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Thread: Prop choice

  1. #1
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    Default Prop choice

    Ok, all you KF guru's, I have the $64 question. I have three props in my posession that I can put on the uncompleted IV I just purchased. The GSC 3 blade, a 2-blade Warp Drive Taper tip (70"?), and a 3-blade Whirlwind of 70".
    While the Whirlwind is currently on another plane I am thinking of ordering one of the new Whirlwind 75" STOL props for that plane and if I do the 70" will be available for use.
    I think the Whirlwind is the best prop but since it may be a while before I can afford the 75" I will use either the Warp or the GSC.
    Is the Warp Drive a better performing prop than the GSC? My personal experience with this 2-blade Warp was that it had excellent climb and very good cruise numbers but it seemed to be 'harder' on the 912. It also was not nearly as smooth as the 3-blade Whirlwind that replaced it.
    I have read on here both pros and cons to the GSC but I seem to still see alot of them being used so they can't be all that bad.
    I may send the Warp back to the factory and see if it needs balancing. Or just sell it.

  2. #2
    Senior Member jiott's Avatar
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    Default Re: Prop choice

    The factory is currently installing the 3-blade Whirlwind on the SLSAs. Its a beautiful prop using the latest scimitar shape technology.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  3. #3
    Senior Member jrevens's Avatar
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    Default Re: Prop choice

    Do you know if it is the 75" one, Jim?
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
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  4. #4
    Senior Member jiott's Avatar
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    Default Re: Prop choice

    I'm pretty sure its the 70".
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  5. #5
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    Default Re: Prop choice

    Jim, I totally agree that the Whirlwind is a nice looking prop. As I stated in my original post, I already have one in 70" and it is on my RANS S7. This plane originally had the Warp 2-blade I mentioned, but at higher RPM, there was a buzz/vibration throughout the plane that I was not comfortable with. I researched props and bought the WhirlWind. I looked at the Kiev prop which looks very similar to the Whirlwind. I had read very good reports on the Kiev and was close to buying one but then I read that, occassionally, getting replacement blades could take several weeks. That is something I was not comfortable with.

    I think I will try the GSC prop before giving up on it. I do like the look of the wood prop on the Kitfox. Plane itself has a 'vintage' look and the wood prop just seems to fit.

    I don't have the money at the moment to order the 75" STOL prop but I am hoping to sell the Warp for enough to offset the cost a bit. I really liked the performance I got from it but I want to go on floats and the blades either need to have the nickle edge installed or new blades purchased.

  6. #6
    Senior Member Flybyjim's Avatar
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    Default Re: Prop choice

    I bought the Keiv 3 blade from Ted at B&B in Md. and have it on my Rans S7. I like the prop a lot, smooth no vibrations like I had on the 2 blade Sensenich ground adjustable composite prop. I had a drumming effect on the wind screen at 5200 on my rotax 100hp. I think I will try the Whirlwind on my Kitfox SS7 also due to the situation with the blade replacement.

  7. #7

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    Default Re: Prop choice

    HI Folks,
    I'm not endorsing any prop at this point, still building a Just Aircraft Superstol and have already purchased a Catto, but you may want to check out some of the threads on the Wings Forum Just Aircraft sight on prop choice. THere has been quite a bit of discussion lately. Most of you have probably heard of Steve Henry, the dead stick take-off guy, and he has tried just about all the propular props including the Whirlwind. His favorite at this time for all around performance is a Prince prop. There are a couple of other guys giving very good reports on the Prince also. Again I don't know anything about them other than reports from several people at the other site on how well they perform in takeoff and cruise. Also there is some discussion on prop choice on the "Backcountry Pilot" site in the "912 Big Bore" thread. I don't have a dog in the hunt, only submitting this as food for thought.

    Take Care,
    John

  8. #8
    Super Moderator Av8r3400's Avatar
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    Default Re: Prop choice

    Thanks for dropping by with some "out of the box" thinking.

