1/3 scale Pitts

Hello all,
I am having inflight problems with my radio equiptment on a 1/3 scal pitts.
Hardware is: -
4 x JR 559 Digital servos
4 x JR 811 Digital servos (Ailerons)
JR 649 reciever
JR 9X Transmitter
INTAIRCO Whip antenna (19.5inches long)
2400 5cell NiCad battery
Desert Aircraft DA50 engine.
When I switch on the radio gear the system draws an average of 1 amp. This
should give me a comfortable 1 hour flighing time!
As soon as I start the engine the system draws approx 6 amps. This causes me
to get radio glitches after about 15minutes of operating time. The voltage
at the RX seems to drop below 4.5 volts.
Any ideas why the current draw would be so high with the engine running?
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Your first big problem is that you're drawing a full amp with the plane just sitting there. The idle current for your equipment shouldn't be anywhere near an amp. Forget the engine running for now, you need to fix that one amp draw first. I'd start from scratch and check the system by starting with the receiver only, and then plug in one servo at a time and see where you have a huge jump in current.
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thats the only good way.
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The 1 amp is when all the servos are moving. The idle current is about 200mah
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I noticed that there is only ONE battery in your equipment list. As this guys implies DO NOT run the engine on the RX pack, even if it is a 4000 mAh pack. You need to make sure that ALL the ignition system (module, switch, charge jack, AND ignition system battery pack) is at least 8 inches from any RX or servo.
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Yeah, i run a seperate battery for the ignition, however the throttle servo is on the fire wall about 2 inches away from the ignition unit.
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David AMA40795 / KC5UH
Here's an idea...
Have you tried measuring the current draw thro' a range of throttle settings on your engine? My idea being that your servos (which are high resolution and therefore will try and keep the surfaces still) may be fighting the vibration that's being transmitted down the airframe down to your moving surfaces.
Have you balanced your prop and spinner?
I'm in the process of putting together a big plane at the moment. It's going to have 2 digitals on the elevators with 120 degree throws. I think I'll measure the current draw of the servos with and without the engine running to see if there's a difference.
-- Philip Rawson
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Philip Rawson
WAY TOO CLOSE........not only that, but when you move the throttle back into the main fuse area where the rest of the radio is, make sure you use a push rod that is broken some where by a non conductor......i.e. a nyrod or some similar type push rod.
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Tom Minger

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