Futaba vs Spektrum

[octagon]

Hi Guys,
I have heard rumblings since I got back into the hobby about Spektrum radio systems and their apparent lack of sophistication when it comes to frequency jumping. I will be the first to admit to a pilot error crash, but I have had 2 crashes that could only be attributed to losing radio contact with the plane. I use a DX9 that overall I am happy with, but now that I am building bigger planes that cost A LOT more money, I am wondering about a switch to Futaba, specifically the 10jh . I wonder if anyone out there has any input on the idea? I do know that back in the day, Futaba was considered the best one could get.  Anybody using one of these TXs?

[deltawing]

I crashed many times too, but each time was my bad.

The fact is too many pilots crashed their electric planes because of the #1 brown out issue, some blame on the radio and doesn't realize that they forget to straight out the receiver antenna or badly position the RX behind the battery!  For larger planes one should always use a satellite receiver to archive better reception.
Mind you that we have big micro wave and cellular transmitters right next to our TEMAC field.  There are couple microwave transmitter antennas (the two round one) pointing to North/East and South/East directions and its paths cut through part of our flying zone. Those microwave round antennas are point to point that means a very high energy bean 1-10Ghz wave are sending out on the direction it pointed to.  If our plane fall in the bean direction the 2.4Ghz receiver will be jammed by the much much stronger signal even it will not recognize what it is. This short period of jam will stops or screw up all the channels, ends up losing control for couple seconds.

Next time when someone's plane crash, evaluate whether it is on the path (pointing direction) of one of those microwave antennas.

One way to reduce lose of signals in any circumstance are using satellite receiver(s) and very important fully extend those one inch antenna wire(s), don't let it curve around.  RX antenna should be position vertically if possible, if not, inline with the wing but not inline with the fuselage. If there is a second antenna wire, it should be position 90 degree perpendicular to the first antenna.  The third one should be again perpendicular to the other two...

So will frequency hopping help on above situations? I doubted!

[octagon]

Thanks Phillip,
I will say that in both of my crashes that I blame on the radio on, I was using Orange DSM2 rxs (I don't use Orange anything anymore), so maybe you are right about those micro wave transmitters. I have been told that the Spektrum DSMX can chose to hop between 12 frequencies, while the Futaba has unlimited (or nearly unlimited) frequencies to choose from.  And yes, agreed, the satellite rx is the way to go with a valuable plane.

[Frank v B]

Andy and I have the brown-out problem solved.  72 Meg. 

The only problem I have had with 72 meg was when someone turned on their transmitter on the same channel at the first Dome Fly (10-12 years ago) and splatted my airplane (Pitts) and said "sorry" and walked away.

I do have four DX6's and one DX 5 and have experienced two brown-out situations with 2.4 and saved 2 airplanes belonging to others that had browned out in flight. 2.4 confuses the hell out of me.

re: "satellite rx is the way to go with a valuable plane."  No problem.   I don't have any valuable planes, especially after the first flight.

Rob, the only reasonably technical explanation would be from Pat MacKenzie.  The rest of us are just guessing.

Frank

[Wingnutz]

I'll throw in my $.02 in the hopes that someone who knows what they're talking about will shoot my theory down like a model suffering a radio failure.
My theory is based on my unscientific observations that all my radio failure crashes have occurred using a DSM2 receiver and usually at a nearby (to ROGO, not Bobcaygeon) GTA flying field in an area more urban than rural.
DX5, DX6, DX8 and DX9, have not changed the pattern, but changing to DSMX receivers has and regardless of whether the receivers were Orange, Lemon or Spektrum, I have not had a radio failure crash since switching to DSMX.
My conclusion that DSM2 is the culprit is probably premature and maybe part of the explanation lies in improved battery and receiver management on my part.
Whatever the answer is I'd love someone to answer it once and for all.

[Crazyflyer]

Hi Rob, I got rid of my Spectrum, even with DSMX. Lost 3 planes and crashed too many quads due to brown outs.
I am very happy with my FrSky because it will warn me that my signal is getting weak (DSSI) and I can recover before going too far. And I haven't had brown out issues either.
I would suggest a transmitter with that type of telemetry if possible, it is even allowed me to find a model I lost in tall grass by seeing the signal strength on my transmitter.
I was also considering the Graupner MZ-24 12.

[deltawing]

Hi Rob,  Your DSMX is still a good investment. Obviously DSMX is far better than DSM2.   Make sure you are using DSMX Rx to takes advantage of the multi-frequency hopping and short recovery time associate with DX8/DX9.  if a DSM2 Rx is used with DX8/DX9 it will only fall back to DSM2 mode.  Most of the new Orange/Lemon/Spektrum DSMX Rx are true diversify Rx with two RF circuits and two antennas which allow easily positioning in 90 degree to each other to keep a stronger signal in varies directions far away. 

See this link for some explanation in simple terms. 
http://forum.flitetest.com/showthread.php?7931-The-difference-between-DSM2-vs-DSMX
Want more in technical explanations, just google it.

Many pilots do not realize that brown-out is the #1 reasons of crashing in electric planes. Gas pilots usually have no brown-out as they use a dedicated battery for servos and RX without the BL motor's extreme loading.  The fact is most build-in BEC only give 2-3A and that is why we get brown-out so easy.  Unless using a dedicated true good 5A, 8A BEC, otherwise watch out on the loading by all the servos. For bigger plane or one with many servos and retracts a good BEC is a must.
Use a watt meter to monitor the amperes it draws on a plane when all the servos are exercise crazily together.  Even with micro servos it might exceed 2A without loading.  What about mini and full size servos! What about with loading when the plane is flying?
The amperes draw will be easily double or triple under air loaded. End up the BEC drops below 3V.  Receiver stops working... plane crash!   my 2 cents.