Unstarted KF Model1 SN#111- Questions

[SkyHook]

Greetings TeamKitfox
This is my first post. I've followed this forum for a couple years now. I purchased an unstarted Kitfox Model 1 kit last Year. Serial#111. all of the metal tubing was covered in a light film of rust. It had been stored in the owner's workshop for the past 28 years. I inventoried the kit and found that everything is accounted for except the plastic for the windshield and doors.
So far I have used scotch bright on all of the tubing to remove the rust, then sprayed it with epoxy primer. During the winter I have done a lot of research and have questions on how to proceed on a few things.

1. From what I've read, it seems to be recommended to add reinforcements to the vertical rudder pedal tubes where they are connected to the bottom horizontal tubes. I removed the epoxy primer from those areas to weld triangular gussets in place. I cut the gussets from .040 4130 sheet.

2. It seems t be a good idea to extend the vertical fin and rudder. I plan to use 035 4130 tubing welded to the top of the original rudder and over hang above the vertical fin. Any pointers on how that should or should not be done?

3. After some research, I decided that it was important to me to have some aileron differential so I cut out the mixer mount tubes that were in the fuselage aft the seat area. I have designed and am building a mechanism like what is standard on classic model 4 and newer, The Kitfox catalog has a retrofit kit but is not available for the Model1.

4. Is it recommended to add reinforcement gussets around the elevator welds near the control horn?

5. Is anything salvageable in the covering and finishing kit? I have 28 year old unopened cans of polytak, polyfiber, and structural epoxy. I guess that is all expired and should not be used. What about the bias tape and trhead? I have the roll of Dacron cloth too. Is it too old to be used?

6. The 20" balloon tires still have air in them and seem to be soft, are they garbage after sitting so long?

7. The Rotax 532 is still in the box. I assume it will need to have a mechanic go through and replace or upgrade some parts.

Any advice or direction would be appreciated. It's almost warm enough to resume building again but I don't want to get going just to do it over again.
Thanks, Jim B.
- btw - I chose the skyhook user name because I have a hook for a left hand. Another story for another day...

[wheelerg]

Looks like you have a great project ahead of you, good luck with the build as I wish I had the patience to build one.
Gary

[DesertFox4]

Skyhook, sounds like all the covering products are way too old to use. Not sure if the fabric is still useable. I'd be talking to PolyFiber before using it.
Good idea to reinforce the rudder pedals.

Seek out SkySteve in Utah on the tail modifications. He did a great job on his and his personal page has some very good photos of the modification. You might also search for his posts on the subject as I recall he discussed it in some detail.

Also not excited about 20 year old tires and tubes.

I have no experience with two stroke Rotax engines. Sorry.

Good luck with the project.

[SkyHook]

DesertFox, I really enjoy your YouTube videos flying around the Arizona desert. Thank you for the straight answers. I was pretty sure the covering items should be replaced. Even if they might have a little life left in them they certainly are not the best choice over new materials. I agree about not being excited about the tires. Every take-off or landing would have one more thing to worry about. I will reach out to skySteve and talk. I have studied his posts and photos on his personal site.

[Paul Z]

I would recommend going to Rotax Flying & Safety club, an find a Rotax Repairman to go through the engine.

[SkySteve]

Did someone call me in on this (DF4)?.

Hey SkyHook, (by the way, what a great name!). Feel free to give me a call (eight 0 one, 7 niner one, 4 seven 7 seven). Tomorrow is good if that works for you as it looks like it's going to snow again. I see you are just down the road from me, in West Jordan. I'm in Huntsville and my plane is at the Ogden airport.

[DesertFox4]

Steve- I just wanted to steer him towards your posts and photos. You did such a nice job on yours and I personally know how well it flies with your mods. Just want the best for our new members.:)
Got to get those lonely and forgotten kits into the right hands and get them flying. Thanks for any assistance you can give.

Hope to see you soon. BTW, no snow here in Phoenix yet.:eek:

[herman pahls]

Skyhook
Your build reminds me of 22 years ago.
Walked into a friends barn 10 miles from home to get out of the rain and found my first Kitfox (model 1 #190 ) that he had been storing for a friend since 1998.
Everything was there including instruments and 532 for $2500.
One year later I flew it with help on the covering and paint from a former Kitfox employee.
I was advised then to replace all the chemicals but I did use the covering fabric.
Seems like we welded on some reinforcements to the lower end of the lift struts and carry thru spar reinforcement which raised the gross weight from 850 to 950 pounds.
The spars also need to be the correct ones for 950 which mine happened to be.
My son soloed the airplane on his 16th birthday and with mixed feelings I sold it a month ago since a model 4- 912 ULS took its place.
The Kitfox changed the way I fly and was responsible for me still flying after 40 years.
I try to make a new backcountry landing every time I fly and seldom go above 500 feet AGL unless trying to get somewhere.
Gone are the boredom flights of going to altitude and hours later returning to earth.
I wish you well on your build and hope you enjoy it as much as I did.
Steve Wilson from Ogden, Utah is an expert on modifying model 1's and has been very generous with helping me out.

