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
Results 1 to 9 of 9

Thread: Can I fit SS7 wings to a Kitfox 5?

  1. #1
    Rooster's Avatar
    Join Date
    Dec 2011
    Location
    Stutterheim, South Africa
    Posts
    145

    Default Can I fit SS7 wings to a Kitfox 5?

    Sorry if this has been asked before!
    I recently bought a KF 5, and I was wondering if there is a difference in the wings of a SS7 and the 5? Can I fit a set to the 5 fuselage? Is it even worth trying it?
    Can it even be done?
    What, in layman's terms (that I can understand by looking at my 5) is the difference between the SS and my 5 (2003 model).
    Which differences will concern me at my home at 4000 ft in warm South Africa? Driven by a Franklin 4 cylinder 125hp @ 2800 Rpm.
    I understand there are cosmetic differences - What are they?
    Bear in mind that I am most interested in taking off short and landing short.
    Cruise takes second place in my mission:- FUN!

  2. #2
    Senior Member
    Join Date
    Dec 2008
    Location
    Garland, Texas
    Posts
    1,476

    Default Re: Can I fit SS7 wings to a Kitfox 5?

    The SS7 has the ability to convert for a Tail Wheel to a Nose Wheel built into the Fuselage. Also the Tail Rudder shape is a little larger and is squared off at the top. I do not believe there is any difference relative to the Wing, or Ailerons.
    Paul Zimmermann
    LSRM-A
    Garland, Texas

  3. #3
    Senior Member t j's Avatar
    Join Date
    Oct 2009
    Location
    Ellensburg, WA
    Posts
    861

    Default Re: Can I fit SS7 wings to a Kitfox 5?

    The model 4 through 7 wings are all the same size, shape, airfoil. There are some different strut lengths so different strut attach bracket locations. have someone measure the distance from root end of the spars to bolt hole for the strut rod end on a seven to compare to a model 5.
    Tom Jones
    Classic 4 builder

  4. #4
    Senior Member Dave S's Avatar
    Join Date
    Oct 2008
    Location
    St Paul, MN
    Posts
    1,833

    Default Re: Can I fit SS7 wings to a Kitfox 5?

    Rooster,

    It is my understanding that the wings on the 5 through 7 & SS are identical, including the flaperons with the exception that the standard wing tips on the current SS uses a short wing tip rather than the hoerner style (like you have). So, to get S7 wings on your bird, all you have to do is use the ones you already have!.... how's that for frugal.

    Regarding what a person can do to get their best short field performance, probably the best first action is to become totally familiar with the characteristics of your bird and practice short field technique with what you have - and practice with all flap settings - the best flap setting might be different for takeoff than for landing short. I diddled around for a couple years before I felt I had developed the skill to do an actual 900 foot runway......and it worked out fine with room to spare. The reason I mention pilot technique is; although I know Kitfox pilots are on the upper end of the short field performance curve....in practice I see an awful lot of planes of all types burning up 3/4 of our 2,800' runway just because the runway is there.

    One thing you have going for you is the horsepower of your existing engine. Also, one of the most effective short field performance ingredients equipment wise is a low pitch climb prop......as long as you aren't so concerned with cruise speed. With the available HP, you should be able to suck the grass out by the roots on a short takeoff run if you have a prop optimised for takeoff/climb. A low pitch prop also helps with shortening the landing roll if you throttle back to less than no-thrust RPM on short final....the prop disk pretty much acts like a big flat piece of plywood and adds a lot of drag. There are a number of threads on this list regarding KF flyers who spend time minimizing idle RPM to assist with short field performance - a good thing to search on.

    One thing KFs seem to like is being flown as light as possible. While there is not a lot a person can do about the basic weight of the airplane, making sure the plane is not loaded with non essential baggage helps as well as not carrying the full 26 gallons of fuel in the wingtanks if you can do that with the mission. I suppose, tongue in cheek, a person could consider going on a diet; but, that is sort of like breeding elephants....takes two years to get results

    FWIW - I run a Warp Drive prop with a cruise setting in front of a 100 HP Rotax......And I have been careful not to have the idle RPM set higher than it needs to be. That gets me in and out of any airport I have encountered, even those slightly less than 1,000 feet with room to spare....However, I would never have attempted that with just a few hours of KF experience.....lots of practice gets you very close to the advertised short field performance but we do need the practice first. Another minor point which I have found that helps.....not running low pressure in the tires....a higher pressure reduces tthe takeoff roll a minor amount due to reduced rolling resistance. Tire pressure is one of those things we have widly varied opinions about depending on the tires and the landing places we pick. I keep my tires at 25 PSI and then try not to score too high on the richter scale with my landings.

