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Cox Engine of The Month
November-2017
MauricioB's

"Cox Tee Dee .010"



PAST WINNERS
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Blank TD .049 Cylinder

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Blank TD .049 Cylinder

Post  1/2A Nut on Sun Apr 09, 2017 5:20 am

Blank TD .049 Cylinder

I have a blank TD .049 cylinder from 40 ish yrs. ago taper cylinder type.
Looking at using it, I may drill and tap it for 5mm and screw in a header
tube for use a .8cc Profi pipe.

Who has ground in flutes or extra ports? I am looking at recommendations
of what method would be best. I may just clamp the cylinder down on the drill
press and set the press depth and simply grind in the transfer ports. Perhaps 3 ports.
Exhaust port is facing to the rear so two transfer ports on the side at a minimum.

The last pic is a mod Dale Kirn would do to blank cylinders as I understand to
increase max mix into the combustion chamber. It would feed air and fuel all the
way to the top of the exhaust port for max intake. The other diagram shows
my mod idea for a screw in header pipe leak free as the threads will have high
temp Loctite applied.

Flow from the tuned pipe will be evenly distributed, the pipe acts like a pump
and will force it's charge in thru the short 4mm ID header section made from steel.
MRP (mean reflection point) will be 7.5" For best performance at 33,400 rpm.
Lil speedy gets 30.49k with no tuned pipe 4.1x4.1N prop 117mph. I hope to do the
better at 33.4k / 135mph with the lower weight HQ Carbon 4x4.5 / 5.8oz RTF plane.

Timing is a crap shoot as the thicker steel band around the blank cylinder controls the
limits of the header tube diameter. My guess I will only increase timing from 140 degs.
to 150 ish. Lastly a vid of what's possible currently with the Profi pipe at stock timing
4x2.5 ID square header pipe.

Any good input on the task at hand please feel free to chime in.

Small Cox Logo











Published on Aug 3, 2016

Cox TD .050 / Profi Tuned Pipe / 25,193 Static - HQ Prop 4 x 4.5
Static 7.3 oz thrust / .132 hp / 99w / 107.3 mph /
9.3in MRP / 140 deg timing / Pipe set for 25,215 rpm!
Fuel line was a bit big for 1/2A use / pressure line was correct.
For flight prop HQ Prop 5x4.5 will unload near MRP and produce
est. 11 oz thrust. Non SPI / 20% oil / 30% nitro.

The above is already great for static but I want a leak free system
without the use of a ringed header pipe system around the cylinder.

Small Cox Logo
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Re: Blank TD .049 Cylinder

Post  Ken Cook on Sun Apr 09, 2017 5:35 am

You don't have a lot of threaded area in the cylinder to hold the pipe. Anytime I've seen this mod, it also had some form of nut or adapter brazed to the cylinder. I believe it was in the 1980 Model Aviation featuring the Dale Kirn Spullet, he mentions the mods that were done in regards to what your looking for. I have that magazine and I've been meaning to dig it out.
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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Sun Apr 09, 2017 10:59 am

That would be great! Thank you Ken!! Small Cox Logo

I found these pics on another forum the guy said he knew Dale
and was helped with the pipe setup. He said he would open it
up and show the engine but has not as of yet posted any new pics.

http://www.intlwaters.com/index.php?showtopic=71801&page=2

From the author Carl Noki age 63:
The motor (i have 7 of them) are all set up with the standard (now days) 3 intake and a single exhaust.
The cylinder adapter is a home made one that clamps tightly around the cyl wall. Dale Kirn and I worked
and built the motors back in the mid 70's when I was stationed out at Castle AFB in CA.
As for speed, it is a constant 97mph on old school fuel. ( 70%N, 15% Castor, 10% Alky, 5% Prope)


Quote from a responder to the thread:

Years ago my flying partner, B. B. Brown, had some Cox cylinders that had not been machined for the intake and exhaust ports. He also had a pipe header that was hand made to fit the cylinder for a single exhaust port. You would typically cut 3 intake ports and one exhaust port for a piped engine








Last edited by 1/2A Nut on Sun Apr 09, 2017 4:42 pm; edited 3 times in total
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Re: Blank TD .049 Cylinder

Post  fredvon4 on Sun Apr 09, 2017 11:22 am

A few years back I though I might like to take the rather wavy, machining marks, of the ports inside the cylinder--- and smooth / polish them

I can tell you the small cutters from Dremel do NOT work
I had a tough time keeping a small diameter polishing impregnated rubber tool IN THE port slot ( I did not to widen...just smooth)...not matter what RPM

Obviously I do not have a precision Mill, and I know my drill press has too much run out to attempt so I focused on trying to use the Dremel..... Failure!!

