[NSRCA-discussion] RX choices long club testing results

[Fred Huber]

If its published with the contest as an added rule that throttle failsafe 
set for idle is required....
Or if it is added as a rules change to the Pattern rules...
Or if the AMA adds it to the Safety Code (which they won't)

Then you can require the failsafe setting test.

Otherwise, you can't require the failsafe test at a contest.

Any individual club could add the failsafe rule to thier field rules.... but 
that would probably not go over well, since the majority won't have the 
failsafes.

*********

If you have failsafes... its a good practice to set it for low idle or 
engine kill... but its currently not practicle to make it a requirement 
simply because too many people don't have them.

FHH

----- Original Message ----- 
From: "Keith Black" <tkeithb at comcast.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Friday, September 15, 2006 9:49 AM
Subject: Re: [NSRCA-discussion] RX choices long club testing results


> Wayne,
>
> This is a great report and IMO should be turned into a K-Factor article.
> Are you listening Mike? ;-)
>
> I fully agree with the practice of having a Safety Office at local clubs 
> and
> contests asking pilots to turn off their radios to make sure the f/s is 
> set
> to low idle. It seems that not a year goes by where I hear about some 
> awful
> accident where a plane takes off due to f/s not being programmed and 
> people
> are endangered, hurt or in some cases killed. I just don't get why people,
> especially with large planes, won't go to PCM (or FM with signal 
> processing
> and f/s). Now with the cheaper RX's there is no financial excuse, I guess
> it's simply an education issue.
>
> Wayne, thanks for your report.
>
> Keith Black
>
> ----- Original Message ----- 
> From: "Wayne" <Whinkle1024 at msn.com>
> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> Sent: Thursday, September 14, 2006 3:30 PM
> Subject: Re: [NSRCA-discussion] RX choices long club testing results
>
>
>> Bob, I understand how it works. The Carrier signal is still FM and I
>> understand that. The fact that the signal is digitally encoded and how it
> is
>> encoded rejects bad signal or noise or what ever you call it better than
>> straight PPM. I spoke to a semi local Team JR guy at a contest and he 
>> told
>> it was like a little email package with PCM to simplify it. If the email
> was
>> formatted properly then the RX said OK you are my daddy. If the signal 
>> was
>> not formatted properly it would reject it in favor of the proper format
> and
>> if none was found it would do what the Failsafe setting told it to do. In
>> some cases that is Hold the last input on the channel and if you program
> it
>> to go to a specific position it would. In the case of straight PPM if the
> RX
>> sees the signal it passes it through after its been filter and so on. 
>> This
>> is why you see a glitch in FM(PPM) and not in PCM
>>
>> Am I right?
>>
>>
>> I know that F/S doesn't right the model but in reality if you are getting
>> radio interference would you rather have the model do something
> predictable
>> like low throttle and hold other controls or do something totally
>> unpredictable. I have played with F/S in the air by turning my TX on and
>> off. The return of the signal is very very fast like a second or so. My
>> thinking is that if you have enough interference to make the model go 
>> into
>> hold "Lockout" for long enough to crash then I think its reasonable to
>> assume this interference is bad enough that the model may very well not 
>> be
>> controllable?
>>
>> We did some testing last fall at my local club as guys had questions 
>> about
>> this subject. This followed a serious accident in which a 40% model at a
>> Giant Scale fly-in was controlled by a little $60 FM RX and went to full
>> power and cut through the pits and into another modeler. This guy almost
>> died. A tragic event for sure but a $3000 or $4000 model controlled by a
> $60
>> RX? one of our club members was a witness to the event and came home with
> a
>> major agenda for our club to implement. Our club was  looking at a PCM or
>> aftermarket F/S device requirement to help mitigate issues. Our big
> concern
>> is as with all flying sites the homes are getting closer and we don't 
>> want
> a
