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Cox .074

Old 02-01-2009, 09:44 AM
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Honker1
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Default Cox .074


Hello all,

I have a Cox .074 someone gave me. Have only run it briefly and was wondering how they perform, do they perform and are there any standard hop up tricks.

Any one?

Honker1
Old 02-01-2009, 10:00 AM
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combatpigg
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Default RE: Cox .074

No one that I know of has done the AME hop up mods to one of these. The standard is 17,000 with a 7x3 prop. APC has a good selection of props in the 6x4 size range if you are looking for more speed. These engines are so bulky that setting one up for a serious speed project does not make sense.
I think the main reason why there isn't much message traffic about hopped up .074s is because they run so well as is. Norvel never bothered to come out with an AME version of it.
Old 02-01-2009, 10:39 AM
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digital_trucker
 
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Default RE: Cox .074

cp - I'm pretty sure Norvel NEVER came out with an AME version of ANY Cox engine

Honker, the The Cox .074 Queen Bee is somewhat low in power output. Not really much more powerful than than a good Cox .049. One the plus side, they're reliable, throttle well, and have the famous Cox durability.. There's not much you can do do hop up one of them, if I were you I'd just enjoy it. If you want a hot performer, then I'd go with something different.
Old 02-01-2009, 02:38 PM
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combatpigg
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Default RE: Cox .074

OOOps!
I never could get my QBee to run. I bought it after reading a glorious product review by Chris Chianelli. I sent it back to Cox and they said it was just fine.
I never could get it to run. It's the only engine I ever bought that falls into this category. By then Norvel was getting a toe hold in the market with engines that put out great power but were hit & miss for reliability.

Knowing what we do know about all the little tricks to help a Cox engine run better could apply to the QBee, but IIRC mine didn't have enough compression to put out a burp. Fixing that problem is like trying to teach a short basketball player how to be tall.
Old 02-01-2009, 02:51 PM
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Default RE: Cox .074


ORIGINAL: combatpigg

OOOps!
I never could get my QBee to run. I bought it after reading a glorious product review by Chris Chianelli. I sent it back to Cox and they said it was just fine.
I never could get it to run. It's the only engine I ever bought that falls into this category. By then Norvel was getting a toe hold in the market with engines that put out great power but were hit & miss for reliability.

Knowing what we do know about all the little tricks to help a Cox engine run better could apply to the QBee, but IIRC mine didn't have enough compression to put out a burp. Fixing that problem is like trying to teach a short basketball player how to be tall.
Hic....[sm=confused_smile.gif] So, you expect to live this one down so quickly? Too many witnesses.

Queen Bee .074's run best on Alpo and fresh water. They don't seem to like glow fuel.

MJD
Old 02-01-2009, 02:57 PM
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combatpigg
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Default RE: Cox .074

I didn't have too much to drink, but I ate the worm.
Old 02-01-2009, 09:53 PM
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DeviousDave
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Default RE: Cox .074

My .074 ran well, but suffered from a lack of Testicular Fortitude. It (barely) flew my Aerocraft Snapper, then gathered dust. I gave the other new one I had away. Just a real dissapointment.
Old 02-02-2009, 03:48 PM
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Dukester
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Default RE: Cox .074

Haven't posted in a while, but my favorite quote somebody told me after I bought a Queen Bee at a swap meet - "Raging power of a .049 and the weight of a .10".

Still makes me laugh.

Duke
Old 02-02-2009, 03:56 PM
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Default RE: Cox .074

Sounds like an AP .09,,,,the power of an .09 with only the size and weight of a ,,,,,,.15
[sm=lol.gif]
Old 02-02-2009, 04:17 PM
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flyinrog
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Default RE: Cox .074

The queen bee was only supposed to have the power of an .049 with throttle and muffler attached...per the cox paperwork that I have...Rog
Old 02-03-2009, 01:51 AM
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Default RE: Cox .074

My son had a QB in a Davey Systems Fly Baby some years ago. Looked like a perfect match, I assured him it would be a great flyer. Wrong! The QB barely lugged it around on the edge of a stall. It (the QB) had lots of slop in the ball socket. I tightened it up for him and it improved the starting, (which wasn’t all that bad to start with) but nothing that you’d notice in the flying. I would love to have that little plane now. He did a nice building job. With a Norvel .049/.061 it WOULD be a great flyer.
Al
Old 02-03-2009, 02:10 AM
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Default RE: Cox .074

The QB I bought had a straight cylinder. There was zero compression with it, very disappointed.

It is now polished and sitting with the collection, or used for an occasional paperweight.

It looks like a Cox, but never did run like one.

I want to maybe convert it to an .09 cylinder and use it in a boat. The rear intake fits right in to what normal boat engines are like.

With a turned-around muffler it would work good to route an exhaust tube out the side to keep the engine bay somewhat clean, and it having somewhat of a normal RC carb is nice. Just wish it had more power. They are heavy for their size.

The QB has the LOOKS to be a real powerhouse the way it is designed, but it just don't have the poop. It's too bad.
Old 02-03-2009, 09:17 AM
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Default RE: Cox .074

I have QB on a small bipe that I picked up used many years back. The engine seemed to run alright, though it started backwards about 3 out 4 times. But I never could get the thing to fly worth a hoot. Theory #1 was that it needs a bigger engine. I remember when I was looking for a prop, someone told me to consider it a "Well Muffled .049 with a throttle"
I hope to try it some more this summer, but I expect to be in the market for a .15 before long.
Old 03-14-2014, 07:54 AM
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Originally Posted by combatpigg View Post
OOOps! I never could get my QBee to run. I bought it after reading a glorious product review by Chris Chianelli. I sent it back to Cox and they said it was just fine. I never could get it to run. It's the only engine I ever bought that falls into this category. By then Norvel was getting a toe hold in the market with engines that put out great power but were hit & miss for reliability. Knowing what we do know about all the little tricks to help a Cox engine run better could apply to the QBee, but IIRC mine didn't have enough compression to put out a burp. Fixing that problem is like trying to teach a short basketball player how to be tall.
I find it interesting, CP that you've also had problems with the QB-074. Mine has compression, but previously I have never gotten it to run successfully. Someone mentioned not long ago that I need to change out the Cox glow plug for another is the trick. I just assumed that the Cox engines ran so well, I never suspected the plug. Overall, from what others say, as a sport engine, it runs quietly and constantly, about the power of a Tee Dee 049. From what I gather, the Thunder Tiger GP-07 has about the same power. Seems once you start muffling these small engines, that it robs sufficient power from them.

I had good luck with a Norvel Big Mig 061 CL engine in an RC plane with MECOA 049 long plug Texaco glow head/plug adapter, but that was unmuffled. I think these little buggers were made to scream unmuffled, but then you need to fly them where no one can hear your screams.
Old 03-14-2014, 12:44 PM
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This is an old thread. Just checking through my notes here. I used a 6 - 3.5" prop, 10% fuel and no muffler on all three motors. The Cox .074 went 15,400 rpm. I think it was on the 1/4-32 conversion head, not the TD .09 head. It really shouldn't use the muffler if you want it to fly respectably. My TT .07 went 14,900 (it says 6.3 - 4" prop?) I fiddled with it a bit with port matching and a Turbo head and got it up to 18,000. The Norvel Big Mig was 18,900 on the 6 - 3.5. Oh I found a Norvel .06 tested with a 6-3 MA at 16,500. When comparing the Queen Bee to a TD .049 it has to be remembered that it is a reedy, and if you want to be somewhat 'fair', a TD .049 is seldom run with a muffler - or throttle for that matter. I think the QB muffler is just NFG on it, as Galloping G was saying.
Old 03-14-2014, 01:49 PM
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Yes, it is an older thread, but topic was relevant. I found it in a search. I found CP's comments spot on.

