LSaupe

Thanks for the images TJ.  I see you have your baffles (I called them wings on the first post) on an angle to better mate with the top of the ribs.  I did the same.  My drawing seemed to indicate keeping them flush with the top surface of the turtle deck, which would cause a large gap near the rear of the rib (between the baffle and the rib).

Are these strong enough to not flap around and damage the paint and/or rib?  I am assuming so as I see no reference to secure these in any manner (though I have seen a local Avid tape these down to the rib).

Anyone have a good pic of the turtle deck for a Model III (or similar)?

Trying to figure out the wing placement.  From what I gather it is to block bypass wind between the wing and turtle deck.

However, the wing will lay just over the rib foward, but have a huge gap aft (if keeping the same attachment line as suggested with the turtle deck.  Do they get bent down close to the proximity of the rib perhaps and just flap there?  Just seems like a low strength odd piece of aluminum hanging out there.

Do these even work and are they worth the trip?

Larry

TJay,

      It would be somewhere between having full flaperons, and the Avid guys who extended the wings and used the shorter flaperons, or with an extension on the control end - it still works...maybe not quite as well...

      There is at least one on here that extended his short wings.

EdMo

       Larry should be able to fold his wings by unhooking the control rods.

Interesting thought.  I disconnect the control rods regardless.  Doesnt help with the folding issue. I also remove my aft flaperon hing bolts and rotate the hinge updward which then gives clearance to fold.  Kind of a pain in the shorts and time consuming, but does work (kinda).

Great stuff guys, and yes I was using the book arms, which do not include the leading edge extension. I need to correct those and re-crunch numbers.

Thanks again for all the feedback and the research some have done here. Very much apprecaited. This 90% done and 90% to go phase is taking much longer than anticipated.

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).

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?

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.

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"

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.  

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.

Performed weight and balance today. Adding the larger rudder/vertical stab, elongated elevator and rear header tank has taken me out of W&B for the most aft CG condition. I need 300 in-lbs (fwd) to get me back in. Hate to add ANY weight, but not much I can do now (nothing to move). Battery and ELT are forward under the dash (behind the firewall). Are there any good places to add in weight forward? Probably distributed would be better than concentrated.

No GPS interface for this unit.  Just need to get something in the bird to pass the DAR inspection.

My new ELT came with an external antenna (looks like be a standard type VHF about 19" long).

Question is:

1) Can this be mounted internally or does it actually need to be external?

2) Any chance this could be "T" 'd in with the VHF antenna (vice drilling and installing another)?

All:

Chris has a Sigtronics SPO-42 unit.  Any thoughts on if this would be compatible or any other feedback?  I have an ICOM PTT switch, which plugs directly into the hand held radio harness (Icom A-14).  Would that still work fine (connected directly to the radio harness) or would I need to adapt through the intercom or split to inyercom and radio harness?

The ICOM PTT and Sigtronics PTT connectors are of different diameter (hopefully there is a converter somewhere).

Larry

Purchase a set of door frames today!

Looking for a nice used set of model IV door frames to update my Model III.  Modified for a wide body kit would be a further bonus.

Larry S.

Nice nice nice!  Looking sharp!  It sure has come a long way,

Doug, Sent you a PM

Great feedback and suggestions! Thanks.  Chris, sent you a PM.

Looking for recommendations on an intercom system.  Two people.  Prefer battery powered. 

Inetgrating with GA headsets and an Icom hand held radio.

Looking for an original Kitfox tow bar (to fit a model III).  Would also be interested in drawings.

Larry S.

Actually my installs started to leak so I contacted LEAF.  The original cloth covered hose (gray head) has been discontinued and is replaced with a new hose (not cloth braided)) which is almost 2x I.D.  Went on great this time.

Quick update.  Ended up going with the upside down rods and those would just touch at full deflection.  Added a bit of curvature to the rod (each side) and the world is a happy place.  Will forgo the folding problem for now.

Thanks to everyone for providing feedback on this problem.  Thanks to Tim T for making the trip up today to help in the final resolution and rigging!

Larry

Larry,

    I see now that the elbow is inside of the turtledeck, as it should be.

Just a real wild idea - I know the book says it should go as you have it - BUT, what if you could turn the control rod upside-down, so the small end would be sticking up? - Crazy ideas sometimes work! 

    I think the max degrees for the flaperons has been posted before - some say you can get reversal of controls beyond a certain degrees - others have exceded that and did not have the problem.

    I would bet that Doug has the numbers, and Suberavid has exceded them!

EdMO

    I cut 2.5 inches off of my rib tails, but mine is not regular Kitfox....

Ed might be on to something here.  I turned the gray control rod upside down (the bulky weldment is now down near the mixer).  This helps a great deal.  Any reason why not to run it this way?  Seems like a simple way to go on the surface.

Jim,

     Agree:   Unless it is in the FARs, It ain't legal - Someone would have to prove it to me.

And, Phase 1 and 50 miles is SOLO - If you put another person in the plane even in the pattern, you must have an ELT, at least that is the way I understand it.

EdMO

Thanks Ed.

However, for clarification, Phase 1 testing is authorized 2 pilots in the cockpit (through the additional pilot program AC90-116).

I does seem some of this is DAR specific as well.  Local EAA member you recently went through inspection needed it to pass (or at least make that person happy).