O.S. .25la vs Fox .35

[Jim Roselle]

I am thinking about moving up from 1/2a models and building a Brodak Magician. The plane calls for a .25 to .35 engine. What would the advantages/disadvantages be of the O.S.25 vs the Fox .35 be?

Thank you,
Jim

[Phil Krankowski]

The Fox is less expensive (just over $50 after trade), lapped iron, good engine using old technology.  Requires very high castor fuel.

The OS is ABN, Aluminum piston, Nickle plated Brass cylinder.  It is new technology, requires more readily available fuels.

Phil

[James D. Hayes]

Fox .35 is cheaper and requires high castor oil. It also likes to vibrate. The OS 25LA will run on fuels you can buy at your local hobby shop. Depends upon your preferences. Old school plane, Old school engine? I'd probably go with the fox.

Jim Hayes
AMA 988835

[Andrew Saunders]

I have both of thise engines. I really like the LA .25 over the fox .35. Id recommend the LA .25

[Jim Roselle]

Thanks for the input, I like the idea of locally available fuel. How does the power output compare?

Jim

[Dennis Moritz]

LA25. Excellent no fuss no muss engine. An LA25 should start up and run fine, right out of the box, little or no break in. Personally I prefer the run. Stays in a 2 stroke. It's possible to adjust the engine to switch from a 2 stroke on the rich side, to a leaner 2 stroke. Worry about that later. Fox quality control so so. If piston fit is too tight or front bearing off center or too loose or the lugs not true or... issues, problems. Fox lovers know the drill. They have mastered the relic of 1949. The Fox break is difficult to tune for an optimum stunt effect. I have seen Noblers and the like mush around too slow then break into often talked about Fox break. You get a bit of a boost. Sure. But as far as I can tell most folks do way better with the comparative constant power of LA25s. I usually swap in an FP through the venturi needle. I don't like the 90 degree bend in the remote needle. Easier to get a speck of something in there. Harder to flush when there's a block.

[Dave_Trible]

Thought I'd throw out something to be ignored.  There seems to be an LA or Fox rut in the road.  Why not a good Enya?  They have a great ss.30 motor that I'm sure has at least Fox .35 power.  There are many older but great Enya .29s, .30s, and .35s on EBay.  For that matter I just bought 3 new K&B Stallion .35s,  4 green head Torps, several McCoys , etc.  off the bay at about half the cost of a new O.S. each.  This gets you a good runner at a fair price and helps keep a few of these treasures out of a landfill.  I just keep hearing the broken record LA/Fox/LA/Fox and there sure are other (better) options.  Just my thoughts...

Dave

BTW. Don't be afraid to buy an R/C motor in good shape. It's not too hard to make it C/L.  Jim Lee and others can make you a Venturi for it and Brodak has needle valve/spray bar assemblies.  Converting 6 or 7 myself right now from Enya .15s to a Veco .45.

[Steve Thomas]

Hear, hear, Dave. That SS30 is a great engine - hardly weighs any more than a Fox, but quite a bit more powerful. Mine runs so consistently it might as well be a good electric setup (except it sounds and smells better).  Can't even remember the last time I had to adjust the needle.

[Duke.Johnson]

I have the Enya .25SS, OS .25 FP, OS .25LA, and the Fox .35.  And would recommend them in that order. The LA is a lesser engine in my opinion.  The SS and the FP's are solid engines and start the first flip.  But then I also don't have to worry about the fuel for the Fox, my hobby store stocks it for us.

[Brett Buck]

I am thinking about moving up from 1/2a models and building a Brodak Magician. The plane calls for a .25 to .35 engine. What would the advantages/disadvantages be of the O.S.25 vs the Fox .35 be?

   The 25LA is no comparison, it's better in every regard - power, reliability, run characteristics. A Fox will require at least some modifications to work reliably on a profile, and to keep from severe vibration damage, require maybe $150 more aftermarket parts. IT also takes special fuel, and extensive break-in. All you need to do to a 25LA is bolt it on and go, use any fuel you can find.

