I'm a newby. My question is about spinners. Are there limitations regarding the type of spinner used vs the size of the spinner, the rpm of the engine used or any other limiting factors that I'm not smart enough to ask? I'm thinking of plastic, plastic with an aluminum backplate and aluminum.

My experience running 1 1/2 in spinners on a TD 09 is that the Carl Goldberg snapons will eventually come apart in flight. The Dubro plastic with bolt on front work fine. The Goldberg spinners work OK with lower RPM engines.

Limits?? No.

Spinners are used for a number of reasons Appearance, Streamlining, Safety and Balance.

Appearance; they look nice and you can colour coorinate them with your plane.
Streamlining; something of a debate, when in doubt refer to Appearance.
Safety; another debate, better to be hit by a smooth nosecone than a rough propnut, but the propeller is right there to cut into you so damage will be done regardless.
Balance; If the AC is tail heavy a heavy spinner/propnut can make the differance in balancing the Plane, conversly a light spinner can reduce the weight in the nose.

Buy a spinner that fits the AC, engine and prop, plastic works just fine.

If you develop a crack, loose a chip discard the spinner immediately. They can explode and send shards flying, as well as damage the engine.

As far as size goes, Let the airplane decide the size, not the engine - that is to say, you wouldn't sat "What size should I get for this engine?" but rather, "This plane calls for a .40 - .46 2-stroke, or a .52 - .70 4-stroke and a 2 1/2" Spinner."

Now granted, on some planes you have some leeway as to spinner size, so you can vary it a bit, but on others you don't (See Pic)

As to what materials, for most of the engines we use from .049s up to 150 4-strokes, I have never had a plastic spinner fail. Of course, An Aluminum Spinner sure looks sweet, but on those type of engines I only use them for looks.

Now if you get into really big stuff, or extreme speed, you may want to use something better than plastic.

I agree with what Minnflyer has to say. I too have never had a plastic spinner fail. I avoid the snap-on type of spinners because I have seen them on others planes and they can come apart. Aluminum spinners are very nice, but more costly. But they look oh so sweet when you polish them to a mirror finish!!

Ken

I have seen an aluminum spinner take the whole front end off an aircraft before. The pilot had a rough landing the flight before and had a small dent/crack in the spinner. The next time the engine was started the damaged portion of the spinner was shed and the vibration shook the front end right off his bird, thank god he had enough sense to get out of the way, unfortunately not enough to kill the throttle first.

That being said I still use aluminum spinners, but any kind of rough landing and I look that spinner over very carefully before it runs again.

I read in some old magazine the advice that the spinner should cover 1/5 of the prop diameter for maximum streamlining. That would be a 2 inch spinner on a 10 inch prop; sounds about right.

I've had two odd things happen where the TD09 airplane went straight in (from not very high) on hard ground. Shattered the plastic spinner, broke the prop, but no damage to the rest of the airplane. Something to be said for that.

Jim

This aluminum spinner saved this OS .91Fs from certain damage.

FBD.

Dave - a lil bondo shoudl buff that right out. :-)


I have a friend have the backplate on an aluminum spinner come to pieces and send shrapnel everywhere at high RPM on the first runup after being installed right out of the package.

Examination of the parts seemed to indicate that the backplate was made of a cast aluminum instead of a milled or machined type construction from bar stock. He called the out of town hobbyshop and explained, and the guy running the shop replaced the spinner with a new Tru-Turn no cost to him, even theough there was over $10 in price difference. He said he had bought the cheaper spinners from a generic distributor and was going to send them all back after that.

Since then I make sure that my spinners are described by the manufacturer as a machined, or spun aluminum construction.

Dave that is one of the reasons that I still use them, but any kind of ding and I replace them, I only had to witness it once thats enough for me. LOL

Literally it shook the whole front end off of an Ultra Sport 60.

Ya forgot one Bruce -- A spinner can improve the efficiency of the prop & engine combo. The spinner hides the grossly inefficient root-transition zone of the prop from the slipstream. This reduces the load on the engine & increases RPM in the working length of the prop -- generating more thrust.

Spinners can be sized up to ~ 25% of the diameter of the prop without causing a loss of efficiency through hiding the functional portion of the prop blades.

I have had this happen twice. I go to use my starter and the spinner and prop break loose and had I not stopped them they would have spun right off the hub. Luckily, the motor didnt start. Now both times the nut was very tight, but I had to cut the spinner a bit to allow the prop blade to sit nicely in place. "Composite props both times" I assume that I simply didn't relieve enough material and that the prop must have been touching the spinner a little bit, would that be a correct assumption?


Tom

I had a plastic spinner explode on me while hand cranking a Saito 91 and it was somewhat scary. I had flown the airplane 20 to 30 times. However it was a single occurrence in many, many years of flying. I put a spinner shaped prop nut back on the engine but still run plastic spinners on other engines.

Bill

I didn't know that, I'll add it to my list of little known, but interesting facts.

Thanks.

had a plastic (dubro?) spinner shatter on an os 91fs (using a starter). they are not recommended for 4 strokes.

Sounds more like a flooded two stroke or a backfire in a four stroke rather than a spinner problem.

hi there britbat

im in a bit off a pickle ive just bought a three bladed carbon prop and a carbon spinner whicht has not been cut yet could you help with any suggestions on how to cut this without ballsing it up as spinner was expensive could yourself or anyone give me some tips

kind regards graham b...

After trying Dubro and Goldberg plastic spinners my favorites are from Hobby Lobby. I don't know who makes them (they look like Flair spinners) but they are very easy to use and very tough. I strained an old Cherokee ARF through a tree at full throttle and the only thing unscathed was the HL spinner. I like their shapes too--tend to suit most scale types better. Jim

I had a 91 Satio on a 4*60 and could not deep a spinner on it not matter what make or type,went to a heavy hub and no morre problems.Now I have a 91 KG and looking for something to put it on.I have seen the plastic ones explode just using the starter,yes you have to check them good each flight,those flying pieces will leave a mark.

or its getting spun backwards... i have seen a plane, electric picco jet i believe, fly with the prop on backwards.... was doggin really bad and slow but the plane still went forward!...

so we have concluded that plastic or alum, there has been problems with both so neither is 100% safe..... so prop size and shape are the things to pay attention to?

Like BillS I have seen a plastic spinner come apart on a Saito .91. Luckily no one was hurt but it was scary. It threw pieces of plastic shrapnel everywhere. I suppose it could happen on any engine but personally I won't put a plastic spinner on 4 strokes.

I only use plastic spinners with alum backplate, a little more $ but woth every penny IMO

I used to prefer the DuBro plastic spinners, but after buying a couple of aluminum spinners, I haven't purchased another plastic one.

They have excellent prices on very nice spinners here:
http://www.maxxprod.com/

I'm flying several of them, and they are all holding up fine. Great price! The "name brand" models are too expensive for me.

Good flying,
desmobob

I've only used a couple spinners so far, but each one of them I have had to trim to get the prop to fit and that worries me about the integrety of them. Not that I do a bad job of trimming, its just that when you start to cut into things, you are kinda walking off the "safe" path of it. And without the right type of balancer it could go "unchecked" and lead to failure problems like its been mentioned.

In 10 years in this hobby I can't recall a spinner that I didn't have to trim in some way. And I've never had a spinner fail yet. The little bit of material you are taking off of the spinner isn't going to affect it's structural integrity at all. Go ahead and trim it to fit your prop, you'll be just fine

Ken