extremejets

My Feedback: (10)

Just wondering if anyone out there has had a problem with the Cortex Gyro (Failure). I came close to Loosing my Giant JL Yak 130 after 8 flights, I am using Spectrum AR12120 Receiver with A123 Life battery's 2@ (3100MA) all of my servos have less than .12 AMPS showing no binding. Just curious if anyone has had a similar failure ? the gyro is completely cooked? Strong electrical smell. I have these Gyros on my other jets and have had no problems up till now....Many Thanks.....

Len Todd

Your servo current readings seem high. Are those readings at idle? Mine typically are .001 to .003 at idle. (The flap servo may typically be more as it is being held up tight against the wing. But it unloads some in flight and I use half flap position on the ground.) I would be be working on that linkage or surfaces to get the readings lower. If these are truly the minimal readings you can get, they are significant and need to be calculated into your overall power usage (i.e. The current used during eight starts and taxis, etc. would be significant.)

Unless you have a lab grade meter with peak recording, your current meter is most-likely NOT fast enough to read peak current usage. A servo momentarily uses a lot of current to begin and stop the movement. It also uses a lot of current, which is consistent enough to fairly accurately read, to hold a control surface when the plane is moving. But at best you would be seeing an average current use, even if you recorded it in flight. HV Digital servos use a lot of current. I am assuming you are at least using Digital servos. In giants with digital servos, 5 Amps is a good number for momentary peak calcs. It is the peaks that you can not see. It is the peaks that cause electronic components to fail. Also, with digital servos, the calculated potential current usage is cumulative (i.e. they can all move at the same time unlike analog servos).

How many flights were actually on the batteries? Eight flights is a lot, especially when you have high servo current readings. Mah in a battery means little after 30-40% is used. I still have 60% of the Mah in my Jet's ECU battery and the thing will not start because the battery will not consistently deliver the current. Do not believe that your battery will consistently deliver rated current after it is 40% used. Some batteries may. Some won't. We tested and proved that this year.

Are you using a power distribution system? If you are using digital servos, the peaks can be up to 5 amps and all can be drawing at the same time. Getting all that current thru a Rxer bus w/o a significant voltage drop is not likely. Consequently, you could be seeing significant momentary voltage drops. You may want to consider look into a power distribution system. If you are not using one, you may also want to consider doing more reading about power usage in giants. Try the smartfly or powerbox sites for some added info. Some folks get away without using these. But in Giant Planes the power consumption is very high, at times. Counting on that Rxer bus to handle that load as well as all the other devices we could hang off it is not wise.

Another question to ask is: How was the Gyro wired? If it is drawing its power off a receiver after 8 flights on the rxer battery, it too is subject to any momentary voltage drop caused by all the servos. Then again, ... The Gyro could have just failed. But, ... the voltage could also have gone low on you after the 8 flights to cause this failure. Anyway, ... any optional device you add increases the risk of failure. Being a single failure device, I avoid gyros in giants. I have two of them in my junk box that came off used planes I bought.

melvin

My Feedback: (3)

I don't think he meant that he had 8 flights on one battery charge.

afterburner

My Feedback: (18)

Len, are you saying your high torque digital servos(I'm assuming that's what you are using) are only pulling 1 to 3 milliamps with the surfaces hooked up? What are you measuring that with? Just curious.

Len Todd

I initially figured it that way too. Then, ... I thought about some of guys that I have flown with in the past.

2walla

My Feedback: (10)

Your batteries and receiver can easily pass 30 amps into a box that only will handle 10 amps continuous. When i tested some jr 8711 they would pull 5 amps not even starting to work hard..One stalled servo or a shorted pair of wires could have caused it to burn up. I would keep looking at the rest of the equipment in the plane. Most likely something else is going bad and the cortex was the weakest link

Len Todd

That is correct. I typically use a Hanger 9 current/voltage meter, unless I have problems. Then I go with one of my test instruments. My measurements are typically at the servo connection.

I run all HV MGed servos at 7.3 - 7.4 VDC regulated. They are faster and more powerful at the higher voltages. Even the 35% Extra's idle currents are down that low and that has huge ailerons, but there are two servos on each aile.

My Sprint's flap at full up was at .080 amp last time I checked. Drove me nuts trying to get that down. I even re-hinged the flap trying to get it down. Maybe, ... I am too picky?

wojtek

My Feedback: (73)

when not using a power management system, you can always bypass the power direct to the servos from the RX, and just run signal and a ground into the Cortex. If you do this, then you are limited by the load capacity of the RX ( which is not much higher however than the gyro ) This takes a little wire juggling, but it takes the load off of the gyro. I have one plane set up like this .. another I am going into a powerbox so load is not an issue .



Voy

extremejets

My Feedback: (10)

My jet is new, I only have a total of eight flights on it? Eight flights on the new cortex! My batterys were safely getting me three flights per charge with little usage. All of my servos with amp. Meter showing less than .001 to .004 I believe the Cortex is good up to 10 Amps continuous with 5 servos.. Thoughts pls..

