Background.  In the world of small - usually foamy - R/C models, a lot of the small motors intended for that application include or recommend using a "prop saver".  For those of you that might be unfamiliar with these, the prop saver is a small, usually cylindrical piece of metal that slides onto the prop shaft, usually held on with set screws.  Usually there are two screw heads one on each side where the screw is aligned perpendicular to the motor shaft.  The thinking is that you fit a prop onto the motor shaft, but actually hold it in place with a small elastic ring running from screw head to screw head, across the front face of the propeller.  This mounting allows the prop to depart from the shaft in the event that the prop makes an unplanned acquaintance with the ground.

Finally, my question.  Has anyone used these prop savers for small e-C/L models?  Any opinions or pros or cons.

I'm considering using  one of these small motors from my stash on a 1/2A sized model of 150+/- squares.  When I pulled it out to lay over the plan, I realized that all my bigger models have used compression collets, so this is the first "return" to recommended prop savers.

Thanks,
Jim Howell

Hi Jim
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On the small models the prop saver works when models nose over on landing, but not on straight in crashes!
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I am well acquainted with the different responses of the prop on prop savers.  I think I've tried the majority of "Ground contact angles" in the past.   

As for saving the prop, some angles work well, some do not.  And the age of the elastic makes a big difference.

Let me know how the Streak works out and whether or not the prop departs on a hard corner.  A Baby FS was what I was thinking about working up for one of these small motors.

Thanks,
Jim Howell

I've used prop savers on some of my "1/2A" sized models. You can't let the RPM's get too high, and I usually don't go over 2 cells when using them. The attached picture of my P-38 using prop savers, The motors are about equivalent to a .020 I don't remember the RPM's but about 11-12K I think. Not an aerobatic airplane but fun to fly.

I have also used the on the TBF and B-390, again with 2 cells only. They both use the Tower Pro 2408 when on 2s and prop savers.
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John,
Thanks for the comments and pics.  I really like your TBF!  That 12K number is my target for the small motor.  It is a Lil' Screamers, Purple Peril, kV=1540.  The marketing pitch says that it is good for 3D RC flying with 3 cells and an 8x4 direct drive.  And it has that prop saver included, with no restriction on use at full voltage.  So, that says the manufacturere is willing to go on record that the prop saver is to be used at up to 16K.  Even at 75% on a 3S only yields around 12500 and I was thinking along the lines of a 7x5.  Regardless of marketing, I'll give it a try and see how it works.
Thanks,
Jim Howell

I HAVE A PROBLEM WITH USING A PROP SAVER UP TO 16k, My tower pros WILL TURN that and I have had them spin props off a prop saver set up

Have you tested the purple peril yet or are those manufactures specs?

PS Here is a good link re prop savers http://www.rcgroups.com/forums/showthread.php?t=1419378&highlight=prop+saver

John,

No, I have not used a prop saver on the purple peril.  The 3-cell at 1540 kV is manufacturer specs.  I was uncomfortable with the whole prospect.  I've used the PP in an electric Free Flight, but there I used a folding prop hub, not the prop saver, and on a 2-cell.  I knew I wanted to use the 2-cell, and got the higher kV PP specifically for that context.  I've used prop savers on low RPM geared brushed & brushless motors, but nothing at this high an RPM.  I have no doubt that a prop will spin off, especially when the elastic gets older and more brittle.  I'll check out the rcgroups reference, thanks,

Jim