I was experimenting with 2 damaged (pliers marked) cylinders and found they are made from very hard metal...well harder than the Dremel bits

If I was serious about cutting in the ports I would enlist one of the several expert machinists on Stunt Hanger... try Motorman first as he seem to like one of a kind projects

When the through hole for the Pipe is cut ...I know you know this... the interior cylinder needs to be de-burred....

I suspect, due to how hard I think these are, you will find cutting threads a royal pain

IF I had small but very precision tooling I would love to change some ports a slight bit for the tach race engines...a schoche deeper and maybe a few thou taller
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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Sun Apr 09, 2017 11:59 am

Yes that is my worries with a dremel tool. I have some good quality fine files could manually
create the transfer ports would be a slow safe way to monitor. I would prefer a more sure shot way
of grinding them in evenly with consistency in lieu of no lathe to play with. Can use an old cylinder
to practice cutting in ports till I am happy with the consistency.

Perhaps diamond bits will hold up to the abuse. The last pic shows a typical metal bit that could
be troublesome to control. Looking at getting one of these can just monitor and feather in the
ports: 2 WAY 3" DRILL PRESS X-Y COMPOUND VISE CROSS SLIDE MILL







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Re: Blank TD .049 Cylinder

Post  Mike1484 on Sun Apr 09, 2017 4:13 pm

Why not try Bob Mattes . He reworks Tee Dee .020 's for the free flight guys .

Mike 1484
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Re: Blank TD .049 Cylinder

Post  Mike1484 on Sun Apr 09, 2017 4:18 pm

That cross slide vice is not a very precise way of doing any machine work . Good for making scrap parts or locating a point to start a center drill but not for milling .

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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Sun Apr 09, 2017 4:28 pm

Yes I figured the vise would be better than me trying a diamond bit with a dremel and doing it by hand.
I could at least have better control over the heating part as it is processed. I know a machinist could knock
this out with ease with a lathe. I would much rather find a solution surly there is a way without too much
fuss.




049 cl speed flight / Alex Osovik

   Published on May 7, 2015
This is a .049cc control line speed model . After a few attempts we got a ready for contests model .
It powered by Profi 049cc engine. It is probably smallest in the world control line speed event.
See more Profi Micro Engines:
  http://profimicroengine.hol.es/enmenu/


This was neat..



Published on Apr 26, 2016
PROFI Micro Engines group just made V8 glow engine only 4cc total.
Each cylinder 0.5cc. RPM about 10,000.
See more engines http://profimicroengines.com/
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Re: Blank TD .049 Cylinder

Post  pkrankow on Sun Apr 09, 2017 5:46 pm

You could cut a bee case in two so you can hold the part by its threads...

Alternately use a glow head or head clamp.  

Better still - both.  Well supported in semi-custom fixture will prevent warping.

reportedly the cylinder is just "mild" steel so nothing exotic and rather machinable.
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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Mon Apr 10, 2017 2:46 pm

Yes good suggestions let the old parts take the brunt of the vise.
I will post some progress pics when I am ready to commence
modifying the cylinder for a tuned pipe. Need to buy a few items
to do the job yet.
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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Mon Apr 10, 2017 7:49 pm

The power and influence of Kirn Kraft to this day:

1 little part has hit $45.44  Shocked
such a small part only 1.95 shipping.

http://www.ebay.com/itm/272617456403?_trksid=p2060353.m1431.l2649&ssPageName=STRK%3AMEBIDX%3AIT



I bought my first one back in 1987 own 2 and decided to put a bid in at 17 bucks the cost is gone
wayyyy to high to even think about a bid now lol.
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Re: Blank TD .049 Cylinder

Post  fit90 on Tue Apr 11, 2017 8:08 am

Aren't these still available from Texas Timers? If they are then I bet you can get them for a lot less.
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Re: Blank TD .049 Cylinder

Post  fredvon4 on Tue Apr 11, 2017 8:39 am

Just looked and glad I got several a few years back...I think for $15 each

TT has then now for $35
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Re: Blank TD .049 Cylinder

Post  fit90 on Tue Apr 11, 2017 10:37 am

fredvon4 wrote:Just looked and glad I got several a few years back...I think for $15 each

TT has then now for $35

WOW!! I guess 1/2A isn't nearly as cheap as it used to be!
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Re: Blank TD .049 Cylinder

Post  roddie on Tue Apr 11, 2017 12:26 pm

I bought this die-grinder over 30 years ago from "Snap-On". I have zero-experience with cylinder-porting. Just throwing this out there...




