VinceY

My Feedback: (34)

Well, my 40% Exclusiv-Modellbau Katana went in last Sunday. It looks to be almost a complete loss. It was the second flight of the day, my batteries were freshly charged and everything was going well, until....I performed an outside snap on an upline. My speed was just above stalling. I actually let the plane stall after the snap and then pushed the rudder in for a hammerhead. On the downline I increased throttle and pulled level. Except the plane didn't pull level, it tucked under. I knew the plane was not responding to my request for up elevator, so I went with the plane and pushed. It gave me more down elevator and I completed an outside loop. All controls were responding except for the elevator. It seemed to be stuck 50% down. I could get more down elevator, but no up at all. I went through about 4 outside loops with each one getting smaller and lower. I kept thinking I would get elevator control back and boogie back to the runway. It didn't happen. On the 5th outside loop I cut the throttle and tried to roll upright before I got to the ground. It went out of sight behind a small hill in the field. When i got to the carnage my tail group and left wing were all that was intact. The cannisters were crushed, the motor won't turn, the headers were broken and the batteries were fifteen feet from the crash. The elevator halves were inline with the stabs and moved freely. They were powered by 2 Hitec 5945's each running through a Power Box Champion to a Futaba 149dp. I haven't hooked everything back up to see if the elevator halves deflect down. I just don't have the heart to open the trailer right now. I'll put some before and after pictures on here in a day or two.

Hooked-On-RC

My Feedback: (16)

Well I hate to say this and I know it will invite some controversy, but I had a similar thing happen to a pair of Hitec 5945's on elevators on an H9 Extra a while back. The difference being they locked up in flight, had no down elevator at all, yet had complete control of all other servos on the plane. Not sure what casued them to lock up, have had several opinions including voltage drop, loss of programming, interfearance, disconnection from receiver (which it was not), to any number of other issues. You will find a ton of information about 5945 troubles on this forum (as you will also find troubles with JR and Futaba and Airtronics as well) but not in the same proportions....Sorry to hear about your plane man, I know how it hurts.

Silvanskii

My Feedback: (17)

Did you try it on high rates?

If it did the same thing on high as well as low, I would say it's a shoe-in for servo issues.

Also, I assume that you disabled all the switches and dials that could potentially effect it to (dumb question but often overlooked).

Did you program them with the programmer, and did it have the latest software? Maybe there's something going on that Hitec doesn't know about.

Has the elevator ever fluttered before (however minor)? A continuous strain on the servos over a period of time could mess up the gears in them. Unlikely but possible.

The most info will come from when you do the (painful) task of going through the system and seeing what the 4 servos are doing now, assuming the crash didn't totally wreck them to. Make sure to trace the wiring if possible from the servos, alllll the way to the RX and look for any anomolies.

Diablo-RCU

My Feedback: (1)

The simultaneous electronic failure of elevator servos on both halves is highly unlikely. Yes, you could have one servo fail...that's possible. I would look to either a mechanical failure elsewhere, or a failure of a common component to the elevator servos (receiver, transmitter, or power box).

Did the servo horns slip (rotate) on the output shaft splines???

Tired Old Man

My Feedback: (1)

Silvanski,

I know you!! How's the infamous never do right aeronautical engineer doing?


If I read this thread correctly the conditions are ripe for another product bash. I'm NOT going there.

sillyness

My Feedback: (25)

Check to make sure the elevator pot in your TX didn't come loose.

Also, were all the elevators running off the elevator channel, or were the left and right sides split between mixed channels?

Were they programmed through your power box?

Sorry to hear about your loss... gives me a gut wrenching feeling.

VinceY

My Feedback: (34)

I don't want this to become a product bash. I'm just trying to get some other perspectives on the possible cause of crash. I flew one of my foamies right after the crash just to test the transmitter. I haven't tested my electronics yet, I've been working overtime to try to get another airframe. I too have a hard time believing four servos could all fail the same way at the same time. What is common to them is the power box and the receiver. Yes, I programmed the servos through the power box and they all came from the same channel on the receiver. The servo horns did not slip unless they slipped back on impact. The elevators were centered and moved normally when I got to the crash. I checked them first because I suspected mechanical failure.

Diablo-RCU

My Feedback: (1)

Is it possible that the incidence on either the wings or stabs changed in flight?

vatechguy3

My Feedback: (11)

there are some known problems with hitecs and futaba pcm receivers. if you look in the radio group you will see many threads.

what does the sticker on the servo case say?? it should be either a month and year or a trash can symbol.

thanks
tony

AirTech

My Feedback: (18)

I have seen major servo failures due to noise from the ignition system. In two occassion it has been caused by a slighlty loose spark plug in my ZDZ 40RV. In both instances ALL servos started acting wild with full excursions, and by reducing power, or killing the engine, the problem went away.

mglavin

My Feedback: (31)

I’m very sorry to hear of your model loss...

What’s interesting in the description of the flight prior to the models demise is the ability to utilize down elevator at your 50% defelction geusstimate plus... Sounds like the elevator channel may have lost its programming and the centering signal is not where it should be.

Is your Powerbox the model with on board servo programming?

What type, size and age are your batteries?

How were the servos coupled to the PowerBox, individual extensions all the way to the PowerBox for each servo or several extensions/connections on each servo or wyes?

Without resetting anything and with the TX on the appropriate model memory power up the components individually with known good components and attempt to isolate the problem.

Did you perform any kind of voltage and current measurements to eliminate voltage degradation, over driving surfaces or binding that contributes to excessive current draw and loads on the electrical system when the model was setup?

VinceY

My Feedback: (34)

The elevator servos had extensions soldered on-so no connectors. They were setup without the power box because the previous owner was flying it without one. I was not happy with the current draw from the servos fighting each other, so I added the box to fine tune everything. The batteries were Duralite 4000's and I am unsure of their age. Thanks.

mglavin

My Feedback: (31)

I would send the batteries to Duralite for an evaluation. Since these batteries are parallel-series wired or two pair of two 1800 or 2000mAh cells combined to realize 3600/4000mAh @ 7.4V, a single cell with diminished capacity can render half the battery useless unbeknownst to the user. So while the battery may appear to offer the required voltage under extreme loads they do not hold up to demands. If this were the case with one or both of your 4000mAh batteries; individually they would be good for around four amps sustained current draw and go flat when asked for more.

Do you load test the batteries individually with at least a 1.5A ESV?

You don't have any connectors in play with the elevator servos extensions and each servo has a dedicated servo extension form the PowerBox all the way to each servo?

T. Bob

My Feedback: (9)

Sorry about your loss


Ive heard of pot problems on Futabas Transmitters. (who hasn't had a pot problem; I had one in college)

I'm not sure why you guys buy those things.

YNOT

A buddy called me this week and he lost his 40% Extra becasue the power box took a crap in flight. I know of a couple of others that did not loose their birds, however discovered the power box not to be operating correctly.

Too bad, beauty of a airplane.

VinceY

My Feedback: (34)

Pics

VinceY

My Feedback: (34)

more

DKjens

My Feedback: (50)

Vince,
You make me cry by posting those pictures man. It really sounds like something with the power box. I know a person who has twin Rx and power box set up. He had one Rx go bad, saved the plane, replaced bad Rx with brand new one. Less than two weeks later, he had the other Rx go bad, again saved the plane, and replaced with brand new Rx. Not only I, but many other, suspect either power box, or Rx interference when connected to the same power box.

I am running single PCM receiver to a Smart-Fly Power-Expander, but I don't have enough hours on that setup yet, to want to post any kind of numbers.

Good luck with your next plane and setup. I know how it feels to loose one, I lost a 3.0m Extra300 in January to PCM lockout(JR), I fly Futaba now.

DKjens

zain

Vince
sorry for your loss. Hope you find the problem and fix it. The pictures show that the plane went in hard. How many flights did you have on the model.
zain

zain

I have a 28% extra do i need to use a powerbox and where can i buy one from.

sillyness

My Feedback: (25)

Noone needs a power box.

IMHO, they are a fad that will go away in the near future. There's nothing like taking all of the gear in your plane and plugging it into a single point of failure.

On 33% and bigger planes I use this setup:

2 RXs
2 Fromeco LiIons
2 Fromeco SuperReliaRegs with built-in fail-safe switches, at least 2 leads from each reg to its RX (standard RC plugs or only good for 3 amps MAX, and they get very hot at that load resulting is voltage drops and potential failure of the plug)

Now here's the key: A jumper witha fuse in series between the left and right RXs (any open channel). You are now protected from: Battery failure (keep whole plane), Reg/switch failure (keep whole plane), RX failure (keep 1/2 plane), short circuit (fuse blows, keep 1/2 plane). Planes are easily landable with 1/2 of the controls... many have been saved this way.

The key with this setup is that control and power are not centralized in the aircraft... it is distributeded throughout the system... no single points of failure except the TX.

bhall01

My Feedback: (4)

What is the purpose of the jumper between the Rx's? I've heard it mentioned before, but I can't seem to recall what the reasoning is versus just running the two receivers independently.

Just curious!


Oh - nevermind, I get it - 1 battery to each receiver, jumpering them together "shares" the batteries between the two receivers, the fuse would isolate you down to a single Rx and single battery in the event of a short..... got it. Just had to think about it some more!

Thanks - BJH

famousdave

My Feedback: (61)

VinceY - really sorry to hear about the loss,, man I'd be pulling my hair out over that one... It really sounds to me like a flight mode / program mix issue on the TX... like a switch stuck or was inadvertantly set.... or like Michael mentioned, you may have sank your battery rails below current... hitecs have been known to do some really crazy stuff below voltage / current (any servo for that matter) very odd it only effected one channel though..... I almost wonder if you have enough wire capacity going back to the servos....


Sillyness - you are right.. no one NEEDS a PB.. that is true .. but they are nice in certain installs. No one really needs dual RX either, but some use 'em some don't. I won't ever use dual receivers even though I have plenty of them sitting around. One thing is for sure ... a 28% plane never needs either option but when you start sinking $10K into a large plane the paranoia definitely gets the best of us all.... I do have a PB in my 33% Yak, it made for some very simple and elegant wiring as well as it solved several problems with locating multiple switches and battery leads and it removed weight! I like the PB, but I would debate the usefulness of the servo programming feature (I only use the plain Champion PB model), but like every other device.. there is always a chance for failure. The PB I have has two independent channels, processors and battery sources so really, its not a single source of failure. The outputs however (servo amps) are, but then again ... so is my RX. The Emcotech unit seems like a better way to go, but they are expensive and require 2 RXs... nice solution though.

My take is that when its time, its time... nothing we can do about it. We can have all the redundancy in the world, plan for everything and that's when someone trips over the plane in the pits or hits us mid-air and destroys it anyway. Can't hedge fate or crap luck! I just put 'em together, keep everything as simple and clean as possible, inspect often and fly the crap out of it... so far so good.. !

DP

mu2driver

My Feedback: (15)

Oh man im am sorry for your tragic loss....

I too know how it feels to loose something so nice...$$$

Get back as soon as you can