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Author Topic: Cox 1/2A Product engine.  (Read 1743 times)

Offline John Rist

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Offline Fredvon4

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Re: Cox 1/2A Product engine.
« Reply #1 on: November 12, 2018, 12:44:43 PM »
John is this tongue in cheek?

few years back the cast product engines were selling in LOTs for between $3 to $6 per engine

But I guess today for $20 a saw buck cheaper that CoxInternational or ExModelEngines ...they ask $29.95 and no props

Ha Just noticed California Dan...I have bought a boatload of stuff from him
"A good scare teaches more than good advice"

Fred von Gortler IV

Online Mark Mc

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Re: Cox 1/2A Product engine.
« Reply #2 on: November 12, 2018, 10:57:30 PM »
The thing that makes these a reasonable buy is the props.  For what you'd pay for 10 props from Cox International before shipping, you get an engine thrown in for free....

Mark

Online Larry Renger

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Re: Cox 1/2A Product engine.
« Reply #3 on: November 14, 2018, 07:42:09 AM »
Recent batches of props have had problems! If you get the deal, try flexing the prop blades. The bad ones will show rows of surface cracks across the blade. Back when they were done right, the plastic had to be 6-6 Virgin Nylon. No regrind allowed!
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

A closed mouth gathers no feet!

Online kenneth cook

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Re: Cox 1/2A Product engine.
« Reply #4 on: November 19, 2018, 04:27:33 PM »
            I could be incorrect on this but I believe the square tip 3 bladers are pushers whereas the rounded tips are tractor props. So what do you do with all those pushers?

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #5 on: November 19, 2018, 04:38:29 PM »
Reedies will run either way....

Online kenneth cook

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Re: Cox 1/2A Product engine.
« Reply #6 on: November 19, 2018, 04:45:46 PM »
         Except for the way you want them to run

Offline john e. holliday

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Re: Cox 1/2A Product engine.
« Reply #7 on: November 20, 2018, 11:55:40 AM »
I now have two of those engines with the left hand props that I hope to get some runs on. With the left hand props maybe it won't be so hard to keep the lines tight for the grand kids.  Oh, the props look great even after I tried to break them. D>K
John E. "DOC" Holliday
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Online Larry Renger

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Re: Cox 1/2A Product engine.
« Reply #8 on: November 20, 2018, 07:17:07 PM »
Yup, some good, some bad, but well worth checking each one!

Be afraid, be very afraid! I actually had a 6-3 shed a blade on starting. That was my first clue that something had gone sour.  ~^

Old props seem to be OK. I think the recently molded ones haven’t the right plastic or poor molding temperatures. I know that there are a lot of factors in getting plastic molding right, but don’t have the knowledge to recommend corrections.

But it is easy to see if your props are OK. Flex the blades and look for surface cracks. The old props could almost be bent double with no problems. They would retain a bit of bend, but no surface damage.

Boiling does not seem to help the defective props.  >:(
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

A closed mouth gathers no feet!

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #9 on: December 11, 2018, 06:48:05 PM »
Gents:

Steering this thread in a different direction. I've got a couple of these on hand and am contemplating a 1/2A SIG Skyray. Clearly the firewall mount presents a problem. Any advice on how to get this done with some kind of adapter, or even if it can be done? I've got a Babe Bee for fallback.

Much obliged.

Dave Mo...

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #10 on: December 11, 2018, 07:21:02 PM »
Sure. You have a couple of simple options with the recent model product engines*:

1. Build up a 3/8" thick "U-shaped" plywood firewall spacer to sit on the normal 1/8" plywood firewall. This will allow clearance for the intake tube. No changes to the engine required. Some guys like this configuration because you can easily choke the engine. I haven't really found this necessary on a Cox. They like a port prime. Or,

2.  Remove the intake tube and discard it. Screw the plastic engine backplate right to your plywood firewall. Put a breather hole thru the firewall where the venturi is located, and crossdrill the balsa nose block for an air passage. The fuel line will run out the bottom, just as in option 1. You may need/want to cut down the needle valve so that it does not vibrate and fail in fatigue. Or, you can substitute a different Cox needle, such as the shorter one from the Killer Bee.  Note that the product engine backplate is very close in design to the Killer Bee backplate. A few differences in the ribbing, the KB doesn't have the intake screen, and there may be a difference in venturi size, and it is red.

