SPLIT S

I have a BH SR71 ( I know, I know ) and am in need of some help. I usually fly glow and kero, electrics are a bit of a mystery to me yet so I could use a bit of an education.

Over the weekend I installed my RX, powered it up and bound it. When I gave it throttle the right motor spun up ok, but the left lagged a bit. Finally started and seemed to be running in sync at full throttle. Closed the throttle and opened it again, the left lagged a second or so but then started up. I had about maybe 30 seconds of run time when I shut things down to take a look. When I unplugged the battery it was hot, not warm but hot. This is a battery I've used many times in other electrics I have. Put the battery in my ammo box, came back a little while later and it was puffed bad. Now junk.

I'm assuming there is a problem with the right motor esc or the motor itself. I don't know which or how to tell for that matter. I really like the SR and want to get it airborne. From what I have read in other threads it is a dog in the stock setup, some have gutted it and replaced the motors and esc's. The stock setup is with two brushless 3750kv motors with 30 amp escs. The attached picture shows this. Looking for advise on motors and escs, and even if I should be replacing the fans as well. Don't know if there is anything available that will mate to the fan housing supplied.

Thanks much,
Dan

ACES&8s

To set the ESC's throttle range turn on the TX and set the throttle to full. Power up the esc's rx and servos (hold the plane still just in case). wait for the first, initializing tone, then a second set of tones will start...move the stick to zero throttle. The ESC's will beep the cell count and then they're ready.

For the 64 mm fans the Cyclone motor here, might be something to inquire about.


http://www.pw-rc.com/product_info.ph...oducts_id/1750

I'm Not Experienced with anything but 70mm and 90mm, but I can say that most of the glass/nylon rotors are rated at 45,000 rpm or so.

A 3 cell on a 4500kv motor is 11.1 volts time 4500 rpm per volt equals 49,950, which is unloaded, so the actual rpm should be in the ballpark. Check out the balance of the rotors. If there is ANY vibration anywhere in the range of throttle from zero to midrange, BALANCE the rotor. You're going to push them. BE CAREFUL!

SPLIT S

Thanks for the advice. Worked on it a bit tonight, better but weird and strange things are going on.

First, when I power up the SR I get a four beep count from the motors, using a 3 cell pack. Doesn't make sense. I did what you said and the situation greatly improved, not perfect but very close.

I unplugged the battery, powered down the tx (JR9303) powered the tx back up, plugged the battery in. Now this is going to sound weird. I hit the gear switch and the suspect motor/esc started up at a slow idle. No crap. The other motor stayed off. Unplugged the battery, tx off, tx back on, battery plugged in. Everything worked.

Even more strange, as if it could, the motors respond to throttle input better with the gear down vs. up. I know, this makes no sense, but that is what is happening.

Unplugged everything, back in , taught the esc the throttle setting, rebound the tx/rx and things are better. I am at a loss. One time I power everything up it seems to work fine, another it doesn't. Another thing, during all of this after I had run the motors up I had everything still on. Battery in and tx on. The suspect esc beeped twice out of the blue, like I had just plugged the battery in. Interference - bad connection between the esc and motor????

Thoughts.... and no my workshop isn't haunted.

Dan

ACES&8s

I'd start from square one...wires, connectors, the y-connector on the esc rx channel...making certain of continuity. The ESC's signal line on the RX connector might be a place to look for a fault. Motor connectors too. Check for cold-solder joint...or a bad solder due to overheating.

If the problem persists, switch out the esc's into another motor.

Also, the ESC programming beeps may be online. The amnufacturer unknown you might search for a generic progamming pattern.

I'd plug the esc's into a battery one at a time, first to listen for cell count. Then power the ESC off, tx to full throttle power it back on. Listen for a long while, for the pattern(s). When they repeat you have an idea of the set mode. Usually the parameters are brake on/off, then maybe battery type nicad/lipo, then maybe soft start, then maybe timing, bit rate, etc.

For a cheapy generic, there are probably just three, batt type/brake/cutoff type

ACES&8s

On the fans, the Aussie guy Mark from Extreme-RC dot com dot au is the answer man. He can give you a better idea of *****g out the rotor rpm.
Also, if you ditch the stock motors, ditch the stock esc's