Activity Stream

Activity Stream



  1. Av8r3400 added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Both of my model IV airframes use (as do all kitfoxes) the leading edge of the wing as the datum point.
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  2. TJay added a post in a topic Parachute installation   

    canister, VLS, or soft pack?
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  3. Altifly added a topic in Avidfoxflyers General Hangar   

    Parachute installation
    Hello,
     
    thank you for opening me acces to the forum ... I'm french avid owner, and at the moment my plane is having a fuselage revision, new covering soon
    I have a BRS 900 and wish to install it, but I can't find any installation picture exemple .. I want to be carefull about weight balance too, is there any possibility to install in front?
    thank you in advance for help
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  4. EDMO added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Jim
         I agree - as a practical measurement should be from front of wing -
        However his cg limits, as listed in the manual, are written as measured from the front of the spar, as are all dimensions for fuel, pilot, wheels, etc - if his manual is like some others I have read.
         I don't know if Larry measured or changed all the dimensions, or went by what was listed in the manual.
    The KF3 manual does not include any additions to leading edge or tail, as none were available at the time the manual was written.
         If you change the datum line location, you have to change all the other dimensions, and that is not "by-the-book".
    EdMO
         My plane is a Foxy Flapper, a different size wing, with no kit or manual, and I have to figure and write my own limits -
    but that is a whole different story.
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  5. LSaupe added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Ed, Yep, I would make it if I corrected back to the spar.  Ultimately it may bear down to if the cuff changed the center of pressure on the wing at all.  Pressure being more set by the local wing geometry vice the leading edge (just a guess).
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  6. 1avidflyer added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Ed, I think you are correct, my memory says it's the same for all Avids (A,B, C, MK IV). As far as measurments, I would think front of wing is front of wing. A leading edge extention would move the front of the wing forward, and so that is where I would measure from. Jim Chuk
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  7. EDMO added a post in a topic KF FLAPERON   

    Rick,
         Where are you located?   I have a left KF1 flaperon but don't want to crate and ship it - I am near St.Louis, Missouri.
    EdMO
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  8. EDMO added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Jim,
          I am probably the least knowledgeable about Avids, but I am almost certain that Leni said all Avid wings are the same cg range - maybe not counting the Airdale and Magnum - but I think my Magnum book lists about the same cg range as the other Avids - I checked on that, and the Magnum cg is 11.185 to 17.5 - guess because it's longer.
    The main thing that changes is the gross weights.
    LarryS,
          The Kitfox 3 W/B uses the front spar as the leading edge for all measurements - Would you be OK in aft cg using that measurement?   The plastic leading edge addition is a Kitfox 4 or 5 modification you made, and not by the manual, so you might get by with front spar measurements and be "by the book"? 
    EdMO
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  9. 1avidflyer added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    I tried to edit my last post after I sent it. Second sentence should say "It's profile is nearly identical to the Kitfox 3 wing". Having trouble editing for some reason.... The heavy hauler wing uses thicker walled spars, more ribs, and shorter length, but the shape is very similar. Jim Chuk
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  10. rickpabon added a topic in For Sale and wanted, you got it, I want it   

    KF FLAPERON
    Hi guys,
    Needing to get a pilot side Flaperon for a KF2. John an Debra will be looking into manufacturing
    these again sometime in the winter. Brett at Airdale is not able to provide service at the
    moment. I understand some Avid Flaperons may also fit. A used one will suit me fine but if there
    is anyone that can build a new one, drop me a
    line.
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  11. 1avidflyer added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Avid W/B envelope is forward: 11.185", Aft. 16.5" That is with the MK IV Heavy Hauler wing. It is nearly identical to the Kitfox 3 wing. If you are really worried about the guy doing the check flight not wanting to do it, add just enough weight as far forward as you can to get it into the Kitfox limits for his flights, and you can remove it later if you like. Jim Chuk
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  12. LSaupe added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    I hear ya.  I am not trying to beat a dead horse, but unfortunately the letters don't appear to apply to the Model III.  Add to the fact that I will not be doing the functional check flight (EAA Flight Advisor will be doing that for me).  Just looking for something a bit more concrete here that indicates this increase in aft CG is acceptable/reasonable to increase the comfort factor (or at least allow for an educated decision).  The only documentation I have, that covers the Model III, is the Model III build manual with regard to CG limits.
     
    The arguments sound very convincing, but unfortunately no paper trail appaers available until I do my own testing.  I have contacted Kitfox themselves to see if they can clarify the letter 30A applicability, so maybe that will be what I need here.
     
    By chance Is there anything on the Avid lmits with the under camber wing?
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  13. EDMO added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Tie a helium balloon to the tail and re-measure - I think you are too concerned about a fraction of an inch on an outdated W/B because of the smaller elevators on the early planes - Your plane will gain weight as time goes by anyway.   Keep the letter and references from Kitfox on file, and use that to verify larger cg range.  The inspector will not weigh your plane - and probably will not read your W/B sheets - just verify that you have them.
         Sounds like you need a heavier prop like a 3-blade Warp Drive that most use, then you could haul a bag in back.
    EdMO
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  14. LSaupe added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Interesting that the original Model IV aft CG is 1/2" further back than the Model I, II,III.
     
    Also that the leading edge forner is also 1/2".
     
    Maybe the Model IV this was standard (having the former) and they added that 1/2" in to the datum?
     
    "If" I can take credit for that 1/2" I am fine.
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  15. LSaupe added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Might be splitting hairs here, but one sensitive spot in the measurement is the tail wheel measurement.  Long arm with low weight.  Gonna check this with another scale. a 2 lb error would get me there, however, this could go either way right?  I have never seen anyone indicate an incertainty value with the measurement, so it might be warranted.  Though the seat of your pants is most likely the best measument.
     
