rmenter
Apr 15, 2004, 02:00 PM
!Introduction
| spec2
| @906827
|> <b>Displacement:</b> |< .44 cu in (7.5cc)
|> <b>Bore:</b> |< .866” (22mm)
|> <b>Stroke:</b> |< .772” (20mm)
|> <b>Output:</b> |< 1.65bhp @ 16K RPM
|> <b>RPM Range:</b> |< 2K-17K
|> <b>Weight w/ muff:</b> |< 17.2 oz (489g)
|> <b>Sugg Props:</b> |< 10.5x6, 11x6-8, 12x6-7
|> <b>Tested Props:</b> |< All suggested!
|> <b>Recomm. Fuel:</b> |< 10% nitro, 18% oil
|> <b>Tested Fuel:</b> |< 10% nitro “high castor”
|> <b>Includes:</b> |< A3 plug, E3010 muffler, silicon tube, manual
|> <b>Test Plane:</b> |< World Models SS40, 5.5 lbs
|> <b>Manufacturer:</b> |< <a href="http://www.osengines.com">OS Engines</a>
|> <b>Available online from:</b> |< <a href="http://www.towerhobbies.com"</a>Tower Hobbies</a>
@906828:Old reliable.
@906829:The new contender.
@906830:The new engine has the identical bolt pattern. THANK YOU OS!
New engine? Everyone wants to know all about it! Recently, I had the opportunity to fly one and see just what’s “new” about the OS Max-46 AX engine. OS is retiring the venerable 46 FX, an engine I’ve flown for years. “Don’t worry,” states the ad, “there’s still a lot of the .46 FX in the .46 AX.” They are referring to the dual bearings, long crankshaft and locknut assembly, the ABL cylinder liner, and the identical bolt patterns. This last feature made it easy for me to fly both engines using one plane for the purpose of comparison.
As it happens, I have been flying a .46 FX on a World Models Super Sport 40. Since I am comfortable with this plane/engine combination, I felt it made a great test platform to evaluate the performance of the two engines.
@906831:The FX’s 873 muffler was more streamlined … and louder.
@906832:The new E3010 muffler is more boxy…and quieter.
Before mounting the new AX, I compared it to its older brother. The AX looks quite like the FX…the engine configurations and parts locations are similar, but from there on, things begin to look different. The new E-3010 muffler is a bit boxier looking than that of the FX. The high-end needle valve sports a new bracket and composite housing, which was designed to prevent heat from the head from affecting needle settings.
@906833:Notice AX has no throttle-stop-screw.
Another noticeable difference: there is no throttle-stop screw poking up from the top of the carburetor barrel. I liked this feature. On my FX, this little beastie requires periodic checking to ensure that the spring-loaded screw doesn’t back out over time, changing engine performance. On the AX, the “rotor guide screw” as it is now called, screws into the back of the carb housing, presumably because it shouldn’t require frequent adjustment.
@906834:A close-up of the
@906835:2 carburetors.
Because of its new location, one should remove the carburetor to tighten or loosen the slotted-head screw without chewing it up. By the way, the carburetor fixing screws on my FX need periodic checking to ensure they are tight; otherwise, they have a habit of coming loose at times, which changes the fuel mixture and kills performance. The arrangement on the AX appears to be much the same
@906836:The new needle
The newly mounted high-speed needle valve offers two new features. The mounting bracket permits convenient changing of the valve position from horizontal to vertical, and the needle valve and housing are re-designed.
Two Phillips-head screws hold the needle valve to the bracket; two screws hold the bracket to the engine. I found it easy to make the change, although I returned it to the factory-set position of horizontal to accommodate the test plane.
