Spectrum compatibility

[juanes1969]

Robert:
I have a 33% SDmodels YAk that was outfitted with a DX-7 Spectrum radio. The plane had a good range check, and flew great for 5 minutes. I`ve been using SmartFly in all my giant scale airplanes without issue (30,33 and 35% YAKs and one 75cc extra) all of them with PCM radios. The plane in question was latter outfitted withnthe spectrum radio and after 5 minutes I was bringing it for a landing. The engine was just a tad above idle and turning to final. Then dissaster!! the plane did not respond to anything. Went in with the right wing and engine.
I`m trying to discard as many factors as I can ti find the problem, so I`ll give you my set up to see if I installed everything correctly.

The plane has 4 hitec 5985s on ailerons, 2 on elevators, 2 futaba 9153 on rudder ans 2 tower ts70 on engine controls. The receiver is a 7 chanel that comes with the DX-7 and to a SmartFly power xpander Sport. The power expander has two jumpers that connect to the SM Super Regulator and a single 5200mAh Li-Ion Denko battery is connected to the regulator. Everything is switched off by means of a pin-and-flag switch to the reg.
The power expander has 8 pigtails, so we connected the 7 that we needed and I tucked the one left over away under the PE.

I know how the SmartFly equipment works and have been using it for the last 2 and a half years with no issues what so ever. This plane had 47 flights with this set up, but with a PCM receiver. The crash was on the first flight with the 2.4GHz.
My question:
Is the pwer expander sport compatible with the spectrum receivers?
Could the "brown out" condition occurr with this set up?

As I said before, I`m just trying to find the answer to the possible cause of the crash, I know the regulator and power expander are not at fault because I know what they can do and they do it well and after the crash they were both checked and they are in goo working order.

Thanks in advance Robert,

John

[k3sui]

Did you follow Smart Fly's recommendation not to plug the Smart Fly power into the receivers power jack? That will cause the receiver to lose bind at random times.

[juanes1969]

Yes, I did. All the Power Expanders pig tails, except one with only a white wire, were connected to the 7 chanels of the receiver. The batery port of the Rx was empty.
John

[sweetpea]

Yes you could have a brown out, you could have lost the bind, you could have had shadowing of the RX's, you could have had interference.

Post crash inspections are always hard.

I would send in all your Smart-Fly gear to them just to rule out it didn't fail (highly unlikely but could have).

I would also send in your Spektrum gear.


How did you accomplish the range check?
Notice anything different there?
Were the batts salvagable? Have you cycled them to see what capacity they still hold?
Where were the antenna's placed in the plane?
How is your TX battery?
Did you accidently hit the bind button on the back of the radio while flying (using a transmitter tray?). That will reduce power

[juanes1969]

Hi sweetpea, the range test was good to go, we did it as the instructions on the manual, there was no alarmas in the range test.
The batteries had almost 4500mAh in them, they are ok, no punctures or anything. They were recharged and reaches the 8.4volts with a little less than 5100mAh.
The antenas on the main receiver were placed on the power expander, all wires were held down everywhere so they would not come near the antenas. The other receiver was placed to one side of the fuse at 90° to the first one, there was nothing close to this receiver.
The Tx battery is good, it had a full charge and voltage before the flight.
No transmiter tray. The plane was flying fine for 8 minutes, and in final aproach I had no control.
And for a fuse that was completely destroyed, all servo wires, battery wires and PE/reg wires, were all connected in their places. we just picked up all the wires and the equipment came right off the crash site. We turned everything on again and everything worked ok after the crash.

Any other thoughts?
John

[sweetpea]

How was failsafe set?

If it was set, do you feel the plane went into failsafe?

If it did then you can cross brownout off your list. If it did not feel like that, then you possibly had a brownout. Do you know if your RX is the updated version that blinks on brownouts?

[juanes1969]

The failsafe was set but it didn`t feel like it was in failsafe, the plane just kept banking to the right and down until it was almost vertical.
The receiver is brand new, it`s the second receiver i got for the radio, the original is in another airplane. This one was binded to the radio and installed on the plane. Everything seemed to work ok.
This new receiver does blink when it is being binded, I have not seen it when it is in brownout condition.

John

[mflander]

The ar7000 receiver only has smartsafe, which means it will hold the last known stick positions except for throttle.

[rrritchey]

Hi John,
Sorry about the loss. We have been flying using Skektrum, JR and Futaba 2.4GHz for almost 2 years now and have not experienced any problems here. We flew a DX-7 for almost a year testing all our new stuff, no issues. I really do not have any idea what could have happened. You can send the stuff in if you want me to check it.

[sweetpea]

I fly Smart-fly on all my planes as well with no problems on 2.4, sending in your gear is just to check that gear off as a possible problem

The brownout check is easy.

1. Turn on the radio
2. Turn on the RX (I prefer a switch inline on the battery)
3. Turn the power off to the RX but leave the TX on
4. Turn the RX back on. It should reconnect in approx 1sec or less and the lights on all RX's (including satellite) will blink until you power off the RX and TX together. If it takes longer than 1sec to reconnect and/or your lights do not blink then you have the old system. The upgrade is free by Horizon.

The brownout upgrade doesn't stop brownouts. What it does do......when you have a voltage spike (say from a binding servo) the RX will shut off when voltage is below its threshold. It will then reboot. It reconnects back to the original 2 freqs it was on so the reconnect is much faster.

This could have been your problem. 2.4 RX's are much more prone to voltage issues than PCM RX's were because they are more like a mini computer than just a solid state device. Since this was your first flight on 2.4 it leans toward that. Also I believe you were running only 1 battery (in this size plane that is common). Your battery might show voltage being fine but this is a case of something like a servo stealing voltage from the RX.

Of course with the SF powerexander you should not have seen that.

Again, its only a guess. There is truly no way to know exactly what happened. All you can do is start from the beginning and rule out things that could have failed. You may have just got interference and yes that can happen even on 2.4

[smokin]

thanks for the brownout tech check list sweetpea! i wasn't sure how to check my system for the New or Old components.

[flying skunks]

all I use is Spectrum and SmartFly products in all of my planes with no issues.I even have the same set-up in my sons plane and no issues ,you had to of had a "brownout".