    Also, the leading edge location.  Looks like the leading edge added former is an optional install.  Mine has these installed, which causes the reference point (leading edge) to be further forward than if it did not have these. So... what are the Kitfox limit numbers based on (with or without the forms on the leading edge)?  I have seen a few without them, but assume they used the same procedure to check CG?
     
    My numbers are as follows:
     
    Empty CG: 13.84"
    Most forward: 14.29"
    Most Aft:14.71"
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  16. EDMO added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Good Post Larry3400,
         He may learn something from reading the posts in Akflyer link.   I went back and read it too.
    Marshawk,
         What numbers did you finally come up with?
    EdMO
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  17. Av8r3400 added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Here's the lik to Leni's post on CG issues:  Link
     
    Summary:  The wing flies awesome at 16-18".  20" is workable but you may need the help of flaps to get the nose down in case of a stall.
     
    My friend Dave built his hybrid with an extended Avid C fuselage with late model Kitfox wings.  His empty CG is at 16-1/8".  The extended tail gives authority to control pitch with the aft cg, without issue.  My Mangy Fox, with the enlarged tail surfaces will be more aft than my stock yellow Kitfox.  I have no worries about loading my extended baggage area to an 18" CG.
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  18. EDMO added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Not too sure about the earlier models with smaller tails, which you have changed, but this confirms what I was saying about designers using 30 to 33% chord - 32% would be 16.12 inches aft cg, and still think this may be conservative.  Talk to Leni.
    I think my personal cure for weight and balance would be to go on a diet !
    EdMO
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  19. LSaupe added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Found this in the Kitfox service bulletins.  However, it applies to the Model IV's (shown), however the website seems to indicate that it applies to M1 through M4 (see right side column).  
     
    http://www.kitfoxaircraft.com/Service%20Letters.htm
     
     Anyone seen a pressure distribution comparison between the two wings?  Curious were the center of pressure point is between this two wings over the flight range.
     
    *************************************
     
     
    SERVICE LETTER #30A
    DATE:                    May 1, 1994   revision  September 7, 1994
    SUBJECT:                              Aft CG Limit
    APPLICABILITY:                All Model IV-1050 and Model IV-1200 Kitfox's
    FROM:                   SkyStar Engineering
    This service letter is intended to provide you with information regarding the operating center of gravity range for your aircraft.
    We have completed a series of flight tests on our factory Model IV-1200 Kitfoxâ„¢, and our findings support the expanding of the allowable CG range.
    The new aft CG limit for Model IV-1050 and Model IV-1200 Kitfox's and Model IV-1200 Speedsters is 16" aft of the leading edge of the wing.  The old limit was established at 14.78", but that has been found to be too conservative.  At 16", you will find that loading your Kitfoxâ„¢ within the CG range to be much easier.
    Please make the appropriate changes in your builders manual and/or flight manual referring to this Service Letter.
    We are also aware that many of the Model IV-1200 Builder's Manuals were shipped with weight and balance data sheets that incorrectly stated the aircraft gross weight as 1050 pounds, and that some builder's had problems getting their aircraft registered at the correct gross weight of 1200 pounds.  We have re-written the section and can send a corrected version on request.  
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  20. EDMO added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    I think a 3-blade Warp Drive or an IVO IFA up front would allow him to put some baggage in the back.
    TJay,
    We don't have 53 degrees wake-up here yet, maybe 60 - but the temps are a lot better than the 90's with 100% humidity we had.  Could be worse - I have seen it 112 to 115 here in July and August!
    LarryS,
          I think Leni's Avid C/MkIV plane may be about the same as your KF3/elevator mod - except his heavy prop.
    I suggest you try a PM to Akflyer and talk to him about W/B.
         
    EdMO
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  21. Av8r_Sed added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    No 20 lb chunk of lead on mine, but I do have an Ivo med 2 blade and Rk400 clutch up front.
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  22. TJay added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Every Kitfox 3 I have ever seen with a 582 on it has a 20lbs chunk of led hanging under the front two bolts of the engine mount.
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  23. TJay added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Isn't that great ED when you step outside in the morning to 53 degree weather, really makes for a better day.
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  24. EDMO added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Larry,
          I think you are needlessly worrying about a fraction of an inch. 
          I believe as the "manufacturer" of your plane you can set your own cg limits. 
         Phase 1 has you list the limits you flew it at. 
    Most designers use 30% Chord which would be 15.3", and some even use 33% which would give you almost 17".  
         I think you need to have a conversation with Leni (Akflyer) about this.  
    I believe with elevator changes your aft cg can be increased, and Avid already is increased.
          I am going to check both my Kitfox and Avid manuals to see what % they used, and get some figures in inches for each.
    I will get back to you - working on my wings today since the weather finally turned cooler and humidity went down.
    EdMO
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  25. LSaupe added a post in a topic Model III Weight and Balance - Need 300 in-lbs fwd   

    Hi Ed:
     
    Using leading edge as a datum, most aft CG is 14.71 inches.  Max allowable from the build manual is 14.28" (28% MAC).
     
    Yes, figuring pilot, copilot and fuel.  14.61 inches (no fuel) vice 14.71 (full fuel - 13 gal)
     
    Heavier tires won't gain much at all because the arm is so dang small (3.25").
     
    However, I am using the book values for arms of pilot/copilot and wing tanks.
     
    P/CP = 15.8"
    Wing Tanks = 15.97"
     
    This may sound odd, but would a small weight disc at the prop hub make sense?  Gets it out front and keeps the MOE reasonably low, though do hate to make additional weight dynamic.
     
    Yes, max GW is 1050.
     
    Maybe Doug can chime in here as well on where his Model III sorted out during W&B.
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