News:



  • April 13, 2021, 09:12:34 PM

Login with username, password and session length

Author Topic: Cox 1/2A engine question  (Read 9296 times)

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Cox 1/2A engine question
« on: August 25, 2013, 04:54:34 PM »
My DO 335 needs a tad more power.   Has anyone tried the TD look alike piston set sold by http://coxengines.ca?  I guess it is out of the question to find new TD .051 piston/jug sets.
  
http://coxengines.ca/cox-.049-tee-dee-cylinder-and-piston.html

I plan to check out the LHS for high nitro fuel.  Probably 25% nitro.  I assume Caster oil content is important for cox engines. If all I can find is synthetic fuel how much Caster do I add per gallon?

Question:  who sells a good NVA assembly for the TD.  I am looking for a micro set needle assembly.  I plan to run on suction.  I don't need a pylon race engine.  Just a really strong 1/2A.

I guess this begs the question:  What is the best (strongest) 1/2A engine on the market today?

Thanks all for good advice   H^^

John RIST


John Rist
AMA 56277


Advertise Here

Offline Ron Cribbs

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 332
Re: Cox 1/2A engine question
« Reply #1 on: August 25, 2013, 05:26:37 PM »
My DO 335 needs a tad more power.   Has anyone tried the TD look alike piston set sold by http://coxengines.ca?  I guess it is out of the question to find new TD .051 piston/jug sets.
  
http://coxengines.ca/cox-.049-tee-dee-cylinder-and-piston.html

I plan to check out the LHS for high nitro fuel.  Probably 25% nitro.  I assume Caster oil content is important for cox engines. If all I can find is synthetic fuel how much Caster do I add per gallon?

Question:  who sells a good NVA assembly for the TD.  I am looking for a micro set needle assembly.  I plan to run on suction.  I don't need a pylon race engine.  Just a really strong 1/2A.

I guess this begs the question:  What is the best (strongest) 1/2A engine on the market today?

Thanks all for good advice   H^^

John RIST




John,

I have experience with the Cox international TD style cylinder and it performs well. I used it on a tach race engine last year and I had it turn over 20K on a reed valve.

For fuel 25% nitro is fine. Oil around 20% with half of that being castor. If you buy off the shelf fuel make sure the oil content is low so you can add pure castor to bring it up to 20%

Texas Timers sells a nice fine thread needle valve. Keep in mind the TD does not do real well on suction, but if you buy the Texas Timers fine thread NVA you can always switch to pressure bladder.

The most bang for your buck is probably the Norvel .049.

Good Luck!

Ron

Offline Larry Renger

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3842
Re: Cox 1/2A engine question
« Reply #2 on: August 25, 2013, 06:00:24 PM »
If you are flying scale, just drill out the venturi the next drill size. As I recall, the Venom venturi is.087" diameter. And if you have the screen over the venturi, get rid of it.

Also, what props are you running?
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 John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #3 on: August 25, 2013, 07:46:31 PM »
John,

The most bang for your buck is probably the Norvel .049.

Good Luck!

Ron

Ron who sells Norvel?
John Rist
AMA 56277

Offline Ron Cribbs

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 332
Re: Cox 1/2A engine question
« Reply #4 on: August 25, 2013, 07:58:14 PM »
Do a search for NV engines.

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #5 on: August 25, 2013, 08:35:57 PM »
And the Norvel(NV) Big mig .061 is considered 1/2A these days. It's an absolutely awesome screamer and runs great on suction. Do NOT follow their break-in instructions. If you get one, come back here and ask about the first runs before you crank it. Their instructions are designed to reduce phone calls and e-mails from people who can't get their new engines to crank. And what they'll have you do to loosen it up before your first crank will damage your compression for life.

Rusty

EDIT: And order a starter spring with it too.
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #6 on: August 27, 2013, 08:38:28 PM »
Well I found some 33% nitro fuel at the LHS.  It is Traxxis brand car racing fuel.  As best I can found out it has 16% oil.  I could not find out if it has any caster content.  Per A call to Traxxis teck support it has 16% oil but they will not tell me what type of oil.  Any way I plan to add 3.6 oz of caster to the qt. of fuel.  According to Eric Perez's fuel calculator I will have 29.7% nitro, 25% oil, and 45.3% Mthnl.  I looked through my 1/2A parts box and I found a .051 TD jug set and a .049 TD jug set.  I plan to put the .051 on the front and the .049 on the back.

