[1bwana1]

Here is the report from today's testing, I am afraid this will get a little long, so please bare with me. We are still flying the 40% Carden Extra, because it is all wood, and we are reluctant to install in the ZN-Line Composite plane as this is a more difficult environment for 2.4. Today we had the additional remote RX bringing the total to 4 receivers. So the current setup is:

40% Carden Extra (all wood) This plane has years of flights on 72 MHZ with no issues
DA-150
30 X 10 Carbon Fiber prop
16 JR 8611 Servos with Match boxes
1 Fromeco 2400 for ignition
2 Fromeco 4800 for RX
3 HD switches
1 Smart-Fly Reg on ignition
2 Smart-Fly Regs on RX
All batteries, Regs, and switches have 16 gauge wires and Deans connectors for good power supply
Smart-Fly Power Expander Sport
R921 2.4 RX with 2 remote receivers
Spektrum Data Logger

The main RX is installed on a raised platform that was built to get the RX up high in the fuse and away from the fuel, tank, motor, wires and other things that might interfere with it. It sits in the normal spot on the power expander, which is mounted on the left side of the plane. The first satellite RX is mounted on the opposite side of the plane, and orientated 90 degrees to the main RX. The second satellite RX is mounted about 1/2 way between the canopy and tail. It is up high in the turtle deck, and orientated so that it is different from the other two RXs. We could see no way that all 4 RXs in three locations could be shadowed from the TX simultaneously.

For those who have never used the Spektrum Data Logger, it logs fades at each RX location, dropped frames, and holds. Here is how the data is referenced by the logger.

A = RX-1 in the main RX body
B = RX-2 in the Main RX body
L = Left remote RX
R = Right remote RX
F = Dropped frames
H = holds


After yesterday's good test we were very interested to get actual numbers from the data logger. We did a range test again, which looked good, and took off. A flight of about 14 minutes, including the IMAC Unlimited sequence was flown. Here is the data from the logger:

A = 255
B = 740
L = 509
R = 520
F = 304
H = 1

We were not sure what to expect, but still, we were not impressed with what these numbers were telling us. There are a lot of fades on all RX's, over 300 dropped frames, and 1 hold. It looked to us like we were on the ragged edge of losing the plane, so we decided not to fly any more until we figured out what these number actually indicate about the robustness of the system, and our installation. We realized that we had not re-set the RX between the range test (with the power reducing button pressed), and the flight. It seemed reasonable that there would be fades, dropped frames, and even a hold with the low TX power. So we decided to do more tests.

First we re-set the RX and did our range test again, exactly as before. Here is the data from that:

A = 255
B = 279
L = 275
R = 191
F = 310
H = 5 (much more here this time)

It seemed to us that this could account for almost all of the scary numbers from the first test. We reset the RX and walked the exact range test line again without the range test button pushed so we had full TX power. This time all data values were 0. Very encouraging!

We decided to fly a short 4 minute flight and check the data again. Here are the results:

A= 88
B= 109
L= 96
R= 184
F= 4
H= 0

It still looked like a lot of fades, but because there were so few dropped frames and no holds, we thought it looked like at no time were all RXs blocked at the same time. So we re-set the RX once again, and flew a full 14 minute flight, which included the IMAC Unlimited Sequence once again. Here are the results:

A= 255
B= 796
L= 829
R= 894
F= 132
H= 0

Unexpectedly, the fades were even worse than the first test. There were still a lot of dropped frames, but this time no Holds.

Because we really don't know what kind of numbers indicate a properly working system, we decided in the interest of caution, not to fly with this setup again, until we fully understand what is going on. Now the search begins for information that will allow us to properly interpret this data. We are not giving up on the system, it flew nice. However think about it, without seeing the data from the logger, the range check seemed to go well, and the plane flies great. If this data does indicate that the system is not properly optimized by our installation, we could have very easily lost the plane. There are many out there flying 2.4 without doing this kind of system testing. What are the ramifications of this? Surely, at the very least, people are losing planes unnecessarily. I guess we will know more as our understanding of the system grows.

I would really appreciate comments from anyone with real insight to this data. In the mean time, I am going to forward this report on to JR for their comments. I'll let you know what I learn.

-STEVE-