    Sincerely,

    Dave S
    KF7 Trigear
    912ULS Warp Drive
    St Paul, MN

  5. #5
    Senior Member kmach's Avatar
    Join Date
    Nov 2009
    Location
    Cupar, SK, Canada CLC4 Loon Creek Airfield
    Posts
    641

    Default Re: Can I fit SS7 wings to a Kitfox 5?

    Hi,
    As far as I know, the fuselage and wings on a 1550 lb gross model 5 are the same as the 6 and 7.
    The 6 and 7 have improvements /aditions to the 5 design.
    The 7SS is a lighter where possible 7.

    The model 7's have a larger elevator than the model 5.
    This helps with pitch authority at slow speeds and I think would be a plus for short field ops.

    Vortex Generators might help somewhat.

    An inflight variable pitch prop helps allot .

    What is your empty weight with the Franklin ?

    What is your STOL goal in terms of length and obstacles?
    Kevin,

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

  6. #6
    Rooster's Avatar
    Join Date
    Dec 2011
    Location
    Stutterheim, South Africa
    Posts
    145

    Default Re: Can I fit SS7 wings to a Kitfox 5?

    Hello All.
    Thanks so much for the replies!
    Dave S - You have taught me a lot, thanks. I was realising these things and you confirmed it and drew my attention to pertinent issues. With two up, I am still getting it wrong on the flair, as I used to hang the C170 there on the prop with a touch of power and grease a 3-pointer for a 300 foot landing with two up, but I have found that the "touch of power" on a Kitfox gets me ahead of the drag curve again and I end up plonking it down untidily. I am battling to get her close enough to the ground and to the stall to for the neat 3-pointer. Like you say- PRACTICE!
    I am still too afraid to use 2 notches of flap with two up and no baggage, as all those I have spoken to so far have told me that I am likely to not be able to get the tail down and may stick the prop in. I am managing to peg the blue line on approach, as I have slowed the idle down to 750 RPM. I have a Warp Drive at 13 degrees. (she arrived with it). I have been reading the builder's books and he did try 12 degrees and got 2550 RPM static, but he wasn't prepared to cruise slowly. I might try that for a blistering take-off, but I have already got 800fpm climb from my 4000ft asl field on a 25 deg Celsius day. KMach- Thanks. I have a 881 pound empty weight 5. I am going to try and get her on a diet by taking out one of the two fuel pumps, look at doing a new exhaust and changing the carb heat shroud to a little one like the Robinson helicopters have. Then I can move the battery forward and put a smaller one in etc. There are a couple of other things that I can work on as time and money become available.
    My goals are to handle a 350-400 foot ground roll for landing and take-off and I will try to land in our local Lucerne (alfalfa) pastures for tea and a chewing of the fat with my brothers and other friends.
    The bottom line is; Thanks so much guys! I really value the input and I am having fun trying it all out.
    I will be practicing a lot. SAFELY!
    Regards
    Reid

  7. #7
    Super Moderator Av8r3400's Avatar
    Join Date
    Jan 2009
    Location
    Merrill, WI
    Posts
    3,044

    Default Re: Can I fit SS7 wings to a Kitfox 5?

    Where does your center of gravity (cg) fall?

    There should be enough elevator authority to handle full flaps on landing without nosing over. You may need to move some weight around to get that more to the rear.
    Av8r3400
    Kitfox Model IV
    The Mangy Fox
    912UL 105hp Zipper
    YouTube Videos

  8. #8
    Rooster's Avatar
    Join Date
    Dec 2011
    Location
    Stutterheim, South Africa
    Posts
    145

    Default Re: Can I fit SS7 wings to a Kitfox 5?

    Here is the w&B.

    I want to go up and practice at a constant altitude and really feel her before I bring it back towards the ground.
    When we went to fetch her and fly her the 500 miles home, we felt as though the tail was going to drop out at short finals, but I suspect that we were just too unfamiliar with the type. (both myself and my test pilot pal had not flown one before.).

    This was at loaded baggage and two adults with a good load of fuel (70litres).
    Attached Files Attached Files

  9. #9
    Senior Member jiott's Avatar
    Join Date
    Jun 2010
    Location
    Portland, OR
    Posts
    2,959

    Default Re: Can I fit SS7 wings to a Kitfox 5?

    On my SS7 I readjusted the horizontal trim ballscrew to give more nose-up range (less nose-down). The readjustment used essentially to the bottom of the slot in the tail covers. This gave me enough nose up trim for full flap landings, but still requires some back stick elevator pressure. There is plenty of elevator authority for this. I can't say if its the same on a model 5, but suspect it is.
    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
  •