Next I plan to run the 15% fuel I have used in the past and check RPMs  front and back.  Next add the 30% nitro fuel and check RPMs front and back.  Next add the TD jugs and check RPMs one last time.  Will post results.

Now about props?  I am currently running a Cox 5x3 3-bladed on the front. I am running a Cox 5x3 3-blade pusher on the back.  I am using these because they are scale looking.  The full size DO-335 has 3-bladed props.  However for flight I can run any prop on the front. The back is limited to a pusher props.

What is a good prop for the front TD running on 30% nitro?
John Rist
AMA 56277

Offline Doug Burright

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 188
  • Legacy, Brodak kit
Re: Cox 1/2A engine question
« Reply #7 on: August 28, 2013, 02:13:18 AM »
I just have to pop in and say that I am running a Tee Dee .051, quite a lot lately, and it runs extremely well on just suction. Very steady, too! The prop is a black, Cox 5x3, but it does well on Master Airscrew 6x3 props, cut in increments to 5 inches, also. Perhaps fuel tank position is the factor, to achieve great performance on the engine, without going to some kind of pressure. Mine works great in an R/C Baby Birdie.

Do some experimenting - that will show you what works for you. Also, CASTOR OIL is mandatory for the Cox line of engines, as my experience has shown.
I will build it. It's gonna be really difficult to find me with an ARF. I know every bit of my airplane!

Offline Kevin Ferguson

  • Trade Count: (0)
  • New Pilot
  • *
  • Posts: 18
Re: Cox 1/2A engine question
« Reply #8 on: August 28, 2013, 08:08:54 AM »
The TD has a large Venturi so has limited depression (AKA signal) at the jets.  This makes it fussy re tank height.

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #9 on: August 28, 2013, 09:59:43 AM »
The TD has a large Venturi so has limited depression (AKA signal) at the jets.  This makes it fussy re tank height.
And if you want to run it on a small diameter pressure bladder, you can bore it out and it'll run a lot better. About .140" is the widely accepted best size. If you aren't sure if a venturi has been bored, try to drop the butt end of a 1/8" drill bit through it. If it won't go, it's stock size. Once I started using bladders on 1/2A, I never considered going back to a tank.
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #10 on: August 28, 2013, 06:01:23 PM »
And if you want to run it on a small diameter pressure bladder, you can bore it out and it'll run a lot better. About .140" is the widely accepted best size. If you aren't sure if a venturi has been bored, try to drop the butt end of a 1/8" drill bit through it. If it won't go, it's stock size. Once I started using bladders on 1/2A, I never considered going back to a tank.
Rusty

Right now I am using a balloon tank which, I am sure, is different then a bladder tank.  Is there a good how-to on bladder tanks.  I would like to try one.
John Rist
AMA 56277

Offline Ron Cribbs

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 332
Re: Cox 1/2A engine question
« Reply #11 on: August 28, 2013, 10:03:03 PM »
John,

Here is a link to a "how to" by ol Rusty himself. It can be found on the Cox Engine forum.

http://www.coxengineforum.com/t3317-pressure-bladder-how-to-videos-parts-one-and-two

Moderator: I am not sure if it's proper etiquette to post a link to another forum, if it's a faux pas please feel free to remove it with my sincere apology.

Ron

Jim Roselle

  • Guest
  • Trade Count: (0)
Re: Cox 1/2A engine question
« Reply #12 on: August 28, 2013, 10:05:24 PM »
John,

Here is a link to a "how to" by ol Rusty himself. It can be found on the Cox Engine forum.

http://www.coxengineforum.com/t3317-pressure-bladder-how-to-videos-parts-one-and-two

Moderator: I am not sure if it's proper etiquette to post a link to another forum, if it's a faux pas please feel free to remove it with my sincere apology.

Ron
That's where I learned about bladders and I will never go back to tanks.

Jim

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #13 on: August 28, 2013, 10:41:25 PM »
John,

Here is a link to a "how to" by ol Rusty himself. It can be found on the Cox Engine forum.

http://www.coxengineforum.com/t3317-pressure-bladder-how-to-videos-parts-one-and-two

Moderator: I am not sure if it's proper etiquette to post a link to another forum, if it's a faux pas please feel free to remove it with my sincere apology.

