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Cox Engine of The Month
February-2024
1/2A Nut's

"RC Speed Boat Power Drive TD .020"

More info on this engine!




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Dragon Extreme tached at last Empty Dragon Extreme tached at last

Post  John Goddard Wed Feb 06, 2013 6:19 am

OK
So finally 'warmed' up enough and stopped raining long enough to nip away from work
to do the really important stuff...
London 11.00 AM 3 degrees C.
21,570 peak
holding 20,400
25%, Bernie wobblemeister 5x3 4 gaskets

Running in process coming along nicely, a little more to come I'm sure.

Remember guys this is throttled/still got set the low run up and tweak the throttle curve on the Tx.

Benchmark for the Vid tach comp?
Flying

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Post  Surfer_kris Wed Feb 06, 2013 6:31 am

Nice numbers, but isn't it the wrong prop, fuel and tach for the race? lol!
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Post  John Goddard Wed Feb 06, 2013 7:08 am

Thanx Kris
I've just had to disqualify myself.
lol!
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Post  Cribbs74 Wed Feb 06, 2013 1:01 pm

Should be zippy JB!!!!

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Post  WingingIt74 Thu Feb 07, 2013 3:12 pm

I sure like those safety yellow props, but your tach will be much higher. It surprised me how much different it was with my Killer Widow.
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Post  John Goddard Fri Feb 08, 2013 5:30 am

WingingIt74 wrote:I sure like those safety yellow props, but your tach will be much higher. It surprised me how much different it was with my Killer Widow.

Classic lol!

In the flight vid it has a black 5X3 prop (not sure what if any differnce) yet the 11.5 oz
aircraft (20cc of fuel) takes off and has vertical performance ie it's producing a lot more thrust than
11.5 oz.

Take a look at,- http://personal.osi.hu/fuzesisz/strc_eng/index.htm

Put in 19000 rpm on a 5x3 it doesn't produce enough thrust for vert flight.

Cos the weather is going to be good(fingers crossed) this weekend I'm going to attempt a prop hang.

I say attempt cos I've already done it in the garden.
Very Happy


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Post  John Goddard Fri Feb 08, 2013 8:35 am

Make of this what you will...

Ran same tank, same fuel, same (give or take 5 minutes) day.

Bernie Yellow wobblemeister 5x3 20500
Cox black 5x3 19870
Travelling prop 6X3 Zinger 13700


For some reason my Extreme much prefers Bernies Yellow Peril
in it's present state of tune.
It really doesn't like the Zinger 6x3

I've found that the stock Cox 5x3 is 4.2 grams whilst the Wobblemeister is a svelte >4.1 grams.
It's faster and you can hear it's faster.
Not only that, it pulls much harder too which again I'll attempt to demonstrate tomorrow at the field.

So to recap it's not because the tach is out or because the prop is the wrong colour or Saturn is ascending in the seventh house.......
It's just lighter and more efficient much like a Graupner G sonic 16X8 is a much better prop than an APC
16x6 on a YS110 but that's another story.
Very Happy
I think if you want a high reving prop better start looking at the Bernies yellow thing.
lol!

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Dragon Extreme tached at last Pictur11

PPS
Zinger 6x3 weighs 4.4 grams
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Post  Cribbs74 Fri Feb 08, 2013 9:20 am

I'll re-engage with the yeller props, problem is I had a tough time balancing them. I can say they do take a lot of abuse.

Ron
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Post  pkrankow Fri Feb 08, 2013 9:52 am

I love bashing with the yellow rubber duckies but I think they flatten a little when they are run up so the actual pitch is reduced some. I know they don't pull as good as other props of the same designation, but they pull well enough that it is worth using them, especially if they are going to see dirt regularly and repeatedly.

Phil
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Post  John Goddard Fri Feb 08, 2013 9:54 am

I think I hit it lucky with this one Ron.
It's perfectly balanced and the hole's even in the right place....
lol!
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Post  Dizzyman2011 Fri Feb 08, 2013 11:59 am

Tuning an engine is like dating a woman
the more you put in
the more they put out
Nice result John good readings
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Dragon Extreme tached at last Empty Could you try an APC 5.7 X 3

Post  buzzallnight Fri Feb 08, 2013 7:46 pm

Could you try an APC 5.7 X 3

these are very good props
my COX engines like them on SIG 25 percent

zinger props are blocks of wood

try a top flight wood 5 X 3
and you will see a difference
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Dragon Extreme tached at last Empty Could you try an APC 5.7 X 3

Post  buzzallnight Fri Feb 08, 2013 7:49 pm

Could you try an APC 5.7 X 3

these are very good props
my COX engines like them on SIG 25 percent

zinger props are blocks of wood

try a top flight wood 5 X 3
and you will see a difference
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Dragon Extreme tached at last Empty Soo, What Prop would you recommend??

Post  Jenuine Motor Sat Jul 07, 2018 6:34 pm

Surfer_kris wrote:Nice numbers, but isn't it the wrong prop, fuel and tach for the race?   lol!

I have a couple of dragon fly's, and I notice that they are a Very afordable engine, but has it "Aquardness" to it appearance and mounting. Nice to see a Dragon fly being re-worker/Put through the paces.
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