Official FlightLine RC 1600mm P-38 Lightning Thread

[Aros]

Okay the ESC issue really needs to be clarified. Please, Alpha, when you get a chance, speak on this essential part of the build. Some people are saying because the ESC's are linear, you don't need to remove one of the red wires from the BEC lead and this is why it's not mentioned in the comprehensive build video. Yet others are saying it's a hit or miss thing (someone already fried their board) so you better remove the red wire...

Please Alpha, since you are the authority on this bird, give us the final word on this please.

[tdevince]

Aros, the problem will be more likely to occur if you do not parallel your two batteries together and thus may have slight differences in pack voltages. Then your two ESCs will not play well together. Regardless, there is no real benefit to not pulling one power supply wire IMHO.

[TiredIronGRB]

So it won't be an issue if you're using one battery?

[tdevince]

So it won't be an issue if you're using one battery?

I would say less of an issue, but I'd still pull one lead.

[OV10]

Okay the ESC issue really needs to be clarified. Please, Alpha, when you get a chance, speak on this essential part of the build. Some people are saying because the ESC's are linear, you don't need to remove one of the red wires from the BEC lead and this is why it's not mentioned in the comprehensive build video. Yet others are saying it's a hit or miss thing (someone already fried their board) so you better remove the red wire...

Please Alpha, since you are the authority on this bird, give us the final word on this please.

With Alpha being the 'authority" on this bird the real question he needs to answer so as to put to bed all the misinformation out there about the regulator type on the BEC from those saying that it is linear would be "is it linear or switching" . As I explained in my post #911 without the in depth electronic theory, the probability of FlightLine putting an older tech linear 4S BEC device on this bird is really unlikely because it would get really hot reducing the 14.8V down to 6V via voltage dropping. Don't know why there is such a resistance to removing one of the red supply wires to the Rx when using two BEC's.
Best regards,

[OV10]

Aros, the problem will be more likely to occur if you do not parallel your two batteries together and thus may have slight differences in pack voltages. Then your two ESCs will not play well together. Regardless, there is no real benefit to not pulling one power supply wire IMHO.

The subject isn't about parallel connection of the batteries, it is about the BEC lead.
They aren't pulling a MAIN power lead on one of the batteries, the red wire being pulled is on the 3 wire BEC lead.

[OV10]

So it won't be an issue if you're using one battery?

Not an issue because you don't have 2 BEC's to contend with.

[Alpha]

Without getting into a long electronics back and forth discussion, let me be definitive on this subject:

I have flown two prototypes and two production versions of the FlightLine 1600mm P-38L. 572 flights total over the past 12 months, which includes 43 other pilots' test drives (1-10 flights each). These flights were conducted with both a single 4s 5000-5800 mah, and with two 4s 2500-3000 batteries. The factory has several flying P-38s, having logged ~100 flights total over the same period. A handful of P-38s were delivered to Chinese customers in mid February. Bajora has the only other flying P-38 in North America, logging dozens of flights over the past 2 months.

ALL of these aircraft had both ESCs Y-harnessed together and plugged into the receiver's single throttle channel. ZERO red wires were removed from ANY of these aircraft.

Remove a red wire if you want, but do so knowing it's not necessary in the FlightLine 1600mm P-38L. The ESC manufacturer confirmed this over a year ago when we spec'd the ESC knowing it would be in a Twin environment, and 700+ flights backs it up. I didn't mention removing a red wire in the Build Video, because it isn't necessary.

For pilots wanting to substitute in a UBEC or a <6.0v receiver battery, refer to the installation manual for that component.

[xplaneguy]

Amen....now get'em in the air guys! ;)

[xviper]

Alpha, thanks for writing this in "stone". Dynam (and other brands) has been doing this the entire history of selling twin engined planes and I have built ARF twins using the same wiring scheme and never had any of my planes exhibit any kind of malady in terms of BEC problems. This topic seems to have and will always have a lot of polarizing thought. I figure if the manufacturer sells the product like that, then it's going to work fine out of the box that way. Too much superstition, "old wives tales" and "Chicken Little" watching going on. Sure, if you've had an "incident", then yank the second red wire all you like but then, was it really a problem with having 2 BECS at play? (Scratch head, look back and re-analyze.) I think we need to understand how electricity works and the concepts of "parallel and series". I'm retired now. I don't teach anymore.

[OV10]

Or you can do it my way and plug both ESC's into a heavy duty Futaba Y cable to "Let the smoke out" of the system. You'll be happy to know that the Aileron servo wire from the P38 control board is the weakest link in the system and it will completely fry (while you frantically unplug the batteries) before it damages any of the expensive equipment like the Futaba 7008 receiver and Eagle Tree Guardian Flight Stabilizer. I might also note that the foam is much more flame retardant that I thought. Obviously another example of forward thinking by the Flightline design team!