     I just got done putting in a 539 point flight with a 25LA/Sig Skyray 35 in a 12 mph wind with nearly no practice and relative ease. I know from experience that the same airplane with a Fox 35 (with most of the tricks I know) is only marginally capable of getting through a pattern at all in similar conditions, even for me.

   This same, er, discussion comes up about every week or so, so plenty of past posts to read. It's an utter and complete no-brainer, not even a close call.

    Brett

[Dennis Moritz]

The new Enyas I've seen run over the last couple of years were more troublesome than LA25s. Often the Enyas seem down on power next to the OS engines. I believe the new Enyas are mostly cast iron piston/steel liner engines. Or ringed. Which means they usually need some break in if cast iron piston. (I steer away from ringed engines, generally, do not like the prospect of fitting rings and so forth.) In my experience these piston/cylinder types have liabilities when compared to ABN, ABC, or AAC. Over lean runs are more likely to damage cast iron/steel piston fits. Ringed engines can get fried for many reasons. The LA engines are built to a price. For instance, I have read the cranks are cast steel not forged steel. But the piston cylinders are ABN. A big plus. And the internal machining must be good (enough).The Enyas give the visual impression of better quality. They may in fact be a higher quality product. But, nevertheless, the OS LA Engines seem to be more reliable and easier to set up.

[Paul Smith]

You can buy ONE LA25 and it will work.

You can buy FOUR Fox 35 Stunts and ONE might work if you're lucky.

[ChrisSarnowski]

The LA25 certainly is a nice runner. Typically I replace the remote needle valve and plastic backplate with a metal one (thunder tiger gp25 backplate). A no brainer. Quiet as a mouse, too, with the stock muffler.

The Fox 35 is beloved by many folks. I have a few older Fox 35's, they run fine. Use correct fuel and you will be ok. Older engines better than new ones?

I haven't run in my Enya SS30 yet. I see positive reviews on it. Ready to go right out of the box, no plastic backplate or remote needle. I have some older ringed Enya 45's and a modern SS50 (ringed). Both run like champs.

-Chris

[EddyR]

In a moment of weakness I took a old profile with a Fox 35 on it to the field yesterday. The vibration could be seen in the flying lines. I flew it one time and put it away. A Fox works good in a nobler type plane but on a profile it is a wast of time. All the motors mentioned above will be much better. I would not put even a free Fox on that plane.
Ed

[john e. holliday]

If you are talking the Original Magician by Brodak I say  go with the .25.   After my first round attempt in Topeka this last weekend I proceeded to remove the Brodak .25 and replace it with my LA .25.   Was a great move I thought as I got thru the whole pattern with plenty of power.   Prop was an APC 10-4.   Yes, I am a Fox man but it is too much engine for the Original Magician.

[ChrisSarnowski]

Discussion of power for your Magician.

http://stunthanger.com/smf/index.php?topic=18469.0

[Bill Little]

I have found the LA .46 and LA .25 easy to use, with enough power to do the job on correctly sized models.  The old Fox .35 can be a lot of "fun" to use at times, but unless you have a large field of knowledge about the Fox .35 it can be a hassle.

Of the two engines you stated, go with the LA .25.  I can't say much about the Enyas, all the ones I have are 40 years old or older.  Great engines in their own right.

BIG Bear
RNMM/AMM

[Andrew Saunders]

I took my LA .25 and replaced the tubing between the remote needle valve and the venturi with a piece of 1/2 a fuel tubing and it runs great. Plenty of power and runs steady with no problems.

[Chris Wilson]

Like everybody else I intend to use my Fox 35 as a comparator, how else does one know how much better a modern engine is unless they do?

