Jets Munt Merlin 140 -- what am I doing wrong?
 

So I tried to run a Jets Munt 140 today for the first time on Diesel. The previous owner ran it on Jet A fine, even at our altitude here in Denver....

The first run up I advanced the throttle after it was warmed up and it just quit and blew white smoke. After cool down the next run up I advanced the throttle VERY slowly and it continued to run so I tried a taxi test because I needed to check the brakes on the Bandit. Ran fine to the end of the runway where I slowly advanced the throttle again and it abruptly died.

I had emailed Jest Munt and was told it would do fine on diesel and no changes to the ECU would be needed.

I don't have an easy way to get Jet A to see if it will do better so I wanted to see if anyone knew if it could be something different.

Thanks!

As far as you know it could be doing the same thing on Jet-A and it could have nothing to do with diesel at all. Perhaps there is either something wrong with your thermocouple or air in the system, does the ECU give you any hints to why it shut down?

Double post, sorry.

The ECU did not give any hints. I was afraid that it might not just be the diesel....

What kind of UAT are you running? Is it brand new?

Thomas

UAT is a BVM unit and it is not new.

Brand new BVM and Hanson UATs often show this symptom because it takes a while for all air bubbles to disappear from the UAT. The bag filter element seems to release these air bubbles when you taxi or accelerate the plane for the first few times. I also have several JetsMunt turbines that run flawlessly and don't show any bad habits on Diesel.

Otherwise I also do not have any suggestions, except to contact Gaspar at JetsMunt to ask for his ideas. You will get an answer very quickly.

Thomas

Thank you, I will contact him.

When running diesel it is recommended to run the acell decal on normal or slow. with altitude I would say slow

Try to accelerate the engine from idle to full point to point, allowing the engine to stabilize between points.Then, decelerate to idle point to point in the same way. Make this process twice. ( With this procedure the fadec learn the new situation. You don´t have to repeat this in the future, unless you change the pump, installation, etc ).After this, the engine should work fine. If not, increase a little the acceleration delay ( Run menú)

Jesse2357, is correct... the previous owner probably set the accel and deceleration at " very fast". This option is great running Jets A and about sea level (STP, Standard Temp & Pressure) .

I run dieael on my JM's and they all run fine but I have the rate at "fast"... Being in Denver setting the rate at " Normal" is a good idea...

PS... Bandit flies so well with JM140...:)

Sheldon I sent you a text George

I have 2 140s, and have had this same issue on one. First, I run on kero, not diesel - this is pump kero and is filtered. On the turbine with the same issue, abruptly dying at 55 - 65 rpms, I went in and relearned RC and set both the acceleration and deceleration settings from fast to normal. After this change, the turbine ran with no issues. You may want to try that and see if it helps.
One other thing to note, the outing when the problem started, the weather was hot and humid, where previously (with no issues) the weather was much cooler.

Robert

Thanks all! I will try these things and see if it helps.

This is unbelievable to me, but I sent this message last night on a Saturday and got a response from Gaspar. Wow.

"Hello Sheldon,

If using diesel and at altitude and or high temperature, the acceleration and deceleration should be set to slow or very slow, diesel burns slower than kero. Also you should check that in your installation the engine don’t swallow its own hot exhaust."

One other thing that will help besides slowing down the acceleration curve, is to turn up the engine idle a bit if you can do it without the model wanting to taxi off. If it gets that high the residual thrust will make it a pain to land.

Thanks Zeeb, if the above does not work that will be my next step now...

I had exactly the same issue with my 140XBL. Perfect until recently and then continual flameouts. After sending Gaspar ECU downloaded and trying various things like slow accel/ decel rates and running it on a test stand he came to the conclusion that it's stall margin was lower than normal and the hot summer conditions ( high density altitude and humidity) caused it to flame out. It was also probably producing more thrust than normal, but sacrificing stability for the extra trust.

My engine is now on its way back to Spain to be adjusted to increase its stability.

My second 140XBL runs perfectly.

Great service by Gaspar and the entire Xicoy and Jets Munt teams.

Paul

Well I got it to run fine, just went with the "very slow" on both accel and decel and it was doing fine. When it cools down some here I will try "slow" but for now it is running and not flaming out.

Thanks again everyone for the help.

No further advice from me, except to endorse what L A jet says.

A Bandit / M140 combo is a superb combo. I run mine limited below max rpm, (cant recall exact ) and it is still scary quick. I use the standard BVM tank UAT system and it all works fine..

Roger

Thanks, I actually have on of LA Jet's old Bandits and I think it is among the best in the country!

You'll find that setting really hammers your throttle response but not much you can do about it. If it were me, I'd add a couple thousand RPM to the idle and try a faster spool up. Then in the fall you can change things or if you go down to Sea Level.

We had to do that on your Futura over here in the Summer.... ;)

Try to increase the throttle response after some flights, ( or after to make to the Fadec the learning process of accelerate and decelerate step by step). Hopefully it will work.

Thanks Zeeb. I am going to fly it this way and then experiment to see if "Slow" will work, and if not then I will add some to the idle. It already is close to rolling around at 35,000 because it is pretty light.

Once you get comfortable with Bandit w/140..... you should try a Super Bandit w/200..... Super Bandit is made for speed...

Enjoy your Bandit... best sports jet made so far...


PS.. I have tried Ultra Flash w/200... close but still Super Bandit hands down