Igor Burger's active timer scare

[Matt Piatkowski]

Igor Burger's active timer scare on August 03, 2022.

The system: Plettenberg 15-22, 11x6x4 carbon laminate propeller, 6S TP 2800, Spin66F2B and Igor Burger's active timer.
The model: Big Red, current RTF weight 1812 grams (63.9 oz.).

I have changed the Target Throttle (TT) value from 123 to 125. This was the only change.
Max. Throttle was and is 180 and Min. Throttle: 66.
Sensitivity: 50
Delay: 35 sec.
Time of flight: 5 minutes 20 seconds

I have used calibration = 001 after changing the TT from 123 to 125 and flew horizontally for 11 laps.
During the 12th. lap the RPM went up for a moment only and the motor stopped.

Measured lap time was 5.26 -5.28 seconds and this is what I wanted.
( With TT=123 the lap time was 5.32-5.33 seconds and it was a bit too slow for my model in it's current configuration in certain corners.

The first pattern flight after calibration flight was ok. In preparation for second pattern flight,  I have inserted fully charged and balanced battery (I always check the battery immediately before using it) and flipped the switch ON. I heard the beep, walked to the handle and, after 35 seconds ( as programmed in the active timer), the model took off. The model flew three horizontal laps and the motor stopped. I landed and shouted “hold the plane” to the guy who was my helper . Before he could do it, the motor started again but with lower RPM. The model was taxiing with moderate speed for 1/4 of the circle and then, suddenly, the RPM went up and the model was flying again. I kept it flying horizontally for five laps and then the motor stopped. I landed, my helper grabbed the plane and the disaster was luckily avoided.

It looks for me that the active timer “went stupid” for some mysterious reason.
I am using Igor's active timer since 2017 but I have never seen anything like that.

I have checked the entire setup of the active timer and Spin 66 F2B and found nothing suspicious.

Now what???...Fly or not to fly: this is a question.

M

[Brett Buck]

Igor Burger's active timer scare on August 03, 2022.

The system: Plettenberg 15-22, 11x6x4 carbon laminate propeller, 6S TP 2800, Spin66F2B and Igor Burger's active timer.
The model: Big Red, current RTF weight 1812 grams (63.9 oz.).

I have changed the Target Throttle (TT) value from 123 to 125. This was the only change.
Max. Throttle was and is 180 and Min. Throttle: 66.
Sensitivity: 50
Delay: 35 sec.
Time of flight: 5 minutes 20 seconds

I have used calibration = 001 after changing the TT from 123 to 125 and flew horizontally for 11 laps.
During the 12th. lap the RPM went up for a moment only and the motor stopped.

Measured lap time was 5.26 -5.28 seconds and this is what I wanted.
( With TT=123 the lap time was 5.32-5.33 seconds and it was a bit too slow for my model in it's current configuration in certain corners.

The first pattern flight after calibration flight was ok. In preparation for second pattern flight,  I have inserted fully charged and balanced battery (I always check the battery immediately before using it) and flipped the switch ON. I heard the beep, walked to the handle and, after 35 seconds ( as programmed in the active timer), the model took off. The model flew three horizontal laps and the motor stopped. I landed and shouted “hold the plane” to the guy who was my helper . Before he could do it, the motor started again but with lower RPM. The model was taxiing with moderate speed for 1/4 of the circle and then, suddenly, the RPM went up and the model was flying again. I kept it flying horizontally for five laps and then the motor stopped. I landed, my helper grabbed the plane and the disaster was luckily avoided.

It looks for me that the active timer “went stupid” for some mysterious reason.
I am using Igor's active timer since 2017 but I have never seen anything like that.

I have checked the entire setup of the active timer and Spin 66 F2B and found nothing suspicious.

Now what???...Fly or not to fly: this is a question.

M

  Could be a lot of things, tin whiskers, other conductive debris, cracked traces or solder joints almost anywhere, piezoelectric effects from unfortunate materials around it.

     Brett

[Ken Culbertson]

  Could be a lot of things, tin whiskers, other conductive debris, cracked traces or solder joints almost anywhere, piezoelectric effects from unfortunate materials around it.