Note that your hole pattern will not be the same as for the classic tankmount installation. The plastic backplate has a bit smaller pattern, with a trapezoidal orientation. I find that the hex-recess screws are a lot friendlier for installation than other screws.

Good luck with your project!

Divot McSlow


*--For old model product engines which carried the product number 290, you need a Dale Kirn sheetmetal mount, as shown in one of the old model magazines. There was also a similar molded plastic part that was made/distributed by one of the usual parts suppliers. I don't recall if it was Goldberg or who. These may be hard to find. But you can definitely make up the bent sheet metal version. When you get done, it will be a similar installation to the modern backplate installation.

https://www.coxengineforum.com/t7914-dale-kirn-s-290-special
« Last Edit: December 11, 2018, 08:19:05 PM by Dave Hull »

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #11 on: December 12, 2018, 11:15:22 AM »
Hey, Dave:

Thanks for the well-considered response. Lots of good info there.

I do have one of the 290 motors, and can make a pair of mounting brackets per the great link you provided. I've got mixed feelings about cutting off some of the plastic backplate, but these mills might be a dime a dozen. So no harm in that I guess.

As you can see below, I do have one other Cox motor. It has the trapezoidal mounting pattern you referred to, but without the breathing tube. Mounting it and allowing space for the screen air intake will be a breeze. However, is there anything you can tell me about this motor as far as age and type are concerned? Can't find a number on the cylinder, but it does have two intake ports.

Thanks again, Dave...

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #12 on: December 12, 2018, 11:18:07 AM »
Dave:

Oops! The image above doesn't show that that mill has slit exhaust ports and a curved heat shield behind the cylinder.

Dave Mo...

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #13 on: December 12, 2018, 12:50:53 PM »
Looks like a typical late model Sure Start product motor built in the mid-1990's.  That exact engine was in some of the last PT-19 Trainers that were built. Also in the Extra 300, except that one did not have the exhaust shield installed. And probably in a lot of others. In any event, it is a good general purpose 1/2A engine with decent power from dual ports. The weak spot in these would appear to be in the journal bearing, where the crank may spall the aluminum bore. Good fuel is a must. Polishing the crank can help if the surface finish is not as good as it could have been. The later model engines were not manufactured to the higher standards of the earlier engines, which in my opinion were simply jewels. Talk about precision....

One thing to be aware of is that these engines may have gone thru several owners and been reconfigured in non-standard ways. I do it all the time to use the best parts or get a configuration I want. Even the factory made all kinds of weird configurations at times to use up parts?  (For example, the brass drive washer was for pusher applications, but seemed to start showing up at random on other applications.) My next engine is  for a P-40 Guillows model, and will have a product engine case, crank, drive washer and ratchet starter; a Killer Bee plastic backplate but the needle from a sure start since I need the extension; a ground-OD cylinder with side port muffler to get the exhaust out of the cowl, and a standard glowhead. Hope I can get back to work on it sometime soon....

Divot McSlow

Offline George Hostler

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Re: Cox 1/2A Product engine.
« Reply #14 on: December 12, 2018, 03:31:37 PM »
I've got a couple of these on hand and am contemplating a 1/2A SIG Skyray. Clearly the firewall mount presents a problem. Any advice on how to get this done with some kind of adapter, or even if it can be done?

Dave, the choke tube was added for convenience. You are not required to use the choke tube, it can be removed. Another easy solution is nylon standoffs. I got these from a home improvement center hardware drawer.

