Plastic spinner danger

[andreas johansson]

Hi all

On my Nobler with a B40 engine I have used a plastic spinner up until today. For no apparent reason the spinner exploded and sent plastic shrapnel all over the place. Fortunatly I was behind the aircraft, but if it had happened 10 seconds earlier when I was in the front of the aircraft god knows what would have happened, I could have been blind by now....
The spinner wasnt old, crashed or anyting. It was made by a well known company.
I have now turned to Tru-Turn for their products instead (as I did several years ago with my rc pattern aircrafts). Ordered a 1-3/4" Tru-Turn aluminum spinner from Tower a couple of hours ago.

Be careful out there!

Andreas

[Paul Taylor]

Andreas,
That is not a good thing. I would like to know the brand so maybe I can check mine.

Maybe it was for electric use only?

[Dennis Adamisin]

Andreas
Wow that IS scarry - thank God you are alright.  I have heard of that happening with plastic spinners on very high RPM engines but certainly nothing like a stunt 40.

Was it a plastic backplate or metal?  Snap on or bolt on?  Screws through backplate or a single screw in front

Oh heck, what BRAND was it?

[Steve Helmick]

On SSW, he replied to the question with "DuBro".  I like DuBro products very much, but spinners need aluminum backplates. Take a look at the Great Planes Nylon/Aluminum spinners on Tower's website or annual catalog. They're $7, work well, and are pretty easily the lightest spinners (in the mass market sense) that I can think of. Lighter than Randy Aero's, Brodak's, Tru-Turn. Dunno about the carbon spinners from Stalker and whoever else.

The only real disadvantage is that they only come in 2 blade prop models. Colors are nice, some locals have polished the nylon after starter burns, and others have painted them after scuffing up the finish. Mike Haverly modified one of the backplates to fit a DuBro spinner cone (2 new holes) for 3 blade props, so it can be done!
  Steve

[Paul Taylor]

I think he posted this over on SSW.
Du-Bro spinner.

I think the vendor should know about it.

[Steve Helmick]

Not a bad idea, Paul. How about copying and pasting Andreas' post into an email to DuBro? There would probably be concerns about modifications, abuse, etc., but I'd think they'd be appreciative. Tag: You're it! Steve

[bbaker]

I had a Dubro spinner do the same thing last year on an LA 40 at about 9500 rpm it just came apart was thinking maybe I overtightend the screws

[Richard Grogan]

Did the front cone have missing or loose retaining screws, and the prop chewed it up when it detached from the backplate, maybe? Thats what it sounds like.. Pretty scary, regardless! 

[john e. holliday]

I myself am about to swear off the DuBro spinners as I have just trashed the third one with a backplate that was coming apart.  I have always tried hard to make sure the prop was not touching anything when the screws were tightened down.  All three spinners were the 1 3/4 inch dia. size.  Have not noticed any thing happening with the larger spinners like 2 or 2 1/4 inch. 

As Ty says the plastic spinners does make a cushion when the plane goes straight in.  I do have one of the new spinners with the metal backplate that seems to be holding up okay.  Have fun,  DOC Holliday

[andreas johansson]

Hi

Sorry for not revealing the brand directly, but I see that you found it out.

Richard: No, both screws are still attached to two small pieces of the remains of the  backplate.

I have, even after this incident, full trust in Du-Bros other products and I have used a lot of their spinners in the past without any problems. This could probably have happened to any brand of plastic spinner. For me, I'm finished with plastic spinners of any brand.

Andreas

[Dennis Adamisin]

A lot of the plastic spinners use self-tapping screws into plastic - if you overtighten it strips out the screw.  The Dubro's use metal lock-nuts embedded in the backplate - thus they can be tightened a lot more without striping the threads.  Ironically I like using them because of the metal threads that cannot be stripped out.

Some of the plastic spinners use metal backplates with tapped holes - again they can be tightened a lot more than the self-tappers can without stripping.

As Ty said, a small tear in the plastic (possibly around the screw) can turn into a catastrophe pretty darned quick. 

[John Stiles]

Send all your old/unwanted spinners to this old disabled vet...none of my motors turns up that kinda rpms.......I'll post my address if anyone needs to know.

[Bob Reeves]

I've had one DuBro plastic blow up using a starter on a four stroke. Forensics determined I didn't leave enough room between the fuselage and the spinner back plate. Fixed the clearance problem, replaced the spinner and no more trouble.

My personal preference is for Brodak spinners but sometimes a white or black plastic looks and fits better. What I don't like is the inset on the back of Dubro spinners, once you set up an airplane for one your stuck unless you can move the engine back to use a flat back plate spinner. On top of that the inset is different between the 2 and 3 blade Dubro's, just enough to make switching a PTA.

[Howard Rush]

I use 2" DuBro spinners.  I don't tighten them too tight, mainly out of fear of misalignment.  They seem to be made of pretty good stuff.  The only problem I had with one was when I forgot to put in the screws.  The spinner fell off when the engine started, but kept getting sucked back into the prop.  After the spinner hit the prop a few times, neither was in very good shape.