All kidding aside, Both ESC's seem to have survived the incident and both seem to be working as well as their respective BEC's. I'll probably tear her down tomorrow night and inspect every servo wire and check the function of every servo and light just to be sure. :) I have two other twin ARF's that I installed CASTLE ESC's in that are plugged together with no problem. In hind-sight I should have checked the voltages on these ESC's to make sure they were the same.

By the way, I HAVE DIBS ON ONE OF THE P38 CONTROL BOARDS BEFORE ALL YOU OTHER HOBBY HOARDERS START SNATCHING THEM UP FOR THE REST OF YOUR FLEET! I'VE GOT A P38 DOWN AND THE LUFTWAFFE IS INBOUND!

My last difference of perspective on this topic of BEC's in twin applications.
Am very curious as to the cause of the meltdown possibly being BEC related? If it is, then it becomes a 1 in 700(Alphas quote) failure statistic which is not very good and it may become even worse because of those 700 flights how many different aircraft were involved to get a sense of the number of ESC's actually tested.
With the above comment regarding CASTLE ESC's, every one of their device manuals whether it is the Talon or Phoenix indicates that the red wire on the BEC lead needs to be isolated when using an external BEC or separate flight battery for powering the Rx. In a conversation with a Castle tech he indicated to me that a second ESC as in a twin application requires one of the ESC BEC's lead be isolated because it would be the same as injecting a separate battery or external BEC(2 voltage sources) in the mix.
So with Alpha's definitive comment on the subject, how would Motion advise a customer on using a Castle ESC on this bird as a replacement or upgrade? Just because FlightLine confirmed that the ESC manufacture says it's OK to plug both BEC's in parallel without risk doesn't change the fact that they didn't redesigned the technology to do this....... or did they?? Call me conservative when it comes to safe twin operations but am still gonna isolate one of the BEC leads because the ol' tech in me says so.
Best regards,

[AussieHoppy]

I too would very much like to know OV10's questions, particularly this...

...Just because FlightLine confirmed that the ESC manufacture says it's OK to plug both BEC's in parallel without risk doesn't change the fact that they didn't redesigned the technology to do this....... or did they?? Call me conservative when it comes to safe twin operations but am still gonna isolated one of the BEC leads because the ol' tech in me says so.
Best regards,

My electronics knowledge is amateur at best (if that even lol) but I know what happens when you inadvertantly plug in an nimh pack into the receiver without first removing the red bec volt supply wire... and with no technical knowledge I've assumed in the past that this is due to the bec's inability to cope with a voltage above and beyond the voltage it is supplying, perhaps?
Voltage is voltage, so I also don't understand why linear or switching would make a difference anyway? Or is linear more robust to coping with excess voltage being input?
While it is comforting to know things won't fry going by the multitude of test flights, but as OV mentioned, how many planes were involved? If it were 100 planes with 700 flights then that would be reasonably conclusive. But a handful of planes with a total of 700 flights may not be so conclusive perhaps?
So if it is the difference in input voltage that is smoke inducing (eg fully charged nimh @ say 6 volts + bec @ 5 volts), what would be the safe tolerance of input voltage variation from two sources before smoke happens? Is the esc/bec manufacturer stating the tolerance of their product is near perfect exact 5 volts supply, hence no issues when two bec supply wires are plugged in? If you are unlucky enough to end up with one bec supplying more than the other from factory, will this result in damage?
Personally I'll probably remove both red bec supply wires and run with either a seperate ubec or dedicated receiver battery pack, which is something I do with most of my planes larger than 1400mm, and particularly planes I truly don't want to lose, lots of servos, retracts etc.
This is very much a personal choice of course, and a choice born from past experience- not from any degree of electronics knowledge.

I'm certainly not stirring the pot, I'd really like to know & learn about dual voltage input with bec's... having the ability to plug two bec supplies into one receiver can only be a good thing, with redundancy in mind perhaps? One bec dies, the other would continue to supply 5 volts?
Feel free to pm me if this is deemed off topic/ beating a dead horse :-)

[2FewDaysAtFlyingField]

