Intermittant MW44 Flameouts?
05-05-2008, 08:27 AM
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Intermittant MW44 Flameouts?
I was at the Mississippi Afterburner fly-in this weekend with Alan Cardash and his Nano Boomerang. We were only ones there with 44's and were both experiencing the same problem. We would get one flight in which they ran perfectly and then the next they would flameout. In fact, Alan lost his little Boomer when he did not realize it had stopped.
Mine is a 7 pounder with about 6 flights since it was serviced by Wren and his was a Gold that had also just come back from Wren. I was not using a UAT upon advice from Wren. Alan, however, was running his with one.
I was wondering if anyone else is experiencing the same problem and where we might look to determine what could cause the problem?
Thanks for any help.
Hal
Mine is a 7 pounder with about 6 flights since it was serviced by Wren and his was a Gold that had also just come back from Wren. I was not using a UAT upon advice from Wren. Alan, however, was running his with one.
I was wondering if anyone else is experiencing the same problem and where we might look to determine what could cause the problem?
Thanks for any help.
Hal
05-05-2008, 08:57 AM
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RE: Intermittant MW44 Flameouts?
We have an older 7lb 44 that does the same.
It will go 5 flights then flame out.
Mostly (luckily) on the take off roll.
It's done it for about 2 years
It will go 5 flights then flame out.
Mostly (luckily) on the take off roll.
It's done it for about 2 years
05-05-2008, 09:18 AM
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RE: Intermittant MW44 Flameouts?
Wren is closed for a holiday today...
Did the flame out happen on final when the throttle was pulled back to idle???
What is your deceleration delay value???
Shok,
After 5 flights...ECU battery recharged??
Did the flame out happen on final when the throttle was pulled back to idle???
What is your deceleration delay value???
Shok,
After 5 flights...ECU battery recharged??
05-05-2008, 10:40 AM
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RE: Intermittant MW44 Flameouts?
Mine flamed out on takeoff just after I made my turn. I was still at full throttle. I don't know what throttle setting Alan was at when his quit.
Also, after my successful flight as I was taxing back it would hardly respond at all. I would give it throttle and it would just sit there idling and then gradually run up to maybe 120,000.
Hal
Also, after my successful flight as I was taxing back it would hardly respond at all. I would give it throttle and it would just sit there idling and then gradually run up to maybe 120,000.
Hal
05-05-2008, 10:58 AM
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RE: Intermittant MW44 Flameouts?
I have 50 flights on my R44+ powered by the latest MW44 Gold. All have been just fine. I do use a BVM UAT. Still at all factory settings. 10 hours on the ECU. See below for shots of my setup.
http://www.rcuniverse.com/forum/m_6761370/tm.htm
Dave Rigotti
http://www.rcuniverse.com/forum/m_6761370/tm.htm
Dave Rigotti
05-05-2008, 02:33 PM
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RE: Intermittant MW44 Flameouts?
Gents,
Also having flameout problems with my Green '44 just 2nd flight back from a check up by Wren (inspection, flameout problems) who set it up with a new FADEC. I noted on the ground after the 1st flight that it would not return to idle rpm properly, sitting at about 80-90k for a prolonged period, with PW about 120, taking almost 3-4 minutes to return closer to idle (PW 108), when I shut it down at 60k. I had also run it from idle up to 195 k and back several times before the first flight, to be sure it had adjusted to the new throttle travel. It exhibited normal PW at idle and max rpm prior to the next flight. The flameout (Speed low) occurred at the end of the next flight, after throttling down on final (good place to quit). The Pulse width was 120.
One question I have always had is what is the proper cell count for the '44 FADEC battery? I use a 4 cell 1100 ma Nicad, fully charged usually 5.2-5.3 V before my first flights. At idle, the PW is about 110, but full throttle only 390 or so. The old FADEC manual indicated full power PW should be somewhat higher than 6-700. Does this indicate too much voltage, such that the range of PW is very small (390-110=280), and the FADEC-solving for the proper PW to output to the fuel pump-cannot alter the pump power with enough resolution towards idle? Has anyone tried to run the Green '44 on a 3 cell nicad, as they were originally equiped years ago? Perhaps Roger or Gavin could comment on this.
