Im not a beginner but I figured this would be a great place to ask. Im running an OS 75 AX. I bought the plane used and realized the backplate on the aluminum spinner was crasked in four directions. Do you guys use plastic spinners on motors this size. I saw where they dont recommend plastic spinners over 14000 rpm but I shouldnt be hitting that. It has a 13x7 on it right now but will soon get a 14x4w. With using a wide prop its easy to trim a plastic spinner. What size spinner would you guys recommend? The one that was on it was a 2-3/4. Im not sure if it needs one that big. Or is the size more for looks. I dont mind buying a new aluminum one but I want to fly tomorrow and the LHS doesnt have aluminum ones that big. Please help!!!!!!

While I'm not sure about the material selection (plastic vs. metal for a .75 size), I will say that spinner size is based on the shape of the fuselage of the plane. Choose a size that looks good on that plane.

I have plastic spinner on a .46 2-stroke, and a metal spinner on a .91 4-stroke. Personally, if it was a nice plane, I'd go ahead and get a metal spinner for a .75, but I would imagine you'd be ok with a plastic one too, especially if you want to fly with a spinner by tomorrow.

No problem with plastic ones.

Some people complain that plastic spinners tend to score easily due to the starter.

I found that if this happens, you are merely using the wrong starter cone, or the wrong starter cone material.

After changing my starter cones out fo a softer silicon cone ( and keeping them clean! ) I have yet to even mar the shine on plastic spinners, up through 3.25" in size on engines as big as 1.80 four strokers.

I choose the spinner based upon the look on the airplane, or what I want it to do. Most are the exact size required by the coweling on my planes, but I have a 3 incher on my .46 mach 2 because it is as wide as the fuselage and helps the plane fly faster.

The plastic spinners with the plastic spinner plate shouldn't be used at all on any plane, I have seen so many of these junkers break and fly apart it scares me if I have to pit next to one of there users. I do use the nylon spinners with the metal back plate on my big planes that get hand started. I have a big box of them I picked up at an auction so I use them. These are nylon, not plastic. If I have to go out and buy a spinner I buy a good metal spinner, why fool around with anything else. I started using Magnum spinners due to the cheap price and found them to be as good as any other spinner, better then the ones sold through tower. My LHS sells them so I have no problem finding the size I need. The spinner size is dictated by the plane itself, you want the back plate to be the same size as the cowl nose.

They fly apart, because they are improperly installed.

Normally the backplate is cracked because the user has installed a prop that pushes the blades back against the backplate, causing it to bend and stress. This will just as often happen with aluminum spinners as well, particularly those with "lips" along the edges.

A plastic spinner tends to be lighter, and has lower inertial forces acting upon it to tear it apart, so it may actually fare better than some of the aluminum ones.

I've seen both types come apart, and it has always been because of improper installation/usage.

Only metal spinner I have ever seen come apart is during a crash. The cheap plastics all the time. It doesn't mater to me about the whys of the problem, being over tightened screws, starter force or a prop hitting the back plate. I have had too many pieces flying past me to ever tell someone to use them, just spend the few extra bucks and buy a good one.

It's not so much a matter of "buying a good one" ( though there is never anything wrong with that ), but one of proper installation.

No matter what you purchase if it is improperly installed, it can be dangerous.

I've seen this happen with some nice high end spinners, where the user made the mistake of cracking the back plate.

Fortunately no one was in the line of fire, so to speak.

There should be no stressing forces on a spinner, be it aluminum or plastic. If not something is wrong.

I agree. Unfortunately, there are people who can break anything!

Spinner size and shape is determined by the plane, and by your preference.

I prefer aluminum spinners but use nylon on some models (I prefer the price of nylon). I've used nylon spinners (with nylon backplates) on .61 two strokes and ,91 four strokes with no issues other than I dislike having to custom cut the slots. I do it but it is not something I enjoy.

If your plane has a cowl, you will probably want to choose a spinner that blends nicely with it.

If you do not need to match a cowl, it is 100% YOUR preference. Tru-Turn makes "wide blade" spinners in many shapes and sizes. This page shows samples of the shapes that are available. http://www.truturn.com/Spinners/By_Shape/by_shape.html

This link is to a 2.25 inch 'ultimate' spinner with wide slots. I like the pointy shape of the 'ultimate' design. You may hate it.
http://www.truturn.com/cgi-bin/store...exact_match=on

There are choices other than Tru-Turn, they are just the one I have bookmarked on this computer. Tru-Turn will custom cut any of their spinners to fit any prop. I think Dave Brown Products will also custom cut their spinners to fit any prop.

Again, if you are not trying to match a cowl, or a scale shape, pick the one that looks best to you because your opinion is the only one that matters when it is time to spend money.

Maybe you do not need a spnner at all. I really like aluminum or brass prop nuts for planes that do not need a spinner. Here are a few examples that will fit a 75AX
http://www.truturn.com/cgi-bin/store...exact_match=on
http://www3.towerhobbies.com/cgi-bin...?&I=LXE192&P=0
http://www3.towerhobbies.com/cgi-bin...?&I=LXK242&P=0
http://www3.towerhobbies.com/cgi-bin...?&I=LXL731&P=0
http://www3.towerhobbies.com/cgi-bin...?&I=LXCC41&P=0

After looking at the cowl and measuring anything under 2-1/2 would look odd. Luckily a friend has one I can get to get going fast. Thanks for the help.

What is your routine on cleaning? After each session? What do you use as a cleaning agent?

Thanks!

-MA

I just use Windex on them.

I find that the cones which are included with most electric starters use a substance that tends to accumulate particles.

The stuff gets imbedded, and further helps to scratch the material, be it plastic or aluminum.

The softer almost gel like cones leave no scratches at all.

I find that I wear them a bit faster though, but not overly so.

Which ones are the "gel-like" ones? Any help here?

I am about to place a tower order and had [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFT96&P=7]this[/link] in mind. Thoughts?

-MA

Most of the 'Silicon" rubber cones tend to be softer and less prone to scratch.

I usually go in an check them out an my LHS.