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Saber spacer

acropilotbret

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That's only a 1" most folks want these for the Wolf Cowl mod. You will need a 2 1/4 for that. But if you're in need of a 1" prop extension there you go.
 

acropilotbret

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Really? Why is the stock pitts cowl any different when using fixed pitch metal prop. This is a prop extension not a crush plate. The crush plate on my Twisted Composites is definitely not 1" thick more like 3/8" at the most. I just looked at it again and it has lugs on the front so it's prop spacer (back side of prop).
 
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acropilotbret

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Huh still dont get why a stock nose bowl needs a 1" spacer between the flange and aft prop face. Its not called out in the plans. I dont see why the catto would need a spacer and not a sensenich. On a stock pitts setup. I understand the crush plate though.
 

Neil

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I think the Catto prop may need a 7" driving disc and the 1" spacer is the shortest way to achieve this.
 

chef

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I talked to Saber when I was messing around with my prop install. His recommendation was ANYBODY using a wood/composite prop should use a 7" backing plate and crush plate. They have different thickness for your application. Beautiful workmanship. Guy on field with an 0-360 RV has a Catto on it....he was told same thing from Catto.


Clemens
 

acropilotbret

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The 76" sensenich has a 1" spacer "built in".

I don't follow what you're trying to say. My Twisted Composites (molded from a Sensenich 76X62) prop and every Sensenich prop I have owned the root trailing edge of the blade came all the way back to the same surface aft prop face offering no "space" or more room for the cowl. How does the rear face of the Catto look. I get it if people want to add more bearing surface to the flange that makes sense but spacing it farther way from the crank flange to offer more space for the cowl doesn't make sense. At least on the stock S-1S cowl. Can someone post a photo of the Catto rear face.

DSC00375a.jpg
 
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biplanebob

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Sensenich metal props do not have a spacer "built in"

Spacers are an option, thickness depending on the aircraft installation.

They are attached to the prop with two press-fit 1/2" dowel pins,

the thinnest Sensenich spacer is an "S5": 1 and 1/4 inch thick.

ie: a Sensenich 76EM8 has no spacer , a 76EM8S5 has a 1 and 1/4" spacer.

Bob

76 is the diameter, 8 is the bolt diameter in 1/16th inches, S designates spacer, followed by spacer length in 1/4 " increments
 
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Neil

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Sensenich recommends any wood prop installation over 150hp have an adapter with a 7" dia. foot print and a 7" crush plate. I'm pretty sure Catto is the same.
 

acropilotbret

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Neil, I agree with you but the above statement was it was needed for the cowl clearance on an S-1S I was just wondering how that could be. I think bob provided some insight there with dowel pin extensions but the Stock Pitts doesn't have that (76EM8-056 is the stock prop) I agree it is a good idea to add a 7" backing plate to create a larger bearing surface behind a wood or composite prop.
 

Neil

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Bret, I don't think it is necessary for cowl clearance either, but it is required to mount the Catto to a 180hp.
 

biplanebob

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acropilotbret,

your photo appears to be a Sensenich 76EM8-0-xx, the ( XX ) is the pitch number.

The spacer dowel pins, if used, are at the 12 and 6 o'clock positions with the prop blades viewed in the horizontal position.

Old production props were not drilled for pins unless needed, current production ; all are drilled for pins.

Bob
 

Morphewb

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Bret, it's basically for the spinner/prop fit for a particular airframe engine combo. That's exactly why the pressed in spacer is on the Sensenich prop we use without the spacer. Piper uses the spacer for the some of the Cherokee line. Sometimes a person can get the measurements screwed up with the cowl/spinner numbers and a small length extension is the only way to keep the spinner bulkhead from rubbing the nose bowl. I know that extensions were considered verboten years ago but with the advent of the solid flange, etc. the minor stress is absorbed with the extra metal in the shaft.....just as long as you don't get too carried away with it.
 
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hosspowerinc

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By "built in" I meant the spacer was pressed in. I had to go look at my Pitts' Sensenich and it indeed does not have a spacer. I must be getting it confused with a Super Cub we recently recovered. I have sold my Catto but Im fairly certain the hub was 4" thick. These are the specs on the required spacer and crush plate--

Prop Extension 1" long 7" diameter,

6-hole, SAE-2L Crush plate 7" diameter x 1/2" thick, 1/2" holes

SAE-2 F-911 bolts, 1/2-20 prop-to-exten, LONG thread, drilled head, length

I did consult with Saber and Catto about using a 3/8" crush plate to use the Wolf spinner and both said it was OK. Tony offers two different bulkheads for the 14" spinner but not one specific for the Catto.
 

acropilotbret

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Copy All. Thanks for the clarification I thought for a minute I was going nuts (turns out not quite yet but i'm close I guess children and building ailerons will do that to you). I think we are all on the same page now.
 

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