Engine basics > Four strokes only

Four stroke for a Nobler ARF?

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Mark Mc:
Reading the thread on the main forum about trimming the fiberglass cowl on a Nobler ARF somehow made the idea pop into me head of putting a four stroke in the unbuilt kit I have.  I was originally planning to put a .40 LA-S in it. Perhaps even a .46 LA-S, but that seems overkill.  But since I'm shifting my time more to full scale flying,  I don't know when I'll get to the Nobler.  I have too many kits, and it seems I'll have less time to get to them, at least in the next couple of years.  So I have to pick big things to build if I'm going to take the time away from the big stuff to model.

I have a Saito FA-40, a FA-45, two FA-40a's, and a 26 Surpass.  I also acquired a FA-30, but I don't know it's shape as I haven't taken it apart to check the valves.  Also a Magnum 30XLS.  The FA-40 and -45 seem awful heavy.  Not sure if the -40a is too heavy.  I don't know if the .26 Surpass has enough oomph for a Nobler.  The 30XLS might be a choice, but it seems pretty heavy also.  Maybe the FA-30?

What do Y'all think?

Mark

Colin McRae:

--- Quote from: Mark Mc on February 14, 2025, 02:02:37 AM ---Reading the thread on the main forum about trimming the fiberglass cowl on a Nobler ARF somehow made the idea pop into me head of putting a four stroke in the unbuilt kit I have.  I was originally planning to put a .40 LA-S in it. Perhaps even a .46 LA-S, but that seems overkill.  But since I'm shifting my time more to full scale flying,  I don't know when I'll get to the Nobler.  I have too many kits, and it seems I'll have less time to get to them, at least in the next couple of years.  So I have to pick big things to build if I'm going to take the time away from the big stuff to model.

I have a Saito FA-40, a FA-45, two FA-40a's, and a 26 Surpass.  I also acquired a FA-30, but I don't know it's shape as I haven't taken it apart to check the valves.  Also a Magnum 30XLS.  The FA-40 and -45 seem awful heavy.  Not sure if the -40a is too heavy.  I don't know if the .26 Surpass has enough oomph for a Nobler.  The 30XLS might be a choice, but it seems pretty heavy also.  Maybe the FA-30?

What do Y'all think?

Mark

--- End quote ---

I have the 26 FS Surpass on a smaller Yak-9 (40" wing and 32 oz) and it is a great combination. But IMO the 26 will not be powerful enough for a Nobler ARF. A 30 size, maybe. A 26 or 30 will allow it to get airborne but probably struggle to do basic stunts.

A 40 size FS would be powerful enough but too much weight up front. I have an OS 40 LA on my Nobler ARF (49 oz), and it is very nose-heavy needing 2.5 oz of lead in the tail to CG balance. A 40 FS is heavier than the LA and will need even more tail lead. All going in the wrong direction weight-wise for good flying characteristics.

On FS powered models I have, I moved the engine back to account for the increased engine weight to keep it from being nose heavy so I wouldn't have to add tail lead. Not impossible, but it would be difficult to move an engine back on a Nobler ARF without lots of cuts into the model. But on a positive note, you would be able to get by with a much smaller fuel tank since FS's are more fuel efficient.

And an OS 46 LA is definitely overkill for a Nobler ARF. I'm about to try out the new Enya SS 35 CX ABC-BB engine on my Nobler ARF to see how it does. With the lighter Enya 35 and corresponding removal of some tail lead, the Nobler ARF will weight close to 43 oz, down from 49 oz with the 40 LA.

M Spencer:
Maybe put on the 26 , sidemount , lower .

Depends on the line length , but if your up past 50 ounces , it wont fly slow . Youll need a shorter nose too.
Id peel it all back and rework from the firewall / L E , fwd.

they all say you want 5 degree outhrust on the 4 strokes . and a longer undecarrage .

Otherwise a FSR 25 2 strokes a good set up , to get the pilot to earn his keep .

Dennis Toth:
Colin,
The Nobler flies best around 43 - 45oz. with the 2/3 flap elevator ratio (more elevator than flap, it has a short tail moment). Now the 26 would work, it is about like a Fox 35, but you would need to go with 20% N fuel and a wide blade 9x6 prop. A Satio 30 would be better as it is lighter and a bit more powerful. To get the weight out you could shorten the nose for the FS by 1"ish, use a plastic tank, use a wood prop and plastic spinner, use foam wheels. To get the right nose length you could remove all tail weight and the engine. Get a blob of clay the same weight as the engine (could use the engine be careful not damage the fuse) and move it along the nose to get the right position for the engine, mark the length and adjust from there.

Best,   DennisT

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