OS 120 AX Prop Size ?
07-18-2006, 11:18 PM
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RE: OS 120 AX Prop Size ?
I am glad to see this post... hopefully it will help me also. I am running a 120AX in a Showtime and am about ready to drop kick this engine! Very dissapointed so far and almost wish for my old reliable Supertigre G-90!
After a conservative break in I am running a 16-6 APC and it tachs at 93-9400 after warm up but as soon as it lifts off it SIGNIFICANTLY drops. The aircraft acts like it is severly underpowered... it struggles to sustain vertical and BARELY hovers!
I tried a 16-4 APC trying to lighten the load that revved 10200, way above its intended RPM range. The engine did maintain a consistent RPM but the aircraft struggled to flatten out and fly obviously due to the low pitch and not being able to harness any power.
In an effort to load the engine more, tonight I bolted a 16-8 APC onto and gave it a shot. It tached at 8900 RPM before take off but REALLY dropped off after it went airborne. From half throttle to full throttle the RPM did not change and the aircraft could not sustain vertical climb. It was obvious that it was overpropped.
I switched glow plugs from the O.S. 8 to an Enya No. 6 and gained about 200 RPM with stronger acceleration.
Here is my set up...HHHEEELLLPPP!!!
15% Cool Power with 1/2 gallon burned
16-6 APC @9300 RPM
Enya No.6
Stock Exhaust with no extension.
Engine is mounted slightly below flat.
Thanks,
Propwrench
After a conservative break in I am running a 16-6 APC and it tachs at 93-9400 after warm up but as soon as it lifts off it SIGNIFICANTLY drops. The aircraft acts like it is severly underpowered... it struggles to sustain vertical and BARELY hovers!
I tried a 16-4 APC trying to lighten the load that revved 10200, way above its intended RPM range. The engine did maintain a consistent RPM but the aircraft struggled to flatten out and fly obviously due to the low pitch and not being able to harness any power.
In an effort to load the engine more, tonight I bolted a 16-8 APC onto and gave it a shot. It tached at 8900 RPM before take off but REALLY dropped off after it went airborne. From half throttle to full throttle the RPM did not change and the aircraft could not sustain vertical climb. It was obvious that it was overpropped.
I switched glow plugs from the O.S. 8 to an Enya No. 6 and gained about 200 RPM with stronger acceleration.
Here is my set up...HHHEEELLLPPP!!!
15% Cool Power with 1/2 gallon burned
16-6 APC @9300 RPM
Enya No.6
Stock Exhaust with no extension.
Engine is mounted slightly below flat.
Thanks,
Propwrench
07-19-2006, 10:51 AM
#5
RE: OS 120 AX Prop Size ?
I'm running an APC 17X6 on my 120AX thats mounted on the business end of Seagulls Laser 200
07-19-2006, 10:59 AM
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RE: OS 120 AX Prop Size ?
ORIGINAL: PropWrench
I am glad to see this post... hopefully it will help me also. I am running a 120AX in a Showtime and am about ready to drop kick this engine! Very dissapointed so far and almost wish for my old reliable Supertigre G-90!
After a conservative break in I am running a 16-6 APC and it tachs at 93-9400 after warm up but as soon as it lifts off it SIGNIFICANTLY drops. The aircraft acts like it is severly underpowered... it struggles to sustain vertical and BARELY hovers!
I tried a 16-4 APC trying to lighten the load that revved 10200, way above its intended RPM range. The engine did maintain a consistent RPM but the aircraft struggled to flatten out and fly obviously due to the low pitch and not being able to harness any power.
In an effort to load the engine more, tonight I bolted a 16-8 APC onto and gave it a shot. It tached at 8900 RPM before take off but REALLY dropped off after it went airborne. From half throttle to full throttle the RPM did not change and the aircraft could not sustain vertical climb. It was obvious that it was overpropped.
I switched glow plugs from the O.S. 8 to an Enya No. 6 and gained about 200 RPM with stronger acceleration.
Here is my set up...HHHEEELLLPPP!!!
15% Cool Power with 1/2 gallon burned
16-6 APC @9300 RPM
Enya No.6
Stock Exhaust with no extension.
Engine is mounted slightly below flat.
Thanks,
Propwrench
I am glad to see this post... hopefully it will help me also. I am running a 120AX in a Showtime and am about ready to drop kick this engine! Very dissapointed so far and almost wish for my old reliable Supertigre G-90!
After a conservative break in I am running a 16-6 APC and it tachs at 93-9400 after warm up but as soon as it lifts off it SIGNIFICANTLY drops. The aircraft acts like it is severly underpowered... it struggles to sustain vertical and BARELY hovers!
I tried a 16-4 APC trying to lighten the load that revved 10200, way above its intended RPM range. The engine did maintain a consistent RPM but the aircraft struggled to flatten out and fly obviously due to the low pitch and not being able to harness any power.
In an effort to load the engine more, tonight I bolted a 16-8 APC onto and gave it a shot. It tached at 8900 RPM before take off but REALLY dropped off after it went airborne. From half throttle to full throttle the RPM did not change and the aircraft could not sustain vertical climb. It was obvious that it was overpropped.
I switched glow plugs from the O.S. 8 to an Enya No. 6 and gained about 200 RPM with stronger acceleration.
Here is my set up...HHHEEELLLPPP!!!
15% Cool Power with 1/2 gallon burned
16-6 APC @9300 RPM
Enya No.6
Stock Exhaust with no extension.
Engine is mounted slightly below flat.
Thanks,
Propwrench
My engine is running inverted, I am using the stock muffler with the straight adapter extension. I'm not sure how you could install the motor with no extension, mine just clears the cowl. I use an O.S. #8 plug, Coolpower 10%.
As for power, I can hover at 1/3 to 1/2 throttle. Pull out of hover is fine. I would expect good performance as the plane weights a bit over 9 lbs and the thrust must be in the 13 to 15 lbs range.
Malcolm
07-20-2006, 12:07 AM
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RE: OS 120 AX Prop Size ?
Malcolm,
It really bothered me thinking about cutting the cowling so I boxed in an exhaust relief on the lower side of the bulkhead. The engine fits nicely at a 8 O-clock position if you were standing in front the aircraft. I added some venting so air could enter in front of the cylinder and really opened up the bottom for a good exit.
Propwrench.
It really bothered me thinking about cutting the cowling so I boxed in an exhaust relief on the lower side of the bulkhead. The engine fits nicely at a 8 O-clock position if you were standing in front the aircraft. I added some venting so air could enter in front of the cylinder and really opened up the bottom for a good exit.
Propwrench.
07-20-2006, 05:18 AM
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RE: OS 120 AX Prop Size ?
G'day
I too have this engine and what can i say but this engine is so sweeet!! Fellas out there with prop issues I have found that an APC 15x10 is the best prop for this engine or even a bolly prop 15X11 is even better. I am running it on a yt-international Adrenaline 120 and the combination is outstanding. My club has a ceiling of 1000 ft and my engine halls this plane up to that height just after take-off in about 10-20 seconds. no joke!!!
I too have this engine and what can i say but this engine is so sweeet!! Fellas out there with prop issues I have found that an APC 15x10 is the best prop for this engine or even a bolly prop 15X11 is even better. I am running it on a yt-international Adrenaline 120 and the combination is outstanding. My club has a ceiling of 1000 ft and my engine halls this plane up to that height just after take-off in about 10-20 seconds. no joke!!!
08-10-2006, 09:58 PM
#9
RE: OS 120 AX Prop Size ?
Just a update, I broke in the 120 ax in on the ground with some Wildcat 15% with some castor added. After 7 tanks fulls with a 16x6 apc I'm running a very rich 9400 rpm with the baffle removed. I did very breifly lean it out to 9900 rpm. i think i might have to go with a 17x6 since I'm running it in a Funtana X100.
08-11-2006, 04:11 AM
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RE: OS 120 AX Prop Size ?
ORIGINAL: PropWrench
I am glad to see this post... hopefully it will help me also. I am running a 120AX in a Showtime and am about ready to drop kick this engine! Very dissapointed so far and almost wish for my old reliable Supertigre G-90!
After a conservative break in I am running a 16-6 APC and it tachs at 93-9400 after warm up but as soon as it lifts off it SIGNIFICANTLY drops. The aircraft acts like it is severly underpowered... it struggles to sustain vertical and BARELY hovers!
I tried a 16-4 APC trying to lighten the load that revved 10200, way above its intended RPM range. The engine did maintain a consistent RPM but the aircraft struggled to flatten out and fly obviously due to the low pitch and not being able to harness any power.
In an effort to load the engine more, tonight I bolted a 16-8 APC onto and gave it a shot. It tached at 8900 RPM before take off but REALLY dropped off after it went airborne. From half throttle to full throttle the RPM did not change and the aircraft could not sustain vertical climb. It was obvious that it was overpropped.
I switched glow plugs from the O.S. 8 to an Enya No. 6 and gained about 200 RPM with stronger acceleration.
Here is my set up...HHHEEELLLPPP!!!
15% Cool Power with 1/2 gallon burned
16-6 APC @9300 RPM
Enya No.6
Stock Exhaust with no extension.
Engine is mounted slightly below flat.
Thanks,
Propwrench
I am glad to see this post... hopefully it will help me also. I am running a 120AX in a Showtime and am about ready to drop kick this engine! Very dissapointed so far and almost wish for my old reliable Supertigre G-90!
After a conservative break in I am running a 16-6 APC and it tachs at 93-9400 after warm up but as soon as it lifts off it SIGNIFICANTLY drops. The aircraft acts like it is severly underpowered... it struggles to sustain vertical and BARELY hovers!
I tried a 16-4 APC trying to lighten the load that revved 10200, way above its intended RPM range. The engine did maintain a consistent RPM but the aircraft struggled to flatten out and fly obviously due to the low pitch and not being able to harness any power.
In an effort to load the engine more, tonight I bolted a 16-8 APC onto and gave it a shot. It tached at 8900 RPM before take off but REALLY dropped off after it went airborne. From half throttle to full throttle the RPM did not change and the aircraft could not sustain vertical climb. It was obvious that it was overpropped.
I switched glow plugs from the O.S. 8 to an Enya No. 6 and gained about 200 RPM with stronger acceleration.
Here is my set up...HHHEEELLLPPP!!!
15% Cool Power with 1/2 gallon burned
16-6 APC @9300 RPM
Enya No.6
Stock Exhaust with no extension.
Engine is mounted slightly below flat.
Thanks,
Propwrench
I have this engine on a sport speed plane and must say it unloads very well in the air, almost like the engines running on a tuned pipe. The muffler that comes with the 120AX is somehow tuned so maybe because you are running without the extensions the tuning is changed and is not working as it should at 9000rpm but you maybe instead need 10-11000rpm to make it work at its best?. I am not 100% sure about this idea but what you described made me think that way bacause my engine is acting the other way and unloads very good in vertical climbs turning a APC 14x12@9000rpm. I would also add atleast 6oz/gallon pure castor oil in the fuel for better cooling and protection against lean runs. Let us know your findings.
08-11-2006, 08:14 AM
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RE: OS 120 AX Prop Size ?
ORIGINAL: PropWrench
I am glad to see this post... hopefully it will help me also. I am running a 120AX in a Showtime and am about ready to drop kick this engine! Very dissapointed so far and almost wish for my old reliable Supertigre G-90!
After a conservative break in I am running a 16-6 APC and it tachs at 93-9400 after warm up but as soon as it lifts off it SIGNIFICANTLY drops. The aircraft acts like it is severly underpowered... it struggles to sustain vertical and BARELY hovers!
I tried a 16-4 APC trying to lighten the load that revved 10200, way above its intended RPM range. The engine did maintain a consistent RPM but the aircraft struggled to flatten out and fly obviously due to the low pitch and not being able to harness any power.
In an effort to load the engine more, tonight I bolted a 16-8 APC onto and gave it a shot. It tached at 8900 RPM before take off but REALLY dropped off after it went airborne. From half throttle to full throttle the RPM did not change and the aircraft could not sustain vertical climb. It was obvious that it was overpropped.
I switched glow plugs from the O.S. 8 to an Enya No. 6 and gained about 200 RPM with stronger acceleration.
Here is my set up...HHHEEELLLPPP!!!
15% Cool Power with 1/2 gallon burned
16-6 APC @9300 RPM
Enya No.6
Stock Exhaust with no extension.
Engine is mounted slightly below flat.
Thanks,
Propwrench
I am glad to see this post... hopefully it will help me also. I am running a 120AX in a Showtime and am about ready to drop kick this engine! Very dissapointed so far and almost wish for my old reliable Supertigre G-90!
After a conservative break in I am running a 16-6 APC and it tachs at 93-9400 after warm up but as soon as it lifts off it SIGNIFICANTLY drops. The aircraft acts like it is severly underpowered... it struggles to sustain vertical and BARELY hovers!
I tried a 16-4 APC trying to lighten the load that revved 10200, way above its intended RPM range. The engine did maintain a consistent RPM but the aircraft struggled to flatten out and fly obviously due to the low pitch and not being able to harness any power.
In an effort to load the engine more, tonight I bolted a 16-8 APC onto and gave it a shot. It tached at 8900 RPM before take off but REALLY dropped off after it went airborne. From half throttle to full throttle the RPM did not change and the aircraft could not sustain vertical climb. It was obvious that it was overpropped.
I switched glow plugs from the O.S. 8 to an Enya No. 6 and gained about 200 RPM with stronger acceleration.
Here is my set up...HHHEEELLLPPP!!!
15% Cool Power with 1/2 gallon burned
16-6 APC @9300 RPM
Enya No.6
Stock Exhaust with no extension.
Engine is mounted slightly below flat.
Thanks,
Propwrench
I think your motor is either:
1) starving for fuel (you may have done some power robbing damage already)
2) Running hot because improper cooling
My best guess it that if you cant get it to act up on the ground then you have a fuel delivery problem in the air.
My favorite prop for the best thrust (all flying other than racing) is a wood SK 17x6 or BME 17x6 followed by the 16x6 (about 1/2 the weight of APC)
____________
I don't know how the stock "power box" could be tuned in any way? By the RPM figures I see it is restricting performance over a free flowing pitts.
08-11-2006, 02:27 PM
#12
RE: OS 120 AX Prop Size ?
For what it's worth,,,, I want one of these so i called the not so local hobby shop to buy one and have it sent to me. The owner said he had one but would not sell it as there is a problem with them and this is what he said... The engines are over heating when in flight. IF there hanging out in the breeze they seem to be fine but if in a cowl they just get to hot... He the owner said there are two OS factory guys that fly at the club and told him OS is working on changing the head to get better cooling. Well anyway we went round and round and i ended up getting a 1.60FX BUT i do want a 1.20AX and will have one in about 2 weeks
from tower.
Pat
from tower.Pat
08-11-2006, 04:19 PM
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RE: OS 120 AX Prop Size ?
I am still breaking mine in , sitting in an Excelleron 90, and I must say this thing feels dangerously powerful. He does want to take his time to break in, idle gets better the more he runs; Powermaster 15% and just an Airscrew 16x8. He is cowled and it does seem that he radiates alot of heat, haven't put an infared thermometer on him yet.
08-12-2006, 06:27 AM
#15
RE: OS 120 AX Prop Size ?
Sewerdude
Sorry for getting back so late. It's been a long time since I've checked it and I don't really remember what the rpm was with the APC 17X6 prop but 8800 rpm rings a bell. I could be mixing up rpm readings with my gasser running the same prop.
Sorry for getting back so late. It's been a long time since I've checked it and I don't really remember what the rpm was with the APC 17X6 prop but 8800 rpm rings a bell. I could be mixing up rpm readings with my gasser running the same prop.
08-12-2006, 10:58 PM
#16
RE: OS 120 AX Prop Size ?
ORIGINAL: BankYank
For what it's worth,,,, I want one of these so i called the not so local hobby shop to buy one and have it sent to me. The owner said he had one but would not sell it as there is a problem with them and this is what he said... The engines are over heating when in flight. IF there hanging out in the breeze they seem to be fine but if in a cowl they just get to hot... He the owner said there are two OS factory guys that fly at the club and told him OS is working on changing the head to get better cooling. Well anyway we went round and round and i ended up getting a 1.60FX BUT i do want a 1.20AX and will have one in about 2 weeks from tower.
Pat
For what it's worth,,,, I want one of these so i called the not so local hobby shop to buy one and have it sent to me. The owner said he had one but would not sell it as there is a problem with them and this is what he said... The engines are over heating when in flight. IF there hanging out in the breeze they seem to be fine but if in a cowl they just get to hot... He the owner said there are two OS factory guys that fly at the club and told him OS is working on changing the head to get better cooling. Well anyway we went round and round and i ended up getting a 1.60FX BUT i do want a 1.20AX and will have one in about 2 weeks
from tower.Pat
08-13-2006, 10:02 AM
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RE: OS 120 AX Prop Size ?
I have this motor in a Cermark 25% Pitts, with an APC 16x8 prop, and a Bisson Pitts muffler. I crimped one of the muffler tubes a little to restrict it due to never being able to get it to 4 cycle on break in and now it gets my Pitts in th air in about 10 feet, and will fly it around at 1/4 throttle. No heat problems, motor and muffler are completely inside the cowl.
08-14-2006, 09:25 AM
#18
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RE: OS 120 AX Prop Size ?
