How do you determine whats the best spinner size? Can a spinner be too big? Can it be too small?

I'm putting together a 50cc YAK and I'm not sure what size spinner to buy. 3.5"? 4"? Does it even make a difference?

Look at a picture of a full scale Yak and visualize. Either of the sizes you noted will work, as would a 4-1/2". Each full scale Yak is a custom build so what's up front is the choice of the buyer.

It looks to be pretty big on the full scale aircraft compared to cowling size....
So then it makes no difference at all really.

Here's a photo of a 54 that I found and I had a 3" tru-turn special in a parts drawer that is close enough for me. The spinner is on my 87" span 50cc Yak

The bigger the spinner the faster it will go. As in Rear Bear.

Whats the best Spinner value in terms of strength versus cost?

Glass/Fiberglass? (seem to be the cheapest)
Aluminum (the strongest maybe?)
CF (the lightest?)

Are most folks using Aluminum?

well they are all going to be strong enough. It's personal preference really. Personally I use CF

Yeh, I don't have any preferences...thats the problem.

CF is bit expensive for me. @$70 thats 1/10 the cost of the engine. [X(] I guess Aluminum as it seems like whatever one else has.

well considering your name I would think you might be concerned about wieght... I would be going fiberglass 2 or 3 ozs adds up.. do that 5 times and thats a pound,

Yeh, the MPI Aluminum and glass are right at the same weight it looks like. The CF is lighter but out of my budget range.

How difficult is it to dremel aluminum though to fit the prop....that seems like a real bunch of work there.

http://www.espritmodel.com/index.asp...OD&ProdID=4628

They have CF as well...Im using the 5" and 4" both are very good and half the price and weight of a tru trn

$33.00 for a 3-1/2" fiberglass spinner and lightened aluminum backplate at Esprit. They're out of C/F in that size right now. I've used both in various sizes and continue to use both. Excellent products, very light, especially the fiberglass, inside of backplate raised and cross cut for good propeller securement, and easy to cut. I won't use about anything else now.

To cut an aluminum spinner you need Carbide bits for your dremel. And a small tube of synthetic grease. Put some grease on the bit so the aluminum will not stick. Re- apply the grease now and then. If you do not know what you are doing stay away from CF spinners. The dust from cutting them is wicked. They do not stand up to abuse. They need to be inspected every flight. It takes about 5 applications of loctite to get the bolts to stay tight.

Jeez, I never had that much trouble getting the screws to remain secure with the Esprit versions. I guess your "Petes" spinner must be a little different.

Got over 300 flights on my Pete's model 4" with no loctite... maybe I am doing something wrong?

SS............ Totaly agree. I soaked the screws with blue overnite, installed them, Started the engine, ran it on the ground a bit, shut it off, and was missing one screw. Pete's cut their screw holes a bit to large if you ask me.

Synergy...... How bout sharing your technique for getting 400 flights without applying anything to secure the screws?

I currently have four of the TBM/ Pete’s model spinners and two of the Esprit models. I have had no trouble keeping screws in place. No Loctite ever required, just tighten and run. It may be your getting some excessive vibration that’s knocking them loose.
Now if someone could just design a single bolt carbon spinner.

Woops,
Forgot, make that three of the TBM spinners. My Ultimate spinner "came loose" after it shed its wings and hit the ground at about 70 mph!

I had one do that too. Dented the fiberglass spinner pretty good it did.

I like the CF spinners on the larger engines. I always use Locktite on the screws for safety, and have never had so much as one screw come loose. Also, at their feather weight, I feel that they are less of a ballance issue than aluminum. With a ballanced prop, they all run very true for me.

And I think they look good as well.

One thing though, they are fragile. I cracked one on the first trip to the field with it, when the plane apparently rolled slighty and bumped my tail gate. I CAd it and have had no problems. Just pissed me off for a brand new $65 spinner to be disfigured before it even got in the air. I am more careful with them now.

Haha... well I take an allan key.. screw the screws in tight.. give them a little extra twist for good measure and fly my ***** off Never had a problem with them backing out at all.

I got mine today. They were out of the 3.5 so I went with the 4. Looks pretty nice, but its big. Anybody ever painted one of these CF spinners or see a problem with that?

I have allens in mine as well, seems with an allen you could crank down pretty good....enough probably to crack the spinner in fact...might be the difference

Carbon fiber can be painted just fine 3D.
•Wet sand lightly with 600 grit and soapy water to a dull finish.
•Light coat with primer.
•Sand again (lightly).
•Light coat of color (maybe two).
There most likely will be some chipping/cracking around the screw holes though.
I’ve used Ultracote paint (white) with good results.

I've used dope on a fiberglass version. Takes a about as much sanding and cleaning prep and you don't get to use primer. The type of paint used doesn't matter nearly as much as breaking the gloss by sanding, giving the paint something to bond with, and cleaning any oils or release agents from the spinner prior to painting. Any composite spinner should be expected to have some residual release agents still in place so cleaning with alcohol before and after sanding along with soap and water after sanding after is a good idea.

A 3-1/2 or 4 inch spinner looks best on a 30% Aviation Models Yak. You can get both at: www.valleyviewrc.com

TLT-Aviation