Kitfox Aircraft Stick and Rudder Stein Air Grove Aircraft TCW Technologies Dynon Avionics AeroLED MGL Avionics Leading Edge Airfoils Desser EarthX Batteries Garmin G3X Touch
Page 81 of 81 FirstFirst ... 31717778798081
Results 801 to 807 of 807

Thread: Dual STI build log

  1. #801
    Senior Member
    Join Date
    Nov 2019
    Location
    Leavenworth WA
    Posts
    353

    Default Re: Dual STI build log

    Quote Originally Posted by Eric Page View Post
    ........A better design would rigidly mount the stab to a small linear bearing running on a precision-ground chromed rod. It would weight a little bit more, but it would constrain the stab against hammering in turbulent airflow. It's probably not a difficult retrofit for someone with some fabrication and welding skills (not me, in other words!).

    Dang it Eric!! I was digging my credit card out to put in my order from you!!!
    Gary (Geek) Phenning
    Leavenworth (Not the Prison), WA
    Kitfox STi in Building Stage

  2. #802
    Senior Member
    Join Date
    Jun 2008
    Location
    wales,ny
    Posts
    666

    Default Re: Dual STI build log

    Also check your rod end bearings on the aft ends of the horizontal stab brace. I have found they wear and start getting sloppy so i've replaced them several times in the last 19 years . Bruce N199CL

  3. #803
    Senior Member jrevens's Avatar
    Join Date
    Aug 2009
    Location
    Arvada, CO
    Posts
    2,050

    Default Re: Dual STI build log

    Good advice Bruce. Don't forget to give those a couple of drops of Tri-Flow during annual condition inspections at least.

    Is that "hammering" an issue with just the STI, or have others experienced it too? I never have in my 7SS. I would be very cautious about flying at an attitude, speed & flap setting that creates that kind of disrupted flow over the tail. Not only is it probably pretty hard on the structure, but it wouldn't be fun to suffer a stalled horizontal tail that's creating a lot of downward force to maintain that attitude, and suddenly you're hanging from the seat belts and looking at the ground, especially at lower altitudes. I don't know what the possibility of it happening in a Kitfox is, but I unexpectedly experienced it in another design during a test flight. It's called a "bunt" and it wasn't very fun when it's unexpected, and especially when low to the ground. If you've been there you know what I mean.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE

  4. #804
    Senior Member
    Join Date
    Dec 2017
    Location
    Mapleton,UT
    Posts
    1,091

    Default Re: Dual STI build log

    My experience is pretty limited in regards to the 7SS, but I know both our STI's do it. I also know Trent's does it as well along with the factory STI. I don't think it has to do with the wing though, but the engine. I think its the spiraling of the prop wash wrapping around fuselage on high power settings on turbo engines. I think the spiraling prop wash reaches farther and shakes the tail. Really cant avoid it on takeoff unless you want to takeoff low power, but that would be silly! On my maiden I about aborted it thinking I had a imbalanced prop or something else. We messaged Brandon and Trent and they said I think you are just feeling the prop wash. Its really not a issue, just others running 915 or Edge engines be aware that you will get feedback in your control stick on high AOA's like takeoffs or steep climbs. Once you start getting play in the tail slider, seems to wear out the delrin making "stick shaking" worse. So far the TPU is working awesome. The only play I have now in the tail is the slight play in the trim motor.
    Dustin Dickerson

    Building 7ss STI x 2
    Oratex
    29" shock monster
    EP912STI 155hp
    Garmin
    N33TF......FLYING!
    N53TF......FLYING!

  5. #805
    Senior Member Kitfox Pilot's Avatar
    Join Date
    Aug 2019
    Location
    Spring Garden Illinois
    Posts
    690

    Default Re: Dual STI build log

    Quote Originally Posted by jrevens View Post
    Good advice Bruce. Don't forget to give those a couple of drops of Tri-Flow during annual condition inspections at least.

    Is that "hammering" an issue with just the STI, or have others experienced it too? I never have in my 7SS. I would be very cautious about flying at an attitude, speed & flap setting that creates that kind of disrupted flow over the tail. Not only is it probably pretty hard on the structure, but it wouldn't be fun to suffer a stalled horizontal tail that's creating a lot of downward force to maintain that attitude, and suddenly you're hanging from the seat belts and looking at the ground, especially at lower altitudes. I don't know what the possibility of it happening in a Kitfox is, but I unexpectedly experienced it in another design during a test flight. It's called a "bunt" and it wasn't very fun when it's unexpected, and especially when low to the ground. If you've been there you know what I mean.

    John I don't notice any hammering just my stick vibrates in my hand where it is normally very smooth otherwise. This is at an extreme AOA and full 5800rpm in my case. I can drop to 5500 rpm and it goes away. That's why I was blaming it on prop vibration but maybe it is the prop blast. I am still not sure. In my case It's not an attitude you accidently get into, it's beyond a 45% steep full power climb out.
    It doesn't happen on a normal 1500 fpm takeoff climb out. Harlan
    Harlan and Susan Payne
    Sold Piper Archer
    Flying FarmFox STI Kitfox N61HP
    Rotax 915is, Airmaster prop
    https://www.youtube.com/channel/UC5A...oCVUP15G0uB-Yw

  6. #806
    Senior Member
    Join Date
    Jun 2008
    Location
    wales,ny
    Posts
    666

    Default Re: Dual STI build log

    Quote Originally Posted by jrevens View Post
    Good advice Bruce. Don't forget to give those a couple of drops of Tri-Flow during annual condition inspections at least.

    Is that "hammering" an issue with just the STI, or have others experienced it too? I never have in my 7SS. I would be very cautious about flying at an attitude, speed & flap setting that creates that kind of disrupted flow over the tail. Not only is it probably pretty hard on the structure, but it wouldn't be fun to suffer a stalled horizontal tail that's creating a lot of downward force to maintain that attitude, and suddenly you're hanging from the seat belts and looking at the ground, especially at lower altitudes. I don't know what the possibility of it happening in a Kitfox is, but I unexpectedly experienced it in another design during a test flight. It's called a "bunt" and it wasn't very fun when it's unexpected, and especially when low to the ground. If you've been there you know what I mean.
    Hi John , Like you , I have not experienced this issue on my IO-240 powered Series 5, and was interested to see whats causing this on the new STI's. The wear on Dustin's delrin was an eye opener. Hope they can find the source of this anamoly. Bruce N199CL

  7. #807
    Senior Member jiott's Avatar
    Join Date
    Jun 2010
    Location
    Portland, OR
    Posts
    2,787

    Default Re: Dual STI build log

    I don't experience this vibration on my 7SS with 912uls, but over about 10 years, 1200 hours, my Delrin slider blocks developed some minor wear which caused some side-t0-side slop in the horizontal. Instead of replacing the blocks, I applied a single layer of some heavy duty 3M Teflon anti-chafe tape to each side of the square tube where the blocks ride. It totally eliminated the slop and has not come loose for several years now. I am thinking the Delrin to Teflon wear surface will last nearly forever. Anyway, FYI a simple easy solution if you catch it before the slop gets too bad.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

Posting Permissions

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