Important Radio Issue
 

A year and a half ago, when I started to fly with Multiplex, I was astounded by the range I got with the Profi 4000 with the 9 ch IPD receiver (this was before the 12 ch was available). When doing a Lee Demary full antenna length check, I got more than 3500 feet of range with turbine off and running (there was a farmer’s fence and no easy way of going further, so I stopped there). This was over a hill so I could not even see the plane and it was sitting on the ground, not up on a non-conducting table. I was jubilant! Almost a year ago, however, I put the same radio with the new 12 ch RX in my HotSpot. Suddenly I had seriously reduced range. I convinced myself that all was fine due to several factors, but in the back of my mind, I was always concerned that I had a problem. Well, as we say in the space launch bidness, I had “go fever”. I wanted to fly no matter what. This is what killed the seven crew members of the Challenger. I ignored the warnings and rationalized the issue in my head and flew anyway. Many many flights in fact. Last Sunday, in preparation for my first Isobar III flight today, I was installing the Multiplex Royal digital servos that I was gonna use on the flaps. I had programmed them to be capable of 180 deg. of throw. While making the linkages I happen to brush my hand against on of the flap servos. It was red hot! I felt the other, same thing. I was horrified. It turns out that when programming the servos to be capable of 180 degrees of movement (according to the MPX service dude they are capable of 200 deg., but of course you gotta pay attention to where the center is), it is possible to run out of room and hit an internal servo mechanical limit. That is exactly what I had done on the Isobar and previously on the HotSpot’s speed brake servo. I hooked up an amp meter to check the servo draw and each digital was drawing OVER 1.25 AMPS, CONTINUOSLY!!!! Suddenly it occurred to me. Was it possible that my crappy range with the Spot was due to the fact that this huge current draw on the speed brake servo was pulling down my entire system’s voltage (two 1400 mah 6.0 volt ElectroDynamics packs)? It was indeed. I fixed the problem by programming the servos to a bit less throw. Today, before the new Isobar’s initial flight, we did the Demary range check once again. I am happy to report that all was fine and, once again, I had the best ground range of any system (and I’ve owned the big two) out there. I am a very lucky dude that I did not wreck a plane due to this. From now on I will always check current draw on servos after installing them. I believe Andy Low at Electrodynamics has a set up that he sells to do exactly that ( http://www.electrodynam.com/ ), or just make one up as I did.

Important Radio Issue
 

WOW. One lucky Dude !!!!! When that little voice is talking to you you should listen . It's easy to talk yourself into the easiest course of action ! I try to keep that in mind when I'm at work.

Important Radio Issue
 

Yeah, I am lucky. Its nice to know that I still have that horse shoe crammed up my behind!

Important Radio Issue
 

I have been to the runway where the 3500 foot test was done
and I was so impressed with that kind of range I purchased a
Profi 4000 right away. I mean 12 channels and range that
Futaba and JR can't even come close, its a very impressive
radio

Eddie Weeks
http://www.corpcomp.com/weeks1/

Important Radio Issue
 

where is the best place to get a profi 4000?
and can they be downloaded into a computer for saving setup details like jr's?

Important Radio Issue
 

I believe that you can buy directly from MPX USA, Electrodynamics, or from Darryl Usher Enterprises and several other distributors. Yes, they make software that allows you to transfer data to a PC.

New Isobar
 

And here's a shot of the brand new Isobar, before paint (Cajun camo), on it's first landing Saturday.

Important Radio Issue
 

A fly by.

Important Radio Issue
 

And a knife edge pass.

Battery Power-----
 

Bravo great thread, at lot of good insight into a bigger problem than we want to believe. --------

The I4C on board Digital volt meter is a permanent piece of equipment on board my turbine aircraft. With that meter (very sensitive) you can spot a servo hanging up or overloading. I think if more of us had a clear view of Battery power and load or voltage under load there would be many more dual redundant battery packs used.

The first time I became aware of the potential problem was a D/F StarFire I flew a few years ago. It had 15 servos and at first I only had one 4.8 volt battery pack. When I saw how fast the voltage dropped to 4.5 / 4.6 volts it scared the $&*% out of me.

I think you have isolated a problem that is probably more common than we all might think. It does make since that the effective range of the radio could be affected under extreme power drains.

Another situation that I think may come up more often than we might think is low volt / power for the ECU battery. Put a digital volt meter on that circuit and that to will become an eye opener.
With the Jet Cat when voltage drops to 7 volts the turbine automatically shuts off. All it takes is a weak or low battery to have that kind of flame out. The flame out can be confusing if you don't have a real time meter so you can spot the low voltage under high current pulls, like going to full throttle on a turbine. The pump motor draws it's maximum current at high throttle.