The AX needle-valve housing is made of a composite material and is said to prevent engine heat from affecting needle settings. After break-in and during my test flights, I found needle settings to remain steady. Incidentally, the low-speed needle valve has a new taper, designed to reduce “surge” during throttle-up. Once set, the AX ran smoothly and did not hesitate during climbs, rolls or aerobatic moves. It responded smoothly whenever I gave it full throttle, even after “coasting” at idle. <I>(Enjoy its great new sound in the 2 videos, below.)</I>
Time needed to set both low and high-end adjustments was minimal. I have found my FX to be rock steady once these adjustments have been made. Most changes in temperature and humidity require only one or two clicks of high end (lean or rich, depending on the change in weather) with no change needed to the low end. In the short time I have worked with the AX, it seems to behave just as reliably. As someone who prefers to fly rather than to tinker, this feature has made for many enjoyable flying days.
One other feature I noticed is the cylinder head is fastened with only four screws on the AX, v. six on the FX. I think only time will tell whether this arrangement is better, although it appears that removing and replacing the head will be easier. OS brags that the new design automatically centers, levels and seats the head upon replacement.
!!FX survived a crash.
@906837:46 FX shows bruise where engine hit the concrete.
One aside here, I once lost a plane in a mid-air. The same FX used in this evaluation was onboard when another flyer put his plane right through the middle of mine. I was flying inverted circles at the time. The wing broke in two and the fuselage came down like the proverbial lawn dart onto the tarmac. One result of the crash was that the needle-valve assembly (which is a part of the engine rear cover assembly) broke off. However, the engine ran fine after the crash, and after fitting it with a new rear cover, the FX was back in business. Perhaps the new bracket will reduce the potential for that kind of damage in crash situations.
</div>
!SPECIFICATIONS:
|
|> <b>Engine:</b> |< <b>.46 AX</b> |< <b>.46 FX</b>
|> <b>Displacement:</b> |< .455 cu in (7.45cc) |< .455 cu in (7.45cc)
|> <b>Bore:</b> |< .866 cu in (22.0mm)|< .866 cu in (22.0mm)
|> <b>Stroke:</b> |< .772 cu in (19.6mm)|< .772 cu in (19.6mm)
|> <b>RPM output:</b> |< 2,000-17,000 |< 2,000-17,000
|> <b>BHP @ rpm:</b> |< 1.65@16K |< 1.62@16K
|> <b>Weight (oz):</b> |< 13.2 w/o muffler|< 13.2 w/o muffler
|> <b>Recomm props:</b> |< 10.5x6,11x6-8,12x6-7|< 10.5x6,11x6-7,12x6-7
!Set-up
@906838:A nicely packaged engine, as always.
The AX comes nicely packed with an OS plug, silicon tubing, the muffler and bolts, and an owner’s instruction manual. OS motors always come well packaged. This one’s no exception. Mounting the AX on the test plane was a snap, because, as mentioned previously, its bolt patterns are identical to those of the .46 FX. The throttle linkage is in virtually the same position too, so that took no time at all to hook up and re-adjust. I popped off the FX and, using the same bolts, I installed the AX in less than 10 minutes.
!Break-in
!!Day one - Sunny and 70.
@906839:I ran 6 tanks before flight-testing began.
I brought the plane with the engine already mounted to the field. I like to break new engines in with 5% nitro high castor oil glow fuel. Break-in was simple. Following the instructions in the owner’s manual, I fueled up and cranked the AX. It started right up and ran well, not quitting until the last of the fuel was gone and the engine leaned out and stopped. I ran 6 tanks of fuel through it on the ground before flying it. While the directions call for only one tank to be run while varying the needle valve every 10 seconds, I ran the first two, as is my practice: varying 2 - 4 cycle operation every 10 seconds for the entire tank. I ran the next three tanks “rich” and the final tank, gradually leaning out the high end until it was just slightly rich.
!Performance
!!Day One Continues
Next, I fueled up with 10% glow fuel, re-adjusted the high end, and flew the plane. The owner’s manual says the low-end factory setting should be good, but it was a bit rich and hesitated when I throttled up quickly. So I landed and tweaked it, leaning it out in very small increments, ending up about 1/4 turn leaner. Here it ran fine and responded very well. The manual also says to avoid flying nose-up for the first three or four flights, so I did. I couldn’t help sneaking in an occasional snap roll, or a split-ess to change direction. All the while, the AX was smooth and responsive. After several flights, an impending storm front announced its imminent arrival with gusty winds and an occasional droplet of rain, so I called it a day and packed up to go home.