[Steve Hines]

I don't know how well you fly, but we used a fox 35 to get Samantha to get thru the hole pattern. I tried the other setups and they did not work for her. she need the break on the down side of loops and things. I think that the best motor for this plane would be the Brodak 40. This motor is light and it has more power than any of the other motors talked about. Samantha won the nats with this motor and just won FCM this weekend in intermediate, and was above 3 scores in adv. Everyone was asking what motor she was running at the nats, and no one had a better engine run any class. The setup that I use is 10% at 22% half and half, a os #8 plug and a 11/4 Brodak wood prop. The plug is what makes this motor run so good. Samantha has a Rojet 40 that I could not get a good run on thru the hole fight, used a #8 problem solved. Know you have a lot to think about, have fun.

Steve

[Andrew Hathaway]

It's no more fair to compare a Fox 35 to a LA 25 than it is to compare any other technology from 1949 to a current competitor.  The Fox is a great reproduction of a vintage engine, and it'll run just as good now as it ever used to.  It just happens that technology has moved on, and the LA starts easier, runs smoother, and makes more power.  It doesn't exude the classic vintage experience like the Fox but if you care more about raw performance than the total experience, you'll probably be happier with the OS.  Flying a Fox on a vintage model is an experience that can't be matched by a modern engine, just like driving a classic car has it's advantages over driving a modern car.

Is the Ohlsson and Rice one of the better ones too?

Take nearly every bad thing you've ever heard about a Fox 35 and multiply by a factor of 10.  The O&R was popular before the Fox came out, and the Fox 35 is a better engine in almost every way over the O&R.  The O&R .23s start easily, run well, and don't weigh anything, but they don't make any power.  The .29 and .33 make a little more power, but they shake worse than a Fox.  I hear the .60 makes good power but shakes too.  They're not built very strong, the castings and internals are delicate.  The head and cylinder on O&R engines are welded and staked, so if you do have a leak they can't be fixed at home.  They were originally spark ignition engines, and when converted to glow they can self destruct.  All that said, they sorta work for a fun engine.   

[Dave_Trible]

I'll put my O&R .29 up against the Fox!  Just kidding..... But they are pretty close.  Actually my ignition Forster  might give it a run for the money.

Dave

[Martin Quartim]

I also suggest you to check out the Enya SS30 S. With muffler it is lighter then OS 25LA, and in my opinion the Enya is a LOT more engine.  Mine I broke in 1h on the bench and it was good to go.

Martin

[Chris Wilson]

I also suggest you to check out the Enya SS30 S. With muffler it is lighter then OS 25LA, and in my opinion the Enya is a LOT more engine.  Mine I broke in 1h on the bench and it was good to go.

Martin

Hey Martin,
                   I have twp Enya SS 30's are both have iron pistons and I am pretty sure steel liners and even the RC version of the LA 25 is lighter than the current CL SS 30 - so I am not sure if you have a different version of the SS here?

(The Enya SS 40 follows the same route.)

Thanks.

[Michael Boucher]

What fuel and props are folks using in the O.S. 25 LA? Thanks 

[Duke.Johnson]

APC 9 X 4 on powermaster 10/22

[Brett Buck]

What fuel and props are folks using in the O.S. 25 LA? Thanks 

   There are about a million threads on this topic (some with more information), but I suggest this based on testing this last weekend:

   BONE STOCK CURRENT MODEL os25la-S RN, with STOCK muffler, no changes whatsoever from what comes in the box
   STOCK OS Glow Plug
   Powermaster 10/18 RC Sport Fuel (works with Powermaster RO-JETT 10%, too, and probably many other 10% fuels)
   Sullivan SS-4 tank, on suction, with muffler pressure
   APC 9-4 Prop
   Launch Revs 13600-13800. If too lean, One click richer on next flight, if it ever 4-strokes, one click leaner, regardless of RPM.

   I won't claim this as the best possible setup but I know for certain it works very well.

    Brett

[dirty dan]

Brett has it right so I won't argue. However I will quibble a bit...

