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

Mauricio, your engine does seem to have the Killer Bee cylinder. It has the narrow exhaust ports AND sub-piston induction (SPI), and the lower ports are wider.

Can you see the by-pass ports inside the cylinder? I am not sure how they are supposed to look as I don't have a Killer Bee in my collection yet.

The backplate seems correct, there is no steel mesh on the intake.

I think it's a very nice looking engine, and the "correct" Killer Bee crankshaft is available as a reproduction, so you can make it "complete" if you want.

I have the Estes version of the Killer Bee which is not anodized gold. In addition, the red backplate to my knowledge was one indicator that the engine was to be .051 vs .049. However, the needle valve on your engine is not correct for the early Cox version as it has a knob and not the yellowish extension on it. The .051 piston for the Killer Bee had two grooves on it vs the Tee Dee which had one. The backplate also offered a larger intake opening vs stock backplates. The crank is what appears to be stock. Looking at your example though, I can only say you have a wonderful looking example and while some of the components may not be the early version, I certainly wouldn't be bashful in showing that one off. It looks great and I'm certain it will perform equally as well.

KariFS wrote:Mauricio, your engine does seem to have the Killer Bee cylinder. It has the narrow exhaust ports AND sub-piston induction (SPI), and the lower ports are wider.

Can you see the by-pass ports inside the cylinder? I am not sure how they are supposed to look as I don't have a Killer Bee in my collection yet.

The backplate seems correct, there is no steel mesh on the intake.

I think it's a very nice looking engine, and the "correct" Killer Bee crankshaft is available as a reproduction, so you can make it "complete" if you want.

Many thanks Kari, here I put a picture of the inside of the cylinder, what do you think?
If I use this crankshaft, is there any appreciable difference with the alternative "pear" crankshaft?

Ken Cook wrote:         I have the Estes version of the Killer Bee which is not anodized gold. In addition, the red backplate to my knowledge was one indicator that the engine was to be .051 vs .049. However, the needle valve on your engine is not correct for the early Cox version as it has a knob and not the yellowish extension on it. The .051 piston for the Killer Bee had two grooves on it vs the Tee Dee which had one. The backplate also offered a larger intake opening vs stock backplates. The crank is what appears to be stock. Looking at your example though, I can only say you have a wonderful looking example and while some of the components may not be the early version, I certainly wouldn't be bashful in showing that one off. It looks great and I'm certain it will perform equally as well.

Many thanks Ken for the information, here I put a photo of the piston, to be "common" does not have two slots, what do you think ??
I also leave the question I asked kari, what can you tell me?
If I use this crankshaft, is there any appreciable difference with the alternative "pear" crankshaft?

The idea behind the pear shaped crank is that it's lighter. Lighter mass is easier to turn thus more rpm's. I personally feel that stock Cox crankshafts are superior equally that is until they break. I have broken a few of them but not consistently. I have to say that engine just is good looking. I think your going to find it to be quite a reliable and powerful engine. Ken

Ken Cook wrote:          The idea behind the pear shaped crank is that it's lighter. Lighter mass is easier to turn thus more rpm's. I personally feel that stock Cox crankshafts are superior equally that is until they break. I have broken a few of them but not consistently. I have to say that engine just is good looking. I think your going to find it to be quite a reliable and powerful engine. Ken

Thank you Kent for giving me your opinion!

start the Killer Bee 051 today.
Start with a 5 x 3 propeller, open and fat marching needle.
Use about 4 tanks of about 100 cc, march ten, march ten, and so on.
Fuel 20-5-75 Ricino-Nitro-Methanol
Also fit a throttle ring, as I plan to use it for r / c.
I like how this engine runs !!



after that march, probe other propellers tuning the engine, very good response! ...and the night was over.

Nice to see the engine running my friend! The Cox 5 x 3 as you know; is a good "all-around" propeller for the .049 reed (flapper)-valve engine. The company "APC" makes a 4.75" x 4" propeller.. that you may want to try. It is solid (rigid) true to pitch. The center (hub) hole requires a bushing for the Cox 5-40 propeller-screw. A short-length piece of soft (silicone) fuel-line can be used for this. Maybe you already have experience with this propeller?





I have a theory regarding crankshaft "weight" (rotational-mass) with regard to throttling a model engine. More "mass" (weight) enables the engine to stay running at slow-speed.. because of "inertia" working against compression. The transition from "slow to fast" will be adversely affected.. but this is of little concern with an airplane engine.

I have seen more favorable/consistent low-idle (slow-speed) results when installing a "fly-weight" (flywheel) in the form of a small precision steel flat-washer with the propeller. The washer requires a 1/8" (.125"/3.18mm) center hole for the Cox .049's 5-40 propeller-screw to balance and spin "true".

It's FUN to experiment with throttling these engines. I have achieved sustained sub-3K rpm operation with a Cox 6" x 3" propeller on a stock Cox Babe Bee engine.. "without" any weighting of the crankshaft. A muffler helps to keep the head-temperature (glow-plug) HOT.. to sustain combustion at low-speeds while in the air.

Your engine is similar in configuration; to the one I entered in the CEF "tach-race" this year.



Ron Cribbs was able to extract 19,560 rpm from it.. with the APC 4.75" x 4" propeller. The engine cylinder was a quasi Tee Dee-ported one from Cox International.. equipped with a Tee Dee (high-compression) glow-head, using one head-gasket. Fuel was high-nitro 30+%.

Your Killer Bee engine would like to "taste" fuel with more nitro. I would make an inquiry to "Sig Manufacturing" in the U.S.A. (Montezuma, IA) for a small (pint) bottle of their "Champion 35" 1/2A fuel.. which has plenty of castor (ricino) to protect your engine. A small bottle may be exempt from air-freight restrictions.

http://www.sigmfg.com/cgi-bin/dpsmart.exe/IndexFieldEquipmentF.html?E+Sig

I always thought the original Cox Killer Bee had a diesel crankshaft, but I could be mistaken, so I'll defer to Ken on that. The cylinder is certainly a KB.

While tuning for tach races I always get the fastest runs from a stock babe Bee crank over the diesel crank. I'd say yours can most certainly be called a Killer Bee with no doubts. Very nice engine.
Rusty

[quote="roddie"] Nice to see the engine running my friend! The Cox 5 x 3 as you know; is a good "all-around" propeller for the .049 reed (flapper)-valve engine. The company "APC" makes a 4.75" x 4" propeller.. that you may want to try. It is solid (rigid) true to pitch. The center (hub) hole requires a bushing for the Cox 5-40 propeller-screw. A short-length piece of soft (silicone) fuel-line can be used for this. Maybe you already have experience with this propeller?

........quote]

Roddie,

I once bought a propeller which was very much similar in appearence and package to this APC, but it was exclusively for electric motor application, the paper tag stapled to the plastic bag had a warning on that. (You may want to see the backside of that white flip stapled to yours)

One reason why the bushing was also needed for that was the apparently larger electric motor shaft diameter for a 4.5....5.5 inch prop than the propeller screw of a COX engine. I read once - but do not necessarily believe - that the composite propellers are prone to fatigue-breaking under the cyclic load of an internal combustion engine.

I use the black nylon propellers even though their pitch might slightly change at high rpm-s, and never has seen one break in operation.

Hi Andras, The APC 4.75" x 4" prop packaging does not have that warning. I have however seen it on larger diameter APC propeller packages. The APC 4.75" x 4" propeller was used for this year's CEF "tach-race" and was also widely used by several of the CEF reed-speed contestants. I'm not implying that it's a "safe" propeller.. just that there is no warning by APC against use with internal-combustion engines.

roddie wrote: Nice to see the engine running my friend! The Cox 5 x 3 as you know; is a good "all-around" propeller for the .049 reed (flapper)-valve engine. The company "APC" makes a 4.75" x 4" propeller.. that you may want to try. It is solid (rigid) true to pitch. The center (hub) hole requires a bushing for the Cox 5-40 propeller-screw. A short-length piece of soft (silicone) fuel-line can be used for this. Maybe you already have experience with this propeller?