BarracudaHockey

My Feedback: (11)

My first thought is to talk to Danny at Demon Aero

jws_aces

My Feedback: (33)

I am flying the same receiver and starting out flying my Skygate Hawk using 2 of 3600MAH life batteries. I have about 25 to 30 flights on it with cortex. I check the batteries after every flight. I would swap them out after 2 to 3 flights with freshly charged ones. I am using 8711 all the way around including gear doors. I haven't seen any issues at all yet.

I now use the 4500MAH batteries and can fly up to 5 times before seeing 40% of battery loss. I also fly with telemetry and have alarms on the RX and Turbine voltage. I am sure I could a lot longer but I see no reason to take the chances. I keep batteries charged and ready for every flight.

I not sure what cause your problem and I glad you didn't loose the jet. Please let us know if figure out what happened.

F1 Rocket

Please give me a call so we can figure out what happened.

Danny
407-687-3126

flycatch

My Feedback: (26)

Contact LAjetguy here on RCUniverse. for support.

BarracudaHockey

My Feedback: (11)

So the distributor for the Cortex said contact him and you suggest he contact someone else for support?

mr_matt

My Feedback: (10)

Were the Cortex traces burnt? Were the servos still operating? Scary.

flycatch

My Feedback: (26)

The individual is a field representative for the distributor. If you want the truth I prefer going to the hands on guy.

BarracudaHockey

My Feedback: (11)

LOL

Danny is as hands on as you can get.

rcjets_63

My Feedback: (4)

Glad to see that you are working with Danny on this.

I have these gyros on all my jets and am a rep as well. I've never seen one fail so I'd like to know more about how survivable the failure was. Can you give us a better idea of what happened. When did you first notice a problem? Was it upon powering up, or in the air (in other words erratic/wild performance and the landing was a miracle save), or after taxiing back in and opening the hatch to shut off the receiver (with no apparent loss of control). You wrote the "gyro is completely cooked?", is that a question or a statement? Do you have any pics?

Glad your YAK is safe,

Jim

stevekott

Yes It would be of great help to find out if the traces accross the +/- bus cooked or any of the actual logic and control components upstream. Which components are cooked?

That would shed some light if it was a downstream current issue with the servos or a problem with the Cortex itself.

Any signs of melted or distorted wires, discolored servo terminals or jumpy servos?

Thanks,

Steve

LA jetguy

I have 7 cortex gyros in my jets and have setup over 10 for other pilots.... NONE have failed and all have performed flawlessly...

Danny is very knowledgable and can assist... He has offered his direct number to be contacted. RCjets_63 (Jim) or my self are both available as well to assist. My personal email is [email protected]..

Please let either of us know "exactly" what happened so we can help..

David

David Gladwin

If you guys want to know EXACTLY what is going on in your models, buy or borrow a Weatronics Gizmo receiver. This device records , amongst many other parameters, voltage and amperage at .1 second intervals for highly detailed analysis after your flight (s), rather like a quick access recorder as fitted to many fullsize jets. Real information, no more guesswork or assumptions !

This is an invaluable tool and has, for me, blown away many of the urban myths about power requirements for large model aircraft.

In addition, the 8 regulators are short circuit proof and divided amongst the servo banks to give a total delivery of upto 40 amps.

I have a couple of Airworld Hawks with multiple (11) JR 8711 servos, average current draw in flight is around 3.5 amps with very short spikes upto about 9 amps total, usually caused by large servo movements on the stab. or flap selection.

Need gyros? Just use the software to assign a gyro function to any channel from any axis !

David. G.

(NOT a Wea rep. )

LA jetguy

Danny has been in contact with "extremejets" (Randy) and the issue is being addressed.

extremejets

My Feedback: (10)

Guy's I am speaking to Danny directly when I find any more news will let you know. As of now I have gone thru my jet completely checked each individual control surface and servos . All servos are fine ,all wiring & connections excellent all servos pulling a normal idle load no binding at all. I will say that all of my equipment that I use is all high end with no short cuts. I have used Cortex Gyros on all of my jets with no problems whatsoever , At this time I do not want to jump to conclusions for this has been an extremely good product but it is the lifeline to your jets Longevity inflight? I noticed the failure when attempting my 9th flight on this jet and had to rebind my AR12120 spectrum receiver 4 times to take the bind? All antennas working? Finally a successful bind but out of daylight so I decided to call it quits for the day Lucky thing? Got to the shop unloaded the Yak 130 connected battery's for I wanted to drop my gear and noticed Cortex Gyro light not powered No stab power , no. Aileron power , no Rudder ? Checked wires no problem pulled cortex out and noticed a strong electrical burn smell! all pins straight no wire were burned but the Cortex unit was dead. This is all I can tell you guys at this time? Could be one bad cortex in the batch? Will keep you informed, it might be worth checking yours out to be safe (Sniff Check)....

jetpilot

My Feedback: (48)

I sniff everything before hittin it or flying it!
Scott

afterburner

My Feedback: (18)

Said the blind man at the sushi bar In the pilots lounge.