Information for Two Cycle Engines used in pattern.

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OS-140 RX

ST 2300 (1.4cu)

Webra 145

OS-160

Mintor 3M 170

3M 140

MVVS 160 Benz

1

OS-140 RX #1

Ron Lockhart

Galloway New Jersey
Tank Size Specify Oz or CC    16oz Type Plug   OS-F  Elevation of test 20 feet
Header OS Pipe Old Hatori .60 size "bent" pipe Temp of Exhaust  
Tunnel Length   38" Temperature Day of Test 
70 to 90 F		 Fuel 1 15%, S&W
Prop Size #1 17x10N  APC RPM for #1 RPM 8000  
Prop Size #2  RPM for #2 Fuel if not Fuel 1
Prop Size #3 RPM for #3 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) N/A OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
26 in along header path
Number of Flights Before Bearing Change If Known  N/A Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  1.3 min/oz in sequence
Comments:
OS-F plug.  Idle set very lean.  Never touched pump adjustment.  Had poor longevity with ceramic bearings. I use Mobile One full synthetic auto oil as after run.

 

 

OS-140 RX #2

Ed Hartley

Knoxville Tennessee
Tank Size Specify Oz or CC    16oz Type Plug   OS-F  Elevation of test  1024 ASL
Header MACS 1-1/4" Rise Pipe O.S. T-6010 Temp of Exhaust   130C - 266F
Tunnel Length   38" Temperature Day of Test  95F Fuel 1 Mach 7 - 25%
Prop Size #1 16x14 APC RPM for #1 RPM 7900  
Prop Size #2 15-1/2 12 APC Four Blade RPM for #2 7780
(Idles at 1280 all day long)		 Fuel if not Fuel 1
Prop Size #3 RPM for #3 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) 229mm OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
From the center of the plug to first baffle is 19-5/8"
Number of Flights Before Bearing Change If Known  None Yet Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  Approximately 9 0z for Masters Pattern
Sound measurements as measured by distance and Db 89Db at twenty-five feet
Comments:
I started out using a sixty size pipe and the mid range was terrible as the OS Site stated it would be. See http://www.osengines.com/faq/product-faq.html#q266  I purchased the O.S. T-6010 Tuned Silencer and this fixed the problem. The throttle curve is very smooth. The engine is used in a Zimpro Viper shown on the opening page of this web site.

I set the idle to 1750 rpm and it runs just great!
On the four blade prop I set the idle at 1380.

I used the OS-5 plug that came with the engine and later found the OS-F8 plug last much longer and works just as well.

I started with a 16x12 and that just wasn't enough prop. I then changed to the 16x14 APC and this works well.
Sid Austin of Pyramid Hobbies put me on to this setup. Using a four blade APC 15-1/2x12 prop, I find much the same results as Steve Maxwell talks about in his OS-140 RX #7 on this page. I am absolutely amazed at hot slow it comes down hill with this prop. Likewise the vertical is slower but unlimited. You can take off and accelerate in the verticle!

It is interesting to note you must apply some power to get your normal glide ratio on landing. It has a tremendous breaking action and when you touch down it stops very quickly. Throttle management is a must, particularly in level flight.

The 16oz fuel tank is located on the center of gravity.

When I am through for the day, I disconnect the fuel line and run the engine at a fast idle until it quits. No after run oil.

I can't tell you how long the bearings will last. As soon as it eats the original ones, I will post it here.
(218 Flights on the original bearings, ring etc. and still going strong!)

This engine makes unbelievable power.

 

 

OS-140 RX #3

Brian Hebert

Denham Springs Louisiana
Tank Size Specify Oz or CC   450 cc Type Plug   OS-F  Elevation of test  100 ASL
Header Hatori standard with O-ring header flange Pipe
large volume carbon ES pipe		 Temp of Exhaust   120C
Tunnel Length   35" Temperature Day of Test  90F Fuel 1 20% pattern blend Cool power
Prop Size #1 modified 17-3/4n APC RPM for #1 RPM 8000  
Prop Size #2   modified 17-5/8n APC RPM for #2 8200 Fuel if not Fuel 1
Prop Size #3 modified APC 17.5-12n RPM for #3 8300 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) N/A OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
 24.5 inches
Number of Flights Before Bearing Change If Known  Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  12-13 min or 8 flights a gallon
Comments:
I have run the set up at 23.5 to the first baffle when using the 17.12n standard APC props running the EFI version of the O.S.1.4 running the Syn fuel verses pure caster made no difference on bearing life or temp just clean up. although the injector would get stuck with the caster fuel from time to time  I never after run the motor and always store it nose High

 

 

OS-140 RX #4

Mike Hester

Woodstock Georgia
Tank Size Specify Oz or CC  580cc Type Plug   OS F  Elevation of test  500 ft or so
Header OS Stock Pipe ES 2C140M80 Carbon Temp of Exhaust  
Tunnel Length   38 Temperature Day of Test  93 Fuel 1 10% Omega
Prop Size #1 APC 16x13 RPM for #1 8000  
Prop Size #2     Bolly 16x13W RPM for #2 8100 Fuel if not Fuel 1
Prop Size #3 RPM for #3 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) 10 inches OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
 
Number of Flights Before Bearing Change If Known  around 300 consistently, ring a bigger issue Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  15+
Comments:
My favorite engine. When set up properly, it's so bullet proof even I can't mess it up.

It seems a bigger issue than fuel pertaining to bearing life is cooling air to the crank case. That being said, I have only run a castor/synthetic blend and have so far not had a bearing failure.

Full break in takes a few gallons, mostly in the air and on the rich side. My experience is that it has been pointless to set the idle apart from factory settings before a few gallons of fuel. Then after break in, set the needles and don't touch until the ring fails, so far that's been about 300 flights on every one.

Usually around 300 flights the engine sags in verticals and the transition becomes rough. So far in 3 engines this has meant a new ring and a bearing change for good measure (although none of the bearings were actually bad). Pretty cheap and easy maintenance for 300 runs in my opinion.

Performs well on a variety of props. After running the 17x12, 17x10, Bolly 17.5x12, 16x14, 16x12, and 16x13, the 16x13W Bolly gives the best performance, but is also the loudest. The 16x13 APC is very quiet and has a very nice speed/power envelope for this particular airframe (Typhoon 2000).

 

 

OS-140 RX #5

Verne Koester

Livonia Michigan
Tank Size Specify Oz or CC  20 oz. Type Plug   OS-F  Elevation of test  580
Header Mac's 4742 Pipe E.S. Composites 2C140L90 Temp of Exhaust   Cool Power 15%
Tunnel Length   Test Stand Temperature Day of Test  85 Fuel 1
Prop Size #1 APC 17 X 12 RPM for #1 8300-8500  
Prop Size #2     RPM for #2 Fuel if not Fuel 1
Prop Size #3 RPM for #3 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
 22.5
Number of Flights Before Bearing Change If Known  ? Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  
Comments:
My figures are from bench tests. The engine is slated to go into a Smaragd if I ever get it. The rpm's I got were consistent with the numbers Jerry Budd posted on the NSRCA Discussion List awhile back. At this point, it appears to be a very good setup but the final tale can only be told in the air. This setup is quite simple. Buy it and bolt it on without cutting anything. The header and pipe are both full length with about a 3/8" gap between the two inside the silicone coupler.

 

 

OS-140 RX #6

Kurt Bozarth

Aurora Colorado
Tank Size Specify Oz or CC  16 oz. Type Plug   OS-F  Elevation of test  6300' MSL
Header Macs 4742 Pipe Bolly 480R  Muffler Temp of Exhaust  
Tunnel Length  Stock header/muffler uncut Temperature Day of Test  90 Fuel 1 10% nitro /  Cool Power
Prop Size #1 APC 16x14 RPM for #1 7800  
Prop Size #2     RPM for #2 Fuel if not Fuel 1
Prop Size #3 RPM for #3 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) N/A OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
 
Number of Flights Before Bearing Change If Known  Original bearings / 75 flights Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  12 minutes
Comments:
Both of my engines were slightly rich on the low side. Low speed needle has been rotated right to approximately the 2 o'clock position.  The Bolly muffler is much smoother sounding than the CD metal muffler originally used. Both of my engines have approx. 75-100 flights with no indication of bearing problems.  Both of my engines are hard-mounted.  I have never adjusted the pump settings.  Both start easily and have never flamed out in the air.  I run them conservatively rich.

 

 

OS-140 RX #7

Steve Maxwell

Greenwood Indiana
Tank Size Specify Oz or CC  500cc Tetra Type Plug   OS F  Elevation of test  500 ft
Header OS bent to fit Focus Pipe Bolly MF590r Temp of Exhaust  
Tunnel Length   Temperature Day of Test 85 Fuel 1 Magnum #1, 2-cycle
Prop Size #1 15.5 X12 APC 4 blade RPM for #1 8150  
Prop Size #2  17 X12 APC   2 blade RPM for #2 7760 Fuel if not Fuel 1
Prop Size #3 17X13 APC 2 blade RPM for #3 7725 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) Full length header and pipe fit up tight to each other OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
 
Number of Flights Before Bearing Change If Known  Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  15 minutes w/ 1/4 tank left
Comments:
All test was on a Focus at 10lb 10.5 oz, the 4-blade has a very slow presentation which can be a product of Throttle management as you can see from the fuel consumption that I fly a lot at low throttle (probably to slow at times). I'm using an OS 7D needle valve only because I had one and the engine (bought used) only came with the blunt needle and it fit, the 7D is about half as long as the long as the long taper, and works great. The 4-blade has good vertical and is a little more work to fly than the 2 blade because of the thrust, the 2-blade seems to pull better lines in the verticals but fly's much faster all around, besides the up line thrust issue the 2-blade seems to do better on the top of square corners, on the other hand the 4 blade  doing a reverse Cuban you can take a nap though, can make as big as you want and have taken up the whole box to do at 225 meters so the power is there, the big issue is throttle management. I'm getting close to a hundred flights and no sign of bearing ware. I love this setup very simple easy to use and hand starts (use a chicken stick please) Even at that I am going to use the Webra on my next project.

Mount Peidmont Dave Brown soft mount, I don't use after run or even run fuel out, leave carb in the cut off position and flying most every day which would make a difference. One of the really great things about the Peidmont Dave Brown soft mount is easy thrust adjustment just tighten up bolts as needed to change. No sign of wear, I did use Locktite on the bolt to insure that they didn't back out.

Have fun fly safe and practice, practice, practice.

 

 

OS-140 RX #8

Jeff Hughes

Columbus Indiana
Tank Size Specify Oz or CC   Type Plug   OS F  Elevation of test  700 ft
Header Mac Pipe Bollly 590 Temp of Exhaust  
Tunnel Length   Temperature Day of Test 85F Fuel 1 15% Cool Power
Prop Size #1 15.5 x12 4-blade RPM for #1 7850  
Prop Size #2   RPM for #2 Fuel if not Fuel 1
Prop Size #3 RPM for #3 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
 
Number of Flights Before Bearing Change If Known  Not Known Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  
Comments:
Like Steve, I've gotten used to the 4blades ability to slow the plane down. Makes for a very pretty presentation. I've also used a 16-13N and 17-10N both louder and less down line braking.

 

 

OS-140 RX #9

Rick Wallace

Toms  River New Jersey
Tank Size Specify Oz or CC  16oz Type Plug   OS F  Elevation of test  35 ft
Header Macs Pipe   Bolly 480 Muffler Temp of Exhaust  
Tunnel Length   Temperature Day of Test 75F Fuel 1 20% S&W
Prop Size #1 17x10N   2 blade APC RPM for #1 8400  
Prop Size #2  15.75x10 3 Blade APC RPM for #2 8000 Fuel if not Fuel 1
Prop Size #3 RPM for #3 Fuel if not Fuel 1
Distance From Exhaust Outlet to Start of Pipe (Straight Line) OR Distance From Exhaust  Outlet to First Baffle In Pipe (Straight Line)
 
Number of Flights Before Bearing Change If Known  Changed in June '02 -- 175+ (so far) on the new set set Typical Run Time in Minutes Per Tank of fuel. Fuel used means consumption As typically used flying the pattern  9 Minutes
Comments:
This engine and exhaust combo is a SWEETHEART. One of the easiest engines I've ever had for ease of set up and operation! Stable 1600-1650 rpm idle w/ either 3 or 4 blade props. VERY quiet in the air with 14.5 - 15.75" 3 or 4 blade props 15.75 x 10 3 blade is awesome - pulls great, constant speed -level or uphill,- and best downhill braking I've seen - better than any 4 blade prop I've tried.

At the end of the day I always run it dry and use Amsoil spray Metal Protectant

Not bad for a used engine bought at the WRAMS show swap shop!!

 

 

OS-140 RX #10