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Cox Engine of The Month
CEF Traveling Engine
Win This Engine!
Live on Patrol
Latest restorations
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Latest restorations
Ivanhoe Fri Feb 17, 2012 1:18 pm
Thought I'd post pics of my latest rebuilds.
First one I bought off EBay, listed as a Fox .049, missing various bits
When I contacted Fox Engines to get the missing parts I was informed that it is actually an .049 FAI Special high performance engine developed by Fox to compete with the Cox TD 049 in FAI freeflight competition. It's slightly slower than the TD, turns a 6 x 3 at around 19,200 as opposed to the TDs around 21,000, but is actually more powerful and can turn bigger props. It screams like a Cox too!
Second engine is a McCoy 35 Stunt
I've wanted for some time to build another big stunter, and now I have the engine to power it.
Last, a McCoy Series 21 19
Ugly, aint it? and by 'eck it's heavy too! I bought this because 1. It was cheap, and 2. cause I haven't got one! Still got to clean this up and get it running.
First one I bought off EBay, listed as a Fox .049, missing various bits
When I contacted Fox Engines to get the missing parts I was informed that it is actually an .049 FAI Special high performance engine developed by Fox to compete with the Cox TD 049 in FAI freeflight competition. It's slightly slower than the TD, turns a 6 x 3 at around 19,200 as opposed to the TDs around 21,000, but is actually more powerful and can turn bigger props. It screams like a Cox too!
Second engine is a McCoy 35 Stunt
I've wanted for some time to build another big stunter, and now I have the engine to power it.
Last, a McCoy Series 21 19
Ugly, aint it? and by 'eck it's heavy too! I bought this because 1. It was cheap, and 2. cause I haven't got one! Still got to clean this up and get it running.
Ivanhoe- Diamond Member
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Re: Latest restorations
nitroairplane Fri Feb 17, 2012 1:51 pm
WingingIt74 wrote:very cool!
Yeah man especially that fox!
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Re: Latest restorations
Surfer_kris Fri Feb 17, 2012 2:06 pm
Ivanhoe wrote:
When I contacted Fox Engines to get the missing parts I was informed that it is actually an .049 FAI Special high performance engine developed by Fox to compete with the Cox TD 049 in FAI freeflight competition. It's slightly slower than the TD, turns a 6 x 3 at around 19,200 as opposed to the TDs around 21,000, but is actually more powerful and can turn bigger props.
Are you sure that wasn't on a 5x3 prop?
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Re: Latest restorations
Ivanhoe Fri Feb 17, 2012 2:09 pm
Surfer_kris wrote:Ivanhoe wrote:
When I contacted Fox Engines to get the missing parts I was informed that it is actually an .049 FAI Special high performance engine developed by Fox to compete with the Cox TD 049 in FAI freeflight competition. It's slightly slower than the TD, turns a 6 x 3 at around 19,200 as opposed to the TDs around 21,000, but is actually more powerful and can turn bigger props.
Are you sure that wasn't on a 5x3 prop?
Could be typo, I'll check the test results
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Re: Latest restorations
Ivanhoe Fri Feb 17, 2012 2:29 pm
Surfer_kris wrote:Ivanhoe wrote:
When I contacted Fox Engines to get the missing parts I was informed that it is actually an .049 FAI Special high performance engine developed by Fox to compete with the Cox TD 049 in FAI freeflight competition. It's slightly slower than the TD, turns a 6 x 3 at around 19,200 as opposed to the TDs around 21,000, but is actually more powerful and can turn bigger props.
Are you sure that wasn't on a 5x3 prop?
Nope, test results from Model Airplane News, 1965 (Sorry for the poor copy)
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Re: Latest restorations
nitroairplane Fri Feb 17, 2012 2:44 pm
That is way more powerful than a tee dee!
I think ther must be an error in the results and or reporting.
Indra
I think ther must be an error in the results and or reporting.
Indra
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Re: Latest restorations
nitroairplane Fri Feb 17, 2012 3:05 pm
Ivanhoe wrote:I can only show the test report.....
Can you test your engine and tell us if it ran close to that on a 6x3?
