modawg73
Posts: 53
Joined: 1/18/2008
From: Mason, OH, USA
Status: offline
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BigGuy,
I was using a Futaba 8uas with an 8 channel (I think it was a 148) futaba PPM (FM) receiver.
Then I switched to 2.4 Ghz by purchasing a Spektrum DSM2 Module to fit the 8u and a 9 channel DSM2 receiver. Still use the 8u, just broadcast on 2.4 spread spectrum.
(Btw, if anyone else does it that way, just watch out for how you wire the receiver. The first slot in the receiver is labeled "Throttle" which would correspond with channel 3 on the 8u. The second slot in the receiver is labeled "Aileron" which would correspond with channel 1 on the 8u. The third slot in the receiver is labeled "Elevator" which would correspond with channel 2 on the 8u. I called Horizon to ask them if the labels were correct (meaning that they had channel 3 in the first slot, channel 1 in the second, and channel 2 in the third.) They gave me the wrong answer on the phone. To work it correctly, you put the servos connected to the throttle in the spot labeled "Throttle" and so on.. apparently the module changes the channels when it broadcasts...kind of weird.)
I have two battery packs, 2400 mAh 5 cell NiMh, running through two heavy duty switches with a charge jack. They are mounted pretty close to the wing for balance sake.
Mounting the receiver, I put the main receiver on the space provided in the fuse just in front of the elevator servo, then I mounted the remote receiver in one of the holes next to the elevator servo. I glued on a small piece of plywood and attached the remote receiver such that it's antennas were pointing straight up and down (The yaw axis). So I have one antenna from the main receiver on the pitch axis, one from the main on the roll axis, and the two antennas on the remote receiver on the yaw axis. That way, the signal should always be received by at least two of them.
She flew rock solid on 2.4 Ghz.
On the FM, I always had some weird goings on. Nothing major, but I felt like I would take hits for a second at a time. It started when I was breaking in the engines on the ground. I did it in the bird, with the radio controlling the throttle. I would have weird noises coming from the bird intermittently. I wondered if it was being hit. One day at the field, I had the Tx turned on, the Rx turned on, and was trying to get one of the engines primed. I wasn't having luck, when all the sudden the tail waggled for a second, then stopped. 10 seconds later it did the same thing. After a third time, I shut it down. We looked for someone on my frequency (channel 29) and someone just started using channel 30, but that shouldn't be an issue.
The final time I flew it before switching, I felt like I lost control of her for a time. I guess i could have gotten disoriented, but it sure felt like it wasn't doing what I was asking her to do. On final approach, my engines revved up real high for about a half second without me doing that on the sticks. That was the last straw.
I am not sure if the issue is the twin aspect, or the routing of the antenna parallel and close to the elevator pushrod, or even a bad receiver. I pulled the receiver from a 1/4 scale cap 232 that I have flown for years, without ever having any similar issues, so I doubt it is that.
Whatever it was, the switch to 2.4 got rid of it.
Ken
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RE: New Hangar 9 B-25 - 