    I, too, have been following discussions on "Wings" and "Back Country Pilots" on the topic of the newly emerging fixed pitch, high tech, props being offered by Prince and Catto.
    Av8r3400
    Kitfox Model IV
    The Mangy Fox
    912UL 105hp Zipper
    YouTube Videos

  9. #9
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    Default Re: Prop choice

    Never argue with a wife....especially when she tells you to order the new prop while it is on sale!!!! Whirlwind had a discount valid through the 2nd of Dec. and since the spousal unit was here visiting me for Thanksgiving, she TOLD me to go ahead and order it. Called WW and they had one is stock and shipped it out that day. It arrived a few days later. WOW!!! I thought my 70" WW was a nice looking prop, this new 75" is even nicer. Carbon fiber material itself can be seen through the clear coat that is on the prop. Nice white tips, and the prop looks almost like it belongs on some kind of high speed Lancair/Glasair with an IO-550!!! Couldn't believe how much bigger just 5" of blade can appear.
    I have been told size matters! I am talking props here!

    I couldn't wait for more reports on the Prince or Catto, just too impatient I guess.

    I will use the GSC (maybe) on the Kitfox for a while and then take the 70" WW off my RANS S7 and put it onto the KF. Put the 75" on the RANS since it has the Zipper motor and 29" AkBushwheels. I think the KF with the smaller tires (currently has the 21" Nancos) might be too close to the ground for the 75" prop. First thing is to get the plane flying I guess and go decide what I want to do.

  10. #10
    kitfoxnick's Avatar
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    Default Re: Prop choice

    You are probably aware of some of the GSC problems. I think many people have had good success with them. There have been some instances of them shedding blades. That's why GSC put a 5 year 500 hour TBO. I think most of the problems were from over torquing or corrosion.

    Here is a link to the Service Bulletin http://www.ultralightprops.com/bulletins/051799_sb.pdf


    May 17, 1999
    GSC SYSTEMS SERVICE BULLETIN

    AFFECTED MODELS All GSC Systems 2 and 3 blade ground adjustable
    GSC Systems has been in the business of producing quality props for over 15 years for many types of aircraft.
    Over the course of these 15 years, it is possible that the original aircraft and/or the GSC propeller may have
    changed ownership several times. During the transfer of ownership often the instructions and maintenance
    procedures of our propellers have been lost. To that end, many propellers receive incorrect maintenance.
    The most critical assembly procedures of our propellers are that the hub and root ends not be tighten past the
    recommended 100 in/lb torque specification. It is also possible that due to the over tightening of the attach
    bolts, that the space between the aluminum hub halves is no longer visible. The result of this improper assembly
    or maintenance could result in premature blade failure resulting in either injury or death.
    If you do not presently have a set of GSC assembly instructions please contact GSC Systems and one will be
    forwarded to you.
    REQUIRED SERVICE Immediate inspection
    1. Inspect to insure that a visible gap between the Aluminum hub halves is detected. If no gap is visible contact
    GSC Systems.
    2. If you are the initial and original owner of a GSC Propeller, are you certain that the hub has never been
    torqued past the 100 in/lb MAX torque specification, if not contact GSC Systems.
    3. If you are not the original owner of a GSC propeller can you be assured that the GSC propeller hub has
    never been torqued past the 100in/lb Max torque specification, if not contact GSC Systems.
    GSC SYTEMS TBO
    GSC systems have documented user times of over 1000 hours but due to the nature of the exchange and selling
    of our product we are implementing a 500 or 5 year TBO for all GSC propellers.
    If you require further information please feel free to contact GSC Systems. Our goal is to continue the supply
    of a quality and safe product.



    If it were me and I was going to use this prop I think I would put some sort of cable around the motor mount and around the firewall. If a blade departs there would be a good chance that the unbalanced prop would rip the engine off. With the cable you could keep your CG and make an emergency landing.
    Nick W
    IV 1200
    912Ul
    Warp Taper Tip

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