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-   -   saito 100 Prop nut or spinner (http://www.rcuniverse.com/forum/glow-engines-114/9612443-saito-100-prop-nut-spinner.html)

shaggy48 03-25-2010 09:29 PM

saito 100 Prop nut or spinner
 
Partially broke in a Saito 100 today. I intended to put a gallon through it but the weather got nasty real fast and I had to quit and come in out of the cold and wind. Only put about 3 tanks through it, and just under the recommended 40 minutes of break-in saito recommends.
What a sweet running engine, and very easy to start. Of course I haven't started leaning it out yet so that could change. Anyway, I need to decided on either a spinner or prop nut. I've been hand starting it today and felt pretty safe doing so but I don't want to push my luck every time I start it. So I need to be able to use my electric starter. What's the general consensus to do? A spinner? or one of those prop nuts. Never used a prop nut with an electric starter before. The prop I've got on there now is 14 X 8 Zinger so my plastic 2 1/4 spinner wouldn't fit. (prop too big for the slots). I also didn't want to add a lot of weight either. The prop nuts I've seen are pretty heavy. Not that I"m overly concerned about the weight at the moment. I haven't even put the engine on a plane yet. Did the break-in on a quickly made break-in stand.

Appreciate any advice.
Shaggy.


JPMacG 03-25-2010 09:53 PM

RE: saito 100 Prop nut or spinner
 
I use prop nuts on all my engines, including my Saito 72 and 100. I like the Dubro prop nuts the best. They have a shape that engages well with the cone on my starter, and they are very nicely machined, and have a circular groove in the back for weight reduction. On 4-strokes I use a large thin jam nut behind the prop nut. Harry Higley makes large thin nuts that work well for this purpose. Both the prop nuts and the jam nuts are aluminum.

There seems to be some controversy regarding the use of plastic spinners on 4-strokes. Some say no problem, others say don't do it.

BTW, Dubro makes brass (nickel plated) prop nuts as well. You don't want these if you are concerned about weight. Get the aluminum ones. They come in bare aluminum and anodized aluminum in several colors.

MinnFlyer 03-26-2010 06:09 AM

RE: saito 100 Prop nut or spinner
 
The prop holes in spinners are made small to fit small props. It's up to YOU to enlarge the holes for larger props. So it's not that your spinner "Doesn't fit" - it's more a case of, "You haven't cut it to fit yet"

I have no problem using plastic spinners on 4-strokes. I've been doing it for about 20 years with no problem.

BUT...

When you enlarge the holes, use a dremel tool or round file. You don't want to leave any sharp edges where a crack could start (This goes for 2-strokes as well as 4-strokes).

ThumbSkull 03-26-2010 06:20 AM

RE: saito 100 Prop nut or spinner
 
I think it depends on the airframe. No need for a spinner ever on a profile. The purpose of a spinner is to create a nice transition to the fuselage.
If it's on a profile or a stick then just the nut. If it's a pattern or sleek sport plane then a spinner is in order.

Cherokee Flyer 03-26-2010 07:32 AM

RE: saito 100 Prop nut or spinner
 
If you think it runs nice now, put a Turboheader from RC Specialties on it. Also try starting it by flipping it backward; that way you make the enigne start its self and don't have to push it through compression.

L.

ArcticCatRider 03-26-2010 09:08 AM

RE: saito 100 Prop nut or spinner
 
I don't really like to look of prop hubs on anything but old timers. I like spinners.

But with how 4 strokes back fire, you're going to need to use a jam nut. A Harry Higley jam nut..which is about a 1" nut, or 7/8ths" or whatever...then you're regular nut. Or your spinner nut if you're using an aluminum spinner.

I like aluminum spinners...but they are expensive. And a good backfire from a 4 stroke will ruin an aluminum spinner instantly, reinforcing the importance of a jam nut

shaggy48 03-26-2010 10:13 AM

RE: saito 100 Prop nut or spinner
 
Well the plane is a yak so I don't think the spinner will look right. But in the interest of safety and ease of starting I was thinking a spinner would be the best choice in that respect. But if I can still use my electric starter with a prop nut I"d go that way instead. The Saito comes with a jam nut that goes on after the prop nut. If I decide to use a prop nut doesn't that defeat the purpose of the jam nut? Don't think I can use the jam nut and the prop nut right? Or will the prop nut suffice? Doesn't the prop nut go on right after the prop washer. i.e. you don't use the prop nut or jam nut?

Yeah I thought about cutting out the slot in the spinner too but the one I have I'd have to take out some of what the screw goes into that holds the back plate on. Decided it wasn't worth it to ruin the spinner, since I may not keep it on this plane anyway.

