T

TShort

Well Known Member
What is an extended hub propeller?
Showplanes.com has a new cowl for the -8 ... I'm wondering if this means I need an extension on the prop to use this cowl. That is the main reason I'm leaning away from the SJ cowl.
For example, are the MT or aerocomposites props "extended hub"?

Thanks
Thomas
Back from OSH already ... 2.5 days is not even close to long enough! :(
 
There is a hartzell with the longer hub, Vans use to sell it for the O-320, but because it is heavy it reduces your acro capability.

Aerocomposite will build you a prop with a custom length hub, and it is a little lighter than the hartzell, so you may have less of the acro restriction.

Whirlwind will sell you an extended version of the 151, which weighs less than a Sensenich (29LBS).
 
WW151 EH and SJ Cowl

I have a WW151 extended hub with a SJ cowl. If you use this set up, the rocker box covers will rub the cowl. It is still not long enough.
 
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As I understand it, part of the reason there was no acro allowed with the extended hub hartzell was because it extends the arm of the huge spinning disc 4" out from the crank flange. This causes more gyroscopic induced stresses on the both the crank flange and the hub itself.

With the Whirlwind prop, replacing that big metal disc with a composite one really would alleviate that problem to a great extent.
 
No acro allowed??

gee I hope not cus I'm gonna break the nose of the crank off!

More seriously, in my research most everyone who knows more than me says they would have no problem with a CS Hartzell on a 2.25 prop extension doing standard aerobatics.

I.e rolls loops etc. Sure pulling 6 G's is probably not wise but unless your going for the red Bull series the small extension will make some difference but not enough to stop the enjoyment.

Now George will wax lyrical about the extension being an unknown quantity. I certainly can't argue that but apparently the Sabre prop extension has never suffered a failure.

Another thing, the SJ cowl is meant to use the extended hub prop (or a Compact hub plus a 2.625" extension). I don't know for sure but arnt there a number of Rockets out the there with extended hub Hartzells? I bet those guys don't fly straight and level.

Frank

P.s i own a Yahoo group dedicated to the James cowl.
 
I emailed Aerocomposites today ... they custom machine the hub to fit specifically for the SJ cowl with no additional charge and there are no aerobatic or other restrictions on the use of the prop.
Now, if only it weren't over 10,000$ !!! :(

T.
 
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