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Old Jul 11, 2012, 11:26 AM
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Joined Jul 2012
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Help!
New Nine Eagles SP 228p stuck on full throttle

Hi,
I have been researching beginner helis on this forum and elsewhere and yesterday I got out my credit card and bought a Nine Eagles Solo Pro 228p. The new RTF package with the J5 transmitter.

After pre-flight check and hovering for 3-4 minutes total (in 2 sessions) I loose control, quickly power down on the TX and watch in horror as the heli bounces around on the ground like a breakdancing octopus for 20-30 seconds before finally hitting the concrete foundation of my house hard enough to rip the battery from the body.

Let's ignore the gory details of the physical damage for now. What is really disturbing is that as soon as I connect the battery the main motor is on "full throttle". At least enough throttle to make a significant pull on my hand.

- I have recharged the battery successfully after reading about someone having control issues with a funky battery.
- I have swathed off and disconnected the battery in the tx and tried again.
No difference.

Removing what is left of the canopy I can see that the RX unit does not show the red light indicating a connection to the TX and I see no indication os the gyros responding either.

Disconnecting the motor cable from the RX unit and then connecting the battery and all of a sudden the RX lights up after 2-3 seconds as it should and the gyros and tail motor all respond to input.

Disconnecting the battery and reconnecting the motor and I am bad to full throttle and no LED light again.

What is up?
Does anyone here recognize these symptoms at all?
Any ideas of how I can fix it?

Is it likely the initial hit broke the electronics and the crash is entirely my fault or is it more likely that the electronics failing caused the crash? I would have thought that the RX would stand up to a 3 feet crash but maybe not?

(I have spoken to the guys at the store and will bring it in for inspection tomorrow. So I will probably get some help with this from them.)

To counter the obvious beginner questions:
This is my first help and I am not an experienced helicopter "pilot". But I have flown helis before and can generally keep them in the air and perform simple maneuvering. I started on simulator way back in the 90s on the Amiga computer.

I would greatly appreciate any advice or suggestions.
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Last edited by eimer; Jul 11, 2012 at 12:17 PM. Reason: spelling error 23 seconds should have been 2-3 seconds
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Old Jul 11, 2012, 11:38 AM
Cranky old fart
Balr14's Avatar
Germantown, WI.
Joined Oct 2007
21,469 Posts
The all-in-one unit is damaged. It only takes a second or two of the main or tail motor meeting resistance to burn out FETs. If you don't cut power before you crash, odds are good that's what did it. The "chicken dance" means you didn't cut power. That could be due to a bad receiver or transmitter, and not your fault. Unfortuantely, unless it's a bad transmitter, it would be very hard to prove.
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Last edited by Balr14; Jul 11, 2012 at 11:47 AM.
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Old Jul 11, 2012, 12:08 PM
Crash and learn
United States, PA
Joined Dec 2011
1,605 Posts
Quote:
Originally Posted by eimer View Post
Disconnecting the motor cable from the RX unit and then connecting the battery and all of a sudden the RX lights up after 23 seconds as it should and the gyros and tail motor all respond to input.
My Solo Pro SP328a and SP100D appear to do a self-check when powered on and stop initializing if they find something wrong.

Since the tail motor follows throttle with main motor disconnected, your transmitter is working fine.

Yes, a shorted switching FET (transistor) that drives the main motor makes the motor run whenever the battery is connected.
.
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Old Jul 11, 2012, 12:22 PM
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Joined Jul 2012
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Thanks for the quick responses guys. Not too heartening but good info.
I am surprised that this would be "expected" behavior in such a small crash... small initially at least. Compared to the kind of damage smaller, and cheaper, indoor micro helis can sustain without any "electronic" problems I would had put this down purely to a faulty RX or some other quality issue at manufacturing.

We'll see how much the store wants to put this on me or the mfg tomorrow. As Balr14 writes, it is not easy to say wether faulty electronics caused the problem of if the electronics failed purely as a result of operator error. I do know I am very sure the throttle stick was at zero just before or at initial impact time and that the "chicken dance" kept going for at least 20 seconds.

I hope for their kindness or for at least for a ton of spare parts in stock.

Just out of curiosity and to prepare for new time (hope not). How go you handle a dancing helicopter if it is on a softer surface? I am not at all certain the battery would have been ripped out had I been in the middle of the lawn or somewhere similarly soft.
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Last edited by eimer; Jul 11, 2012 at 12:25 PM. Reason: added question...
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Old Jul 11, 2012, 12:26 PM
Cranky old fart
Balr14's Avatar
Germantown, WI.
Joined Oct 2007
21,469 Posts
The small micro helis have tiny motors that generate almost zero torque and run on 3.7v. There's not enough resistance or current to cause an overload.

The heli should never dance like that.
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Old Jul 11, 2012, 01:18 PM
Crash and learn
United States, PA
Joined Dec 2011
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Quote:
Originally Posted by eimer View Post
How go you handle a dancing helicopter if it is on a softer surface?
As a guess, you killed throttle and goosed it again just before impact, causing the main motor to stall while under power. Either the main motor is going to burn up or the switching FET will burn up.

You do not handle a dancing helicopter, you watch it die or throw a coat on it. SP228 has a 7.4v 1000mah LiPo, enough power to cut you if you interfere. You would not be so lucky with a larger helicopter or one with a higher head speed.
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Old Jul 11, 2012, 02:03 PM
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Joined Jul 2012
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And as far as I know that FET is integrated in the RX unit requiring a replacement of the whole thing (along with a few broken pieces of moving hardware).

I really wanted to save the poor thing from committing suicide but I am sensible enough not to try to pick it up. This was the reason I disconnected the motor at all. Not for any elimination purposes but simply to be able to connect the battery without repeatedly risking my fingers.

Maybe bring a jacket next time is a good idea

Thank you both for your insights.
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Old Jul 28, 2012, 12:00 PM
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Joined Jul 2012
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I just wanted to post an update with the conclusion of this "case".

My heli was accepted as a warranty case. The guy in the store said that this specific problem "only" affected 10% of all 228p's sold by them so far. To me, that sounded like a rather high percentage. Anyway. After about 2 weeks of waiting for parts, the store gave me a new 228p.

Now for the fun part. This new heli has so far not exhibited the same issue. However, this one is horribly balanced from the factory and just really poorly put together compared to the first one. I had to start tightening screws while the battery was on the first charge. Since I fully expected to tinker with the heli this is not a disaster but I would have preferred a few more minutes of "fun" before breaking out the tools.
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