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Old Oct 02, 2011, 12:52 PM
Double Naught Spy
iamplanecrazy2's Avatar
USA, TX, Waxahachie
Joined Aug 2004
380 Posts
Thanks for the input boingk.
I do have some MiMh AA's that I think would be up to the task.

Here is a link to a page that shows Ralph Barnett's 5 cylinder radial being bench run.
If I ever get that far with this project I'll use the same glow driver set up.
It looks to me like there is a switch to the rear of the fuel tank on the ground side.

I had the good fortune to have visited with Ralph on several occasions. He was a
real character and a heck of a craftsman. He also built 2 and 3 cylinder engines based
on Cox 049's. His engines are a real inspiration to me.

http://modelenginenews.org/gallery/p8.html
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Old Oct 06, 2011, 08:44 AM
Double Naught Spy
iamplanecrazy2's Avatar
USA, TX, Waxahachie
Joined Aug 2004
380 Posts
All of the gears came in yesterday. They are lining up nicely and their arrival
confirms that the ST 60 front end is going to work out fine. I've been holding off
on doing anything to it until the gears came in. Didn't want to mess up a perfectly
good front housing until I was sure it would work. It will be Tuesday before I can
get started as we have company until then. I'll try to get a photo posted of the
engine with the gears on it.
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Old Oct 07, 2011, 10:58 PM
Former B52H Crew Chief
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Green Bay WI
Joined Feb 2009
781 Posts
anxious to see video of it running, please make it HD
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Old Oct 10, 2011, 04:18 AM
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United States, FL, Navarre
Joined May 2004
274 Posts
WOW!

Allot of people have thought and pondered this. Sounds real easy until it comes time to start cutting metal, drilling holes and finding the proper gears.

Really really cool. If you could come up with a kit minus the engines, I don't think you could keep up with demand.

-John
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Old Oct 10, 2011, 04:20 AM
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Madguns's Avatar
United States, FL, Navarre
Joined May 2004
274 Posts
Are you planning to index/time each engine so that only one cylinder fires at a time?
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Old Oct 10, 2011, 09:56 AM
Double Naught Spy
iamplanecrazy2's Avatar
USA, TX, Waxahachie
Joined Aug 2004
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aerofly, I'm very anxious to see it run too! Will be back to work on it in a couple more days.

Thanks John, if it actually runs I have thought about at least creating plans with photo
illustrated instructions. I would like to perform test runs with all cylinders firing at the
same time as well as one at a time. It will definitely create a better sound if firing one at a time.
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Old Oct 11, 2011, 10:54 PM
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Quote:
Originally Posted by iamplanecrazy2 View Post
I would like to perform test runs with all cylinders firing at the same time as well as one at a time. It will definitely create a better sound if firing one at a time.
I'd be interested to hear it with sequentially firing cylinders. Years ago, I ran my K & B sky fury 0.099 and figured I had a real powerhouse, turning a 7 x 4 at 19000rpm. It turns out the exhaust note was 19000, but crankshaft rpm was about 9500; not particularly powerful.
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Old Oct 11, 2011, 11:25 PM
Double Naught Spy
iamplanecrazy2's Avatar
USA, TX, Waxahachie
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Quote:
Originally Posted by 706jim View Post
I'd be interested to hear it with sequentially firing cylinders. Years ago, I ran my K & B sky fury 0.099 and figured I had a real powerhouse, turning a 7 x 4 at 19000rpm. It turns out the exhaust note was 19000, but crankshaft rpm was about 9500; not particularly powerful.
Me too!

Could the .099 be hopped up?

If this works an 18 cylinder version would be a fun follow up. Or why not 10 twins in a circle for
20 cylinders? Wish the Fury twins cost $6.99 each. (that they don't would be a good why not )
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Old Oct 12, 2011, 09:06 AM
AMA 8711, FCC K4WZA
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Salem, SC
Joined Mar 2003
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Quote:
Originally Posted by iamplanecrazy2 View Post
I would like to perform test runs with all cylinders firing at the same time as well as one at a time. It will definitely create a better sound if firing one at a time.
Suggest you try opposite-firing sequance (1,6,2,7,3,8,4,9,5...). Should have sequential-firing sound (or maybe even more interesting) with nearly the low vibration of simultaneous-firing.

-Dave
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Old Oct 15, 2011, 02:43 AM
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United States, FL, Navarre
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How about...

4 rows of 7?
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Old Oct 16, 2011, 03:50 AM
TigreJohn
United States, CA, Corona
Joined Aug 2008
1,005 Posts
Gentlemen, he is building this engine using Cox .049 motors. They are 2 cycle glow fuel engines which are "compression ignition". He has NO NON-MECHANICAL CONTROL over their firing sequence. They will be nine individuals each sequentially ignition firing 2.5 times per propeller revolution. He has the choice will be having the gearing choice. He can have all nine cylinders firing at the same time 2.5 times per prop rev. Or he could have the cylinders firing in true radial fashion sequentially 22.5 times per prop rev. His problem will be indexing the teeth of the gearing so that the cylinders fire in either sequence. I would love to hear the difference between the two.
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Old Oct 16, 2011, 04:28 AM
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surfer_kris's Avatar
Sweden
Joined Jan 2008
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Compression ignition doesn't change anything as I see it, it is always set by the gears, just a little fewer options with two-stroke compared to four-stroke engines...
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Old Oct 16, 2011, 10:01 AM
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Broomfield, CO 80023
Joined Dec 2002
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I'd be interested to hear it with sequentially firing cylinders. Years ago, I ran my K & B sky fury 0.099 and figured I had a real powerhouse, turning a 7 x 4 at 19000rpm. It turns out the exhaust note was 19000, but crankshaft rpm was about 9500; not particularly powerful. - 706

Sorry, but two strokes fire every revolution, so both the RPM and exhaust note would be at the same frequency. Four strokes fire every other revolution, so exhaust frequency is half engine RPM.

John C
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Old Oct 16, 2011, 11:13 AM
I don't want to "Switch Now"
pmackenzie's Avatar
Toronto (Don Mills), Canada
Joined Dec 2002
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Quote:
Originally Posted by John_R_C View Post

Sorry, but two strokes fire every revolution, so both the RPM and exhaust note would be at the same frequency. Four strokes fire every other revolution, so exhaust frequency is half engine RPM.

John C
Unless that 2 stroke is an inline alternate firing twin

http://www.worthpoint.com/worthopedi...9-kb-134165126

Pat MacKenzie
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Old Oct 16, 2011, 11:34 AM
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Birmingham, Alabama
Joined Jun 2002
2,970 Posts
if it were me, id want it to be opposite sequential firing just to be able to tell if & which cox engine is misfiring lulz!

project is baller
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