>> model heading off to meet the local neighborhood.
>>
>> We flew some trainers and foamy models. We took models high and simulated
>> PCM F/S and shoot down situations. For our tests we only used Futaba and
> JR
>> radios. These were higher end TX's as we used the synth capabilities on
> some
>> of the systems to create the issues (JR 9303, 8103, 10X and Futaba 9C'S
> and
>> 9Z's also a 14MZ). We tried lots of different frequencies throughout the
>> band. We used everything from little hitec foamy size rx's to the top of
> the
>> line 14MZ 2048 stuff. In the cases of the PCM system we found that in 
>> most
>> cases the Futaba and JR PCM stuff was pretty bullet proof even in a shoot
>> down. It took a very close TX of the same brand to cause a PCM HOLD
>> condition (our test had engine go to Idle so we could hear it go in and
> out)
>> If the radio brands were mixed JR flying and Futaba as the shoot down it
> was
>> a rare blip of throttle and the longest hold was on the order of maybe a
>> couple seconds. In the case of same brand shoot down the model would go
> into
>> PCM hold for longer until the shoot down TX was off. Then immediately the
>> model was in full control again. Sometimes we could not even tell the
> shoot
>> down TX was on until its antenna was extended or the primary antenna was
>> collapsed partially. If the primary was PCM and the shoot down TX was in
> FM
>> mode it was almost a non existent problem. A very very rare blip of power
>> when the shoot down TX was closer to the model than the primary. And this
>> was only with the shoot down antenna extended more than about 1/3 to 1/2
>> way. In other rare cases the shoot down TX actually became the primary 
>> and
>> started controlling the model. This was rare but we did se it happen. The
>> 2048 didn't do it but the 1024 JR and Futaba stuff could easily. In fact
> we
>> had two 9303's and copied the program between them. We just swapped off
> the
>> TX that was off, then the pilot that was flying would shut his TX off and
>> the next guy turned his on. Man it really was a cool experiment and 
>> proved
>> the reliability and consistency of the systems.Pilot saying ready off, #2
> Ok
>> I'm on, got it.
>>
>> Our club was very impressed with the PCM rejection of the signal. In fact
> I
>> felt the model was in many cases better in control with the PCM holds
> going
>> in and out than the FM responses. The model never flipped upside-down,
> never
>> snapped or went wild. It just held its path and input. If that happened 
>> to
>> be a roll or loop it would continue to roll or loop at the given rate but
>> that was all. The other note was many club members felt PCM hold was a
>> forever lockout thing meaning the hold meant the model was going to crash
>> period and they wanted to have some control. Well we never had that. Once
>> the interference (shoot down TX) was off every single time the primary 
>> got
>> immediate control. And I mean right now as if it never had the issue
> coming
>> back.
>>
>> The FM systems in the same test didn't care about brand of TX, and didn't
>> care about distance or antenna extension on the shoot down TX. In fact
> most
>> cases the models became uncontrolled and while it would still respond to
> the
>> primary TX in the middle of some of the glitching the models were just
>> basically all over the place. It seemed like the RX was passing just any
>> signal through. Of big note if the shoot down TX was FM mode also the
> models
>> were glitchy but the primary could still have an effect not really to fly
>> the model in a save situation but it had an effect. . If the Shoot down 
>> TX
>> was PCM there was no hope. The models were literally all over the place
> and
>> yes some primary control was getting through but you could not rely on 
>> the
>> input to fly the model.
>>
>> We conducted this testing on several weekends and with lots of club
> members
>> present. Yes we took some risks but we really wanted to see if there was 
>> a
>> difference. The result of this test made my local club hit the hobbyshop
>> with a huge order of PCM RX's. I think he sold like (25) JR R770's over
> the
>> course of the next week. The old guys in the club found out their model
> was
>> better protected using the PCM over their FM and it was a black and white
>> comparison. Besides most sport models they guys are flying are in the