Offline George Hostler

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Re: Cox 1/2A Product engine.
« Reply #15 on: December 12, 2018, 04:18:39 PM »
Looks like a typical late model Sure Start product motor built in the mid-1990's.  That exact engine was in some of the last PT-19 Trainers that were built. Also in the Extra 300, except that one did not have the exhaust shield installed. And probably in a lot of others. In any event, it is a good general purpose 1/2A engine with decent power from dual ports. The weak spot in these would appear to be in the journal bearing, where the crank may spall the aluminum bore. Good fuel is a must. Polishing the crank can help if the surface finish is not as good as it could have been. The later model engines were not manufactured to the higher standards of the earlier engines, which in my opinion were simply jewels. Talk about precision....

One thing to be aware of is that these engines may have gone thru several owners and been reconfigured in non-standard ways. I do it all the time to use the best parts or get a configuration I want. Even the factory made all kinds of weird configurations at times to use up parts?  (For example, the brass drive washer was for pusher applications, but seemed to start showing up at random on other applications.) My next engine is  for a P-40 Guillows model, and will have a product engine case, crank, drive washer and ratchet starter; a Killer Bee plastic backplate but the needle from a sure start since I need the extension; a ground-OD cylinder with side port muffler to get the exhaust out of the cowl, and a standard glowhead. Hope I can get back to work on it sometime soon....

I don't think it was a matter of degraded precision. You probably already know this, a historical summary is contained in https://en.wikipedia.org/wiki/Cox_model_engine

I am told that when the Estes Corporation, the model rocket company purchased Cox Engines in 1996, from that point they were basically assembling engine from left over parts. Cox had a few key ladies who knew how to quickly match cylinders to pistons with the best fit, Estes did not. Thus, there were engines that had poor compression as a result. Plus, they mixed and matched parts where that if one got a so called "Venom", one of the hottest Cox reedies could have received something less than that. As they ran low on parts they substituted. So, you may find a conglomeration there if from those Estes production runs.

Later engines are being cobbled together by Cox International Canada and Ex Model Engines along with a few others. However, they seem to be doing a better job in their assembling, plus doing limited production runs through subcontractors where parts are short and there is still a market for them.

Their costs may seem high, but we no longer have the mass produced quantities that Cox of California was pumping out in its hay day, which kept costs down. I've used an inflation calculator to compare costs. Their costs are a touch higher but not by much. (We also had more disposable income 40 years ago as taxes were lower then.) They are also disadvantaged by local labor costs, which are by nature higher than costs of labor overseas. It's all a part of local cottage industry environment that CL is now surviving on (IYKWIM). D>K

Estes was on the way out in 2008, April that year I bought 2 Sure Start engines from their surplus store for $6.99 + $7.99 shipping. Then their engine shop closed completely in 2009. Various buyers to include Cox International and Ex Model Engines along with a few others purchased their remain inventory to include engine parts after that.

But you are right, when buying things used, no telling what a previous owner may have done with an engine. Because parts are interchangeable, I even remember back in the 1970's buying parts from Sears, Montgomery Ward, etc. If they were out of stock with one cylinder piston set, I'd just buy what they had on the shelf. Then, Cox racing fuel was readily available in the stores. if the engine wasn't running with enough power, I use that. So mixing and matching becomes possible. Taking a donor engine, removing the plastic backplate and replace the worn tank engine got someone back to flying again.

So, it is possible to get a surprise or two when buying stuff used.

Offline john e. holliday

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Re: Cox 1/2A Product engine.
« Reply #16 on: December 12, 2018, 05:23:45 PM »
Mine started and needled very easily.  Have two runs on both of them. H^^
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
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Have fun as I have and I am still breaking a record.

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #17 on: December 12, 2018, 05:59:08 PM »
Doc,
I've heard of flying a shop rag with an .010, but you got me with your latest innovation---a twin stick. How does it fly?

Divot McSlow

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #18 on: December 12, 2018, 07:29:25 PM »
Some nifty responses!

Dave: Ah, so mid-nineties it is! It looks almost new/old stock as the cylinder still has circular honing marks, and nothing apparent in the vertical. Screw heads pristine, standard Cox glow-head.  Maybe one run on it, maybe not.

