Gas Engine
 

About to start on a 1/6 scale Sig Clipped Wing Cub, bouncing back and forth between gas or electric Would this gas engine be just fine for this aircraft? Saito FG-11 11cc Single Cylinder 4-Stroke, or perhaps a 10cc. Plane calls for a .40-.45 4-stroke, guessing the 11cc would work just fine but looking for advice from the experienced RC modelers. Found that gas or electric is the norm in the hobby these days as glow is old school.

respectfully,
clc58

A 10 or 11 cc engine in either gas or glow is a bit much for that particular airplane. Mine was a bit overpowered with a K&B .40 glow engine. The Sig kit is intended to build light. While glow is still viable I would suggest going with electric if you don't want to mess with glow power. If you want an airplane that you can hammer on, find a Great Planes Cub and build it with a clipped wing. I had one of those with a .61 four stroke and it was great fun.

Thanks, leaning towards electric.

As best as I can tell, the Satio FG-11-4c engine makes about one HP, similar to a .40 glow and should work well on a 1/6 scale Sig Cub. I would not worry about it being overpowered. It won't be overpowered by all that much, you have a throttle, and a little extra available smash might just help get you out of a jam sometime. The Saito's all-up weight of 25.4 ounces is about 8 to 10 ounces heavier than a typical .40 glow engine with muffler. This might make the plane nose heavy, depending on the battery and ignition location. The electric setup with batteries may also weigh more than a glow engine configuration, but the batteries can be moved around to adjust the balance much easier than adding lead to the tail for a gas engine. As for realism, I've never seen a J-3 Cub fly by going whir-whir. It has always been putt-putt-popity-putt-putt.

As a reference, my Carl Goldberg Anniversary Cub weighs about 7.5 pounds and has been flying very scale like with an Enya .53-4C glow engine (0.8HP) for almost 30 years now (obviously not continuously). It flies about 10 to 12 minutes on 6 oz of glow fuel at half throttle. Glow fuel is still an option at this size. Glow is messy and batteries are not. Gas is only very slightly messy once the engine is broken in and switched to synthetic oil mixes. It is easy to refuel a gas/glow Cub. If a suitable hatch location is not available, the wing might need to be removed to change batteries. Each has its pros and cons. All things considered; you would probably be happy with any of these power options, so get what you like and then fly it like you stole it.

The Saito data I found from Chief Aircraft is:

• Fuel Type: Gas
• Cylinders: Single
• Displacement: 0.66 cu. in. (10.88cc)
• Type: 4-stroke airplane engine
• Bore: 1.06 in (27.0mm)
• Stroke: 0.75 in (19.0mm)
• Cylinder Type: Ringed AAC
• Plug Type: 1/4-32
• Total Weight: 25.4 oz (720 g)
• Engine (Only) Weight: 16.2 oz (460 g)
• Muffler Weight: 1.80 oz (50 g)
• Ignition Weight: 3.90 oz (110 g)
• Crankshaft Threads: M7 x 1
• Muffler Threads: M12 x 1
• Benchmark Prop: APC 13 x 7 @ 8800 rpm
• Prop Range: 12 x 8 - 13 x 8
• RPM Range: 2,000-9,500
• Oil Type & Content: 20:1
• Muffler Type: Cast
• Crank Type: Saito Walbro

Hi!
Its a fairly small airplane (around 160-180cm in span) and I would choose an OS .FS . 40 , 56 or Saito .45 four stroke or an OS .35 AX, La .40 or LA .46 two stroke.
A .40 ball bearing two stroke engine like an OS .40 AX or FX is way too powerfull

I found a review posted on Tower Hobbies for the 1/6 scale Sig Cub using an OS .70 surpass which would probably make more power than a Saito FG 11. The post said:

Stan
5.0 star rating
12/19/22
Excellent flyer
Review by Stan on 19 Dec 2022review stating Excellent flyer. I had one of these for fifteen years. Had a blast with it. Flew so well. Final flight the batteries went dead and it crashed. I flew it with OS 70 surpass and it was perfect power to weight match. If it becomes available I will buy it hands down.

I found an excellent build documentary on YouTube. It has a lot of extra scale detailing that is not shown in the instruction manual Saito .40 for power. Mostly a slide show with a few video clips of the maiden flights. Take a look at:

As you see in the video above the SIG CUB flies just great with a .40 four stroke glow engine! So do not overpower your CUB. That is a very common new-bee solution! ;)

Thank you all for your comments and advice. Decided to go with glow, currently have a bid on eBay for a Saito FA-.40 four stroke. Horizon Hobby has one but on backorder till June, I can wait till then if need be.

I have built 2 of them, and found that a .40 4-stroke is the perfect engine for that plane. First was powered by an OS .40 4-sroke, ~30 years ago. Second was powered by a Saito .40, a couple of years ago. Plenty of power, and it sounds cool, instead of like an angry bee (screaming 2-stroke).

With a Cub, you really need to fly the rudder in your turns. And that rudder is extremely effective. I caution you about doing snap rolls with a clipped wing Cub, as the SIG snap rolls are wicked and violent (kinda fun, too). It is difficult to stop the first one when you want it to stop (be high). And don't horse if off of the ground. It will tip stall.

Finally, land it on the main gear while it is still flying, and don't try a 3-point landing (especially if you have balloon wheels), as it will bounce like crazy.

Remember to post a picture when you are done.

Very nice video, well made IMHO. Thanks

Thanks for the tips on flying a Cub. Not sure how long it will take me to complete the airplane but going to have fun building it and more fn flying it.

I sure will