     Brett

So, we have traded holes in the fuel lines and a loose spray bar for tin whiskers and piezoelectrical discharges. Progress? 

I love this hobby - Ken

[Lauri Malila]

So, we have traded holes in the fuel lines and a loose spray bar for tin whiskers and piezoelectrical discharges. Progress? 

I love this hobby - Ken

Put the timer under water and blow into any of the cables. Look for bubbles. I hope this helps. L

[John Rist]

Put the timer under water and blow into any of the cables. Look for bubbles. I hope this helps. L

Make fun if you want but there must be something good about electrics.  All 4 US team members to the world Championships are flying electric.   

[Lauri Malila]

Or, my stuff is out of their reach?🤭

[Ken Culbertson]

Make fun if you want but there must be something good about electrics.  All 4 US team members to the world Championships are flying electric.   

If you get bubbles, replace the timer.  If you don't, you just ruined it so replace the timer.  Actually, I am amazed that these things are as reliable as they are.  "Computers", big or tiny like a timer or ESC all have an error rate.  It may be 1 in a million packets fail.  Sounds like a big number.  In today's laptop that would mean the computer made 1,000 errors a second.  What it does with those errors at the CPU, OS, language and application levels gives us what we have today which is pretty darn reliable.  Still "Sh** Happens" and a random error may make it all the way to the application level where we live.  Writing application code that can handle errors is as time consuming as writing the application itself.  Brett's choice of words may sound comical, but he is 100% on target. So many things can affect the electronics.  The one we all probably ignore is the placement of the magnets, especially hatch magnets, in our systems. A lot of the errors we get are random and difficult to duplicate and that is why we need to pay extra attention to safety with electric.

Ken

Apologies to John, this was supposed to be in response to Lauri.

[AMV]

"SURPRISE!!!" mode is a hidden feature of every electric system.
Plan accordingly.

 
-Andrey

[jerry v]

People who believe in 100% reliability of electronics also believe Santa Claus is real.

Jerry

[EricV]

"SURPRISE!!!" mode is a hidden feature of every electric system.
Plan accordingly.

 
-Andrey

They are called software Easter Eggs, you get a surprise when they are found. Maybe if you listen closely to the on-off sequence of the motor you will recognize Igor's favorite song? Or Morse code spelling out "Fly F2B!" Ok Ok... enough silliness.

Having a background in consumer electronics, I can tell you this much, once something used in a mission critical environment is suspect, you replace it, and carve a swath around it like a cancer and replace nearest adjacent connectors & components along with it... unless you enjoy re-building after re-kitting your plane. It might seem a hard pill to swallow, but I would consider it buried into "the cost of doing business" as we like to say.

Reminds me of a story... My first real job (not counting kiddie jobs like paper routes) while still in High School was an apprentice bench tech at a TV repair shop... They were a G.E. factory service center.

G.E. used Solder Griplet Pools that were basically a rivet used to tie a top trace to the back of the board on double sided boards, and cold soldered at the factory... There were several on a given board. I had to deal with those in the television sets in the early 1980's... TV's would come in with all manner of intermittent problems (a techs worst nightmare, because you never knew if you really nailed it)... then we got the Tech Bulletin from GE saying to "reheat the solder griplet pools until the problem abated". I thought, this has to be a joke! Griplets were a horrid idea, I would hate to think people's lives ever relied on circuit boards using those. The tech was fraught with problems as even a layman could imagine with heat/cold cycles involved in an old CRT TV, which lead to cracked lead pools and unstable connections. I spent many an hour tracing and re-heating those things... at jobber flat rates, meaning we got $35 for the repair from G.E. whether it took me 1hour, or 4hours...yuck! Some came back again same problem after a few months, so I amended GE's repair option and I started using my own solder in the pools, removing whatever the factory solder was with a sucker, it was junk, and those seemed to "stay fixed" longer.

Back to your scare, all I can say is I'm truly sorry but don't trust it until you can. (no, I'm not doing my Yogi Berra impression, well, ok, maybe a little)

EricV

[AMV]

Given the environmental stresses that the typical stunt model and its guts is subjected to during its lifetime (heat, humidity, UV, etc.), this incident makes me wonder whether conformal coating would alleviate issues like these, or at least prolong the life of timer PCBs.

