Could an agressive throttle curve program cause a flameout, coming back to idle? I have had a few low rpm shutdowns inflight after coming back to idle.
I have programmed this function to try to give a more linear throttle feel. Before it seemed all power was at 3/4 and above.
Scott Marr

Scott,
FWIW on my P80 I have jumped the throttle curve up also like you have and have never had one flameout yet. And I have done full throttle to idle chops.

I too have used exponential throttle curves. The stock curves are not to my liking either as most of the power comes on in the last bit of stick movement.

As for the low throttle shoutdowns, we have been experimenting quite a bit. We still cannot isolate any cause.

There is a fairly complex relationship of many factors that are at play here. If you noticed, the idle of the JetCAT is very stable compared to other brands. This is because JetCAT uses sophisticated software algorithms to control the pump (CAT, the parent company makes lab equipment that control rotating pumps and stirrers to parts per million accuracy)

We have developed a software fix (brief non linear derivative gain term for you engineers) that prevents the overshoot problem from occurring, even though we do not know what is causing it.
We were going to announce this later, but after a bit more testing, we can upgrade anyone's ECU with this mod for 15 bucks plus shipping. We are not encouraging this mod across the board, as whatever this is, it seems to be very isolated.

Any questions do not hesitate to ask. Most reps do not know anything about this as this announcement is about a week to a week and a half premature!!

This is great news!!
I call to set it up.
Scott

Sorry to barge in on this thread but.....

Can you guys give me an idea on what your throttle curve looks like when modified? Would like to try it but not quite sure where to bend the curve and how much

Thanks...
Todd

Try this, you have to experiment with actual values

Yea...I think I got it....

Looks like about 30 to 35% POSITIVE expo???

Thanks Matt!

Not sure about positive and negative, I think that depends on the manufacturer

Also, I do not use expo, but instead a throttle curve function, maybe it is only used in helis, anyway it is on my 9ZAPS so I use that.

Anything that will give a transfer function like the graph shows will work.

The 10X has a throttle curve also, thats how I did it.

That almost exactly how mine looks on my 10X
Scott

FYI, On an older P120, pre rev 4.0 ecu, I had a couple of flameouts on the ground when throttling back. I ended up re-teaching the ecu after I reset the 10X back to factory setings. I also made sure that the TRIM is pushed all the way up. Never saw the problem again. I sold the engine and have not heard any bad feedback about it so I am assuming it is ok.

Wow.. that's a lot steeper than what I setup on Jon Vance's P-80.. I'll have to tweak it a bit more. I hated the stock setup.. almost no power down at the bottom of the travel.

-Doug

I found the high exponential curves not to my liking on either end so I set up my P-80 with a throttle curve to give a "linear" thrust response:

Stk Cmd Thrust
%.......%........lbs
0.........0.......0.9
17.......31.......3.4
34.......51.......6.1
50.......66.......8.8
67.......79.......11.6
84.......90.......14.3
100.....100.......17.0

This is on a Stylus, I'm told you can't input a curve this way on a 10X.

BTW does anyone have a complete P-80 thrust curve, I had to curve fit this one to rough data.

PS: anybody know how to tab data in a message????

Hi there.!!

I have been experimenting with the expo throttle curve on my Futaba 8UAP radio.
I want to boost the trust on my P120 v4.0 at low end a bit more. Before this the engine ran normally good. Now I set the expo curve to +30% .If I set throttle trim full up ,the engine will not start ( single channel startup) . If I set this to less then half trim the engine starts up. Question ?? Is this normal ?? Is the expo too high??
Thanks in advance.

C Lim

Hi there

I am experimenting with the low end throttle curve on my Futaba *UAP P120 V.4. Before the engine ran fine. Now I set the throttle expo to +30% . During startup ( single channel ) full up trim the engine will not start , If I move the trim to less then half ,it will startup.

Q?? Is this normal ? expo trim to high?? Too high a expo ??

THanks in advance.


C Lim

Sounds to me like you need to re-program your ECU for your new expo settings. You exponential throttle is now not operating the way your ECU expects (ie your trim lever no longer has enough "throw" to control the ecu functions).

Also, I would recommend actually using a helicopter style (multi point) throttle curve as opposed to exponential. These exponentials normally have effect around the center of the travel, which is not what you are looking for. You need the multi point curve function. Maybe these radios have something like multipoint on throttle expo, I am not a radio expert by any means.

I posted a picture of this curve further up in this same thread.

Good luck

Hello Mr Matt

Thanks for the respond. I'll just reset every thing back to before.
I am looking at the JR10x or Fut 9CAP for the extra channel smoke system and then chuck the old 8UAP ( no throttle point curve ) out the window.

Thanks again

C Lim
Aruba

Be careful not to get too aggressive on the throttle curve. I tried to duplicat Matt's curve into my 10X for my P160. I advanced the throttle a little too fast one time and it flamed out and then belched out a lot of smoke. I cooled it down and it restarted fine.
I think I "flooded it" with too much fuel and the smoke was the excess burning off.

BTW I took the curve back out and will fly it with the stock throttle setup.

For you that have had cutoff at low throttle check to see if your throttle control will spring a little more when you pull it or that it not on the top of a tooth and will hop forward when you let go.
The speed of the throttle is controlled by the ECU, but you can force it lower. Also look at how much trim you have, you could add some more on most TX.
Darryl Usher

Matt ... seems like there are a lot of us using a throttle curve to work around the "stock" throttle response. Has Jetcat considered making the stock response more like these custom curves ?

Just a thought.

Gordon

For JR PCM 10X owners who are concerned with "chopping the throttle" you can slow the throttle servo (response) down using the Servo Speed function (code 24 I believe). Then no matter how fast you move the throttle stick the actual throttle travel will be slow and steady. I have used this feature a lot in piston powered planes and it works very well.

Len

can anybody tell me which curves they are using on a jetcat 120

Cheers

i find with my 10 X , that with a lot more pressure on the stick, this will actually cause the pot to issue a lowr/higher reading .... I have had flame outs on my p80 , and i traced this to pulling hard downd on the throttle stick (pas the programed position the ECU expected .. I resolved this my relearning the UCU functions, but this time while pulling hard down on the stick for the low throttle/up trim setting ... no more flameouts ..


Wojtek

Hi
I have had this problem on a P60 and it was fixed by John Redman giving me new settings for the ECU . This was a factory style setting and is not an open adjustment ( ie you cannot do it without expert approval as it is within the ECU basic settings unavailable to us mortals) However IT WORKS !!!

I have now done 12 hours + on the ARF Boomerang /P60 and 10 of them with the new settings. It NEVER misses a beat at any time.

Well done that man Redman and thanks again as I had at least 6 overtemp cuts and compromised the model each time so I may have not got away with the seventh !

David

Len,

Any thoughts on what speed to set it at?

Thanks,

B