I have a theory regarding crankshaft "weight" (rotational-mass) with regard to throttling a model engine. More "mass" (weight) enables the engine to stay running at slow-speed.. because of "inertia" working against compression. The transition from "slow to fast" will be adversely affected.. but this is of little concern with an airplane engine.

I have seen more favorable/consistent low-idle (slow-speed) results when installing a "fly-weight" (flywheel) in the form of a small precision steel flat-washer with the propeller. The washer requires a 1/8" (.125"/3.18mm) center hole for the Cox .049's 5-40 propeller-screw to balance and spin "true".

It's FUN to experiment with throttling these engines. I have achieved sustained sub-3K rpm operation with a Cox 6" x 3" propeller on a stock Cox Babe Bee engine.. "without" any weighting of the crankshaft. A muffler helps to keep the head-temperature (glow-plug) HOT.. to sustain combustion at low-speeds while in the air.

Your engine is similar in configuration; to the one I entered in the CEF "tach-race" this year.



Ron Cribbs was able to extract 19,560 rpm from it.. with the APC 4.75" x 4" propeller. The engine cylinder was a quasi Tee Dee-ported one from Cox International.. equipped with a Tee Dee (high-compression) glow-head, using one head-gasket. Fuel was high-nitro 30+%.

Your Killer Bee engine would like to "taste" fuel with more nitro. I would make an inquiry to "Sig Manufacturing" in the U.S.A. (Montezuma, IA) for a small (pint) bottle of their "Champion 35" 1/2A fuel.. which has plenty of castor (ricino) to protect your engine. A small bottle may be exempt from air-freight restrictions.

http://www.sigmfg.com/cgi-bin/dpsmart.exe/IndexFieldEquipmentF.html?E+Sig

Roddie, very interesting all his contribution! ... I emphasize his comment on the slow speed of the engine favored by a round crankshaft and not of the pear type, I am really happy to know that since I am very interested that the engine achieves low RPM, that allows me to "play" to land with the engine running.
Maybe it does not have a reaction as explosive as with the pear-type crankshaft, but as you comment, in the model (model) in my case, it is not important.
Another interesting fact is the subject of an auxiliary washer of use like "flywheel of inertia".
Yes my friend, I also tested an APC propeller (high speed) the smallest I got here is 5.7 inches in diameter and I actually use a piece of neoprene hose to center with the screw. With that propeller and the same fuel achieve about 15000 rpm. Thanks in advance for the advice of using neoprene to the center of the propeller.
I would like to compare the minimum and maximum returns between a Medallion .049 and a Killer Bee .051, and as soon as I have time I will compare them!
Thanks for all the Roddie tips, they are much appreciated! ....
By the way, which model do you plan to use your Killer Bee ???? ...

I forgot! ... I have read many times the term 3K or 4K ..mmm meaning: K ??
Excuse my ignorance!

RknRusty wrote:I always thought the original Cox Killer Bee had a diesel crankshaft, but I could be mistaken, so I'll defer to Ken on that. The cylinder is certainly a KB.

While tuning for tach races I always get the fastest runs from a stock babe Bee crank over the diesel crank. I'd say yours can most certainly be called a Killer Bee with no doubts. Very nice engine.
Rusty

Thanks Rusty for giving his opinion, I'm glad to know he's a real killer bee!
I think it has a lot of power ... at least stop in the first gear that has a lot of energy!

balogh wrote:

roddie wrote: Nice to see the engine running my friend! The Cox 5 x 3 as you know; is a good "all-around" propeller for the .049 reed (flapper)-valve engine. The company "APC" makes a 4.75" x 4" propeller.. that you may want to try. It is solid (rigid) true to pitch. The center (hub) hole requires a bushing for the Cox 5-40 propeller-screw. A short-length piece of soft (silicone) fuel-line can be used for this. Maybe you already have experience with this propeller?