I remember there was some discussion of this flameout problem on return to idle by Gaspar, a number of years ago. He suggested using a couple of T fittings and making a bypass to return some fuel fuel from the pump outlet back to the inlet side, so the fuel pump ran with slightly higher PW at idle.
Also having flameout problems with my Green '44 just 2nd flight back from a check up by Wren (inspection, flameout problems) who set it up with a new FADEC. I noted on the ground after the 1st flight that it would not return to idle rpm properly, sitting at about 80-90k for a prolonged period, with PW about 120, taking almost 3-4 minutes to return closer to idle (PW 108), when I shut it down at 60k. I had also run it from idle up to 195 k and back several times before the first flight, to be sure it had adjusted to the new throttle travel. It exhibited normal PW at idle and max rpm prior to the next flight. The flameout (Speed low) occurred at the end of the next flight, after throttling down on final (good place to quit). The Pulse width was 120.
One question I have always had is what is the proper cell count for the '44 FADEC battery? I use a 4 cell 1100 ma Nicad, fully charged usually 5.2-5.3 V before my first flights. At idle, the PW is about 110, but full throttle only 390 or so. The old FADEC manual indicated full power PW should be somewhat higher than 6-700. Does this indicate too much voltage, such that the range of PW is very small (390-110=280), and the FADEC-solving for the proper PW to output to the fuel pump-cannot alter the pump power with enough resolution towards idle? Has anyone tried to run the Green '44 on a 3 cell nicad, as they were originally equiped years ago? Perhaps Roger or Gavin could comment on this.
I remember there was some discussion of this flameout problem on return to idle by Gaspar, a number of years ago. He suggested using a couple of T fittings and making a bypass to return some fuel fuel from the pump outlet back to the inlet side, so the fuel pump ran with slightly higher PW at idle.
05-05-2008, 03:02 PM
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RE: Intermittant MW44 Flameouts?
It would be very useful to know what the FADEC say on the "last power down cause", this will give us a clue of where to look.
After a flame out, just switch-off the fadec, switch on again, set trim to STOP (TrimLow on the screen) and then press the "menu down" button (first on the left). During 2 seconds the screen will display the shutdown cause, RPM, EGT and pump power at the moment that the fadec decided to shut down the pump (could be later than the real flameout occurred). This will help in to discard some things and concentrate on the real cause. Please post the 4 values (press the button as many times as necessary) so that we have the complete data.
Gaspar
05-05-2008, 03:56 PM
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RE: Intermittant MW44 Flameouts?
Thanks for your interest Gaspar.
My flame out on final showed SpeedLow T=288 RPM=34000 and PW=120. No bubbles in the lines.
I have had many similar flame outs before changing to the new FADEC. Most often throttling down, often a very slow settling down of the rpm to idle turns despite working well on idle/max/idle throttle excursions before beginning the flght. My Pump power at max rpm with the 4 cell nicad has always been about 400, idle PW about 110. The old FADEC had somehow had its cycle count changed/incorrect, and they thought it may have had some values/programming scrambled.
The way I read your Users manual V1.1, could the battery voltage be too high?
L. Turner
My flame out on final showed SpeedLow T=288 RPM=34000 and PW=120. No bubbles in the lines.
I have had many similar flame outs before changing to the new FADEC. Most often throttling down, often a very slow settling down of the rpm to idle turns despite working well on idle/max/idle throttle excursions before beginning the flght. My Pump power at max rpm with the 4 cell nicad has always been about 400, idle PW about 110. The old FADEC had somehow had its cycle count changed/incorrect, and they thought it may have had some values/programming scrambled.
The way I read your Users manual V1.1, could the battery voltage be too high?
L. Turner
05-05-2008, 04:58 PM
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RE: Intermittant MW44 Flameouts?
I have also had flameouts on one of my 44 gold engines. I only have a few flights on the engine and it has flamed out on almost every flight when returning to idle. I have also completed many ground runs to try and diagnose the problem and after changing the entire fuel system (thought I possibly had an air leak) I gave up and called Wren.
I was advised to slow down the deceleration delay and I have now changed this from 10 to 20 (from memory). This setting is now similar to my other Wren 44 and the engine has not flamed out since. I have however noticed it can be reluctant to return to its correct idle speed and will sometimes hang up around 80k. I hope this is because the fuel pump is new (sticky) and needs to settle down. For info my engine is a 44 gold (the new version) with a 7.4v Wren LiPo. As mentioned I have another 44 gold (exactly the same spec) and it has been faultless just like my 54MkIII.
If the idle speed issue goes away as the pump runs in then the change to the deceleration delay has fixed my little Wren If not I will take it back to Wren for some TLC.
I was advised to slow down the deceleration delay and I have now changed this from 10 to 20 (from memory). This setting is now similar to my other Wren 44 and the engine has not flamed out since. I have however noticed it can be reluctant to return to its correct idle speed and will sometimes hang up around 80k. I hope this is because the fuel pump is new (sticky) and needs to settle down. For info my engine is a 44 gold (the new version) with a 7.4v Wren LiPo. As mentioned I have another 44 gold (exactly the same spec) and it has been faultless just like my 54MkIII.
If the idle speed issue goes away as the pump runs in then the change to the deceleration delay has fixed my little Wren If not I will take it back to Wren for some TLC.
]
05-05-2008, 10:12 PM
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RE: Intermittant MW44 Flameouts?
I was going to fly my 44 gold last week it ran great at the park but I had a brake problem so I did not fly it. The next day I ran the 44 gold in my garage and it flamed out 4 times in a row when it reached 155000 rpms,,,,,,,,,,,,,,,the turbine also would not hold an idle. Low end was in the 60000+ range. Next day I went back to the field with it so that the other fliers could see it run and verify my claims.................it ran perfectly. I concluded that at home I was swamping the receiever with the transmitter because it was held close to the nose of the plane were the electronics were located. Now I am beginning to think it was not the radio. I also had it flame out twice on a test stand but being new to turbines I felt that I did something wrong.
Glenn
Glenn
05-05-2008, 10:17 PM
#16
RE: Intermittant MW44 Flameouts?
ORIGINAL: L Turner
Gents,
Also having flameout problems with my Green '44 just 2nd flight back from a check up by Wren (inspection, flameout problems) who set it up with a new FADEC. I noted on the ground after the 1st flight that it would not return to idle rpm properly, sitting at about 80-90k for a prolonged period, with PW about 120, taking almost 3-4 minutes to return closer to idle (PW 108), when I shut it down at 60k. I had also run it from idle up to 195 k and back several times before the first flight, to be sure it had adjusted to the new throttle travel. It exhibited normal PW at idle and max rpm prior to the next flight. The flameout (Speed low) occurred at the end of the next flight, after throttling down on final (good place to quit). The Pulse width was 120.
One question I have always had is what is the proper cell count for the '44 FADEC battery? I use a 4 cell 1100 ma Nicad, fully charged usually 5.2-5.3 V before my first flights. At idle, the PW is about 110, but full throttle only 390 or so. The old FADEC manual indicated full power PW should be somewhat higher than 6-700. Does this indicate too much voltage, such that the range of PW is very small (390-110=280), and the FADEC-solving for the proper PW to output to the fuel pump-cannot alter the pump power with enough resolution towards idle? Has anyone tried to run the Green '44 on a 3 cell nicad, as they were originally equiped years ago? Perhaps Roger or Gavin could comment on this.
I remember there was some discussion of this flameout problem on return to idle by Gaspar, a number of years ago. He suggested using a couple of T fittings and making a bypass to return some fuel fuel from the pump outlet back to the inlet side, so the fuel pump ran with slightly higher PW at idle.
Gents,
Also having flameout problems with my Green '44 just 2nd flight back from a check up by Wren (inspection, flameout problems) who set it up with a new FADEC. I noted on the ground after the 1st flight that it would not return to idle rpm properly, sitting at about 80-90k for a prolonged period, with PW about 120, taking almost 3-4 minutes to return closer to idle (PW 108), when I shut it down at 60k. I had also run it from idle up to 195 k and back several times before the first flight, to be sure it had adjusted to the new throttle travel. It exhibited normal PW at idle and max rpm prior to the next flight. The flameout (Speed low) occurred at the end of the next flight, after throttling down on final (good place to quit). The Pulse width was 120.
