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OS AX-GMS-Magnum-Tower - 12/30/2003 6:38:48 PM   
Ed_Moorman



Posts: 3673
Joined: 1/5/2002
From: Shalimar, FL, USA
Status: offline 		Mini Comparison Test: OS .46AX GMS .47 Magnum .52XLS Tower .46

I mentioned in an earlier thread I would run a short test when I got the chance and here are the results.

Prop: APC 12.25-3.75 Fun Fly
Fuel: Omega 10% Castor blend
Same day, same time, same prop, same test stand except for Tower which was mounted in a Fazer profile on floats.
Temperature: About 60 deg., low humidity.


OS .46 AX 12,400
Magnum .52XLS 12,800
GMS .47 12,100
Tower .46 11,900

Notes:
1. All rpms were max steady rpm. 1 run only.
2. All engines were new with a short bench break-in with the following exceptions.
a. The Magnum had 3 flights of about 8 minutes each since its break-in.
b. The Tower is old and probably over-the-hill. I bought it when they first came out. It has been in several planes.
3. The GMS has the "stock" muffler and not the "tuned" muffler.

Comments:
1. The Magnum .52 was the fastest as I expected, but it was not that much faster.
2. The OS .46AX did very well for a new engine with the smallest muffler.
3. The GMS did much worst than I had expected. All the raves about the GMS must be due to the "tuned" muffler.
4. The Tower is old and low on compression and did the worst , but it had the "tuned" muffler.

The first photo shows the OS on my test bench.
The next 2 photos show the 4 mufflers.
In the rear view, the fat muffler on the end is the Tower, so-called, tuned muffler. This same muffler comes on some GMS .47 engines. It added several hunderd rpm when I tried it on the OS with a 10-6 prop.
The muffler on the left with the torpedo fins near the exit is the new OS AX muffler.
Next to the OS is the GMS standard muffler.
The muffler with the short extension in the middle is the Magnum muffler.

Muffler comments:
1. The Tower muffler has a much larger volume than the others.
2. The OS muffler is the quietest and appears to be the smallest, but is did very well in the rpm test.
3. Without the extension, the Magnum muffler would be tiny.

A final note: I have ordered 2 more Tower "tuned" mufflers. I will run the test again with all 4 engines equipped with the Tower.

Attachments
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_____________________________

Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
R/C Report Magazine, Fun Aerobatics Column
       Post #: 1

RE: OS AX-GMS-Magnum-Tower - 12/30/2003 6:49:53 PM   
Spaceclam



Posts: 4640
Joined: 4/13/2003
From: chatsworth, CA, USA
Status: offline 		had the os engine been run for 24 minutes longer like the magnum it probably would have topped the list.

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RE: OS AX-GMS-Magnum-Tower - 12/30/2003 10:56:49 PM   
Ernie Misner


 

Posts: 3146
Joined: 7/5/2002
From: Tacoma, WA, USA
Status: offline 		Great testing work Ed!!!

On my magnum 52XLS muffler, I drilled out the holes in the muffler baffle a couple of drill sizes and drilled out the muffler exit hole a couple of sizes. Since I do not have a tach I cannot say how much this improved it.

Ed, if you make these mods please let me know...:-)

Ernie

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       Post #: 3

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 4:25:46 AM   
Volfy



Posts: 3227
Joined: 1/4/2002
From: Houston, TX, USA
Status: offline 		Nice work, Ed. Now a simple Power/Cost comparison should put things in much better perspective.

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       Post #: 4

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 6:00:25 AM   
Spaceclam



Posts: 4640
Joined: 4/13/2003
From: chatsworth, CA, USA
Status: offline 		it isn't just power you guys! you should also take into affect the break in period, reliability, ease of tuning, and weight.

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Duct tape is like the force. It has a light side, a Dark side, and it holds the universe together.

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       Post #: 5

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 6:51:59 AM   
ZM2000


 

Posts: 171
Joined: 6/23/2003
From: Karachi, PAKISTAN
Status: offline 		Excellent work by Ed.

As I said before, regarding superior metallurgy, who has done the lab test? I found the answer.

One of my friend being a mechanical engineer took the OS and Mangum engines to an aerospace engineering lab and reports that:

a) The process of moulding Magnum is ordinary while OS goes through some superior electrical method (I am awaiting elaboration on this).

b) The microspopic analysis of cylinder liner and piston reveals that the surface of OS is much finer than Magnum.

So it appears that OS is better in metallurgy.

-ZM

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       Post #: 6

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 7:16:36 AM   
seanychen



Posts: 2914
Joined: 7/20/2002
From: Canton, MI, USA
Status: offline 		When I put the Tower muffler on my Magnum 52 XLS, the max rpm for 12.25x3.75 jumped from 12800 to 13700.

I love to see what the OS AX does w/ the Tower muffler. In fact, the tower muffler should fit all 4 engines in your test. Would you care to do a run on all 4 engines using the same Tower muffler? It would indicate the engine power comparison apart from the exhaust type.

(in reply to ZM2000)
       Post #: 7

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 8:30:06 AM   
old bird


 

Posts: 176
Joined: 11/23/2003
From: Reno, NV, USA
Status: offline 		Ed Moorman, that is very good information. Just the kind of research that means something real to the hobby. Thanks, and thanks for the info on the Saito .72 break-in. We have a couple of .46 FX engines and they have been good to us, plenty of power for our trainers and easy to start and tune. That stuff means a lot to beginners.

Regards from old bird.