The O.S. Max 1.20 AX engine does not have a heating problem that we know of. Overheating is usually caused by too much load, something causing it to go lean, low-oil fuel, or a lack of proper airflow through the fins on the cylinder. Many cowled aircraft do not have proper airflow, even though the modeler has made a large entry and exit for air. If you can see the air exit when you look into the air inlet, then the air is not passing over the engine and cooling it. You MUST make sure that any air entering the cowling actually passes through the engine's fins, so that may mean that you have to make baffles to insure this. This becomes more and more necessary as airplanes get larger, and the engine is smaller and smaller in its size relationship to the interior of the cowling.
08-14-2006, 10:57 AM
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RE: OS 120 AX Prop Size ?
absolute right cowl opening has to be enlarged and baffles to direct flow across the head and barrel is a must ,and the exit is equally imp which many ppl overlook. i have cooked, destroyed one os160 in a WM extra by not doing the above , just by dremel sanding the opening and fixing a baffle , i have noticed a much cooler running motor that will last forever (almost) and o ys once u cook the motor its never the same no matter what . so take the effort and do the mods and ull c the diff.
08-28-2006, 12:03 PM
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RE: OS 120 AX Prop Size ?
I am planning to put the 1.20 AX in a Funtana 90. What is the best 3D prop for this combination? I was looking at either the 16 x 4W APC or 18 x 6W APC.
Regarding issues with the engine:
I had the 1.20 AX in a laser 200 and flew great without heating up. After around 12 flights in the second flight of that day the engine blew the head gasket and 3 bolts from the head. Since I was getting ready for land I was flying slow and somewhat low and the rest is history [:@]
- I lost my airplane- I got the engine replaced with the the recommendation to check that the bolts are tight after a few flights (never heard of that in a "reliable" OS). One friend at the field bought one and after my story he checked his on time (before flying), guess..... almost all bolts were loose!!!!
Regarding issues with the engine:
I had the 1.20 AX in a laser 200 and flew great without heating up. After around 12 flights in the second flight of that day the engine blew the head gasket and 3 bolts from the head. Since I was getting ready for land I was flying slow and somewhat low and the rest is history [:@]
- I lost my airplane- I got the engine replaced with the the recommendation to check that the bolts are tight after a few flights (never heard of that in a "reliable" OS). One friend at the field bought one and after my story he checked his on time (before flying), guess..... almost all bolts were loose!!!!
08-28-2006, 02:36 PM
#23
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RE: OS 120 AX Prop Size ?
ORIGINAL: alvarogn
I am planning to put the 1.20 AX in a Funtana 90. What is the best 3D prop for this combination? I was looking at either the 16 x 4W APC or 18 x 6W APC.
I am planning to put the 1.20 AX in a Funtana 90. What is the best 3D prop for this combination? I was looking at either the 16 x 4W APC or 18 x 6W APC.
Are you sure you have got the numbers right???
You would need twice as much engine to spin the 18x6W, than you would to spin the 16x4W...
08-28-2006, 07:22 PM
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RE: OS 120 AX Prop Size ?
Thank you,
I kind of knew it was not right thinking about sucha a big prop but I did not find a "W" prop between the 16 and teh 18. I have read that most people are using either a 16 x 8 or a 17 x 6 for 3D for the funtana 120ax. The comments are that the 16 x 4 W is spec for a 120 4 cycle and is maybe small for this 120 ax. Do you think then that a 17 x 6 might be the best option?
I kind of knew it was not right thinking about sucha a big prop but I did not find a "W" prop between the 16 and teh 18. I have read that most people are using either a 16 x 8 or a 17 x 6 for 3D for the funtana 120ax. The comments are that the 16 x 4 W is spec for a 120 4 cycle and is maybe small for this 120 ax. Do you think then that a 17 x 6 might be the best option?
08-28-2006, 10:50 PM
#25
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RE: OS 120 AX Prop Size ?
Alvaro,
The OS1.20FX is stated to spin a 16x8-10 prop.
A 17x6 prop will offer the same load, so there is no reason it would not spin this size.
For better acceleration, stay away from inertially heavy GFN props, like APC and use much lighter, better wood props.
The older Zinger and MA wood are not very efficient. Better ones are made by Bolly, 3W, Menz.
The new Zinger Pro are reasonable.
The OS1.20FX is stated to spin a 16x8-10 prop.
A 17x6 prop will offer the same load, so there is no reason it would not spin this size.
For better acceleration, stay away from inertially heavy GFN props, like APC and use much lighter, better wood props.
The older Zinger and MA wood are not very efficient. Better ones are made by Bolly, 3W, Menz.
The new Zinger Pro are reasonable.