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Prop Spacer or Prop Extension - survey

What do you use on your airplane?

  • a short (3? or less) prop spacer

    Votes: 8 25.0%
  • a short (3? or less) prop extension

    Votes: 8 25.0%
  • a long (more than 3?) prop spacer

    Votes: 2 6.3%
  • a long (more than 3?) prop extension

    Votes: 12 37.5%
  • something else (if that?s possible)

    Votes: 2 6.3%

  • Total voters
    32

humptybump

Well Known Member
I was recently told that the long bolts required for using a 2-1/4” propeller spacer were getting hard to purchase and there are advantages to a using a prop extension. (I had no problem with a recent order of new bolds from Vans Aircraft.)

Thought I’d do two things to help those in the process of building or modifying their airplane.

First, do a quick survey. Second, give contributors an opportunity to post their opinion/experience on the subject.
 
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Oops.

If a moderator could correct the title please. It should read:

?Prop Spacer or Prop Extension - Survey?

This will help current and future readers and searches.

Thanks.
 
Using the James long cowl required a 4" extension from Saber, who also supplied the bolts. This extension does not require super long bolts. The extension bolts to the flange and the prop to the extension.
 
I was recently told that the long bolts required for using a 2-1/4? propeller spacer were getting hard to purchase and there are advantages to a using a prop extension.

Who recently told you that?

I have not heard about any difficulties.

If it were true, it would pretty much put Sensenich out the metal RV prop business because there attachment is designed around the use of long bolts.

Also, I see a negative value in using a hub style if installing a wood/composite prop. With the lighter propellers, also using a lighter extension/hub can be a detriment in regards to aircraft utility because of the negative influence on C.G. position.
 
Who recently told you that?

I have not heard about any difficulties.

If it were true, it would pretty much put Sensenich out the metal RV prop business because there attachment is designed around the use of long bolts.

Also, I see a negative value in using a hub style if installing a wood/composite prop. With the lighter propellers, also using a lighter extension/hub can be a detriment in regards to aircraft utility because of the negative influence on C.G. position.

I had to replace 3 prop bolts recently. I tried to buy them from Saber (because they were significantly cheaper,) but they were having difficulty getting the proper length from their supplier. I ended up buying them from Sensenich.
 
prop extension, from the source

Vans was very clear on this topic when I asked them very recently, as I was placing a Catto prop on an IO-320 on their cowl:

"Regardless of the engine/cowling combination the propeller extention for a fixed pitch prop will be the same 2.25"

Cheers.
 
Not Quite all...........

Vans was very clear on this topic when I asked them very recently, as I was placing a Catto prop on an IO-320 on their cowl:
"Regardless of the engine/cowling combination the propeller extention for a fixed pitch prop will be the same 2.25"
Cheers.

Fixed pitch cowlings supplied before the mid '90s all used a 4" extension.
 
No problem.

We have found no problem in getting parts. We use a 2 1/4" spacer for a Prince prop. We did buy the spacer and bolts from Saber for both the spacer to engine and the prop to spacer make-up. Van's had them as well, but we just did the old one stop shopping thing to save on shipping at the time.
Hope this helps your question. Yours, R.E.A. III # 80888
 
We have found no problem in getting parts. We use a 2 1/4" spacer for a Prince prop. We did buy the spacer and bolts from Saber for both the spacer to engine and the prop to spacer make-up.

If you have one set of bolts connecting an aluminum section to the engine flange and then a separate set of bolts from the aluminum section to the propeller, this is what I was calling an “extension”.

The spacer has thru-holes and requires bolts long enough to pass through the crush plate, propeller, spacer, and thread into the engine flange. For a 2-1/4” spacer, these bolts are typically more than 8” long.
 
If you have one set of bolts connecting an aluminum section to the engine flange and then a separate set of bolts from the aluminum section to the propeller, this is what I was calling an ?extension?.

The spacer has thru-holes and requires bolts long enough to pass through the crush plate, propeller, spacer, and thread into the engine flange. For a 2-1/4? spacer, these bolts are typically more than 8? long.

