Daryl Martel

My Feedback: (3)

Getting a little bit more back on topic, the point I was trying to make is that Fox engines aren't exactly highly desired, which is why you don't hear much mention of 'em in comparisons such as this thread. To hold a Fox next to an O.S. engine is like night and day. It's like comparing an industrial farm implement to a genuine aircraft part! Rough industrial finish to an almost jewel like finish! Do Fox engines perform? Sometimes they do. Are they reliable? Sometimes they can be. With the advent of better metallurgy (forget the heavy Fox IRON pistons!), design, precision AND quality control processes from the competition, Fox engines really aren't keeping up with the times. Let's face it, since Duke Fox died, who is left to carry on R & D? They are at a dead end development wise and I doubt they'll ever come out with another modern, quality glow engine. Their gas engines can't be too hard to cobble together - basically a custon crankcase mated to off the shelf industrial parts. If people chose to buy and run Fox, good for them - nice to see not everyone is about minimum weight, maximum performance and appearance. There will always be a need for a basic sport engine. Considering that because of their low desirability Fox engines can often be bought used for a decent price, used Fox engines may actually offer good value! New I don't think they're good value at all! You compare a Fox to a Magnum for example, IMO the Magnum wins hands down too! Hobby People has the Magnum .46 on sale right now for $69.99 - how can you compete with that! Me, I get burned, I move on... My time and money are important to me and I'll stick with more quality brands. You people can defend your Fox engines all you want, to me personally they're no longer even in the same league. I will say this about the Fox company though - nice people offering excellent customer service. They are competing in a brutally competitive and challenging market. This Fox situation kind of reminds me of the motorcycle situation - some people drive Harleys (and we know what a loyal bunch they are!), some Ducatis, others Hondas and some BMWs. They all have a different feel and even though they all get you down the road, people are driving them with slightly different intent. Whatever floats your boat. Lets just have fun doing it!

Hobbsy

My Feedback: (102)

The Fox .50 is the lightest of all the .50s, even lighter than the Webra .50.

dikfor

let's see...51 replies...what was the original topic? hmm...something to do with an engine comparison? c'mon Ed, it's been 6 days since you started this beast- get testing. do it in the house if you have to. hey, i'll send you a TT .42 for the comparo. it's got 10 gallons through it and still hovers a 5lb plane. has bushings though, last time i checked...

Ed_Moorman

My Feedback: (1)

I did get in the Tower muflers I ordered, but the weather has been foggy and damp. I would rather wait for a change back to close to the same conditions I started with. Besides that, I had to go back to work. I'm an engineer during the day and I also teach college level math courses for a local university, Troy State in the evenings: 2 in-class and 1 on line this term. And I have a column due on the 15th. Keeps me busy. I know, it's no excuse for not running engines.

With regard to the MAN .61-size engine comparison test, the tester, Dave Gierke, tried various fuel and glow plug combinations until he found the best one for each engine. As I recall, he used a Thunderbolt plug and only 5% nitro fuel for the Fox .61 test. I also remember him saying that it didn't run well on higher nitro fuel, even 10%, and didn't run or idle well on a Fox plug! Most people would run their favorite plug and 10% or 15% fuel and get poor results. it to Dave's credit that he experimented with enough different combinations to find the best one for each engine.

The Tower .61 came in a close second and first in some categories. I think it'll run on anything. Makes me think the Tower .75 would be a good buy.

3d-aholic

My Feedback: (7)

I wonder if thats the problem with my Fox. I've been told over and over again, that these Fox motors were actually designed by Duke Fox to run on 0% Nitro. And when I ran this motor 28 years ago, I remember it running great...but it was in fact 0% Nitro...because I was breaking it in.

However....it severely hurts my brain to think an engine would run that much more reliably with 0% nitro compared to 15% nitro. And the reliability would have to undergo at least an order of magnitude of difference to be useful for anything and be reliable enough to suggest the plane would make it back around to land.

I have tested different plugs and that made little or no significant difference.

Tribum

I'm about to order an OS-46AX with a 11 x 6 prop for a Great Planes PT-40 MK II Trainer.

I would appreciate any input on prop choice and what % nitro to use given that I live at 7000ft.

Is there a given protocol for running the engine in? Should you use different fuel for running in? The OS FAQ assumes you already know what you are doing.

3d-aholic

My Feedback: (7)

I'm sure you will get a lot of suggestions...most telling you there is only one prop that will work.

Its a personal preference. An 11x6 will make the plane fly faster, an 11x7 is probably average, an 11x8 will make the plane fly slower. I have several OS 46's the previous incarnation or two...all 3 of these props will work and I have used all 3. The make is probably more important than the pitch/size.