This is only my guess -- for example, I consider ESC manufacturers to be on the "commercial" level, so I'd expect that they provide conformal coating on their products (but I don't know for a fact).  Our timer manufacturers are on a much smaller production scale and what I'd consider to be "cottage industry" level, where such treatment is likely optional.
Just some food for thought.


- Andrey

[Brett Buck]

Given the environmental stresses that the typical stunt model and its guts is subjected to during its lifetime (heat, humidity, UV, etc.), this incident makes me wonder whether conformal coating would alleviate issues like these, or at least prolong the life of timer PCBs.

This is only my guess -- for example, I consider ESC manufacturers to be on the "commercial" level, so I'd expect that they provide conformal coating on their products (but I don't know for a fact).  Our timer manufacturers are on a much smaller production scale and what I'd consider to be "cottage industry" level, where such treatment is likely optional.
Just some food for thought.

   It might solve a few of the potential problems. But tin whiskers, for example, go right through it. One of the things I have been concerned about with the European-based systems is that they probably use RoHS-compliant solder and plating - meaning the possibility of pure tin, which is notorious for tin whicker growth.

     But it is probably a lot simpler and more prosaic - like an intermittent connection or cracked trace somewhere. Paul's problem on Top 20 day was fortunate in one way, it quit, started back up, and ran out the timer. Suppose instead that it just quit and he landed. Then, you have no notion what the internal state or situation might be. It might start up at full speed as soon as you touch it and jostle the connection, better be ready for that (and recall that it pulls 4-6 lbs on the ground - better grab it pretty well). This seems to be very similar to what happened to Matt. 

     This is the sort of thing that led to the arming rule, but you still have to be very careful when something unexpected happens. BTW, I have heard about 20 reports of something similar to the case Matt describes, and it is certainly not unique to the Jeti components, pretty much any variety might do something similar.

      You have to always recall you are operating a relatively high-power device with very minimal safety provisions and are largely unable to determine anything about the state of the electronics just by looking at it*, BE CAREFUL.

      Brett

*I would also suggest that it would be a good application for telemetry or, something like Howard's status lights, so you would at least have a vague notion what it is doing from the outside.

[jerry v]

Everything on Earth has a lifespan .
My best experience was with Castle Creations 85 HV speed control. It started flying in 2006 in my RC model Hangar 9 P-51 Mustang PTS ARF. It flew for 10 years without any problems. It still flying on YouTube video)). Weight- 9 pounds, Motor - E-Flite 60, prop -APC 15x10 E, originally was on 20 cell NiMH batteries, later it was 6 cell 5000 mAh lipo. ESC survived constant 50 Amps 1250 Watts all those years. I was using receiver battery for controls , I think it’s more reliable than UBEC. Gradually I replaced all sport JR servos with Futaba all metal servos . Model was pushing 105 MPH on police radar in a speed  contest.
And one day after plugging in and turning on switch ESC did not make a sound. It only wiggle the prop and died with dignity. There was no smoke, no fire.
I think Patrick  Castillo should have a Hall of Fame for this ESC…

Jerry

[AMV]

   It might solve a few of the potential problems. But tin whiskers, for example, go right through it...

I was thinking of a coating more substantial than the typical <250um thickness.  I've seen it on at least one COTS product (outdoor temperature sensors).  Something around 1 mm thickness. Even just visually it looks like it would stand up to long-term environmental and mechanical abuse.

 
-Andrey

[Brett Buck]

I was thinking of a coating more substantial than the typical <250um thickness.  I've seen it on at least one COTS product (outdoor temperature sensors).  Something around 1 mm thickness. Even just visually it looks like it would stand up to long-term environmental and mechanical abuse.

     Typical urethane conformal coating doesn't stop them as a general proposition. Maybe, some sort of harder coating (plasticized epoxy) would be more appropriate, but that creates other problems.

   The solution is to get rid of nearly-pure-tin materials, which you could do with the solder - suck it off and redo it with 63/37, but not with any tin plating. I don't know if this is a real problem for these controllers, I note that the failures have not been diagnosed,  Matt's in particular.

        Brett

[AMV]

Hoping to hear more from Matt regarding the diagnosis.
I'm willing to bet my rusty $0.02 that it's a loose or oxidized wiring connection somewhere...

 
-Andrey

[John Rist]

Hoping to hear more from Matt regarding the diagnosis.
I'm willing to bet my rusty $0.02 that it's a loose or oxidized wiring connection somewhere...

 
-Andrey

AVM probably has nailed it.  During my 40 years working with military and space electronics most of the failures were bad solder joints and broken wires. 

[Steve Helmick]

Put the timer under water and blow into any of the cables. Look for bubbles. I hope this helps. L

 

[Ken Culbertson]

But the tank is the battery, maybe we should skip this test.

Ken

[Joe Gilbert]

Remove system ,run over with your car and put new system in. It seams no one will say it ,but that is exactly what need to happen. It will fail you and cost you a plane.


Regards

Joe Gilbert

[Paul Walker]

After further investigation of my failure, it turned out to be a faulty male Deans connector. This one was original to this ESC  which is now 10 years old. It, the connector, is from my early days of electric  circa 2007. It does not have the "tin" arched strip on it to apply force to maintain contact.

How it worked perfectly for 10 years and then decide on THAT flight to have a discontinuity is just, well, bad luck.

Matt, you might want to look closely at your connectors.

[Steve Helmick]

After further investigation of my failure, it turned out to be a faulty male Deans connector. This one was original to this ESC  which is now 10 years old. It, it connector, is from my early days of electric  circa 2007. It does not have the "tin" arched strip on it to apply force to maintain contact.

How it worked perfectly for 10 years and then decide on THAT flight to have a discontinuity is just, well, bad luck.

Matt, ypu might want to look closely at your connectors.

Was Shal the one that discovered the fault? It's always the male's fault, you know!  Steve

[Dave Hull]

One of the things that needs plenty of attention if you want a high reliability CCA are the thermal stresses and differential expansion in the overall assembly. High power circuitry is obviously an area of concern, but it really has to do with the power density on each package and the method (or lack thereof) of heatsinking. So, a unit with a very well-designed power converter can be fine, but the logic device next to it can get fried because no one looked at that. Lots of failures occur due to lead fracture inside the package. Insidiously, these can appear to work until the package starts to come up to temperature--and then they open up. And, if cooled, they suddenly can start working again. You can buy a "can of cold" to spray on likely components if you have to troubleshoot this kind of failure.

Coating a CCA with ever-thicker layers of conformal coat is not the solution. It is there for other reasons, such as:
--reducing corrosion, especially in outdoor equipment
--providing some protection against conductive FOD, such as carelessly trimmed wire strands, solder balls, etc.
--warranty evaluation: it is easy to detect tampering on items if they have been conformal coated. Rework is made much harder....

Don't even get me started on tin whiskers....  The most excellently egregious example I ever saw was in an old Hammond organ. A truly awesome spectacle for someone that used to work in aerospace....  There is even a related tuner bulletin that has you bonking and sweating to repair it....  Tubes Forever!

[Brent Williams]

Don't even get me started on tin whiskers....  The most excellently egregious example I ever saw was in an old Hammond organ. A truly awesome spectacle for someone that used to work in aerospace....  There is even a related tuner bulletin that has you bonking and sweating to repair it....  Tubes Forever!

Ah yes, the ol' choppy vibrato, motorboating Hammond B3 with a non-functioning percussion switch...the evil formation of zinc dendrites in the scanner, switches, ect.  The chassis were coated in Zinc. 

[Dan McEntee]

After further investigation of my failure, it turned out to be a faulty male Deans connector. This one was original to this ESC  which is now 10 years old. It, it connector, is from my early days of electric  circa 2007. It does not have the "tin" arched strip on it to apply force to maintain contact.

How it worked perfectly for 10 years and then decide on THAT flight to have a discontinuity is just, well, bad luck.

Matt, ypu might want to look closely at your connectors.

