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Cox Engine of The Month
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MauricioB's

"Cox Tee Dee .010"



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Tach Race 2017- March 11-12 FINAL RESULTS!

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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Oldenginerod on Sat Mar 11, 2017 4:17 am

KariFS wrote:Actually LEDs do "flash" on and off. They don't have a dimming ability other than switching them on and off in a very rapid cycle. Hard to explain, but Google "PWM", it means Pulse Width Modulation, and as far as I understand that is the principle used. It is also widely used in other controller outputs.

You may try pointing a battery powered led light to a propeller, it is possible to see the strobo effect if the rpm and the frequency of your led light are suitable. The different brightness settings the light may have are actually different frequencies of the PWM control.

Also a word of warning: Be careful when working with electrical fans. A led can cause the fan blade to look like it is still, and if there is background noise (or worse still, you use headphones), you don't hear the fan noise... An ouch-moment may occur.

Interestingly, I use LED work/flash lights all the time around running car engines and other rotating components and I can't say that I have ever noticed a hint of strobing effect. Where I bench run my engines there is not a lot of daylight and the fluorescent lights are pretty high up to have any negative effect, so I need to provide another light source when taching an engine. I have always used an LED flashlight behind the prop pointing at the tach and have only ever had reliable and steady results. LEDs don't produce any reading on my tach like fluorescent lights do.
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  KariFS on Sat Mar 11, 2017 9:21 am

Rod, the phenomenom happens only with the kind of led lights that have a dimming possibility, and more probably with the cheaper units where the PWM switching frequency is lower. Like my 3€ light with a head mounting strap Smile

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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  RknRusty on Sat Mar 11, 2017 10:53 am

KariFS wrote:Rod, the phenomenom happens only with the kind of led lights that have a dimming possibility, and more probably with the cheaper units where the PWM switching frequency is lower. Like my 3€ light with a head mounting strap Smile

The one I used had variable brightness settings.


!!!!!TACH RACE!!!!!

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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  RknRusty on Sat Mar 11, 2017 11:04 am

Post office says mine is on the delivery truck.

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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Cribbs74 on Sat Mar 11, 2017 12:17 pm

It's all good Rusty, I'll run unlimited tomorrow.

Woke up this morning feeling crummy. Had some breakfast and coffee and motrin. Headed out now to get this going. Weather is 39 degrees overcast and misty. Not the best... no rain though. I'll report back this evening, if not then tomorrow. Good luck to everyone!
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Oldenginerod on Sat Mar 11, 2017 3:05 pm

Go well Ron. Don't get too fussy about running everything in exactly the same conditions. the differences in RPM will only be marginal, but the difference in stress level for you could be massive. Do your best & eveyone will live with the results. If you get any complaints over how you do it, tell 'em to run it themselves next year. It's just for fun. The prizes are fantastic, but unfortunately when there's something valuable up for grabs people's attitudes change & they become more competitive. Often it's the organizers that receive the brunt of their frustration.
Hopefully everyone will leave you well alone & appreciate your efforts. Have fun!
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Kim on Sat Mar 11, 2017 5:47 pm

Don't know how Rod drew a negative on his comment. This IS supposed to be a for-fun event, and I can tell you that anyone who respects other peoples' property and then sets themselves up for being responsible their engines for something like this IS pulling down some stress.

Don't let the Tach Race Gremlins get you Ron, seemed like I was always getting some kind of cold right in time for the race !!!
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Cribbs74 on Sat Mar 11, 2017 6:15 pm

Ok guys,

Running out of daylight. I wasn't as prepared as I thought, spent a couple hrs setting up, but I did get get through stock and TD. I'll do mouse and Unlimited tomorrow. Wish you guys had left a note in the box as to which engines you wanted run in what class. Hopefully I'll figure it out, but if you see this shoot me a PM and make my life easy.

Fred, impressive TD! however...better start looking for a TD crankshaft Shocked
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Oldenginerod on Sat Mar 11, 2017 6:53 pm

Kim wrote:Don't know how Rod drew a negative on his comment.

Yeah, waddid I say?  Was just trying to encourage Ron. Sad
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  roddie on Sat Mar 11, 2017 7:03 pm

Oldenginerod wrote:
Kim wrote:Don't know how Rod drew a negative on his comment.

Yeah, waddid I say?  Was just trying to encourage Ron. Sad

I don't pay much attention to that stuff.. Don't give it a second thought Rod.
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  KariFS on Sun Mar 12, 2017 3:04 am

roddie wrote:
Oldenginerod wrote:
Kim wrote:Don't know how Rod drew a negative on his comment.

Yeah, waddid I say?  Was just trying to encourage Ron. Sad

I don't pay much attention to that stuff.. Don't give it a second thought Rod.

Most likely just fumbly fingers on someones touchscreen. I agree with the guys, this is supposed to be a fun event, just as the photo contest.

I think it is great that you do this, no reason to stress over it.