An APC will make the plane fly faster and typically seems to have the least wasted energy. A MA prop will make the plane fly slower, have more survivability, and be the roughest sounding. A wooden prop will have the least survivability, probably be the lightest so run fairly close to the APC in RPM's and the one causing the least stress on your engine as far as changes with RPM.

So the question is what is do you think you would prefer? Most people don't know...so they get several props and thats probably what you should do as well....one is bound to break, or get chewed up sooner or later anyways. I would get an APC 11x6 for when you are comfortable with the plane and want to make it more thrilling a bit...and maybe a cheap MA 11x7, 11x8 for the first couple of flights.

Ed_Moorman

My Feedback: (1)

For a trainer, if you are just learning, you won't be instered in ultimate performance. Especially if you are on a paver runway, get yourself a few Master Airscrew 11-6s. You can scruf these up and still fly. They aren't as fragile as the tips on the APCs. There is no doubt that the APCs will give better speed, but you need a rubber prop until you learn how to land.

Use the same fuel for break-in as you plan to fly with. I would recommend a 10% castor blend like Omega, Power Master or Sig.

As for Fox engines, Duke went through a design phase where they were designed to run on 25% and then, when the price of nitro went up, designed for 0% FAI fuel. The rest of the world doesn't use nitro very much, you know. FAI type engines usually have a much higher compression ratio that makes them run hot with a lot of nitro. They probably had a different combustion chamber shape, too. You are fighting the problem if you want to use 15% in a Fox .61. The article recommended 5% and a Thunderbolt plug. Read the article, it is very interesting.

3d-aholic

My Feedback: (7)

I have a Fox 40 not a 61....but I have read the article you are referring to.

I kinda thought that Tower won in that article when you take into account, price, warranty and everything else.

What I really would like to know Ed, is why didn't you compare the Magnum 46....seems fairer.

Ed_Moorman

My Feedback: (1)

Hey, I'll test any engine someone gives me, but since I bought all these myself, I went with the .52. It was my second one so I thought enough of the first one to get the second. The GMS, I just wanted to try. Next, I got a small bonus so I bought the OS because it was like a free engine. Since I had 3 new engines, I decided to run my own test.

You also probably noticed I used a fun fly prop, which I run on many of my .46 size engines and did not try several different props. I was making a quick check one afternoon. I got the OS AX and decided to compare it to the others. Now, when I get some good weather, I'll try them with the Tower mufflers I just received.

The results tell me that my OS AX is a pretty strong engine. The Mag .52 is larger, so I expected it to run faster. The GMS was disappointing. Most of them originally came with the tuned muffler, which is identical to the Tower, and I feel its reputation for power came from the muffler. With the standard muffler, it was just over 12,000 rpm (12,100). I'll know more after I test all of them with the muffler. Maybe it gains a lot.

I would also have liked to test the Irvine .53, but they are really pricey and I have about the mid-sized engines I can use. But, if a free one comes in I do have a test bench.

Maybe someone else wants to try a new Mag .46, OS .46FX and a TT .46.

maxtenet

Good comparison , but who uses a 12 inch prop on a .46? Run a 10/6 APC and give us the results. It would be far more useful info!

Max

seanychen

My Feedback: (4)

I use a 12.25" prop on my .52. While 10x6 result would be more useful to perhaps a greater majority, there are at least 25% of people running this engine who fly 3D using 12" low pitch props.

CHOCOFAN

[sm=confused.gif] Hey ED get the same screw for the Tower Muffler,this time instead of using the same nut, use a lock nut instead and don't over tightin it.

Ed_Moorman

My Feedback: (1)

I was talking about the bolts that hold the muffler to the engine. I've never had any trouble with the long one down the middle. Of course, Lock-Tite, a lock nut and Zap-A-Dap-A-Goo on the outside help. The muffler was originally made from pretty soft aluminum and several of us in my club that bought Tower .46s when they first came out had the muffler strip. Most of us re-tapped them for a 6-32, but these also eventually stripped. I think the heat expansion of the engine and muffler aluminum are so much greater than the steel bolts that if causes the soft aluminum of the muffler to strip. Metric bolts also have fairly fine threads which don't have the deep bite of US threads.

Who uses a 10-6 on a .46? I think that is severely under propped. On a fun fly plane you'll want a 12-4 or 12.25-3.75 and that's what I fly most of the time.

