9 Cylinder Radial Build using Cox Sure Start 049's - Page 4 - RC Groups
Thread Tools
Oct 02, 2011, 12:52 PM
Double Naught Spy
iamplanecrazy2's Avatar
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
Sign up now
to remove ads between posts
Oct 06, 2011, 08:44 AM
Double Naught Spy
iamplanecrazy2's Avatar
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.
Oct 07, 2011, 10:58 PM
Former B52H Crew Chief
aerofly0610's Avatar
anxious to see video of it running, please make it HD
Oct 10, 2011, 04:18 AM
Registered User
Madguns's Avatar
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
Oct 10, 2011, 04:20 AM
Registered User
Madguns's Avatar
Are you planning to index/time each engine so that only one cylinder fires at a time?
Oct 10, 2011, 09:56 AM
Double Naught Spy
iamplanecrazy2's Avatar
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.
Oct 11, 2011, 10:54 PM
Registered User
Quote:
Originally Posted by iamplanecrazy2
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.
Oct 11, 2011, 11:25 PM
Double Naught Spy
iamplanecrazy2's Avatar
Quote:
Originally Posted by 706jim
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 )
Last edited by iamplanecrazy2; Oct 11, 2011 at 11:31 PM.
Oct 12, 2011, 09:06 AM
AMA 8711, FCC K4WZA
DPlumpe's Avatar
Quote:
Originally Posted by iamplanecrazy2
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
Oct 15, 2011, 02:43 AM
Registered User
Madguns's Avatar

How about...


4 rows of 7?
Oct 16, 2011, 03:50 AM
TigreJohn
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.
Oct 16, 2011, 04:28 AM
Registered User
surfer_kris's Avatar
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...
Oct 16, 2011, 10:01 AM
Registered User
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
Oct 16, 2011, 11:13 AM
I don't want to "Switch Now"
pmackenzie's Avatar
Quote:
Originally Posted by John_R_C

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
Oct 16, 2011, 11:34 AM
Registered User
Toysrme's Avatar
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


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold 2 Cox 049 Sure Start Engines fchriss Aircraft - Fuel - Engines and Accessories (FS/W) 2 Dec 09, 2008 12:36 PM
For Sale 2 Cox .049 sure start's snomobila Aircraft - Fuel - Engines and Accessories (FS/W) 3 Dec 07, 2008 10:36 PM
Question Which fuel for Cox .049 Sure Start? ndb8fxe 1/2A Planes 6 Aug 30, 2008 11:52 PM
Question Cox Sure Start .049 EricClark 1/2A Planes 25 May 15, 2008 01:16 AM
Question Need info about Cox Sure Start .049 engine please JLW5178 Beginner Training Area (Fuel) 16 May 03, 2008 05:20 PM