Results 1 to 7 of 7

Thread: Ground Adjustable Prop for acro

  1. #1

    Join Date
    Nov 2011
    Posts
    11

    Ground Adjustable Prop for acro

    Currently looking to purchase a new prop for my aerobatic aircraft. I'm planning on purchasing a 3 bladed Catto but was curious if anyone has used a ground adjustable prop on their aerobatic aircraft?

  2. #2

    Join Date
    Oct 2011
    Location
    New Hampshire
    Posts
    1,300
    My observation has been that modern ground adjustable props are generally used on airplanes that fly with 80-125hp.

    In 11 years of aerobatic competition, I have never seen an aircraft with a ground adjustable propeller. The fixed pitch props get run up to as much as 3200rpm, so an adjustable hub needs to be pretty rugged. And the fixed pitch prop manufacturers seem to be pretty good about repitching if you need it. So there really is no need to field adjust the propeller pitch.

    Best of luck,

    Wes

  3. #3

    Join Date
    Nov 2011
    Posts
    11
    Thanks for the reply Wes those were my thoughts as well

  4. #4

    Join Date
    May 2012
    Location
    Creswell, OR
    Posts
    6
    What about the new breed of GA props from Whirlwind and Sensenich that are designed for RVs with 360s on them? Obviously these are aimed a little more towards speed than anything else, but surely they would be able to handle at least sportsman to intermediate acro since they're designed for RVs.

    I've been thinking of putting one of these on my Pitts when it's finished to get good acro performance but also good cruise performance when I want it (eg. going to and from contests). Does anyone have any experience with these? Any opinions?

    http://www.whirlwindpropellers.com/g..._lycoming.html
    http://121five.com/stories_new.aspx?story_id=1133

  5. #5

    Join Date
    Jul 2011
    Location
    Clarklake, MI
    Posts
    2,448
    Quote Originally Posted by svanhatt View Post
    I've been thinking of putting one of these on my Pitts when it's finished to get good acro performance but also good cruise performance when I want it (eg. going to and from contests). Does anyone have any experience with these? Any opinions?
    No experience but I would call Jim Rust at Whirlwind and he will tell you straight up if it's a good idea or not.

  6. #6

    Join Date
    Oct 2011
    Location
    New Hampshire
    Posts
    1,300
    Almost all "ground adjustable" props only get adjusted a few times and then never touched again. It appears to me that most owners put them on, look for a good setting, and then leave them at that setting. Now if you are talking about adjusting them to go to a contest, at the contest, and again when home, I think that you are giving yourself one more item to worry about, have to triple check, and potentially get wrong, resulting in low contest scores. You have to carry more tools to work on the prop and most acro ships have limited space in the first place.

    And the next question is whether the hub is up to the stress of acro. We have suffered through the expensive Hartzell prop hub AD's over the years, which suggests that the rapid maneuvering of acro is going to find the weak spot in any new hub design. Can you afford to be a test subject? While the prop in question may be great, the lack of acro fleet experience suggests that you should be prepared financially in case this experiment does not work out. Of course, if you go through the season and collect trophies everywhere you go, you look like a genius. But in the end, your choice of propeller will have little to do with that result.

    Best of luck,

    Wes
    N78PS

  7. #7

    Join Date
    Oct 2011
    Location
    New Hampshire
    Posts
    1,300
    So if the original poster is still reading this, today, at the Sun-N-Fun, I went to the Whirl Wind booth and looked at their ground adjustable prop. It turns out that they use the same hub and blades as their constant speed prop with some different internal parts. But their ground adjustable prop apparently can be converted to constant speed with a swap of internal parts.

    So it looks like the unit can do acro, but to "shift gears" you have to remove the spinner to access the front of the hub, make you adjustment with a big screw driver on a shaft at the front middle of the hub, lock that down and then reinstall the spinner.

    So while I personally do not recommend adding propeller adjustments to the contest arrival and departure todo lists, it appears that it could be done.

    Best of luck,

    Wes
    N78PS

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •