Hey,

What is the best way to degauss the rpm sensor on a fadec banana hall effect board. Think mine my be a little out of line, even runs perfect till around 80K to 90K rpms then slows starts dieing then just shuts down. Anyother ideas of than the rpm sensor maybe being off, read a post in the old RAM forum where a guy had a 500 and it was doing almost the same thing so a person suggested degaussing. It idles fine at 45K and will run fine around 60K aswell.

The way you do that on a RAM is you take medium size magnet and pass it through the outside cover of the engine where the board is located. By medium size, I mean it has to be at least two inches long, but bigger is easier. Don't expect a refrigerator magnet to do the trick ( I have seem people try with one so that is why I mention it)

Turbulence

I have a magnet shaped almost exatly like the "Banana" shaped Hall effect sensor that came out of a hard drive but that might be to strong (powerful)

Does that seem to sound like what the problem is. The sensor is located right above the magnet in the compressor just on the other side of the front cover, Its also aligned with the magnet and not offset. Does that seem to sound like the problem. Its on a FADEC ECU

From the Simjet website. [link=http://www.simjet.com/service.htm]http://www.simjet.com/service.htm[/link]

RPM sensor pick up, some customers have informs us the they in on out of 5 or more starts have aborted starts just after propane ignition or in most cases under 25000 rpm , we found that is due to a week or distorted pickup, this can easily be fixed by neutralizing the pickup with a magnet, remove the front cover with the starter on by taking the 4 pc 2 mm screws of , then take the 2 pc 3mm of the sensor board flip it over to one side and slide a magnet as close as possible over the pickup form side to side a minimum of 6 times like on the picture. this procedure will cure the problem and the output signal will raise 4 times ( this do not have to be repeated later )

KAOS,

That helps alot, still not sure how strong of a magnet to use, im afraid the only thing I have is to strong (hard drive magnet) and to weak, (round frigerator magnet) Don't really want to take the cover off just because o fthe gobs of wires but I guess I can.

hi Skymac

i guess you are referring about the JJ1200 engine since i saw your post here:

quote:"We have a few cycles on the engine now. FULL STOCK as recieved from Jet Joe. We are working very close with Joe to fix anything that may be wrong in the short term and long term. We do plan to run it at the max rpm but not for a few runs. Anything that is fixed or changed will be annoucned once we have everything done but untill then im not going that deep. As you can see we are running the Fadec Semi-Auto Unit with the Stock Jet Joe pump and Stock Jet Joe Hand Starter."

since you are closely working woth JJ on this cant he answer this?

well let me tell you about the rpm pickup it is ........ perfect!
still like i said the JJ engine and i am sure you are referring to this engine , only you try to find out silently why the JJ wont go over 80000
so we would be all wrong right? look here: "http://www.rcgroups.com/forums/showthread.php?t=263834&page=36&pp=15"
i allready told this in another forum well known
this engine WONT run over 80000 rpm,s anyway
it is a design fault on jj,s behalf if you read all the posts you can almost figure out in why it does not go over 80000 rpm,s
the fadec is not at fault here , i use many fadecs and the only time it did not work was when the compressor digested the rpm pick up cable ;-)
anyway all the answers are there
wait let me copy and paste it for you:

"like is said i was in contact with thomas there is no use to run it
it is not going anywhere.
eveyone seems to get one of these help yourself
tom tryed to help as much as possible and urged JJ to wait with sales and first straiten out the problems , to make a safe engine
we know it is not going to run as is
it needs lots of changes to have it run
and if you dont have the tools like thomas has forget it
you can run maybe it to idle or slightly more but after this
flames will come out and engine will sease to a stop
here are a few things noticed by now:

combustion chamber is mounted wrong
copy of the wren combustion chamber is wrong
sticks are mounted wrongly
sticks will burn off after about 1 hour of run
all needles need replacing
the lubrication needle is very bad made
pre load is needed, new tunnel
space need to be less for compressor clearance
balancing needs to be re-done
turbine wheel needs to be straitened out so it wont "wobble" anymore
turbine wheel needs to be drilled correctly
front bearing needs to be replaced with a grw one
exhaust needs to be redisigned
all "festo"parts need to be replaced
starter motor burns out needs to be replaced
magnet in spinner is mounted wrongly
fuel pump leaks and does not give any pressure
fuel pump has no noice reduction needs to be filtered

these are just a few things i noticed when tom and me inspected the engine where mine was new and toms engine has runned for about 20 minutes all in all
so as soon jj got this straitened out i think the engine will get above 80000 rpm,s we hope
we dont know what the engine wil do when it is going to produce some actual thrust

i see you made a nice test stand for now you can use 1mm plywood

regards

Sandor

No need to degauss the sensor on the fadec pickup, it does calibrate itself. If you have bad RPM reading over 80K then probabilly the magnet on the spinner is weak. In what engine you use the fadec? have ben run OK until the problem developped or is a new engine? If new, then contact the engine manufacturer for spinner nut replacement.

Regards,

Gaspar

Gaspar,
I believe Skymac is working on the JJ

Todd

Hey,

Just got back from our local field and got to see Skymacs Jet Joe run.
Although they were getting all the settings fine tuned for idle and midrange
it was still super impressive. Most of the running was done at night and it
looked to be burning very evenly in the back. Just wanted to step in here
and say that they are working very hard to get this product to be viable in
the future, so far its looking good but time will tell.

Thanks,

Joe