One question I have always had is what is the proper cell count for the '44 FADEC battery? I use a 4 cell 1100 ma Nicad, fully charged usually 5.2-5.3 V before my first flights. At idle, the PW is about 110, but full throttle only 390 or so. The old FADEC manual indicated full power PW should be somewhat higher than 6-700. Does this indicate too much voltage, such that the range of PW is very small (390-110=280), and the FADEC-solving for the proper PW to output to the fuel pump-cannot alter the pump power with enough resolution towards idle? Has anyone tried to run the Green '44 on a 3 cell nicad, as they were originally equiped years ago? Perhaps Roger or Gavin could comment on this.
I remember there was some discussion of this flameout problem on return to idle by Gaspar, a number of years ago. He suggested using a couple of T fittings and making a bypass to return some fuel fuel from the pump outlet back to the inlet side, so the fuel pump ran with slightly higher PW at idle.
Dave Rigotti
05-06-2008, 12:38 AM
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RE: Intermittant MW44 Flameouts?
Hi All
If you get a flame out from idle to full power when the engine is throttled up fairly briskly and immediatley after flame out you get a plume of white smoke this indicates a non commanded shut down most likely caused by over fueling the engine. The fix is to increase acceleration delay by maybe 5 increments.
The same goes for flameouts on decceleration incraese decceleration delay by 5 points. If the ECU indicates engine shutdown is for under speed and you get a plume of white smoke this indicates the engine is being over fueled whilst accelerating or deccelerating and causes the flame in the combustion chamber to break down. The ECU does not realise the flame has gone out until the rotor speed decays to below fault settings and so keeps pumping fuel into a now hot combustion chamber(hence the white smoke) until it stops the fuel pump because of low speed.
From my experience, when you over fuel a larger engine P120, KJ66 etc the engine will have flames out the back and usually shut down on over temp,on the smaller engines you will degrade the combustion process in the chamber so no flames.
Hope this helps
Kind Regards
Craig Dyer
If you get a flame out from idle to full power when the engine is throttled up fairly briskly and immediatley after flame out you get a plume of white smoke this indicates a non commanded shut down most likely caused by over fueling the engine. The fix is to increase acceleration delay by maybe 5 increments.
The same goes for flameouts on decceleration incraese decceleration delay by 5 points. If the ECU indicates engine shutdown is for under speed and you get a plume of white smoke this indicates the engine is being over fueled whilst accelerating or deccelerating and causes the flame in the combustion chamber to break down. The ECU does not realise the flame has gone out until the rotor speed decays to below fault settings and so keeps pumping fuel into a now hot combustion chamber(hence the white smoke) until it stops the fuel pump because of low speed.
From my experience, when you over fuel a larger engine P120, KJ66 etc the engine will have flames out the back and usually shut down on over temp,on the smaller engines you will degrade the combustion process in the chamber so no flames.
Hope this helps
Kind Regards
Craig Dyer
05-06-2008, 01:58 AM
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RE: Intermittant MW44 Flameouts?
I am experiencing the same problems as KWB with my Gold 44. It originally would (intermittently) stop when on ground and shutting the throttle, after max throttle. I phone wren who advised me to alter the deceleration delay. I increased this from 17 to 27. It seemed to cure the problem and it will not stop on the ground. In flight, however, it will still stop and has caused the loss of a model. I have now installed it in a new model (totally different fuel installation) and in its first three flights it has stopped twice. No air is evident in the fuel lines ( I run a UAT) but some times a smoke trail can be seen on shut down. The engine idles on the ground at about 60000rpm, but does surge. The exhaust cone has uneven heat markings. The only Fadec readings I have retreived have been "Stop".
Getting frustrated with this one.
John
Getting frustrated with this one.
John
05-06-2008, 02:29 AM
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RE: Intermittant MW44 Flameouts?
Hi Johnls
White smoke indicates a non commanded shut down as I described earlier. Try increasing the acceleration delay and for the surging try adjusting the stability delay.
Regards
Craig
White smoke indicates a non commanded shut down as I described earlier. Try increasing the acceleration delay and for the surging try adjusting the stability delay.
Regards
Craig
05-06-2008, 03:36 AM
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RE: Intermittant MW44 Flameouts?