!!Day Two - Windy and 40.
I Arrived at the field around 8 a.m. and had the place to myself. From the temperature, humidity, and barometer differences, it was clear that the front has passed through during the night. I started the engine cold; it turned over right away, idling easily even after I removed the glow-plug starter and with no extended warm-up. I noticed the tight, clean sound of the new engine as it purred at idle. With the increased humidity, it needed but one click rich on the high end to resume the slightly rich running of the previous day’s workout. With a 10-12 knot wind blowing almost straight down the runway, I throttled up the engine and took off.
+906840:Video of the engine’s sweet starting performance.
+906841:Split-ess, aerobatics, and a smooth clean landing without a burble.
<I>Videos by Matt Cernigliaro. Great job, and thanks, Matt!</I>
The wind was becoming stronger with each minute of the flight, but the OS ran steady and strong. To see how the AX compared to my FX, I did a few snap rolls and split-ess turns into the wind. The AX performed smoothly and without hesitation. I turned the plane over and flew inverted. No problems or hiccoughs. The OS ran smooth and the RPMs did not vary as I flew a circular pattern around the field a few times. I tried several high-speed low passes to check out the new muffler. The AX does run somewhat quieter than my FX. The new muffler has a softer, mellower tone. As the winds increased, and my fingers began to numb, I lined up for a landing and brought the plane down. The engine, once shut off, was just barely warm to the touch.
!!Day 3
Another not-so nice day. Gray and gusty, to about 15 knots, but flyable and an opportunity to test the AX power. The wind was switching constantly from a quartering wind to a crossing wind and other pilots were having debates about which way to take off. Once we decided, I taxied out onto the runway and lined up for take-off. The AX took full throttle without a beat and climbed into the wind. I flew several loops around the field at full throttle and the AX began to vary a bit, so I landed and richened the high-end one click. Climbing again, the AX was rock steady and smooth as the day before. I did some slow passes to see how the engine would do in the wind. It ran steady despite the buffeting from the gusts. I nailed the throttle to gain airspeed and the AX responded quickly and smoothly. High passes were also fine, although the turbulence caused the plane to bump around quite a bit. With the wind quartering, landings were a bit bumpy and the plane weather-vaned into the wind when I cut the throttle.
!Props - performance
The AX does fine with the suggested props. I needed only minor needle-valve adjustments after the change-outs. As with the FX, the AX runs predictably and reliably. It’s easy to adjust and a pleasure to fly. I flew the 10.5x6, the 11x6, and 12x6, all on the same plane, so this was not a true test of the engine under different conditions, but each time, the engine did just fine, achieving the expected result of pulling power or increased speed. The AX did not seem to be working any harder as I switched through the range of props. However, the AX seems to like the 11 x 6 best of all, running a bit cooler than with the 12 x 6 and being up to the task of pulling the Super Sports 40 along quickly. With the 11 x 6 prop, I can almost hold the plane in a hover and it will climb almost out of sight.
!Summary
*Key Features List
*Same ABL lining as 46FX
*New, boxier, quieter muffler
*New, tapered low-end needle
*Redesigned liner for more consistent power
*New high-speed needle bracket for easier side-mounting
*New high-speed needle bracket decreases heat transfer for more consistent tuning
*O-rings on both needles
*Rotor guide screw instead of stop screw to minimize user maintenance
*Longer crankshaft for better contact with thicker props/spinners
!!Flight Conclusions
I have flown OS two- and four-stroke engines, and they have proven to be quite reliable and ready to work with relatively little care. During the warm season, I often put them away after a weekend of flying without applying after-run oil. The next week, they start right up. I fly them hard and they perform without constant adjustments. Once set, they continue to run well, and usually require only minor tweaks on the high end. They idle smoothly without quitting, and
transition smoothly as well. While I have only a few days’ experience with the AX, it is already demonstrating that it a great running, well-engineered engine.
