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Spinners for brushless.

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Foxfan21/06/2019 20:09:11
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928 forum posts
7 photos

Hi all,

I am making my Skystreak 32 from foam and am wondering what to do about a spinner. It requires a lovely long 1 1/2" diameter one, preferably in aluminium and such are available, but...how do we fit one to a skinny little brushless shaft (2 point something in my case)? I can make an adaptor if necessary as I have a lathe.

 

 

Thanks,

Martin

Edited By Foxfan on 21/06/2019 20:10:05

Allan Bennett21/06/2019 21:17:37
1651 forum posts
49 photos

Is your motor shaft threaded, or plain? If the latter, you'll surely be using some kind of prop adapter which will have a larger-diameter thread for mounting the prop.

Foxfan21/06/2019 22:27:16
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928 forum posts
7 photos

Allan, my motor shaft is plain. I haven't yet got a prop driver for it. I was given a prop recently, but haven't yet installed it. Are you saying that a conventional spinner back plate can be fitted to a brushless prop adaptor? Sorry to be dim, but I have no idea of electric propulsion at all!

Martin

Dickw22/06/2019 09:51:54
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657 forum posts
93 photos

Martin

Once you fit a prop driver something like this one to your motor then fitting a prop and spinner effectively becomes the same as fitting it on an IC engine.

Dick

Foxfan22/06/2019 10:03:53
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928 forum posts
7 photos

Dick, that's very useful info. Many thanks.

Martin

Foxfan22/06/2019 10:35:40
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928 forum posts
7 photos

Dick, it seems that my motor shafts are both 3mm, but all I see listed are 3.2mm diameter. Is that a normal tolerance figure?

Martin

Dickw22/06/2019 10:49:27
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657 forum posts
93 photos

I believe some manufacturers and retailers are a bit variable in their understanding of "3mm", and the tolerance I would find acceptable does to some extent depend on the power/rpm expected.

Have you tried ebay as their are many offerings around the 3mm mark - 3, 3.17, and 3.2 being common variations.

Dick

Foxfan22/06/2019 12:11:54
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928 forum posts
7 photos

Dick, as I expected. 3.1 being 1/8th" of course. I'll have a gander. I don't suppose they do a prop saver WITH a spinner adaptor do they? I wouldn't know what they'd call it.

Martin

Caveman22/06/2019 21:41:17
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285 forum posts
241 photos

Foxfan, if your shaft is 3mm then you really need a 3mm prop adaptor. A 3.2mm / 3.17mm / 1/8" one will not seat correctly on a 3mm shaft.

A 3mm adaptor is available here **LINK**

A spinner can then be mounted as per an IC engine.

GDB

Foxfan22/06/2019 22:52:56
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928 forum posts
7 photos

Splendid, thanks for the link, Caveman. I shall get me one of those (two actually).

I don't suppose you can get a prop saver with an adaptor can you? I can't see what would stop the prop breaking every time the aircraft lands if it doesn't have landing gear.

Martin

Caveman22/06/2019 23:05:14
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285 forum posts
241 photos

Here you go **LINK**

GDB

PS While you're buying you should buy a few extra O rings smiley

Foxfan22/06/2019 23:09:34
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928 forum posts
7 photos

But can that be used WITH the prop adaptor/spinner holder you linked to before?

Martin

PatMc22/06/2019 23:45:34
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4379 forum posts
524 photos

The prop saver linked fits straight onto the 3mm shaft it would be instead of the adaptor. I don't think you'd be able to use a spinner with the prop saver. Perhaps a folding prop would suit you better, spinners for them here. There may be more spinners on the Robot birds site [The owners of BRC].

Foxfan22/06/2019 23:59:45
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928 forum posts
7 photos

I quite like the idea of the folding prop. It's either that or som kind of landing gear, but how to fit landing gear strongly to a foam structure?

Martin

Dickw23/06/2019 10:19:59
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657 forum posts
93 photos

It's called a prop saver, but is just as useful for avoiding a bent shaft.

I have often used folding props as they rarely break, and also reduce the bending load on the shaft during landings without an U/C.

Another option for reducing the chance of a bent shaft is to fit the spinner as close as you can to fuselage without actually causing binding.

An IC prop would be stronger and less likely to break, particularly if the ESC brake function is used.

Lots of options to play with smiley.

Dick

Foxfan23/06/2019 10:30:19
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928 forum posts
7 photos

Oh dear, so much to learn! I didn't realise ESCs had any functions except fast and slow and perhaps backuds on a boat or car. Brakes? How does that work? Does that mean you can get the motor to stop with the prop athwartships? If so, will it always do that? And what about the windmilling tendency?

Martin

Denis Watkins23/06/2019 10:50:37
4321 forum posts
104 photos

In the olden days Fox, we just fitted one shaped u/c wire down, longer than the prop, even without a wheel

Just to save the blade

You can barely see this in the air

Foxfan23/06/2019 10:53:51
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928 forum posts
7 photos

Interesting. I like the simplicity, but didn't they have a tendency to dig in? Or was there an optimal shape and angle for it?

Cheers,

Martin

Dickw23/06/2019 10:54:35
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657 forum posts
93 photos

Most ESCs offer an optional brake function that just short circuits the motor windings and slows the motor down, usually to the point of stopping rotation. Unfortunately you can't pick the point at which it stops rotating, however the prop can still be pushed round a bit as you touch down.

It is best to use the brake option when a folding prop is fitted, otherwise the prop will just jkeep spinning (windmilling) and not fold.

Dick

Edited By Dickw on 23/06/2019 10:56:40

Foxfan23/06/2019 10:56:23
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928 forum posts
7 photos

Ah, doesn't sound that helpful, then. Maybe the wire trick will work.

Martin

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