Official Freewing MiG-29 Fulcrum Twin 80mm Thread

[RC30Flyer]

My new tail feather wire routing... as far away from the ESCs and power wires as I could get. Made the extensions out of the same wire I use in my 30 and 40% aircraft.

[janmb]

There would certainly be civil liability in the USA (we have more lawyers than anyone else), and if the issue were known about beforehand, possible criminal negligence in the case that an out of control heavy object going 100mph or more hit an individual or vehicle.

And by definition, "out of control" means you have no control over where it crashes or what it hits.

It would be the same here in Norway. While the actual numbers you would be kept accountable for would be far more sane, we would definitely still be held accountable.

The insurance we have through our AMA equivalent is usually very good, but as all other insurance, requires responsible behavior on the part of the operator. Deliberately flying something you know/suspect have serious flaws would most certainly void the insurance coverage. (or more precisely, the insurance still covers damages, but in turn files a claim against you)

[Firebird]

Just opened the upper fuselage to get access to the cables and ESC‘s. We did know already that the elevator and ruder cables are bypassing the ESC.

Now I found the cables directly bypassing a set of 4 additional capacitors connected via 2cables to the ESC. With the 3 capacitors installed at the ESC, the elevator and rudder cable do bypass directly next to a total of 7capacitors. The 4 additional capacitors are not secured - they move free in this space with movement of the aircraft.

[janmb]

Just opened the upper fuselage to get access to the cables and ESC‘s. We did know already that the elevator and ruder cables are bypassing the ESC.

Now I found the cables directly bypassing a set of 4 additional capacitors connected via 2cables to the ESC. With the 3 capacitors installed at the ESC, the elevator and rudder cable do bypass directly next to a total of 7capacitors. The 4 additional capacitors are not secured - they move free in this space with movement of the aircraft.

Yeah, it's normal for setups using long DC lines to have extra caps.

Are the caps the real issue in terms of noise though?

[Firebird]

Yeah, it's normal for setups using long DC lines to have extra caps.

Are the caps the real issue in terms of noise though?

No, it is not unusual to have additional caps in long dc lines. But this additional caps are moving freely in this compartment - means the soldered connection might break after a while in flight. A failing capacitor could momentarily release a lot of electrical energy (directly next to the elevator and rudder signal line). This could cause the elevator and rudder pwm signal to be overpowered momentarily - causing the digital tail servos to enter fail save for a moment until the caps are discharged and the signal arrives clear again at the elevator servo.

[janmb]

No, it is not unusual to have additional caps in long dc lines. But this additional caps are moving freely in this compartment - means the soldered connection might break after a while in flight. A failing capacitor could momentarily release a lot of electrical energy (directly next to the elevator and rudder signal line). This could cause the elevator and rudder pwm signal to be overpowered momentarily - causing the digital tail servos to enter fail save for a moment until the caps are discharged and the signal arrives clear again at the elevator servo.

True enough. But that would not kill both sides simultaneously, like what we tend to see in the crash vids.

[Firebird]

True enough. But that would not kill both sides simultaneously, like what we tend to see in the crash vids.

The Y-cable and the ground line could spreads the distortion momentarily into both elevator cables causing both servos to enter fail save for a moment - even if only a cap on one side fails.

[GliderGuy]

Thanks - I have joined a number of others who are losing Mig 29s apparently. No, not using tailerons. Standard setup with 23g servos that were sent. I have details on the RCG thread and can provide them here as well. Only changes I made were 1) added a 20A castle Pro BEC 2) added two capacitors, each 3300 uF - one at the RX and one at the BB 3) used a 12 Channel Spektrum RX with 3 x sats 4) added 75mm JP ebrakes - powered direct from battery and 5) coated her with one coat of epoxy - which I do on all my models without a significant weight gain.

What’s y’all’s analysis of the setup? If the 3300 uF caps are added as RF filters to shunt noise, 3300 uF is going to have a low reactance/impedance and should kill noise....especially x2...up in the front area. But probably not impact noise at the rear.

No RF chokes and stock elevator pushrods and a high amp BEC....

What else may stand out? I can’t find the related RGC posts.

-GG

[Firebird]

Those of you who crashed - could you please check the 7 capacitor‘s of the ESC’s (4hanging at a cable next to the ESC and 3mounted at the ESC) on both sides of the aircraft for obvious damage (blown up, leaking, burned, swollen).

thanks!

