Spinner

The spinner is not absolutely necessary. The spinner contributes to aerodynamics. you will lose some efficiency and fly slower, but the best way to find out is to just try it. 99% chance it will fly just fine.

I say 100% chance of OK and you likely will not be able to detect any speed drop.

Lee

"Vance" wrote

I have flown glow fuel planes without spinners, also. I even use electric starters with the rubber insert flipped around the other way. The prop nut centers the starter insert on the engine shaft. I .could not tell any difference in the performance of the plane.

Depending on the weight of the spinner it could effect the balance to leave it off. Not much, but the plane may be more pitch sensitive (need less up and down control to manuver). I would just give it a try. Bob

Spinners:

- Hamper cooling of motor

- Cause imbalance

- Add weight

- Add rotational mass (wears bearings during violent 3D maneouvres)

On my SkyArtec Cessna 182 I use a prop saver and no UC. (bellylandings on grass) It looks ugly, but the prop lives forever and motor axis never bends.

not always. True, it blocks airflow over electric motors. But air flows just fine over the cylinder of my Magnum .91 four stroke in my Super Skybolt. This plane looks stupid without a spinner

That's why you balance the spinner just as religously as your props. You do balance your props don't you?

very little. Of course i n a park flyer, that 1/2 ounce or less might make a bigger difference.

If removing the spinner is enough to effect the balance to that degree, just glue a piece of a popsicle stick to the front of the plane to add the weight in again.

True - "Looks" can be very important. I used to own a 60 size Hotts that would be visually unbearable without spinner. (some may argue that it was unbearable *with* spinner as well :-)

Spinners are some harder to balance - I had a few that would change form while turning fast and cause imbalance whereas statically it would be OK, or spinners that are 0.1mm out of centre alignment after tightening the nut etc. etc.

I guess spinners are feminine: some look good, but hard to handle right.

If in any way defendable aesthetically - I avoid spinners. (and my planes are ugly anyway - which cause the ground to repel them)

It typically won't affect anything on a small park flyer - it can be a problem on larger planes. If the spinner is one of those rubber push- ons from GWS, it will probably have little or no affect. Having said that -

Airflow changes are minimal unless it's a large diameter spinner. It can block some airflow into a cowl, reducing cooling but it can also allow a higher airspeed because of improved aerodynamics.

It can have an affect on the CG location, I have planes that needed the CG moved forward so I added a heavy spinner. It's out in front as far as you can get so a small amount of weight can make a big diff in the CG location.

Richard

Safety.

If you are unfortunate enough to hit a child, then you will do less harm if you have a spinner fitted rather than just a prop-nut.

Also check your insurance - you might find that you are not covered in such an event if you don't have a spinner.

You might be okay with a domed prop nut.

Cheers,

Nigel

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"Nigel Heather the-heathers.co.uk>" Safety.

I've always been told one of the most important reasons to use a spinner on a park flyer is safety.

Good flying, desmobob

And you can sharpen them.

-- Ray

On Mon, 13 Jul 2009 22:11:55 +0100, "Nigel Heather the-heathers.co.uk>" Safety.

Depends on the spinner - I have seen some fierce metallic pointy ones. Rather would be hit by the nut.

I am fully insured. My insurence company does not have a clue what a spinner is, and expect I use my brain (or whatever passes for that in my case) to avoid harm. (I am not living in the USA remember..)

Not sure what constitutes a "park flyer"; if it is a smallish foamy, a prop saver would be way safer - as nothing pointy is actually portruding past the propeller.

In larger models, a plastic "blunt" shaped plastic spinner with crumple zone may add safety indeed. Though a 60 size 3 KG model with

A 600gr foamy however..

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I suspect Nigel was thinking of the GWS-style park flyer gearbox, which has a very long 3mm shaft that extends about an inch beyond the prop. With sharpening this would make a nice spear point; as it is it'd hurt a lot more than the GWS-style spinner if it hit.

More normal propeller attachment arrangements are probably no better or worse than a spinner.

My Artec Cessna had the same long shaft. With the same dangers / bending risks.

So I swapped it out for a prop saver - now the axis is very short, and any bending action is taken up by the saver rubber band. Does not look all that well, but is bullit proof.