ready to cover the wings

[xpflyr]

Cover wings before the fuselage?
Does it matter?
Check list before I cover,, etc, pulleys on, cables in, ___________?
One piece for bottom, shrink then stitch rivet, then do top, rivet, then tape over that?
3 inch tape around perimeter of wing?
Use the piece I cut out to do flaps and ailerons?

Is there a check list out there or suggestions would be very much appreciated.
Thanks, Don.

[t j]

For what its worth. Rib lacing is easy to do. It took me about 10 hrs per wing. This was my first time and had no help. Just the manual to read.

[xpflyr]

Thanks Tom and I'm sure it's the way to go. The Kitfox has a little more speed than the Highlander. The Stewarts tech was very emphatic about really not being necessary to stitch or rivet. I heard of some who have not and so far so good so I would rather not . I believe the aerodynamics of a smooth service is the best thing you can do to achieve a cleaner, faster, less drag airplane.
Of course, if your fabric comes loose it's a big waste of time to redo! ;-)

[jtpitkin06]

The maker of the Stewarts system[sic] which is what I'm using tells me I don't need to do either one. He says the glue is strong enough and the speeds are such that rivets or stitching are not needed.
I think for the sake of looks and aerodynamics, I might go without.
.

That advice seems to contradict the published Stewart Systems recommendations.

From the Stewart Systems Procedures Manual Section 6 page 1.
"Fabric is attached to cap strips in many ways, rib lacing, screws with fabric washers, rivets and wire clips. All of these methods require the use of reinforcing tape under the attaching device. Do not rely on cement to hold fabric to cap strips."

Who at Stewart Systems told you to ignore the procedures manual for a Kitfox?

Now I'm sure there are some builders that got a certificate without lacing, that doesn't mean everyone will. Check with your DAR before you omit rib lacing. Normally the DAR wants to see you complied with accepted practices and procedures in the manufacturer's manuals. It would be a shame to finish and paint your aircraft then have the DAR reject your certificate for lack of lacing.

The Consolidated Aircraft Coatings Poly Fiber manual makes reference to the ultralight movement using glue alone but cautions, "... any ultralight or very light aircraft you plan on keeping for more that just a couple of years needs rib lacing." and; "...fabric cements were never meant to be the sole means of attaching fabric to ribs, even 1" ribs."

So neither Stewart nor Consolidated publishes any recommendation for omitting lacing at any speed.

And finally, even if you get it approved by the DAR, when you go to sell the airplane without lacing it could be a deal breaker.

John Pitkin
Greenville, TX

[Av8r3400]

John, I would estimate that 90% of the Kitfoxes flying now do not have any mechanical attachment of the fabric to the ribs other than glue.

[cap01]

my wings were covered and painted when i acquired the kit and they werent stiched . i wish they had been and i have considered doing it in the future . that being said , i have opened both wngs to install the large gas tanks . the fabric that i did remove from the ribs was certainly securely attached . i would still feel better if they were stiched

[HighWing]

I tend to agree with Larry. I think most of the cover manual recommendations focus on the quarter inch wide wood or metal rib capsstrips that are common in many airplanes. I would suspect if we were the flys on the wall during the design stage on these airplanes, talk would be about the inch wide capstrips - glue - simplicity. Forum talk about rib lacing was fairly late in coming, and the vast majority of flying Kitfoxes are not riblaced. My decision to riblace was pioneering somewhat. A little note, when I bought my first Kit in 1993, they were shipping forty (40) kits a month vs. today's three or four. The build community was enormous- likely four to six hundred or more active builders.

Lowell

[avidflyer]

I've owned and flown 3 different Avids, none of them were rib stiched and all gave no problems. When I recovered my Avid MK IV two years ago, I didn't ribstich it either. It was just fine when I flew it for almost 2 hrs this evening, and in the almost 250 hrs it's flown since I recovered it. Last summer when I covered my Kitfox 4 however, I decieded to rib stich it. Part of the reason was that I bought some left over rolls of tape and rib stich cord for next to nothing and felt like trying it. It really was kind of fun and didn't take all that long, maybe 3 or 4 hrs per wing. Back when I was flying ultralights, my Himax with 1/4" wide wood ribs was just glued, and it worked fine also. At any rate, don't be afraid of rib stiching if you think you need it as rib stiching is not all that hard to do. Take care, Jim ChukAvid MK IV (flying)Kitfox 4 (building... slowly)northern Mn

[jtpitkin06]

OK… here’s my take on Lacing vs. not


I checked with the three major manufacturers.