It's obviously too big in diameter for Cox .049 cylinder-porting.. but the profile looks interesting. Maybe you could research smaller-sizes? As mentioned.. it's the fixturing that needs to be dead-accurate.
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Re: Blank TD .049 Cylinder

Post  fredvon4 on Tue Apr 11, 2017 12:44 pm

I have done a fair amount of porting and polishing on Iron and aluminum heads.... Aluminum had it's own touch with a 20,000 RPM tool vs same tool in a Cast iron head... neither fun or easy.... I like to think I did good but the few times I invested in a professional job I could see I had NO CLUE!!! grin

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Re: Blank TD .049 Cylinder

Post  Ken Cook on Tue Apr 11, 2017 3:26 pm

I found the article from Model Aviation. Unfortunately, this isn't the article with the detailed cylinder info. Lots of detail on the construction and flying but nothing engine related. I saved this mag because I always wanted to build the plane. Obviously, I have another article in which I need to find in another magazine. I used to place sticky notes on them so I could find them again. What I do have though is a rear exhaust TD cylinder. Mine is ported like you mentioned. I don't know if this is of any value to you. I could send pictures or maybe this is something that I could send therefore it would need to be returned.
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Re: Blank TD .049 Cylinder

Post  GallopingGhostler on Tue Apr 11, 2017 7:35 pm

7 years ago I downloaded a PDF of 2 articles written by Larry Renger. Where I got it I don't know. Model Aviation articles were titled Cox 1/2 A Engines: Part I of II, Background (June 1996 MA, Pages 11 - 14) and Part II of II, Care and Feeding (July 1996 MA, Pages 35-40, 43). File is 2.9mb. Part I shows photos of and explains porting, has a table of what models and years got what ports, exhaust slit type, etc. Between articles is a 1 page ad of Cox engines.

File is 2.9mb. I can E-mail file if someone PM's their E-mail address.

On this forum is a compendium that also has cylinder bypass port info.

https://www.coxengineforum.com/h31-cox-history

I don't know if there are any articles that give specific machinist dimensions on bypass port dimension details and locations.

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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Tue Apr 11, 2017 8:53 pm

Thank you guys for your inputs and Ken for looking for the magazine article.

Ken I have seen photos of your header design and the associated thread but
there was no testing information or on pipe type used, timing and porting etc.

As the piston comes back up and the transfer ports are closed off the window
for induction from the pipe begins. I need to watch just how high up the transfer
ports go. Unlike Dales version in the diagram he was working with no pipe pressure.
So naturally it's best to extend the transfer ports to start feeding the combustion chamber
as soon as possible.

The tuned pipe acts like a pump and will aid in assisting a stronger draw of
fuel and air through the venturi allowing for lowering the height of the ports per my
first diagram providing a longer gate time for the pipe to feed. I would at least 160 deg.
over the stock 140. Another important addition is having the room for a 3rd transfer port.

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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Tue Apr 11, 2017 10:48 pm

I have a response with some good numbers to know / remember Dale Kirn and Carl sat down
and hacked this design out per the CL plane pics shown in this thread:

"Sent Today, 08:59 PM
will try to take a few pics this week of the manifold assembly on teh motor.
I will not be taking it off the cylinder as it is a pain to properly install and get everything lined up perfectly.

my cylinders are of the 3 intake porting variety. and a single exhaust. I run 178 deg. on exhaust and 125 on boost port and 127 on the transfer ports.  head clearance depends on teh prop and the nitro I am running.

Carl"
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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Thu Apr 13, 2017 3:10 pm

Received a custom piston, the skirt has been cut down and thinned.
Should add 1k rpm + and reduce load on the connecting rod / ball socket.

2.8g vs stock 3.2g

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Re: Blank TD .049 Cylinder

Post  GallopingGhostler on Thu Apr 13, 2017 3:41 pm

Special piston / rod set is a nice NOS item, 1/2A Nut. Lightweight & increased SPI, really nice.

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Re: Blank TD .049 Cylinder

Post  fit90 on Thu Apr 13, 2017 4:24 pm

I have a cylinder blank if you want it. I am unable to pm or email so just pm me and let me know. Hopefully it will come through.

Bob
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Re: Blank TD .049 Cylinder

Post  1/2A Nut on Thu Apr 13, 2017 7:35 pm

Thank you Bob, PM sent.
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Re: Blank TD .049 Cylinder

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