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Thread: GSC props

  1. #1

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    Default GSC props

    Hi Guys
    are GSC props difficult and time consuming to set up, or is it just ME.The one that came with the plane a 66 inch LH was out of track up to quater inch,it had been like that from day one(1992).Letters went back and forth from the builder &GSC,it was never sorted.I was given a 68inch to try,it had been parked outside for few years and not used for last 6 years.Re furbished it but tracking is out on this one too,not as bad(3/16) .Bit the bullet and bought one from a dealer 300 miles away (thats along way in england) its as good as new ,guess what,one blade 1/4 inch outany of you guys had same problem,or know where Im going wrong apart from useing wood props!!!

  2. #2
    Senior Member t j's Avatar
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    Default Re: GSC props

    After setting the pitch of the blades did you torque the bolts down in the proper sequence, and not the 100 inch pounds all at once. Work up to it gradually.

    Bolts through the blade roots first, the other three main flange bolts next, then the outer 6 bolts. All in a crisscross pattern.

    Number the bolt heads 1 through 12 with a felt pen so as to not get confused. Snug 1 through 12 with a box end wrench, then 1 through 12 to 50 inch pounds, then 1 through 12 to 70 inch pounds then 85 then 95 then 100. Thats what I did when I had a GSC prop anyhow. Tracking was perfect.

    After you finish torquing there should still be a gap between the hub halves. If not, the blades were over torqued at some time in their life and are no good.
    Tom Jones
    Classic 4 builder

  3. #3
    Administrator DesertFox4's Avatar
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    Default Re: GSC props

    Fred, purchase an Ivo ground adjustable prop. Takes all of 20 seconds to change pitch for climb or cruise or somewhere in between and never have the blades out of "track". No loosening of bolts to change pitch and then hoping you got them torqued correctly and in the correct sequence.
    Hang the GSC on your wall as nice looking art work. That's where I put my GSC years ago and that's where it will stay. You'll spend much more time flying and enjoying your Kitfox and no time fiddling with out of adjustment blades, protractors, bolt tightening sequences, re-machining hubs, timed out blades, moisture damage ect. The Ivo is much smoother and more durable and your performance will improve.



    DesertFox4
    Admin.
    7 Super Sport
    912 ULS Tri-gear


  4. #4

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    Default Re: GSC props

    Hi Steve & Tom
    thanks for your replies,I would like to go along with your advice Steve,but I will have to percivere with what I have for now.I was not as particular as yourself Tom as there was no instructions with props but did use cross pattern,changed blades around,ect,ect,ect.Its not the end of the world,and summer is nearly upon us

  5. #5
    Senior Member Mnflyer's Avatar
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    Default Re: GSC props

    Hi Fred have you tried shimming the prop to engine hub to bring the track in line? I've shimmed a number of different props to get them in line.
    GB
    Flying a HKS Kitfox III and a Champ

  6. #6

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    Default Re: GSC props

    Hi MNFlyer
    yes, I shimmed the one,it had been out of track since new,that came on the Fox.Unfortunatly one blade got broken after EFATO,not a great deal of damage,it was soon fixed .Will sort it(hopefully) at weekend,should have plenty time,bad forecast for bank holiday weekend

  7. #7

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    Thumbs up Re: GSC props

    Hi Gary shimming was the only way to corect tracking with this prop,there is no way to put one blade 1/4 inch out (or back in line)by tightening with any pattern,spent six hours trying

  8. #8

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    Default Re: GSC props

    I'd have to say I disagree that wooden props are an all around bad choice. Many variables exist and there are applications where they are still safe. I agree however that they are more maintenance intensive. My 3 bladed wooden GSC has served me well on my Model II (582) for over 20 years now. I re-torque the bolts every 10 hours or so just to be safe and they do loosen a little but nothing's come off yet and I safety wire the bolt heads.

    GSC has been very prompt and helpful with scheduled inspections, repair, and replacement of blades. Their prices are reasonable and I have to say that the wooden blades look really sharp too.

    I seem to recall an article written by Dan Denney back in the early 90's when I built mine explaining why he chose the 3-bladed GSC. I suspect some of it had to do with the lack of other choices at the time, but he also had done some testing which showed that the wood absorbed 2-stroke pulses better than composite and was less likely to set up phased vibration modes at certain rpm's than the stiffer carbon fiber.

    Here's a kind of cute article without a lot of hard data but still interesting with iron clad references.

    http://www.airspacemag.com/how-thing...good_wood.html

    Chris

  9. #9

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    Default Re: GSC props

    Thanks for interesting article and your opinion Chris.I too like the look of wooden props,and we have to give credit to Dan, as he was the daddy after all said and done.Hearing more good about IVOprops I will have to try one , and hope it is not a costly mistake

  10. #10
    Senior Member jtpitkin06's Avatar
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    Default Re: GSC props

    I've sat back and watched this thread unfold.

    If I may, I will offer my opinion on the tracking issue posted at the beginning of the thread. When you tried different props and got nearly the same tracking error it appears to me that the hub is not running true. I did not notice anyone suggest you put a dial indicator on the hub and check for hub run-out or a bent crankshaft.

    If you had a genuine prop problem, it could be identified by marking the blades and repositioning the prop on the hub 180 degrees. If it were a prop problem the tracking error should follow the individual blade. This test was not mentioned in the posts.

    If the hub is identified as out of true but withing limits, then shims may be in order.

    Now, the other issue of a wood prop... To suggest that wood props are outdated or not as safe as other materials is simply not true. Pointing to selected reports of prop failures without supporting data is nothing more than idle hangar talk. All types of props can and have failed. Just as all types of props can have decades of trouble free service life.


    I witnessed a failure during takeoff of a McCauley Prop on a Cessna 210. The prop was new with less than five hours on it. Even so, I'm not about to state the metal props are not safe. The evidence doesn't support such blanket statements.

    On the other end of the scale, I have friends flying behind wood props on the KR and Sonex turning RPM over 4500 even though they could easily afford props made with exotic materials. They have over 500 hours on each of them and they look and perform as new.

    Aircraft manufacturers don't use many wood props these days because of economics. High quality wood props are usually more expensive than metal or composites. Contact Sensenich to inquire about the reliability of their wood props vs. other materials.

    Prop manufacturers are very skilled at matching props to engines. They can tell you what they have tested and what they do, or do not, recommend for your application.

    My suggestion is to talk directly with the prop manufacturer to answer any questions before you purchase another prop. The one you have now may actually be the best choice for your engine. They can also discuss the tracking issue and recommend appropriate actions.

    John Pitkin
    Greenville, Texas

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