Anybody seen the L-19 geared sp400 model in Model Aviation this month? - RC Groups
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Mar 03, 2002, 11:30 PM
raythomas's Avatar

Anybody seen the L-19 geared sp400 model in Model Aviation this month?

I would really like to build one of these. I am only experienced in sp400 directdrive. What are some of the best gearbox, gearbox ratios, and props that some of you fellows use on your sp400 scale models? Thanks Ray
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Mar 04, 2002, 04:13 AM
Professional Goofball
OCModels's Avatar
My favorite gear box for the 400 motors is the Graupner 1700 series gear box geared 2.33:1. I especially like the way the gear box has ears to mount the box to two rail sticking out just like most IC engines. makes for super simple installations...

Last edited by OCModels; Mar 04, 2002 at 04:15 AM.
Mar 04, 2002, 04:25 AM
Professional Goofball
OCModels's Avatar
Sorry... I only answered one of you questions. The motor you see in the picture will be running off 8 600ae cells turning an 11x7 prop. Now before everyone starts writing about how the prop is way too big for the motor, don't bother. I'm still going to run that prop. I have done many bench test and see no reason why this prop/battery/motor won't give me the performance and flight duration I'm looking for. This is a slow flying plane so the larger prop will give me more scale like persormance. Plus, the prop looks great on the plane to boot... A 9x7 prop would also work fine for most sport planes.
Mar 04, 2002, 12:16 PM
Registered User
E-Challenged's Avatar

Geared 400

Another choice is the common Mini-Olympus 2.3:1 gearbox. These are kind of noisy in a pleasant motor sound way. I have been running this with a 6v S400 and 9X5 Graupner Slim-prop in a 54" Comet Aeronca on 8 or 9 500AR cells, good power for ROG's and 10-15 minutes duration with throttle mgmt. Mounting is similar to Graupner. I use an 1/8" ply plate withblind nuts to mount gearbox to. Nose bowl is removable and I have a hatch on top of cowl so motor/gearbox is easy to remove and service.
Mar 04, 2002, 01:03 PM
Registered User
SchiessCo's Avatar
I just ordered up a set of the Bird-E-Dog plans. It's a cute little sucker.

My favorite geared combos for 6V Speed 400 motors are either a 1.85 gearbox with an 8x6 APC E-prop, or a 2.33 gearbox with a 9x5/6 Graupner slim prop or APC e-prop. Both work well with 7 or 8 cells, but I like the 1.85 8x6 combo the best.

I really like the Graupner gearboxes. They're a bit more expensive than the Olympus or MPI gearboxes, but they're smooth, quiet and solid.

Hope this helps,

Mar 04, 2002, 03:21 PM
Superhero, Third Class
astroboy's Avatar
I second E-Challenged's Mini Olympus choice(I use an APC 9x6E and 8 cells). It mounts similarly to the Graupner, and is really durable.

Mar 06, 2002, 01:10 PM
Registered User

Be Careful Not To Strip Mini-Olympus Pinion Threads

I got two Mini-Olympus gearboxes some years ago, and I like them. The only problem I had was that I stripped the setscrew threads in the plastic pinion. Fortunately, I happened to have a couple of brass pinions salvaged from a couple of Radio Shack mystery gearboxes. The fit was perfect! Short of that, I could suggest that you fix stripped threads by applying a dab of thin CA glue with a pin to the threads. When the glue has set, try running the setscrew in. Or try using green LokTite to secure the pinion to the motor shaft, as others recommend for brass gears on 280 motors. Do a search, and you'll find plenty of info on such a method.

Some complain that the Mini-Olympus gears are noisy. I don't mind the noise. Sometimes the noise is the only cue I have that the motor is turning the prop!
Mar 08, 2002, 08:59 PM
raythomas's Avatar
Have any of you ever tried the APC 8x4E or the 8x6E props?? My LHS has several of these in stock, but he doesn't carry any of the graupner cam slim props that everybody is talking about. Do any of you use the APC slowflyer props on sp400 geared? I also am curious, if you used a 8x6E prop on a 2to1 geared sp400 and then changed to a 2.5 to 1 would there be a really noticable difference in power or thrust?? Thanks Ray
Last edited by raythomas; Mar 08, 2002 at 09:04 PM.
Mar 09, 2002, 07:55 AM
Registered User
Paul's Avatar

I use the APC Slowflyer props with the 2.33/1 box and love them. My favorites are the 10x4.7 and 9x6 with 7 or 8 cells.