Ron
I did post that, thanks for endorsing it, Ron.

Please keep in mind that when I made that video, I had not been making bladders for very long. And as I frequently do, I made it look over complicated. Now days, I just tie a knot in the tube rather than plugging it, then cut off an inch and a half and use a soft wire as a twist tie on the front end to secure it to the Texas Timers cone shaped fitting.  All that tying in the video can be maddening.

I like the TT fitting because if there is a small air bubble in the bladder it won't easily get sucked into the line until it's almost empty. In fact, when I fill the bladder, I don't evacuate the air and it gives me a full lap of warning to stop acting crazy and fly flat.

The sister video, cranking with a bladder is better. I'd like to add one bit of advice. When you're cranking an engine and you don't know the needle setting, go rich and start from there. When the engine cranks, if it starts to shut off from too much flow, pinch the line to lean it back out and keep it running while you lean out the needle. Keeping it running bit by bit like this allows you to sneak up on the right setting to keep it running. Now that you know your needle setting, leave it there, even between flights, and you'll always have a quick starter. You'll fumble the first few times and drench the engine, but you'll get the hang of it and love it.

Here are the links to the youtube videos. The posts Ron linked you to have some good input from others if you wish to read the threads.





Hope this helps,
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #14 on: August 28, 2013, 10:49:02 PM »
John,

Here is a link to a "how to" by ol Rusty himself. It can be found on the Cox Engine forum.

http://www.coxengineforum.com/t3317-pressure-bladder-how-to-videos-parts-one-and-two

Moderator: I am not sure if it's proper etiquette to post a link to another forum, if it's a faux pas please feel free to remove it with my sincere apology.

Ron

Watched the videos.  It looks like the way to go. Thanks!
John Rist
AMA 56277

Offline Phil Krankowski

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1031
Re: Cox 1/2A engine question
« Reply #15 on: August 29, 2013, 08:46:07 AM »
Texas Timers has everything you need for bladder, including the NVA.

http://www.texastimers.com/

I built a set like they describe with the Tee, but seeing the inline set with the check valve on one end of the bladder, and straight feed to the engine looks a lot cleaner.

Minnesota Modeler shows the in-line setup, but they do not have the fine NVA
http://minnesotamodeler.webs.com/accessories.htm

Use at least 1 1/2 inches of bladder so you can load up more than 1/2 oz and not have an over-full bladder (which makes for a lean run with power loss)

I run Sig Champion 25%.  Shipping is reasonable if you order a bunch of quarts.

Phil


Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #16 on: August 29, 2013, 09:35:42 AM »
Rusty,

What is a good source for a plastic Hemostat.  All Tower and LHS has in metal.
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #17 on: August 29, 2013, 10:09:18 AM »
I'm lucky to have had a free source in the past. But I found these on the Bay. Looks like the same thing. :

http://www.ebay.com/itm/Hemostat-Plastic-Line-Tube-Clamp-Lot-Of-5-/120507296622?pt=LH_DefaultDomain_0&hash=item1c0ecb6b6e

I think you get 5 for that price.

Others use all sorts of clamping methods. Phil uses metal slide clamps that stay on the line. It's a matter of preference.
And I run my fuel line over the top of the fuse so it's easy to get a thumb on it if I have to fiddle with the needle.

I used to hide the bladder under the wing for the sake of aesthetics. But I'm over that now, and this works better for me.
 

Damn, she ain't quite as pretty as she used to be. ;D
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #18 on: August 29, 2013, 10:23:47 AM »
I'm lucky to have had a free source in the past. But I found these on the Bay. Looks like the same thing. :

http://www.ebay.com/itm/Hemostat-Plastic-Line-Tube-Clamp-Lot-Of-5-/120507296622?pt=LH_DefaultDomain_0&hash=item1c0ecb6b6e

I think you get 5 for that price.