Indra
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Re: Latest restorations
Surfer_kris Fri Feb 17, 2012 3:17 pm
The only number I can see in that test is 17400-18300rpm on a 6x3, and that's quite impressive for a .049 engine.
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Re: Latest restorations
Ivanhoe Fri Feb 17, 2012 4:13 pm
Surfer_kris wrote:The only number I can see in that test is 17400-18300rpm on a 6x3, and that's quite impressive for a .049 engine.
And as it says, giving 19,000 or just over in flight.
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Re: Latest restorations
Surfer_kris Fri Feb 17, 2012 5:07 pm
Maybe it is my poor language skills then, but to me they only advise to aim for 19000rpm in the air, and they base that on the performance curve they have obtained with a flywheel.
To hit 19000rpm on the ground with a 6x3 prop would require a hoped up Norvel .061, and there is no way a TD would make 21000rpm either. I just cannot see where those numbers are coming from.
The easiest way to sort this out is to simply make a Youtube movie on a 6x3 prop, and then we'll all know what it can do.
To hit 19000rpm on the ground with a 6x3 prop would require a hoped up Norvel .061, and there is no way a TD would make 21000rpm either. I just cannot see where those numbers are coming from.
The easiest way to sort this out is to simply make a Youtube movie on a 6x3 prop, and then we'll all know what it can do.
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Re: Latest restorations
nitroairplane Fri Feb 17, 2012 5:12 pm
Nah you language is good Kris better than mine most of the time!
I mean Wilf if you get it running that well please please take a video even with your phone!
I mean Wilf if you get it running that well please please take a video even with your phone!
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Re: Latest restorations
Ivanhoe Fri Feb 17, 2012 6:23 pm
nitroairplane wrote:Nah you language is good Kris better than mine most of the time!
I mean Wilf if you get it running that well please please take a video even with your phone!
I am not, nor have yet, as far as I can see, claimed that the engine which I have will do 19,000 rpm, I am simply showing you the 1965 test report figures, to accept or not as you see fit. The example which I have is pretty badly worn, and is a pig to start, but screams well when it does get going, so in my humble opinion, is doing a fair number of RPM. I shall probably get a new piston/liner from Fox at a later date.
I can't take a video proving anything, even if I wanted to, since I don't own a tach.
I would just point out that, if you read the test report, (and I can put up the rest of it if you wish), they measure bhp output up to 21,000 rpm, difficult to do if the engine won't achieve that. Also 18,000 - odd static rpm easily equates to 19,000 in the air, which is what they say.
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Re: Latest restorations
Surfer_kris Fri Feb 17, 2012 10:23 pm
It certainly would be difficult to reach 21000rpm, and the power curve peaks at about 19000rpm. That's why they recommend to aim for a load that has the engine revving around 19000rpm, so that it operates where it develops maximum power.
The actual curve is taken by letting the engine accelerate a calibrated flywheel, there are no props involved as far as I know. From the acceleration all the figures for the plot can then be calculated without having the engine revving statically at those high rpms.
The actual curve is taken by letting the engine accelerate a calibrated flywheel, there are no props involved as far as I know. From the acceleration all the figures for the plot can then be calculated without having the engine revving statically at those high rpms.
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Re: Latest restorations
Ivanhoe Sat Feb 18, 2012 2:57 am
As my final contribution to this particular thread, I can only quote Doug Martin, who supplies all the obsolete Fox engine parts now, answering a question on a FF Power Forum -
"As the supplier of the Fox .049 FAI Special I have tried to give folks the thought that running them up past 19,000 is lost effort because it is such a long stroke engine. The torque curve drops off so fast after that,"
Fini
"As the supplier of the Fox .049 FAI Special I have tried to give folks the thought that running them up past 19,000 is lost effort because it is such a long stroke engine. The torque curve drops off so fast after that,"
Fini
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Re: Latest restorations
Surfer_kris Sat Feb 18, 2012 5:37 am
I was merely objecting to the inflated rpm ratings of both the Fox engine and the TD. A 6x3 prop is in most cases a bit too much for any .049 engine.
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