Stewart Systems is the only manufacturer of fabric covering materials that will commit in writing to omitting rib lacing in some cases. However, you will note they recommend you do it anyway to add a layer of protection.

My query sent to Stewart:

The installation manual 2/09 rev #2, clearly states rib lacing or other mechanical means must be used to attach fabric to wings for all aircraft along with a caution "Do not rely on cement to hold fabric to cap strips." However, I am hearing reports of verbal approval by Stewart Systems to omit lacing on an experimental aircraft with a Vne of 140 mph. Is this true? Are you amending the instructions and recommendations in the installation manual?

Thanks for the clarification.
John Pitkin

The reply from Stewart systems

For certified aircraft you need to follow the manufactures attachment
methods. For experimental you can do as you please. Our EkoBond glue
has about 3 times the shear strength of the solvent based glues. We
are also the only system certified that does not require any sewn
seams and a 1" fabric to fabric glue joint is acceptable. If you have
a 3/4" wide cap strip on the rib I would not hesitate to glue the
fabric directly to the rib in lieu of rib stitching or riveting. That
being said I personally would rib stitch because it's fast, easy, and
just that much more protection. If you decide to sell the aircraft in
the future lack of a mechanical attachment of the fabric to the ribs
may deter certain buyers.

Regards,
Jason Gerard
Stewart Systems
1-888-356-7659
www.stewartsystems.aero (http://www.stewartsystems.aero/)



The other major covering and coatings companies, Randolph Products (Seconite) and Consolidated (Poly Fiber) do not recommend glue-only rib attachment under any circumstances.

Without trying to sound like I’m standing on my soapbox… Frankly, it doesn’t matter how many Kitfoxes have omitted rib lacing in the past. Although early Kitfoxes omitted rib lacing, many were flying at lower weights and speeds. The aircraft has grown and a model 7SS wing now is lifting 700 more pounds than the Model 1. The Vne has increased from 100 to 140 mph. That’s a lot more shear on the fabric. Anyone building a current Model IV or 7 without lacing probably is pushing the envelope.

I know there are some builders out there who will say they’ve flown a bazillion hours with nothing but Scotch Tape and mucilage holding the fabric on and never had a problem. Thank your lucky stars.


Face it folks, general aviation has an abysmal safety record and experimental aviation is even worse. That alone should whap you along side of your head to do everything possible to ensure your aircraft is the safest you can build. Does that mean loading your aircraft with safety stuff to the point it only carries you and a tooth brush? No! But it does mean to use materials, procedures and techniques that provide a balance of safety vs. cost and weight.

If you are considering omitting lacing, consider the following:
Weight -Lacing adds a negligible weight. We’re talking a few ounces for an entire airplane.
Airflow - Aerodynamics are virtually unaffected. The lacing cord is low profile and is covered with cloth tape making the bumps barely visible. I doubt any difference in cruise or stall speed could be measured.
Labor- The labor involved is maybe six hours, tops… hardly worth writing home about when considering the total time required to build a plane.
Expense - Not much more than a hamburger lunch.
Appearance - Oh, yes… the prettiness factor. No lacing bumps looks nicer than bumpy… That’s a hoot! I never hear anyone say a Staggerwing Beech is ugly because it has rib lacing!!! Real pilots will know what the bumps are for and non-pilots won’t know and won’t care if you have them or not.

I think this is one of those issues where it’s time to stop the madness of doing the minimum just because you can. Rib lacing adds a huge layer of safety, costs very little, adds negligible weight and doesn’t harm the aerodynamics one bit. I see absolutely no benefit to omitting rib lacing other than reducing the build time.

That’s just this builder’s opinion.

John Pitkin
Greenville, TX

[Av8r3400]

XP - Can you explain what rivet stitching is? Are you Riveting the fabric to the ribs or is this a different type of tied stitch?

