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Vintage Balsa Mustang Build - Engine Choice

#1
Hello all, so I picked up a Jemco "Fun Scale" Mustang balsa kit at an auction yesterday and will probably be making this my first balsa build, as well as my first glow powered plane. Looks like the kit is from the early 80's or late 70's. It will have a 51 inch wingspan with a finished weight of 3.5 to 4 pounds. I've had a lot of good luck scratch building with foamboard, love flying my FT-Mustang and am currently working on a Corsair. I feel like the build will be a pretty decent first balsa build and I'm excited to make it look beautiful!

As far as getting into glow, I'm struggling a little with the engine choice. The kit says it can take a .19 to a .40 engine (keeping in mind, this was around 40 years ago). I want the plane to be as realistic as possible so, despite the expense and extra complication, I am leaning towards going with a 4-stroke for the better sound and bigger prop (and having better power lower in the rpm range doesn't suck either). Currently looking at the Saito FA-62B AAC, which puts out 0.95hp (just over 700 watts) and goes from 2000rpm to around 11,500rpm, taking a 12x6 to 14x6 prop. It claims to fit easily in any 40 size plane.

Is that engine excessive? FWIW, I am flying near Denver, CO at an altitude of around 5,700 feet. What would you put on something like this? TIA
 

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Piotrsko

Well-known member
#2
Back in the day: a .19 would fly this a bit under powered, almost trainer like. A .40 would do everything a sport flyer should want to do. Bigger gets you into 3D range except the plane isn't capable, but it will be close definitely prop hang.

Prop to ground clearance will be a big factor, a 12" will attempt to cut the grass or groove the asphalt.
 

Chuppster

Well-known member
#3
Personally, I would just grab an LA 40 for $30 and have it rip. I do, however, love my four strokes. Feel free to drop $250 on a glow engine if you'd like, but if I had my heart set on a four stroke I'd grab something like this:

https://www.rcgroups.com/forums/showthread.php?3514105-Smooth-Saito-FA-65!

A FA-62 is going to be plenty of power. You'd be fine with a FA-45 like this:

https://www.rcgroups.com/forums/showthread.php?3504267-Saito-FA-45-MKII-(Low-Time)

I had a Saito 62 (I think) on my Asto Hog (71" wingspan)and it had gobs of power.
 
#4
Back in the day: a .19 would fly this a bit under powered, almost trainer like. A .40 would do everything a sport flyer should want to do. Bigger gets you into 3D range except the plane isn't capable, but it will be close definitely prop hang.

Prop to ground clearance will be a big factor, a 12" will attempt to cut the grass or groove the asphalt.
I didn't think of the prop clearance. Sadly the only smaller 4-stroke I'm finding in stock, a Saito FA 40, has half the horsepower of saitos .35 2 stroke. Maybe this plane is just not appropriate for 4-stroke?
 

Piotrsko

Well-known member
#5
2 strokes have more hp than 4 strokes, but 4 strokes have more torque. Torque is what spins the prop, hp determines how fast it spins. The kits calls for anything from a .19 to a .40 2 stroke . So the saito .40 4 stroke would work, it just wouldn't be screaming fast or prop hanging climbs. Actually kinda scale, come to think.
 

Chuppster

Well-known member
#6
I didn't think of the prop clearance. Sadly the only smaller 4-stroke I'm finding in stock, a Saito FA 40, has half the horsepower of saitos .35 2 stroke. Maybe this plane is just not appropriate for 4-stroke?
The FA-40 would be a good choice for your airplane.

Saito doesn't make 2 stroke engines, FYI.