Thanks! eBay is my friend for anything odd.  Clamps on order. #^
John Rist
AMA 56277

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #19 on: August 29, 2013, 10:34:45 AM »
Well I found some 33% nitro fuel at the LHS.  It is Traxxis brand car racing fuel.  As best I can found out it has 16% oil.  I could not find out if it has any caster content.  Per A call to Traxxis teck support it has 16% oil but they will not tell me what type of oil.  Any way I plan to add 3.6 oz of caster to the qt. of fuel.  According to Eric Perez's fuel calculator I will have 29.7% nitro, 25% oil, and 45.3% Mthnl.  I looked through my 1/2A parts box and I found a .051 TD jug set and a .049 TD jug set.  I plan to put the .051 on the front and the .049 on the back.

Next I plan to run the 15% fuel I have used in the past and check RPMs  front and back.  Next add the 30% nitro fuel and check RPMs front and back.  Next add the TD jugs and check RPMs one last time.  Will post results.



Well I have done the 15% and 30% nitro test:

Front:  15% = 15640rpm,  30% = 26320rpm
Back:  15% = 12940rpm,   30% = 18280rpm

At this point I don't plan to try TD jugs.  I don't have any in really good shape and the product engine jugs are dual port and seem really strong.

As soon as my .008 set of lines come in I will do a test flight.  Hopefully all will be good and no further fixes needed.

O yes one more point - the rear engine still has the intake screen in place.  I could remove it.

 n~   #^   #^
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #20 on: August 29, 2013, 11:09:52 AM »
Well I have done the 15% and 30% nitro test:

Front:  15% = 15640rpm,  30% = 26320rpm
Back:  15% = 12940rpm,   30% = 18280rpm

At this point I don't plan to try TD jugs.  I don't have any in really good shape and the product engine jugs are dual port and seem really strong.

As soon as my .008 set of lines come in I will do a test flight.  Hopefully all will be good and no further fixes needed.

O yes one more point - the rear engine still has the intake screen in place.  I could remove it.

 n~   #^   #^

Screens are good protection. I run them on my bored venturis too.

Bernie's jugs are great. ::) I don't doubt they'll run as well as the old Cox #4s. My main TD fuel is 25%. I tried 35% but the difference isn't enough to justify the extra wear and tear. 20% is fine too. Why the difference in RPMs, are you using a different prop on each end? BTW, 26k is crank busting RPMs. Sounds like APC prop numbers. You might want to keep it at or less less than 23k. No other brand will turn as fast as an APC. Most people here probably disagree, but I like to get Master Airscrew GF-series 6x3s and cut them to anywhere between 5 and 5.5" depending on my needs. At those high RPM, they should be balanced. 220 sandpaper glued to a glass pane is my method of lightening the back of one blade. If the hub won't balance, I don't worry about it.
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline Phil Krankowski

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1031
Re: Cox 1/2A engine question
« Reply #21 on: August 29, 2013, 04:31:29 PM »
I'm using a plastic clip from HK

http://www.hobbyking.com/hobbyking/store/__7673__Fuel_Line_Stopper.html

http://www.servimg.com/image_preview.php?i=44&u=17848739

I need to restrain my fuel lines better and put the bladder in a sack.  I am thinking a screw through the clip instead of a rubber band and  a wire tie over the Tee.

That metal clip Minnesota modeler has looks like a treat.

Phil

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #22 on: August 29, 2013, 04:44:09 PM »
Screens are good protection. I run them on my bored venturis too.

Bernie's jugs are great. ::) I don't doubt they'll run as well as the old Cox #4s. My main TD fuel is 25%. I tried 35% but the difference isn't enough to justify the extra wear and tear. 20% is fine too. Why the difference in RPMs, are you using a different prop on each end? BTW, 26k is crank busting RPMs. Sounds like APC prop numbers. You might want to keep it at or less less than 23k. No other brand will turn as fast as an APC. Most people here probably disagree, but I like to get Master Airscrew GF-series 6x3s and cut them to anywhere between 5 and 5.5" depending on my needs. At those high RPM, they should be balanced. 220 sandpaper glued to a glass pane is my method of lightening the back of one blade. If the hub won't balance, I don't worry about it.

I am currently running a Cox 5x3 3-bladed on the front. I am running a Cox 5x3 3-blade pusher on the back. The back has a heavy load of U-joint and shaft.  See photo.