(For the record, I plan of stitching my IV-1200 rebuild project, too. Mostly because it is going to be a high-speed hotrod... :eek:)

[xpflyr]

There big, very flat alum rivets spaced every 3 inches.
They are placed on 1/2in wide reinforced tape.
This is how they do it for the Highlander.

[jiott]

For what its worth; shear strength of the glue is not whats important. It is the peel strength, which is always much less than the shear strength. The low pressure area on top of the wing will tend to try to peel the fabric up off the capstrip, a little at a time untill the whole strip is loose. All it takes is that one big unexpected patch of turbulance to get the process started.

Jim

[HighWing]

regarding John's non soapbox, "stop the madness" comments, I would like to make a comment, correct some misstatements, and then render an opinion.

With the early Kitfoxes, and I have to remind everyone here, that Kitfox did not emerge onto the scene as a 140 mph series 7, or Supersport, The build manual called for a final shrink temperature of 300°. Polyfiber insisted that final shrink temps should be 350°. The arguments raged on the forums then as now, and some caught the "fever" and the result was a lot of wasp waisted Kitfoxes with scalloped trailing edged on their wings. I think a bit of judgement is appropriate here as well, as we are not all building the same airplane. I am finishing a kit purchased in 1992. I am still using the same 1.7 oz. ( ultralight) fabric supplied with the kit - shudder, from all you that read today's literature. My reasoning is that I had 900 hours on my original 1993 kit with no issues. And fabric issues were topics that were never discussed with contemporary builders and flyers. It was simply never an issue. The same can be said with the rib lacing issue. In the day, it was simply a non issue.

"Face it folks, general aviation has an abysmal safety record and experimental aviation is even worse." John, I need at least one instance where failure to rib lace on a Kitfox has contributed to this abysmal record.

Weight - Agreed, definitely not a significant issue.

"Aerodynamics are virtually unaffected" - also no argument here.

Labor - "The labor involved is maybe six hours, tops…" Not true. A friend earns pocket money doing exactly this and reports that it takes 11 hours per wing on a Cub. I spent in excess of that on my current project - Try riblacing under the wing tank for example. For the typical 40 hour a week guy, it will take two or more weeks on his project to rib lace.

Expense - "Not much more than a hamburger lunch". Wrong again unless you are talking about the famous $100 hamburger, but with that lunch you get an airplane ride and a tank of gas. Lets look - Current ACS prices.

Rib lace tape $52.70 (half inch side by side, top and bottom)
Riblace Cord $42.15 (flat - low profile)
Needles $2.20 - $18.60 (per each - $40.75 Assortment)

Pretty much the $100 lunch, And remember that not everyone out in real world land paid $18,000 for their project with $18,000 for their engine and another $7,500 for their glass cockpit. Some guys are looking at used or alternative for reasons that others might not fully understand.

Appearance - "Oh, yes… the prettiness factor. No lacing bumps looks nicer than bumpy… That’s a hoot! I never hear anyone say a Staggerwing Beech is ugly because it has rib lacing!!! Real pilots will know what the bumps are for and non-pilots won’t know and won’t care if you have them or not." Come on, John - no one has proposed the arguement that they are not riblacing because it is ugly.

I guess what excercises me on this issue, is because this argument is right in tune with the times. Someone, whether it be government or some other superior thinking group or individual is arguing for the elimination of a more individually arrived at decision. Consider California. I as an individual home owner am in violation of a new law, that my all electric home with a decorative, inoperative fireplace needs by statute, a carbon monoxide detector. But then consider their argument - sound familiar? - 30-40 die each year from carbon monoxide poisoning. And again, it doesn't cost much more than a hamburger lunch to comply. We'll pay about $400 million to save at most 40 lives. You do the math.

For the vast majority of Kitfoxes out there, I strongly support the decision not to rib lace. For those who choose to rib lace, I have no reason to challenge that decision. I did it twice and in fact did it on the empennage of my current project for reasons of my own.

One size does not necessarily have to fit all.

Lowell

[Geowitz]

Thank you Lowell for that most reasonable response.

Does it hurt to rib stitch?...No, but does it hurt not to rib stitch?... I see no evidence of that on a Kitfox.

[jtpitkin06]

Thank you, Lowell, for your line-by-line analysis of my posting. At least I know someone is reading it in entirety.