I intend to polish the crank with 1000 up to 3000 grit paper. To release the crank, will tap on a machine screw (not the stud) and a touch of heat on the prop driver. When I fire it up, my plan is to use 25% nitro and 20% all castor.

George: Those spacers look like just the ticket. Will see if I can latch onto some at Menard's or Home Depot.

John: Those are some beautiful mills. However they do give me choke tube envy! Ha!

Gracias to all the hombres here.

Dave Mo...

Offline john e. holliday

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Re: Cox 1/2A Product engine.
« Reply #19 on: December 12, 2018, 09:20:32 PM »
Doc,
I've heard of flying a shop rag with an .010, but you got me with your latest innovation---a twin stick. How does it fly?

Divot McSlow

That is my temporary test stand/wood.  I move the tank over when I run the other engine.   D>K
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
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Have fun as I have and I am still breaking a record.

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #20 on: December 12, 2018, 09:23:48 PM »
Dang, Doc--I thought you were going to tell us that you had one running CW and the other CCW and it was a "helicopter stick." And with a full tank in each, it would blow thru the 400' ceiling like a Musk-rocket.

Divot

Offline George Hostler

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Re: Cox 1/2A Product engine.
« Reply #21 on: December 12, 2018, 11:03:21 PM »
Regarding flying rags and other weird helicopter like contraptions, there are a couple designs of weird free flight single bladed oddities that flew similar to a single bladed maple tree seed. One originated from UK called the Charybdis by Charles MacCutcheon:

https://outerzone.co.uk/plan_details.asp?ID=5275 60-in. span from July 1954 Aeromodeller

With variant by DM Sherrerd for 1/4-A Tee Dee:
https://outerzone.co.uk/plan_details.asp?ID=3541 41-in. span from October 1972 American Aircraft Modeler

and variant by Ken Willard for Cox .049 reedy:
https://outerzone.co.uk/plan_details.asp?ID=5264 54-in. span from March 1984 Model Builder

The  Charybdis in action (5 minute video):

Offline john e. holliday

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Re: Cox 1/2A Product engine.
« Reply #22 on: December 13, 2018, 11:18:52 AM »
Seen one like that on one of the British FF fun fly meets.  Looks like an attention getter. H^^
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
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Have fun as I have and I am still breaking a record.

Offline George Hostler

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Re: Cox 1/2A Product engine.
« Reply #23 on: December 13, 2018, 11:51:34 AM »
Seen one like that on one of the British FF fun fly meets.  Looks like an attention getter. H^^
But impractical where I'm at. We rarely have a calm windless day.

Online Larry Renger

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Re: Cox 1/2A Product engine.
« Reply #24 on: December 13, 2018, 02:24:11 PM »
I lost one of those in thermal ar Taft!
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

A closed mouth gathers no feet!

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #25 on: December 17, 2018, 09:18:27 AM »
The Cox conversation continues:

George: I had to grind down the heads of two of the screws for mounting the Sure Start (not enough clearance) on a firewall. Any other way of getting the mounting job done?

Dave: Good to hear that interchangeability is endemic in these mills. So is it possible for me to swap a single port older Babe Bee piston/cylinder with the double port Sure Start P/C? Maybe get a hopped up Bee out of the deal? Also, is there enough advantage to removing the central bars in the exhaust slits to justify the effort?

Comments much appreciated, good bros.

Dave Mo....

Offline john e. holliday

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Re: Cox 1/2A Product engine.
« Reply #26 on: December 17, 2018, 10:38:47 AM »
In my experience the slim bar in the exhaust port made no difference on my mouse racers.   That is as far as air speed.  I believe fuel economy was better by several laps with Golden Bee tanks.  Besides that bar keep my glow plug clip from getting in the port when pitting. D>K
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530

Have fun as I have and I am still breaking a record.