I could run a 2-bladed prop on the front to load it down.  What would be a good size.  I guess another option is to richen it up a tad.
All advice appreciated - Thanks in advance.
John Rist
AMA 56277

Jim Roselle

  • Guest
  • Trade Count: (0)
Re: Cox 1/2A engine question
« Reply #23 on: August 29, 2013, 05:02:10 PM »
I am currently running a Cox 5x3 3-bladed on the front. I am running a Cox 5x3 3-blade pusher on the back. The back has a heavy load of U-joint and shaft.  See photo.

I could run a 2-bladed prop on the front to load it down.  What would be a good size.  I guess another option is to richen it up a tad.
All advice appreciated - Thanks in advance.

That model is awesome! Do you have any flight video?

Jim

Offline Kevin Ferguson

  • Trade Count: (0)
  • New Pilot
  • *
  • Posts: 18
Re: Cox 1/2A engine question
« Reply #24 on: August 29, 2013, 05:32:18 PM »
Rusty,

What is a good source for a plastic Hemostat.  All Tower and LHS has in metal.
Most CL modelers end up with a surplus of very sevicable fuel line clamps:
Fuel off:

Fuel on:


Works on both Full size and 1/2A line.

If you screw the other end down to model it is easier to work with one hand.

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #25 on: August 29, 2013, 05:39:05 PM »
That model is awesome! Do you have any flight video?

Jim

No not yet.
John Rist
AMA 56277

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #26 on: August 29, 2013, 05:47:57 PM »
Screens are good protection. I run them on my bored venturis too.

Bernie's jugs are great. ::) I don't doubt they'll run as well as the old Cox #4s. My main TD fuel is 25%. I tried 35% but the difference isn't enough to justify the extra wear and tear. 20% is fine too. Why the difference in RPMs, are you using a different prop on each end? BTW, 26k is crank busting RPMs. Sounds like APC prop numbers. You might want to keep it at or less less than 23k. No other brand will turn as fast as an APC. Most people here probably disagree, but I like to get Master Airscrew GF-series 6x3s and cut them to anywhere between 5 and 5.5" depending on my needs. At those high RPM, they should be balanced. 220 sandpaper glued to a glass pane is my method of lightening the back of one blade. If the hub won't balance, I don't worry about it.

Well the dirty little secrete is out - I don't know what I am talking about!  mw~  I rechecked the RPMs on front and back.  The true reading on the front is 18500. The true reading on the back is 13500.  I am guessing that I had the tack set for 2 blade instead of 3 blade.  Anyway all is good.  I will test fly the 30% nitro tomorrow - hopefully the extra umph of the 30% will get me where I need to be.

You know I knew better. It didn't sound like 26K.  n1
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #27 on: August 29, 2013, 07:02:32 PM »
... hopefully the extra umph of the 30% will get me where I need to be.

You know I knew better. It didn't sound like 26K.  n1
Have you bored your venturi? Like I mentioned above, .140" works great. That's of course a 9/64 drill bit, and polish it a little with some fine sandpaper. 600 to 100 grit is fine. I wrap it on the pointed end of a bamboo grilling skewer. As for the screen, pop it out when you drill it out. Then form it into a slight dome on your pinky or whatever works for you, place it into the venturi and pop it back inverted and it'll usually seat in its groove.

EDIT: Oops, Oh wait, you're still running on suction aren't you. Duh!
Don't bore it yet then. nevermind
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline Phil Krankowski

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1031
Re: Cox 1/2A engine question
« Reply #28 on: August 29, 2013, 07:53:52 PM »
Would running 2 engines off the same bladder cause a royal mess?
Phil

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #29 on: August 29, 2013, 08:22:00 PM »
Would running 2 engines off the same bladder cause a royal mess?
Phil
Seems like it would work fine. Use a decent diameter Tee right out of the bladder.
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #30 on: August 29, 2013, 08:51:25 PM »
Would running 2 engines off the same bladder cause a royal mess?
Phil

I am guessing that there would be some interaction.  I tried a two clunk tank and found that it wasn't workable.  What works best (so far) on my DO-335 is two balloon tank set up.  However with pressure it may handle the longer tubing. 
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #31 on: August 29, 2013, 09:43:59 PM »
I am guessing that there would be some interaction.  I tried a two clunk tank and found that it wasn't workable.  What works best (so far) on my DO-335 is two balloon tank set up.  However with pressure it may handle the longer tubing. 
Right, with pressure the difference in line length can be compensated for with the needle valves, since there's always much more than enough pressure feeding the engine. The rear line can be longer with no ill effect, so the bladder can still straddle the C/G. In fact one bladder would assure that they both run out of fuel at the same time. Two bladders would only be a pain in the ass.

Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Jim Roselle

  • Guest
  • Trade Count: (0)
Re: Cox 1/2A engine question
« Reply #32 on: August 29, 2013, 10:24:00 PM »
Would running 2 engines off the same bladder cause a royal mess?
Phil
I've spent time pondering this myself. The problem I see is in the startup. With both engines running the pressure from the bladder is divided in two, and the needle  valves adjusted to run at that pressure. When the first motor is started and the fuel line is unclamped it is receiving fuel at twice the pressure it would when fuel flows freely to both motors. As long as the first motor can run ultra rich until the second motor is fired and the line unclamped it should be fine. I'm curious for someone to try it.

Jim

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #33 on: August 29, 2013, 10:54:03 PM »
Right, with pressure the difference in line length can be compensated for with the needle valves, since there's always much more than enough pressure feeding the engine. The rear line can be longer with no ill effect, so the bladder can still straddle the C/G. In fact one bladder would assure that they both run out of fuel at the same time. Two bladders would only be a pain in the ass.

Rusty

For my DO335 I want the front engine to quit first.  She lands nicely on one engine and then taxies a couple of laps on one. Judges love it.  You are thinking stunt - a hole different ball game.
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #34 on: August 30, 2013, 06:43:48 AM »
You're right, Jim, Big DUH! for me.
Rusty the doofus
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #35 on: August 30, 2013, 06:50:50 AM »
I have an idea, but this phone typing is driving me nuts. I'll get back to it later.
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Jim Roselle

  • Guest
  • Trade Count: (0)
Re: Cox 1/2A engine question
« Reply #36 on: August 30, 2013, 08:20:38 AM »
You're right, Jim, Big DUH! for me.
Rusty the doofus
You were right about two bladders being a pain in the ass! Just for the record; launching a twin from a wing stooge is another very bad idea ;D

Offline Larry Renger

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3842
Re: Cox 1/2A engine question
« Reply #37 on: August 30, 2013, 08:31:37 AM »
I've spent time pondering this myself. The problem I see is in the startup. With both engines running the pressure from the bladder is divided in two, and the needle  valves adjusted to run at that pressure. When the first motor is started and the fuel line is unclamped it is receiving fuel at twice the pressure it would when fuel flows freely to both motors. As long as the first motor can run ultra rich until the second motor is fired and the line unclamped it should be fine. I'm curious for someone to try it.

Jim

Unless the fuel flow rate is huge, there is NO pressure change when either or both engines run. The rubber tube puts out X amount of pressure and that is that.
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 Paul Smith

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 5156
Re: Cox 1/2A engine question
« Reply #38 on: August 30, 2013, 08:54:06 AM »
There are three main types of bladder tank:

Pen bladder - moderate pressure.
Pacifier -  somewhat more pressure.
Surgical tubing bladder - way too much pressure.

Crankcase pressure will also do the job.  If you can't find a pressure fitting you can glue a tube into the backplate.  As the phot shows, I did that, the plugged it off.  I did not need the extra power and the hassle that goe with it.

All the systems will result in the same gain in RPM & HP, but more pressure will make the system trickier to needle.

For scale I recommend DOWNSIZING the venturi to get more suction.  This trade a small amount of power for a HUGE gain in reliability.

Put pins (coated with grease of oil) in the spray hole.  Fill the venturi with JB Weld or another similar epoxy product.
When the glue dries pull the pins and redrill the venturi to a small size.

This works perfect on my F-86.  In fact, the plane came in nose heavy and I was able to move the tank farther aft.
« Last Edit: August 30, 2013, 07:54:33 PM by Paul Smith »
Paul Smith

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #39 on: August 30, 2013, 12:54:44 PM »
And the Norvel(NV) Big mig .061 is considered 1/2A these days. It's an absolutely awesome screamer and runs great on suction. Do NOT follow their break-in instructions. If you get one, come back here and ask about the first runs before you crank it. Their instructions are designed to reduce phone calls and e-mails from people who can't get their new engines to crank. And what they'll have you do to loosen it up before your first crank will damage your compression for life.

Rusty

EDIT: And order a starter spring with it too.