However, you didn’t comment on one of the most important lines. Specifically that 2 of the 3 major covering manufacturers do not recommend omitting mechanical fabric attachment.

If someone using Stewart Systems wishes to omit lacing, that’s their choice. It’s not my choice, but I won’t sneer at the decision. Even so, Stewart Systems recommends you do rib lacing. Note the reply from Stewart did not say up to what speed the “glue only” application qualifies. There are no speed charts available so you are on your own.

If using something other than Stewart Systems, disregarding the manufacturer’s instructions is not in my comfort zone.

No, in my vast data base of aviation knowledge, I don’t have an example where the wing covering came off a Kitfox. My position is we shouldn’t have to wait for someone to get killed before we decide to follow the recommended procedures. We have 100 years of experience with fabric covered wings. The covering manufacturers have done massive amounts of testing to get approval for their STCs so it makes sense to me to follow their lead. The problem with simply covering a Kitfox and flying it without lacing is: You don’t know if you have a 50% safety factor or a 5% safety factor.

While I’m sure many of the readers are comfortable flying without rib lacing, there may be some who are on the fence. If I get the undecided to at least consider the pros and cons then I’ve done my job.

Thanks for reading.

John Pitkin
Greenville, TX

[xpflyr]

John, I read your whole post but even before I did, I decided to rivet stitch.
( That's their method of mechanical attachment on the Highlander )
I wasn't going to because I didn't like the look. Seems silly now but what can I say. Do I think the fabric would have come loose had I not? No,, I don't but since I'm building why not take that possibility out of mind? So I did.
Thus the wonder of experimental building. Also, that retail thought was a good one.
Don

[jiott]

Maybe I'm wrong, but it sounds to me like the discussion here is mostly about if the fabric will come off the wings and cause an emergency if you do not rib stitch. I think that is highly unlikely. The much more likely scenario is that the fabric will start to peel off the upper capstrips and eventually become unattached. Because of the tightly shrinked fabric, this condition will be almost unnoticable and hard to test for on the ground. What will happen is that in the air the fabric may lift off the capstrips, probably only a small amount, but nevertheless destroying the proper airfoil shape of the wings and causing a loss of performance and efficiency. This could remain unnoticed for years.

Jim

[HighWing]

Jim,

I agree with your assessment, but again an observation. There were a couple of Kitfoxes in a neighboring airport as I was building. Over their wing tanks, the Polybrush stuck the fabric to the wing tanks in a hap- hazard pattern as the wing tank did not have a perfectly smooth surface. This made the final color finish look pretty ugly - severely marbleized look.
I didn't want that and took great pains to avoid the fabric being glued to the top of the wing tank anywhere. It was a chore, but I was able to accomplish that goal. Also consider that the number two rib normally there is missing due to the wing tank, except for the false rib on the bottom surface - imagine a rib on the top of the wing with total loss of fabric attachment. Then sometime during the 9 years I flew it, I thought of exactly what you are proposing as the top of the wing is the critical lift portion of the airfoil and my build modification concerned me. During a group flight, I asked a buddy to come in close and see if he could see any evidence of ballooning over the wing tank. The answer was no, but then again, I suppose the greatest negative pressure would be just before the stall and I was never able to check that. However this thought reminded me of someone who did.

Check the two YouTube videos –
http://www.youtube.com/watch?v=bIsWseMbDQU
http://www.youtube.com/watch?v=gor7LhsAILs (http://www.youtube.com/watch?v=gor7LhsAILs)
I was surprised that there was not more puffing up between the ribs and false ribs especially in the stall. I think the fabric flutter in the first video is due to shrink issues. Inadequate shrinking over the wing tank may be due to the heat sink effect of the wing tank under the fabric. Folks sometime comment on wrinkles near the filler necks and the first rib. It usually happens on a very cold morning when it is visible on prefight.

Still, I agree that your proposition is likely to be the most common issue.

Lowell

[Dave Holl]

Don't know weather this link will work but the article is interesting even more so to me as I also fly this type and it was made in 1963!
http://www.lightaircraftassociation.co.uk/2011/Magazine/July/July%20safety%20spot.pdf
Dave