| spec2
| @906827
|> <b>Displacement:</b> |< .44 cu in (7.5cc)
|> <b>Bore:</b> |< .866” (22mm)
|> <b>Stroke:</b> |< .772” (20mm)
|> <b>Output:</b> |< 1.65bhp @ 16K RPM
|> <b>RPM Range:</b> |< 2K-17K
|> <b>Weight w/ muff:</b> |< 17.2 oz (489g)
|> <b>Sugg Props:</b> |< 10.5x6, 11x6-8, 12x6-7
|> <b>Tested Props:</b> |< All suggested!
|> <b>Recomm. Fuel:</b> |< 10% nitro, 18% oil
|> <b>Tested Fuel:</b> |< 10% nitro “high castor”
|> <b>Includes:</b> |< A3 plug, E3010 muffler, silicon tube, manual
|> <b>Test Plane:</b> |< World Models SS40, 5.5 lbs
|> <b>Manufacturer:</b> |< <a href="http://www.osengines.com">OS Engines</a>
|> <b>Available online from:</b> |< <a href="http://www.towerhobbies.com"</a>Tower Hobbies</a>
@906828:Old reliable.
@906829:The new contender.
@906830:The new engine has the identical bolt pattern. THANK YOU OS!
New engine? Everyone wants to know all about it! Recently, I had the opportunity to fly one and see just what’s “new” about the OS Max-46 AX engine. OS is retiring the venerable 46 FX, an engine I’ve flown for years. “Don’t worry,” states the ad, “there’s still a lot of the .46 FX in the .46 AX.” They are referring to the dual bearings, long crankshaft and locknut assembly, the ABL cylinder liner, and the identical bolt patterns. This last feature made it easy for me to fly both engines using one plane for the purpose of comparison.
As it happens, I have been flying a .46 FX on a World Models Super Sport 40. Since I am comfortable with this plane/engine combination, I felt it made a great test platform to evaluate the performance of the two engines.
@906831:The FX’s 873 muffler was more streamlined … and louder.
@906832:The new E3010 muffler is more boxy…and quieter.
Before mounting the new AX, I compared it to its older brother. The AX looks quite like the FX…the engine configurations and parts locations are similar, but from there on, things begin to look different. The new E-3010 muffler is a bit boxier looking than that of the FX. The high-end needle valve sports a new bracket and composite housing, which was designed to prevent heat from the head from affecting needle settings.
@906833:Notice AX has no throttle-stop-screw.
Another noticeable difference: there is no throttle-stop screw poking up from the top of the carburetor barrel. I liked this feature. On my FX, this little beastie requires periodic checking to ensure that the spring-loaded screw doesn’t back out over time, changing engine performance. On the AX, the “rotor guide screw” as it is now called, screws into the back of the carb housing, presumably because it shouldn’t require frequent adjustment.
@906834:A close-up of the
@906835:2 carburetors.
Because of its new location, one should remove the carburetor to tighten or loosen the slotted-head screw without chewing it up. By the way, the carburetor fixing screws on my FX need periodic checking to ensure they are tight; otherwise, they have a habit of coming loose at times, which changes the fuel mixture and kills performance. The arrangement on the AX appears to be much the same
@906836:The new needle
The newly mounted high-speed needle valve offers two new features. The mounting bracket permits convenient changing of the valve position from horizontal to vertical, and the needle valve and housing are re-designed.
Two Phillips-head screws hold the needle valve to the bracket; two screws hold the bracket to the engine. I found it easy to make the change, although I returned it to the factory-set position of horizontal to accommodate the test plane.
