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| Engines Discuss engines |
Topic Review (Newest First)
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| 10-21-2011 05:30 PM | ||
| AJCoholic |
Re: OS 95AX good or not so good Quote:
As for the .95 AX, it is designed to turn larger props, and not run small props at a high rpm. Nathan is flying the engine I tested for Fly RC nearly two seasons ago and it is a sweet running engine. I think, however, with the size of the newer 1.20AX being only 2 oz heavier, probably more of those sold? WHo knows... but all the AX line (I have run every one but the 1.20) are excellent. AJC |
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| 10-20-2011 10:30 PM | ||
| Cougar429 |
Re: OS 95AX good or not so good I've run lots of OS 2-strokes over the years and the newest in the fleet are a pair of 55AX's. All I can say is if the 95 performs in the same fashion it should be a real stump puller. The reason I originally noted the 4-stroke may be a better fit is that it is able to swing a large prop to help clear the huge cowl diameter. If the prop is matched to the motor you should be able to get more than enough thrust for your needs. On that note, I have 3 OS 90Surpass 4-strokes and Saitos in the 91-150 range. Can definitely say if you decide to bolt one on either choice is good, but kind of tilting towards the latter when it comes to power, (personally I like the looks of the Saitos more, but that's just me). DO335, I agree with your assesment of toe in, but everything I ever knew points the other way when it comes to prop dynamics. It is true prop efficiency drops dramatically when near or at the transonic/supersonic boundary, (unless designed for it as with the real Harvard/AT-6) but the thinking the outer portion is generally useless when operated normally is incorrect. There are lots of factors to contend with, too many to list here and definitely off topic. As for experience on which to base this thinking, in my past life I was a fixed wing and heli pilot/AME. |
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| 10-20-2011 07:52 PM | ||
| Arn |
Re: OS 95AX good or not so good I forgot that I have an OS 91 .... F? .... in a Minnow (pylon racer) .... it does behave a bit differently .. seems to take a while to spool up to top rpm .... runs fine ... been reliable .... it's just different .... probably my setup .... but I'll still say the OS engines .... at least the 2S line have always been a winner .... Good Luck .... |
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| 10-20-2011 07:26 PM | ||
| gwilken |
Re: OS 95AX good or not so good I do have 2 55AX myself and they have been perfect right out of the box. Easy to set and rock solid in the air. Thats why I was a little suprised to see so little about the 95AX and some of it not so good. As for it being to big for this aiframe I am not too concerned. The kit is rated or 60 - 90 2 strokes so the 95 is not that much bigger. I believe it is lighter than the OS Max 90 FSR I run on my GP Skybolt. My interest in the 95 AX is based on my experience with the 55 AX. I am looking for speed more than power. This is a warbird not a 3D bird. I know the sound of a 4 stroke would likly suit it better and it would also have more than enough speed. At this point I have not made a definite descision. The amount of fuel burn is not a concern to me. |
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| 10-20-2011 03:19 PM | ||
| Arn |
Re: OS 95AX good or not so good Hi Gary .... back to your original query .... I don't have an airframe with a .95AX .... but I do have a twin with 55ax's, 5 with 75AX's and 3 with 1.25AX's ..... from 1 to 5 years old .... all have been excellent performers and given me no grief .... if OS has put the same amount of QA into the 95AX as the rest of the AX series and I'm sure they did ..... I predict you will be pleased with it. As to it being too much for your selected airframe .... maybe .... one of my favorite expressions is ... "you can always throttle back a bit" .... IMHO .... it's something you don't have to worry about "knowing" you have the power to ..... rather then "hoping" you have the power to .... If you can get the balance right and handle a the bit of extra weight .... and the resulting need for a bit more airspeed .... I'd say go with it .....  ... Arn |
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| 10-20-2011 03:04 PM | ||
| Thunder Chicken |
Re: OS 95AX good or not so good Quote: "let me assure you that tow out is the last thing in the world that you want. You need a bit of toe in." A Big +1 But this thread is about engines lets not get off track! I'd go with a four stroke as well. Maybe even a 20cc gas? or the Saito FG-14/20?!! |
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| 10-20-2011 02:40 PM | ||
| DO335 |
Re: OS 95AX good or not so good Quote:
Well, don't trust me and Harvey... go try the two configurations with the same plane and see for yourself what happens, especially in a cross wind. Make certain that you do this with a model and not a full size plane, unless you have a hefty insurance policy which is fully paid up. |
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| 10-20-2011 02:30 PM | ||
| DO335 |
Re: OS 95AX good or not so good Quote:
Your suggestion of a suitable 4 stroke is a great solution. |
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| 10-20-2011 09:32 AM | ||
| kip51035 |
Re: OS 95AX good or not so good On real radial engined A/C the air goes through the fins and out the back of the cowl. The firewall is rounded to pre-mote smooth exit of the airflow. I skimmed through Cougar's AT6 thread the real A/C was notorious for ground loops. If you put some TOW OUT on your main wheels it will lessen the chances of a ground loop. When it rears up on one wheel it tends to drag the high wing down. Think about it. |
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| 10-20-2011 08:37 AM | ||
| Cougar429 |
Re: OS 95AX good or not so good I find on scale projects the 4-stroke sounds much more realistic. In a lot of cases it is able to swing a larger diameter prop slower, which also fits the scale look better. On some of the old warbirds the cowl diameter is huge, so it is only the prop hanging out beyond that doing any work to pull it along. If you want to have a look, I started a thread on my Harvard, (T/F Gold AT-6 Texan) that shows some of the concerns with that kind of installation. I would think the two would be similar. Along with the prop you have to address adequate cooling: https://www.rccanada.ca/rccforum/showthread.php?t=116111 p.s. I would add that all motors may have a bad manufacturing run, (OS is generally pretty good, except for some of their plated cylinders flaking off) but perhaps along with the forementioned problems some of those with the 95's comes from installation, (ie. inverted). |
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