>> $400-800 range and what is the extra $40 from the R700fm to the R770pcm.
> Now
>> both of these are Synth so that is cool too.
>>
>> Our club now has requirements for a F/S device or PCM on all models over
>> 7lbs. Why 7lbs? well we felt that we didn't want to discourage trainers
> and
>> new folks starting out, but we did want basically anything 60 sized and
>> bigger to have some F/S capability and the club rule is a safety officer
> can
>> ask you to show it before you fly. I know most of the GS fly-ins in our
> area
>> and the Joe Nall now require this. Before you take off the flightline
>> official asks you to turn off your TX to prove a low throttle setting. 
>> The
>> groans came from the old guys for sure, but in the end they were the ones
>> that really felt the clubs responsibility to our neighbors and to our
> selves
>> was more important. The next thing was a phase in period of 1 yr. We are
> now
>> coming up on that 1yr and the rate of crashes has dramatically reduced at
>> our field. The concern was older FM TX's that could not use do PCM well 
>> H9
>> answered the call with a  $20 F/S module for use on FM systems. Now I
> think
>> there are 3-4 different brands out there. So for the cost of a gallon of
>> fuel and a few props you can have PCM or a FS device for FM.  We have a
> log
>> book that you are suppose to log any crashes or mishaps. We use it to 
>> razz
>> the guys and also to keep track if we have an issue on certain channels 
>> or
>> with a  specific brand or RX or the like. Well the 2005 log book was
> always
>> an issue of radio quit, glitched or what ever. Since the testing and mass
>> exodus to PCM the crashes are greatly reduced and top it off the crashes
> we
>> are having with radio issues are the type of stuff than you would see 
>> like
>> dead battery or bad switch not the mystery glitch or I got hit. Guys now
>> know what radio problems look like and they are diagnosing crashes better
>> and preventing them. Now with everybody flying PCM its really rare to see
>> radio problems at the field. Our field is mostly JR thanks to our
> semi-local
>> Team guy. The most common radio now is the 6102, 8103 and the 9303.
>>
>> Seems that pattern guys tend to spare no expense in the TX department 
>> lots
>> of 9Z's and 10X's as well as the 9303 and 9C systems yet I'm seeing many
> use
>> a PPM RX. My curiosity was peaked as I would have expected nobody to use
> FM
>> in this group. Before the NATs the young man was having issues with his
>> system and when he told us what he was using for servos, leads and radio
>> gear I was shocked. A competition level pilot using aftermarket extension
>> leads and FM Rx'. I was always taught to stay within the brand. Servos 
>> are
>> OK to mix brands with but for switches, extensions, and RX's stay in your
>> own yard the OEM stuff is just a dollar more you have less trouble with
> it.
>> The models are expensive and we spend hours and hours building and
> trimming
>> them up. The real cost in loss of a model is the time trimming and 
>> setting
>> up a new plane to be just perfect. The Money is one side but to me its 
>> all
>> the time and passion working toward the perfect flying model. It sucks
> when
>> you are 1/2 way there or even 99.99999% and the model is gone hit the CLR
>> key in the TX and start over with a new one.
>>
>> Just passing on some experience we had with it. We proved to ourselves
> that
>> PCM not only protected our people and neighbors better but it saved more
>> airplanes too. I understand we really only tested a single condition 
>> shoot
>> down situation and real interference is more random and rare in the real
>> world. We felt that the shoot down was the worst case situation for our
>> field as we are our away from industrial areas and other noisy 
>> environment
>> stuff. We do have some homes about 1/2 mile back behind our pit area to
> the
>> south but models are never flown back there. We have a rule to keep
>> everything North of our runway.
>>
>> By the way lots of guys locally are using the Spectrum DSM as it has a
>> failsafe like PCM and it works great in those small parkflyer models. One
>> guy is even flying it in his 40 sized trainer converted to electric.
>>
>> thoughts?
>>
>> Wayne
>>
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