My very positive experience with the 532.

I was told then to forget the 532 and get a 582 because the 532 has single ignition and the 582 has a better power band.
Apparently if the stator of a 582 fails, both ignitions fail so the 582 does not have true dual ignition.
Steve Beauty at Airscrew Performance in Arizona checked out the engine and replaced the points ignition with a snow mobile ignition (that ignition has retard for easier starting and lower idle rpm) and told me the 532 would idle at lower RPM's than the 582.
He also rebuilt the 532 at 300 hours and said it looked so good inside it did not need to be rebuilt yet.
I flew that 532 for 13 years and 450 hours with no issues.
I tried a older 80 HP Jabiru for several years.
I enjoyed the engine but it just plain did not perform for me as well as the 2 strokes with gear boxes that allow longer props for short fields or above 10,000 feet.
Four years ago I replaced the Jabiru with a 582 Blue head.

The only way I could tolerate the 582 was to install a RK-400 clutch because the 582 will not idle nearly as low and as smooth as the 532.
I also upgraded to a model 4, two stroke engine mount (which I happen to have an extra for sale) and makes for a lot less vibration to you and the airframe.
You can land shorter if the engine will tolerate idling at a lower rpm.
Your 532 most likely has an A gear box which will need the belleville washers replaced every 100 hours where as the C box on a 582 will need very little maintenance other than oil changes.

Herman Pahls
Oregon

[t j]

Here's the service bulletin about gussets on the Elevator.
http://kitfoxaircraft.com/support/service_bulletins/sb4.htm

[Jfquebec]

Hi Skyhook...like you im building now a kitfox 1993..so all my polyfiber stuff are pass date and my fabric roll are in dark plastic bag to protect from sunlight...
So what i do ...i order new product and i test my old-new fabric...i ask to polyfiber company how to do it...you cut a strip of 1 1/4" wide by 8 " long and you put some weight on...i take four wood block to hold the fabric with C-clamp and a big bucket under and i take every steel part i have in my shop...she brake at 80 lbs..if i remember right..i will try to find a chart for that ...


Jf

[Jfquebec]

the strength of intermediate grade cotton is required. This means the new fabric breaking strength must be at least 65 pounds and the minimum fabric breaking strength at which the aircraft becomes unairworthy is 46 pounds.
Lighter weight fabric may be found to have been certified on gliders or sailplanes and may be used on many uncertificated aircraft or aircraft in the Light Sport Aircraft (LSA) category. For aircraft with wing loading less than 8 pounds per square foot or less, or VNE of 135 mph or less, the fabric is considered unairworthy when the breaking strength has deteriorated to below 35 pounds (new minimum strength of 50 pounds). Figure 3-10 summarizes these parameters.
How Fabric Breaking Strength is Determined
Manufacturer’s instructions should always be consulted first for fabric strength inspection methodology. These instructions are approved data and may not require removal of a test strip to determine airworthiness of the fabric. In some cases, the manufacturer’s information does not include any fabric inspection methods. It may refer the IA to AC 43.13- 1, Chapter 2, Fabric Covering, which contains the approved FAA test strip method for breaking strength.
The test strip method for the breaking strength of aircraft covering fabrics uses standards published by the American Society for Testing and Materials (ASTM) for the testing of various materials. Breaking strength is determined by cutting a 11⁄4 inch by 4–6 inch strip of fabric from the aircraft covering. This sample should be taken from an area that is exposed to the elements—usually an upper surface. It is also wise to take the sample from an area that has a dark colored finish since this has absorbed more of the sun’s UV rays and degraded faster. All coatings are then removed and the edges raveled to leave a 1-inch width. One end of the strip is clamped into a secured clamp and the other end is clamped such that a suitable container may be suspended from it. Weight is added to the container until the fabric breaks. The breaking strength of the fabric is equal to the weight of the lower clamp, the container, and the weight added to it. If the breaking strength is still in question, a sample should be sent
to a qualified testing laboratory and breaking strength tests made in accordance with ASTM publication D5035.
Note that the fabric test strip must have all coatings removed from it for the test. Soaking and cleaning the test strip in methyl ethyl ketone (MEK) usually removes all the coatings.
Properly installed and maintained polyester fabric should give years of service before appreciable fabric strength degradation occurs. Aircraft owners often prefer not to have test strips cut out of the fabric, especially when the aircraft or the fabric covering is relatively new, because removal of a test strip damages the integrity of an airworthy component if the fabric passes. The test strip area then must be repaired, costing time and money. To avoid cutting a strip out of airworthy fabric, the IA makes a decision based on knowledge, experience, and available nondestructive techniques as to whether removal of a test strip is warranted to ensure that the aircraft can be returned to service.
An aircraft made airworthy under an STC is subject to the instructions for continued airworthiness in that STC. Most STCs refer to AC 43.13-1 for inspection methodology. Poly- FiberTM and CeconiteTM re-covering process STCs contain their own instructions and techniques for determining fabric strength and airworthiness. Therefore, an aircraft covered under those STCs may be inspected in accordance with this information. In most cases, the aircraft can be approved for return to service without cutting a strip from the fabric covering.
The procedures in the Poly-FiberTM and CeconiteTM STCs outlined in the following paragraphs are useful when inspecting any fabric covered aircraft as they add to the information gathered by the IA to determine the condition of the fabric. However, following these procedures alone on aircraft not re- covered under these STCs does not make the aircraft airworthy. The IA must add his or her own knowledge, experience, and judgment to make a final determination of the strength of the fabric and whether it is airworthy.
IF YOUR PERFORMANCE IS. . .
Fabric Performance Criteria
FABRIC STRENGTH MUST BE. . .
Loading
VNE Speed
Type
New Breaking Strength
Minimum Breaking Strength
> 9 lb/sq ft
> 160 mph
< 160 mph
≥ Grade A
> 80 lb
> 56
< 9 lb/sq ft
> 65 lb
> 46
< 8 lb/sq ft
< 135 mph
> 50 lb
≥ Intermediate ≥Lightweight
> 35

[Jfquebec]

I try to paste the chart for fabric testing..but we dont see it really good..

Loading Vne speed. Type. Breaking stenght. Minimun breaking steaght
>9lb/sq ft. >160mph. Grade A. >80lbs. >56 lbs

<9lb/sq ft. <160mph. Intermediate. >65lbs. >46lbs

<8lb/sq ft. <135mph. Lightweight. >75lbs. >35lbs

[avidflyer]

Poly Fiber system is supposed to last for 30 years parked outside if it's installed correctly. At that rate, the fabric should still be good if it's never seen sunlight. Most likely the poly tac is dried up. I've used some fairly old poly brush and couldn't tell the difference, but supposedly the shelf life is 3 years if I remember right. Jim Chuk

[SkyHook]

I'm excited! There have been so many helpful responses. I welded the reinforcement plates to the end of my lift struts. I'm waiting for warmer weather to weld the gussets on the rudder peddles and the elevator center area. From what I've learned the pros recommend the temp of 4130 to be above 60 degrees to keep it from shock heating and cooling when it is TIG welded.

I do have a few more questions to throw in.

1. I have two shiny 6 gallon aluminum wing tanks. I guess they are no longer useful?

2. Can I use the big plastic front main tank, or is it best to install a rear header tank and buy the larger 13 gallon wing tanks? I will admit, that would make more space behind the panel.

3. Should I be starting any type of registration or communication withe the FAA?

I am attending and trying to learn at my local EAA Chapter 23. Between that and all of the thoughtful advice and comments here on this forum, I'm getting excited to make some progress.

I have designed an electric elevator and rudder trim system with 24 led bar graph position displays and driven by an arduino. It should be useful for displaying position of the flaperons also. I'm adding a linear actuator to control the flaperons instead of the manual lever. I want to get as much control on the stitck as possible, since I only have my right hand. I'm still unsure where the throttle control would be placed. I'd like to control it using my left hook. A bit unconventional for sure. Thanks for joining me in my thoughts and decision process.

[SkyHook]

Thought I'd throw in a picture of the lift strut reinforcement

[avidflyer]

As long as your plane isn't covered yet, I would think about widening the fuselage while you can do it easily. Basicly you just add additional tubing around the perimeter of the doors, and twist the doors to fit the new opening. I made my Avid MK IV 3 1/2" wider by doing this. It's not interfering with the original structure, just adding to it. Another area to consider strengthen is the seat truss. Many of them have ended up bending with landings that didn't seem that hard. I used .040" thick steel in the Avid in the picture. The bungees hook on a bit different on the Kitfox, so you have to leave room for that however. Take care, Jim Chuk

[Dusty]

Now would be the time to upgrade your fuel capacity.
My 582 kf3 has the small tanks and is the main reason I have upgraded to another plane.

[RobS]

Jim,
Looks like the you gain most of the 3 1/2" at the hips. How much do you gain at the shoulders?

[avidflyer]

Probably gained same amount at hips, and shoulders. About half way up the door opening is where the new tubing starts to angel back into the original fuselage width. That is pretty close to where your shoulders are. Jim Chuk