I just wonder how many aircraft in flight problems / crashes are directly related to battery problems ??

Important Radio Issue
 

Hey Guys,
What is the best way/device to check current draw on a completed plane? I have reason to believe a servo is binding in my plane but am unsure what the best procedure is to measure it the draw on the system.

Todd

Important Radio Issue
 

Todd, I just wired up my own adapter so that I can essentially put my amp meter in series with the current from either the battery or in line to a servo (if I wanna check just a servo). If you don't want to make your own, I believe that Andy Low at Electrodynamics makes a thingy for this.

Important Radio Issue
 

I just checked and Andy calls it the EDR-201 Eye Test. See http://www.electrodynam.com/catalog/C12-0608.pdf

JetCAT Low Battery Clarification
 

Just a note of clarification, the JetCAT will indeed shutdown at 1.0 V cell (the total voltage depends on the number of cells in the pack, you can run different cell counts with the JetCAT).

However, if you have not disabled battery checking, then you will get an inflight indication of low battery at 1.1 V cell (a throttle retard, not great but still an indication).

If you really want to get slick, you can set up a smoker system, and it will pulse the smoke to indicate either low battery, or low fuel state.

And another thing with the JetCAT you will absolutley know if a battery failure caused the shutdaown, just plug in the GSU after landing and look a tthe last shutdown condition.

Important Radio Issue
 

Whem my P-120 quit due to a low battery, the GSU would not show anything when we plugged it in. We had to unplug the battery and plug in another one in order for things to come to life. Will you still have the data from the flame-out flight if you do that?

Important Radio Issue
 

from page 8 of the V4 ECU manual addendum

Last-OffCond: Added to the list of states is PowerFail. This will occur if the power was lost because of a defective battery or connection or if the switch is turned off before the engine is shut-down. If this state is displayed, the Info Menu contains information from the previous run and not the current one.


I am not sure but I think this data is erased after the next good run, so you need to remember to check it before starting the turbine again.

Hope I got this right, I blew another diagnoses this morning!

I4C Products
 

I think the best and easiest way is to just plug in a I4C volt meter! They cost about $30 - $35 don't pull hardly any current themselves, are quick and easy to install and you can monitor them right up until you put the hatch on for flight. The I4C on board Digital volt meter is a permanent piece of equipment on board my turbine aircraft.

When you retract your flaps or cycle any servo in your airplane you can easily see if any servo is hanging up or overloading at the end points by watching the voltage drop and rise. The I4C shows voltage to the second decimal point. example 5.24v (very sensitive). It is easy to see if you are over driving a retract servo, flap or any servo installed in your airplane. As an example voltage will drop when retracting the flaps, but if you see the voltage drop even further when the flaps come to the full up position you know you've got a problem. Just go to your travel adj screen and back off the total travel, a little until voltage rises again. With a little practice you will come to recognize a high current drain servo easily. The most common problem servos are the ones like the retract servo, yes your gear work fine but are you actually overdriving the valve and don't even know it!! A small retract servo overdriving in the gear up position can draw more current than you think, maybe to to point of crashing your aircraft.
Lee H. DeMary
AMA 36099

JetCat Ecu
 

Guys,

The Jetcat ECU will save the last run data for display on the GSU even after power off and on,but will erase it when the engine is started.
The other detailed data(every 1 second ) for download via 232 adapter to a PC or laptop must be done before a power down or the info used for graphing will be erased. That kinda means a Laptop should be used.
What Lee is saying using a volt meter is a way of checking for amp draw,but should be done using an ammeter in series to checkfor amps. Voltage drop will only show on some volt meters if the draw is really excessive. The meter that Lee uses doesn't check the ECU battery status at all. The JetCat GSU can be used to determine Engine battery volts. Nothing can substitute for good battery cycling/charging and testing. That would have caught the battery showing just over 7.00 volts but with a bad cell that would go to very high resistance when the fuel pump amp was demand high.
The battery then would then basically go below 5 volts and the ECU would sign off. Batteries can fail in many varied ways and not at all predictable.
The Cat ECU is internally regulated to 5.0 volts. Bob has told me that he has (on the test cell) deliberately dropped a P-120 to 6.6 volts battery supply with the engine at full power with no problems.
I for one always charge the turbine pack between flights.
There was also was a T-33 that the engine would quit on every takeoff roll. The GSU showed "Power Fail". what was happening after much testing to determine the cause was that the receiver battery switch/harness would go open circuit when hosteled or vibrated.
This receiver power interruption was much less than a second but long enough for the ECU to see power cut to the receiver and turn off the turbine. At no time did we notice any radio dropout.
Lee and I now believe in 2 switches to the receiver with one or 2
batteries.
The 4.0 ver of the JetCat Ecu with its expanded troubleshooting allowed us to isolate and determine the cause of the flame out.



