My Twin Killer Bee's ....

WV. FLYGUY wrote:Thought I'd share my Killer Bee's with the forum ... Here they are .......

You can see them very well, thank you for sharing the photo, I hope that next month you will be part of the ten photos exposed!

MauricioB wrote:

WV. FLYGUY wrote:Thought I'd share my Killer Bee's with the forum ... Here they are .......

You can see them very well, thank you for sharing the photo, I hope that next month you will be part of the ten photos exposed!

Thanks very much. I appreciate it.

Oh yes, you’ll have to keep an eye out for the “Submit your picture” of Engine of the Month. These will bee a great entry!

Nothin better to hear than two twins revin up in sync on a model airplane. Do you have plans for theses two? Mine and a few others here favorite is the P-38.

Marleysky wrote:Oh yes, you’ll have to keep an eye out for the “Submit your picture” of Engine of the Month. These will bee a great entry!

Nothin better to hear than two twins revin up in sync on a model airplane.  Do you have plans for theses two?  Mine and a few others here favorite is the P-38.

I just have collected these and they are never ran. I should fire them up just to hear run. I like the .049 and Tee Dee .51 to fly on control line. But you never know I might just put these to work. I love the Cox Pee Wee .020's also. I have several of them. Thanks for your reply and have a great evening.

WV. FLYGUY wrote:

Marleysky wrote:Oh yes, you’ll have to keep an eye out for the “Submit your picture” of Engine of the Month. These will bee a great entry!

Nothin better to hear than two twins revin up in sync on a model airplane.  Do you have plans for theses two?  Mine and a few others here favorite is the P-38.

I just have collected these and they are never ran. I should fire them up just to hear run. I like the .049 and Tee Dee .51 to fly on control line. But you never know I might just put these to work. I love the Cox Pee Wee .020's also. I have several of them. Thanks for your reply and have a great evening.

If you like the Pee Wee .020 I invite you to watch this video and I hope you like it!
https://www.coxengineforum.com/t11313-bank-of-engine-parts-cox-and-no-cox-exchange-trade-arrangement#143816

Are those engines really killer bees, they look a bit more like the spook engines to me?

Still nice looking engines though.

Surfer_kris wrote:Are those engines really killer bees, they look a bit more like the spook engines to me?

Still nice looking engines though.

Spook had the alloy backplate.  Killer Bee should have the red "horseshoe" backplate, or black on the later Estes ones.  A true Killer Bee should have SPI so the mufflers would seriously inhibit their performance.  They just look like standard #290 Product engines to me.  Not wanting to throw cold water

Surfer_kris wrote:Are those engines really killer bees, they look a bit more like the spook engines to me?

Still nice looking engines though.

Maybe so I bought them a long time ago and actually just got into researching them. They are not a standard .051 as here is what I found out in my reserch ....

1996 Killer Bee 051 (Cat#360 - Manufactured 1996)
The Killer Bee 051 existed so that modellers could fly the same plane in two competition classes (i.e. A and 1/2A) simply by changing the engine. This engine has exactly the same performance as the 049. There is a legend that two thin lines (or grooves) in the piston skirt are for positive identification but this is incorrect. The grooves were intentionally designed to bleed off just enough power so that the 4% increase in displacement does not necessitate trim changes to a free flight model when switching the model from an 049 to the 051 to fly in the higher "A" class.[15] The benefit of the grooves as a visual identifier was accidental.

I have not took them down to see if these have the two thin lines on the piston. But the compression is without a doubt different than a standard .049 engine,

1/2A Nut wrote:Greenie for sharing with us thank you

You are quite welcome. Wasn't trying to show them off just tryed to get them on the picture of the month and got it in the wrong place I believe anyway.

Oldenginerod wrote:

Surfer_kris wrote:Are those engines really killer bees, they look a bit more like the spook engines to me?

Still nice looking engines though.

Spook had the alloy backplate.  Killer Bee should have the red "horseshoe" backplate, or black on the later Estes ones.  A true Killer Bee should have SPI so the mufflers would seriously inhibit their performance.  They just look like standard #290 Product engines to me.  Not wanting to throw cold water

You are not throwing cold water whatsoever. I'm glad to get input as to what they really are. I like finding out the varibles on Cox engines. Plus I don't want to say I've got something that is not right also. Thanks for your thoughts.

WV. FLYGUY wrote:

Oldenginerod wrote:

Surfer_kris wrote:Are those engines really killer bees, they look a bit more like the spook engines to me?

Still nice looking engines though.

Spook had the alloy backplate.  Killer Bee should have the red "horseshoe" backplate, or black on the later Estes ones.  A true Killer Bee should have SPI so the mufflers would seriously inhibit their performance.  They just look like standard #290 Product engines to me.  Not wanting to throw cold water

You are not throwing cold water whatsoever. I'm glad to get input as to what they really are. I like finding out the varibles on Cox engines. Plus I don't want to say I've got something that is not right also. Thanks for your thoughts.

