So I'm at a friends house tonight to run a Simjet 1200AES on a test stand.
This one is about 2 years old with about 20 runs on it.

First off I gotta say I don't like the ECU. It seems really big. Plus maybe Im just not familiar with it but I can't find any way to prime the fuel pump or to motor the engine with the starter?

First start attempt, nada nothing.
Problem traced to glow plug and fixed.

Second start attempt, we get propane ignition but no fuel pumping.
Checked fuel pump, all ok.
Tried again, same thing.

Problem traced to kinked fuel line under the cowl.

4th attempt, lights off on propane, and begins the ramp.
Everything going good and slowly spooling when I notice we are getting a small plume of fire that is gradually increasing.
Pretty soon the plume is getting very large and the tailcone begins to glow red.
I abort the the start and close the fuel valve but now I have a huge fire in the tailcone.
This is when the option to motor the engine would have come in handy.
Finally though the cool down sequence began and blew the fire out before I could grab the extinguisher.

After cool down we made a 5th attempt that ended the same way.

Anyone have any ideas?
There is no way I'm putting this engine in an airframe until I figure this out.

Im inclined to think it may have something to do with the starter motor dragging and not letting the engine spool fast enough?
Just speculating.

No offense to Simjet but man I really would like to dump the electronics and set it up with something like my FTE ECU and start box. Much more compact and user friendly, is this doable?

It almost sounds like the speed isn't high enough during the ramping of the fuel and it's pumping out too much fuel during the ramping cycle.

Cheers,

so probably the starter motor O-ring?

I couldn't tell by reading your first post but is the motor primed, fuel in the line to the cowl when the sequence is started or is it having to pump from the pump to the engine during the start sequence? Is it aborting the start on its self or are you doing it? If you are stopping it, try letting it run thru itself if you are on a test stand.

no the motor was not primed, couldnt find how to run the pump on it's own.
I aborted the start when the tailcone began glowing.
By the next attempt it was primed.

Actually I think we found the problem. When I put my finger in the front to spin the blades, it will not spin freely. It appears that the cup on the starter is not disengaging from the nut. This would make since about the motor not spooling fast enough.

ok after a bit of adjustment the cup now snaps forward and spins the engine and releases letting it spin free.
Im almost certain this was the problem. I will give it another go tomorrow, fingers crossed.

Ronnie, the tailcone glows all the time, you just don't see it in the day time. Were you running it in low light? Every engine I've run at night gets a red glow in about the midsection of the tail cone. It's made me scratch my head too, just watch your temps, that's where the info is.

no this was at like 5pm, plenty of sun.
It was very, very red, plus the large fire was kinda freaking me out as well

Just be glad that it is not a Funsonic!

Ronnie, you are correct, there is no fuel prime on the SimJet (maybe that will change in the future). On a new install, (lines empty) I usually initiate a start sequence and let the pump start moving fuel towards the engine. I will then stop the start up before the fuel reaches the engine. I will then initiate another start-up and away she goes.

My understanding is, the line has no fuel and as the ECU is ramping it is not seeing an increase so it increases the ramp slightly and in some cases by the time the fuel reaches the engine, it is a little too much to handle and will give some flames. I have done starts without the above procedure, but I prefer doing it the way I stated.

Not sure what ECU you have. Do you know if it is the lastest? If it is 2 years old it should be fine. One way to know is, that if your's is (IR) capable, then it is fine.

Sounds like you found your culprit though, good luck.

George

Yes this ECU has the IR.
It's really large and heavy compared to other ecu's

It was common on my simjet to have to pull the bendex off the compressor nut or it'd hang and the RPM's would not go high enough cause of the drag to get a good start. If I pulled on it, it'd pop off and start on up.

Sean

I have owned a 1200AES and the starter O-ring can be a PITA. It sounds like yours may be holding on too long or not getting the engine up to speed. The ECU unit does not feature a prime as already been stated. I usually made sure there was fuel in the line as close as possible to the engine. WIth a full battery cahrge, a good O-ring, plenty of gas, and a good glow plug you should get a failry quick ignition and ramp up with this engine. My tailcone always glowed if the start up was even a little wet, but as soon as the engine ramps up it, it would stabilize and would be OK.
TOmmy

I remember somebody lost his ES due to the pump not stoping in a
flame out. The plane just burnt! He said not to use SimJet again!
There was a thread about this,
I just couldn't find it.

