace them each two flights regardless).

I have one bird set up like this because 8S capable ubecs dont grow on trees and HV ESCs are typically opto. It's actually really nice being able to power the plane up without plugging in the main flight pack. For that reason alone its something I'll probably implement on other planes over time.

[Hugh Wiedman]

Hey Guys,
Lots of good feedback on my crash, just wanted to post another pic that shows the pre-crash location of my electronics and RX. I never had an electronic glitch before in all my years of flying, but looking at this setup now there is a LOT of spaghetti there with potential to be crash worthy. With the RX behind the battery it would be shadowed when the plane was flying towards me. Come to think of it, every MiG crash video I've seen is when the plane is flying towards the pilot. Hmm...

I had battery left after the crash (3.83v), but; Loss of RF signal due to proximity of battery? Electronic interference that could be resolved by additional RF chokes? Brownout? RX with additional satellites? Bypass blue box? Lots to ponder on my next build!

Dan B that looks like maybe a Spektrum AR 637T. You got a lot going on there over the top of the receiver and I assume where the twin antennae come out on the port side that must be running fore and aft, right along side of each of the batteries. IMO, that's a potential problem right there. I have only had 1 brown out in my somewhat "short" (compared to a lot of you guys) RC life, and that was when I mindlessly ran the main antennae of an AR636 right along side of the battery, and then it only reared it's ugly head after some 60 flights. Since then I've been on a mission to make sure my main antennae are as far from wires and batteries as possible and in all my EDF's, I have installed at least 1 remote satellite receiver 18"-24" away from not only the main receiver but any batteries or wires, usually way up in the nose. Ferrite chokes have also been added as per GliderGuy recommendation, just in case. I know you feel that you still had throttle during the crash, but if you were at a 45 degree down angel, the Mig had a lot of gravity moving it along and it may have just seemed like that.

[Reaper911]

Hey Guys,
Lots of good feedback on my crash, just wanted to post another pic that shows the pre-crash location of my electronics and RX (AR620). I never had an electronic glitch before in all my years of flying, but looking at this setup now there is a LOT of spaghetti there with potential to be crash worthy. With the RX behind the battery it would be shadowed when the plane was flying towards me. Come to think of it, every MiG crash video I've seen is when the plane is flying towards the pilot. Hmm...

I had battery left after the crash (3.83v), but; Loss of RF signal due to proximity of battery? Electronic interference that could be resolved by additional RF chokes? Brownout? RX with additional satellites? Bypass blue box? Lots to ponder on my next build!

Irrelevant, but what do those batteries weigh in at ?

[Airguardian]

Probably very obvious but add the EDFs, motors and ESCs to the list of things you want to keep your receivers and antennas away from.
Also mind some paints (Mostly those with metallic particles) can shield or block radio waves. I am confident this is taken account of on our Freewing birds so we can mostly consider foam transparent to radiation but it is good having in mind for other builds.

Carbon fiber blocks RF, glass fiber does not! ;)

It's actually really nice being able to power the plane up without plugging in the main flight pack.

Oh, yeah, there's that too... I'm so used to that feature now on all my jets that I almost forgot it's not the usual thing, hahaha!
Definitely one of the bigger pluses, let's you work on the jet without being anxious about accidentally hitting the throttle on Tx. :)

[Evan D]

A brown out is when the voltage goes so low the receiver doesn’t work. This is different to a loss of signal where the receiver is working but the link between transmitter and receiver is broken for what ever reason.

Dan B that looks like maybe a Spektrum AR 637T. You got a lot going on there over the top of the receiver and I assume where the twin antennae come out on the port side that must be running fore and aft, right along side of each of the batteries. IMO, that's a potential problem right there. I have only had 1 brown out in my somewhat "short" (compared to a lot of you guys) RC life, and that was when I mindlessly ran the main antennae of an AR636 right along side of the battery, and then it only reared it's ugly head after some 60 flights. Since then I've been on a mission to make sure my main antennae are as far from wires and batteries as possible and in all my EDF's, I have installed at least 1 remote satellite receiver 18"-24" away from not only the main receiver but any batteries or wires, usually way up in the nose. Ferrite chokes have also been added as per GliderGuy recommendation, just in case. I know you feel that you still had throttle during the crash, but if you were at a 45 degree down angel, the Mig had a lot of gravity moving it along and it may have just seemed like that.

[Dan B]

Irrelevant, but what do those batteries weigh in at ?[/QUOTE]

FYI. I also fly these in my Avanti and F-22, no issues. Around $75 bucks.

Turnigy Heavy Duty 5000mAh 6S 60C Lipo Pack w/XT-90
Specs:
Capacity: 5000mAh
Configuration: 6S1P / 22.2v / 6 Cell
Discharge: 60C / 120C (Burst)
Weight: 838g
Dimension: 146 x 51 x 57mm
Charge Plug: JST-XH
Discharge plug: XT-90
Wire Gauge: 10AWG

[xviper]

FYI. I also fly these in my Avanti and F-22, no issues. Around $75 bucks.

Turnigy Heavy Duty 5000mAh 6S 60C Lipo Pack w/XT-90
Specs:
Capacity: 5000mAh
Configuration: 6S1P / 22.2v / 6 Cell
Discharge: 60C / 120C (Burst)
Weight: 838g
Dimension: 146 x 51 x 57mm
Charge Plug: JST-XH
Discharge plug: XT-90
Wire Gauge: 10AWG

I use these batteries and they are very good, right up there with my Gens Ace, ChinaHobbyLine, Revolectrix. However, they are quite heavy for this Mig, so I use the Gens Ace 5000s, which weight nearly 100g less per battery.

[ColtPilot]

I'll stick with the Pulse 5000 45c as I've never had an issue with those or the RT 6250 35c. I'm good to go.

[Raydar]

I said I would update about the Aliexpress fuel tank well it arrived and is the same tank as the Banggood one so is a alternative option of purchase if Banggood do not restock.

[Lcacing]

I was thinking I getting the rocket pods printed and when I showed it to a flying buddy, he said he already had a set and I could have When I got them they were smaller than the ones made by
Dirty Dee, after I installed them, even though not to scale, I liked the look better, more stream line. He also gave me other armament that he uses on his A-10.