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Building Tips and technical articles. => 1/2 A building. => Topic started by: Larry Renger on May 07, 2012, 04:28:32 PM
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I have the standard Fox .049. I broke it in for about 1/2 hour and it would hold a steady 2 stroke at the end. I am using 15% Nitro fuel and a 6x3 prop. It sounds great on the ground and initially in the air. However, on my Lil Geo it has arbitrarily quit all three flights. Twice inverted, causing damage both times.
Does anyone have experience with this engine that would indicate that I should do something different?
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I sounds like you're already in the top 5% of Fox 049 owners.
The next step up is into a TeeDee.
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Tee Dees I got, and know how to run. I want this airplane to fly with the Fox! I worked for Duke for a while, and it is a nostalgia thing. I don't want to run .35s (I have an outstanding one, Ceramic liner L&J), and the .15 seems hopeless for consistency. The .07 and .09 are strange. So the .049 is it!
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Hi Larry,
I remember reading about Doug Galbreath's backplate engine mount and how it is supposed to fix some run problems with the Fox 049. Maybe he is worth contacting?
-Chris
http://freeflight.org/phpBB3/viewtopic.php?f=6&t=352
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Excellent input! Thanks. I have a lathe..... >:D
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Well, I am up to 6 out of 6 flame-outs. The latest with 25% Nitro fuel. I will have to try the backplate thing next, I guess.
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This isn't a plug related problem is it Larry? I had a .07 that was giving me similar fits. I would take the plug out and it would glow fine. I replaced it and problem solved. The real problem is the rarity of the plug. Ken
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This isn't a plug related problem is it Larry? I had a .07 that was giving me similar fits. I would take the plug out and it would glow fine. I replaced it and problem solved. The real problem is the rarity of the plug. Ken
Ken,
Your more correct then you realise. Updating to a Nelson or a turbo is a definte improvement.
Dennis
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Hello Larry,
Treat yourself to a Mattes Rework adapter ring, then you are good to go with a whole range of plug/head combos or even a Cox head. I suspect you won't regret it.
Regards,
Andrew.
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Larry,
If I remember correctly, there were two iterations of the standard Fox .049. The second one ran much better than the first. You might want to check what Duke changed if you have the earlier version.
My two are the FAI versions so I really have no experience with the standard one.
George
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Hello Larry,
Why not talk to Doug Martin about your problem. He is the guy that assembles them these days. If anyone would know what the problem was, he would.
My Fox 0.49 was ,I believe, built up by Doug and despite the sneering comments of some others, it goes very well indeed and I am right pleased with it. Doug's email address is dougsengines@hotmail.com, he seemed a helpful sort of guy when I dealt with him.
Regards,
Andrew.
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Back in the day I knew nobody who would use a Fox .049. I have two FAI Fox .049's and they seem decent. I had standard Fox .049 but never used it. It looked real good and think Andrew bought it. I was told about the backplate issue and flame outs. Did you get a Galbreath backplate???...himmmm I know FF guys like the FAI so the standard should work also. Maybe try low nitro fuel say 10%. Could be a design thing, who knows ??
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I've seen many of these engines the standard .049 run and they always seemed pretty strong. I know many used them for Musciano events as well. What I did see was the crankshafts breaking. Ken
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I have ordered the Mattes ring and will make my own stuffer backplate. Then we will see. I may also change out the fuel tank for one I KNOW works.
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Larry, do you have any updates? I am experiencing the same issues with mine. I contacted Doug Martin and he mentioned someone in CA with a lot of Cox experience was having issues. He didn't name names but I'm thinking you may know who I'm talking about #^. I'm running a Merlin plug with a homemade clamp ring, 15% Sig Champion, on a BHM Flight Master. I am seeing 18.5 K on a 5/3 APC. Runs fine straight and level but dies when attempting manuevers. Doug said perhaps the nva is pointed wrong or that the Venturi is too large and needs an insert. Sound familiar? ???
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Boy does it ever! I finally had time to do some running on mine and it is still not handling maneuvers. I have the Cox thread adapter and a Galbreath/Nelson head combo. I made a stuffer backplate, and a venturi insert to cut the flow area. I have a Cox fine thread needle, and the hole is larger than the Fox one, and definitely in the optimum position.
I think the crankshaft fit may be a bit tight. Also, I plan to grind on the crank to improve balance. More as it develops! HB~>
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Hi Guys,
I have a Fox 049 of the "Comet-Repo" vintage. There are some grinder marks where the Comet logo would have been.
I am using the stock head and noticed it has just a single bypass port.
I did some bench runs on it today using Powermaster GMA blend (10% nitro, 11% castor, 11% synthetic).
Ran through a couple of tanks ok after I got the hang of starting it. Basically I had to open the needle to get her to start, then turn it in to get decent RPM's.
I am planning to pass it on to a friend for a project so I am interested to see how it works for you.
-Chris
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Chris,
The one I have is a single bypass but no comet marks. I got it a couple years ago from Henry Werner when he had a shop in Northern VA. He got them from Doug. I also have an FAI version and have only bench run it. It runs fine as long as I just fly level but quits when I try ANY manuevers! It seems to have decent power when it runs, but I have switched to a Black Widow for next weekends Muciano event.
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I made a stuffer backplate, and a venturi insert to cut the flow area. I have a Cox fine thread needle, and the hole is larger than the Fox one, and definitely in the optimum position. HB~>
How big is your venturi insert and what is the optimum position for the nva hole?
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I found the closest K&S tube that nearly fit and filed it down until it would go in all the way. Then I filed a pair of notches so it would go past the spraybar a bit more than half way. Used JB weld to bond it in and then chamfered the top for smooth entry flow.
Of course, I was doing it the hard way. The simple way is to totally disassemble the engine, drill the venturi to fit the tube, glue it in and finish the top (the sharp edge on the bottom is a GOOD thing, it turns out), cross drill for the spraybar, and re-assemble.
The hole in the needle should be about 15 deg. below just across the venturi. I usually put it forward, but I doubt it matters. Not straight across or straight down. Anything inbetween will work better than those two positions.
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When trouble shooting my Fox .049 sport (pre-64) we found the spraybar had a really small orifice. It measured about .017" dia.
A Cox .049 reed engine spraybar measured .040" in comparison, and a Cub .049 spraybar orifice measured .025".
We had damaged the original spraybar removing it, so we drilled out the replacement spraybar orifice to .025" (same as the Cub). The Fox had refused to richen up when we first ran it, even with the needle all the way out. My friend has the same engine, and it ran almost identical to mine.
After installing the new spraybar, and sealing both sides with J-B Weld (to be sure there were no air leaks), it ran perfectly! We have not modified my friends engine like this, but suspect it will cure his run problems as well.
I realize that this could also have been caused by air leaks, but the small orifice on a relatively hot engine (for the period when it was made) just didn't make sense.
Bill
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I give up on this engine. It seems that my "balance improvement" efforts have caused the engine to produce massive vibration. OOPS! Even locked down hard to a massive cement bench, it runs erratically. It is going to get mounted on the "Zombie Terror" which has had the leadouts clipped. Never to be flown again.
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Larry, Did I read that you were making tanks using film canisters as tanks, and using something to adhere the tubing to the plastic?
If you would refresh my memory I sure would appreciate it...
Thanks, Gil
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Film cannisters and most small plastic bottles work fine. The glue I use is "Goop" adhesive.
Bottles from the "travel size" section in your pharmacy or supermarket are a great source, as are some of the bottles from liquor "miniatures". My favorite, the APS film cannisters are no longer made. >:(
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Film cannisters and most small plastic bottles work fine. The glue I use is "Goop" adhesive.
Bottles from the "travel size" section in your pharmacy or supermarket are a great source, as are some of the bottles from liquor "miniatures". My favorite, the APS film cannisters are no longer made. >:(
Hmm...as time passes and technology advances we have gone to digital photos so there went the film canisters. Fortunately...or not...many of us now have small medicine bottles to replace them. :-(
George
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I hear you George. I was looking at my medicine a few days ago and wondered why I ever thought I needed film canisters. While I've never flown a medicine bottle, I do have one on a test stand.
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Film cannisters and most small plastic bottles work fine. The glue I use is "Goop" adhesive.
Bottles from the "travel size" section in your pharmacy or supermarket are a great source, as are some of the bottles from liquor "miniatures". My favorite, the APS film cannisters are no longer made. >:(
Larry, I have a couple of grocery sacks full of canisters, probably several hundred...lifetime supply and all that you know. I hit all the photo-development places a couple of years ago when I realized they were going to become obsolete. I'll send you some if you need them, I'll never use them all. just let me know.
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Thanks, Ray! If you could spare a half dozen of the APS, it would be wonderful! I tried the same thing a couple of years ago, but only got 35mm cans.
BTW, having given up on the Fox, I cut the nose of the Geo way back and am installing a firewall with setup for the Atwood style mount. So far as i can tell, it works for the Holland Wasp, Atwoods of all stripes, the Cub .049X and the McCoy diesel.
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1. are you using 2 tubes to the canister ?
2. how about a photo..
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Do a search in this forum on "tanks" and you will see a wide variety of applications. Just about every possible configuration has been done and shown here.
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Seems lately I have acquired a lot of medicine bottles or is it pill bottles. I call it drug bottles that the doctor is pushing. May have to try one.
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Do a search in this forum on "tanks" and you will see a wide variety of applications. Just about every possible configuration has been done and shown here.
Hi Larry,
Just for fun I did a search in this section (1/2A) and found exactly 4 posts on "tanks", including yours that I quoted.
That really surprised me!
BIG Bear
RNMM/AMM