ORIGINAL: teamvortex
Steve -
I'm at a loss to understand what difference it makes on expo as long as the ratio is kept the same (2:1 in your case).
True, if you use 5/8" and 5/4" instead of 5/16" and 5/8", the force into the pushrod is only half of what you have, however, the torgue from the servo and into the surface is the same. Unless there's some serious friction in the rotation axis of your linkages or bending in the pushrods, it shouldn't make a difference. Actually, if there's a pushrod bending issue, the shorter arms would make it worse. What am I missing?
Rich
TeamVortex
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You nailed it.
I'd rather fly a model with great linkage and sport servos than a model with great servos and crappy linkage.
I have flown sixty powered competition pattern aircraft with Kraft KPS-15 and 14 servos, only changing out the stock pot wiper to a Giezendanner unit. Those servos provided only a little more than half of the power that modern sport servos provide.
The Futaba FPS-148 with ball bearing kits do a wonderful job with adequate torque for average sixty powered models.
I have gone JR in recent years and I use a variety of their servos. My best servos at the moment are 4721 JRs. I'll upgrade one of these days, but not until I truly need to do so. Spending a lot of money on servos to control old fashioned pattern planes isn't on my agenda. Good servos? Yes. Competition grade, state-of-the-art servos? No. I think the money can be better spent elsewhere in the hobby. But, of course, this is just my opinion.