If he had been using a shut-off valve this would not have happened. Simjet engines are fine and have a good reputation. In my opinion they all have their little "quirks" and you have to learn this little things. It is part of the learning experience.
TOmmy

I dont like the old ecu`s too much either.....but I guess that is a personal preffrence

Dont you guys have the option to buy the Gaspar Fadec with the Simjet turbines ?

Heres my simjet 3000 with Gaspar ECU.

Yes, you can the SimJet with the Fadec if you prefer.

Problem solved. It was the starter motor not disengaging.
The motor fired right up with no flames, twice in a row and ran like a champ.

What's the top RPM on this engine?
I'm showing 154,000 wide open and 52,000 at idle.

I reallly like the FADEC you can adjust everything and you have control over your affairs. Much like the old air start days. The inability to SPOOL a starter motor is a concern for me. That was my big setback with my simjet. It caught on fire once and it was at least 2 seconds before the starter figured out it needed to run.

I personally loved air start just for this reason but some ecus have the ability to run the starter and thus accomplish the same effect.

I have an idea for some of the ecus that do not have the option. I know on a semi-auto ecu it will work and i dont see why not on a full auto. Just divert your starter wires to a Rocker switch mounted in the plane and a battery. YOU contol the starter moter then at anytime you desire. Russ

ok, i thought id jump in on this one, now who in there right mind thinks its acceptable to have to stick your fingers near the bendix on ramp-up to keep it from sticking, boy they were pumping advertising and big thrust numbers. im glad i didnt buy one of those simj__k's, and no prime feature, no starter motor run feature, no pump shutdown on flameout? i thought this was 2005, is there still a crank handle on the front to start this thing. and for what its worth my p-80 before i replaced the starter on it, the bendix was sticking, and never were there any more flames than usually expected. im no software enginner but i suspect they have an algorithym or table that the ecu compares normal ramp-values with and takes action accordingly. unless an operator induced error occurs or some sort of mechanical failure occurs you just dont see flames of that magnitude from a jetcat. it wouldnt be safe practice, but i would not hesitate to start mine without an extinquisher nearby. see there is more to jetcat than a name. NUFF SAID!

Who said anything about sticking your fingers near the inlet to disengage the Bendix? The SImjet manual instructs you that the O-ring on the startermotor should be replaced or turned over after 10-12 starts. You can also tell when the O-ring starts to wear if you will listen to the start-up. There will be a squeak or even a small whelp casue by the O-ring failing to release from the shaft end.
I know alot of people who run the newer Simjets and they are a very sound and well running, as well as dependable engine.
TOmmy

The starter motor and o-ring problem on the Simjet, is that also true for the Jetcats? I don't think I heard anyone having to flip the o-ring after 10 to 12 starts on a Jetcat. Am I missing something?

thanks,

JR Gautreaux

JR, that one guy tech jet is being a moron, just because some people fly jetcat and there appears to be no problems with them to some, they might not know the whole truth. In fact, I know for sure he doesn't.

I'm not saying sticking your hand in there and pulling is NORMAL. I'm saying it's common enough seen that when it happened to me for the first time, I instinctively knew what to do. Luckily, my engine was on a ROO, so had easy access. Obviously wouldn't want to put an engine having start problems inside an airplane. (Primarily the reason I switched to Jetcat and Merlins on ducted installs).

All I can say to you Tech Jet, is that I hope I never make anyone feel inferiour to me if they don't fly what I fly. I find your post offensive to everyone who doesn't fly Jetcat. But I figure as long as your post is your opinion, no reason why I shouldn't post mine.

Sean

Here, Here!!

im usually a mild-mannered person, who doesn't have a big ego like YOU! flying model jets is a hobby or an interest in the technology and the aspect of flight for me, unlike YOU who thinks its a status symbol in your life. id say ive made a pretty darn good consortive assumption along with a persons opinion i value quite highly. somebody who has been with lockheed martin for 37 years as a quality procurement manager, in saying that jetcat is the smartest ecu on the market. now as far as the moron comment is concerned, ill brush that right of my shoulder, because the government sees to it that the information i based my purchase on is quite higher than yours. hows that for a blow to your ego! and your right in saying i dont know all the circumstances of jetcat related problems, because i dont attend alot of jet events like a miramar born topgun pilot like youself. see theres that ego again, im nobody because i havent attended every jet event in the past years. personaly i dont care what you have flown, currently fly, or will fly in the future. and lastly i never made a personal attack on you in my post, unlike you did to me in your post. i hope you clear up your insecurity issues with youself, as far as i go rock-solid.