   If you don't mind a guess from an IC flier, I would just call it "wear and tear."  You guys pump a pretty fair amount of current through those connectors, and they are a pretty major point of resistance. From my experience with flying electric R/C sailplanes using lesser quality connectors, and in industrial applications, the repeated heat/cool cycles tends to relax the female side of things, and then this increases the resistance and makes in worse in minute increments until you get a failure or at least start seeing signs of the connectors overheating. Back in my R/C sailplane days we didn't have the nicer connectors there are now available and they had to be watched like a hawk. We tended to hard solder as many connections as possible just leaving the most necessary for charging. I used to see it a lot in industrial applications also where vibration made it worse. On any kind of intermittent problem, the first thing I would check was any connectors involved. You just got a visit from Murphy's Law that day.

  Type at you later,
    Dan McEntee

[Guy Markham]

   If you don't mind a guess from an IC flier, I would just call it "wear and tear."  You guys pump a pretty fair amount of current through those connectors, and they are a pretty major point of resistance. From my experience with flying electric R/C sailplanes using lesser quality connectors, and in industrial applications, the repeated heat/cool cycles tends to relax the female side of things, and then this increases the resistance and makes in worse in minute increments until you get a failure or at least start seeing signs of the connectors overheating. Back in my R/C sailplane days we didn't have the nicer connectors there are now available and they had to be watched like a hawk. We tended to hard solder as many connections as possible just leaving the most necessary for charging. I used to see it a lot in industrial applications also where vibration made it worse. On any kind of intermittent problem, the first thing I would check was any connectors involved. You just got a visit from Murphy's Law that day.

  Type at you later,     You just got a visit from Murphy's Law that day ? Must have been O'Brien's Law  (He said Murphy was an optimist)   

[Brett Buck]

After further investigation of my failure, it turned out to be a faulty male Deans connector. This one was original to this ESC  which is now 10 years old. It, it connector, is from my early days of electric  circa 2007. It does not have the "tin" arched strip on it to apply force to maintain contact.

   This was on the signal side, not the power side?

   Brett

[Howard Rush]

I had a Dean’s connector fail at GSSC. While installing the battery I saw the green light flicker. I pulled the battery connector and the spring fell out. I jammed it back in and flew my first flight. I crammed a piece of solder in the connector for the second.

[Lauri Malila]

Just a thought Matt, but have you asked from Igor? He might have an idea.. L

[Paul Walker]

   This was on the signal side, not the power side?

   Brett

On the input side of the ESC. Battery to ESC.

[Matt Piatkowski]

Guys,
Thank you for your thoughts.
Yesterday, I performed three ground tests with a 9x5 Graupner electric propeller.
Each test was 5 minutes and 20 seconds long with an average current of about 7 Amps.

I wanted to see if I could replicate the unexplained timer behavior.
I could not.

From flipping the switch to the end of the tests system performed flawlessly.

I have disconnected and checked under the magnifying glass all connectors and found no corrosion, no loose/broken connector parts, and no dirt. I am currently trying to assess the wires/cables close to the soldered joints.

I wrote to Igor, but he is competing right now. I will be in Kruszyn (Aeroklub Wloclawski) tomorrow around 7 AM. and will try to talk to him.

Regards,
M

[Brett Buck]

On the input side of the ESC. Battery to ESC.

  So, the timer kept getting power, it was fine, but the PWM  drive signal was turned off intermittently. That's probably the most dangerous failure mode, since it could spool down and just sit there until someone moved it, etc, then it would turn on suddenly at full blast - which is more-or-less what happened, for brief periods. 

    Brett

[Dwayne Donnelly]

After further investigation of my failure, it turned out to be a faulty male Deans connector. This one was original to this ESC  which is now 10 years old. It, the connector, is from my early days of electric  circa 2007. It does not have the "tin" arched strip on it to apply force to maintain contact.

How it worked perfectly for 10 years and then decide on THAT flight to have a discontinuity is just, well, bad luck.

Matt, you might want to look closely at your connectors.

This is the Schulze  esc and Doherty/McKenzie timer?