Offline goozgog

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Re: Cox 1/2A Product engine.
« Reply #27 on: December 17, 2018, 12:26:44 PM »
  Hey Dave, It's almost Christmas so if you need
a plastic " product" back plate with four mounting
holes, I can mail you one as a gift.
 Let me know if there are any other little parts
you might need, but I don't have spare Glow plugs
or reeds.

Cheers! - Keith

 
   
Keith Morgan

Offline George Hostler

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Re: Cox 1/2A Product engine.
« Reply #28 on: December 17, 2018, 01:05:57 PM »
I had to grind down the heads of two of the screws for mounting the Sure Start (not enough clearance) on a firewall. Any other way of getting the mounting job done?

Dave, on my Sure Starts and two 290 donors I received from a friend, the screws leave enough clearance that they don't touch the firewall. What screws does yours have? Mine have the factory Cox screws. I'm thinking that your engine has different screws on them.

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #29 on: December 18, 2018, 12:05:12 PM »
OK!

John the Good: Thanks for providing your experience regarding the bar exhaust - I'll leave it in place.

Keithmeister: Your generosity is showing! Many thanks for the offer. What I'd like to lay my hands on is one of the choke tubes because the needle valve could stand some support and the gent receiving the motor might find intake priming useful. Any insight on your Goozgog "handle"?

George: I think I have a standard Sure Start back plate and that I jumped the gun in my question. I just realized that standard socket head screws would work for mounting the beast to a firewall. The screws I ground down were the slotted round head models and were needed only on the two upper mounting holes with insufficient side clearance.

Lots of fun here.

Dave Mo...   


Offline goozgog

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Re: Cox 1/2A Product engine.
« Reply #30 on: December 18, 2018, 12:36:48 PM »
Hey Dave,

  I went digging through the Big Box of Cox
but I do not have any of  the gray plastic
choke tubes..  Sorry.
I guess it wasn't considered important when
these engine were salvaged from wrecks.

  I do have a lot of long needles and less long
needles. They all seem ridged enough that
vibration wouldn't be a problem, but I'm sure
you could support them with something.

   Just so you know, Floyd Carter and Bob
Zambelli have both been very generous
helping me with my Old Time Planes...
Now it's my turn to pay it forward, so
I will gladly look to see what I have for you.
Send me a PM here at Stunthanger and
let me know what you need.

   "Goozgog" is the radio call sign for my boat.
so when I first came online it was the natural choice
for a name. Handles seem unnecessary 20 year later.

Cheers! - Keith Morgan
Keith Morgan

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #31 on: December 18, 2018, 12:57:25 PM »
Dave Mo,

Glad you are making progress on your project!

The product engine backplate has clearance holes for number 4 screws. Using a smaller screw such as a #2 you might want to use a flat washer. A set of #2x1/2" screws are sufficient to hold the engine on.  (This is the standard size for the integral tank setups like a Babe Bee, Black Widow, etc. Their backplate holes are sized for #2's.)  The hex socket "wood" screws really are the easiest to deal with for installing and removing the engine. Lots less fumbling with the small parts. The Du-Bro part number for these is #381. I drill pilot holes to the thread root diameter to avoid damaging the firewall by forcing the screw into it. It is a lot nicer to install the screw the first time, too. To reduce the oil soaking, I like to mount the engine, then remove it and add a drop of CyA to each hole. It helps the plywood stand up better to the installation torque and adds some fuelproofing as well.

 Don't try to remove the bar in the exhaust port. You will inevitably end up with a burr on the inside of the cylinder that you have to remove or you will score and damage the piston, or you may ding the fit if you go inside with a Dremel or lap or....   On this one you have nothing to gain and everything to lose.

There is no issue with installing a twin bypass cylinder on an older Babe Bee. It will give more power but drink more fuel doing it. I recently ran three original Bees in a few oddball sport planes loaned to me for our 1/2A Fun Fly. They all produced good power and surprising airspeed on .008x35 lines. No line tension issues in that group!