You're tweaking the GP-07 brought it near in-line with Norvel levels. Not sure why the manufacturer toned it down when it was capable of producing more with just a little more effort.
Old 03-14-2014, 05:55 PM
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The crank to case clearance in the TT .07 is inexcusably sloppy, and the bypass ports don't match well on the older ones. I haven't found much difference by matching them, but the plug is what slows it down. It idles nicely, but it is hard to open up the carb or use it for control line. I have a TT .10 that is a slug too, and it didn't respond to a new head either. I spent a fair bit of time with that one to no gains. The Norvels have a good plug, as well as most of the Cox stuff. They know that is the trick on the little motors.
Old 03-14-2014, 06:57 PM
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Regarding the TT GP-07, I'm putting it in a 1959 Berkeley Impulse RC build. Plane has 46" wingspan with about 295 sq. in. wing area. Nose cheeks came in too narrow for the Enya 09-III TV, which is my preferred engine. With a 7x6 wood prop, it definitely would not be considered underpowered. I'll know more when I actually try to fly it.
Old 03-15-2014, 08:15 AM
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The .07 seems to like a smaller prop, unlike the steel piston, loop scavenged Enyas. 6-4? on that plane which I will have to search for a pic. (OK, found a pic in the Cox engines forum)

Last edited by aspeed; 03-15-2014 at 08:54 AM.
Old 03-15-2014, 10:36 AM
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That I could understand, aspeed. It's maximum horsepower is around 18,000 rpm, so by selecting a prop that puts it in its range makes it happy. From the forums I've heard that the 6x3 prop is best for it. For me it will require experimenting, as the airframe would dictate the best prop to use.

You're right on the Enyas. I found that the Enya 09-III TV likes lighter wood props best. It hauled a heavier 049 ARF 049 like with a 7x3 prop, but really moved out with a 7x6. According to Peter Chinn's data, 12,000 RPM is where HP maxed out. He mentioned that there is no use is using smaller props than 7x4 on it. I wanted to give an 8x3 prop a shot, but those are no longer made in wood.
Old 03-16-2014, 09:00 AM
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The regular glow plug is a power robber and that's the major problem with the QueenBee...

With a Turbo plug it will do about 17500rpm on a 6x3 prop. There is a thread on that here; http://www.rcuniverse.com/forum/1-2-...first-aid.html

Other fixes include adding a fixed airbleed etc.
Old 03-16-2014, 10:23 AM
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A Turbo plug wouldn't work with a 1/4 - 32 hole in already? That is how mine was. I used the .09 TD plug, and it seemed ok. I forget which one I used for my test, and the difference in rpm. It is too cold to check things now. A burned out TD head could likely be used for the Turbo plug. Is that what you used? I won't do it until my TD head burns out, and it isn't mounted on a plane right now. I think some muffler drilling and grinding would help things along too. Mine went ok with no muffler. The carb dia is kind of small, but looks like it is at the max already without making a new assembly.

Last edited by aspeed; 03-16-2014 at 10:38 AM.
Old 03-16-2014, 10:30 AM
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The instructions say 17,800 is "typical" for a 6-3 prop. I tend to think it is typical of the best hand-fitted example they ever ran on their test bench. If one single example was known to have achieved this then I am Cox would have no compunction about putting this in print (or any other mfg, not singling out Cox).
Old 03-16-2014, 10:53 AM
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There were some things going on with Cox prior to their purchase by Estes Industries. Seems these engine companies prior to failing did some things that weren't the best for the market. For K&B it was the release of their Sportster series. For Testors, it was their Series 21 engines. Cox 074 Queen Bee also was a poor fit. Overall were they bad engines? No. For K&B, the new technology wasn't tolerant of abuse. Engine was easily ruined by simply running lean, and they were heavy. Testors Series 21 were too heavy and cross scavenge technology as good as it is was losing out to Schneurle. Cox Queen Bee is heavy. Modelers were looking for a Tee Dee like offering. Weaker power through reed valve technology plus the heavier weight disappointed the modelling community.

Seems almost like these companies were grasping for straws, and finally faded away.
Old 03-16-2014, 11:09 AM
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The Cox Conquest .15 was a good reach out. Still a great performer by today's standards. IMHO the best Cox ever. The .074 was because of the RC market wanting a throttle and muffler. Too bad the little guys don't like mufflers.

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