(in reply to seanychen)
       Post #: 8

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 3:03:27 PM   
Ed_Moorman



Posts: 3673
Joined: 1/5/2002
From: Shalimar, FL, USA
Status: offline 		I have 3 Tower mufflers on order. The problem with them is the very fine threads on the muffler bolts combined with the soft aluminum of the muffler strip out. I end up re-tapping them with 6-32, but they finally strip, too. I always use Lock-tite.

I plan to run the test again with the Tower muffler on all engines. I am also going to try to test a TT .46 and an OS FX that a buddy owns. My TT .46 is in another buddy's scale plane with a custom muffler on it. He builds, I fly, so I loan him a lot of engines.

Here is an interesting thing about the OS AX. In their instructions, they recommend you disassemble the muffler and put it back together with hi-temp silicone to prevent oil oozing out the center joint.

_____________________________

Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
R/C Report Magazine, Fun Aerobatics Column

(in reply to old bird)
       Post #: 9

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 5:58:43 PM   
rcglert



Posts: 170
Joined: 1/9/2003
From: Mesquite, TX, USA
Status: offline 		In regard to the superior mettelurgy of the OS engine versus the Magnum......performance is what counts. OS and Magnum are both very good performers. Although the Magnum will give you much more bang for the buck, some folks feel comforted by the OS name and a feeling of lightness in the hip pocket area where their now empty wallet resides after buying an OS engine.

LOL,

Tom

(in reply to Ed_Moorman)
       Post #: 10

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 6:59:36 PM   
Spaceclam



Posts: 4640
Joined: 4/13/2003
From: chatsworth, CA, USA
Status: offline 		keep in mind. the better metalurgy means a quicker break in period. it also means it won't be so finigy during the break in period, and sure a more consistant outcome.

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RE: OS AX-GMS-Magnum-Tower - 12/31/2003 9:44:13 PM   
Ed_Moorman



Posts: 3673
Joined: 1/5/2002
From: Shalimar, FL, USA
Status: offline 		Before I go to the second of my test runs, let me say something about metallurgy.

First, In all my years since 1950, I have never heard any model engine expert, not an engineer in another area, and I am an engineer myself, say that nickel plating was better than hard chrome plating. The racing engine manufacturers, Nelson and Jett, use hard chrome plating. The electroless (meaning cheap) nickel plating is not as hard, as I recall. OS did have a large problem with it peeling on SF series engines and the early years of the FXes. To their credit, they did work out a solution. This was covered in full page ads touting a new process without mentioning it was a fix for a fatal problem. As I understand, the use a copper plating first, then the nickel. This is their "Advanced Bi-metallic Liner" they now advertise.

As for casting, if the parts fit in it correctly, the quality of the casting, and the finish, has nothing to do with power output. To be sure, OS engines have great castings and great finish. Personally, they can save the polish and cut the price $20.

For my part, I have never had a problem with any engine I have owned, and I have owned many. All were flyable and reliable. I just did not like paying the price for the present OS engines although I have owned several in the past. I take one of those back. The OS .91FX I own was junk until I put a K&B remote needle on it, but we are talking about .46 sizes.

I do break all my engines in the same, on the bench. I find I can control the conditions better, giving the engine short, fast runs on a slightly smaller prop with cooling in between.

_____________________________

Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
R/C Report Magazine, Fun Aerobatics Column

(in reply to Spaceclam)
       Post #: 12

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 9:59:03 PM   
Ed_Moorman



Posts: 3673
Joined: 1/5/2002
From: Shalimar, FL, USA
Status: offline 		CONTINUATION OF TEST

Courtesy of by buddy, Ugo Ferrari, I have added an OS .46FX and a Thunder Tiger .46 Pro. Both of these engines have been well run and are probably in the category of my old Tower .46, near the end of their time. I say this after running them. They were not up to the level of the 3 new engines.

Temp: 60 deg.
Humidity: Low
Fuel: Omega 10% castor blend
Prop: APC 12.25-3.75

Just to be sure 1 day didn't make a difference, I re-ran the OS .46AX, the engine we are comparing to with the same prop.

OS .46AX Stock (P-BOX) muffler 12,500 (100 rpm higher than yesterday)

OS .46FX Stock muffler 11,400

Thunder Tiger .46Pro 11,500

I am glad I re-ran the AX so I can say the change in weather did not cause lower rpms. In fact the AX was a steady 100 rpm faster.

As you can see these engines are probably not representative of the same engine that is new. A thousand rpm down is a bunch, but they were all I had available.

ONE FINAL TEST: I got out the Tower muffler, the one I have with the stripped thread for the rear bolt and tried it on the OS .46AX.

OS .46AX Tower "tuned" muffler 13,100

Is 600 rpm worth $15? I think so and, as I said, I have 3 on order.

My final thoughts. You guys who like OS better save your pennies, sell your FX and grab one of these. The .46AX, at least the one I have looks like a killer engine in the sport .46 class.

< Message edited by Ed_Moorman -- 12/31/2003 5:02:36 PM >

_____________________________

Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
R/C Report Magazine, Fun Aerobatics Column

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       Post #: 13

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 10:22:13 PM   
JNorton



Posts: 3133
Joined: 1/29/2002
From: Montague, MI, USA
Status: offline 		Ed,
Thank you for posting your results. I realize that it is not all inclusive, however it does point out some very good alternatives to O.S. It also shows that O.S. can still design a very good engine. Although I still don't like the idea of a 4 bolt head!
John

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       Post #: 14

RE: OS AX-GMS-Magnum-Tower - 12/31/2003 10:24:35 PM   
Spaceclam



Posts: 4640
Joined: 4/13/2003
From: chatsworth, CA, USA
Status: offline