In my view ya might want to be a little cautious with use of Powermaster 10/18 fuel. But only as in having a brew with a heavier oil load with which to compare.

Yes, my application is different (25FP, Mac's [aluminum] pipe, 10-3 APC prop, all powering a 500-inch scaled Impact built to profile configuration) but with 10/18 fuel the motor would tend to grab another gear during pattern, generally in square 8s. While this was hardly a deal-killer - Brett once flew the model with described setup and results and still liked the overall package - it was mildly annoying. And eliminated entirely by switching to Powermaster 10/22 fuel.

Again, back-to-back tests, along with paying close attention to the run will get you real close real quick.

Other fuels known to work for me are PM 20/20 tarted up with nitro and oil to net 25/22 or 25/20. Or one can just use straight PM 20/20.

Preceding sorts of fuel should not be required for a great many profiles. My setup is marginally better with more grunt, but it's also pretty damn decent on 10% fuel.

Dan

[Brett Buck]

Yes, my application is different (25FP, Mac's [aluminum] pipe, 10-3 APC prop, all powering a 500-inch scaled Impact built to profile configuration) but with 10/18 fuel the motor would tend to grab another gear during pattern, generally in square 8s.

  That's interesting. I notice something similar on Real Stunt Engines(tm), too. The 10/18 tends to have significantly more boost/brake in the corner than RO-Jett or GMA. On the case of the Jett it was not too subtle, it was like I had changed the venturi and pipe length by a noticeable amount. Much much steadier on RO-Jett than 10/18, more pull in the middle of the corner. The Jett will not run reliably on GMA, but when it was running, it was somewhere in-between, as was the Randy magic mix of SIG Champion and SIG Syn-Power.  Straight Syn-Power is a lot like 10/18 Powermaster. It's a trimming tool at this point.

   I had the "go to full tilt boogie around the square 8" sometimes with the 20FP, but that went away completely when I went off of uniflow with pressure. Uniflow with no pressure was fine, and suction with muffler pressure was fine.

   I am not sure what the mechanism is, although I strongly suspect that a big fraction of it is oil drag increasing the load on the engine so that the maneuvering makes less of a difference. Oil and bearing drag is a HUGE factor in how the engines run. Some of the best 4-2 breaks I have ever heard were from my hero PTG's McCoy 40s that were set up for "zero break-in" for some WC in the early 60's. The shafts were insanely loose, like 1/8" or more movement at the prop tips, they spewed oil like it was going out of style, but they ran perfectly. You can't say there's a lot parasitic drag on that. The Retro 60 is very similar, through BDC it's remarkably free (although not sloppy since it has ball bearings).

  David found the same thing on the PA75, it runs much smoother with 10% RO-Jett, although the others were acceptable, too.

    Brett

[Martin Quartim]

Hey Martin,
                   I have twp Enya SS 30's are both have iron pistons and I am pretty sure steel liners and even the RC version of the LA 25 is lighter than the current CL SS 30 - so I am not sure if you have a different version of the SS here?

(The Enya SS 40 follows the same route.)

Thanks.

Hi Chris,

I have the same Enya SS30 Iron piston you have.  Withtout the muffler the OS 25LA is just a bit lighter, but when you add the stock muffler then the Enya SS30 end up lighter because it has a much lighter muffler. Can't remember exactly, but the TOTAL weight difference was around 20g.

Martin

[dave siegler]

Comparing a fox 35 to an OS 25, is like comparing a Honda gold wing to a old Harley ( from the 80's)

The gold wing is smoother, quieter, shakes less, requires less maintenance.  In most measures on paper it is way a better machine.

But people love the Harley anyway and spend tons of money on aftermarket pats. The Harley sounds different.

Both will get you there.

That being said there was over 100000 fox 35's ripping up the streets of Milwaukee this weekend. 

