O.S. 46 SF - any good?

Thanks,
Tim

That OS Max model is (one of the ones) in between an FSR and the FX that is made today. There were never any complaints about the nickel peeling off any of the SF's that I know of, or from the FSR's (there've also been SX's and VF's along the way also, but not in every size). It has dual ball bearings and a relatively bulky case for its displacement compared to the 40's and 42's that have been sold with plain bushing shafts and adopted by the C-L fraternity.

(I suppose the one you are interested in is the one now bid up to only $41, eBay # 56092700? You can anticipate some bidding from RC folks, up to the $60-plus area, unless you get lucky.)

The 40-size FSR's and VF's certainly were and are used for stunt, with tuned pipe exhaust setups. (And those models were also relatively bulky/ heavy, even more than the SF's.) If those could be used that way, the SF surely would qualify for the same type use. BUT none of the O.S. Max engines made since the "H" models would perform in the Fox/ McCoy/ ST 46 stunt mode, the 4-2-4 breaking run, without rework.

Nevertheless, even without pipes and without rework, there are various C-L folks using very low pitch props to let the modern engines rev up into their version of a "rich" two-cycle, without running away badly in the air. In the far NW, the Mac's "One Piece Muffler" works for a number of the stunt types up there much like a tuned pipe.

When I had a couple of the larger, stock FP engines near the initial release date for those, the (local) availability of 11-3's and 12-3's at acceptable cost was practically nil, and the 40 would definitely run away with a 4" pitch prop in my tests. Now that Rev-Up props seem to be available again, at least by mail, maybe that low pitch prop expense situation is relieved.

You can always resell an SF 46 to an RC type modeller without much (if any) of a financial loss, if it turns out to be too big, too heavy, or too fast to suit you.

P. S. Added in Edit, 3-10-01: checking my estimate of what the auction price on the 46 SF might do, I found two FX 46's up for bids now also, one at $52 and the other at $61. The current SF 46 is up to $47. But a look at "Completed Auctions" shows that for some reason the FX's bring more than SF's. My own opinion about comparative values is the OTHER direction!

SF's have gone for $61 for one, and $62 for another, with a NOS one only getting $75! FX's, especially NIB, were substantially higher, for the most part, but one did sell for $46.

Kiwi

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Previously Edited on Mar-09-01 at 01:37 PM (EST)

K.

Currently building a Kestrel (not super kestrel) and look to try both uniflow metal tank and plastic. Then and maybe I could give first hand opinion other than this is the friendliest, smoothest running engine I've ever owned.

If there is a negative to this engine, I would say it is the weight....it is a bit heavy. Want to put it on an RSM Skylark but think I'll need significant tail weight. (One of those don't know until you try things..unless you're a math wiz!) Just bought another NIB from an online auction. Paid more than my wife likes, but should say that I like this engine.

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The Randy-worked 46SF is an excellent stunt motor for 4-2 break. It also works reasonably well with TP-style props. It's easily a match for the long-gone ST60, but is of much higher quality, and has none of the shake.

The stock motor with a slight muffler mod works extremely well with typical TP props of 3.25-4.0" pitch. A typical prop would be a Brian Eather 12-3.4 2-blade at a launch rpm of around 10800. That will generate a very reliable a 4-2 break, just at higher speed than you are used to.

Use the stock muffler, but take a prop reamer and ream the outlet hole out as much as possible without removing the exhuast outlet. The stock venturi and spraybar is pretty good, but be sure to seal the area where the 90degree fuel fitting meets that case, or it will be impossible to needle. Install it with the "closed" side towards the case. If you don't do this, what may happen is that the fuel in the fitting will get sucked in around the spraybar hole right into the case, and it can leak enough to still be too slow even with the needle all the way closed!

Nickel vs. chrome is irrelevant, it will last for more flights than any of use are going to fly.

>If there is a negative to
>this engine, I would say
>it is the weight....it is
>a bit heavy. Want
>to put it on an
>RSM Skylark but think I'll
>need significant tail weight.
>(One of those don't know
>until you try things..unless you're
>a math wiz!)

Yes, but it's probably less than the ST60 which it replaces. The Skylark is on the small side for this kind of power. This engine will easily fly all the 40-60 TP airplanes like the SV-11, Impact, etc. My occasional flying buddy Bill Howe had one on his 720 square inch, 65ish ounce Macchi 202/(Genesis) and it pulled it around very smartly