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Thread: Prop for rotax 100 hp?

  1. #1

    Join Date
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    Default Prop for rotax 100 hp?

    Ok, everyone's commits pointed me to purchase new engine for my modified kf5 with kf 7 upgrades. What prop is everyone using? Three blade? I am ordering my engine from John,where should I get deal on prop? What spinner, fiberglass or aluminum? Any suggestion on extras to order with my rotax? I bought the extra alternator and installation kit, I have 2 ea garmin g3x and going to use a double battery setup for my panel. I don't want vacccum, so which back up steam gauges would you suggest? Alt,a/s,back up oil/water gauges or use rotax for engine backup? Thanks for your help

  2. #2
    Senior Member kmach's Avatar
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    Default Re: Prop for rotax 100 hp?

    I think 3 blade .

    if you can afford the airmaster then it would be the one . Blades would be a personal choice.

    What does John at kitfox recommend ?
    Kevin,

    Kitfox Outback
    912 ULS
    Airmaster AP332CTFH-WWR70W
    Summit Aircraft Wheel Skis
    C-FOXW

  3. #3
    Senior Member jiott's Avatar
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    Default Re: Prop for rotax 100 hp?

    I believe 3-blade is the best way to go for smoothness and good ground clearance. Airmaster CS if you can afford it. Whirlwind 3-blade 70" GA seems to be a very popular choice right now-I have had one for 2-1/2 years and am very happy. Also I would recommend the Whirlwind carbon fiber spinner. Kitfox can sell you this package. Don't go fiberglass spinner because the back plates are not strong enough to resist slow crushing and loss of prop bolt torque.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  4. #4
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    Default Re: Prop for rotax 100 hp?

    While I have used both, and have a 2-blade for sale, I will have to agree and say the 3-blade is smoother.

    I think the 2-blade pulled better and maybe was a touch faster, but I can feel the difference in regards to it being smoother running.

    I've got two different Whirl Wind 3-blades. I will mention that the 72" one was sufficient but I wasn't happy with the fact that it started getting some pretty obviuos cracks in it with less than 20 hours on it. I contacted Whirl wind, and they said they would charge me a 'reseal/repaint' fee to have it checked and fixed. Granted I had the prop over a year (military family, so I was away from the plane for a long time) so it was out of warrantee.

    I had purchased the 75" STOP prop before I noticed the issue with the 72" otherwise, to tell the truth, I would not have purchased another prop. Just me, but I felt the 72" sure should have not had cracks in it that quickly.

    Anyone want to post pictures or see what I am refering to just PM me and I will email them to you.
    Last edited by WWhunter; 03-01-2016 at 06:19 PM.

  5. #5
    Senior Member jdmcbean's Avatar
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    Default Re: Prop for rotax 100 hp?

    70" or 75" Whirlwind 3 blade would be our recommendation. We have a Whirlwind Prop and 11" Carbon Fiber Spinner kit for the 7 firewall forward.

    I believe the cracks Hunter is referring to were gel-coat cracks.. We had some as well early on and suspected it might have been caused by a line guy getting the prop tip with the fuel hose. Regardless, we worked with Jim (Whirlwind) on a resolution and have been flying his props for several years now without issue. We never saw any issues on the 75" props since their release. We have slightly over 1000 hours on the 75" prop and much more than that on the 70".

    Warp Drive.. Is a little less expensive and a fine prop... We have many hours operating them as well.

    We like the aesthetics of the Whirlwind and felt it achieved slightly better performance in climb and about the same in cruise.

    AirMaster.. Money and Sport Pilot out of the equation.. it is the only way to go. Although heavy.. IMHO, the performance is well worth the weight penalty. They can be equipped with either the Whirlwind Blades or the Warp Drive Blades.
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    John McBean
    www.kitfoxaircraft.com
    208.337.5111

    "The Sky is not the Limit... It's a Playground"

  6. #6
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    Default Re: Prop for rotax 100 hp?

    Excellent response Mr. Mcbean! I totally concur, the WW is a very nice looking prop and I am happy with its performance. It is also much lighter than the 2-blade Warp Drive. I weighed the Warp, backing plate, spinner, hardware, and complete prop at 14.52 lbs. The 3-blade 70" Whirlwind with the same items weighed in at 8.94 lbs. The 3-blade 75" Whirlwind was closer to 11 lbs. if I remember correctly. I have the logs over in the hangar and will check them for the exact weight.

    As you state, it appears to just be gelcoat cracks, but it sure is ugly and quite disheartening to see them after spending hard earned money. They (Whirlwind) assured me it wouldn't have any affect on performance. For me, it was scary to look at and think it might be broken/cracked internally. My luck is that it would splinter in a gazillion pieces while I was flying out of my strip in the woods.

    All this may be in my head, but once a guy has been involved in any kind of accident that busts you up and leaves you immobile for nearly two years, one does tread much more lightly than before. Speaking from experience....

  7. #7
    Senior Member kmach's Avatar
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    Default Re: Prop for rotax 100 hp?

    John , do you have the weight of the 70" and 75" whirlwind 3 blade Airmaster setups including spinner ?

    What does the 75" do , compared to the 70" ?
    Kevin,

    Kitfox Outback
    912 ULS
    Airmaster AP332CTFH-WWR70W
    Summit Aircraft Wheel Skis
    C-FOXW

  8. #8
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    Default Re: Prop for rotax 100 hp?

    And just for interest, I have the 75" WW blades, Airmaster and 912is Sport - works just fine for me so far - though only 93 hrs on the clock. Yes, it was an expensive combination but I figures that I'm only going to do this once!

    cheers

    r
    Ross
    Mt Beauty, Vic
    OZ
    Sold to Richard and Scott Taubman in OZ, 2019. Kitfox SS7,Rotax 912is Sport, Airmaster CSP 75" blades.
    Landcruiser and Cub off road camper (doesn't get any kudos on this forum!)

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