I was figuring that I'd use a .40 LA-S in my Nobler ARF when I get around to assembling it.  But I find myself with four FP-S .25 engines.  Looking through past posts in this section, there have been LA-S .25 Noblers that are said to fly well.  I also read that with the .40/46 LA-S, the plane gets nose heavy, so that's why I was wondering on the .25 FP-S.  Also, I was flying a gimme Flight Streak with a FP-S .25 engine this past weekend.  On 60' lines I was doing 3.5 second laps.  Much faster than my FS ARF with the .25 LA.  I did not find posts by anyone who had flown a Nobler ARF with the FP .25 engine.  Anyone have this experience?

In my opinion not enough engine unless you fly short lines and can keep under 40 ounces.

I agree that an OS 25 FP is really too small for a Nobler ARF. It might pull it around OK in level flight, but struggle in maneuvers or if it is a bit windy.

I have a Nobler ARF. I had an OS 40 LA on it and needed a bunch of tail lead to CG balance. It weighed close to 49 oz and did not fly well.

I came across and picked up the new Enya SS 35 EX BB ABC engine and put it on my Nobler. Wow, what a difference. The Enya SS 35 is designed around a 25-size case and is quite light at 7 oz. A Fox 35, which the Nobler was designed around once upon a time, weighs 6 oz. With this lighter 35 engine (compared to the 40 LA) I was able to remove most of the tail lead. Model overall weight came down to 43 oz all in (w/ stock Enya muffler). The model flies totally different at 43 oz.

I used a 25 LA in Nobler ARF and it flew nicely. 62' x .012 lines and 10x3 APC prop. 10% nitro. Full disclosure, it wasn't a powerhouse and if it was really windy, it was better to leave in the car.

Back when I was flying glow, the secret sauce to a competition Nobler ARF( besides enhancements like tip weight box, adjustable leadouts, equal flaps, upgraded elevator and flap controls and a few more) was the OS LA 46 with the  OS venturi restrictor, Shipp backplate, Smith venturi needle valve/body, ports tipped(although not a must) and a tongue muffler.  The stock muffler is where most of the weight is. An APC 11-4. Not at all nose heavy even with 4.5 ounce tank.  Of course, we replumbed the tank internally and for external air pressure. That combo could fly in sensible wind and grunt aplenty for verticals and overheads .

Quote from: Clint Ormosen on October 03, 2025, 10:59:55 PM
I used a 25 LA in Nobler ARF and it flew nicely. 62' x .012 lines and 10x3 APC prop. 10% nitro. Full disclosure, it wasn't a powerhouse and if it was really windy, it was better to leave in the car.

   I never tried one in a Nobler ARF but I had a similar experience with the ARF Primary Force. Started out with an LA.25 as per instructions and everything set up like the book. It flew right off the bench, but at best was marginal on power. Not a very big model, but weighed in the 43 ounce range, maybe 45 I think when new. After a season, I decided to try the FP-.25 and get some experience with that. It was better, and I'm convinced the FP.25 is stronger than the LA.25, but like you said, it was in any kind of wind where you really had to be careful in overheads and such. One of these days I'll try an FP.25 in something else that may be just a bit smaller and a bit lighter.
  Type at you later,
    Dan McEntee

I ran an OS .25FSR in a Noblarf for a while. The trick was to try to keep it below Mach 0.9 with the right prop. Too much fiddling with props and fuel for different days. Plenty of horsepower, just not as tractable as you might like if you are used to running an OS .46LA. The .25FSR even though an older engine probably has more grunt than the FP, which has in my opinion more grunt than the LA.

I have been happy with a good Brodak 40 in my Nobler ARF

Mark,
You need to setup the OS 25FP like they do for the OS 20FP per Brett Buck instructions. Use the stock 3030 muffler, stock NVA, stock full venturi, APC 9x4 prop, 10 - 15%N fuel. Set the CG at ~16% average chord,

With Brett's setup it will pull the Nobler better than a strong Fox35. Keep the lines to 0.012" cable and ~58' C to C.

Best,     DennisT

Maybe mine was light but I have flown mine happily with a 25FP.

60ft lines A 9x4 prop is too small for the 25FP.

I fly my 25FP with 10x3 APC and 10x4 Top Flite wood. Engine runs in a wet 2 solid as a rock for the complete pattern.

Don't underprop the 25FP with a 9x4 you don't get the power you need.

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