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Actual Killer Bee numbers from Cox?

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Actual Killer Bee numbers from Cox? Empty Actual Killer Bee numbers from Cox?

Post  batjac Thu Dec 29, 2022 2:58 pm

I am in the mood to do my own Killer Bee clone, and I've been looking for some official numbers from Cox on how it should run.  I've seen the instruction sheet from Cox for the Killer Bee, but it didn't include RPM numbers for different props.  When I search for KB numbers, I see people doing their own clones and running smaller props for max RPM.  But I want to see what I can get on a Cox competition grey 6x3 prop, and how that compares to a real Killer bee.

Does any one have the original Cox numbers?

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Post  706jim Thu Dec 29, 2022 5:21 pm

763

(Actually I have no idea)
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Post  1/2A Nut Thu Dec 29, 2022 6:12 pm

I have data with a 5 x 4.5 similar loading ish to a 6x3 - turbo plug adapter used.

1991 Killer Bee .049 / 5x4.5 / 19,379 rpm
Static power per thrust calc. 10.6oz thrust / 83mph / .147hp / 110w


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Post  batjac Fri Dec 30, 2022 2:49 pm

1/2A Nut wrote:I have data with a 5 x 4.5 similar loading ish to a 6x3 - turbo plug adapter used.
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That's the thing. Lots of people have personal experience and data, but I'm looking for what Cox said that the KB would do, if Cox ever put out any numbers. I want to use the official numbers as a reference for what I come up with.

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Post  1/2A Nut Fri Dec 30, 2022 8:51 pm

The Killer Bee manual dated 1995 does not state what the engine can do per prop brand / size.
It does say to prop the engine at 22k static or less for longer life.
At the time of print it does state a few suitable props to include the APC 5.5x2 / Cox 5x3.5 / Cox 6x3

Does state warranty is voided if:
all synthetic oil is used
less than 10% castor in oil package
total oil package less then 20%
diesel head conversions
shaved heads
improper prop size
more than 50% nitro

A plane that is:
draggy
large size
heavy weight
has heavy line drag- if CL
- can wear out the engine faster even if kept 22k max static.

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Post  batjac Sat Dec 31, 2022 2:30 am

1/2A Nut wrote:The Killer Bee manual dated 1995 does not state what the engine can do per prop brand / size.
It does say to prop the engine at 22k static or less for longer life.
At the time of print it does state a few suitable props to include the APC 5.5x2 / Cox 5x3.5 / Cox 6x3
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Yeah, I read those numbers from the data sheet.  I was just hoping someone had seen something concrete in some other Cox literature.  Lacking official numbers, I was going to just use Tee Dee .049 numbers as a reference.  But looking at the data sheets available on Bernie's site, there are two data sheets for the Tee Dee .049 engine.  The data sheet from 02/61 for the Tee Dee .049 and .15 engines, and the later sheet from 02/82 for the Tee Dee .049, .051, and .09 engines.

The top end numbers for the .049 are a little different, but the low end aren't.  Maybe this is because they stopped doing the tapered cylinders in the mid to late 70's?

02/61:
5Dx3P      23,000 RPM
5.5Dx4P   18,500 RPM
6Dx3P      18,500 RPM

02/82:
5Dx3P      21,000 RPM
5.5Dx4P   17,000 RPM
6Dx3P      18,500 RPM

The purpose of my proposed build of a KB clone is not to get the highest RPM, but to get the max horsepower to turn a 6x3 prop on a control line plane.  This would be a departure for me as I'm a died in the wool 5x3 rubber ducky fan. There was talk of not doing the Junkyard Wars at Brodak this year and replacing it with a One-Design contest using the SIG Skyray and limiting it to reed valve engines.  The CD changed his mind and they will have a Junkyard Wars after all, but there might be an unofficial Skyray fly-off anyway.  This will be my first Brodak contest, and while I am no threat to any of the competitors, I thought a Skyray with a KB clone turning a Cox competition grey 6x3 would do well.

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edit:  The Sceptre flight article on the Tee Dees from 11/61 states the Tee Dee .049 will do 24,000 RPM with a plastic 5x3 and 18,000 RPM with a 6x3 prop.
The SceptreFlight article from 12/61 had 21,900 on a 5x3, 19.8 on a 5.5x3, and 18,300 on a 6x3.
The Sceptre flight article from 11/62 had 21,000 on a 5x3, 18,200 on a 5.5x4, and 18,400 on a 6x3.

Sceptre flight also has horsepower peaking at either 19,000 RPM, 21,000 RPM, or 22,000 RPM, depending on fuel and prop I guess.  So, the Sceptre Flight articles are all over, and I'll just ignore them and go with the Cox charts.

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Post  Ken Cook Sat Dec 31, 2022 5:18 am

Having attended Brodak's on several occasions, I will say that IF they decided to cancel the event, it wouldn't be a good decision. It's also good to know that the event is not going to change.  Junkyard wars was a event created by Mary Knight and her husband Al.They started the event initially flying junk and a occasional finish into a trashcan.  John owns a supermarket and he would provide the wooden fruit crates for the event. This wood was heavy, split to all heck and darn near impossible to glue. This was the true spirit of the event as it limited one to only a few options. That was the fun of the event to stir creativeness into everyone offering a limited amount of time to do so. You don't get to build these planes off site and bring them to the event.

                Junkyard wars have always been flown after dinner on the Friday of Father's day weekend. Therefore, there's also not a lot of time. So to expedite things, it was agreed to build the planes prior mid week usually Wednesday, fly the planes Friday. Not everyone is on par with Cox engines. They can and have been problematic especially a reedie. With getting it to run, and keeping the engine running in it's proper orientation. I see many issues which would cause not only a loss of interest but a severe impact of time if the Skyray decision was made.

I don't have anything to do with this kind of decision, I do know some of the big participants within the event. My personal opinion is why change a event that so many enjoy and have had fun with? It seems as if everyone tries to fix something until it's broke.
               So many are getting older and no younger replacements are following. Therefore, not only is the energy to do such a event dying away, so is the patience and talent levels to do so. With so many options that Brodak offers, my hats are off to those that could coordinate another event into the current mix. I'm not being a doubting Thomas, I just know how these talks and discussions usually go.
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