........quote]

Roddie,

I once bought a propeller which was very much similar in appearence and package to this APC, but it was exclusively for electric motor application, the paper tag stapled to the plastic bag had a warning on that. (You may want to see the backside of that white flip stapled to yours)

One reason why the bushing was also needed for that was the apparently larger electric motor shaft diameter for a 4.5....5.5 inch prop than the propeller screw of a COX engine. I read once - but do not necessarily believe - that the composite propellers are prone to fatigue-breaking under the cyclic load of an internal combustion engine.

I use the black nylon propellers even though their pitch might slightly change at high rpm-s, and never has seen one break in operation.

Thanks for that detail András !, when I asked for the APC helix, in my case a 5.7, I made sure it was for glow, in my case, so I was sold, not suitable for electric, but to glow!

MauricioB wrote:
I forgot! ... I have read many times the term 3K or 4K ..mmm meaning: K ??

The "K" means "kilo" (or thousand), so in this case 3K = 3000 rpm.

Nice to see your Killer Bee running. I am also very interested in all the throttling tests you, Andras, Roddie and many others conduct! Once I (or if I ever) learn to fly an R/C plane properly, a small sports model or an old-timer with a Cox engine will definitely be on the project list

I own a real Killer Bee .049 the inside of the piston is copper coated and the piston / rod weight is 2.9g
Less than a standard piston 3.4g. The piston skirt is thinner too, note the polished walls on the inside of
the cylinder. The crank flywheel is lighter and has a drilled out crank pin. It comes with the fine thread
NV with nyrod extension. Black back plate .049 / Red for the .051 which had the ring around
the bottom of the piston skirt for designation. The real Killer Bee is made for screaming rpm and has
no reason to do anything else. Note I changed out the spinner and bolt to suit the APC prop the real
one is to the right first pic.



Mauricio your engine was the year they stopped making the high performance crank and light weight piston
the loss in rpm was notable, I am not sure what month the change was made. You many not have the fine
thread NV rather a 72tpi needle instead of the 128tpi . The cylinder was no longer matched and polished
they just started selling off what was left on hand as is. Still you have the larger intake that is helpful and
aggressive porting. You may have a red back plate but the cylinder / piston could be a .049

KariFS wrote:

MauricioB wrote:
I forgot! ... I have read many times the term 3K or 4K ..mmm meaning: K ??

The "K" means "kilo" (or thousand), so in this case 3K = 3000 rpm.

Nice to see your Killer Bee running. I am also very interested in all the throttling tests you, Andras, Roddie and many others conduct! Once I (or if I ever) learn to fly an R/C plane properly, a small sports model or an old-timer with a Cox engine will definitely be on the project list

thanks Kari for teaching me the term K, the truth did not know exactly how it was used !.
The first contact I made for the subject of regulation of march was with Roddie, through Youtube, I answered all my doubts, then, with the data of Roddie, I started to work on an accessory similar to the commercial, made it work, You can try it too. This system still does not use it in any model, but in the experience (that you can see in the video) works perfect!



It is a very nice senzación (at least for me) fly RC, senzacion of freedom and fly over any terrain or landscape, it generates me much pleasure, turn when it comes to a speed model, make past rapping and acrobatic maneuvers generates an incredible adrenaline, beautiful senzación!
Go ahead, I'll be watching your model project, when you start it!

1/2A Nut wrote:I own a real Killer Bee .049 the inside of the piston is copper coated and the piston / rod weight is 2.9g
Less than a standard piston 3.4g. The piston skirt is thinner too, note the polished walls on the inside of
the cylinder. The crank flywheel is lighter and has a drilled out crank pin. It comes with the fine thread
NV with nyrod extension. Black back plate .049 / Red for the .051 which had the ring around
the bottom of the piston skirt for designation. The real Killer Bee is made for screaming rpm and has
no reason to do anything else. Note I changed out the spinner and bolt to suit the APC prop the real
one is to the right first pic.



Mauricio your engine was the year they stopped making the high performance crank and light weight piston
the loss in rpm was notable, I am not sure what month the change was made. You many not have the fine
thread NV rather a 72tpi needle instead of the 128tpi . The cylinder was no longer matched and polished
they just started selling off what was left on hand as is. Still you have the larger intake that is helpful and
aggressive porting. You may have a red back plate but the cylinder / piston could be a .049

Thanks 1 / 2A Nut!! , for the detailed information and photos .... it means that the true bee is the one that you have, right? and the one that I have was sold as Killer Bee but it only has some parts, that is to say that from factory it was sold then in two versions.
Could I then call his Killer Bee Special? and Mia Killer Bee? how is it that from the origin of manufacture or armed they called two different engines by the same name? ... I know that Cox was sold several times, I understand that they took parts of Stock and armed some engines, but to differentiate them, add some additional term, Killer Bee Special or Killer Bee Version 1 ..... thing that can be differentiated and so call them for what they really are, two engines with different details. Share what I think ??

Hi Mauricio,

In my opinion, especially the later owners of COX, Estes included, wanted to capitalize on the fame and reputation of older COX engines made in the heyday of COX, and sold engines under the same names, assembled in similar configuration, but from less sophisticated parts, to retain profits earned on the older versions....Sure Start cylinders, normal pistons and cranks.

Nevertheless, because the porting of the cylinder on your engine as well as the backplate are like in the older Killer Bees, I expect this engine is an excellent runner. Did you tach it?

I home-assembled similar configurations (my Lil Roughneck has one on it, called TeeDeeReedie because of its cylinder) and it turns the black 5x4 (=4,8x4) prop of Bernie at near 20k i.e.while the TeeDee 051 turns it around 21+k, i.e. less than 10% faster, if you remember my thread a few days ago.

Yes Mauricio,
There is only 1 true build spec for the .049 and .051 Killer Bee
The low weight piston and crank make a big difference.
128 TPI NV lets you milk the top end rpm.
The polished inside of the cylinder minimizes break in wear for
best top end rpm.

balogh wrote:Hi Mauricio,

In my opinion, especially the later owners of COX, Estes included, wanted to capitalize on the fame and reputation of older COX engines made in the heyday of COX, and sold engines under the same names,  assembled in similar configuration, but from less sophisticated parts, to retain profits earned on the older versions....Sure Start cylinders, normal pistons and cranks.

Nevertheless, because the porting of the cylinder on your engine as well as the backplate are like in the older Killer Bees, I expect this engine is an excellent runner. Did you tach it?

I home-assembled similar configurations (my Lil Roughneck has one on it, called TeeDeeReedie because of its cylinder) and it turns the black 5x4 (=4,8x4) prop of Bernie at near 20k i.e.while the  TeeDee 051 turns it around 21+k, i.e. less than 10% faster, if you remember my thread a few days ago.

Hello friend András ... I am nobody to talk about the subject, that is to say, only a user of Cox engines ... I am thinking and I am very right in my procedure, therefore I must tell you all the truth of what I think ; If in truth whoever was the later owner of Cox, used parts of engines calling them by a name that does not correspond, is unsettling and leaves me speechless.
I'm happy with this engine, but I really think it should be called different. At least Cox Killer Bee Mini ... as your friend Brad says, it is very likely that it is not a .051 and that is then a .049 and therefore, I do not know what engine I have .... if I backed myself in its seller of factory, this is a Killer Bee .051 and if I compare it with original Cox fabrications, it is not

András, I can not translate this prayer of yours:
Did you tach it?
Can you write it any other way? I can not understand your question, thank you!

1/2A Nut wrote:Yes Mauricio,
There is only 1 true build spec for the .049 and .051 Killer Bee
The low weight piston and crank make a big difference.
128 TPI NV lets you milk the top end rpm.
The polished inside of the cylinder minimizes break in wear for
best top end rpm.

and what motor have I sold then? as it is called?

Thanks Mauricio, and sorry to have caused you frustration. We know that - thanks also to the inter-changeability of parts - even COX often combined parts in the same engine type and this is why a plethora of various engine combinations exists with thin wall, thick wall, stepped wall cylinders that are either tapered or not, anodized or un-anodized parts, plastic and aluminum carbs. etc.

The "tach" is an Americanism I learned here on CEF, meaning to measure the engine rpm with a tachometer...