Rusty

I just ordered a NV AMD 061CL.  Tell me about the  first runs before I crank it
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #40 on: August 30, 2013, 01:36:00 PM »
Rusty

I just ordered a NV AMD 061CL.  Tell me about the  first runs before I crank it
Cool, you went for the hot rod.
I'll write it up before I post it. I want to take care and get it worded right, since others might follow these instructions too.

Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #41 on: August 30, 2013, 03:01:39 PM »
Cool, you went for the hot rod.
I'll write it up before I post it. I want to take care and get it worded right, since others might follow these instructions too.

Rusty

Cool it will take a day or two for it to arrive.  Prop recommendation would be cool also.
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #42 on: August 30, 2013, 09:45:56 PM »
The following is what I have learned about Norvel engines from people who have flown them for decades and whom I consider to be top notch engine tuners, who strongly keep longevity in mind. I have had great success following these procedures, though they do vary from NV Engines publications. I wonít repeat their methods here, but I do believe they are written for people who are not necessarily familiar with performance engines and find the startup to be extremely frustrating. Their method will get it going more easily, but, I believe, at the expense of premature wear. Read their information and consider it before you follow my advice. Iím an amateur modeler and cannot back up my methods with any sort of research. Please proceed after your own consideration of all options.

Read all of the tabs on the following page at NVEngines.com
http://www.nvengines.com/index.php?option=com_content&view=category&layout=blog&id=45&Itemid=18

Now, here is my method:
Once it's mounted in the test stand, leave the muffler off if you have one. These engines have a tight pinch at TDC between the piston and cylinder wall that makes it difficult to start the first few times. Try to resist flipping it over cold before you run it, as this unnecessarily wears the tight fitting P/C.

Since your AME is meant to run on pressure, if you start it up on suction only, mount your fuel tank with the feed line as short as possible and the internal pickup opening of the tank at least as high as the spraybar of the venturi. You can go higher, but beware of flooding, and you might want to clamp the line when not actually cranking to prevent gravity feeding the engine and flooding it. They are not friendly when flooded and can even bend a connecting rod if you try too vigorously. Do not use an electric starter, for this reason. A spring starter can be a big help. Anywhere from 15% to 25% nitromethane will make it happy. I currently use Sig Champion 25, and an extra dollop of castor in the jug is fine if you have some. Never use less than half castor in a castor/synthetic blend, and no less than 20% total oil. If you have any castor-only fuel, I would recommend that, but donít sweat it if you donít have any. Thatís only my own personal opinion. Make sure the fuel line is full of fuel and ready to go, clamp it off  if necessary, but donít connect it to the engine yet. Have the glow driver turned on and ready as well.

To make it easier to flip start, especially with no spring starter, it helps to reduce the compression by adding a couple of extra head gaskets. If you have any Cox copper gaskets, they will fit too.  In fact I got frustrated flipping my first Norvel and put a low compression Cox Babe Bee head on it and finally got it started, and ran it that way for one run. Since then, I know a better way, and if you follow the following instructions, the Norvel head will do fine.

The combustion heat causes metals of the piston and cylinder to expand from their cold state to form a perfect fit and let the piston move freely without the hard pinch. So to help that process along, heat the cylinder good and hot with a heat gun. This naturally relieves the pinch, making it easier to spin. Once hot, immediately connect the fuel line. Prime the venturi and give it a few brisk flips, then put a couple of drops in the exhaust. Connect the glow driver and give it a rip. Sometimes back flipping is easier, especially if youíre right handed. Either direction will fire it off. If you see it running backwards itís just burning off a flood. It might straighten out and kick off. If itís flooded badly, clamp the line and flip till you burn off the flood.

Once itís running, find the needle setting for a wet 2 cycle, then turn it on up to full speed. This engine needs heat and speed. The P/C needs immediate heat to fit up properly. Once it warms up, back it down and go back and forth between a brief wet 2 cycle and peak full speed for an ounce or so. Do NOT run it sloppy rich as this will not maintain the necessary heat to keep the pinch loose and will cause excessive wear. After an ounce, clamp it off and let it cool. Do this for several ounces, going back and forth from a brief wet 2 cycle for cooling, to a screaming peak, stopping and cooling completely after each ounce. When it will hold peak indefinitely without heating up and slowing it's ready to go. You can now go back to normal compression if you previously reduced it.