The majority of Cox .049 parts are interchangeable. One exception is that some tanks are set up for the old-style wire reed retainer and some for the plastic cap style. So depending on which tank, or in the case of the plastic backplates, you have you will need to stay with that system. It affects which retainer you use, and whether you need a paper gasket, but not the reed itself, which is still interchangeable. Hope that makes sense.

Dave H.

Online Larry Renger

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Re: Cox 1/2A Product engine.
« Reply #32 on: December 18, 2018, 06:26:32 PM »
As a hopefully competent commentator, Dave is right on.
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

A closed mouth gathers no feet!

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #33 on: December 19, 2018, 09:00:03 AM »
Larry: With you vouching for Dave, it just doesn't get any better!

Dave: Besides sending the Sure Start on to the newcomer, I intend to mount the Babe Bee on a SIG 1/2A Skyray. Would like to leave the Bee at a stock power level for this application. Based on your experience, it should handle that model well enough given the same type of lines you use.

Keith: In the distant past, I spent some time in Turkey and Goozgog almost sounds like some kind of Turkish word! Coincidence?

Thanks for all the good will here.

Dave Mo...

Offline George Hostler

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Re: Cox 1/2A Product engine.
« Reply #34 on: December 19, 2018, 10:27:21 AM »
George: I think I have a standard Sure Start back plate and that I jumped the gun in my question. I just realized that standard socket head screws would work for mounting the beast to a firewall. The screws I ground down were the slotted round head models and were needed only on the two upper mounting holes with insufficient side clearance.

Back during a long gone era 4 decades ago, I'd drop by a local hobby store within 10 minutes of home and buy Dubro 2-56 screws with blind nut sets to mount Cox engines. The equivalent size in sheet metal screws would work, too, sometimes 3-48 (except for the Pee Wee's). I've seen such at Lowes home improvement, but are more costly if you can find them. I've found them on-line but the killer is shipping.

Not long ago I bought a set of screws in a plastic box, various sizes in a kit for RC cars. It had close metric diameter equivalents sheet metal screws and nylon insert nuts and machine screws. Yes, the larger head sizes on larger diameter screws like the #4's in pan head and not fillister or socket head have larger heads not suitable.

Offline john e. holliday

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Re: Cox 1/2A Product engine.
« Reply #35 on: December 19, 2018, 10:53:41 AM »
Hey George try RTL Fasteners.   Very reasonable especially with the bulk sizes.    D>K
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530

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Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #36 on: December 19, 2018, 03:07:55 PM »
Dave Mo,

For a  beginner, and for anyone who is not meticulously careful by nature, I would substitute Spectra material for the .008 stranded cable lines. A suitable brand and size is Power Pro 30 lb test (equivalent to 8 lb monofilament diameter) fishing line.  The stuff works great and is not easily damaged from handling like the steel cables. Do not try to use monofilament line--it is a totally different beast.

As I have probably mentioned too many times before, I have been using a Baby Skyray on .008x42 stranded lines as a beginners trainer. It has a large (1-1/2" dia.) fender washer for tip weight. It is running a product engine piston/cylinder on a Babe Bee. It will fly straight and level training laps in a pretty fair breeze. Since we ply over pavement I put a two-wheel landing gear on it by making a notched plywood spacer between the engine and the firewall. You could adapt a similar concept to a product engine installation. If your flying protégé is agile and maybe not super-prone to getting dizzy, then for a Skyray/Bee combination, I would use the Spectra and run anywhere from 35' to 40' lines. Less if you are having line tension issues; more if you are having dizzy issues and don't have much breeze. You can make up a set of Spectra lines right at the field in no time at all--especially if you have some experience with fishing gear!

All that said, if I had .008x42's all made up and a stock Babe Bee installed, I'd just be sure to install the huge fender washer (or equivalent weight) and get right to the training. It will work if you are not doing loops and such yet.

Dave H.