The AX needle-valve housing is made of a composite material and is said to prevent engine heat from affecting needle settings. After break-in and during my test flights, I found needle settings to remain steady. Incidentally, the low-speed needle valve has a new taper, designed to reduce “surge” during throttle-up. Once set, the AX ran smoothly and did not hesitate during climbs, rolls or aerobatic moves. It responded smoothly whenever I gave it full throttle, even after “coasting” at idle. <I>(Enjoy its great new sound in the 2 videos, below.)</I>
Time needed to set both low and high-end adjustments was minimal. I have found my FX to be rock steady once these adjustments have been made. Most changes in temperature and humidity require only one or two clicks of high end (lean or rich, depending on the change in weather) with no change needed to the low end. In the short time I have worked with the AX, it seems to behave just as reliably. As someone who prefers to fly rather than to tinker, this feature has made for many enjoyable flying days.
One other feature I noticed is the cylinder head is fastened with only four screws on the AX, v. six on the FX. I think only time will tell whether this arrangement is better, although it appears that removing and replacing the head will be easier. OS brags that the new design automatically centers, levels and seats the head upon replacement.
!!FX survived a crash.
@906837:46 FX shows bruise where engine hit the concrete.
One aside here, I once lost a plane in a mid-air. The same FX used in this evaluation was onboard when another flyer put his plane right through the middle of mine. I was flying inverted circles at the time. The wing broke in two and the fuselage came down like the proverbial lawn dart onto the tarmac. One result of the crash was that the needle-valve assembly (which is a part of the engine rear cover assembly) broke off. However, the engine ran fine after the crash, and after fitting it with a new rear cover, the FX was back in business. Perhaps the new bracket will reduce the potential for that kind of damage in crash situations.
</div>
!SPECIFICATIONS:
|
|> <b>Engine:</b> |< <b>.46 AX</b> |< <b>.46 FX</b>
|> <b>Displacement:</b> |< .455 cu in (7.45cc) |< .455 cu in (7.45cc)
|> <b>Bore:</b> |< .866 cu in (22.0mm)|< .866 cu in (22.0mm)
|> <b>Stroke:</b> |< .772 cu in (19.6mm)|< .772 cu in (19.6mm)
|> <b>RPM output:</b> |< 2,000-17,000 |< 2,000-17,000
|> <b>BHP @ rpm:</b> |< 1.65@16K |< 1.62@16K
|> <b>Weight (oz):</b> |< 13.2 w/o muffler|< 13.2 w/o muffler
|> <b>Recomm props:</b> |< 10.5x6,11x6-8,12x6-7|< 10.5x6,11x6-7,12x6-7
!Set-up
@906838:A nicely packaged engine, as always.
The AX comes nicely packed with an OS plug, silicon tubing, the muffler and bolts, and an owner’s instruction manual. OS motors always come well packaged. This one’s no exception. Mounting the AX on the test plane was a snap, because, as mentioned previously, its bolt patterns are identical to those of the .46 FX. The throttle linkage is in virtually the same position too, so that took no time at all to hook up and re-adjust. I popped off the FX and, using the same bolts, I installed the AX in less than 10 minutes.
!Break-in
!!Day one - Sunny and 70.
@906839:I ran 6 tanks before flight-testing began.
I brought the plane with the engine already mounted to the field. I like to break new engines in with 5% nitro high castor oil glow fuel. Break-in was simple. Following the instructions in the owner’s manual, I fueled up and cranked the AX. It started right up and ran well, not quitting until the last of the fuel was gone and the engine leaned out and stopped. I ran 6 tanks of fuel through it on the ground before flying it. While the directions call for only one tank to be run while varying the needle valve every 10 seconds, I ran the first two, as is my practice: varying 2 - 4 cycle operation every 10 seconds for the entire tank. I ran the next three tanks “rich” and the final tank, gradually leaning out the high end until it was just slightly rich.
!Performance
!!Day One Continues
Next, I fueled up with 10% glow fuel, re-adjusted the high end, and flew the plane. The owner’s manual says the low-end factory setting should be good, but it was a bit rich and hesitated when I throttled up quickly. So I landed and tweaked it, leaning it out in very small increments, ending up about 1/4 turn leaner. Here it ran fine and responded very well. The manual also says to avoid flying nose-up for the first three or four flights, so I did. I couldn’t help sneaking in an occasional snap roll, or a split-ess to change direction. All the while, the AX was smooth and responsive. After several flights, an impending storm front announced its imminent arrival with gusty winds and an occasional droplet of rain, so I called it a day and packed up to go home.
