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Hartzell Composite Blade Clearance - help!

BillL

Well Known Member
The wide cord on the Hartzell composite blade results in an issue. It appears that in the low pitch mode (10deg) that the back side of the blade is 7/8" from the front of the SJ cowl. The high pitch is 27.5deg and the cord at this point is 8 inches. By calculation, going to high pitch will move the back side of that blade 1.15". Soooo, I need to create some clearance, and it may get worse with the inlet rings installed.

Options:
1. cut the cowl just behind the spinner and move everything back .6 inches.
(my favorite)

2. somehow move the cooling inlets back .6 inches.

3. extend the spinner .6 and move the entire cowl back, yes 0.6 inches.

4. Other??

What have others done to address this issue?
BTW- I have the 2.5 in extension to reduce cowl interference possibilities.
Prop%2520Clearance.%2520.JPG
 
Use some air pressure to move the blades to coarse pitch and physically check. Doing the numbers in my head I get about the same answer (a little over an inch) but this movement will be in an arc, partly aft and partly down.
 
I recall seeing something about Hartzell limiting the low pitch stop to prevent this. I would check with them first.
 
Bill.
Is the cowl top fit????

Do that first.
The rings won't go farther than the cowl fiberglass .

You can adjust the clearance between the spinner and cowl.

What I see in the pick the cowl needs to go down .25 to .50 for engine sag.
That will move it back a little.

Hope it helps.

Boomer
 
Use some air pressure to move the blades to coarse pitch and physically check. Doing the numbers in my head I get about the same answer (a little over an inch) but this movement will be in an arc, partly aft and partly down.

Bob, I was going to make a handle and twist them, but I like the air pressure idea, do I just pressurize where the oil line goes to the front of the crankcase?

I recall seeing something about Hartzell limiting the low pitch stop to prevent this. I would check with them first.

Yes, Walt, I will contact them, but heard that this was not a recommended permanent fix. I don't know why.
ref: http://www.vansairforce.com/community/showthread.php?t=51841&page=2

Bill.
Is the cowl top fit????

Do that first.
The rings won't go farther than the cowl fiberglass .

You can adjust the clearance between the spinner and cowl.

What I see in the pick the cowl needs to go down .25 to .50 for engine sag.
That will move it back a little.

Hope it helps.

Boomer

Boomer, No, the cowl is just sitting there about with a 1/4" gap from the spinner. Glad to hear the rings won't protrude more. The 1.15" is the horizontal component of travel, so with 1/4" clearance at full pitch, then I still need .6, maybe I can squeak some here and there to reduce it. I could add a 1/4" to the flat behind the spinner, too. Maybe the axis of rotation is not in the center of the cord.

The cowl fitting is next as i want to rivet the Skybolt tabs down the side of the fuse with the engine off. With many of these just supplied by Hartzell to the aerobatic team, I hoped to get some information on their solutions too. Per postings, they did limit the travel on some.
 
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If you elect to mod the cowl, it will be easy to move the cowl rearward and extend the section behind the spinner.
 
If you elect to mod the cowl, it will be easy to move the cowl rearward and extend the section behind the spinner.

gets my vote. get the correct clearance at the inlets, then moving the spinner flange forward will be the easiest fix.
 
  1. Ensure the Prop has been setup for "RVs" by Hartzell / Prop Shop i.e. limiting the Coarse Pitch Stop
  2. Certainly with us, Hartzell made sure we had the "standard (Vans) cowl"
  3. The "problem" area is RHS mainly, at the furthest outboard point of the cowl. Is the SJ cowl "wider" at the OB point (as well as further forward?)
 
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Bill, you have made the best choice for a propeller. At this stage in the process you have many options to get the spacing needed.

1. Shimm the spinner back place the maximum amount aft prior to cutting your cowl.
2. Trim for clearence on the right edge of the cowl if needed.
3. Have a friend help you twist the blade when mounted on the engine,
You neede a minimum of 3/8 twisted with 1/2 " to be optimum.
4. Some one suggested a lower pitch stop, I would not recommend this, you actuall want more pitch here.

Our team just partnered with Hartzell installed these props on all of our planes, they are fantastic
 
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Move the cowl back and leave the spinner alone. I see so many people struggle getting the cowl off and on during maintenance because they only have 1/8" or 1/4" space between the spinner and the cowl. Give yourself about 1/2" and it will make life a lot easier in the long run. The T-6 Texan II I used to fly had more than an inch!

Jerry
RV-8 N84JE
 
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.
 
Rotation of prop

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
 
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??
 
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.
 
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.
 
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Rings

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
 
More Measurements.

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.
 
Final Clearance

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.
Prop%2520Clearance.JPG


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.
Spinner%2520Clearance.JPG


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

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


Here are the reasons the advanced composite propeller is the best propeller for an RV. The simplest being weight savings, which in turn allows more fuel/baggage capacity. Second is the static thrust is greatly improved. I sense this at takeoff power settings, aerobatics and increased braking performance.
Being a composite material affords you ?some? field repair considerations.

Lastly, is my opinion, it looks fantastic.
 
Asbestos Not Required

TK, watch out. Put on your asbestos.

Mark

I know that Tad's comment was "short and sweet".
I know that Hartzell is a sponsor of Team AeroDynamix.

I **ALSO** know that Hartzell makes fine props. (Most of the props that were replaced with the Hartzell Advanced Composites model were Hartzell metal.)


I **FURTHER** know that many of the team members have waxed poetically about the "bite", the pull, the braking, the smoothness, the weight and the "beauty" of that prop.

This has been done in "closed company" (only team members around). So nobody there to impress.

Finally, although I have affiliation with the team, I do NOT fly with one of the props (wish I could!!! :) ), but I have flown on my plane, Ed Sterba, MT, Catto and metal Hartzell props. When I flew Widget's RV8 with one of these props (on an ECI 370 Stroker), it was SMOOOOOTH!!! Way smoother than my O-320 with Hartzell metal CS.

It has been implied at times before that if there is a relationship between companies and people here that a positive post or comment *may* not be as warranted. I believe that just about everyone on this forum will only say positive things that they really believe and about products that they really believe in.

Finally, finally, :), any vendor that puts their product out there for testing, evaluation, abuse by one or many probably believe that a) they have a good product and that b) microscopic exposure will make it even better.

This post is in no way meant to reflect negatively about the person to whom I am replying. Not at all. It was simply an opportunity to say something that has been on my mind for months.

James
 
I believe it's the best prop out there for the RV series. If you can afford it. Priced in line with other composite constant speeds. Faster than the typical benchmark prop, the 7497.

Oh, and completely supported for the foreseeable future. <- that bit is the most important.
 
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