Oh I have 5 airplanes with OS engines on them and one fox 35 on a bi slob.  Love my fox for its limited application.
I am a Honda kind of guy. 

[dirty dan]

   I am not sure what the mechanism is, although I strongly suspect that a big fraction of it is oil drag increasing the load on the engine so that the maneuvering makes less of a difference. Oil and bearing drag is a HUGE factor in how the engines run.    Brett

Too bad this is being tucked into a Fox 35/25LA discussion but I agree with Brett's primary point, including that none of us are really sure what is happening here. On the other hand I recently read a fabulous book, Kevin Cameron's "Classic Motorcycle Race Engines" which was released only a few months ago. In the strongest possible terms I would like to suggest anyone with interest in four- or two-stroke engines buy a copy and enjoy it. Cameron has a splendid way of making the complex seem, while not simple, very understandable. Kinda like Brett also has that ability, come to think of it...

Back in the day of Castrol R in healthy doses there was a lot of attention paid to drag created by spinning parts real fast in a mist of pre-mix. This attention didn't ease much when advanced synthetics allowed designers to specify much-reduced percentages of oil in the fuel. We are kinda dinosaurs here; even chainsaws and motorcross bikes use a mere 2% oil in the fuel.

It would really be interesting to build a solid, no-nonsense model, a SIG Skyray being my choice for a number of reasons. Power it with a stock 25LA. They run so well in a CL Stunt application that any weirdness whatsoever is real easy to spot. And they are consistent, reliable, and cheap.

Go fly. Once the motor has settled in a bit settle on a baseline fuel and I see nothing wrong with PowerMaster 10/18 or 10/22 or 20/20. SIG Champion 10% would be quite good.

Now line up a bunch of different blends of fuel, the only caution being to strive for consistency in these fuels. (Certainly no on-site mixing in small quantities!) You might be pleasantly surprised to see the effectiveness of back-to-back-to-back flights when closely analyzing run qualities, especially when variables other than fuel have pretty much been eliminated.

This would seem to be a worthwhile series of tests with the bonus being that even if not all the data were transferable to "real" Stunt engines (I had to force myself to write that!) much of it would be useful in all of our engines.

Dan


 

[Steve Helmick]

It's been awhile since we could get Powermaster, and even longer since we could occasionally get the RO-Jett mix. Do I remember rightly that it's 15% synthetic and 3% castor?

That's pretty close to Wildcat 10-18 Premium, with 20% of the 18% being castor. I sometimes remember to add an ounce of Randy Aero's "Aero-1", aka "Snake Oil". It's really thick when cold, but flows ok during the warm weather months (i.e., mid-July to mid-August). I remembered recently, but was hoping that it would decrease my run time a little, mostly.

Get the .25LA, upgrade the backplate and NV, and enjoy it.  Steve 

[Brett Buck]

It's been awhile since we could get Powermaster, and even longer since we could occasionally get the RO-Jett mix. Do I remember rightly that it's 15% synthetic and 3% castor?

   Why can't you get Powermaster?

   The RO-Jett mixture is reportedly 15/7 synthetic/castor.

   Brett

[Steve Helmick]

Our (Auburn) LHS went Tango Utah a year ago, Memorial Day weekend. The closest LHS (Covington)  is basically an R/C car shop, they're still in training as to what we need in the way of fuel, and they're at least 35 minutes away. Usually, it's just easier to go to Hobby Town (NOT the chain) in Parkland, 50+ minutes away. And they carry Wildcat. If they carried the Wildcat "Jet 10%" (for ducted fans), it would be even better. Might see about getting them to order a case of it, but without having any to test first...nah. Pete and I like the Wildcat alright. About everybody else has gone 'lectric.    Steve

[Brett Buck]

The new Aeromodeller has jumped on the bandwagon, as well. Sort of. They even refer to The Dirt!

   I may write a letter to the editor on this one, they are talking about using a 9-6!