ORIGINAL: Gaspar
Now that Sara don't hear (read) me, I suggest to try what I suggested in other similar threads, simply derate the pump trough a bypass, with a T fitting between the pump and the engine, and sending back to the tank or to the pump input some fuel, regulated trough a adjustable (needle) valve ....
.... just the usual warnings, this is NOT a WREN recommendation, do it at your own risk.
Gaspar
Now that Sara don't hear (read) me, I suggest to try what I suggested in other similar threads, simply derate the pump trough a bypass, with a T fitting between the pump and the engine, and sending back to the tank or to the pump input some fuel, regulated trough a adjustable (needle) valve ....
.... just the usual warnings, this is NOT a WREN recommendation, do it at your own risk.
Gaspar
There are a number of different issues here so I'm asking Mike and Gavin, the experts on the 44, to deal with this and will be back later with more information.
Sara Parish
Wren Turbines
05-06-2008, 05:55 AM
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RE: Intermittant MW44 Flameouts?
The experts have looked at this thread and say that there appear to be several different reasons for the flameouts and they need to look at each one separately. I am mailing all the customers on this thread privately with information and advice. We wish there was one solution for everything, but there isn't because flameouts can be caused by a number of things - see the discussion on another thread.
Edit: Something else which is causing confusion is the fact that some of these engines are manual start and some autostart, so they use different batteries, but people don't make it clear in their posts which version of the engines they have.
Please, if you have a problem, talk directly to Wren and don't just ask for advice on the forums. We do our best to be accessible and quick with email response. We have deliberately chosen not to have a section in the manufacturers' forum area because we don't want people searching through trying to find relevant information if they have a problem, it can do more harm than good and cause frustration all round.
Sara Parish
Wren Turbines
Edit: Something else which is causing confusion is the fact that some of these engines are manual start and some autostart, so they use different batteries, but people don't make it clear in their posts which version of the engines they have.
Please, if you have a problem, talk directly to Wren and don't just ask for advice on the forums. We do our best to be accessible and quick with email response. We have deliberately chosen not to have a section in the manufacturers' forum area because we don't want people searching through trying to find relevant information if they have a problem, it can do more harm than good and cause frustration all round.
Sara Parish
Wren Turbines
05-06-2008, 07:11 AM
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RE: Intermittant MW44 Flameouts?
Sara,
Sorry I didn't wait to post. The multiple replys in this thread certainly contain way too many apples and oranges, Greens vs Golds, different battery systems, different FADEC parameters, new vs well broken in fuel pumps, making your case for addressing the problems individually.
Honestly, had the flameout problems described, but I know it ran well for you just a few cycles ago. No parameters changed, different fuel system, and I only wondered what voltage battery supply it was tested on at Wren.
Going out to test again today, hoping to retrieve the boy's advice before I go. Will forward my different home email for any suggerstions.
L Turner
Sorry I didn't wait to post. The multiple replys in this thread certainly contain way too many apples and oranges, Greens vs Golds, different battery systems, different FADEC parameters, new vs well broken in fuel pumps, making your case for addressing the problems individually.
Honestly, had the flameout problems described, but I know it ran well for you just a few cycles ago. No parameters changed, different fuel system, and I only wondered what voltage battery supply it was tested on at Wren.
Going out to test again today, hoping to retrieve the boy's advice before I go. Will forward my different home email for any suggerstions.
L Turner
05-06-2008, 09:38 AM
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RE: Intermittant MW44 Flameouts?
ORIGINAL: WrenTurbines
Please, if you have a problem, talk directly to Wren and don't just ask for advice on the forums. We do our best to be accessible and quick with email response. We have deliberately chosen not to have a section in the manufacturers' forum area because we don't want people searching through trying to find relevant information if they have a problem, it can do more harm than good and cause frustration all round.
Sara Parish
Wren Turbines
Please, if you have a problem, talk directly to Wren and don't just ask for advice on the forums. We do our best to be accessible and quick with email response. We have deliberately chosen not to have a section in the manufacturers' forum area because we don't want people searching through trying to find relevant information if they have a problem, it can do more harm than good and cause frustration all round.
Sara Parish
Wren Turbines
Hmmmmmmmmmmmmm!!!!!!!!!!!!.