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #37 on: December 19, 2018, 08:05:05 PM »
Ah, Keith (or Dave H if you're reading):

You might be able to help me after all. My older Babe Bee has a metal tank, and I've had a deuce of a time keeping the fuel inlet pipe in place on the internal metal nipple. I fired up the motor again this eve numerous times and it ran for maybe 30 seconds, regardless of needle setting. Runs OK when I top off the tank, but quits again. My guess is that the fuel supply pipe is acting up. What do you use, and have you got anything like that on hand? When I look at online suppliers, I find what seem to me an odd assortment (aluminum pipes, brass pipes, plastic pipes, metal springs, the kitchen sink, etc.).

Dave...


Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #38 on: December 19, 2018, 08:16:49 PM »
Dave H:

Good call on the Spectra lines as I've already got a pair of 30 pounders at 40 feet. Really like them once I figured out how to prevent the knots from loosening.

Now for the little Skyray. I'll adopt your good suggestions on the tip weight and the landing gear. I'd like to mimic your engine setup as well. With the Babe Bee mod, I take it that the product motor cylinder has two intake ports. True? This would necessarily cut your gas mileage and air time. So, do you use the standard 5cc tank or the larger 8cc version? I suspect that a beginning flier is happy with short flights, no?

Dave Mo...

Online Larry Renger

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Re: Cox 1/2A Product engine.
« Reply #39 on: December 19, 2018, 08:55:01 PM »
My standard fuel pickup is as follows:

Anneal some 1/16” ID Aluminum tube. Insert some close fitting weed whacker line and bend to the desired shape, depending on the desired pickup location. Extract the line and trim the tube to fit. Angle cut the pickup end so it can’t seal against the backplate.

Use some silicone fuel hose to couple the tube to the backplate nipple.

Doesn’t age, doesn’t change position, better fuel flow than the plastic tube with internal spring. :D
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan

BTW, Dracula Sucks!

A closed mouth gathers no feet!

Offline George Hostler

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Re: Cox 1/2A Product engine.
« Reply #40 on: December 19, 2018, 09:58:04 PM »
Good advice, Larry. I've broken my share of tank back nipples attempting to remove the old hardened plastic fuel pick up. Seems that advice has permeated the Cox racing world. Paul Gilbeaut has a photo of what that looks like in his later article.

I've used a short length of silicon fuel line, but has a tendency to vibrate out of place.

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #41 on: December 20, 2018, 01:41:55 AM »
The solid pickup line has to have a good fitting silicone coupler. I have had these pop off the nipple during a Mouse race when the engine is really turning up. (Of course, that same plane/engine broke a Sullivan 4-40 clevis from vibration too.)  Otherwise, this is a good way to do it. I think Paul erred in his article where he called the standard Cox fuel line "neoprene."  Not sure what the Cox specification was, but probably something more like a vinyl-based polymer. They did use neoprene between a product engine backplate and the separate tank of some of the ready-to-flies I have seen.

If you want to use a plastic tubing setup, Cox International can set you up, but it is not the same as the original stuff. This looks like yellow Tygon, which should work as long as the ID and wall are the same. Check here:  https://coxengines.ca/cox-.049-fuel-tank-pick-up-line-3.html   Or, you can look at their original stock tune-up kits and see the real deal.

I would recommend a different location for the pickup end than what is shown in his photos to allow you to run to the last drop. I would put it below the centerline, not above (assuming his photos show the same upright needle that he always set up for Les Akre). Even for Mouse, the free surface of the fuel is inclined about 16 degrees from the vertical, so the pickup is not at the "last drop" position. For a slower sport plane it would be lower than that, but I like it to be above (laying on) the lower outboard tank screw.

All this talk about fuel pickup location reminds me that you might want to know the best way to shut down a Cox integral tank reedy. If you have the 8cc tank with over and under stunt venting, then just cover up both with your finger and thumb. If your tank does not have an air leak (very, very common) then it will lean out and shut off. If you have a backplate with the filler and vent right up against the needle, then the best way is to remember where exactly you placed the fuel pickup and tip the plane until it is at the top. This will be nose down and outboard wingtip up. Do not throw a rag into the prop. The crankshaft does not like this, and your prop might not either. Either may break sooner than it otherwise might. I also do not like the pitman trick that uses a wooden stick with a short piece of large tubing on it which is then pressed onto the spinner. Also hard on the crank and murder on the case and drive washer unless you have installed the steel washer used on the Killer Bee. And your need to do all of this goes way down if you use the non-contacting starter spring, and goes to zero if you use the ratchet/spring starter setup.