ArcticCatRider 03-26-2010 10:24 AM

RE: saito 100 Prop nut or spinner
 
1 Attachment(s)
You can use a Harry Higley jam nut, then the prop hub.

http://www3.towerhobbies.com/cgi-bin...?&I=LXL742&P=0

http://www3.towerhobbies.com/cgi-bin...?&I=LXL745&P=0

Thread the thin nut on first, tighten down with an box or crescent wrench...then thread the hub on. Some have a hex, some have a hole that you'll use with an allen wrench, or whatever you can fit in there to tighten down.

With this set up, there's no need for the stock washer or any of the nuts that came with the motor. I'm pretty sure the Saito 1.00 is an 8mm thread. I'd double check before you buy unless someone here chimes in who's certain what it is

blw 03-26-2010 10:30 AM

RE: saito 100 Prop nut or spinner
 
1 Attachment(s)

Quote:

ORIGINAL: ThumbSkull

The purpose of a spinner is to create a nice transition to the fuselage.
Depending on your sources, spinners are considered to give 5-7% reduction in total drag.

Great Planes has a pretty good selection of plastic spinners with aluminum back plates. I've had a few not-so-violent backfires without problems using these. Like MinnFlyer pointed out- he hasn't had problems in 20 years. I just get those types now out of habit and a bit of extra insurance.

This is a good quality prop 4 size metric prop reamer for your Saito: http://www3.towerhobbies.com/cgi-bin...&I=LXK248&P=ML


shaggy48 03-26-2010 01:33 PM

RE: saito 100 Prop nut or spinner
 
Ok thanks guys. I'll double check the threads and get a Harry Higley jam nut and go with a prop nut after that.
And thanks for the info on the prop reamer. I'll add that to my list of things to get as well. Of course I just used a drill going carefully up in size until I got the hole right. No splitting and just as well balanced, but the reamer sure is better. I've got an old one but of course its only two sizes, which are too big and too small.

Boy at this rate it'll be June before I get this plane done and airworthy Every time I find something else I need I have to order it online.
My local hobby shop is just about useless for anything I need right now. Needed some servo arms, they don't have em. Needed some 12" servo extension - no got em. A spinner or prop nut. Same thing no got em. They don't even have thin CA! If I have to wait for them to order everything I need I might as well just order it myself online. Anyone else's local hobby shop like that? No got em?

ArcticCatRider 03-26-2010 01:48 PM

RE: saito 100 Prop nut or spinner
 
I was curious so I went and looked myself about the thread. It's 8x1.25

The 1.00 is the smallest motor to use the 8 mm shaft.

A lot of hobby shops are like you describe unfortuantely. Lucky for me, living in Chicagoland I have access to some kick ass hobby shops. One is the best in the Midwest.

shaggy48 03-26-2010 02:18 PM

RE: saito 100 Prop nut or spinner
 
You are absolutely correct. Just happen to have a metric thread gauge in the garage so I checked too. Hey do you use a velocity stack and bru-line filter on your 100?


Shaggy.

ArcticCatRider 03-26-2010 02:25 PM

RE: saito 100 Prop nut or spinner
 
No I don't...I just use mine the way it is. It's on a Four Star 60 with a 14x9 and Powermaster 20/20 fuel.

It's a nice motor.

ThumbSkull 03-26-2010 02:38 PM

RE: saito 100 Prop nut or spinner
 

Quote:

ORIGINAL: blw

Quote:

ORIGINAL: ThumbSkull

The purpose of a spinner is to create a nice transition to the fuselage.
Depending on your sources, spinners are considered to give 5-7% reduction in total drag.
I think the spinner is only a benefit if the spinner meets the fuse and the flow is smooth.
If there is a large gap or the round spinner meets a square or flat fuse some number of inches away, you might actually create some drag.

MinnFlyer 03-26-2010 03:25 PM

RE: saito 100 Prop nut or spinner
 
Don't feel bad, my "local" hobby shop is 100 miles away!

blw 03-27-2010 10:32 AM

RE: saito 100 Prop nut or spinner
 
The savings are from the drag and stalling regions of the hub area where the prop is thickest. The prop may be stalling most of the time and certainly isn't producing power. Also, the shaft, nut, and crankcase face are all large drag components.

The fuselage consideration is an excellent point that many people don't think of, and has a lot to do with engine/prop performance. However, in this case of the gap I would think the drag would less.

If I had a hobby shop, I would stock those small items to get guys in my store. Getting them in the store is half the battle, right? My LHS hasn't ordered any new props in about 3 years. I think a lot of people would go there for a prop and walk out with more than that most of the time.


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