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Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  Surfer_kris on Fri Oct 20, 2017 2:54 am

I'm well aware of the Carnot cycle, but that is not the issue/problem with the regular plugs.

It feels like history is repeating it self. We went over this about ten years ago on RCU: The great glow plug run off

In short it is the threads of the regular plugs that are the problem. The seal with a copper gasket is simply in the wrong place, and the threads of the plug are actually a part of the combustion chamber.

If these threads are sealed, and the compression ratio is set-up right, the plug can almost match the proper glow heads (OEM, Nelson and Turbo etc.)
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Fri Oct 20, 2017 3:39 am

Yes this vid will be the best way to put the two well known plugs into prospective.

Design elements in play here, compression via volume or sustained low leak threads.
The various uses of the metals in this case primaraly all aluminum vs a steel plug cased
in an aluminum shell. The Carnot efficiency variables with a simple steel cylinder /case
effecting the adiabatic lapse rates too. Mind you the higher nitro acts as a coolant thus
improves the theoretical carnot maximums with the help of some good ole castor.
Is why you see a non SPI engine with a muffler being use to improve consistency between
the two test plugs up for this event. Should help stabilize the adiabatic laps rates leaving
only plug design bleeding their variance values for all who view the vid.

Note I am also using a 4.2x4 prop there will be no laboring of the engine to cause issues. Speaking
of front induction should also help to keep volumes constant with the fuel air mix being aspirated well
away from the heat source which includes an aluminum carb body to entice best possible readings.

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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  getback on Fri Oct 20, 2017 9:30 am

Thanks Brad for the info when $$$ allows i will bee talking to Larry , i can see the difference in the pics. of the seal mainly of the Galbreath compared to the Cox Hi comp. hd. Be looking for the vid when time is right . Small Cox Logo This Site Rocks!
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  MauricioB on Fri Oct 20, 2017 12:55 pm

1/2A Nut wrote:
Instead of typed in unverifiable numbers and claims, how about a video!


Both high performance plugs are in good shape same engine / prop per this pic.  
Will film the event Fri. using 25% Nitro / 20% castor.

Horsing Around






Interesting Brad, I'll be watching the video! Smile
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Fri Oct 20, 2017 3:33 pm

New engine so got to peak and back off just a hair from there.
NV was not touch swapped out plugs within a minute, restarted the engine
got close to an equal run time temp then shut it down zoomed in on the
cox plug to show it's type:







10/20/2017
APC 4.2x4 / 2 gaskets / 25%

1st run: Galbreath / Nelson: 21,479
+ 485 rpm more static good for much more unloaded in the air.

2nd run: Cox High Comp: 20,994

Will run it rich for a bit more and add a pressure tap on the
muffler to find out what is possible with this RC version.
Hope to see 22.4k not near as noisy as a open exhaust TD.  
Will test with the HQ 5x4.5

Small Cox Logo
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  MauricioB on Fri Oct 20, 2017 10:30 pm

1/2A Nut wrote:New engine so got to peak and back off just a hair from there.
NV was not touch swapped out plugs within a minute, restarted the engine
got close to an equal run time temp then shut it down zoomed in on the
cox plug to show it's type:







10/20/2017
APC 4.2x4 / 2 gaskets / 25%

1st run: Galbreath / Nelson: 21,479
+ 485 rpm more static good for much more unloaded in the air.

2nd run: Cox High Comp: 20,994

Will run it rich for a bit more and add a pressure tap on the
muffler to find out what is possible with this RC version.
Hope to see 22.4k not near as noisy as a open exhaust TD.  
Will test with the HQ 5x4.5

Small Cox Logo

One or the other glow plug are going very well, I think there is little difference ... no?
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Fri Oct 20, 2017 10:55 pm

+ 485 rpm more with the Nelson head on a new old stock engine which
should equate to about 1,000 ish more rpm unloaded in the air over the cox plug.
Mind you this is +485 rpm against the all mighty Cox High Compression head that's
saying a lot.

With a 4" pitched prop about another 4 mph unloaded.  I was only able to set the
needle lean enough to get the engine steady, needs more rich run in time. Perhaps
next test should be a full NV peak per plug. Will make time to do that Saturday.
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  MauricioB on Fri Oct 20, 2017 11:03 pm

1/2A Nut wrote:+ 485 rpm more with the Nelson head on a new old stock engine which
should equate to about 1,000 ish more rpm unloaded in the air over the cox plug.
Mind you this is +485 rpm against the all mighty Cox High Compression head that's
saying a lot.

With a 4" pitched prop about another 4 mph unloaded.  I was only able to set the
needle lean enough to get the engine steady, needs more rich run in time. Perhaps
next test should be a full NV peak per plug. Will make time to do that Saturday.

is true, is an improvement, considering that you are comparing with a high compression Cox, is an improvement, no doubt!
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  Surfer_kris on Fri Oct 20, 2017 11:24 pm

How many head shims were used on the TD plug?
The Galbreath head has a higher compression ratio, so ideally one should optimise each head/plug with the number of shims too. Did the optimum needle setting change between the heads? That can be an indication of the difference in compression ratio.

