Motor/GearBox/Prop question.... - RC Groups
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May 04, 2001, 04:06 AM
Registered User

Motor/GearBox/Prop question....

Got my Virus 400 in the air today. Boy is it a great flyer!!! It can fly very slow with plenty of power of loops. With the light wing loading it leaps off grass in a few feet.

The only issue is the gearbox that it came with is not great. It vibrates and full throttle and there is too much slop in the mechanism for clean power transitions. The stock set up is a multiplex 400, 3:1 gear and an 11x4.7 APC. I'd like to get a Graupner "1700 Series" Gear Drive at 2.33:1. Will I still be able to swing the 11x4.7 prop? I am currently using an 8 cell 600AE pack, but also plan on getting an 8 cell 1100NMH pack. I love the look of the large prop and would like to use it if possible.

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May 04, 2001, 09:23 AM
Space Coast USA
hoppy's Avatar
Have you balanced the prop?
May 04, 2001, 09:58 AM
Mitch G's Avatar
I think an 11x4.7 will be too much prop for a 2.33 GB. (Motocalc shows 13.9 amps static with this combo. It shows 10.4 amps static with your 3.1 GB.)
According to motocalc, a 9x4.5 with a 2.33:1 GB will give you the closest match to your 11x4.7 and 3:1 GB combo as far as amps draw is concerned.
(Note: I don't know if 9x4.5 props are readily available or not.)

I personally have had good experience using a 9x6 (11.3 amps static) and an 8x6 (9.1 amps static) with a 2.3 Mini Olympus GB on my T-52.

May 04, 2001, 10:02 AM
Registered User
Yup, Balanced the prop.
It's just a CRAP gearbox. The small flange mounts and slop make it very unstable. I guess I could glue the gearbox to make it better, but I'd rather not permanently affix it. Looks like I'll go with a Graupner BB Aluminum gearbox (then I can get a 3:1 ratio). I just can't wait to fly it again!!!

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