[skybolt]

I had the 23g servos in the box with the Mig-29, Motion RC EU. replaced the faulty servo after viewing the video I made. https://www.youtube.com/watch?v=7FVVU5eiRPs&t=3s This was done with the supplied Y lead also checked individually with the same result. The replaced servo works fine. I would like to thank Motion-RC. EU for the excellent service.

[Captain MoMo]

Those of you who crashed - could you please check the 7 capacitor‘s of the ESC’s (4hanging at a cable next to the ESC and 3mounted at the ESC) on both sides of the aircraft for obvious damage (blown up, leaking, burned, swollen).

thanks!

I will check. Your concern is valid but I am not sure if this is a problem - Its worth a check.

[kallend]

Yeah, it's normal for setups using long DC lines to have extra caps.

Are the caps the real issue in terms of noise though?

Capacitors on the power lines at the ESC are to prevent damage to the ESC due to the inductance of long power lines carrying rapidly switched DC. I don't see it being a "noise" issue.

[Captain MoMo]

What’s y’all’s analysis of the setup? If the 3300 uF caps are added as RF filters to shunt noise, 3300 uF is going to have a low reactance/impedance and should kill noise....especially x2...up in the front area. But probably not impact noise at the rear.

No RF chokes and stock elevator pushrods and a high amp BEC....

What else may stand out? I can’t find the related RGC posts.

-GG

These caps are not added for RF noise. They are added as energy storage for instantaneous voltage dips - as voltage "shock absorbers".

[kallend]

Ah dangit. Now you've done it.

The FAA will see this and use it as an excuse to regulate us even more, and all the manufacturers will have to go through quality testing with friggen nasa or whatever in the name of "safety" and the "greater good", making a little 100$ foamy cost 1k.


Stop flying them before you crash into a puppy and it becomes a national story LMAO

I guess you've never had to deal with plaintiffs' lawyers.

[Firebird]

These caps are not added for RF noise. They are added as energy storage for instantaneous voltage dips - as voltage "shock absorbers".

exactly - and failing caps can discharge instantly a lot of electric energy. And those caps at the migs esc are lose in the little compartment - just hanging at a little wire (Right next to the elevator servo signal line)

[Evan D]

https://www.rcgroups.com/forums/poll...ts&pollid=7973

All the crashes that have added to the poll had the upgraded FW servos and the horns on the stabs were no altered/ modified.
Most had stock pushrods (two had modified the pushrods with better rods, ball links and carbon)
Most had the elevators going through the MCBe (two bypassed it)
Most had not balanced the stabs (two did)
Most were using the stock BEC (two upgraded)
Three used stock CG, three 10mm aft and one 15mm aft
Six think the cause was loss of pitch control and one thought it was because of the BEC

As more post we can collect more data.

My personal view point is that the chokes do nothing but add a placebo effect. Both ESCs have a capacitor pack that does help with the very long ESC to battery wires (I shortened those wires significantly). I really think it's a issue of just not enough servo power/ long thin extensions/ Y'ing them to a single connector (either the MCBe or the thin wire Y supplied in the update). I think a contributing factor is the pushrod/ angle to the servo/ low duty ball links.

What’s y’all’s analysis of the setup? If the 3300 uF caps are added as RF filters to shunt noise, 3300 uF is going to have a low reactance/impedance and should kill noise....especially x2...up in the front area. But probably not impact noise at the rear.

No RF chokes and stock elevator pushrods and a high amp BEC....

What else may stand out? I can’t find the related RGC posts.

-GG

[janmb]

Capacitors on the power lines at the ESC are to prevent damage to the ESC due to the inductance of long power lines carrying rapidly switched DC. I don't see it being a "noise" issue.

Precisely.

We had exactly the same setup in the A-10 as well - but the caps weren't tossing about freely there, they were stripped to the main leads.

[GliderGuy]

With regard to the RF chokes effects...

Before installing RF chokes: 1 crashed F-4 due to loss of control and 2 A-10 crashes due to loss of control (one repaired and a new RX installed).

Post RF chokes installation: 2+ years of flying and over 2000+ flights / F-4, AL37 and MiG without any loss of control.

Pretty solid data IMO. All of this on the same radio TX and RX type. Strong evidence of a positive impact from the chokes.

-GG

[Evan D]

I understand how you feel... And you do fly a lot to have a lot of data. As I said that was my opinion.

[bandetx]

A lot of the things we do to make our planes fly could be considered voodoo.