I've heard that one can gain a bit on the TD plug by removing about a head shims worth of material from the TD plugs. So that is also something to try, and the mod can always be restored by adding an extra head shim later, if it doesn't give an improvement.

The power developed seems to be rather low, only 40-50W? Perhaps you are using a too small prop?
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Sat Oct 21, 2017 12:14 am

Each had 2 shims and the same NV setting.
Larry supplies 2 shims and makes comment in the note sent with
the parts. Typically I use one shim with small props up to 5in dia.
I was ok with 2 shims since this is a new engine being used for the
testing. I have upgraded the muffler with a pressure tap!

65.7w NV set just enough to start singing will do better / new engine.
The power out was not the concern during the testing in the long
run I do look forward to seeing what the engine can do. This is fun
stuff for me I enjoy testing these lil wonders.

Yes the smaller prop will always equal lower watts you need to be
up at 24.65k  rpm to hit 100w with the APC 4.2x4 a lager dia. prop
will bump up the watts better per the calc program. I used the small
prop to keep the duty load off the engine.

The test efforts should be with the plugs untouched as is. The shim
count should be the same too. Any preening / mods for more power is on
another level. This time will peak the needle per plug to give them
both individual chances to shine.

My observation:
Test 1 the engine was running bit more rich than test 2 cox plug was
closer to it's peak needle.

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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  MauricioB on Sat Oct 21, 2017 12:29 am

1/2A Nut wrote:Each had 2 shims and the same NV setting.
Larry supplies 2 shims and makes comment in the note sent with
the parts. Typically I use one shim with small props up to 5in dia.
I was ok with 2 shims since this is a new engine being used for the
testing. I have upgraded the muffler with a pressure tap!

65.7w NV set just enough to start singing will do better / new engine.
The power out was not the concern during the testing in the long
run I do look forward to seeing what the engine can do. This is fun
stuff for me I enjoy testing these lil wonders.

Yes the smaller prop will always equal lower watts you need to be
up at 24.65k  rpm to hit 100w with the APC 4.2x4 a lager dia. prop
will bump up the watts better per the calc program. I used the small
prop to keep the duty load off the engine.

The test efforts should be with the plugs untouched as is. The shim
count should be the same too. Any preening / mods for more power is on
another level. This time will peak the needle per plug to give them
both individual chances to shine.

My observation:
Test 1 the engine was running bit more rich than test 2 cox plug was
closer to it's peak needle.


Brad, I have a .09 with a carburetor and exhaust, always ask me: why do not you have a pressurizer? ... you've done this test, do you recommend putting a pressure in?

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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Sat Oct 21, 2017 12:50 am

Yes absolutely I have one on my TD .09 RC makes for steady fuel feed big plus.
You can unscrew the back portion of the muffler to tap the aluminum.

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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  MauricioB on Sat Oct 21, 2017 12:59 am

1/2A Nut wrote:Yes absolutely I have one on my TD .09 RC makes for steady fuel feed big plus.
You can unscrew the back portion of the muffler to tap the aluminum.


Thank you my friend! I wonder .... why not have it incorporated from the factory ?? Cox.
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Sat Oct 21, 2017 1:16 am

Because they have a tap on the carb body for pressure.

I bought some of these carbon 4x4.5 props they have
an undercambered airfoil for more lift made for drones, will
create good thrust and speed. 3.3g


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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  MauricioB on Sat Oct 21, 2017 1:30 am

1/2A Nut wrote:Because they have a tap on the carb body for pressure.

I bought some of these carbon 4x4.5 props they have
an undercambered airfoil for more lift made for drones, will
create good thrust and speed. 3.3g



how many possibilities there are there friend ... here I have a very large magnifying glass and when something ZAZ appears! !! "I do not let it slip!"
Judging by the photo on the left, the one you have on the scale is spinning or rotating from left to right right?
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  Surfer_kris on Sat Oct 21, 2017 1:44 am

1/2A Nut wrote:Each had 2 shims and the same NV setting.

Okey, then the difference in rpm numbers could be highly related to a difference in the compression ratios. The compression ratio is higher with the Galbreath head compared to the TD one.
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  Surfer_kris on Sat Oct 21, 2017 1:46 am

MauricioB wrote:

Thank you my friend! I wonder .... why not have it incorporated from the factory ?? Cox.

I've flown the 05RC a lot without pressure tap, it didn't need any. I think it mainly depends on how good the fuel draw is in the carb, and it is seems adequate as it is.