!!Day Two - Windy and 40.
I Arrived at the field around 8 a.m. and had the place to myself. From the temperature, humidity, and barometer differences, it was clear that the front has passed through during the night. I started the engine cold; it turned over right away, idling easily even after I removed the glow-plug starter and with no extended warm-up. I noticed the tight, clean sound of the new engine as it purred at idle. With the increased humidity, it needed but one click rich on the high end to resume the slightly rich running of the previous day’s workout. With a 10-12 knot wind blowing almost straight down the runway, I throttled up the engine and took off.
+906840:Video of the engine’s sweet starting performance.
+906841:Split-ess, aerobatics, and a smooth clean landing without a burble.
<I>Videos by Matt Cernigliaro. Great job, and thanks, Matt!</I>
The wind was becoming stronger with each minute of the flight, but the OS ran steady and strong. To see how the AX compared to my FX, I did a few snap rolls and split-ess turns into the wind. The AX performed smoothly and without hesitation. I turned the plane over and flew inverted. No problems or hiccoughs. The OS ran smooth and the RPMs did not vary as I flew a circular pattern around the field a few times. I tried several high-speed low passes to check out the new muffler. The AX does run somewhat quieter than my FX. The new muffler has a softer, mellower tone. As the winds increased, and my fingers began to numb, I lined up for a landing and brought the plane down. The engine, once shut off, was just barely warm to the touch.
!!Day 3
Another not-so nice day. Gray and gusty, to about 15 knots, but flyable and an opportunity to test the AX power. The wind was switching constantly from a quartering wind to a crossing wind and other pilots were having debates about which way to take off. Once we decided, I taxied out onto the runway and lined up for take-off. The AX took full throttle without a beat and climbed into the wind. I flew several loops around the field at full throttle and the AX began to vary a bit, so I landed and richened the high-end one click. Climbing again, the AX was rock steady and smooth as the day before. I did some slow passes to see how the engine would do in the wind. It ran steady despite the buffeting from the gusts. I nailed the throttle to gain airspeed and the AX responded quickly and smoothly. High passes were also fine, although the turbulence caused the plane to bump around quite a bit. With the wind quartering, landings were a bit bumpy and the plane weather-vaned into the wind when I cut the throttle.
!Props - performance
The AX does fine with the suggested props. I needed only minor needle-valve adjustments after the change-outs. As with the FX, the AX runs predictably and reliably. It’s easy to adjust and a pleasure to fly. I flew the 10.5x6, the 11x6, and 12x6, all on the same plane, so this was not a true test of the engine under different conditions, but each time, the engine did just fine, achieving the expected result of pulling power or increased speed. The AX did not seem to be working any harder as I switched through the range of props. However, the AX seems to like the 11 x 6 best of all, running a bit cooler than with the 12 x 6 and being up to the task of pulling the Super Sports 40 along quickly. With the 11 x 6 prop, I can almost hold the plane in a hover and it will climb almost out of sight.
!Summary
*Key Features List
*Same ABL lining as 46FX
*New, boxier, quieter muffler
*New, tapered low-end needle
*Redesigned liner for more consistent power
*New high-speed needle bracket for easier side-mounting
*New high-speed needle bracket decreases heat transfer for more consistent tuning
*O-rings on both needles
*Rotor guide screw instead of stop screw to minimize user maintenance
*Longer crankshaft for better contact with thicker props/spinners
!!Flight Conclusions
I have flown OS two- and four-stroke engines, and they have proven to be quite reliable and ready to work with relatively little care. During the warm season, I often put them away after a weekend of flying without applying after-run oil. The next week, they start right up. I fly them hard and they perform without constant adjustments. Once set, they continue to run well, and usually require only minor tweaks on the high end. They idle smoothly without quitting, and
transition smoothly as well. While I have only a few days’ experience with the AX, it is already demonstrating that it a great running, well-engineered engine.