[Lauri Malila]

……ghhh

[Paul Walker]

  So, the timer kept getting power, it was fine, but the PWM  drive signal was turned off intermittently. That's probably the most dangerous failure mode, since it could spool down and just sit there until someone moved it, etc, then it would turn on suddenly at full blast - which is more-or-less what happened, for brief periods. 

    Brett

It was the full power side, full V and A  and not the timer connection. The power to the ESC was cut, and it had no power, then the g load stopped, and the plug moved and made contact, and ran.    I killed it wirh a tight loop later in the flight.

[Claudio Chacon]

Put the timer under water and blow into any of the cables. Look for bubbles. I hope this helps. L

HAHAHAHAHAHAHAHAHAHAH!!!!! 

[Brett Buck]

It was the full power side, full V and A  and not the timer connection. The power to the ESC was cut, and it had no power, then the g load stopped, and the plug moved and made contact, and ran.    I killed it wirh a tight loop later in the flight.

  Timer is still going, so it just starts up again when it gets power.

    Proving how ignorant I am, how does the timer get power?  It's own battery connection, or the ESC? I am asking because I am trying to figure out how you could kill or reset the timer to "off" if you get an intermittent power to the ESC. One *hopes* that the timer generates its own reset signal to put it to quiescent if the power is interrupted, so it won't just keep going if the power comes back. Particularly since this is 3 variants on this theme in the last 2 weeks - one of which was disastrous from a competition standpoint, the other two being safety issues.

    Brett

[Ken Culbertson]

    Proving how ignorant I am, how does the timer get power?
    Brett

I think you have asked a question a lot of us would like answers to.  I am pretty sure it gets it from the ESC but is it dependent on that power being continuous and if there is a short break does it discharge and reset awaiting the start button or keep running?

This thread is having a positive effect.  Flew Friday and I found myself with the arming plug in the front of my mind instead of an afterthought when moving the planes around.

Ken
 

[Dwayne Donnelly]

Yes the timer gets power from the esc same as the esc powers a reviver and servos in a RC application.

[Brett Buck]

Yes the timer gets power from the esc same as the esc powers a reviver and servos in a RC application.

   That's interesting, because that suggests that the caps in the timer hold it up long enough to stop for some considerable time, but start up again, and that no reset signal is set if power is interrupted.

   I really need to get some of this stuff, set it up on the bench and figure out what signals go where. Maybe not important for just fixing intermittent connections, but I am cursed with curiosity and a pathological need to turn every problem into a use case for a feedback control system.

    Brett

   

[Matt Piatkowski]

Hi Lauri,
I was all day yesterday at the F2B main circle and could not see the event you have described.
Was it Moti Salem's model?

I feel that your diagnosis is right and I will make sure THIS particular ribbon cable is replaced and protected from random bending.
Please see the attached.

I will try to find you on Tuesday to say hello.
Thanks,
M

[Lauri Malila]

Yep, it was Moti’s model.
On the bright side, now I can say that I’ve flown electric, too😂.
Looking forward to meet you. L

[Ken Culbertson]

I feel that your diagnosis is right and I will make sure THIS particular ribbon cable is replaced and protected from random bending.
Please see the attached.

I have spent most of my professional career working with ribbon cables.  They are very delicate especially if the wire has thick strands.  One thing that I absolute avoid is removing them or constantly bending them.  I have routed the Jetti Box cable for my timer to a port on the side of my plane and all of the other connections are completely out of the battery area.  In other words, nothing is moved by changing a battery or changing settings on the timer, and the cables themselves are secured.  Granted, it is a pain to reprogram the ESC but how often do we do that once the initial settings are arrived at.  Maybe someday the Jetti folks will give us a separate cable to program the ESC without having to remove the timer.  The absolute worst place is right where the wire exits the connector.  I am used to reinforcing that area on a small connector that gets removed frequently with a short strip of electrical tape,  but I have not been doing it on my planes.  That stops now.  Surely there is a product designed to reinforce ribbon cables.  Sugru has been used but it is rather bulky.  Epoxy is too hard. Silicon is a semiconductor.  Perhaps FlexSeal or Liquid Rubber? 

A quick note on preventative maintenance.  When I was in fighter maintenance business during the war we try and forget, most of the problems we had came right after routine maintenance.   Most were human error but not all.  The Navy had more of a "if it isn't broken, don't fix it" attitude.   The vibration and G-Forces in a jet fighter are similar to what we encounter, and they have the same problem we do - how do you check it under a high G turn on the ground?  Any wire that can chafe probably will in time then moving it to check something else breaks it.     

Ken

[Scott Richlen]

Lauri:

What engine was that?  (you posted a picture of previously)

It looked good!

[Reptoid]

It was the full power side, full V and A  and not the timer connection. The power to the ESC was cut, and it had no power, then the g load stopped, and the plug moved and made contact, and ran.    I killed it wirh a tight loop later in the flight.

Hi Paul; Just some info: I have seen numerous problems on the high current (red two pin) Dean's connectors in electric sailplanes which was death to airplane if they were using a BEC with the ESC to power the receiver as the momentary loss of main power causes both the ESC and the receiver to go into "power up reset". I switched all of my stuff to XT-60's. Better design (IMHO) easier to work with and almost impossible to short. Most of the helicopter guys I know also use the XT-60 (XT-90 on Mega Watt rigs)

[PerttiMe]

Lauri:

What engine was that?  (you posted a picture of previously)

It looked good!

Lauri has built some engines of his own. He has the skills and the tools. Not sure if they have been posted here but I found some on a local forum.

[Matt Piatkowski]

Hi Ken,

I will route the ribbon cable from the active timer inside the battery compartment but in such a way that inserting and removing the battery will not cause accidental bending in this ribbon cable or/and its sleeve (shown in the attachment I sent to Lauri).
The front of the fuselage of Big Red is wide enough for that.

I still do not know how to secure the sleeve itself to allow for connecting and disconnecting the JR connector from Spin66F2B. When the sleeve is immobilized on the inside fuselage skin, it is not easy to do it. Perhaps I would have to design and make a special tool for this task?

Another potentially dangerous issue is the "health" of the ribbon cable leading from Spin66F2B to the sleeve. Let me think about it.

You have mentioned the G forces effects. Certainly when the ribbon cables suffer from 8-12 G in sharp corners they will try to move. Unfortunately, we will never know how much and where. In other words: the deflection mode under G loading is and will remain unknown.

We may immobilize every inch of the ribbon cables only to find that they failed due to fatigue shear and bending on one of the attachments.

This brings an interesting question: how to assess "health" of thin copper wire bunches covered by insulation in each ribbon cable?
Such "Health Check" should be performed after, say, 100, 300, 500 and 1000 pattern flights but how to do it?? 

Another interesting issue is simply the size of many parts/elements in model building. Some of them are so small that even working with the magnifying glass, good directional light and steady hand cannot guarantee quality. In other words: the quality of our work is only statistical and has random errors distribution. The "Art of Small" is rather art than science.

Thank you for your input.
Best Regards and Happy Flying,
M

[Scott Richlen]

Quote from: Scott Richlen on Yesterday at 12:40:33 PM
Lauri:

What engine was that?  (you posted a picture of previously)

It looked good!
Lauri has built some engines of his own. He has the skills and the tools. Not sure if they have been posted here but I found some on a local forum. 

PerttiMe: The engine is pictured in Reply #5 of this thread.  It is very attractive.

[Paul Walker]

Hi Paul; Just some info: I have seen numerous problems on the high current (red two pin) Dean's connectors in electric sailplanes which was death to airplane if they were using a BEC with the ESC to power the receiver as the momentary loss of main power causes both the ESC and the receiver to go into "power up reset". I switched all of my stuff to XT-60's. Better design (IMHO) easier to work with and almost impossible to short. Most of the helicopter guys I know also use the XT-60 (XT-90 on Mega Watt rigs)

Thanks. That is a serious consideration.

[PerttiMe]

PerttiMe: The engine is pictured in Reply #5 of this thread.  It is very attractive.

I meant that he might have posted something on it before.
On the local forum, I found some in-progress pics, from some years ago.