Hartzell Composite Blade Clearance - help!

[Sig600]

Originally Posted by DanH

If you elect to mod the cowl, it will be easy to move the cowl rearward and extend the section behind the spinner.

If the cowl hasn't even been top fitted yet, do we really know there is a problem?

Seems like getting the prop on, then top fitting the cowl to generate the clearance is the easiest option at this point. I would only start looking at cutting/modding the cowl only after it's known that proper fit will generate clearance issues.

[Doug94]

Bill,

The rotation of the prop blades is most easily accomplished with the air presure method. Disconnect the oil line from the behind the prop and just use nominal air pressure. Its a "feel-thing" and you can rotate the blade ever so slowly and hold it in position. I used a blowgun connector - without the long thin tube and just put regular plastic hose over the end and the other end over the oil fitting....Very easy.

As far as the inlet rings they mount inside the SJ Cowl. Some guys mount them outside the cowling resting the cowl in the inlet ring groove. Doesnt work that way.

finally (I have a older paddle blade style Hartzell CS prop) I used a Sabre manufacturing 4" prop spacer.

Good luck. D

[tkatc]

Originally Posted by tadsargent

Bill, you have made the best choice for a propeller.

Out team just partnered with Hartzell installed these props on all of our planes, they are fantastic

So I am wondering if you are endorsing the product BECAUSE they are a sponsor or because you truly think its the best prop available for the RV series??

[BillL]

Originally Posted by Sig600

If the cowl hasn't even been top fitted yet, do we really know there is a problem?

Seems like getting the prop on, then top fitting the cowl to generate the clearance is the easiest option at this point. I would only start looking at cutting/modding the cowl only after it's known that proper fit will generate clearance issues.

Yes, there is definitely a clearance issue. I rechecked and it is the the range of 3/8 to 1/2" that the cowl cooling inlet has to move back. That is "measured" with 1/4" gap already at the spinner. More fitting won't change these dimensions, but your point is well taken. Little differences add up.

Hydroguy2 (thanks) noted to set the fore/aft location of the cowl based on the clearance needed, not by the spinner. That sound like a good course of action. I can check for potential lower cowl clearances in the process. Then, if there is a gap to be addressed at the back of the spinner then so be it. I want to make some kind of cowl to prop shaft seal like DanH to prevent lower cowl from air leaking out, but the 2.5" spacer won't allow me to copy Dan's elegant creation. That will be a later project.

Thanks Doug94, I will provide air pressure via that port to facilitate blade rotation. It gives me a good reason to remove that crank plug now before it is forgotten. Working solo, maybe a pressure regulator will help the process and leave me two hands.

[Tom Martin]

The blades are easily turned by hand if you make yourself a bit of a lever. Here is the method I use, I am sure that someone will come forth with something more elegant! Wrap the blade with some foam, about 18" from the hub. Now take two pieces of 1 by 2" pine three feet long. Place them on the foam, on the flat part of the blade one on each side. Take your handy roll of duck tape and firmly tape the ends of the wooden pieces together. Now you will be able to easily rotate the blades with both hands and hold it in one hand to check clearances with the air inlets. If your foam is on the widest part of the prop blade then you can slide the "tool" off the prop, with the foam trapped between the wooden strips, and slide it on again any time you need to check something.

[strahler13]

Originally Posted by tkatc

So I am wondering if you are endorsing the product BECAUSE they are a sponsor or because you truly think its the best prop available for the RV series??

TK, watch out. Put on your asbestos.

Mark

[6 Gun]

Im running SJ with BA and 2.5 spacer my rings are 1/4 inch in front of cowling Im sure you could mount them flush but it would be easy to take a little off the back but it gets tight around the front two cylinders on the edge of the plenum get the plenum close as you can in front,its no problem in the rear for clearance I had to modify the plenum to get clearance in front . Good Luck.
Bob

[BillL]

I made an adapter from steel bar stock, tapped a hole to cover the oil outlet at the governor pad and piped air to it through a small regulator. No fittings removed from the engine, and it is easily controllable. 30 psi yields full pitch.

The crank plug was a piece of cake. I predrilled a dimple with a 3/16" bit, blew the chips away, then took a SnapOn awl and the hole was punched easily. It would not have been easy without the predrilled dimple. Then threaded a slide hammer screwed in there, a few bangs later it was done.

Now for measurements. I have the standard prop hub, and using the mounting face as the datum, here are the axial dimensions:

to back of spinner - 1.60 inches.
to prop blade at fine pitch = 2.18"
to prop blade at coarse = 1.00"
This is at approximately 17" radius of the blade.

I had a nice conversation with Will James and he was not aware of this prop clearance issue. I would expect he might make a cowl for it if there is a market. I will be moving the entire cowl back for 3/8" prop clearance at full pitch, and then rebuild the leading face cowl face to restore the 1/4" behind the spinner. The standard SJ cowl, makes the cooling inlets and the spinner ring in the same plane.

I was going to make a cowl-to-crank seal like DanH, but with this 2.5" extension, a fresh design will be needed.

[BillL]

Time marches on - - -

The cowl is fitted and SkyBolts installed. The cooling rings have been cast in place. The cowling faces at the cooling intake were not exactly square, so I sanded them flat to ensure the rings would be square when glassed in. It was successful. The rings protrude about .050" with some cardboard spacers.

Before getting too deep this is the check of the prop clearance at full pitch. I am satisfied that this 1/2" will be fine. The LHS, as mentioned above, is greater than this, as is the engine air inlet.


As suggested earlier in this thread, the cowling was placed for prop clearance and then the spinner ring will have to be extended. That is still TBD. Here is an idea of where it has ended up. Just over an inch from the spinner.


That is all for now, hopefully it won't be so long till the FWF is done and that pict can wrap this up.

[edsong]

My Hartzell prop clears the Van's cowl by 3/8 inch. 60 hrs and no problems.