gmilo

My Feedback: (39)

Folks, I have a Behotec JB165 in my BVM F-16 PNP 1/6 jet. I have 3 other Behotec turbines, all JB220's and only the JB165 is demonstrating this idle flame-out problem. All are run from my same JR XG11 radio and same1131BPU receiver setup and same ECU 3S TP lipo 3300Mah 25C packs. What I'm experiencing is the JB165 after startup and full power check will SPORADICALLY flame out when I'm taxing for take-off and usually when I turn to line up for take-off and go down to flight idle. The ECU is reading out as normal, user termination (ie ECU thinks the TX /user is signally termination, low trim). The turbine has approximately 30 flights on it and on about flight 20 started to demonstrate the taxi out flame-out problem. I've tried 1) replacing the ECU battery 2) reteaching LearnRC 3) rebinding the receiver 4) adjusting minimum voltage idle from factory settings. 5) changed fuel lines and 6) replaced high flow UAT (BVM recommendation for this jet) and the sporadic flame out issues still persists. Runs great above idle with never an issue.

If any Behotec users have any ideas for what could be causing this, would love to hear from you.

Thanks

Greg

Len Todd

Taxiing flameouts I have seen are usually traced back to static buildup (Tire rubbing strut, excessively high fuel flow on tank filling, etc.) or a bad electrical connection.

Do you use anti-static additive? Have you tried spraying down the landing gear with anti-static spray. Slow down the filling pump.

Fuel pump electrical connections is where I would start looking if the anti-static precautions did not do the trick. It could be a bad pump too. I once had to replace an intermittent fuel pump only it was flaming out when you pulled the throttle from mid to-full speed back to idle, on the runway during taxi. ( it would flame out in the air too when you quickly pulled the throttle back to idle.)

gmilo

My Feedback: (39)

Thanks. I use Jetcat oil with antistatic additive. I haven't noticed/felt any static issues. My filling pump does run slow (jersey modeler with pump control speed). Will try antistatic spray as I haven't done this yet. Hadn't thought about changing the fuel pump, so thanks for the idea. It seems to always quite when I go down to flight idle after taxing with some power to take-off position. And I did have it flame out in the air last time out, but I was able to land off field in the grass without damage, gear up. I'm going to run the hell out of it on the ground before I fly it again trying to induce the failure.

Len Todd

The only other thing I can think of would be air in-leakage on the suction side. I once had a manual shutoff valve leak in around the stem. But that valve was on the suction side cause the pump was in the turbine cover.

That is all I can think of that could generically apply to your turbine. Good luck!

ww2birds

My Feedback: (14)

I had a similar issue with a Behotec 180GE ... but that was many years ago. Eventually went back to Germany and they replaced the ECU and the main fuel valve. Was never clear what actually caused it. Very frustrating so I hope you can isolate your issue.

Do you have your radio set up so that a failsafe really creates a failsafe on the ECU which it would report as such?

Over the years I've seen most people set the failsafe point to the same point as "off" (low throttle and low trim). This is AMA-legal, but you miss a piece of info.

If you go into the ATV menu on the throttle channel with the ECU on, and the data terminal plugged in, first note the position of "off" so you can go back to it .. then start increasing the travel below idle ... and note when the hand data terminal indicates a failsafe. Go to the failsafe screen with the throttle at this "way below off" position and set the failsafe position there. Then put the ATV back where it was...

Now you will see "user off" when you shut down the turbine, and "failsafe" if it's due to a momentary failsafe on the RX. No specific reason to think this is your problem but it would help to rule out one potential cause.

Dave

gmilo

My Feedback: (39)

Thanks Len David for your ideas. And ww2birds, I have eliminated the potential momentary RX failsafe root cause, but thanks for the feedback. Do you guys know of the ECU's are matched to a specific Turbine during testing/QC at the factory? Was thinking next step to try a new ECU if they are not factory matched and or a new pump. Or, I can just return everything to Behotec Germany and hope they can identify the RC.

bluelevel

My Feedback: (39)

Gmilo,

why don't you call or Email Thomas at Behotec? He speaks English fairly well and can be reached at +11 49 8131 80400. But please note that Germany is 9 hours ahead of you in CA.

Thomas

gmilo

My Feedback: (39)

I call and they don't answer the phones (and I understand the time zone difference) and have not responded to emails. Hence my efforts for forum feedback experience

Zeeb

My Feedback: (41)

I was thinking an electrical issue as I started reading your first post and the static deal was my first thought. If that doesn't do it, I'd start looking at the rest of the components as guys have suggested but I'd start with checking all the connections for corrosion, maybe even use some of that nifty cleaner the computer guys have for cleaning small electrical connectors. Fuel pump would be my next suspicion and the ECU probably last, but if you've got another on hand, I'd try swapping 'em out down the road a bit.

I do not believe that the engines and ECU's are "matched". The engines are test run at the factory and you get a run sheet with all the readouts which comes with a new engine, but I've not seen anything that would preclude using another ECU. As for getting ahold of Germany without much success, have you tried calling Ultimate Jets down in Texas? They are the USA importer/distributor for Behotec.

gmilo

My Feedback: (39)

Thanks Zeeb. I haven't called Ultimate Jets. I didn't buy it from them, so don't feel its right to piggy back off their tech support. I did buy it from Elite Aerosports and Scott has been very helpful with troubleshooting ideas.

Zeeb

My Feedback: (41)

Ah, well Oli is a bit touchy about supporting engines they didn't sell although I cannot see the reasoning behind that idea. Scott probably knows a whole lot more about turbines than lots of folks but you might want to try talking to Todd (Dreamworks), they've been playing with turbines for a long time, sell and service a number of brands now and IIRC, claim they can service almost anything.