Actually the black backplates on the Killer Bees designated a .049 displacement as the red were .051 at least thats the way I understand, from my readings.

The nice thing about those "postage-stamp" reed-valve carb/back-plates is their fine-threaded needle valve assemblies! If you ever decide to try running a "high-pressure"/bladder-feed fuel-delivery on either of those engines; the fine-thread needle is MUCH easier to tune. Are there the original-style "Copper" star-shaped reeds installed in them? I personally prefer those reeds.. but many people swap them out for the Mylar-reed due either to necessity or that the Mylar reed is claimed to be more resistant to "float" at high-rpms.

Mounting that postage-stamp back-plate requires a little ingenuity. Goldberg models used to make an adapter mount for them.. and you can still find them.

Alternately.... you can make a small pair of sheet-metal mounting-plates with 90 degree "Z-bends" without having to make any modifications to your engines. This will allow you to radially mount the engines to a firewall for a bench-run.. or otherwise. Use thin (.020") stock that is 3/4" (.750") wide. Cut two pieces 3/4" long. It's easy.. the two bends are 1/4" apart. Drill the case-holes 17/32" on-center. A rat-tail file is used to cut a relief for the air-intake.

These I made from .060"aluminum.. but steel (something like the "banding" used to strap a shipping-pallet) might be easier to source.. and aluminum can develop stress-cracks when bending a tight 90-degree angle.  






Running mufflers will bog-down those engines.. but I can understand that you may be bound to noise-restrictions. I personally would forego the mufflers.. until it becomes an issue. If that happens; I guess that you'll have to use them, but if you're running them at a remote-location; run them without a muffler.

Sig Manufacturing Co's. 1/2A "Champion" 25 or 35 (% nitro) is GREAT fuel to run in these engines. It has the proper balance/percentage of castor-oil/synthetic-oil to lubricate the piston/rod ball/socket joint; "in particular"...which is thought to be crucial for the longevity of Cox engines.

Your choice of aero-propellers depends greatly on your "use" for the engine. Be sure to check/balance on any of them before running. A 5" diameter 3" pitch is a good "starting-point". The Cox .049 reed-valve engine in "stock-form" will like this propeller.

I only mention these things because we have not communicated too much. CEF is my favorite place! I hope that it will become "your" favorite place too!

1/2A Nut wrote:Here is my .049 Killer Bee / Made date: May 31st 1995  

Very very nice thanks for sharing. I guess mine are standard Cox .049's as mine does not look like yours. I was confused about what they looked like. Thanks for sharing the real McCoys.

1/2A Nut wrote:Here is my .049 Killer Bee / Made date: May 31st 1995  

Very nice to say the least. Thank you very much for sharing......

Gotta love that Scream !! Thanks for sharing your Bees WV.FLYGUY They look nice were there if not Killers

I just built this one up out of parts, couldn't get it over 18K using my benchmark 5/3 prop and 25% N.
Back to the bench, change cyl. and open up intake a little more.
I seem to have more vibration with KB cranks under 20K, do you find that also? Could be my props, I can't balance a prop worth a crap.

crankbndr wrote:I just built this one up out of parts, couldn't get it over 18K using my benchmark 5/3 prop and 25% N.
Back to the bench, change cyl. and open up intake a little more.
I seem to have more vibration with KB cranks under 20K, do you find that also? Could be my props, I can't balance a prop worth a crap.

Very nice engine and great job. Thanks for sharing ....

Doug, I would think that running the 8cc back-end/tank will amplify any inherent vibration. The rotational-mass is further away from the engine-mount as opposed to running a 5cc tank or a product backplate/carb. We naturally want our propellers as close to being balanced as possible.. but there's only so much we can do; where the engine-mounting is at the extreme rear on the reed-valve engines. You'd likely see an increase in rpm's by swapping to a shorter back-end because of this.. but unfortunately; there are other variables involved in a test. You could drill-out the air-intake of a 5cc tank and backplate to the same dimensions.. but the length of the venturi-tube is shorter.. and the "reed" might not fit and flow the same as the one in the 8cc tank.

I believe that the "Killer Bee's" high-performance is partly due to its short back-end, keeping vibration to a minimum.

Check also the aftermarket KB crank...there was a bunch of them with the shaft machined not coaxial with the splined shaft end and thus throwing the prop out of center. These shafts typically had a small hole drilled in their center, like this one:

The KB shafts without the hole in the center, sold by Bernie and Matt are OK though. I swapped my ones with those of Bernie and the vibe was instantly gone.