I hope I'll have something to enter someday Smile
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  getback on Sun Mar 12, 2017 8:21 am

Ron , you are a Trooper at 39 degrees !! I had put a pic of my engines in the bottom of the box telling witch engines were for what race . Fred i have some TD cranks if you need one ?!!?! Smile This Site Rocks!
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  fredvon4 on Sun Mar 12, 2017 9:11 am

Don't have my notes* for that TeeDee but no matter, I have many more cranks than good cases...

Again many thanks to Ron for doing this event

* this is one of the 4 engines I fussed with trying to find if the so called high performance cranks were worth the effort and at same time playing around with venturi size

I am surprised Ron could even get it to run on a hard tank as ALL my TeeDees are bladder setup
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  RknRusty on Sun Mar 12, 2017 12:11 pm

fredvon4 wrote:I am surprised Ron could even get it to run on a hard tank as ALL my TeeDees are bladder setup
For bench running a TD with a bored venturi(for pressure bladder), I raise the tank until it siphons by itself and clamp off the line. Then proceed like you're cranking a bladder; prime if it isn't already wet, crank and remove the line clamp while it's burning off the prime. The gravity feed will keep it going.
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Marleysky on Sun Mar 12, 2017 2:13 pm

KariFS wrote:Rod, the phenomenom happens only with the kind of led lights that have a dimming possibility, and more probably with the cheaper units where the PWM switching frequency is lower. Like my 3€ light with a head mounting strap Smile


If your filming(video) and set the frame rate the same as the prop rotation you get this:

https://petapixel.com/2017/03/04/cameras-frame-rate-synced-helicopters-rotor/
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  RknRusty on Sun Mar 12, 2017 5:38 pm

Marleysky wrote:
KariFS wrote:Rod, the phenomenom happens only with the kind of led lights that have a dimming possibility, and more probably with the cheaper units where the PWM switching frequency is lower. Like my 3€ light with a head mounting strap Smile


If your filming(video) and set the frame rate the same as the prop rotation you get this:

https://petapixel.com/2017/03/04/cameras-frame-rate-synced-helicopters-rotor/

That's too cool!. There is a good video about that on howstuffworks.com but now I can't find it.

I wonder how Ron is doing.

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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Cribbs74 on Sun Mar 12, 2017 7:16 pm

Dealing with seriously overcompressed engines!!!! lol!
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  RknRusty on Sun Mar 12, 2017 8:12 pm

I actually lowered my compression figuring it would be cooler there. I hope it at least cranked Lol.

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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Cribbs74 on Sun Mar 12, 2017 10:56 pm

In light of the recent news of Joe's passing I am going to post results tomorrow.

Ron
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Oldenginerod on Mon Mar 13, 2017 5:42 am

Cribbs74 wrote:In light of the recent news of Joe's passing I am going to post results tomorrow.

Ron

Good call Ron.
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Kim on Mon Mar 13, 2017 11:48 am

Yes.
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  Cribbs74 on Mon Mar 13, 2017 8:26 pm

Ok Gentlemen it's time for the results.

Before I get into that, Let me just say that I appreciate everyone for trusting me with your little gems. It was an honor to be able to CD this event.

The numbers might not be what you are expecting. They were down from the last go around, nearly every engine was over-compressed some so much so that it took me a good long while to get them to fire. Humidity was high and temps were low, not sure if that played into it, but it is what it is.

So without further ado....

Stock

1st place Bill M.-17,770 Golden Bee
2nd place Eric G- 16,570 Babe Bee
3rd Rene W- 14,440 Babe Bee

TD

1st Fred VG - 24,420 before the crank pin let go lol!
2nd Rene W- 22,800
3rd Eric G- 22,550

Mouse

1st Doug V.- 20,610
2nd Kim S.- 18,390

Unlimited

1st Eric G.-20,890
2nd Kim S.-20,280
3rd Rusty Nail- 19,750

Roddie-19,560
Bill M.- 19,530
Exmodelengines(Matt)- 19,290
Doug V-19,220
Cox International(Bernie)- 19,120
Rene W. 18,770
Fred VG-18,510







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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  crankbndr on Mon Mar 13, 2017 9:11 pm

Wow Ron thanks for the contest!! Surprised theres only two Mices, I try not to get mine too compressed, sorry if they were hard starters.
I get em running well here where its hot and humid and remove one shim because it will be cooler at the contest.
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  getback on Mon Mar 13, 2017 9:26 pm

cheers Beer Cheers cheers Ron you THE MAN !! Yes it was warm here and low Hu. at the time of test ;; Thanks for making it happen , Eric bounce Thumbs Up
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

Post  RknRusty on Mon Mar 13, 2017 9:45 pm

Awright! That's the old Mudhen plain-faced RR-1, good show.
lol! "Rusty Nail..." my club appointed name lives on.

Thanks, Ron.
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Re: Tach Race 2017- March 11-12 FINAL RESULTS!

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