DX7 & throttle hold issues??

[chugga-bug]

Has anybody had an issue with THR hold not working in idle 1/2??
Happened to me on Sunday.
I was flying my Knight for the first time, just hovering about running in a new engine, and found that on a couple of occasions the throttle hold didn't work! Gave me a bit of a shock for a moment but when I switched back to Norm mode it worked fine. Happened a few times but not all the time
I can't recreate the problem on the bench so I'm wondering if it's got something to do with the CSM RL20 I'm using??
Any ideas please??

[robgt]

No problems with mine...
Sounds odd!

Cheers,
Rob

[moyesboy]

I'm running a CSM revlock 20 and throttle hold has worked for me so far no issues.

[simon_h]

I can't recreate the problem on the bench so I'm wondering if it's got something to do with the CSM RL20 I'm using??

Possibly.... You DID set up the RL20 exactly as per the CSM guide (including the often buggered up Idle throttle and full throttle calibration) didn't you?
I only ask 'cos the parameters the Rl20 runs to is that it becomes active if
1) The throttle is raised 25% above idle
2) The sensor is OK
3) The engine RPM are above 75% of the target gov rpm.

It will disengage if
1) The throttle is brought down 15% above idle
2) The RPM drop below 50% of the target rpm
3) The sensor signal is lost
4) The throttle signal from the RX is lost (fail safe).

Idle is bold cos if you didn't set the idle throttle position correctly or your throttle hold setting on your TX is more than 15% higher than the idle setting that the RL20 has been told is idle then it will continue to govern the engine rpm.

Edit: The throttle position you tell the RL20 is idle is the combination of throttle stick and throttle trim that you use to run your engine at idle. Your throttle hold setting must be below the calibrated idle position plus 15% or the throttle hold switch will not work while the governor is active. And this would also explain why it all works on the bench as well. Your governor is not actually active on the bench is it?

Cheers,
Simon

[moyesboy]

As the throttle is increased then the red "armed" light comes on does it not? Certainly one of the LEDs goes off when the throttle approaches idle.
You have to check that when you hit throttle hold that that light is off.
Of course it will be off in normal mode with the stick down, otherwise you would have had a nasty 2000rpm startup situation (Ive been there, hanging on tight and tugging on the fuel line!).

I suspect all you need to do is wind the throttle hold position down a little, and that it is a bit near the 15% point meaning it is on the edge of arming the governor and that is how it failed.

[simon_h]

Ideally hitting throttle hold should disable the governor anyway. But I suspect it isn't set up that way. Here's how to tell on the bench.

The guff below assumes that the RL20 is disabled in Normal flight mode and enabled in idle up 1 and 2.

Swich on your TX (in normal mode) and the heli. The sensor light should be flashing. Press the set button to bypass the sensor check.

In normal mode - You should have mode A or B light flashing and with the throttle at idle the armed light should be off and your selected RPM range light should be lit. Move the throttle up and the RPM range lights should go out and the armed light should be lit.
In Idle 1 and 2 the binary code for the selected rpm setting should be on. Plus armed - plus Mode A or B as set by the mix.
While still in Idle 1 or 2 hit the Throttle hold switch. Ideally you should see the armed light go out and mode A or B start flashing like normal mode with the throttle at idle.

If the A or B mode light doesn't start flashing then your Govenor mix doesn't disable the governor when Throttle Hold is hit. Really you should set up your govenor mix so it does, but it isn't totally necessary - just desired.

If the A or B mode light is still lit and not flashing and the armed light is still lit then your throttle hold position is not low enough to disable the governor. Either reduce your throttle hold position so that the armed light goes out, making sure that the engine is still running or if that is not possible then you will have to recalibrate the RL20 throttle idle and throttle high positions and reprogram the RPM ranges as well.

Further bedtime reading....

There is a thread on RunRyder here BUT read it all before chosing any one way of doing things.

There is more info here at raptortechnique as well.

Hope this helps.
Simon

[chugga-bug]

Cheers guys I think you've cracked it
Just checked my set up and after I'd adjusted idle with the ATV's my idle position was only 82%, plus I was messing about with different T/Hold positions at the weekend. I just tried adjusting T/hold and the low ATV and hay presto! the Revlock Didn't disengage .

Now reset everything so that I've got 98% at full throttle, and 102% at low. Hopefully this should solve the problem.

Thought for a moment I had a dodgy TX....Phew!!

[simon_h]

Glad you got it all worked out.

Simon
Just back in from his first "unplanned" autorotation after it went very quiet all of a sudden...Missed the fence and it wasn't pretty, but no damage.... Phew.

[jamiem]

Glad you got it all worked out.

Simon
Just back in from his first "unplanned" autorotation after it went very quiet all of a sudden...Missed the fence and it wasn't pretty, but no damage.... Phew.

now you know you can do them and that they arent as scary as they look, you can go and do some more and perfect them!

Jamie