Greg, sorry about your Spitfire.

[Papa]

I understand your Kyosho Spitfire went down on it's maiden.
Sorry to hear that but I'm curious to know if a cause has been found.
I understand you used an Orange Rx.
How many servos were there and did you use a separate UBEC?
I'm a little suspicious of the voltage tolerance for these Rx's.
I had a Futaba version ($29 bucks) on the work bench and it burned out with about 8 volts.
Have you checked the RX to see if it is still working?

Don't want to prolong the agony but if we can learn something from the experience then we all gain.

Jack.

[Gregor77]

Here is the details of the build:

HK SK Series 50/55 1450 kv turnigy motor (good for 4-8 Cell)
HK 80A plush ESC with build in UBEC (3-8 cell)
HK 4S 3600 pack 30C
HK Orange RX
HS 6 Servos 4 std, one Futaba for flaps and one HS for Retracts

Glen commented that it seemed to reduce power and then he had no control.  She then nosed in.

When we got to the plane, the RX was quickly flashing orange.   After some research online, it mentioned this means power lose or lose of bind and the RX reset but could not bind to the TX.   

There are some senario's. 

1) lost connection to the battery?
2) Too much current draw from the motor?
3) RX failed?
4) UBEC failed.

I did a quick test at home last night and the motor worked.   But I will run it longer and see if it loses power again.   But for now, no answer.  Just sucks...  I didn't even get to try it out?   The rest of the planes came home in one piece... 

[Papa]

I wonder about the built-in UBEC. I think it is better to use a separate battery and UBEC for more than 4 servos. Having said that my P-51B does not have a separate UBEC because I have a CC ICE ESC that will handle the load. I used a separate UBEC with my Mentor and never had a problem, mind you it only had 4 servos.

Jack.

[Gregor77]

I did some tests when I got home... It all worked?  I had all the servos plugged in and ran the motor at 100%, the esc didn't get warm.  I moved everything and I even walked to the park and attached a stick to the servos and saw it moving...   I am stumped?     

It must have just simply lost bind?   The TX was at 4.9 when it failed.. could the TX have not had enough signal?

I am now putting everything (less RX) into a pawnee that has 6 servos?  Is this going to be the same issue again?

[Gregor77]

The more I read up on this, it could have been the UBEC.  It is only good for 4 std servos from 3A to 5V output.   Due to the fact the plane had 6 servos (std size) the built in UBEC may have not had enough power and cut out.  They said it is good for 4 STD servos only and the RX.  Well before it goes in another plane, I will ad a separate UBEC that can accomodate 6 servos.    it sould have been nice if the instuctions stated that!   

[thehaze]

Sorry to hear about your crash Greg. I lost my Mini Pulse on Tuesday when almost the same thing happened. I was turning upwind over the north end of field when I lost all control and the plane dove into the ground, the plane was totaled. When i inpected the wreck the rx was flashing indicating that it had lost signal. I was using a spektrum 6100e so it would appear that the orange rx is not the only ones to fail in this way. The electronics were the stock eflite ones (the model was a pnp version) so I don't think the setup was the issue.

I'm pretty much stumped.

[Gregor77]

I had a talk with John and he said that the stock UBEC from the 80A plush was not enough to run all the std servos and the voltage dropped too low and caused the RX to run low.  Causing the mis bind.   After reading all the forums, they said MAX is four STD servos at 3A/5V.  If it was mini servo's, I can do 6.   

So I have to change my built in UBEC to extenal UBEC for larger planes.  My Miss America only has 4 STD servos and an external UBEC with a 100 AMP esc.

I am now a bit scared.

[Papa]

I would suggest separate UBEC's for anything over 4 servos regardless of size. It's the draw that's important.

As an alternate avoid the black hole in the north east where the aliens live. They are angry at being disturbed by the road construction. As evidence I offer the strange erratic winds that are blowing most afternoons. It's those aliens huffing and puffing over the noise.

Jack.

[Gregor77]

With all Joking aside (but I think Jack is right)   ...

This incident brings up a good point....

With alot of newer people entering the hobby, I think it would be wise to have some more experienced people review the planes prior to any maidens.   I will be honest and was not even aware that this could have been an issue.  My "plane" building is limited to about a year of foam planes and med size aircraft.  If at some point someone mentioned this, I would have accomodated.  But was not aware.   I have now learned a costly lesson.   The only postive side is that I didn't try this by myself and could have ended up hitting someone.    For in the future, I would like someone to not only check my planes (control surfaces), but ask questions on electronics to make sure this stuff is safe and 99% reliable.

[flying saucer]

Yeah its good to have an experienced modeler check your plane out after a build, only thing is - some HK components are quite new, so it might be tricky to really have a clear idea on what will work best. Plus I find there are a lot of varying opinions on setups with certain components.

[pmackenzie]

FWIW, a simple test for a BEC is to just quickly wiggle all the controls, cycle the gear, raise and lower the flaps, etc.
If you can do that for 1 minute without the BEC overheating or any erratic servo motion you should be OK in the air.
If the servos stutter at all then you need to do something.

Peak current is usually in servo reversals since the motor has to go from full power in one direction to full power in another. Maximum sustained current would be from a stalled servo due to binding somewhere.

Dimension used to sell a handy little unit that told you a lot about the radio system requirements.
http://www.dimensionengineering.com/ServoSense.htm

In a pinch a wattmeter could at least tell you about sustained current draw.

Pat MacKenzie