   Brett

[dirty dan]

The new Aeromodeller has jumped on the bandwagon, as well. Sort of. They even refer to The Dirt!

   I may write a letter to the editor on this one, they are talking about using a 9-6!

   Brett

Don't recall exactly what I did to @#$% off the Brit modelling press, but it would seem not all of them have forgotten it!

Uh, they don't cite me as the source of suggestion to use a 9-6 prop do they?

I have always used stuff like this to calibrate users of the 20FP in particular, small-bore motors in general. If they go all giggly over use of a totally inappropriate prop such as a 9-6 they really ought cut to the chase, telling one and all they are totally clueless.

Dan
 

[Brett Buck]

Don't recall exactly what I did to @#$% off the Brit modelling press, but it would seem not all of them have forgotten it!

Uh, they don't cite me as the source of suggestion to use a 9-6 prop do they?

  No.

   Brett

[Mike Scholtes]

Rest easy; the article several times says the APC 9-4 is the prop of choice on either the FP20 or 25, though the author has used other props including a 9-6. Sounds like his experience is the same as ours.

[Dan McEntee]

  Are you guys reading the on line version? I finally found a news stand near me that carried it, but it is usually pretty late. Might have to pony up for a subscription.
   Type at you later,
   Dan McEntee

[Brett Buck]

  Are you guys reading the on line version?

   Yes, I got one copy just to see it. It seems a creditable effort but I get the distinct impression that it is very much a one- or two-man operation now. Not that this is a bad thing, but it doesn't look or feel much like the old AM.

    Brett

[Steve Scott]

I just found myself in this same dilemma as I'm currently building a Brodak S-1 Ringmaster kit in order to participate in the upcoming October event.  I have a drawer full of Fox 35s and several FP 20s.  I consider it a bit sacrilegious to put anything other than a Fox 35 on a Ringmaster but no one locally carries Sig 25% castor any more.

I've used the LA 46 with good results and was anxious to try the LA 25 this time around.  Found one in a LHS and asked the clerk if I could look at it.  It was the LA-S control line version, brand new but the old blue color.  Didn't have a price tag on it so he asked me if I knew what they went for.  I played dumb (Tower has them for $80) so when he suggested maybe $40 I really tried my best to keep my poker face.

I walked out with a brand-new LA-S 25 for $39.  I'll fly it stock but do have spare metal backplates and OS NVA.  Add a dash of castor to my RC fuel and I should be set.

[Dennis Moritz]

Great deal.

[john e. holliday]

And he was probably glad to get it out of his road.   The talk of the Fox .35 Stunt being the engine for the Ringmaster have forgotten a couple of others that were competitive/flying back in the day.  Mine first one had the K&B Greenhead .35.   I remember some with the early Johnson .35.   And one in particular that had a wore out O&R of some size on it.  The young man was one of the special kids at the time.   A slow learner and kept to his self most times.   I would help him launch his plane if I promised not to touch the needle.  He had no trouble starting the old O&R.   It would take off fly a few laps and then slow down an roll/taxi around the circle a lap or two and be up again for a few laps.   Never seen him do loops or invert, but he was having fun.   Then I moved and never saw him again.   After coming back to the city I was in Charly's  Hobby Shop and he said a fellow flier had just left that I probably should remember,  to this day I can't recall his name.   It was the same kid that some how started to learn and became a business man.   Well to do with a limosine to ride in.  If only I had kept a ledger of all my modeling experiences.    Maybe Randy C.  might remember him.

[Steve Hines]

Enya 30 does have more power than any 25 or fox 35 out there. just put a new Sporthawk  with the Enya 30 on it, set it up like a 20 fp. Was using a mac muffler on it, the thing would turn a 11-4 brodak wide blade with power to spare. Had to go back to the enya muffler to tame it down a little. This runs just like the 20fp but with 2 time the power. This is only 530 sq and weights 35oz, I think I will try it on a Nobler arf.

Steve