LOL - I try to help clarify what I think you guys are saying, and instead I muddy the waters. Par for the course, I guess.

If it's not too much bother, or giving away IP, how do you determine that a PPM signal is corrupted ?

Gordon

Yes I think I have confused things here!

First let me make sure everyone understands what I am talking about.....

I am talking about a system that can shutdown the turbine under a PCM FAILSAFE event, with a user programmable delay. The JetCat system will also shutdown on the complete loss of signal (or garbling of the signal) with a PPM system as well, uing the same user programmable timing.

That was my mistake, as I do not run PPM with turbines, nor do I know anyone who does, but to each his own, our system works with PPM as well.

I think the SIMJET system will shutdown with a loss of the PPM signal, but I am not sure what it does under PCM...just as Gordon indicated I think it is semantic.

Sorry if I have further confused this, but I think it is important in the new proposed rules to have shutdowns to decrease the chance of fires.

Also I know most people use PCM. I also know that many turbine fliers that use PCM do not want an instant shutdown.

I know JetCat will let (PCM and PPM) users, that do not want instant shutdown on a failsafe event, to achieve their goals. Not sure of the other manufacturers, I am sure they will speak up here.

Okay, s p e a k i n g v e r y s l o w l y s o I d o n o t m a k e t h e c o n f u s i o n w o r s e . . . .

The built-in failsafe in the SimJet ECU will trigger after a 0.5 second loss of signal or sufficintly garbled signal. Like Matt and most others in North America I've never flown turbine powered aircraft on PPM, however I was trying to ensure that all the relevant infomation was presented. (Incidentally, I understand PPM is the preferred system to fly with in Europe. If any of our European friends have any opinion to voice on this please PM me as I'd like to know...)

On the subject of PCM, assuming the end user has set their radio system to command shut-down on entry into fail-safe, the SimJet ECU will give you 0.5 seconds to recover from fail-safe after which it will shut you down. While this time period is not adjustable by the end user, if anyone REALLY wants it altered I have the power to do so.

Argh- it took out all my extra spaces!

The RAM/FTE remote start ECU is the same, only the time period is 1.0 second. The manufacturer is looking into a software upgrade to allow the user to select a time.

Steven

Currently, I have my turbine go to idle and the gear down when the RX goes into fail safe. (Which I have never experienced) I don't remember how many second delay I have programed into my JR radio. To be compliant with the new rules I'm going to see if I can program the radio for shut down, negating the need for an added mechanical or electrical device. If it works then this would be good news for those that have ECU's like mine. (No fail safe shut down)

Kevin

Hey Matt, you know me! The MPX Profi 4000 12 channel is PPM with IPD receiver fail safe. You know, the one in the pizza box!!!

How do you other manufacturers handle a normal shutdown?

I mean if you add this "failsafe" delay, won't that delay the time for an emergency shutdown? Imean if you use the radio failsafe, the ECU cannot tell the difference from a normal shutdown, right?

With the JetCat system, the delay ONLY occurs on a PCM failsafe, or a garbled PPM signal. Manual (emergency) shutdown is still instantaneous. Important safety item IMHO.

Does anyone know what the TRC intended? Are all shutdown (including manual emergency shutdowns) to have a delay?

PS Mark how could I forget about you!!

Matt,

I can't speak for AMT but I'll describe what I hope will happen with my experimentation with my AMT Mercury.....

Program in the radio a failsafe that is tied to the emergency shutdown switch. Failsafe over-ride to shut down the turbine after a predetermined time will only occur in the event of a failsafe. If no failsafe condition exists, the switch will work normally. (No delay.) This makes sense to me as all of the other channels work normally during non-failsafe periods and are over-ridden only when a failsafe conditon occurs and the failsafe is programed. Does this make sense to you???

Kevin

Hi Kevin,

Yep, Gordon hit it on the head, we definitely have a semantics problem here!

We are discussing 2 distinct scenarios:

1.) A normal failsafe gets generated by the receiver. In certain radios (JR 10X?), a delay can be programmed in, wherein the radio goes from "hold" to whatever the failsafe preset positions are. This is the delay you are describing I assume? This failsafe occurs, after the delay, the receiver commands the ECU to shutdown in the same matter as pulling the throttle back...the ecu cannot distinguish this from a normal shutdown whatsoever. I agree in this case, your radio would distinguish between a commanded (emergency) shutdown and a failsafe (delayed) shutdown.....sounds good to me. I fly Futaba and we do not have this feature, at least not in the 9ZAPS unless I missed it.