For an initial training plane, I think the smaller Babe Bee tank (5cc) works fine even with the twin bypass product motor cylinder. Plenty of laps for practice on 25% nitro fuel. And, it gives you more practice at takeoffs and landings which are important initial skills.

I agree with George about the vinyl tubing getting hard and causing problems. Bad enough on the metal backplates, but on the plastic ones if you do not shave off the tubing carefully, you will snap off the nipple.  A bit unexpected when you note that the nipple on the plastic backplate does not even have a hose barb. Breaking it off is a bummer when all you want to do is fill the tank and fly some more....

I'd like to thank Larry for the string trimmer tip for bending that little tubing. That sounds easier than what I did.

Divot

Offline Wayne Collier

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Re: Cox 1/2A Product engine.
« Reply #42 on: December 22, 2018, 02:55:46 AM »
And here I've been shutting mine off by pinching the spinner with my finger and thumb  ...
Wayne Collier     Back in Northeast Texas
<><

never confuse patience with slowness
never confuse motion with progress

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #43 on: December 22, 2018, 01:13:44 PM »
Wayne,

If that works for you....

By the by, for those who like pinching:  be aware that the undercut on the crankshaft that provides machining relief for the prop driver knurling is in pretty much the same place that the standard spinner/bolt ends. Which is where a lot of the cranks fail. If you like pinching (or rags, or ....) then you might want to install the stud and bottom it out, perhaps with some blue Loctite. Then use a nut or spinner nut instead. I have found it difficult to install a prop drive washer after the end of the crank breaks off....

Divot

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #44 on: January 10, 2019, 11:16:56 AM »
Hello All:

I just finished fashioning a pickup tube from brass a la Paul Gibeault. Very pleased with my work, but(!) it doesn't fit the 5cc tank I've got in mind. I just sent off an order for a new tube via our Cox supplier. Great idea from Paul, though.

Thanks.

Dave Mo...

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #45 on: January 10, 2019, 02:26:58 PM »
What trouble are you having making it fit, Dave?

Divot

Offline bob whitney

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Re: Cox 1/2A Product engine.
« Reply #46 on: January 10, 2019, 07:01:22 PM »
5 c.c. would be the baby bee tank, not a lot of room for a brass tube
rad racer

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #47 on: January 10, 2019, 07:40:39 PM »
Yup, Bob, 'tis a Babe Bee that I'm passing on to a new flier. All I want is for the thing to run a full tank.

Dave: Using Paul's technique on even the tiny tube won't allow for a small enough radius in the bend for the tube to clear the front of the shallow tank. His illustration shows the tube standing nice a proud on the end of the nipple and secured by fuel line. Beautiful! But placing that setup in a 5cc tank would just end up mashing the whole thing down for lack of room. I can't figure any way around it short of putting a kink in the pipe.

Dave Mo...

Online Dave Hull

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Re: Cox 1/2A Product engine.
« Reply #48 on: January 10, 2019, 07:54:45 PM »
Ok. I understand the issue now. I have only used the metal u-bend on the larger tanks. Going back to the vinyl tubing approach makes sense.
Good luck!

Divot

Offline Dave Moritz

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Re: Cox 1/2A Product engine.
« Reply #49 on: January 19, 2019, 01:22:41 PM »
Divot (or anyone else in the know):

I laid my mitts on a vinyl tubing setup from the EX (Cox) folks for the Babe Bee. It came with a skinny spring about one inch in length. I take it that this fine little critter is placed inside the pickup tube? Does it need to be worked into the nipple as well? Not sure why it's even needed.

Any relevant enlightenment out there?

Dave Mo...


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