Hi all, I am getting back in the hobby after almost 20 years. When I stopped flying my Flagship airplane was a Whiplash Delta winged plane with the Jett 50 or 56 F.I.R.E engine (I don't remember exactly which size it has been so long) What a screamer!! The hobby has clearly changed since then.

A very nice gentleman in the club I joined practically gave me a nice looking OS 40FP and a newly recovered SIG LT40. The LT40 currently has an OS 46FX that he flew the plane with. I am thinking of using the 46FX on a 40 size Ultra Stick.

Any opinions of using the OS 40FP on the Sig LT40? Would this be a good combination for flying the LT40 with the OS 40FP? I don't want a sluggish trainer but I think I should consider myself a new pilot after all these years. I think what I am really asking is would this combination of the Sig LT40 and the OS 40FP be something you would consider good for a new pilot to learn on and be successful with?

The OS .40 LA is in fact a better engine in that model than the .46FX if you fly at sea level as I do here in Sweden!
Use an APC 11x5 might even be good with a 12x4.
Overpowering a trainer is no good!

The FP 40 motor is practically made for a 40 size trainer, they were never overly powerful, but they were real reliable with good fuel in a clean motor.

I was just looking at the Tower website and didn't see either a 40/46 FP or LA listed so, that being the case, I went to the OS webpage. What I found is that none of them are available.
You would have to go with the 46AX or, if that much power isn't really what's needed, there is the 35AX. The 35 takes a 10X6/7, 11X6 or 12X6, according to the instruction book while the 46 would use the 10.5X6, 11X6/8 or 12X6/7

The LT40 is very forgiving for a wide range of power choices. The 40FP will be excellent for the use on it. Sure, not the higher power output of the 46FX, but it doesn't need it at all, either. General performance will be about the same, although you may not have the same strong vertical abilities or top end speed. But its a trainer, and doesn't need those. Good plan to reserve the FX for later use on a plane that can better use it - the Ultra Stick.
Play a bit with prop sizes - you may be very surprised at how the LT40 performs using a 12x4. Top speed will be lower, but it will pull through almost anything extremely well - and allow you to slow down for landing even better.

I flew a number of my trainers and then a Goldberg Tiger with the .40FP. Its a plain bearing engine that is extremely reliable and is perfect for LT40.

I have one myself, I use it to hot rod a .25 size balsa wood model instead of spending a lot trying to find a 25FX-AX or .32 SF/AX. FP 40's are everywhere for around $40 these days.
It's a great engine for a trainer, helps the beginner think ahead of the plane, easy to tune, focus on flying more. Light weight, no ball bearings to rust out from neglect. Did I mention they're $40?

I bought a used ready to fly with a .40 back in the day. Under powered for me especially flying in high winds. That plane is closer to a 60 sized trainer. An os 55AX would be my choice nowadays. I built a kit one and threw a ST .61 on it. Flew great. . Then I threw a ST .90 on it that I needed to break in. Perfect little hot rod.
i can’t remember if I burned it on the burn pile back in the day when I took a hiatus. I gotta get out and look in the back garage.
I have a Saito 90 Twin that I just rebuilt and the old LT would be perfect to break it in.

Nice to see how a trainer can be hopped up to grow with a pilot who isn't afraid of doing touch and go's. A little more power goes with confidence.
Clark Y airfoil though has it's limitations. Glow fuel isn't getting any cheaper...another feature of an FP-40, sips fuel.

Gotta mix your own fuel.
Find a VP Racing distributor in your area and save 12 to 15 bucks a gallon. Check out the thread that I started. I just burnt about a gallon breaking in a Saito 1.80.

Fuel, LHS or home brew, glow plugs, brand of glow engine, radios, batteries, to AMA or not to AMA, and servos are all lengthy topics that usually don't end with any agreement.
To me it's all personal preference. Beginners and those who are returning really don't need to have things become more complicated.
essixx hasn't logged back in since Nov 28, 2025, so I guess he's on his own either way.

I'm driving distance to Graves RC and they're holding Omega 5% castor blend and 10% Cool Power. ($21.99 per gallon).
When I visit family up in Boston, it's $35 a gallon up there. The difference in cost varies depending on where you live.
I'd sure hate to find a shortage of oil content ruin one of my engines. Excess is problematic as well.
Be sure to shake your jug of fuel each time you go out to fly.

Keep the fuel in the basement if possible. Keep it out of the sunlight and ensure tight caps. Last week I flew an old school Duraplane with a Magnum 46 using S&W 15% 2 cycle fuel. Call Stan at SW Fuels. The fuel I used last week was dated 4/23. Excellent fuel.

I have glow fuel that I is 20 years or more in my garage that I use without any problems.