2.) Again, a normal receiver failsafe occurs, but in this case, it is interpreted by the ECU to be a failsafe event, completely independant of the normal shutdown of the turbine. In this case the delay is introduced by the ECU. This could cover the cases of radios that do not have the failsafe dely feature.



Clear as mud, right?

Matt:

No programmable delay in the 10X....not sure, but I think there was in the 10SXII.....that's the beauty of the JetCat ECU, as you can now program the delay using the 75%/100% travel on the throttle, so as to simulate a normal shutdown pull back of throttle and trim when it stops getting a valid data train from the RX.....I keep mine at the default of 3 seconds....since any failsafe longer than that is more than likely to be permanent, and the plane is going in.....

Tom

Matt,

Yeah, I have the JR PCM 10 SX-II. Another reason why friends shouldn't let friends fly Futaba!!!

Tom,

I agree, the JetCat ECU is the benchmark that all others are judged!!! I like my little Mercury but my P-120 rules...I just didn't say "rules", did I??? Geeeze, I've been listening to my daughter too much....

Kevin

Futaba PCM may not have a delay setting, but there is a delay.

At loss of signal, the receiver will hold all outputs at the last received setting for one second. After the one second hold period, the servo channels that have been setup with failsafe values go to those values.

You can turn the transmitter off and observe the one second delay before the receiver sets the servos to their failsafe positions.

Futaba transmitters have a boot up time of a second or two, so you can't verify that the receiver didn't go to failsafe if the loss of signal was less than a second by simply turning the transmitter off then on within one second. You could pull the module and replace it quickly, or generate interference from a second transmitter.

Kevin Green,

Lets try this another way since you may have not understood my first post. Lets say your 3 position switch for AMT run mode is channel 8, simply go into code#77 and set channel 8 for Fail Safe verus Hold, Then set the switch for channel 8 in the Emergency off position prior to hitting memory. Thus when it goes into hold the radio will shut down the turbine.

What objective am I misunderstanding that you are trying to achieve that this does not address?

Tom,
Perhaps Jr moved it into the factory setup screens, Ill get my cheat sheet tommorow and check around in there.

C/F,

I understand how to do it I just haven't had time to sit down and play a little as the weekends are reserved for family time . I was just going over it "out loud" here on RCU from memory and wanting to discuss it here. Besides, it got COLD here!!! The high today was only 40 degrees!!![:'(] Yesterday it was in the lower 70's...I won't get outside and play with the radio until it gets a little warmer. Thanks for wanting to help me out though!!![8D]

Kevin

Re-read the proposed regs. --- the delay required is 2 seconds is it not in the ECU/turbine?
And check your JR Radio out ----- Transmitting to an S mode receiver the 10X's failsafe is "INSTANTANEOUS NO TIME Delay" -- allowed the biggest problem I have with the JR 10X. JR is one of the main reasons the ECU's were reprogrammed for fail-safe time delay. 10X transmitters do allow failsafe delay up to 1 sec max. if you are transmitting to the older 512 bit PCM receivers! Screwy huh-----
Lee

WOW I am more confused than ever, but if the 10X does not have the delay, I know the 9ZAP does not have it, it will need to be in the ECU at least for those 2 radios.

And I will say again, I hope that if delays are added to ECUs, it is for !FAILSAFE ONLY! and not just some delay to the normal shutdown time. I think that would be a gianst step backwards with regard to fire safety, the REAL safety issue with turbines!

I think that the "added delay" issue will have no more of a right answer than the "shut down or idle on failsafe" question- Ask ten different people, and you'll get 10 different answers.

SimJet's ECU introduces a 0.5 second delay in all cases. So in the case of loss of radio contact with my 9ZAPS, there's a 1 sec delay from the Rx entering hold to commanding shutdown, plus the 0.5 seconds delay for the ECU to accept the shutdown command. (Total 1.5 sec for radio LOC) In the case of a commanded (or emergency shutdown) it's the time it takes for me to get to the kill switch plus 0.5 seconds.

Is that a safety hazard? I would argue not- I still had time to get things shut down after my Facet mid-air'd at Superman.

Go check your manual, page 56. Transition to failsafe is NOT instantaneous, it is fixed at 1/4 second. Now granted, 1/4 second may not seem particularly long, but the RX does still get quite a few frames during that 1/4 second, and EVERY ONE OF THEM has to be corrupt in order for the failsafe to kick in - because as soon as a single valid frame is recieved, a new datum is recorded for the point from which another 1/4 sec worth of corrupt frames has to exist before failsafe will be initiated. That is quite a lot different than having the failsafe kick in on just a single corrupted frame, which is what your "instantaneous, no time delay" claim implies.

Even with my old ZPCM systems, I used 1/4 sec anway, and have never once had a failsafe triggered in the 15 years or so that I have been flying PCM.

Gordon

[Edit: typo]

Well then I hope we can agree to disagree. To me, if there is ANY window to shutdown the turbine before a crash, it should be used and not delayed no matter what.

Since it is a bit confusing about what the different manufacturers do, I will spell it out for the JetCat system:

1.) On an PILTO SELECTED EMERGENCY SHUTDOWN, there is NO DELAY. The turbine is shutdown INSTANTLY (within the normal milliseconds of delay of a typical radio system has for any command)

2.) On a "RADIO FAILSAFE SHUTDOWN" the turbine shutdown delay can be programmed from .1 seconds to 3 seconds (actually more) but basically programmed to anything you want. This delay is completely independant of the delay associated with the radio mentioned in number 1.)

It is my intention to spell this out completely to the TRC and the AMA, and let them make the decisions based on accurate data.

I'm gonna show a bit of ignorance here, but do all ECUs have failsafe programing built in? I mean this is no big deal for the Jetcats and other newer engines, but has anyone considered all the older, but still very flight worthy turbines that don't have this feature?

The way I read this, if your ECU can't be programmed, your grounded on 1/1/05. Hopefully I'm reading this wrong.

Matt- I respect your position to disagree without beginning a brand war.

If you have any solid data that supports the idea that a short delay time in shutting down poses a significant hazard, I'd like to hear it. (Other than "It's just common sense"- Since the time it takes from commanding a shutdown to "fire out" will in many cases be largely determined by the reaction time of the pilot involved, and to some extent wether or not he even has the presence of mind to recognise the developping situation, splitting hairs over a 0.5 second ECU delay based on gut feelings of "how things should be" is not time well spent, IMHO.)

I fully recongnise the fact that the scenario can and does exist that a short ECU delay in shutting down could cause a running turbine to impact the ground. But you must also recognise that by the same logic, in a similar scenario, any delay in shutting down due to loss of radio contact, even 0.1 seconds, is equally dangerous. Before anyone gets all up in arms and accuses me of trying to knock the most popular system in North America, I'm not. What I'm trying to point out is that there is no right answer for even most situations, let alone every situation. (The fact that there are folks who openly state that they will only set their throttle failsafe to IDLE, defeating any manufaturers safeguard, is proof enough of this point.)

Ultimately, I like to think of myself as a responsible turbine flyer. If there is a compelling reason, supported by fact, to influence a change to SimJet's or anyone else's safety system, I'm all ears to it.

In my humble opinion......

By DEFINITION, an emergency shutdown system that introduces a delay AFTER THE PILOT HAS RECOGNIZED AN EMERGENCY and COMMANDED A SHUTDOWN, will in and of itself INCREASE the RISK OF FIRE...there just is no other way of analyzing it as far as I can understand. One may argue that the increased risk of fire is slight, but that does not counter the fact that the CHANCE OF FIRE IS INCREASED.

As for comparing the delays associated with this scenario (ie the inevitable human reaction time delays associated with a PILOT COMMANDED EMERGENCY SHUTDOWN) to the delays imposed on a DELAYED FAILSAFE SHUTDOWN......I believe the point is valid...

Introducing a delay at failsafe does indeed INCREASE the chance that a model will hit the ground with the turbine running. The problem is, almost no one I know was setting the failsafe to instantly shut the motor down on a failsafe event, as the normal TX/RX system could not FILTER OUT THE SHORT, LOST FRAMES inherent with a modern PCM system.

If one advocates a rule that all turbines must shut down the INSTANT that there is a (recoverable) failsafe event, then so be it. I think most people (TRC/JPO/members in general) do not want this.

On the other hand, to burden these same users with a delay in their PILOT COMMANDED EMERGENCY SHUTDOWN, with an attendant INCREASE IN THE RISK OF FIRE is in my opinion not a good trade off for the overall safety in the hobby.

Do you guys realize that this is the type of techno-babble that the AMA will use to delay or further change the rules against us? Just my humble opinion, we are displaying our dirty laundry for all to see.

Thanks Dave, forum moderator.