Glen, when you put a 3 1/2'" thick wood prop, a 3/4" crush-plate, spinner bulkheads, and washers into the stack-up, the bolts or long as you ask.
I would have to size them again after all these years, but they are at least 7-8 inches long. Thanks for you clearing up what an extension is.
Hope this helps, Yours, R.E.A. III # 80888
 
Update

Those long propeller bolts needed when using a 2.25" spacer are getting rare. I just received an email from Vans Aircraft - after attempting to order a replacement / that they no longer have the AN8-82. A call to Saber was answered with to switch from a spacer to an extension. Fortunately Saber can re-machine my recently purchased spacer to make it into an extension.
 
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I am actually in the process of removing a Vans 2 1/4 inch spacer with the long bolts AN7 - 8 5/16 inch long and replacing with a Saber 2 3/8 extension. My purpose is to put a 15 lb crush plate on with the new extension to allow a better CG position. All on an RV9 with 0 320 D2J with a Prince P tip composite prop. I could not find and did not really want to add that much weight with the long thru bolt and prop spacer. However that arrangement of long bolt and spacer has never had any signs of problem after 500 hours on this plane and Who knows on the RV6 that all that came off of out of Springhill TX. ( close to Mule Shoe,TX) :D

That spacer and 6 ea prop bolts will be available around July if anyone want them. Dennis
 
On the nose...

Glen,
As Mel mentioned, many early vinylester (mine included) RV4 and Six cowlings were offered in Fixed Pitch and Constant speed dimensions.
The FP cowls required a 4" Prop Shaft extension no longer offered by Vans. Now all the newer Pre-Preg cowls have the same length.

As mentioned Sam at Saber will build you either a extension or spacer and offers Grade-Eight bolts in any length you need.
CG adjustment notwithstanding, a steel spacer or crush plate as mentioned above, are options. Sam will make it as light or heavy as needed and can really help the lighter RV's adjust the CG forward.

Also, many wood props out there (Sterba, Hertzler, Catto, Performance and Props Inc) have very different hub thicknesses. A critical measurement is from the engine flange to the edge of the cowl plus, the spinner, prop and crush plate. It's important to account for the prop hub thickness.
Also, the Van's (and Catto) spinner skirt add 1" to that. So when you chat with Sam, have those numbers handy. Even after it's hung you may have to use a belt sander on the spinner skirt to fine tune the cowl to spinner skirt space.

Having hung one or two RV props over the past 25 years, Sam is the real deal.
He can machine whatever you need, even my former VW powered Sonerai sports a Saber custom extension.

He's also a neighbor.
(in TX that means within 100 miles):)

http://www.sabermfg.com/

V/R
Smokey
 
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... Sam at Saber will build you either a extension or spacer and offers Grade-Eight bolts in any length you need.

Thank Smokey.

While Saber can make both spacers and extensions, the recommendation now from Vans, Catto, and Saber is to use an extension if its an option.

As for the long bolts, Vans and Saber are both having issues with sourcing the long bolts needed by an RV when using a spacer. My recent order to Vans was canceled (by them) because they didn't have any. Saber no longer lists the long bolts needed by a modern RV using a spacer.

The above is so significant that Saber asked I ship my new 2-1/4" spacer back and they are converting it to an extension.



BTW: I did my flight training in TX. 100miles doesn't get you very far. On the flip side, long cross countries were easy to flight plan.
 
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Investigating a replacement prop for my Rv-4 'Classic' now, and came across the Whirlwind ground adjustable FP prop GA200L - they use/sell an extension that bolts to the engine flange, and then their prop bolts screw into the extension. Seems like a good solution and no long bolts neeeded. Maybe it is usable with other prop brands. I have the old spool-type 4" extension, original long cowl, 12" spinner, and would like to keep it that way if I can.
 
I am actually in the process of removing a Vans 2 1/4 inch spacer with the long bolts AN7 - 8 5/16 inch long and replacing with a Saber 2 3/8 extension. My purpose is to put a 15 lb crush plate on with the new extension to allow a better CG position. All on an RV9 with 0 320 D2J with a Prince P tip composite prop. I could not find and did not really want to add that much weight with the long thru bolt and prop spacer. However that arrangement of long bolt and spacer has never had any signs of problem after 500 hours on this plane and Who knows on the RV6 that all that came off of out of Springhill TX. ( close to Mule Shoe,TX) :D

That spacer and 6 ea prop bolts will be available around July if anyone want them. Dennis

That 2.25 prop spacer and the 6 each AN 7 prop long bolts are now available if anyone want them . Text me 7708233426 and we can agree on a price.
 
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