My last difference of perspective on this topic of BEC's in twin applications.
Am very curious as to the cause of the meltdown possibly being BEC related? If it is, then it becomes a 1 in 700(Alphas quote) failure statistic which is not very good and it may become even worse because of those 700 flights how many different aircraft were involved to get a sense of the number of ESC's actually tested.
With the above comment regarding CASTLE ESC's, every one of their device manuals whether it is the Talon or Phoenix indicates that the red wire on the BEC lead needs to be isolated when using an external BEC or separate flight battery for powering the Rx. In a conversation with a Castle tech he indicated to me that a second ESC as in a twin application requires one of the ESC BEC's lead be isolated because it would be the same as injecting a separate battery or external BEC(2 voltage sources) in the mix.
So with Alpha's definitive comment on the subject, how would Motion advise a customer on using a Castle ESC on this bird as a replacement or upgrade? Just because FlightLine confirmed that the ESC manufacture says it's OK to plug both BEC's in parallel without risk doesn't change the fact that they didn't redesigned the technology to do this....... or did they?? Call me conservative when it comes to safe twin operations but am still gonna isolated one of the BEC leads because the ol' tech in me says so.
Best regards,

In light of Alphas post above and after getting a chance to finally shake down all the servos in the system and troubleshoot my issue, it was a short in the front steering/rudder servo wire that probably caused all the excitement, NOT THE BEC's plugged together.

I systematically went through the following procedure:

1. Unplugged everything.
2. Plugged each ESC into the same battery and checked the BEC voltage to be Exactly 5.391 volts for each BEC. Therfore, there should be no reason they cannot be plugged together since the electrical potential between them is ZERO.
3. Plugged both ESC servo/throttle wires into a Futaba Y cable and plugged it into my Futaba 7008 receiver. Green light, no smoke.
4. Plugged every single servo into the receiver individually and actuated it. All servos but the steering servo worked perfectly. All lights appeared to work perfectly except the landing wing light looked pretty anemic. very dim compared to the others. May have to investigate that later.
5. Took the center pod off and voila. found the issue. I ran my wires under the center wing section (Contrary to recommendations on here but identical to the build video) and although I thought I was super careful, I ran one of the screws right through the hot and ground wires on the servo connection to the steering servo. BAD.
6. Cut the section out of the damaged wire, resoldered, heat shrunk each wire, heat shrunk the entire assembly and function checked it.
7. Will be running my wires from the front of the pod over the top of the center section per the recommendations on this forum.
8. Assembled it all (Again) and will need to order another Control Board from MotionRC if they ever find the box in that sea container that has them.

I'm not convinced that the control board smoked or whether the Aileron cable just happened to be next to the Futaba y cable wire and when it melted, it melted the control board cable. I could just de-solder the cable and put a new one on there but with 90% of the planes control function going through that little blue box, I think I'll wait for a new one from MotionRC!

Hope this clears up some concerns for everyone. I see no reason why anyone should be concerned with the BEC's shoved together. I won't be removing a red wire on either of my ESC's on this model regardless of my electrical issues with this particular bird. I've never run a screw through a servo wire in my 25 years of modeling so I guess it was about time!

[AussieHoppy]

Whew, nice to know.
Pity that happened to you none-the-less, but good to know the cause.

[TSHobbies]

Got mine operational today...and I can tell you...now I know why this plane had lights on the back of the center fuselage...theyre back up lights! for when dummies get the props mixed up..duh. oh, and to those who had asked earlier..2 4S 3300s Zippys will fit just fine..though I havent balanced it yet so gotta check that first.

[TiredIronGRB]

Been doing a little detailing waiting on my HotRod pinstriping guy to come do my nose art...



Painted the nose, haven't decided what to do with the spinners and cowl.



Cut some aluminum screen for the cowls, will probably do some for the rear air intakes as well.





Like most kits the guns come with solid ends so I drilled them out.



Went to Lowes and matched the paint colors, the sample paint comes in a low sheen which matches nicely.



Nice fit.

[Aros]

A man after my own heart, putting screens inside the cowls! That is what I did to my Legend Models P-38 and was planning on doing the same with this one. Nice detail work! Bravo.

And yes do the radiator intakes too! Don't short change me now! LOL

[Aros]

...I ran my wires under the center wing section (Contrary to recommendations on here but identical to the build video)...

...Will be running my wires from the front of the pod over the top of the center section per the recommendations on this forum...

Glad you found the cause but I am confused...What is recommended in this thread (running wires-wise) instead of the build video? I want to make sure I am not using something from the video I shouldn't be?

EDIT: Oh wait, I see you say identical to the build video...My bad...Whew, thought I was missing something. :)

[Grossman56]

I must not read this thread any more! I can't buy another airplane!! I must not read this thread any more! I can't buy another airplane!! I must not read this thread any more! I can't buy another airplane!!.....................
Grossman56

[Grossman56]

I wonder how the boys are doing with their builds, just a peak can't hurt, can it!?

Grossman56