It may not be fast at first, but it will keep breaking in as you fly it until it's really an all out screamer. I also think the 6x3 prop recommended by NV Engines is too much for it(possibly another dumbed down idea for easy cranking). This engine is meant to run higher RPMs than a 6x3 will allow. I would use at most a 5.5x3 for the first run, or even less. If you use APC props, a 6x2 will get it up there, but most others need to be shorter. Remember, the AME needs high RPMs to draw fuel, and will need pressure for flying. A bladder is my preferred fuel supply.

I have 3 Big Migs, and one AME. Once they start really breaking in it will turn a 5x3 prop about 23-24k RPM. I have three Big Migs that are now fully run-in after flying and they will all turn a Master Airscrew GF 5x3 at around 25-26k. But it takes a lot of running to get there. Like I said, as you fly, it will continue to break in. My oldest Big Mig will spin an APC 5x2.5 at 28.8kRPMs. Your AME should blow its doors off. In fact, on my one little AME powered combat plane, I use an APC under 5" long with a 3" pitch

One thing I like to change right away is the prop screw. The supplied screw does not reach very far into the crankshaft. I like screws that go in deep, so I use replacement Black oxide hex head screws that are 3mm x 25mm. I also prefer the ones with an un-threaded shoulder as it fits the Norvel spinner better.

Have fun and come back and let us know how it goes.
Rusty
« Last Edit: September 12, 2017, 02:44:02 AM by RknRusty »
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #43 on: August 31, 2013, 11:12:52 AM »
Rusty,

It all makes sense what you recommend.  The use of a heat gun is really a neat idea. If I read you correct ten 1 oz runs on the bench and she should be good to go. I want her really broken in before  I place her on my DO-335.
 
By the way it looks like mine will not have a muffler.  Shouldn't be a problem to run without a muffler.

Thanks for sharing!

 #^   #^   #^
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #44 on: August 31, 2013, 11:52:30 AM »
John, 10oz is more than enough. Once it'll hold a peak needle, you can bolt her on and fly. It'll keep breaking in like that for a while.
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline George

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1468
  • Love people, Use things.
Re: Cox 1/2A engine question
« Reply #45 on: August 31, 2013, 12:47:43 PM »
Another side benefit of heating the cylinder before running is that it will put less stress on the connecting rod lower end which breaks-in during the first couple of minutes. Even if you do not pre-heat the cylinder, get it up to temp ASAP...same reason.

This applies to ABC, ABN, etc. cylinders as well as Revlite.     

George
George Bain
AMA 23454

Offline Larry Renger

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3842
Re: Cox 1/2A engine question
« Reply #46 on: August 31, 2013, 02:47:40 PM »
I agree with the above break in procedure. Only comment is thst I think the thread sixe is M 3 x .5 .
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 John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #47 on: September 04, 2013, 06:46:36 PM »
Well the NV AMD 061CL arrived today. Just started to do breakin.  However I can already tell it will be strong!

 #^   #^   #^
John Rist
AMA 56277

Offline RknRusty

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2803
    • My Tube channel
Re: Cox 1/2A engine question
« Reply #48 on: September 05, 2013, 06:59:43 AM »
Well the NV AMD 061CL arrived today. Just started to do breakin.  However I can already tell it will be strong!

 #^   #^   #^
Sounds like fun. The newer Big Migs are famous for wobbly leaky venturis because the o-rings aren't up to snuff. I don't know if the AMDs are like this, but if the needle seems erratic, check that. I finally got tired of fooling with it and JB Welded one of my BM venturis in place.
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline John Rist

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2505
Re: Cox 1/2A engine question
« Reply #49 on: September 05, 2013, 08:04:17 AM »
Sounds like fun. The newer Big Migs are famous for wobbly leaky venturis because the o-rings aren't up to snuff. I don't know if the AMDs are like this, but if the needle seems erratic, check that. I finally got tired of fooling with it and JB Welded one of my BM venturis in place.
Rusty
Rusty,

I am looking at the data sheet for the .049 / .061 AMD Sport Engine and it does not list a venture as a separate item.  It looks like on the CL version that the venture is now part of the case.

 ???
John Rist
AMA 56277


Advertise Here
Tags: