Prop failure

[Ron Gray]

Aw, c’mon guys let’s be a little bit more light hearted, all things appear to have been said in jest / tongue in cheek!

[alex nicol]

Looks to me like the joys of communication by the written word. It's so easy to write something one way only to have it interpreted another way.

either way looks like somebody might not be getting any more new engines of a particular type :0) ..........joking, honest

[Ronaldo]

On the subject mentioned earlier of the ali spinner drifting on the back plate and the 'cut out' edge fouling and digging into the prop hub, I've had this happen with and without using a starter. Now I 'peg' the back plate by drilling and tapping into the edge where the spinner edge sits in the groove, and fitting a m3 x 5mm grub screw, securing with a drop of thin cyano. I then fit and line up the spinner and prop against the back plate to give good clearance so as not to touch the prop hub, then file a notch in the spinner back edge/rim to fit over the grub screw. Never moves now, even when using heavy duty starter.

[Robert Welford]

Posted by Ronaldo on 14/08/2019 10:54:33:

On the subject mentioned earlier of the ali spinner drifting on the back plate and the 'cut out' edge fouling and digging into the prop hub, I've had this happen with and without using a starter. Now I 'peg' the back plate by drilling and tapping into the edge where the spinner edge sits in the groove, and fitting a m3 x 5mm grub screw, securing with a drop of thin cyano. I then fit and line up the spinner and prop against the back plate to give good clearance so as not to touch the prop hub, then file a notch in the spinner back edge/rim to fit over the grub screw. Never moves now, even when using heavy duty starter.

I've just starting flying a Toni Clark (TC) CAP21 with a Zenoah 62. I'm using a carbon propeller together with a TC spinner. The spinner is epoxy grp with a nylon back plate. I notice after running the propeller rotates slightly relative to the spinner. The engine is hand started. I tighten up the single prop bolt as tight as I can, but the problem is that the surfaces of the propeller and spinner backplate are smooth. The Zenoah's prop driver is serrated.

I thought of making a double sided washer from 120 grit glass paper placed between propeller and spinner backplate. Anyone any other suggestions?

[Jon H]

I have made numerous sandpaper washers and they work really well. I used 240 and 400 grit so far, both worked fine.

I have had the spinner cone come loose on the model once or twice before and there is very distinct ringing sound when that happens. That sound was not present this time and there were no fret marks on the prop or spinner mating surfaces.

[Robert Welford]

Posted by Jon - Laser Engines on 14/08/2019 11:58:07:

I have made numerous sandpaper washers and they work really well. I used 240 and 400 grit so far, both worked fine.

Thanks Jon. I will go this route.

[eflightray]

Prop damage happened to me quite a while back, the frightening thing was the spinner was actually hiding it.

Electric power, APCe 15" x 8" prop, plastic spinner. The prop clipped the grass during take-off, the sort of prop ground strike that can happen when taking off with a tail dragger.

The only reason I checked the prop was because it sustained slight tip damage.

It was not until I took the spinner off I could see what had really happened, the split was on both blades.

Ray.