Nat

Re: JetCat Ecu
 

Nat I beg to differ with you, the I4C volt meter is very sensitive and will show the slightest voltage drop & current draw increase! While adjusting travel end points you can adj. down to 1 or 2 percent of movement, it really shows a binding setup on servo throws!

My experience tells me using the I4C unit installed on board you don't need an ammeter!! The I4C Products voltmeter does a great job. And for the I4C meter checking the ECU battery condition, Yes Nat, it can easily be wired to the ECU battery circuit. If you recall that is exactly how we found Bob's weak ECU battery at our rally! The I4C is a great tool and in my opinion should be used in all turbine installations -- you can install it in seconds, it's not expensive, and is very sensitive ----------
Lee -------

PS I have never seen anyone using an ammeter in line or other wise at the field, much less installed in a model aircraft. I'm not saying it wouldn't be better, just saying I've never have seen one used in a model ---------On the other hand I see the I4C in many installations, and it shows the slightest high current draw or low voltage situation --

Important Radio Issue
 

Lee....
More info on the IC4 and where it can be purcased please....

Thanks,
Todd

I4C Products
 

Hello Todd,
This little jewel of a voltmeter is made by:

I4C Products
6924 E. 92nd
Tulsa, OK 74133-5318
Tel 918-492-9435 Fax 918-492-9375
www.i4cproducts.com

I believe you should plug one of these voltmeters into any open port on your receiver (use a Y connector if all ports are full), also after an experience at our Jet Rally, (trouble shooting a turbine problem) I think we should have one of these wired into the ECU battery supply circuit. With these two indicators visible just before hatch lock down and flight they will add an extra layer of protection for battery related failures.
Lee H. DeMary
AMA 36099

PS Yes, trust your eyes, I did get the I4C screwed around sorry. I first posted IC4 I have since corrected my posts. The correct company name is I4C Products. If you can't find one of these at your local hobby shop, and want to support a hobby shop (and a good one) which has these in stock contact Jim or Carol @ Things with Wings 6268 W. 10th St. #2 Greeley, Colorado 80634 970-352-1067 Jim has them in stock!! They come wired for JR, Futaba, Airtronics, Hitec, AirtronicsZ. If the plug type you want is not in stock the Futaba style plug can easily be trimmed to fit perfect into JR.

Note, PiC below shows one only I4C, going to add a second for the ECU circuit. It's the small rectangle full screen display (green-ish screen color) voltmeter located just above my wheel brake pressure gage / air tank----------

Important Radio Issue
 

nat

i put an 8 cell turbin pac in so if i dropped a cell the turbine would not "see " low bat and shut down ( i told a turbine manufacturer over a year ago that i was doing it and now its standard equiptment with them)...........i always use a i4c volt meter on it ( and watch it on power ups ).....i also use 2 switches and 2 rx bats with one volt meter....i switch 1 on to read ( tugging on the elevator gimble)...turn it off and then the other....then with both on .....a binding or over traveling servo will show up on the meter.........why do i do it???to know my batteries and servos and to recognize when they are getting sick

gregg

Important Radio Issue
 

btw

i told wilcox about it and asked if i could do it with the jet cat......and he said absoluetly NOT....this was about 6 months ago....has that statement changed now??

gregg

radio problem
 

Gregg,
I know the Cat ECU is programmed for only a 6cell pack. There used to be an option for more cells but not now. I don't know the reason. Maybe Bob W will weigh in with some insight..

Nat

Important Radio Issue
 

PS I have never seen anyone using an ammeter in line or other wise at the field, much less installed in a model aircraft. I'm not saying it wouldn't be better, just saying I've never have seen one used in a model ---------On the other hand I see the I4C in many installations, and it shows the slightest high current draw or low voltage situation --

Lee,
Your comments on the C-Volt voltmeter are correct and many jets now have them installed for both ECU and receiver batterys. We are now testing our new Onboard Current Meter(amp meter). This instrument is the same small size as the C-Volt and will show live current continuously from turn-on to shut-down. See the exact current draw of each and then all servos by exercising them. This product will be ready for sale next month. Will be about $5 more retail than the C-Volt.

i4c Products
Rod Johnson