Karsten022

Hello Greg,

please look at the following Thing:

I believe you have a Hornet III ECU. Please check the trim way on the Transmitter. If the way is to small and you push the stick to much to the idle direction you could turn off the Turbine.

If you go into the test menu you can see the way of the Transmitter in Milliseconds ( 0,8 to 1.9 MS) and in a number (1500 to 7500).
The difference of that number between Turbine off and Idle should be more than 600. If you push the stick to hard to idle the direction maybee that difference goes under 500 and this would turn off the turbine. I increase in my Transmitter the trim way to the Maximum what is possible and so I get a difference of 1000.

I hope you understand what I mean.

Best regards,
Karsten

David Gladwin

If anyone even suspects static problems, then bonding may be the answer. A couple of years ago, I had a flameout on lift off on a JetCat 180 powered Hawk. I have bonded landing gear to jet pipe to engine case. (battery negative). After refuelling I hold the landing gear , one hand , and then ground the aircraft, other hand , as a routine. Since then, no problems. I had also noticed some static shocks from my refuelling pump (Orbit) in certain conditions.

Bonding is cheap, easy to do and light !

Joe Dirr

My Feedback: (8)

Karsten,
Thanks for your post!
I have a Behotec 180 Gold edition, that is exhibiting the same symptoms and found that the 'steps / ms' between throttle trim low and throttle trim high were far too limiting; yielding a step range of only 476 steps.
I have a Futaba 18MZ incidentally.
The solution was to increase the 'percent of trim' for the throttle function from the factory default of 30% to 61%.
The result is that the throttle low trim is now 4209 steps / 1.0ms and the throttle high trim is 5164 steps / 1.3ms.
This gives me a step spread of 955 steps; well within the Behotec ecu parameters.

I haven't tested the turbine yet, but feel confident that the throttle trim parameter was out of limits and is now corrected.
Thanks again for your comments.
Joe D.

Joe Dirr

My Feedback: (8)

Guys,
I should also say that my Behotec 180 Gold was working fine for the first dozen flights without exhibiting any flame-out issues.

If the throttle trim step range proves to be the root cause, perhaps the narrow step range that I had was right on the border of shutting down the turbine with the throttle stick in the idle position; I can only speculate at this point.

And of course, time will tell if the problem has been corrected.

I plan to perform some taxi tests and then go ahead and fly the model.

I'll let you all know the results.
Joe D.

Zeeb

My Feedback: (41)

Just curious why you have the trim change on separate conditions?
I'm interested since I have one of the newer version Behotec 180's that replaced the Gold version and I fly it with a Futaba 18MZ. I've not noticed anything but that model has not been flown in quite awhile.

mauryr

What's the reason behind not using a switch to turn the engine off and on rather than the trim? I see many people still using this method and I would like to know what advantages it brings.
Thanks

Joe Dirr

My Feedback: (8)

Zeeb,
I typically, set up conditions or flight modes controlled by the three-position flap toggle switch.
This allows me to trim the aircraft separately for each of the conditions / flight modes, among many other programming functions.
I know you can do this through a program mix, but I prefer to use conditions or flight modes.
Incidentally, the throttle trim is the same for all conditions / flight modes, of course.
Also, I have to say I really like my 18MZ; it's so easy to program; love the color touch-screen!
Joe

Joe Dirr

My Feedback: (8)

Hi Mauryr,
Good question.
Using the trim to shut-down the turbine is the method I'm most familiar with.
However, I know that the Futaba 18MZ will allow me to assign the throttle trim to a toggle switch, without using an additional channel, but I haven't explored this method to date. I'll need to investigate to determine pros / cons of each method.
Joe D.

Zeeb

My Feedback: (41)

I just have the trim travel set to max per click, so it only takes a couple of clicks to move it from one end to the other, works great.
I may be suspicious but as an old guy, I want my radio setup to be as nearly identical on all models and all the tx's. I have one turbine on a JR 12X and I understand why guys liked the analog trim. The others are presently on the 18MZ, but the next one will go on the 18SZ because it fits my hands better.

Also, and this may be the biggest concern for me; what if someone else needs to shut down the turbine? Every turbine driver I know, uses the throttle trim to start/run/shut down.

CraigG

My Feedback: (40)

Good points Zeeb. Two other reasons I don't use a switch to shut down the turbine: Frequently not having a convenient spare switch and the possibility of bumping it off accidentally if I did. The 3 step digital trim works for me too.

Craig

mauryr

Personally I use the throttle cut function on my radio. Had it on the aurora 9, have it on the 18mz. This function automatically ignores the switch position if the throttle is above a certain point which you can set. What it does is to put your servo travel somewhere below 0 when you activate it. No need to play with mixes, trims or some other hack.
Have it on all models (including gas and electric) on the farthest away on the left side. Impossible to bump into while flying for me.
Also, this does not interfere with the trim shutdown: the lower throttle setting can still be reached by trimming down, if somebody needs to shutdown the engine and doesnt know about the switch!
On electric models it's very handy to prevent accidental run ups when bumping in the throttle stick while handling the model (which does happen, especially if you hang your tx like I do). Also useful to keep the motor running at idle even at 0 throttle if the model requires it (air braking effect on f3a and cooling setup for fans)

ww2birds

My Feedback: (14)

I like the JR-style analog trim on the throttle too. On the 18MZ, I set up the slider next to the throttle stick as the trim control for throttle and it works just the same way.

Dave

[email protected]

Moebius44

My Feedback: (1)

Curious; did you determine actual root cause?