I could understand stitching if the Minimax was an aerobatic plane, or even if it had high wing loadings for speed or load carrying, but it isn't, and it doesn't, and in the UK I don't know of any microlights (equivalent of your 103 and LSA) that have mandatory rib stitching.
If anyone in Europe knows of any that do I'd be happy to be contradicted on that one, as my knowledge is limited. However, my point is this; planes in Europe don't fall out of the sky all day long because their fabric covered wings weren't stitched, but if they did I'm sure stitching would soon become mandatory. Currently it's not, so I can only assume that for very light and slow aircraft like ours it's not thought necessary. Furthermore, Mr Ison didn't mention stitching in the plans for the Minimax, so I can only guess that he didn't think it was necessary either, or it would have been specified.
Having said all the above here's a link to a builder who chose to stitch his ribs, and who gave a good reason for wanting to do so, and when all is said and done it's up to you to decide what to do.
I found the photos of his work, and the text that accompanied them quite inspiring and enlightening, so have a look and see if what he did helps you with your renovation.
I did it both ways. First time gluing only of the fabric top and bottom. There were no problems with it in flight even though I noted the fabric ballooning between the ribs on the upper surface. This is normal.
Due to an accident the wings required repair and recover. While removing the old fabric, I found the glued fabric would separate from the rib by easily lifting the edge. However, if I pushed up on the fabric (top surface of wing) the glue and fabric held fast. This got me to thinking; if I ever had damage while in flight, (bird strike, SAM, etc) would the ballooning effect cause the rest of the fabric stay attached to that wing? Could it cause flight control problems that I could not handle? Maybe yes, Maybe no.
Second time around I elected to rib stitch, ref: FAR 43, a guide. Total weight added was approx 1 1/2 lbs for both wings, reinforcing tape, waxed cord and covering tape. This also gave me much greater peace of mind. As a side, I still stayed with in 103 limits. Think about it.
Furthermore, Mr Ison didn't mention stitching in the plans for the Minimax, so I can only guess that he didn't think it was necessary either, or it would have been specified.
The MiniMax 1030 plans for the Part 103 compliant models clearly state that rib stitching is optional.
But construction manuals for the heavier Maxes do state " Rib stitching is recommended if you plan to operate with heavier engines or outside of the Pt 103 flight envelope."
Due to an accident the wings required repair and recover. While removing the old fabric, I found the glued fabric would separate from the rib by easily lifting the edge. However, if I pushed up on the fabric (top surface of wing) the glue and fabric held fast. This got me to thinking; if I ever had damage while in flight, (bird strike, SAM, etc) would the ballooning effect cause the rest of the fabric stay attached to that wing? Could it cause flight control problems that I could not handle? Maybe yes, Maybe no.
That's the exact mentality I am thinking about. Yeah, it might not be needed, but it sure seems like good insurance. It doesn't seem THAT hard with the proper jigs.. Also my father, who will be helping me redo the wings (He loves this kind of tedious stuff, he built a great many balsawood model aircraft when I was younger) said that he won't help me unless I do everything I can do make it as safe as possible, and once I told him about rib stitching he was all for it, so it sounds like my help may have made the decision for me. Also my Kawi 440 is indeed outside the envelope of the max 1030 just a bit..
I've seen two schools of thought, btw. Glue onto ribs, then stitch, or don't glue to ribs, and stitch is the only thing holding it on. What is better?
Seriously though... I don't mind helping folks... But I, for one, am not going to sit here and systematically type in the entire "Superflight Covering System Manual" for you. If you are going to use the Superflight system7 covering system, and do it by the book, then you are going to need the book to do it by!
Seriously though... I don't mind helping folks... But I, for one, am not going to sit here and systematically type in the entire "Superflight Covering System Manual" for you. If you are going to use the Superflight system7 covering system, and do it by the book, then you are going to need the book to do it by!
My apologies to you ITman496, after reading over this post I seemed a bit harsh that day. So my apologize if I have offended you, and even if I have not, I still apologize for my harshness.
According to the Superflight manual, the fabric is both glued and stitched to the rib. The thought of just rib stitching alone scares me more than not rib stitching at all. All the load focused on each individual stitch instead of spread out all along the rib surface? Doesn't sound like a good idea to me. Someone said on another thread that the rib stitching was only there incase the glue failed. How ever, I suspect the glue and the stitching work together as bobnafe suggested above. Seems to reason the stitching would keep the glue from peeling off in shear.
I had decided long ago not to rib stitch mine because the wing loading and flight speeds aren't high enough to need it, but darned if you haven't just about changed my mind. It's still not to late to rib stitch my wings.
It's fine, no offense taken. I ask a lot of questions when I'm about to spend money, I tend to misunderstand a lot and wind up buying the wrong things. For example, if I had not hammered you with questions, I'd be using the complete polyfiber system!
I'm not too worried about the stitching. It doesn't.... SEEM like it will be that hard? I might use my 3d printer to try and make some jigs to help guide the needles to get extra consistent spacing. I'm not sure what to do about the compression members. I guess the rib stitching tugging on them doesn't matter too much?
My primary desire for rib stitching is to stop the fabric from suffering some kind of cascade peel failure if the fabric somehow comes off the rear of the wing. At first, nothing would happen. But then a little would peel, and start flapping. Then presumably, much like how a trickle of water leaking on a dam can rapidly erode into a massive failure, the flapping would become more violent, more would tear, more violent, in a big feedback loop that results in total fabric failure. At least the stitching would act sort of like I heard they do with the way they design the aluminum skin of jet liners, to stop cracks from spreading all the way around the fuselage, making them stop at a point and spread no further. With stitching, it might separate a bit, but it would have to fight a lot harder to really yank it all off.
I finally just ordered everything. If I can't find more space I might have to tarp the hell out of the max and leave a few bags of rice and keep it outside while I do each wing. Hopefully not but we shall see..
You could laminate a piece of wood stock thick enough to make up the difference in thickness of your lower compression members. A lamination would be stronger than one solid piece of wood anyway. It certainly wouldnt detract from the strenght of the existing structure.
Interesting idea.. Just so we're clear, this is what I'm talking about. Now if there is a gap on those members, then this is a moot point, but from the angle I can look, I don't see one..
Is it okay that the lacing tugs on them sidways like that, potentially bending them in a little if the lacing tensions up? Or is the key not to pull that hard? See the diagram:
Note: I just realized that there is likely only 1 side of compression members, but the point still stands. How does one navigate around them?
Also, unrelated question. The long thin strips of wood you are using to do the turtle deck, plus I guess whatever the whole dang aircraft is made of... What is it called? Where can I buy more of it? I want to redo my deck some day.. and I need wood!
I know you and your dad will enjoy discussing the experience and time together for many years to come. Also, needles can be shaped by heat heat bent and quenched in water.
Yeah, I'm no expert on rib stitching, but I wouldn't include the compression member in the stitch. You should be able to get around it with a curved needle. bobnafe made a good suggestion, there are tons of videos on youtube about covering and rib stitching.
The long thin strips you are referring to are white pine. You can use sitka spruce, engelmann spruce, douglas fir, ect... There maybe some other substitutes, you will just have to research it. You can get white pine from your local lumber yard most likely. Just make sure you know how to grade it for aircraft use. The plywood is 1.5 mm finnish birch aircraft plywood, this you will have to get from Aircraft Spruce & specialty Company or other aircraft supply of your choosing. The turtle deck is not structural so its not critical but you still want to do it right.
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Just making conversation while I wait for it. But no worries, I'll refer to that.