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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Sat Oct 21, 2017 2:01 am

Kris if you have a fast plane and pull up hard it sags the engine without pressure.
4 and 4.5 pitch props help make a Cox powered plane fast, baring low weight and size.
I have lots of vids with engines sagging as they pull up / even when on pressure. Would
be even worse without it.

Yes they come in packs of two one CCW / CW
I can use the CW for the Killer Bee. They have
more camber than the HQ props which really do
well for thrust and speed.

I made a mistake the prop is an APC 4.5x4 used in the test
Which is good news for the engine at least the numbers make
more sense noticed when I put the prop next to the 4x4.5 carbon:

TD .049 RC / Nelson Plug / APC 4.5x4 / 21,479 rpm
Best read static: 87.3w / 8.5oz thrust / 82 mph

Cox TD .049 RC / High Comp Plug / APC 4.5x4 / 20,994
Best read static:  81.3w / 8.1 oz thrust / 79. 5 mph

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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  Surfer_kris on Sat Oct 21, 2017 2:17 am

1/2A Nut wrote:Kris if you have a fast plane and pull up hard it sags the engine without pressure.
4 and 4.5 pitch props help make a Cox powered plane fast, baring low weight and size.
I have lots of vids with engines sagging as the pull up / even when on pressure. Would
be even worse without it.


I always fly with at least 4" pitch on the prop, the picture above is from the maiden and I started with a rubber ducky 6x3 for a more calm maiden flight. I have not had any problems in pull ups or vertical lines. Perhaps you tanks have been positioned too low?

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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Sat Oct 21, 2017 2:24 am

In my case it is because the NV is set for top end speed leaving less room for anything less.
Always within a few clicks of starving the engine.  I simply must have pressure when
ever possible always a plus. There really is no low or high point to work with always foam
the tanks off the bottom of the fuselage to avoid vibrations.  The planes are minimal in
design / size with the tank up close as possible to the carb.

You have a K&B .049 5 x 4 Propeller mounted on the engine in the pic.



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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  Surfer_kris on Sat Oct 21, 2017 2:34 am

1/2A Nut wrote:
Always within a few clicks of starving the engine.  I simply must have pressure when
ever possible always a plus. There really is no low or high point to work with always foam
the tanks off the bottom of the fuselage to avoid vibrations.  The planes are minimal in
design / size with the tank up close as possible to the carb.

You have a K&B .049 5 x 4 Propeller mounted on the engine in the pic.

You can rotate the engine, such that the cylinder is horizontal instead of vertical, that will lower the carb in relation to the fuel tank.

It should be the K&B 6x3 prop in the picture, if I remember correctly, I only used the 5x4 later. It deforms on a Norvel though and I will have to find something else...
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Sat Oct 21, 2017 2:40 am

I have a few of those props they are nice for what they are, I like the shape.
Yes good trick for getting the carb lower but I don't like laying down the cylinder
on these simple engines nor inverting them.

So did you catch the test was done with a APC 4.5x4?

Makes for more reasonable power out of the engine.

TD .049 RC / Nelson Plug / APC 4.5x4 / 21,479 rpm
Best read static: 87.3w / 8.5oz thrust / 82 mph

Cox TD .049 RC / High Comp Plug / APC 4.5x4 / 20,994
Best read static:  81.3w / 8.1 oz thrust / 79. 5 mph
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  Surfer_kris on Sat Oct 21, 2017 2:46 am

1/2A Nut wrote:

So did you catch the test was done with a APC 4.5x4?

Makes for more reasonable power out of the engine.

TD .049 RC / Nelson Plug / APC 4.5x4 / 21,479 rpm
Best read static: 87.3w / 8.5oz thrust / 82 mph

Cox TD .049 RC / High Comp Plug / APC 4.5x4 / 20,994
Best read static:  81.3w / 8.1 oz thrust / 79. 5 mph

Yes, that makes more sense now. Smile
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  1/2A Nut on Wed Nov 08, 2017 1:45 am

Hi Mauricio, did your Killer Bee crank show up in the mail yet?
It has been 26 days so far.


Tracking Number: LC957340045US

Not Trackable
USPS Tracking®️ is unavailable for this product for ARGENTINA.



Computer Issues  
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

Post  MauricioB on Wed Nov 08, 2017 6:41 am

1/2A Nut wrote:Hi Mauricio, did your Killer Bee crank show up in the mail yet?
It has been 26 days so far.


Tracking Number: LC957340045US

Not Trackable
USPS Tracking®️ is unavailable for this product for ARGENTINA.



Computer Issues  

Friend Brad, I'm still waiting, today I called the mail, (I have friends there), but they have no news. They tell me that the number you send me changes their number when they enter my country and they do not have information.
I'm calling the customer service center to see if they can tell me something.
I will be informing you as soon as I have news.
Did you receive my shipment?
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Re: Buy a Cox! ... but, what exactly do you buy?: KILLER BEE .051 1996

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