Please don't confuse me with an official R/C Report engine comparison test. I write about aerobatic maneuvers and those are the type planes I fly. I happened to have several different, and fairly new engines so I ran my own little test and I found out what I wanted to know. I felt others who fly fun fly planes might also want to know the results and it seems to have generated some interest. I had no intention of ever running a 10-6, or any 10 inch prop, for testing.

Ed_Moorman

My Feedback: (1)

Here's the final installment of my mini comparison test-the runs with Tower mufflers

I ran the OS .46AX first because I had run it on a stripped out Tower I had and I wanted to make sure the results were comparable. They were the same.

Magnum .52XLS, Tower muffler 13,600 rpm
OS .46AX, Tower muffler 13,100
GMS .47, Tower mufler 12,400

I didn't run my old Tower .46 again because I had already run it with its Tower "tuned" muffler

The Magnum gained 800 rpm.
The OS gained a respectable 700 rpm.
The GMS gained only 300 rpm.

Conclusions:
1. Maybe mine is not a "good" GMS. I could hear the difference in prop noise when it ran. It was noticeable when the others revved up. But for whatever reason, my GMS .47 with either the stock or tuned muffler did not measure up to the Magnum or OS engine.
2. The Magnum .52 and OS .46 really hummed when I tuned them on the Tower muffler.
3. The Magnum is a bigger engine, but the same weight, so it should have done better. The OS AX was no slouch.
4. The Tower muffler added a good bit to the top end, well worth the $15 price tag, in my opinion. That's the reason I ordered 3 of them and now have them on all three engines. The stock mufflers are in the basket with the unused engines.

Now I can write my RC Report column, and hopefully include this test, and get ready for warmer weather-60 deg plus, please. I've got some seaplanes, some land planes, some fun fly planes to fly.

Daryl Martel

My Feedback: (3)

Nice job Ed. Anyone know how the Macs mini pipe one piece mufflers compare to the Tower mufflers? I've already got one on an Irvine .53 and have a 2nd on the way. I've seen a few threads about how opening the outlet on them improves things. My understanding is removing the baffle on most stock mufflers will improve things a few hundred RPM, at the expense of more noise of course. I see the pricey Ultrathrust mufflers have a real good reputation for adding RPM, similar to the infamous mousse can tuned pipe set up... I'm assuming the trick with the Tower mufflers is more volume, no baffle and perhaps a slightly larger outlet? Can anyone shed light on that? Jeez Ed, now that you're this far, if you want some really meaningful, real world comparison testing info that guys are dying to know, that would be it! Everyone looks to the engine comparisons by David Gierke (spell that right?) in MAN with great interest, and I've noticed they generate great debate here on the 'net... along with a little "I told you so", or "it must be correct, it was printed in the magasine" type of response. Comparing .46 engine RPM with maybe a sport prop like an APC 10 X 7, or 11 X 6, and various aftermarket muffler options would be very interesting. In the .5 class engines, heck, on my Irvine .53 I can even run a 12 X 6 comfortably. I'm assuming David Gierke (MAN) and Clarence Lee (RCM) get their engines sent to them free for testing - now that RC Report has really come into it's own, is that kind of thing not yet happening? It would be cool if you had more .46 engines and .50 class engines as well as more mufflers to play with, especially for free! Ed, I think a test like that would really put RC Report on the map!

Spaceclam

you should compare the os 50 ringed with the magnum 52 both with the tower muffler. there is a significant diference in displacement between .46 and .52. the os 50 ringed would be a better comparrison.

Ed_Moorman

My Feedback: (1)

Hey, I told you guys, I am not the R/C Report engine columnist, so I don't get any free engines sent to me, not that I'd turn one down. As for any other engines or other props, as I said, I buy what I want to fly and that's what I tested. Maybe someone else wants to buy a new OS .50, Irvine .53, Magnum .52 and OS .46AX and run their own test using 10-6 props. I'd like to see how they do, myself.

Several years ago I ran a little test at the field with the Mac's black muffler. I didn't gain anything on a Thunder Tiger .46. I tried a 60 sized one on a Thunder Tiger .61 and actually lost 500 rpm compared to the stock muffler so I have never used them again. I think I gave those 2 away.

Daryl Martel

My Feedback: (3)

Thanks for the feedback Ed. I really should subscribe to RC Report. Too bad they haven't gone web page yet. I think I'd be willing to pay for that. Re engine testing at RC Report, I had the impression in the thread you were involved, not just doing it for personal interest. Re the Macs muffler, I like them because they're light, clean looking and more aerodynamic. Actually lost RPM you say! Might have to play with opening the exhaust opening and compare... in the summer when it's nice outside again. Too cold to play outside now! Cheers